The research, led by Melissa Bowerman of Keele University’s School of Medicine together with colleagues at the University of Hertfordshire and the Wolfson Centre for Inherited Neuromuscular Disease, builds on earlier work from the same laboratory that combined bioinformatics with drug repositioning strategies to identify compounds capable of correcting metabolic defects in SMA. Rather than starting from scratch with novel molecules, the team deliberately focused on drugs that are already approved for human use, an approach that could shorten the path from bench to bedside considerably. The three candidates that emerged—pioglitazone, a thiazolidinedione used to treat type 2 diabetes; melatonin, a hormone that regulates circadian rhythms; and insulin, the classic metabolic hormone—each target a different facet of cellular energy handling.

The experimental system at the heart of the study is the Smn2B/- mouse, a well-established model of SMA that carries a deletion of the mouse Smn gene alongside a human SMN2 transgene. This model recapitulates many features of the human disease, including motor dysfunction, muscle atrophy, shortened lifespan and systemic metabolic abnormalities. The researchers treated these mice with each of the three compounds and assessed a battery of behavioural, molecular and histological endpoints. Alongside the mouse work, they used the nematode worm Caenorhabditis elegans as a complementary in vivo platform, allowing rapid evaluation of the compounds’ effects in a second organism with conserved metabolic pathways.

The results, the team reports, were encouraging across the board, albeit to different degrees for each compound. All three drugs improved various pathological features in the SMA mice and worms, including survival, body weight, motor function, muscle size, the health of the spinal cord and the accumulation of lipids in the liver. Hepatic steatosis—the abnormal build-up of fat in liver tissue—is one of the metabolic pathologies increasingly recognised in SMA patients and models, and its improvement following treatment suggests that the compounds were acting on genuine disease-relevant biology rather than producing non-specific effects. Improvements in muscle size and spinal cord health point to benefits that extend beyond the liver into tissues central to neuromuscular function.

Of the three interventions, melatonin produced the most significant effect on survival, the endpoint that carries the greatest weight in preclinical SMA research. This finding is particularly striking because melatonin is not typically thought of as a metabolic drug; its best-known role is as a circadian signal produced by the pineal gland. Yet the study found that melatonin’s activity in SMA mice extended across several tissues, influencing molecular effectors involved in circadian rhythm regulation, glucose metabolism, mitochondrial biogenesis and the browning of white adipose tissue. Browning—the conversion of energy-storing white fat into energy-burning beige or brown fat—is a process with profound implications for systemic energy balance, and its disruption has been implicated in the metabolic dysfunction seen in SMA.

The involvement of mitochondria is another thread worth unpacking. Mitochondria are the power plants of the cell, and their biogenesis—the generation of new mitochondrial material—is governed by molecular pathways that respond to metabolic stress. In SMA, mitochondrial defects have been observed in multiple tissues, and the ability of melatonin to influence mitochondrial biogenesis suggests a mechanism by which the hormone could restore cellular energy capacity in vulnerable tissues such as muscle and liver. Similarly, its effects on glucose metabolism echo the insulin resistance and dyslipidaemia documented in SMA patients, abnormalities that current disease-modifying therapies do not adequately address.

That last point is crucial to understanding why the study matters. The last several years have seen a remarkable transformation in SMA care, with the arrival of nusinersen, an antisense oligonucleotide that modifies SMN2 splicing; onasemnogene abeparvovec, a gene therapy that delivers a functional copy of the SMN1 gene; and risdiplam, an oral SMN2 splicing modifier. These therapies have delivered dramatic gains in survival and motor function, particularly when treatment begins early. Yet they share a common limitation: they are designed to raise SMN levels, primarily benefiting the neuromuscular system, and they leave the peripheral and metabolic pathologies of the disease largely untouched. Patients treated with these drugs still exhibit metabolic abnormalities, and the peripheral tissues—skeletal muscle, liver, pancreas and adipose tissue—remain sites of ongoing dysfunction. The new study argues that this therapeutic gap is precisely where metabolism-targeted interventions could make a difference.

The concept of SMA as a metabolic disease is grounded in the biology of SMN itself. Although the protein is best known for its role in the assembly of spliceosomal ribonucleoproteins, its loss produces detectable abnormalities in tissues far removed from the motor neuron. Insulin resistance, hepatic steatosis, dyslipidaemia and circadian disruption have all been documented in SMA, and these abnormalities are not merely consequences of immobility; they appear to arise from cell-autonomous metabolic defects. Reframing SMA pathology from a neurocentric to a metabolic perspective, as the authors put it, reveals a disease landscape in which energy handling goes wrong in parallel with, and possibly contributes to, neuromuscular degeneration. On this view, correcting metabolic dysfunction is not an afterthought but a legitimate therapeutic goal in its own right.

