The Golgi apparatus is best known as the processing and dispatch center of the secretory pathway. Proteins manufactured in the endoplasmic reticulum pass through its stacked membrane cisternae, where they are chemically modified, most notably through glycosylation, the attachment of sugar chains, and then sorted to their correct destinations, whether the plasma membrane, secretory vesicles, or lysosomes. The organelle also manufactures key lipids such as sphingomyelin and glycosphingolipids, participates in autophagosome formation, and runs its own quality-control degradation pathways. In other words, the Golgi sits at the crossroads of protein and lipid homeostasis, which is precisely why its failure could ripple through nearly every cellular process implicated in neurodegeneration.

That failure is not hypothetical. Postmortem studies of Alzheimer’s brains have long revealed fragmented, atrophied Golgi structures in affected neurons. More strikingly, when researchers expressed the amyloid precursor protein Swedish mutant in cells, the Golgi fragmented, and restoring Golgi architecture by expressing the structural proteins GRASP65 and GRASP55 dramatically reduced amyloid-beta production. In induced pluripotent stem cell-derived neurons from patients with sporadic Alzheimer’s disease, the fragmented Golgi phenotype persisted and, crucially, appeared before amyloid and tau pathology developed, suggesting that Golgi breakdown may be one of the earliest cellular events in the disease rather than a late consequence of it.

The strongest new argument for the Golgi’s relevance comes from large-scale human data. When the authors surveyed genetic studies, a striking pattern emerged: multiple independent analyses keep nominating Golgi-related genes as Alzheimer’s risk factors. An RNA-sequencing analysis found that Golgi-related gene ontology terms were elevated both in patients and in people with high polygenic risk scores for the disease, particularly in the temporal cortex. An X-chromosome-wide association study identified SLC9A7, a sodium/proton exchanger concentrated in the trans-Golgi network that maintains the organelle’s acidity, as the only genome-wide significant risk locus. Because Golgi luminal pH governs protein modification, glycosylation, and trafficking, its disruption could derail amyloid precursor protein processing among many other consequences.

Other risk genes reinforce the same theme. SORL1 and SORCS1, both well-established genetic risk factors, encode sortilin-family receptors that shepherd the amyloid precursor protein back to the trans-Golgi network, keeping it away from the endosomes where amyloidogenic cleavage predominates. Adaptor protein 4 complex genes AP4M1 and AP4E1, flagged by enhancer mapping of genome-wide association loci, regulate the precursor protein’s delivery to endosomes. A protective variant in NSF, a gene essential for Golgi reassembly and vesicle fusion, was identified in whole-exome sequencing of patients lacking the ApoE4 allele, hinting that Golgi integrity itself may confer resilience. Machine learning analysis of European GWAS data proposed COG7, a subunit of the complex that maintains Golgi structure and glycosylation, as a new risk gene, and multiancestry proteomic analyses independently nominated COG7, the trans-Golgi metalloprotease CPD, and the retrograde trafficking proteins SNX1, SNX32, and STX6 as candidate causal proteins.

Proteomics adds a second layer of evidence. A landmark 2022 study of more than 500 human brain samples found that Golgi and protein transport module signatures were reduced in asymptomatic Alzheimer’s brains and diminished further in symptomatic cases, correlating with cognitive scores. Perhaps most intriguingly, the extracellular matrix protein repertoire, the matrisome, showed the most prominent proteomic changes in the disease that were invisible at the RNA level, implying that post-translational modifications are the real driver. Since matrix proteins such as proteoglycans and collagen are extensively processed and glycosylated within the Golgi before secretion, Golgi dysfunction offers a mechanistically coherent explanation for this transcriptome-proteome discordance, and matrisome proteins are known to colocalize with amyloid plaques.

A 2024 glycomics study sharpened the picture further by mapping the N-glycan landscape of Alzheimer’s brains. The most altered sugar structures, sialylated and highly branched forms, are built inside the Golgi, and the affected glycoproteins clustered at synapses and the cell surface. Glycoform signatures tied to disease status involved L1CAM and NPTX1, markers of synaptic plasticity and synaptic loss, as well as ATP1B1, a subunit of the sodium-potassium pump essential for neural signaling. Expression of several Golgi-resident glycosylation enzymes, including MAN2A1, MGAT1, and members of the B3GALT, B4GALT, ST6GAL, and ST8SIA families, was altered across multiple brain regions, consistent with a systematic breakdown of Golgi-dependent protein modification that could directly undermine synapses.

Lipid biology supplies a third pillar. The Golgi is the primary site of ceramide processing through glucosylceramide synthase, whose levels fall in Alzheimer’s brains in correlation with ceramide accumulation, a lipid that promotes amyloid-beta production, oxidative stress, and neuronal death. The Golgi-localized enzyme neutral sphingomyelinase 2 drives the secretion of extracellular vesicles that can spread pathological tau between cells; inhibiting it reduced tau propagation and neurodegeneration in mouse models, and neuronal deletion of the gene reduced amyloid-beta production. Meanwhile, the oxysterol-binding protein OSBP1, which exchanges cholesterol and PI4P between the trans-Golgi network and the endoplasmic reticulum at membrane contact sites, regulates cholesterol distribution, mitochondrial fission, and retrograde trafficking, and its knockdown increased amyloidogenic processing of the amyloid precursor protein, linking Golgi-managed cholesterol homeostasis directly to plaque biology.

