The breakthrough came from a technical challenge. Unlike in the nematode C. elegans, where cell corpses can be spotted with Nomarski microscopy, dying cells are invisible in live Drosophila tissues. Steller’s laboratory first developed a technique using the vital dye acridine orange to visualize apoptotic cells in live fly embryos. Screening a collection of 129 chromosomal deletions covering more than half of the genome, only three overlapping deletions on the third chromosome produced embryos completely lacking acridine orange staining. A smaller deletion, Df(3R)H99, narrowed the interval, and chromosomal walking across the entire H99 region allowed the team to isolate the genes responsible for the cell-death phenotype.

Reaper was the first gene identified in that interval. Strikingly, its mRNA distribution largely anticipated the pattern of apoptosis in the Drosophila embryo, suggesting that the gene acts as a global convergence point for many different signaling pathways. Subsequent studies confirmed that reaper is a direct transcriptional target of an extraordinary range of inputs: Hox genes, segmentation genes, steroid hormone signaling, p53, microRNAs, JNK signaling, and histone-modifying enzymes. In contrast to its vast regulatory region, reaper encodes a tiny 65-amino-acid protein bearing an N-terminal IAP-binding motif (IBM) that mediates direct binding to and neutralization of DIAP1, the major inhibitor of apoptosis in flies.

That mechanism introduced a principle that now underpins cell death regulation across higher animals: apoptosis can be triggered by precisely controlled expression of IAP antagonists, rather than activation of caspases alone. DIAP1 is an essential survival factor required to prevent unwanted caspase activation in virtually all somatic cells. In living cells, DIAP1 and its mammalian counterpart XIAP repress caspases by direct binding and ubiquitylation. Deleting the RING domain of either protein completely abrogates anti-apoptotic activity, demonstrating that the E3-ligase function of these IAPs is essential and evolutionarily conserved. Once Reaper accumulates in a doomed cell, it binds DIAP1 and promotes self-conjugation and degradation of the protein, removing the major brake on caspase activity in a rapid switch of cell fate.

Reaper did not act alone. Shortly after its isolation, two additional pro-apoptotic genes, head involution defective (hid) and grim, were identified in the same H99 region, and a fourth family member, sickle, was found in 2002. Collectively known as RHG genes, they share an N-terminal IBM, a role in developmental apoptosis, and regulation by multiple developmental and stress pathways. Hid, a 410-amino-acid protein, is a direct molecular target of the Ras-MAPK pathway: survival signals activate MAPK, which phosphorylates and inhibits Hid, thereby saving cells that are primed to die. This mechanism is used, for example, to match the number of glial cells in the Drosophila CNS midline to neurons, which secrete the TGFα-like ligand Spitz that activates EGFR only on glial cells in contact with neurons.

The RHG proteins also cooperate through hetero-multimerization. Reaper and Grim contain an α-helical GH3 domain that promotes multimerization and localization to the outer mitochondrial membrane. Co-expression of grim with reaper or hid induces significantly higher levels of cell death than expression of these genes individually. Hid localizes to mitochondria via its C-terminal transmembrane domain and can recruit Reaper to the mitochondrial outer membrane, allowing more effective killing. Some cell types, including embryonic neuroblasts, do not express Hid and are killed by coordinated expression of reaper, grim, and possibly sickle, underscoring that different cell types have differential requirements for these proteins.

The conceptual bridge to mammals came six years after reaper, with the identification of Smac/DIABLO, Omi/HtrA2, and ARTS as mitochondrial IAP antagonists. The IBM is structurally conserved between Drosophila and mammalian IAP-antagonists and is required for IAP-binding and cell killing. Smac/DIABLO and Omi/HtrA2 reside in the mitochondrial intermembrane space and require mitochondrial outer membrane permeabilization to access cytosolic IAPs. ARTS, by contrast, shares no obvious sequence homology with RHG proteins but many functional similarities with Reaper: it does not require MOMP, acts upstream of cytochrome c and Smac/DIABLO, induces ubiquitin-proteasome-mediated degradation of XIAP, and is transcriptionally induced upon DNA damage by direct binding of p53 to its promoter. Inactivation of ARTS in mice elevates XIAP protein levels and attenuates stem cell apoptosis, suggesting ARTS may be a functional analog of Reaper.

Beyond the core machinery, Drosophila has proven indispensable for understanding caspase regulation in vivo. The initiator caspase Dronc is homologous to mammalian caspase-9 and requires binding to Dark, the Apaf-1 homolog, to form the apoptosome. Drice and Dcp-1 are caspase-3-like effector caspases that carry out cellular demolition. Although cytochrome c appears not strictly required for apoptosome activation in flies, mutations can delay developmental apoptosis, consistent with the idea that cytochrome c accelerates rather than initiates the caspase cascade. Mitochondrial dynamics and reactive oxygen species also critically influence cell death outcomes, and the Drosophila apoptosome functions analogously to its mammalian counterpart, making the fly a powerful model for caspase biology.

One of the most striking lessons from the fly is that apoptosis is not merely a demolition crew. Over the last two decades, Drosophila has emerged as a leading model for non-lethal roles of caspases in development, tissue remodeling, cell differentiation, proliferation, and neuronal remodeling. The first mechanistic proof that apoptotic caspases can drive differentiation without inducing apoptosis came from mouse lens fiber cell differentiation, overturning the dogma that caspases are inherently lethal. In Drosophila, caspase activity is essential for spermatid individualization, where inhibition prevents cytoplasmic clearance and results in male sterility. During metamorphosis, larval neurons prune their axons and dendrites in response to the steroid hormone ecdysone, and this remodeling requires localized activation of Dronc selectively within neurites destined for removal. Robust maintenance of DIAP1 and survival pathways in the soma ensures apoptotic thresholds are never reached, allowing a micro-apoptotic program powerful enough to remodel defined domains while preserving viability.

Drosophila also revealed that apoptotic cells can release mitogenic signals to stimulate proliferation of neighboring cells, a phenomenon now generally referred to as apoptosis-induced proliferation (AiP). Cells undergoing apoptosis in response to DNA damage stimulate proliferation of neighboring cells and aid tissue regeneration, mediated by p53-driven transcriptional activation of reaper and hid, inhibition of DIAP1, and de-repression of caspases. JNK signaling stimulates a positive feedback loop between p53 and RHG genes that amplifies the initial stimulus. The mitogens secreted by apoptotic cells include Wingless, Decapentaplegic, and Hedgehog. Because AiP is evolutionarily conserved, these findings carry obvious implications for tissue regeneration and cancer: chemotherapy using DNA-damaging agents may cause AiP, which in turn may contribute to the formation of metastases.

In 1994, PCD was basically synonymous with apoptosis. Since then, many forms of non-apoptotic PCD have been described, including autophagy-dependent developmental cell death, regulated necrosis, pyroptosis-like inflammatory death, and immune-induced death. While a direct physiological role of reaper in these processes remains to be demonstrated, reaper may contribute under pathological conditions. When apoptosis is blocked by caspase inhibitors, Eiger, the fly TNF homolog, can induce necroptosis in a process requiring the initiator caspase Dronc. Since Dronc is inhibited by DIAP1 and this repression is relieved by RHG proteins, reaper and its partners may affect other forms of cell death when core apoptotic pathways are genetically or pharmacologically inhibited.

Due to its genetic and anatomical accessibility, Drosophila continues to drive conceptual advances with relevance to cancer, neurodegeneration, immunity, and regeneration. Over the past three decades, the fly has provided fundamental insights into apoptosis, the non-lethal use of apoptotic proteins, alternative death pathways, and proliferation-death coupling. Many processes controlled by RHG proteins in Drosophila mirror phenomena in vertebrates, and RHG genes will remain essential tools for probing how a constitutively expressed cell suicide program is contained by the layered checkpoints that evolution has built from worms to flies to mammals.

Subject of Research: The legacy of the Drosophila reaper gene in apoptosis research

Article Title: Thirty years of reaper: lessons learned from programmed cell death in Drosophila

Article References: Steller, H. (2026). Thirty years of reaper: lessons learned from programmed cell death in Drosophila. Frontiers in Cell Death, 5, Article 1770008. https://doi.org/10.3389/fceld.2026.1770008

Image Credits: AI Generated

DOI: 10.3389/fceld.2026.1770008

Keywords: apoptosis, reaper, Drosophila, caspases, IAP, programmed cell death, Thirty, years, lessons, learned, programmed, cell

The new study, published in the journal Biogerontology by S. Deepashree and T. Shivanandappa, tackles a question that has lingered at the edge of aging research for years. Oxidative stress resistance is widely regarded as a key contributor to extended longevity, but whether this trait can be transmitted across generations, and by what mechanism, has remained poorly understood. Epigenetic inheritance, the passage of traits through mechanisms other than DNA sequence, has been demonstrated for environmental stress responses in organisms ranging from nematode worms to plants, but its role in the longevity phenotype of Drosophila has been largely unexplored. The Mysore team set out to fill that gap using a rigorous experimental design: reciprocal crosses between a normal-lifespan strain and the long-lifespan strain, followed across three generations.

