1. Introduction

The development and use of metformin – a longstanding cornerstone of type 2 diabetes mellitus (T2DM) therapy and a World Health Organisation essential medication – attest to the unpredictability of both scientific advancement and clinical translation. The quote from the legendary American baseball player and coach, Yogi Berra, well known for his malapropisms, is therefore apt. Originally derived from a plant (Galega officinalis) and used traditionally as a folk remedy, metformin’s substantial glucose-lowering capacity, without the induction of hypoglycaemia, was first appreciated in 1929. Despite this early recognition, metformin was not introduced for the management of T2DM until 1957 (in France) and only gained approval from the US Food and Drug Administration in 1995. It is now appreciated that metformin also has pleotropic properties beyond glucose lowering, which are being explored in diverse contexts, including ageing, cancer, and both cardiovascular and neurological disorders. Given its erratic development, it is perhaps not surprising that recent advances have redefined both the sites and mechanisms underlying the glucose-lowering action of metformin – a paradigm shift from the liver to the intestine [1]. This commentary summarises these insights and their substantial implications for refining the clinical application of metformin, particularly in settings where use of conventional formulations is constrained or contraindicated, such as gestational diabetes mellitus (GDM) and T2DM associated with renal impairment.

Objectives

The lateral hypothalamus (LH) plays a central role in appetite control, however the functional and evolutionary conservation of its subcircuits remain unclear. This study aimed to define the molecular and cellular identities of zebrafish LH neurons, identify conserved LH cell types across vertebrates, and investigate their roles in appetite regulation.

Methods

We performed the Act-seq method of single-cell RNA sequencing in the larval zebrafish LH under food-deprived and voracious feeding states to capture activity-dependent transcriptional signatures. Using integrative comparative transcriptomics, we aligned zebrafish neuronal clusters with a published mouse LH dataset to identify conserved neuronal sub-populations, and performed functional and molecular characterisation of a highly-conserved cell type in both zebrafish and mice.

Results

We identified several LH neuronal subtypes in zebrafish that are differentially activated during voracious feeding. Cross-species mapping revealed overlapping cellular clusters, especially for GABAergic neurons. We report a conserved GABAergic cluster co-expressing growth hormone (GH) receptors and tachykinin. In both species, feeding activates these neurons and elevates GH receptor and tachykinin expression. In zebrafish, upstream GH signaling is similarly regulated by feeding state, and acute GH administration both activates this cluster and enhances food intake.

Conclusions

These findings uncover a conserved GH receptor-tachykinin LH population which may link metabolic hormone signaling to appetite control. Beyond its established long-term roles in growth and metabolism, we propose that GH exerts acute appetite-enhancing effects through activation of this neuronal pathway. Our comparative LH atlas highlights the evolutionary biology of hypothalamic appetite circuits.

Objective

Mitochondria are involved in cellular metabolism, energy production, calcium homeostasis, and the synthesis of sterols and bile acids (BAs). Emerging evidence suggests that mitochondrial dynamics including biogenesis, fusion, fission, and mitophagy critically influence cardiometabolic diseases, yet their role in atherogenesis remain poorly understood. Mitochondrial fusion ensures metabolic flexibility and stress adaptation, processes highly relevant to lipid handling and vascular cell plasticity. OPA1, a key regulator of inner mitochondrial membrane fusion, has been implicated in metabolic remodeling and cellular stress responses. We therefore investigated whether modulation of OPA1 expression affects lipid homeostasis and plaque formation in LDL receptor-deficient (LDLR KO) mice and in human carotid atherosclerosis.

Methods

OPA1^TG/LDLR KO and OPA1^ΔHep/LDLR KO were fed with a Western-type diet (WTD) for 12 weeks. The development of atherosclerosis was compared to that of LDLR KO mice. In humans, the impact of OPA1 was investigated in asymptomatic and symptomatic subjects from the Carotid Plaque Imaging Project (CPIP) biobank.

Results

OPA1^TG/LDLR KO mice showed a significant increase in plasma cholesterol levels mainly in VLDL and LDL fractions. OPA1^TG/LDLR KO display a reduction of unconjugated bile acids and higher percentage of conjugated bile acids leading to an increased lipid adsorption. This phenotype was associated with increased atherosclerosis in the aortic root. OPA1 overexpression also resulted in an altered vascular smooth muscle cell (VSMC) cellular metabolism and differentiation, promoting a shift from a contractile/synthetic phenotype toward a more proliferative and metabolically active state. Concordantly, the deletion of OPA1 in hepatocytes improved systemic lipoprotein metabolism protecting from atherosclerosis. Concordantly in humans, plaque OPA1 mRNA levels are associated with metabolic and smooth muscle cell related pathways.

Conclusions

Mitochondrial fusion mediated by OPA1 plays a key role in atherosclerosis by affecting lipoprotein metabolism and vascular smooth muscle cell biology.

Objective

Metabolic inflexibility has been shown to be associated with type 2 diabetes (T2D) and diabetic nephropathy (DN). However, data are lacking, proving that reconstitution of metabolic flexibility by using a 6-month periodic fasting (PF) regimen may improve albuminuria.

Methods

In this post hoc analysis of a randomized-controlled trial, we investigated whether the PF regimen enhanced metabolic flexibility in individuals with T2D and DN showing improvement of albuminuria (responders) compared to non-responders. Participants followed every month either a 5-day fasting-mimicking diet or a Mediterranean diet for 6 months. LC-MS/MS-based comprehensive metabolic profiling was performed in plasma samples before, during, and after the intervention. Changes in metabolomic patterns and enriched signalling pathways were analysed between study groups.