The authors synthesize these threads into four candidate pathogenic mechanisms. First, Golgi fragmentation may disrupt the normal segregation of the amyloid precursor protein and its processing enzymes, increasing their contact and boosting amyloid-beta generation, possibly even within the Golgi itself. Second, impaired trafficking between the Golgi and the endolysosomal system would trap the precursor protein in endosomes while starving lysosomes of properly sorted enzymes, simultaneously raising amyloid production and lowering its clearance. Third, defective glycosylation would alter countless proteins, including the amyloid precursor protein itself, whose O-glycosylation influences its trafficking and cleavage. Fourth, lipid dyshomeostasis would feed back on Golgi membrane integrity, creating a self-reinforcing vicious cycle that also damages mitochondria and the endoplasmic reticulum. Upstream triggers, including aging, DNA damage, oxidative stress, and neuronal hyperexcitability, as well as amyloid-beta and tau themselves, can all induce Golgi fragmentation, closing the loop.

Therapeutically, the possibilities are still largely conceptual but tantalizing. Restoring Golgi structural integrity, for example through nonphosphorylatable GRASP55/65 variants, could in principle ameliorate multiple disease processes at once. More targeted options include nSMase2 inhibitors, which have already shown benefits in Alzheimer’s mouse models; overexpression of SORL1, which redirects the amyloid precursor protein to the Golgi and lowers amyloid-beta output; and reinforcement of glycosylation or lipid balance through COG7, glucosylceramide synthase, or OSBP1. The authors are candid about the caveats: causality between Golgi dysfunction and Alzheimer’s pathogenesis has not been rigorously established, most evidence comes from familial disease models rather than the sporadic form that accounts for roughly 90 percent of cases, and because the Golgi handles so much cellular traffic, interventions could carry pleiotropic side effects. Still, with anti-amyloid antibodies delivering only modest clinical benefit, the review makes a compelling case that keeping this cellular post office running smoothly may be one of the most underexplored strategies for halting the disease, and that the humble Golgi apparatus deserves a central seat at the Alzheimer’s research table.

Subject of Research: The role of Golgi apparatus dysfunction in Alzheimer's disease pathogenesis and therapy

Article Title: Golgi dysfunction in Alzheimer disease: from human multiomic signatures to therapeutic targets

Article References: Song, J., Lee, S.-J., & Mook-Jung, I. (2026). Golgi dysfunction in Alzheimer disease: from human multiomic signatures to therapeutic targets. Experimental & Molecular Medicine. https://doi.org/10.1038/s12276-026-01851-8

Image Credits: AI Generated

DOI: 10.1038/s12276-026-01851-8

Keywords: Alzheimer's disease, Golgi apparatus, amyloid-beta, tau, glycosylation, lipid metabolism, SORL1, trans-Golgi network, multiomics, neurodegeneration, endolysosomal trafficking, therapeutic targets

The central characters of the study belong to the UPF0016 family, an evolutionarily ancient group of membrane proteins found across fungi, plants, algae, and animals. In budding yeast, the family member Gdt1 works alongside the P-type ATPase Pmr1, a calcium and manganese pump, to maintain ion levels in the Golgi lumen. In humans, the corresponding protein TMEM165 is so essential that mutations in its gene cause congenital disorders of glycosylation, a group of serious developmental conditions. Yet S. pombe is unusual: unlike most species examined so far, it carries two UPF0016 paralogs, Gdt1 and Gdt2, whose physiological roles had remained essentially unexplored.

To dissect those roles, the researchers constructed single-gene deletion mutants lacking gdt1, gdt2, or pmr1, as well as all three possible double mutants, using one-step gene replacement with antibiotic resistance markers. They then subjected the strains to a battery of stress tests, spotting serial dilutions of cells onto agar plates laced with calcium chloride at 300, 400, and 750 millimolar, or manganese chloride at 0.8, 1.5, and 2 millimolar. The pattern that emerged was striking. Cells lacking gdt1 were markedly hypersensitive to both cations, while deletion of gdt2 or pmr1 alone produced only mild growth defects under the tested conditions.

The double mutants told a more dramatic story. Combining gdt1 and gdt2 deletions produced the most severe calcium-sensitive phenotype, with virtually no growth at 750 millimolar CaCl2, evidence that the two paralogs partially substitute for one another. The gdt1 pmr1 double mutant displayed strong synthetic sickness, its growth nearly undetectable at 400 millimolar calcium even though each single mutant survived with moderate defects. The gdt2 pmr1 combination was weaker but still明显 impaired, with residual growth persisting even at the highest dose. Together these genetic interactions indicate that Gdt1, Gdt2, and Pmr1 operate in complementary, overlapping pathways rather than as a single linear chain.