Reciprocal crossing is the crucial trick here. By mating normal-lifespan males with long-lifespan females, and separately long-lifespan males with normal-lifespan females, the researchers produced offspring that carry essentially the same nuclear genes in both cases but differ in the cytoplasmic and maternal environment they inherit. Any consistent difference between the two reciprocal F1 hybrids cannot be explained by nuclear genotype alone. It points instead to the maternal lineage, whether through the egg’s cytoplasm, its mitochondria, or epigenetic marks laid down during oogenesis. The team then tracked survival, locomotor performance, and antioxidant defenses through the F1 and F2 generations, exposing flies at each stage to paraquat, a herbicide that generates superoxide radicals and is a standard laboratory probe for oxidative stress resistance.

The baseline difference was stark. Long-lifespan flies tolerated paraquat exposure far better than their normal-lifespan counterparts, and within both strains, females were more resistant than males, consistent with earlier work from the same group showing sex differences in oxidative stress defense. But the reciprocal crosses revealed something more intriguing. Female offspring of long-lifespan mothers and normal-lifespan fathers survived paraquat challenge with significantly lower mortality than female offspring of the opposite cross, and this maternal advantage persisted into the F2 generation. The effect was sex-specific: it appeared clearly in daughters but not in sons, suggesting that the maternal transmission of stress resistance interacts with the offspring’s own sex-specific physiology.

Locomotor resilience emerged as the most robust maternally inherited trait of all. Fruit flies instinctively climb upward when tapped to the bottom of a vial, a behavior measured as negative geotaxis, and paraquat exposure degrades this performance as oxidative damage accumulates in the nervous system. The researchers found that the offspring of long-lifespan mothers recovered locomotor function under oxidative challenge better than offspring of normal-lifespan mothers, and this advantage appeared in both sexes and in both the F1 and F2 generations. Narrow-sense heritability estimates for negative geotaxis in males provided a quantitative measure of this differential transmission through mothers, confirming that the maternal contribution to locomotor resilience is a genuine, measurable heritable component rather than a statistical artifact.

Among the biochemical defenses the team measured, glutathione stood out as the most consistent transgenerational maternal antioxidant trait. Glutathione is the cell’s principal endogenous antioxidant, a tripeptide that neutralizes reactive oxygen species directly and feeds the enzymatic systems that detoxify peroxides. Offspring of long-lifespan mothers had significantly higher glutathione levels than offspring of normal-lifespan mothers, in both sexes and in both the F1 and F2 generations. Most strikingly, the F2 generation showed positive recombination values for glutathione, indicating not just persistence of the maternal effect but transgenerational amplification of glutathione-based antioxidant capacity. The biochemical legacy of the long-lived mother, in other words, grows stronger as it passes down the generations.

Catalase told a different story. This enzyme, which breaks down hydrogen peroxide, showed near-zero heritability across the reciprocal crosses, a result the researchers interpret as consistent with catalase’s predominantly nuclear regulation. Because catalase is controlled almost entirely by genes in the cell nucleus, its expression is determined by the offspring’s own genotype rather than by anything the mother contributes through the egg. The contrast between glutathione and catalase is therefore highly informative: it suggests that the maternally inherited component of stress resistance is not a blanket enhancement of all antioxidant systems, but a specific, trait-dependent transmission that favors cytoplasmic and non-nuclear mechanisms.

Variance partitioning analysis reinforced this picture. In the parental generation, the mother’s genotype accounted for prominent contributions to reactive oxygen species levels, lipid peroxidation, superoxide dismutase activity, and locomotor performance. By the F1 and F2 generations, these maternal contributions to the enzymatic and damage markers had diminished, while the effects on locomotion and glutathione persisted. The pattern suggests that the maternal influence on stress resistance is strongest in the traits most closely tied to cytoplasmic inheritance, and that the transmission is selective rather than uniform. Locomotion and glutathione regulation, the authors conclude, are the primary subjects for subsequent studies on the cytoplasmic, epigenetic, and mitochondrial pathways that mediate transgenerational stress resistance.

The implications reach well beyond the fruit fly. If the adaptive stress resistance that underpins extended longevity can be inherited through the maternal line in a trait-dependent fashion, then the search for the genetic and epigenetic architecture of aging must include mechanisms that standard nuclear genetics cannot capture. Mitochondrial DNA, inherited exclusively through the mother in most animals, is an obvious candidate, as are cytoplasmic factors deposited in the egg and epigenetic marks that survive the wave of reprogramming that normally erases them after fertilization. The Mysore team’s long-lifespan strain, isolated decades ago and studied continuously since, has now become a model not just for extended longevity but for the non-genomic channels through which a longevity phenotype can echo across generations. As aging research increasingly embraces the idea that heritability is more than DNA sequence, the humble fruit fly is showing exactly where to look.

Subject of Research: Genetics

Article Title: Oxidative stress resistance of the extended longevity phenotype of Drosophila under paraquat exposure is heritable: influence of maternal genotype on the offspring

Article References: Deepashree, S., & Shivanandappa, T. (2026). Oxidative stress resistance of the extended longevity phenotype of Drosophila under paraquat exposure is heritable: influence of maternal genotype on the offspring. Biogerontology, 27(6), Article 180. https://doi.org/10.1007/s10522-026-10523-z

Image Credits: AI Generated

DOI: 10.1007/s10522-026-10523-z

Keywords: Drosophila, oxidative stress, transgenerational inheritance, maternal effects, longevity, Oxidative, stress, resistance, extended, phenotype, under, paraquat

The review, led by Shruthi Bandyadka and Kimberly McCall of Boston University together with Hila Toledano of the University of Haifa, focuses on germline cysts. In most animals, germ cells do not develop as isolated units. Germline stem cells give rise to daughters that divide with incomplete cytokinesis, producing clusters of cells joined by intercellular bridges. In the testis, every cell of such a cyst differentiates into a spermatocyte. In the ovary, typically one cell becomes the oocyte while the others serve as nurse cells that pump their cytoplasmic contents into the developing egg. These cysts are ancient, found in the male germline of most if not all animals, and they present a logistical puzzle: how do you eliminate part of an interconnected collective without damaging the tissue around it?

The answer, the authors argue, is phagoptosis, a form of regulated cell death in which the phagocytic machinery of one cell is turned against another cell that would otherwise remain alive. Phagocytes classically clear corpses, engulfing cells that have already died by apoptosis and displaying eat-me signals such as phosphatidylserine. In phagoptosis, the phagocyte is the executioner. The phenomenon was first characterised in the brain, where microglia engulf viable but stressed neurons, and it has since been documented in multiple tissues. What the new review highlights is that the germline, of all places, has emerged as a premier model for this cellular assassination.

The most thoroughly analysed system is the Drosophila ovary. Each egg chamber contains the oocyte, its nurse cells and a monolayer of somatic follicle cells. Two distinct death paradigms operate here. Under starvation or stress, a checkpoint roughly halfway through oogenesis, between stages 7 and 9, triggers degeneration of the entire egg chamber; this midstage death is apoptotic and autophagic, and follicle cells expressing the phagocytic receptor Draper engulf the dying germ cells. But the developmental death of nurse cells at the end of a healthy oogenesis, from stages 12 to 14, is something else entirely. It proceeds despite disruption of caspases and autophagy genes in the germline, ruling out both apoptosis and autophagy as essential mechanisms.

Genetic ablation experiments revealed that a specialised subset of follicle cells, the stretch follicle cells that extend between the nurse cells, are required for nurse cell death. These epithelial cells act as non-professional phagocytes. They require the phagocytosis genes draper, ced-12 and the JNK signalling pathway, and loss of any of these blocks the DNA fragmentation and nuclear lamina breakdown that characterise nurse cell death. Remarkably, four to five stretch follicle cells collaborate around each nurse cell, and complete coverage by this phagocytic collective is required for clearance. This is not the single phagocytic cup of textbook engulfment; it is a coordinated, multi-cell strangling operation.

The final blow is delivered by acidification. Vacuolar ATPases, proton pumps normally confined to lysosomal membranes, become enriched on the plasma membrane of the stretch follicle cells, secreting protons into the extracellular space around the nurse cell remnants. Chloride channels localise similarly, presumably balancing the ion gradient. The low pH activates cathepsin proteases such as CP1 released by the follicle cells, and together with DNaseII these enzymes degrade the nurse cell lamins and chromatin. The transcription factor Mitf, a master regulator of V-ATPase genes, is required, and Draper is needed for acidification itself, suggesting the receptor influences proton pump deployment. In effect, the lysosomal acidification machinery is repurposed for extracellular killing: the nurse cells are digested from outside rather than inside a phagolysosome.

Strikingly similar logic operates in the Drosophila testis. Spermatogonial cysts, clutches of 2, 4, 8 or 16 interconnected germ cells wrapped by somatic cyst cells, die spontaneously under homeostatic conditions; imaging of fixed testes suggests 20 to 30 percent of mitotic cysts are engaged in death at any time, and the process takes more than 24 hours from initiation to completion. This death is non-apoptotic: loss of the effector caspases Drice and Dcp-1 does not reduce it, autophagy mutants do not affect it, and the caspase-9 homologue Dronc acts atypically, independently of its catalytic activity. Dying cysts co-stain with LysoTracker and TUNEL, and mutants in lysosomal genes including cathepsin D, deep-orange, carnation and DNaseII significantly decrease the number of dying cysts, squarely implicating lysosomes.