The translational appeal of the approach lies in the fact that all three compounds are already commercially approved. Pioglitazone is prescribed worldwide for type 2 diabetes and has a well-characterised safety profile, although its use is associated with weight gain and, in some patients, concerns about fluid retention and fracture risk. Melatonin is available over the counter in many countries and is generally well tolerated. Insulin, of course, is a mainstay of diabetes management, though its use in non-diabetic patients would require careful dosing and monitoring. The authors are careful to note that the study was conducted in mouse and worm models, and that the doses, timing and combinations used in animals may not translate directly to humans. Clinical trials would be needed to establish whether these interventions, alone or in combination with existing SMN-restoring therapies, can deliver measurable benefits in patients. Nevertheless, the fact that the compounds are approved means that safety data already exist, potentially accelerating the design of early-phase studies.

The broader significance of the work may lie in the shift it represents in how the field thinks about combination therapy for SMA. Just as oncology moved from single-agent treatments to rational multi-drug regimens that attack different vulnerabilities simultaneously, neuromuscular medicine may be heading toward pairing SMN-restoring therapies with second-generation treatments aimed at specific non-neurological pathologies. The findings position metabolism, as the authors conclude, at the forefront of targets for SMA treatments and provide a strong rationale for exploring metabolism-targeted second-generation therapies to complement currently approved disease-modifying treatments. For a disease that was once considered untreatable, and which now has effective but incomplete therapies, the prospect of adding metabolic correction to the therapeutic arsenal represents a meaningful step forward—one that could matter most for the patients whose peripheral symptoms persist despite the most advanced neuromuscular interventions available today.

Subject of Research: Testing commercially approved metabolism-targeting drugs in a mouse model of spinal muscular atrophy

Article Title: Treating Smn2B/− spinal muscular atrophy (SMA) mice with commercially approved metabolism-targeting interventions leads to improved disease phenotypes

Article References: Çetin, Ö., McCallion, E., Hoolachan, J. M., Sutton, E. R., Cook, J., Al-Mozani, Y., Dhoowooah, A., Varughese, M. S., Velandia Dorta, L. F., Koomson, J., Rashid, S., Pacheco-Torres, P., Dimitriadi, M., & Bowerman, M. (2026). Treating Smn2B/− spinal muscular atrophy (SMA) mice with commercially approved metabolism-targeting interventions leads to improved disease phenotypes. Cellular and Molecular Life Sciences. https://doi.org/10.1007/s00018-026-06461-1

Image Credits: AI Generated

DOI: 10.1007/s00018-026-06461-1

Keywords: spinal muscular atrophy, metabolism, melatonin, pioglitazone, insulin, Smn2B/- mice, drug repositioning, mitochondrial biogenesis, hepatic steatosis, circadian rhythm, adipose tissue browning, combination therapy

The research team, led by Shuning Liu and Chang Liu of Beijing Sport University together with collaborators from Lanzhou University, Wuhan Sports University and other institutions, set out to determine whether syringaresinol could activate a well-known signaling circuit that connects muscle and fat tissue. This circuit runs through SIRT1, a NAD-dependent deacetylase enzyme long associated with calorie restriction and mitochondrial health, which in turn activates PGC-1α, the master regulator of mitochondrial biogenesis. PGC-1α then promotes expression of FNDC5, the membrane protein whose cleaved extracellular fragment is the hormone irisin. Irisin released into the bloodstream acts on adipose tissue, encouraging white fat cells to adopt brown-fat-like characteristics—producing heat, burning calories, and reshaping systemic energy balance.

In the laboratory phase of the study, the team used differentiated C2C12 myotubes, the standard cell model for mature skeletal muscle, and treated them with syringaresinol alongside two chemical reference compounds: SRT1720, a potent SIRT1 activator, and EX-527, a selective SIRT1 inhibitor. The results were striking. Myotubes exposed to syringaresinol showed increased irisin-related readouts, elevated ATP content, and higher citrate synthase activity, a classic indicator of enhanced mitochondrial oxidative capacity. At the molecular level, the compound produced transcriptional changes consistent with SIRT1/PGC-1α/FNDC5 activation and increased the abundance of both SIRT1 and PGC-1α proteins, placing syringaresinol squarely in the same mechanistic territory as established metabolic interventions.

The critical question was whether these effects genuinely depended on SIRT1. The inhibitor experiments provided the answer: when EX-527 blocked SIRT1 activity, the syringaresinol-driven responses in the myotubes were substantially attenuated. This pharmacological loss-of-function evidence supports the conclusion that SIRT1 signaling sits upstream of the observed changes and is required for syringaresinol to exert its influence on irisin production and mitochondrial markers in muscle cells. It is a level of mechanistic rigor that many plant-compound studies lack, and it gives the findings considerably more weight than simple correlation would allow.