A chelation experiment confirmed the mechanism behind the toxicity. When the calcium-specific chelator EGTA was added to plates containing 400 millimolar CaCl2, growth of both the gdt1 mutant and the gdt2 pmr1 double mutant was substantially restored. This rescue demonstrates that the growth failures stem specifically from an inability to cope with excess free extracellular calcium, not from a general fitness defect. Manganese assays echoed the calcium results: the gdt1 gdt2 double mutant was nearly unable to grow at 2 millimolar MnCl2, while the gdt2 pmr1 strain grew reasonably well even at that concentration, showing that Gdt1 alone can sustain manganese tolerance across the range tested.

Growth curves in liquid culture reinforced the hierarchy. Wild-type cells reached an optical density of about 13.2 after 32 hours, whereas the gdt1 mutant plateaued at only 5.3, the lowest of the single mutants, followed by gdt2 at 7.4 and pmr1 at 8.5. Every double mutant fared worse than any single mutant, with the gdt1 pmr1 combination most severely affected at an optical density near 3.1. The data identify Gdt1 as the primary growth determinant among the three proteins and reinforce the conclusion that its function cannot be fully replaced by its paralog or by the ATPase.

Microscopy added a visible dimension to the genetics. Under standard conditions, healthy fission yeast cells are elongated rods, but all mutant strains were significantly shorter and rounder, averaging around 7.0 to 7.2 micrometers in length compared with 11.7 micrometers for wild type. Stress amplified these defects in distinctive ways: high calcium drove abnormal elongation, with the gdt1 pmr1 double mutant stretching to an average of 15.7 micrometers, while manganese produced the most extreme swelling, widening mutant cells to as much as 8.2 micrometers, nearly double the wild-type diameter. These distortions are consistent with compromised cell wall biosynthesis and disrupted glycosylation, processes known to depend on luminal calcium and manganese in the secretory pathway.

The study also delved into structure. Multiple sequence alignments across UPF0016 homologs from budding yeast, Candida albicans, Arabidopsis, Chlamydomonas, and humans showed that the two fission yeast proteins share 48.44 percent amino acid identity and both retain the family’s signature motifs, EIGDKT and EWGDRS, whose conserved glutamate and aspartate residues had previously been shown to be essential for calcium transport. Topology predictions, however, revealed a divergence: SpGdt1 is predicted to span the membrane five times, while SpGdt2 carries six transmembrane helices. In silico modeling with the MIB2 server mapped candidate metal-binding residues, identifying Glu38 and Glu190 as likely manganese coordinators in Gdt1, supported by Asp41 and Ser43 for the larger calcium ion, and Glu61 and Glu214 in the corresponding positions of Gdt2.

Phylogenetic analysis placed the fission yeast proteins on their own branch, separate from the single homolog of budding yeast, suggesting that the gdt1 and gdt2 pair arose from a lineage-specific gene duplication after the two yeast lineages split. Localization predictions using DeepLoc 2.0, together with curated PomBase and ORFeome annotations, assign SpGdt1 primarily to the endoplasmic reticulum and SpGdt2 to both the ER and Golgi, a compartmental pattern that differs from the Golgi residency of the budding yeast protein and may explain why the fission yeast pump Pmr1 itself localizes mainly to ER membranes in earlier fluorescence studies.

The implications reach well beyond a single yeast species. Because glycosylation enzymes require manganese and calcium cofactors, defects in UPF0016-dependent ion regulation can cascade into failures of protein maturation, secretion, and cell wall construction, which is precisely why human TMEM165 mutations manifest as congenital glycosylation disorders and why plant homologs such as PAM71 are indispensable for chloroplast manganese uptake and efficient photosynthesis. By establishing that Gdt1 is the dominant determinant of divalent cation tolerance in fission yeast while Gdt2 and Pmr1 provide complementary support, the study completes a missing evolutionary link and sets the stage for direct transport assays, motif-directed mutants, and organelle-level imaging to confirm how these conserved transporters move metal ions across secretory pathway membranes.

Subject of Research: Regulation of calcium and manganese ion homeostasis by UPF0016 family proteins Gdt1, Gdt2 and the P-type ATPase Pmr1 in the fission yeast Schizosaccharomyces pombe

Article Title: Gdt1, Gdt2 and the P-type ATPase Pmr1 regulate divalent cations (Ca²⁺ and Mn²⁺) in the fission yeast Schizosaccharomyces pombe

Article References: Ullah, F., & Huang, Y. (2026). Gdt1, Gdt2 and the P-type ATPase Pmr1 regulate divalent cations (Ca²⁺ and Mn²⁺) in the fission yeast Schizosaccharomyces pombe. International Microbiology. https://doi.org/10.1007/s10123-026-00887-0

Image Credits: AI Generated

DOI: 10.1007/s10123-026-00887-0

Keywords: Schizosaccharomyces pombe, UPF0016 family, Gdt1, Gdt2, Pmr1, calcium homeostasis, manganese transport, Golgi apparatus, endoplasmic reticulum, protein glycosylation, cell wall integrity, TMEM165