Live imaging then established that the somatic cyst cells are the killers. Lamp1-positive phagosomes of cyst cell origin aggregate between cyst cells and germ cells before acidification begins, and Rab5 and Rab7 positive endosomes localise around the entire spermatogonium, indicating that the interconnected germ cells are engulfed as a single unit. RNAi knockdown of Rab5 in cyst cells completely arrests germ cell death, a necessary qualifier for phagoptosis. The receptors Draper and Croquemort play complementary roles: draper and ced-12 are essential for engulfment but not acidification, whereas crq affects acidification without disrupting engulfment. Loss of engulfment causes hyperplasia at the testis apex, where live spermatogonia accumulate, a phenotype mirrored in p53 null mutants, pointing to the tumour suppressor as an intrinsic inducer of germ cell death, a role conserved in mice under mild heat shock.

The conservation extends to mammals. In the fetal mouse ovary, nurse cells in germline cysts of up to 32 cells are eliminated by the surrounding pregranulosa cells. LysoTracker activity rises in nurse cells during late oogenesis, and inhibition of V-ATPase activity with bafilomycin A1 abolishes this signal and leaves nurse cell nuclei persisting. Single-cell RNA sequencing shows late-oogenesis pregranulosa cells expressing multiple V-ATPase subunits and cathepsins Ctsb, Ctsd, Ctsl and Ctsz, the orthologue of Drosophila Cp1. Apoptosis also occurs simultaneously, albeit at far lower levels, apparently to remove non-viable germ cells, suggesting that specific cues deterministically activate one pathway or the other.

Why would evolution place a destructive acid bath so close to a precariously incubated gamete? The authors speculate that acidification may harm nurse cells without impairing the oocyte, and may even benefit gamete competence; the rodent male reproductive tract maintains an acidic luminal environment, by V-ATPase proton secretion, to help nascent sperm mature. Extracellular proton secretion by plasma membrane V-ATPases is known in kidney intercalated cells and osteoclasts, but its involvement in cell killing thus far appears confined to gametogenesis. Many questions remain: how the nurse cell plasma membrane is disposed of, whether trogocytosis or cellular nibbling precedes acidification, what eat-me signals mark live germ cells for recognition when phosphatidylserine appears only after engulfment, and how the Toll pathway and single-cell gene expression programmes shape the phagocytic fate of these somatic cells. What is already clear is that somatic cells across the animal kingdom share a conserved, non-apoptotic mechanism for pruning the germline, one that turns the protective envelope of the cyst into its executioner.

Subject of Research: Non-apoptotic germline cyst cell death via somatic cell acidification

Article Title: Sacrificing cells of the cyst: non-apoptotic cell death in germline cysts via acidification

Article References: Bandyadka, S., Tohline, L., Wandji, G.-V., Toledano, H., & McCall, K. (2025). Sacrificing cells of the cyst: non-apoptotic cell death in germline cysts via acidification. Frontiers in Cell Death, 4, Article 1677498. https://doi.org/10.3389/fceld.2025.1677498

Image Credits: AI Generated

DOI: 10.3389/fceld.2025.1677498

Keywords: germline cyst, phagoptosis, Drosophila, cell death, acidification, V-ATPase, oogenesis, spermatogenesis, Sacrificing, cells, cyst, non-apoptotic

The central premise of the review is deceptively simple. Neurons are postmitotic cells, meaning they have permanently exited the cell cycle and cannot divide to replace themselves. This makes them extraordinarily long-lived but also vulnerable to the slow accumulation of unrepaired damage. Because the nucleus houses the genome and controls gene expression, RNA processing, DNA repair, and the traffic of molecules between nucleus and cytoplasm, any compromise to nuclear structure can cascade into dysfunction. In postmitotic neurons, LaminB is the dominant component of the nucleoskeleton, the filamentous scaffold that anchors chromatin to the inner nuclear membrane and connects, through the LINC complex, to the cytoskeleton and ultimately the extracellular matrix. This architecture allows the nucleus to act as a mechanosensor, translating physical forces from the environment into changes in genome organization and gene activity.

Napoletano proposes a framework of what he calls hallmarks of neuronal health, adapted from the broader hallmarks of health concept articulated by López-Otín and Kroemer. These include the integrity and repair of the cell body, axons, dendrites, and organelle membranes; long-term maintenance of molecular recycling and turnover; preservation of cell identity; alignment of neuronal output with environmental demands; sustained bioenergetic competence; and adaptive structural plasticity. Within this framework, the nuclear envelope and its LaminB scaffold emerge as a central hub, interfacing with essentially every other hallmark. When compartmentalization fails, for instance, nuclear DNA can leak into the cytoplasm, activating innate immune sensors such as cGAS-STING and triggering inflammatory pathways that accelerate degeneration.

The structural role of LaminB is well established. The protein is anchored to the inner nuclear membrane through a lipid modification called farnesylation, forming a meshwork that interacts with chromatin, RNA-binding proteins, transmembrane proteins of the LEM domain family such as Emerin and LAP2, and components of the nuclear pore complex. Mammals express two B-type Lamins, LMNB1 and LMNB2, with partially redundant functions, whereas Drosophila carries a single ortholog known as LaminDm0. This genetic simplicity has made the fly an exceptionally powerful system for dissecting LaminB function. When LaminB is knocked down in postmitotic fly neurons, the animals show neurodegeneration, reduced lifespan, and impaired locomotor ability, directly linking nuclear scaffold integrity to neuronal survival in vivo.

One of the most striking examples of LaminB dysfunction comes from Drosophila models of tauopathy, the family of neurodegenerative conditions that includes Alzheimer’s disease. In these flies, expression of mutated human Tau protein drives hyper-polymerization of actin fibers, which push against the nucleus through the LINC complex. The resulting mechanical load deforms the nuclear envelope, causing LaminB to buckle and RNA to accumulate abnormally within nuclear invaginations. This toxic buildup of messenger RNA inside deformed nuclei provides a tangible mechanistic link between cytoskeletal pathology and nuclear failure, illustrating how mechanical stress, long considered a peripheral concern in neurodegeneration research, can directly compromise the genome’s physical container.

Beyond its structural role, LaminB regulation emerges as a dynamic stress-integration system governed in part by post-translational modifications, particularly phosphorylation. The review highlights the enzyme Pin1, a phosphorylation-dependent peptidyl-prolyl isomerase conserved from yeast to humans. Pin1 recognizes serine or threonine residues that precede proline in target proteins, and by catalyzing cis-trans isomerization at these sites it acts as a conformational checkpoint that fine-tunes signaling. Pin1 is overexpressed in many cancers, where it promotes tumor progression, but it is reduced or inactivated during aging and in Alzheimer’s disease. Loss of Pin1 function in Drosophila mutants and in knockout mice causes premature aging phenotypes, including degeneration of brain neurons, retina, and gonads, positioning the enzyme as a molecular switch between proliferative stress responses and neuronal vulnerability.

Drosophila studies pioneered the discovery of a pathway linking Pin1 to genome stability under mechanical stress. When Pin1 levels or activity decline, as occurs with aging and in Alzheimer’s disease, the LaminB meshwork deforms under mechanical load. This deformation triggers degradation of Heterochromatin Protein 1 alpha, the major promoter of heterochromatin condensation, via the ubiquitin ligase Hecw, whose mammalian counterparts are NEDL and HECW-1/2. The loss of HP1a unleashes heterochromatin derepression and mobilization of transposable elements, mobile genetic sequences that insert themselves into DNA and cause cumulative damage. This cascade ultimately drives cell death and activates pro-inflammatory signaling, providing a mechanistic explanation for how mechanical stress in aging neurons translates into genome instability and degeneration.

The review also describes a distinct non-apoptotic cell death pathway termed karyoptosis, uncovered through Drosophila models of proteotoxic stress. When autophagy, the cellular recycling system, is chronically impaired, as occurs in polyglutamine diseases such as Dentatorubral-pallidoluysian atrophy, in Alzheimer’s disease, in C9ORF72-associated amyotrophic lateral sclerosis and frontotemporal dementia, and in autolysosomal disorders such as Vici syndrome, neurons activate a regulated death program involving p38-mediated site-specific phosphorylation of LaminB. This phosphorylation causes the nuclear scaffold to break down, leading to cellular expulsion of nuclear material. Unlike apoptosis, which relies on caspase-driven dismantling, karyoptosis represents a fundamentally different mode of neuronal demise centered on nuclear envelope failure, and its causal chain from LaminB phosphorylation to execution has not yet been fully dissected in mammalian neurons in vivo.

Therapeutically, these findings suggest multiple points of intervention. Preserving the Pin1-dependent LaminB-heterochromatin axis could protect neurons from mechanical stress-induced genome instability. Promoting nuclear envelope repair through LEM-BAF-ESCRT-III complexes might seal ruptures before they trigger inflammatory cascades. Inhibiting retrotransposon activity, for example with reverse transcriptase inhibitors, could limit the DNA damage caused by mobile elements. Blocking pathological LaminB phosphorylation by p38 MAPK might prevent karyoptosis, while enhancing autophagy-lysosomal function could reduce the proteotoxic stress that drives nuclear breakdown in the first place. The review notes that similar LaminB-dependent mechanisms operate in non-neuronal cells as well; in cancer cells, for instance, tethering of the transcription factor CREB3 to the Lamin nucleoskeleton maintains nuclear envelope integrity, and its abnormal cleavage under endoplasmic reticulum stress triggers karyoptosis.