But cell culture only goes so far, and the team therefore moved to a living system. Mice fed a high-fat diet—the standard model of diet-induced obesity—received syringaresinol by oral gavage at either a low or a high dose for 18 weeks, a substantial intervention period that allowed metabolic adaptations to fully develop. Over those weeks, the treated animals gained significantly less body weight than their untreated high-fat-diet counterparts. Crucially, food intake did not differ significantly between groups, which means the anti-obesity effect could not be explained by reduced appetite or caloric restriction. Something else was happening to the animals’ energy economy.

That something else appears to be a combination of circulating irisin and fat-tissue remodeling. Plasma measurements revealed that syringaresinol-treated mice had elevated levels of circulating irisin, consistent with the muscle-cell findings. The compound also improved lipid profiles, lowering the LDL-C/HDL-C ratio—a marker of cardiometabolic risk. In inguinal white adipose tissue, the subcutaneous fat depot most amenable to browning, expression of PGC-1α, uncoupling protein 1 (Ucp1), and Pparγ all increased. Ucp1 is the molecular signature of thermogenically active brown and beige fat: it short-circuits the mitochondrial proton gradient to generate heat instead of ATP, effectively burning calories as warmth. Its upregulation in white fat depots is the hallmark of the browning process that irisin was originally discovered to induce.

The original discovery of irisin in 2012 by Bruce Spiegelman’s group demonstrated that a PGC-1α-dependent myokine released from exercising muscle could drive brown-fat-like development in white fat and stimulate thermogenesis, and the field has since been searching for safe, practical ways to amplify this axis in people who cannot simply exercise their way out of metabolic disease. Recombinant irisin has been shown to induce weight loss in obese mice by increasing energy consumption and thermogenesis, and irisin has been linked to improved fatty acid oxidation and glucose utilization through AMPK signaling. Syringaresinol now emerges as a candidate nutritional tool for tapping into that same axis, working through the upstream SIRT1 node that is also targeted by compounds such as resveratrol and, more recently, by other dietary polyphenols like sesamol.

Syringaresinol itself is no newcomer to scientific attention. Prior studies have reported that it modulates gut microbiota and delays immunosenescence in middle-aged mice, protects against type 1 diabetic cardiomyopathy by reducing inflammation and oxidative stress, attenuates osteoarthritis through the NF-κB pathway, and even shows promise in models of cognitive decline and Alzheimer’s-related pathology. Toxicological testing of syringaresinol and its enterolignan metabolites has been carried out, and a comprehensive 2025 review has catalogued its plant sources, pharmacological activities, and pharmacokinetic characteristics. The new study adds weight management and the muscle–adipose endocrine axis to this expanding portfolio, positioning the compound as a multi-target nutritional agent rather than a single-action drug.

The researchers are appropriately careful about the limits of their evidence. In the published paper, they note that while the findings support syringaresinol as a candidate nutritional modulator of muscle–adipose metabolic communication, causal mediation of the in vivo effects by SIRT1, FNDC5, or irisin requires further pathway-specific validation. In other words, the mouse study shows correlations—less weight gain, more irisin, more Ucp1—but does not yet prove, through knockout models or receptor blockade, that irisin is the indispensable messenger carrying the benefit from muscle to fat. Human trials, which would represent the ultimate test, remain on the horizon. Still, the convergence of in vitro pharmacology, live-animal outcomes, and a mechanistic framework anchored in one of the most extensively studied metabolic pathways gives the work unusual coherence.

For a field wrestling with rising obesity rates and the modest long-term success of lifestyle interventions alone, the appeal of a plant-derived molecule that amplifies an exercise-like hormonal signal is obvious. Syringaresinol is found in common plant foods, has a documented safety profile, and now demonstrates the ability to switch on the SIRT1–PGC-1α–FNDC5/irisin axis in both cells and living animals under obesogenic conditions. If future work confirms causality and translates to humans, the compound—or optimized derivatives of it—could become part of a nutritional strategy that works with the body’s own thermogenic machinery rather than against appetite. For now, the message is more measured but still compelling: a molecule hidden in plants may teach muscle to talk to fat in a language that favors staying lean.

Subject of Research: Activation of the skeletal muscle SIRT1–FNDC5/irisin axis by the plant lignan syringaresinol and its effects on diet-induced obesity

Article Title: Syringaresinol activates the skeletal muscle SIRT1–FNDC5/irisin axis to enhance weight management

Article References: Syringaresinol activates the skeletal muscle SIRT1–FNDC5/irisin axis to enhance weight management. (n.d.). https://doi.org/10.1007/s13205-026-05027-z

Image Credits: AI Generated

DOI: 10.1007/s13205-026-05027-z

Keywords: syringaresinol, irisin, SIRT1, PGC-1α, FNDC5, skeletal muscle, adipose tissue browning, obesity, mitochondrial biogenesis, high-fat diet, lignan, weight management