Important caveats remain. B-type Lamins are dispensable for the survival and growth of mouse embryonic stem cells, and mice can develop without them, albeit with significant defects in neuronal shape, nuclear integrity, migration, and cortical layering. Germline duplication of LaminB1 causes autosomal dominant leukodystrophy, an adult-onset demyelinating disease driven by oligodendrocyte dysfunction rather than neuronal death, underscoring that LaminB biology is context-dependent. Nevertheless, the convergence of evidence from flies, mice, and human genetics positions LaminB regulation as a central determinant of neuronal homeostasis. As the population ages and neurodegenerative diseases impose an ever-growing burden, understanding how the nuclear scaffold integrates stress signals and decides between adaptation and death may prove one of the most consequential frontiers in modern cell biology.

Subject of Research: LaminB-dependent nuclear homeostasis in neuronal aging and cell death

Article Title: At the nucleus of neuronal health: Drosophila insights into LaminB-dependent homeostasis in aging and cell death

Article References: Napoletano, F. (2026). At the nucleus of neuronal health: Drosophila insights into LaminB-dependent homeostasis in aging and cell death. Frontiers in Cell Death, 5, Article 1954383. https://doi.org/10.3389/fceld.2026.1954383

Image Credits: AI Generated

DOI: 10.3389/fceld.2026.1954383

Keywords: LaminB, Drosophila, nuclear envelope, neurodegeneration, karyoptosis, Pin1, heterochromatin, transposable elements, mechanical stress, autophagy, p38 MAPK, neuronal aging

The research team, led by Hyun-Jin Na and Mi Jeong Sung, with Min-Sun Kim as co-author, used the fruit fly Drosophila melanogaster to dissect how redox imbalance derails intestinal stem cell function during aging. The fly midgut has become a premier model for this kind of work because its stem cells can be tracked, genetically manipulated, and compared across the lifespan with remarkable precision. As flies age, their intestinal stem cells proliferate excessively, the epithelial barrier deteriorates, and reactive oxygen species accumulate, a triad of defects that mirrors what happens in mammalian intestines, including our own.

Chlorogenic acid, abbreviated CGA, is an ester of caffeic acid and quinic acid that ranks among the most abundant polyphenols in the human diet. Coffee drinkers consume hundreds of milligrams daily, and the compound has attracted attention for anti-inflammatory, antioxidant, and metabolic effects in contexts ranging from diabetic vascular damage to chronic kidney disease. What remained unclear was whether CGA could specifically protect the stem cell compartment of an aging intestine, and if so, through what molecular channel the protection flows.

To answer these questions, the researchers deployed three complementary fly models: naturally aging flies, flies subjected to hydrogen peroxide-induced oxidative stress, and flies fed a high-sucrose diet that accelerates intestinal decline. Across all three conditions, CGA treatment was associated with reduced accumulation of reactive oxygen species, diminished DNA damage response signaling, and suppression of the aberrant stem cell proliferation that characterizes stressed and aged guts. The compound also improved intestinal barrier integrity, a functional readout with direct relevance to age-related leaky gut, and reduced stress-associated autophagic responses in the epithelium.

The genetic centerpiece of the study is CncC, the Drosophila ortholog of the mammalian transcription factor NRF2. NRF2 sits at the apex of cellular antioxidant defense, binding to antioxidant response elements in DNA and switching on genes that neutralize oxidants, repair damage, and maintain proteostasis. Earlier work from the Jasper and Bohmann laboratories had established that Keap1-Nrf2 signaling controls intestinal stem cell proliferation in flies, making the pathway a natural candidate for mediating dietary protection. When the team analyzed flies lacking functional CncC, the protective effects of CGA on stem cell dynamics and oxidative stress markers were lost, demonstrating that the compound requires this pathway to exert its benefits.

Importantly, the authors are careful about what their data do and do not show. The study does not establish direct activation of CncC by the parent CGA molecule or by its metabolites. This distinction matters because polyphenols often act indirectly, for example by generating a mild oxidative signal that triggers the cell’s own defense systems, or through gut microbial conversion into more active species. The requirement for CncC-dependent capacity, rather than proof of direct binding, positions CGA as an upstream modulator whose precise molecular target remains an open question for future work.

Transcriptomic analysis using RNA sequencing added a genome-wide dimension to the findings. The researchers profiled gene expression changes associated with CGA treatment and found alterations in pathways related to antioxidant defense, genome maintenance, and cell cycle regulation. These transcriptional signatures align with the observed phenotypes: fewer reactive oxygen species, less DNA damage signaling, and normalized stem cell division. The data processing pipeline relied on established bioinformatics tools, including Fastp for read preprocessing, STAR for alignment, Salmon for transcript quantification, and DESeq2 for differential expression analysis, lending methodological rigor to the pathway-level conclusions.

The broader significance of the work lies in connecting dietary bioactive compounds to a specific stem cell aging mechanism. Intestinal epithelial homeostasis depends on a delicate balance between stem cell self-renewal and differentiation, and oxidative stress tips this balance toward hyperproliferation and barrier failure. By showing that CGA attenuates this redox-driven dysregulation through a CncC-dependent route, the study extends the redox-protective effects of dietary polyphenols from general cytoprotection into the realm of tissue-specific stem cell aging. Because NRF2 is conserved from flies to humans, the findings provide a mechanistic framework that can be tested in mammalian models and, eventually, in human nutrition studies.

Several caveats temper the enthusiasm. The work was conducted entirely in flies, and dose translation from fly food to human diets is far from straightforward. The authors note that their data do not prove direct CncC activation, leaving open the possibility that metabolites, microbiome interactions, or indirect stress-signaling pathways mediate the effect. Moreover, while barrier function improved and autophagic stress responses declined, the long-term consequences of CGA supplementation on lifespan and healthspan in aging animals remain to be fully characterized in this system.

Even so, the study offers a compelling proof of principle that a common dietary molecule can engage an evolutionarily conserved stress-response pathway to preserve stem cell function in an aging organ. As populations worldwide age, interventions that maintain intestinal integrity could have outsized effects on healthy longevity, given the gut’s role in immunity, metabolism, and systemic inflammation. The Korea Food Research Institute team’s findings, supported by the institute’s Main Research Program, suggest that the humble polyphenol in a morning cup of coffee may be doing more than providing antioxidants in the bloodstream; it may be helping to keep the gut’s regenerative engine running smoothly as the years accumulate.

Subject of Research: Chlorogenic acid protection of aging intestinal stem cells via the CncC/NRF2 oxidative stress pathway in Drosophila

Article Title: Oxidative stress-associated intestinal stem cell dysfunction during aging is attenuated by chlorogenic acid in a CncC-dependent manner

Article References: Oxidative stress-associated intestinal stem cell dysfunction during aging is attenuated by chlorogenic acid in a CncC-dependent manner. (n.d.). https://doi.org/10.1007/s11357-026-02586-0

Image Credits: AI Generated

DOI: 10.1007/s11357-026-02586-0

Keywords: chlorogenic acid, intestinal stem cells, oxidative stress, NRF2, CncC, Drosophila, aging, gut barrier, DNA damage response, autophagy, polyphenols, GeroScience

The discovery hinges on a classic piece of neural circuitry: the half-center oscillator. Engineers and neuroscientists have long known that two populations of neurons wired to inhibit each other can generate rhythm from nothing more than mutual antagonism. When one side fires, it suppresses the other; the suppressed side then escapes from inhibition, fires in its turn, and pushes its opponent back down. This arrangement powers the central pattern generators that control swimming, walking and breathing throughout the animal kingdom. The Oxford team has now shown that the same architecture, usually associated with movement, has been repurposed to regulate something as profound as the need for sleep.

To watch this circuit in action, the researchers implanted tiny translucent windows into the heads of living flies and used two-photon microscopy to image the calcium signals of dFBN dendrites over many minutes. What they saw was strikingly regular: fluorescence transients repeating rhythmically at 0.2 to 1 hertz, the frequency band that defines slow-wave activity. Simultaneous whole-cell patch-clamp recordings revealed the electrical events beneath these optical signals. The bistable neurons oscillated between depolarized UP states, during which they fired high-frequency bursts of action potentials, and hyperpolarized DOWN states, during which they fell silent. The alternation was metronome-like, mirroring the UP and DOWN membrane states that cortical neurons occupy during mammalian non-REM sleep.

Crucially, the slow rhythm did not arise from every cell in the ensemble, nor from cell-intrinsic pacemakers acting alone. When the team imaged individual dFBN somata within one hemisphere, their fluorescence traces were, on average, uncorrelated with one another. Instead, a handful of pacemaker-like neurons accounted for most of the variance in the compound dendritic signal. The real source of the rhythm emerged when the researchers imaged both brain hemispheres at once: the left and right dFBN populations oscillated in antiphase, each firing exactly when the other fell silent. Connectomic analysis of two independent electron-microscopy datasets, the hemibrain and FlyWire connectomes, confirmed that dFBNs are linked by dense, reciprocal, and almost perfectly symmetric connections, precisely the wiring diagram a half-center oscillator requires.

The neurotransmitter carrying this cross-hemispheric inhibition turned out to be glutamate, which is unusual because glutamate is best known as the brain’s main excitatory signal. In the fly central nervous system, however, glutamate frequently acts as an inhibitor. The researchers verified this assignment anatomically, using genetic intersection strategies that isolated dFBNs from other glutamatergic neurons, and functionally, with genetically encoded glutamate and acetylcholine sensors. When they optogenetically activated one random half of the dFBN mosaic, the other half hyperpolarized and stopped spiking, and this inhibition persisted in the presence of tetrodotoxin, proving that the connection is monosynaptic. dFBNs, in short, inhibit each other directly through inhibitory glutamatergic synapses.

Was this rhythm actually sufficient to put an animal to sleep? The team answered this with an elegant optogenetic replay experiment. Because stimulating both hemispheres in synchrony can drive the mutually inhibitory neurons into a depolarization block or a stalemate, earlier attempts to activate dFBNs had produced confusing results. Pulsed illumination, which mimics the natural burst structure, worked beautifully. When the researchers drove dFBNs with light patterns that reproduced naturalistic slow-wave activity, 500-millisecond bursts recurring at roughly 0.5 to 1 hertz, the flies went to sleep. The effect scaled with intraburst frequency up to a saturation point of about 40 hertz, matching the peak firing rates observed in spontaneous recordings. Tonic stimulation at the same average rate was far less effective, showing that the temporal structure of the signal, not just its intensity, carries the sleep instruction.

The necessity side of the argument was just as convincing. Depleting the vesicular glutamate transporter from dFBNs, or silencing them with potassium channels, reduced both baseline sleep and the rebound sleep that normally follows deprivation, all without hyperactivity or anatomical defects that might confound the interpretation. Sleep became fragmented, bouts shortened, and the slow oscillations themselves weakened. Interference with glutamatergic transmission thus dissolved both the rhythm and the behavior it was proposed to drive, tying the half-center oscillator directly to the homeostatic regulation of sleep.

Perhaps the most striking finding is that dFBN oscillations do not pause when the fly is awake. In mammals, slow waves are largely confined to deep sleep. In the fly, the team imaged head-fixed animals walking on a spherical treadmill and roused them with brief pulses of infrared heat aimed at the abdomen. The heat triggered dopamine release onto dFBN dendrites, locomotion, and a brief collapse of the calcium oscillations, but the rhythm quickly resumed through a powerful postinhibitory rebound. Slow-wave power in dFBNs rose with the duration of sleep deprivation, grew roughly linearly through the first half of the night, decayed over 12 to 24 hours of recovery, and followed a natural daily rhythm peaking in the evening. The oscillation therefore behaves as a continuous, amplitude-modulated readout of sleep pressure, streaming information about sleep need to downstream circuits even during waking, in a fly-mammalian inversion of convention.

How does the circuit tune its own gain? The answer is a surprising form of synaptic depression. Sleep deprivation is usually assumed to potentiate synapses, and indeed active zone markers like bruchpilot increase in most regions of the sleep-deprived fly brain. dFBNs do the opposite. Using genetic tagging of endogenous bruchpilot, the team showed that dFBN active zones shrink after sleep loss, and direct measurement of optically evoked glutamate release confirmed that transmission from dFBN synapses was attenuated. In a computational model of two reciprocally inhibitory dFBNs embedded in recurrent excitatory circuitry, this weakening was essential. Increased intrinsic excitability and stronger external drive raise slow-wave power only if the output synapses depress in parallel; without that homeostatic brake, the oscillating neurons would smother their own excitatory inputs. Two opposing forces, heightened excitability and weakened output, thus conspire to encode sleep need in the amplitude of the rhythm.

The broader picture is one of elegant engineering. dFBNs inherit their sleep pressure from a biochemical memory described in previous work, in which lipid peroxidation products oxidize the cofactor of the Shaker potassium channel’s Hyperkinetic subunit, one bit at a time. The half-center oscillator now provides the output stage: it converts that slowly accumulating chemical record into a periodic electrical signal whose amplitude tracks sleep need from moment to moment, resists the antagonism of arousing dopaminergic neurons in a flip-flop arrangement reminiscent of the mammalian hypothalamic sleep switch, and, when strong enough, tips the animal into sleep. The remaining puzzle is analog-to-digital conversion: sleep-wake states are binary, while the signal is graded. The authors suggest that strongly facilitating synapses or the winner-take-all architecture of the fan-shaped body could perform the transformation. Whatever the mechanism, the lesson is clear: the same rhythmic circuits that make legs move and hearts beat have been conscripted, over evolutionary time, to make brains rest.

Subject of Research: A half-center oscillator in Drosophila sleep-control neurons that generates slow-wave activity encoding and regulating sleep pressure

Article Title: A half-center oscillator regulates sleep pressure

Article References: A half-center oscillator regulates sleep pressure. (n.d.). https://doi.org/10.1038/s41593-026-02431-9

Image Credits: AI Generated

DOI: 10.1038/s41593-026-02431-9

Keywords: sleep pressure, half-center oscillator, slow-wave activity, Drosophila, dorsal fan-shaped body, glutamatergic transmission, optogenetics, sleep homeostasis, synaptic depression, two-photon imaging, connectomics, neural oscillations

The study began with a large-scale forward genetic screen. Using ethyl methanesulfonate mutagenesis on Drosophila chromosome 3L and the ey-FLP-based mosaic analysis with a repressible cell marker (MACRM) system, the researchers induced homozygous mutant clones in cells already carrying oncogenic Ras (RasV12), then searched for recessive-lethal alleles that synergized with Ras to drive malignant overgrowth of the eye-antennal disc. Eight previously uncharacterized tumor suppressors emerged: the endocytic genes Vacuolar protein sorting 36 (Vps36), Syntaxin 7 (Syx7), Rabaptin-5-associated exchange factor (Rabex-5), and Tumor susceptibility gene 101 (TSG101), plus furry (fry), fiery mountain (fmt), emei, and misshapen (msn). Together with the canonical polarity tumor suppressors scribble (scrib) and lethal (2) giant larvae (l(2)gl), these genes defined a cohort of ten genetically distinct Ras-driven tumor models.

Each of the ten models was then tracked longitudinally through three time points—5.5, 9.5, and 13.5 days after egg laying—using four quantitative malignancy metrics: larval tumor burden (measured by GFP signal and tumor-to-body ratio), tumor overgrowth (volumetric analysis of disc tissue), tumor-mediated cachexia (larval transparency reflecting muscle and fat body degradation), and invasion of the neighboring ventral nerve cord. The resulting atlas revealed three phenotypic stages shared by all tumors: an initial stage marked by cell overgrowth, a promotion stage characterized by uncontrolled proliferation, onset of invasion, and early cachexia, and a progression stage distinguished by severe wasting and aggressive tissue invasion. Notably, the researchers also observed intestinal metastasis in larvae bearing Ras-driven tumors, indicating genuine malignant potential beyond local overgrowth.

Although all ten tumors ultimately developed aggressive phenotypes, their progression trajectories diverged. To capture this heterogeneity, the team applied robust linear regression to six digitized phenotypic parameters, extracting the intercept (initial malignancy), slope (progression rate), and adjusted R-squared (goodness of fit) of each regression model. Principal component analysis projected the ten models onto a two-dimensional map in which PC1 captured features associated with cachexia and PC2 reflected tumor burden. K-means clustering then classified the tumors into three subtypes: Group A (scrib, l(2)gl, Vps36, fry, emei, fmt), Group B (Syx7, msn), and Group C (TSG101, Rabex-5). This phenotype-centric stratification—rather than the gene-centric approach typical of longitudinal cancer studies—became the analytical backbone of the entire platform.

Bulk RNA sequencing at five pseudotime points (T1, wild-type tissue; T2, benign RasV12; T3, initial; T4, promotion; T5, progression) generated longitudinal transcriptomes for each subtype. Weighted gene co-expression network analysis (WGCNA) linked gene modules to the phenotypic traits, Mfuzz soft clustering delineated continuously upregulated and downregulated gene clusters, and PANGEA functional annotation identified the biological processes and signaling pathways significantly associated with malignant progression. All three subtypes shared enrichment for glycolysis, gluconeogenesis, and amino acid metabolism, and for the EGFR/FGFR/PvR MAPK-related pathway. Group B uniquely enriched fatty acid oxidation and the Hippo pathway, while Group C showed inositol phosphate metabolism, O-glycan biosynthesis, and TGFβ/Activin signaling. Transcription factor enrichment identified the Notch-related factor longitudinals lacking (lola) and the AP-1 components Jun-related antigen (Jra) and kayak (kay) as co-enriched across groups, while protein interaction networks pinpointed metabolic hub genes including Got2, Pgi, and Hex-A in at least two subtypes.

Comparing malignant tumors at T3 with benign RasV12 tumors at T2 revealed 247 co-upregulated and 578 co-downregulated genes, annotated primarily to JAK/STAT, NF-κB/Toll, and MAPK signaling. Gene set variation analysis and single-sample gene set enrichment analysis confirmed widespread activation of JAK/STAT and MAPK pathways from T3 onward, and immunofluorescent staining showed increased phosphorylation of the MAPK effectors rolled (ERK) and basket (JNK), elevated JNK targets MMP1 and wingless, and consistently raised levels of the NF-κB/Toll transcription factor Dorsal across all ten models. Notch signaling scores correlated positively with tumor progression, whereas Hippo activation correlated inversely with severity. Staining confirmed robust upregulation of the Notch ligand Delta, the Notch intracellular domain, its target dMyc, and the Hippo target Diap1, together with increased nuclear translocation of the Hippo co-factor Yorkie.

Functional validation followed. Expressing constitutively active Notch (Notchact) synergized with loss of scrib, l(2)gl, Vps36, or fry to drive aggressive overgrowth, but failed to promote expansion in Syx7-, Rabex-5-, or TSG101-deficient cells—a context-dependent interaction the authors attribute to differences among endocytic processes. Activated Yorkie (YkiS168A), by contrast, cooperated with seven of the tumor suppressor losses. The fry gene emerged as a particularly potent suppressor: its 3,479-amino acid product functions with the NDR kinase tricornered and Mob as tumor suppressor (mats) to regulate polarized cell growth, and mammalian studies show FRY depletion promotes nuclear localization of YAP/TAZ. Because fry-deficient cells cooperated with multiple oncogenic inputs (RasV12, Notchact, YkiS168A), the team selected RasV12; fry tumors—a previously uncharacterized model—for deep multi-omics analysis combining bulk RNA-seq and ATAC-seq across tumor stages.

The integrative analysis of RasV12; fry tumors identified dynamic transcriptional modules enriched for MAPK, NF-κB/Toll, Notch, and Hippo signaling, with stage-specific expression peaks: Toll, mastermind, Diap1, frizzled, and wingless peaked at the initial stage, while insulin pathway genes rose at later stages coinciding with severe cachexia and invasion. ATAC-seq confirmed elevated chromatin accessibility at promoters of key effectors in all four pathways, with motif enrichment for AP-1, DREF, and Initiator binding sites. Genetic perturbations then established necessity: RNAi or dominant-negative inhibition of JNK components (Tak1, hemipterous, basket, kayak, Jra), suppression of Toll and Dif, blockade of Notch ligands and receptor, and overexpression of warts to reactivate Hippo each markedly shrank the GFP-marked tumor region and rescued the pupariation delay in tumor-bearing larvae. Under physiological conditions, fry knockdown left JNK-dependent thorax closure unaffected but enlarged the adult eye and rescued the eiger-induced small-eye phenotype, indicating that fry modulates JNK-dependent processes specifically in pathological contexts.

Translational analyses then connected the fly models to human oncology. Using fourteen orthology databases, the ten Drosophila tumor suppressors were mapped to eighteen human orthologs, including SCRIB, LLGL1/LLGL2, VPS36, STX7/STX12, RABGEF1, TSG101, FRY/FRYL, PPP6R1-3, TMEM161A/B, and MINK1/TNIK/MAP4K4. Pan-cancer evaluation of TCGA data showed that SCRIB is mutated in more than 10% of pancreatic, esophageal, endometrial, uterine carcinosarcoma, and melanoma cases; LLGL1/LLGL2 shows the highest mutation rates in endometrial carcinoma and melanoma; endocytic genes are frequently mutated and downregulated in endometrial cancer and melanoma; and FRY/FRYL mutations exceed 5% in most KRAS/NRAS-driven cancers, with FRY consistently downregulated. Single ortholog mutations significantly affected patient survival—SCRIB mutations threatened overall and disease-free survival in pancreatic adenocarcinoma, and FRY mutations adversely affected survival in esophageal carcinoma—while expression levels correlated positively with overall survival across multiple cancers.

Cross-species validation at single-cell resolution sealed the argument. The team integrated publicly available single-cell datasets from colorectal, lung, pancreatic, and melanoma patients, retaining 174,385 high-quality cells, and scored pathway activity in malignant epithelial cells. Within RAS-activated subclusters, RAS signaling correlated positively with MAPK, JNK, Toll-like receptor, and Notch activation and with Hippo inactivation in nearly all cancers—an activation pattern directly mirroring RasV12; fry tumors. A composite fry/FRY-deficient tumor signature, summarizing JNK, TLR, and Notch activation with Hippo inactivation, correlated with cell proliferation, epithelial-mesenchymal transition, and cell migration across cancers, and low FRY expression was associated with altered immune infiltration, including increased CD8 T cells and decreased M2 macrophages. Finally, machine learning models built from the conserved pathway components—117 algorithm combinations evaluated for one-, three-, and five-year survival prediction—performed excellently for lung adenocarcinoma, pancreatic adenocarcinoma, and melanoma (AUC values above 0.85), with a StepCox[both] + random survival forest model effectively stratifying LUAD and melanoma patients into high- and low-risk groups. The authors acknowledge that the fly lacks adaptive immunity and that the precise molecular scaffolds mediating the four-pathway crosstalk remain undefined; future work will use immunoprecipitation-mass spectrometry to identify FRY-interacting proteins and validate the findings in patient-derived organoids. Even so, ART-D demonstrates that evolutionarily ancient oncogenic mechanisms, first dissected in a fruit fly eye disc, can be translated into diagnostic and prognostic tools for some of the deadliest RAS-driven human malignancies.

Subject of Research: Cross-species oncogenic mechanisms uncovered by the Drosophila ART-D atlas of Ras-driven tumors

Article Title: Cross-species insights from ART-D to uncover evolutionarily conserved oncogenic mechanisms

Article References: Guo, Y., Zheng, J., Wu, Y., Zhao, K., Lv, D., Liu, W., Wang, M., Lu, J.-Y., Xu, W., Wang, X., & Ma, X. (2026). Cross-species insights from ART-D to uncover evolutionarily conserved oncogenic mechanisms. Molecular Systems Biology, 22(8), 1214-1251. https://doi.org/10.1038/s44320-026-00215-8

Image Credits: AI Generated

DOI: 10.1038/s44320-026-00215-8

Keywords: Drosophila, RAS oncogene, ART-D, tumor suppressors, JNK signaling, Notch pathway, NF-κB/Toll, Hippo pathway, furry, cross-species cancer research, machine learning prognosis, KRAS

The study began with a deceptively simple question: which genes, when silenced in the fat body, change the growth of organs elsewhere in the animal? Answering it required a screening system that could measure growth in living larvae rather than relying on laborious dissection and imaging. The team engineered a reporter line, dubbed GQ, in which the fat body drives genetic knockdowns while the growth response is read out in peripheral tissues, specifically the imaginal discs, the larval structures that will eventually form adult wings, legs, and eyes. These discs carry a firefly luciferase reporter whose activity scales with tissue growth, while a Renilla luciferase reporter provides an internal reference. By homogenizing individual larvae at a standardized developmental time point, 115 hours after egg deposition, and running dual luciferase assays, the researchers could quantify the growth consequences of each fat-body-specific gene knockdown in a single, rapid measurement.

Using RNA interference lines from the Vienna Drosophila Resource Center, the team systematically knocked down secreted and secretory-pathway genes in the fat body and scored the resulting effects on imaginal disc growth. The primary screen flagged dozens of candidate genes, and a rigorous secondary screen retested each hit with multiple independent RNAi transgenes, including lines from the Bloomington stock center and the National Institute of Genetics in Japan. Only candidates whose effects could be reproduced with independent reagents were considered genuine. Out of the retested genes, 32 were confirmed with high confidence, three showed moderate effects, and 13 failed validation, a sobering reminder of why independent confirmation is essential in genetic screens. Among the confirmed hits, one protein stood out for both the strength of its effect and the elegance of its mechanism: SPARC, short for Secreted Protein Acidic and Rich in Cysteine, also known as BM-40.

SPARC is a matricellular protein, meaning it is secreted into the extracellular environment but does not serve as a structural component of the matrix itself. Instead, matricellular proteins modulate cell-matrix interactions and cell signaling. In mammals, SPARC has been implicated in tissue remodeling, wound repair, fibrosis, and cancer biology, but its role as an endocrine growth regulator had not been established. The new work shows that when SPARC production is reduced in the larval fat body, the entire animal grows less. Adult flies with fat-body SPARC knockdown emerge smaller, with reduced body weight and smaller wings, effects that were quantified by measuring adult dry weight and wing area across multiple independent experiments and temperatures. The consistency of the size reduction across different driver lines and RNAi constructs pointed to a genuine developmental function rather than a technical artifact.

The critical question was how a protein secreted from the fat body could slow the growth of tissues it never touches directly. The answer lies in a small cluster of neurosecretory cells in the larval brain called the insulin-producing cells, or IPCs. These cells are the functional counterparts of human pancreatic beta cells: they release Drosophila insulin-like peptides, particularly Ilp2, into the circulation, and circulating insulin activates the insulin signaling pathway in target tissues, driving cell growth and proliferation. When the researchers examined the IPCs of larvae in which the fat body had been depleted of SPARC, they found that Ilp2 accumulated inside the cells instead of being released. In other words, the peptide was being made but retained, a classic secretory defect. Fat-body SPARC, it appears, is required for the proper endocrine release of insulin from the brain, acting as an incretin-like signal that promotes insulin secretion in response to nutritional conditions.

Several control experiments strengthened this interpretation. A short, one-day depletion of SPARC did not grossly disrupt larval feeding behavior or fat body integrity, arguing against the possibility that the growth defects were secondary to starvation or tissue damage. Larvae with SPARC knockdown still ingested food normally, as shown by feeding assays with dye-labeled yeast paste, and their fat body architecture, visualized with nuclear and membrane stains, remained intact. The team also showed that SPARC is indeed secreted into the hemolymph, the insect circulatory fluid, where it can be detected by western blotting, and that its expression responds to nutritional state, with starvation reducing SPARC mRNA levels in the fat body. These observations fit a model in which the fat body, upon sensing adequate nutrition, secretes SPARC into the circulation, and SPARC in turn stimulates the IPCs to release Ilp2, thereby licensing systemic growth.

Perhaps the most striking result of the study is its evolutionary punchline. When the researchers supplied synthetic human SPARC to fly larvae lacking their own SPARC, the human protein could substitute for the fly version, restoring insulin release and growth. This cross-species rescue demonstrates that the biochemical function of SPARC in this signaling axis has been conserved over hundreds of millions of years of evolution separating insects and vertebrates. It also raises an obvious and tantalizing question for mammalian biology: could SPARC play a comparable role in human insulin regulation? Mammalian incretins, such as GLP-1, are gut-derived hormones that potentiate insulin secretion from pancreatic beta cells, and they form the basis of a major class of diabetes drugs. A fat-derived, SPARC-dependent pathway that promotes insulin release would represent a fundamentally new branch of this regulatory logic, though the authors are careful to frame the human implications as a hypothesis for future work rather than a demonstrated mechanism.

The technical achievement behind the discovery deserves attention in its own right. Traditional genetic screens for growth regulators require laborious measurements of organ size, often by microscopy, which limits throughput and introduces variability. By coupling a tissue-specific knockdown system to a luciferase-based growth readout, the Würzburg team created a pipeline in which a single larva yields a quantitative growth measurement in a plate reader. The dual-reporter design, with firefly luciferase reporting imaginal disc growth and Renilla luciferase normalizing for larval size and handling differences, allowed hundreds of genotypes to be assayed individually. The supplementary data accompanying the paper document the full trajectory of the screen, from the primary results across the tested lines to the validation tables listing every independent transgene and its effect, providing an unusually transparent record of how the conclusions were reached.

Beyond SPARC itself, the study delivers a conceptual message about how growth is coordinated across an animal. The fat body is not merely a passive energy depot; it is an endocrine gland whose secreted products reach into the brain and tune the output of the insulin-producing cells. This architecture mirrors the inter-organ communication circuits of mammals, in which the liver, adipose tissue, gut, and pancreas exchange hormonal signals to match growth and metabolism to nutrient availability. Disruptions in such circuits are central to metabolic disease, and understanding their components in a genetically tractable organism like Drosophila provides a framework for dissecting the corresponding human pathways. The identification of SPARC as an incretin-like, insulin-promoting signal adds a new name to the roster of conserved growth regulators and suggests that the extracellular matrix, long viewed as structural scaffolding, participates directly in endocrine control.

Future experiments will need to determine exactly how SPARC acts on the IPCs, whether it binds a specific receptor on these cells, modulates their secretory machinery, or acts through intermediate signals in the hemolymph. It will also be important to establish whether the SPARC-dependent pathway responds to specific nutrients and how it integrates with other known fat-body-derived signals that influence insulin release and growth. For now, the study stands as a vivid example of modern genetics at work: a systematic in vivo screen, a rigorous validation pipeline, and a mechanistic story that connects a secreted matrix protein in the fat body to insulin granules in the brain and, ultimately, to the size of the adult fly. In doing so, it transforms our picture of how a growing animal counts its calories and converts them into body mass, and it plants a flag for SPARC in a territory where few would have thought to look.

Subject of Research: Fat body-derived SPARC signaling in the regulation of insulin release and systemic larval growth in Drosophila

Article Title: Fat body secreted SPARC promotes Ilp2 release and systemic growth in Drosophila larvae

Article References: Fat body secreted SPARC promotes Ilp2 release and systemic growth in Drosophila larvae. (n.d.). https://doi.org/10.1186/s12915-026-02761-x

Image Credits: AI Generated

DOI: 10.1186/s12915-026-02761-x

Keywords: Drosophila, SPARC, insulin signaling, fat body, Ilp2, incretin, larval growth, inter-organ communication, genetic screen, nutrient signaling, insulin-producing cells, BMC Biology

The study, published in Nature Metabolism, followed 25 healthy young men who performed 45 minutes of moderate-intensity cycling at roughly 75 percent of their maximum heart rate. The researchers collected blood, saliva and urine samples before exercise and at multiple timepoints afterwards, spanning from immediately post-exercise to a full 24 hours of recovery. Using a combination of mass spectrometry for saliva and urine and the Olink Explore HT affinity-based platform for plasma, they quantified 10,128 proteins in total. Of these, 3,007 — about 30 percent — were significantly regulated by the single exercise session, each following its own fluid-specific and time-specific trajectory.

The technical design of the study was critical to its power. Frequent sampling at approximately 0, 0.5, 1, 3 and 24 hours after exercise allowed the team to resolve temporal dynamics that coarser studies would miss. To confirm that the exercise protocol produced genuine physiological effects, the researchers measured canonical metabolic and inflammatory markers. Glucose, insulin and C-peptide rose immediately after exercise and then overcorrected below baseline between half an hour and three hours later, while the cytokines IL-6 and IL-10 showed a delayed but sustained elevation before returning to baseline by three hours. These time courses reproduced the well-established acute exercise response, validating the platform before any novel discoveries were made.

Each body fluid told a strikingly different story. Plasma, the primary conduit for inter-organ communication, exhibited a dramatic spike in protein regulation immediately after exercise, with 2,156 unique proteins — 40 percent of the quantified plasma proteome — showing significant time effects, followed by rapid normalization. Saliva, by contrast, displayed sustained bidirectional changes that persisted through the entire 24-hour recovery period, affecting 601 proteins, or 31 percent of the salivary proteome. Urine showed a more modest and transient response, with 272 regulated proteins that resolved completely by 24 hours. Despite these divergent dynamics, 297 proteins were altered in at least two fluids simultaneously, and seven changed in all three, hinting at a coordinated systemic response that transcends compartmental boundaries.

The salivary findings were particularly unexpected. Saliva is rarely considered in exercise omics studies, yet the analysis revealed that exercise-responsive salivary proteins originated from salivary glands, liver, bone marrow and lymphoid tissues, reflecting both local glandular secretion and systemic endocrine signals. One cluster of proteins, elevated and sustained through 24 hours, was strongly enriched for associations with metabolic disease: 52 of 145 unique proteins in this cluster were linked to type 2 diabetes risk in the UK Biobank protein-disease atlas. Notably, 132 FDA-approved drug targets were identified in the salivary proteome, 41 of which were exercise-responsive, suggesting that acute exercise transiently modulates pathways that are chronically dysregulated in diabetes.

Urine told a complementary story about kidney function and cellular turnover. Proteins that decreased after exercise were associated with keratinization and elastic fibre formation and originated from epithelial cells, consistent with increased filtration of cellular shedding by-products. Proteins that increased were linked to signal transduction and iron uptake, with enrichment for hepatocytes and distal nephron segments. Unlike saliva, urinary exercise-responsive proteins were not enriched for classically secreted proteins, indicating they arose from cellular shedding or tubular secretion rather than active endocrine signalling. This suggests the kidneys act as a filtering window on exercise-induced tissue remodelling, sympathetic activity and altered blood flow.

To understand how these compartments coordinate, the researchers built protein-protein correlation networks across fluids. Immediately after exercise, network connectivity expanded by roughly 1.7-fold relative to pre-exercise, with vesicle-associated proteins such as CD63 and TSG101 and integrin-linked cytoskeletal regulators forming highly connected hubs. By one hour, modules shifted toward cellular stress responses and translation activation; by three hours, toward metabolic and endocrine regulation; and by 24 hours, toward immune cell mobilization, growth factor activity and tissue repair. Throughout all timepoints, extracellular matrix remodelling proteins — including collagens, SPARC and fibulin family members — remained centrally positioned, indicating that structural reorganization is a persistent backbone of the exercise response.

Replication in an independent cohort of 24 middle-aged adults, 62.5 percent of them women, performing aerobic, high-intensity interval and resistance exercise in a randomized crossover design confirmed the generality of the findings. Despite differences in age, sex and exercise modality, 1,212 proteins — 56 percent of those regulated in the discovery cohort — responded consistently, and 74 percent of all time-responsive proteins showed concordant direction of effect immediately post-exercise. Only two proteins exhibited a modality-by-time interaction, while 804 showed a main effect of modality, indicating that exercise type influences response magnitude rather than direction for most proteins. The acute stress response appears universal, while recovery trajectories become increasingly personalized with age, sex and training mode.

The team then integrated human genetics to ask which exercise-responsive proteins matter for disease. Using colocalization analysis from the Open Targets Platform, which identifies loci where protein abundance signals and disease signals arise from the same genetic variant, they constructed networks linking secreted exerkines to health traits. Cardiometabolic diseases emerged as central hub nodes, with proteins such as FGF5, FURIN and COL4A1 converging on cardiovascular outcomes and KLK13, CTSF and PAM on metabolic health. Crucially, 69 of the colocalized secreted exercise-regulated proteins are targets of FDA-approved drugs, offering tangible starting points for exercise-mimetic therapeutics for people unable to exercise — though the authors caution that no single drug can recapitulate the full systemic benefits of physical activity.

Finally, the researchers functionally validated prioritized candidates in fruit flies, using muscle-specific RNAi knockdown of Drosophila orthologues of human exerkines. The results were striking: knockdown of PDGF, TNF or FGF orthologues impaired training-induced endurance adaptation without affecting naive performance, while myostatin knockdown enhanced baseline endurance but abolished further training gains. GDF15 and BMP4 knockdown increased endurance across conditions, and several knockdowns altered sleep, feeding behaviour and whole-body lipid storage after chronic training. These experiments demonstrate that exercise-responsive human plasma proteins are not passive biomarkers but conserved, muscle-derived regulators of exercise adaptation, behaviour and metabolism. The complete atlas has been released as an open-access interactive resource, providing a foundation for precision exercise prescription, biomarker development and the rational design of therapies that activate exercise-responsive pathways.

Subject of Research: Multi-fluid proteomic responses to acute exercise and their genetic links to cardiometabolic disease

Article Title: Systemic proteomic dynamics of acute exercise reveal genetic links to health and disease

Article References: Systemic proteomic dynamics of acute exercise reveal genetic links to health and disease. (n.d.). https://doi.org/10.1038/s42255-026-01621-w

Image Credits: AI Generated

DOI: 10.1038/s42255-026-01621-w

Keywords: exercise, proteomics, exerkines, plasma, saliva, urine, metabolism, type 2 diabetes, cardiometabolic disease, GWAS colocalization, Drosophila, skeletal muscle

The work builds on the group’s earlier discovery that adult flies whose larvae were raised alongside certain bacteria reject food laced with peptidoglycan, a core component of bacterial cell walls. Flies reared in germ-free conditions, by contrast, happily extend their proboscis toward sucrose solutions containing peptidoglycan, even though their taste system remains fully functional for other aversive compounds such as caffeine. Intriguingly, only some bacterial species could restore this sensitivity in germ-free larvae: the pathobiont Levilactobacillus brevis succeeded, while the symbiont Lactiplantibacillus plantarum failed. Two questions therefore loomed. What bacterial molecule carries the priming signal, and which host cells and proteins receive and transmit it?

To answer the first question, the researchers exploited a mono-association protocol in which sterilized eggs are deposited onto food containing a chosen bacterial strain or chemical, and the adults that later emerge are tested with the proboscis extension reflex, a standard readout of gustatory response. Live L. brevis primed the larvae, but heat-killed bacteria and bacterial supernatant did not, indicating that a living metabolic process was at work. A clue came from earlier studies showing that bacterial uracil metabolism governs the transition from harmless commensal to damaging pathogen in the fly gut. When the team turned to Erwinia carotovora, a bacterium for which uracil-metabolism mutants were already available, the picture sharpened dramatically. Two mutant strains unable to release uracil lost the ability to prime larvae, while simply adding purified uracil at a concentration of one millimolar to the food was sufficient to trigger priming in completely germ-free animals. Cytosine and thymine, close chemical relatives of uracil, could not do the same, underscoring the specificity of the signal.

Timing proved equally critical. The team had previously identified a developmental window between egg laying and 48 hours after oviposition during which bacterial exposure must occur. The new experiments narrowed this window further: larvae exposed to uracil only 24 hours after hatching failed to acquire the primed state, confirming that the earliest moments of larval life are decisive. Calcium imaging of adult proboscis neurons later revealed the cellular consequence. The ppk23-expressing taste neurons that directly detect peptidoglycan in adult flies responded robustly to the bacterial molecule only in animals whose larvae had encountered uracil, demonstrating that the larval experience genuinely alters neuronal responsiveness in adulthood rather than merely changing gross behavior.

With the bacterial cue identified, attention turned to the host machinery. Prior research had established that uracil activates the enzyme Duox in the Drosophila intestine, triggering production of reactive oxygen species that attack invading pathobionts. The team tested whether the same pathway underlies priming. Using RNA interference to reduce Duox specifically in enterocytes, the absorptive cells of the gut lining, they abolished the adult aversion to peptidoglycan. A temperature-sensitive genetic switch allowed them to silence Duox at precise life stages: blocking the enzyme during larval development suppressed priming, while blocking it in adults had no effect. Direct biochemical measurements confirmed that hydrogen peroxide accumulates in larvae within 24 hours of uracil exposure, and that this signal disappears when catalase, the hydrogen peroxide-degrading enzyme, is overexpressed in gut cells or when the antioxidant vitamin C is added to the food.

Yet reactive oxygen species alone could not reproduce the effect. Supplementing larvae with hydrogen peroxide at several concentrations and exposure schedules failed to prime them, even though vitamin C reliably blocked priming when bacteria or uracil were present. This paradox suggests that the spatially and temporally precise burst of ROS generated inside the gut lumen matters in ways that global exposure cannot mimic. One attractive hypothesis, which the authors discuss, is that locally produced ROS oxidize lipids or other biomolecules to form reactive electrophilic metabolites. In vertebrates, lipid peroxidation products such as 4-hydroxynonenal are known activators of TRPA1 channels, which sense oxidative stress through covalent modification of conserved cysteine residues. Whether a similar chemistry operates in the fly intestine remains to be demonstrated, but it would elegantly explain why uracil works while exogenous hydrogen peroxide does not.

The next step was to find the receptor that senses the ROS signal. The fly’s TrpA1 ion channel, an ortholog of the mammalian pain and irritant sensor TRPA1, is activated by heat, reactive oxygen species, ultraviolet light and irritating chemicals, and exists as five alternatively spliced isoforms. Using knock-in flies expressing single isoforms and knock-out flies lacking specific combinations, the researchers showed that isoforms B, C and E, but not A or D, are competent to mediate priming. Mapping the expression patterns of these isoforms revealed a striking convergence: all three are co-expressed in a single isolated neuron at the very front of the larva, within the terminal organ, a peripheral sensory structure. This neuron also expresses Gr66a, a marker of bitter-sensing gustatory neurons. Silencing TrpA1 in these cells during the larval stage, but not the adult stage, abolished priming, and restoring TrpA1-B expression in Gr66a-positive neurons of otherwise TrpA1-deficient flies fully rescued the phenotype. TrpA1-A could not substitute, proving that the isoforms are not interchangeable for this function.

Calcium imaging then connected the pieces. When larvae expressing the calcium indicator GCaMP were stimulated with hydrogen peroxide, exactly one of the three anterior Gr66a-positive neurons responded strongly, and it was the same neuron that responded to quinine, a bitter compound. The TrpA1-B-positive terminal organ neuron was likewise activated by hydrogen peroxide, and this response vanished when TrpA1 was knocked down in that cell. Most remarkably, the team showed that medium in which uracil-treated larvae had been incubated could activate TrpA1-B-positive neurons in completely naive recipient larvae, and that this activity disappeared when Duox was silenced in the donor larvae’s enterocytes. This implies that a diffusible, Duox-dependent signal, likely hydrogen peroxide or a derivative, is released from the gut into the environment, where it can act at a distance. Such a mechanism raises the tantalizing possibility that infected larvae broadcast information about microbial presence to nearby conspecifics, potentially shaping behavior at the population level.

Finally, the team confirmed that the phenomenon extends beyond the laboratory confines of the proboscis extension reflex. In a two-choice free-feeding assay using 96-well plates of colored agar, female flies allowed to roam and feed freely strongly preferred plain sucrose over sucrose mixed with peptidoglycan, with preference indices exceeding 0.8. Flies raised on antibiotics throughout larval life, and TrpA1 knock-out mutants, particularly those lacking isoforms B, C and E, lost this discrimination and consumed both foods indiscriminately. The findings establish a complete signaling arc: bacteria release uracil, uracil triggers Duox-dependent ROS production in the larval gut, ROS activate a single TrpA1-B-positive terminal organ neuron, and the experience is somehow carried across the wholesale destruction and rebuilding of metamorphosis to endow the adult taste system with sensitivity to bacterial peptidoglycan. How that memory survives the radical remodeling of larval tissues and circuits remains the study’s central open question, with candidates ranging from persistent neural circuits and re-specified neurons to epigenetic marks and distributed transcriptional states. Whatever the answer proves to be, the work makes clear that the foundations of what an adult animal can taste are laid, quite literally, in the microbial company it keeps as a child.

Subject of Research: How larval gut exposure to bacterial uracil primes adult Drosophila gustatory aversion to peptidoglycan via Duox-dependent ROS and TrpA1-B neuron signaling

Article Title: Uracil-driven ROS signaling and larval TrpA1-B neuron activation are required for priming the adult Drosophila gustatory response to bacteria

Article References: Milleville, R., Manière, G., Berthelot-Grosjean, M., Lamotte, O., Grosjean, Y., Royet, J., & Kurz, C. L. (2026). Uracil-driven ROS signaling and larval TrpA1-B neuron activation are required for priming the adult Drosophila gustatory response to bacteria. PLOS Biology, 24(10), e3004042. https://doi.org/10.1371/journal.pbio.3004042

Image Credits: AI Generated

DOI: 10.1371/journal.pbio.3004042

Keywords: Drosophila, uracil, reactive oxygen species, Duox, TrpA1, gustatory neurons, peptidoglycan, larval priming, microbiota, terminal organ, gut immunity, sensory plasticity