Results

PF induced a sustained shift toward enhanced fatty acid oxidation, lipid utilization, and amino acids turnover, particularly in responders. Responders exhibited persistent elevations in short-chain acylcarnitines and cholesteryl esters, indicating more efficient lipid oxidation and tighter integration of lipid metabolism with the tricarboxylic acid cycle. Increased glycine and serine levels suggested enhanced cellular maintenance, a protein-sparing effect, and a metabolic shift favouring lipid over carbohydrate. In contrast, non-responders demonstrated only transient and limited metabolic shifts. Unsupervised clustering identified distinct metabolic response patterns, reinforcing the potential of personalized dietary interventions.

Conclusions

These findings demonstrate that diet-induced restoration of metabolic flexibility is associated with improved albuminuria in T2D, suggesting broader implications for precise nutritional strategies in diabetes management.

Objective

Chemical and mechanical signals from the gastrointestinal tract are critical for regulating satiety and glucose metabolism. While both nutrient sensing in the intestine and gastric distension has been well studied, the role of intestinal stretch in these metabolic processes remain unclear. This study evaluates the role of intestinal stretch in regulating food intake and glucose homeostasis in the context of normal body weight, obesity, and weight loss occurring via both dietary intervention and vertical sleeve gastrectomy (VSG).

Methods

We used the nonnutritive substance mannitol to selectively induce intestinal stretch in conscious mice. We assessed food intake, glucose tolerance, and neuronal activation in mice with normal body weight, obesity, or after dietary or surgically-induced weight loss. We employed chemogenetic approaches to inhibit GLP-1R and OxtR-expressing vagal afferents, and genetic and pharmacological strategies to ablate GLP-1 signaling to explore mechanisms for mannitol-induced suppression of feeding.

Results

Mannitol-induced intestinal stretch acutely suppressed food intake and improved oral glucose tolerance independent of GLP-1 signaling and vagal intestinal mechanosensation. Diet induced obesity impairs mannitol-induced intestinal stretch reductions in food intake and attenuates neuronal activation in the nucleus of the solitary tract (NTS) upon induction of intestinal stretch. Both dietary and surgical weight loss restored intestinal stretch-induced feeding suppression and enhanced NTS neuronal activation. Importantly, VSG heightened NTS neuronal activation in response to oral but not IP glucose.

Conclusions

Together, these data demonstrate that intestinal stretch contributes to the regulation of feeding and glucose metabolism independently of intestinal nutrient-sensing or classical gut hormones.

Objectives

The arcuate nucleus of the hypothalamus plays a pivotal role in metabolic homeostasis by integrating the functions of AgRP and POMC neurons. Dax1, a nuclear receptor-like transcription factor, is highly enriched in AgRP neurons; however, its role in energy balance regulation remains largely unexplored. Here, we demonstrate the function of Dax1 in hypothalamic AgRP neurons and its contribution to systemic energy homeostasis and thermogenesis in mice.

Methods

We generated AgRP neuron-specific Dax1 conditional knockout mice and assessed their physiological and metabolic responses under high-fat diet feeding and cold exposure. Energy expenditure, brown adipose tissue (BAT) thermogenesis, neuronal activation, and neuropeptide expression were evaluated. Molecular mechanisms were investigated by gene expression analysis, chromatin immunoprecipitation, and biochemical assays.

Results

We show that conditional deletion of Dax1 in AgRP neurons enhances energy expenditure, stimulates BAT thermogenesis, and confers resistance to diet-induced obesity in female mice. Notably, these mice exhibit blunted AgRP neuron activation upon cold challenge. Mechanistically, corticotropin-releasing factor receptor type 1 (CRFR1), a key regulator of AgRP neuronal excitability, was upregulated in Dax1-deficient AgRP neurons. We further identified that Dax1 recruits the HDAC3 corepressor complex to the glucocorticoid receptor at the glucocorticoid response element within the Crfr1 promoter, thereby repressing Crfr1 transcription in response to glucocorticoid signaling.

Conclusions

Our findings establish Dax1 as a critical transcriptional repressor of Crfr1 in AgRP neurons, linking hypothalamic steroid signaling to the regulation of adaptive thermogenesis and systemic energy balance.

Objectives

While glucagon-like peptide-1 (GLP-1) production has been previously documented in human alpha cells, the steps regulating its production and secretion are poorly characterized. We investigated the enzymes implicated in proglucagon processing, characterizing their expression and localization in primary human alpha cells and αTC1/9 cells.

Methods

Human alpha cells and αTC1/9 cells were maintained in control conditions or exposed to proinflammatory and Akt-activating stimuli to enhance GLP-1 levels. Proglucagon and convertase enzyme gene expression, protein content, and subcellular localization were evaluated by qPCR, Western Blot, and immunofluorescent microscopy, respectively.

Results

Our data suggests that the canonical GLP-1-producing enzyme, Prohormone Convertase 1/3 (PC1/3), is poorly expressed and localized in alpha cells, while its homologue furin is optimally positioned for GLP-1 production. We also note that GLP-1 and glucagon processing occur in different subcellular compartments, creating two distinct pools of secretory granules which respond to similar secretory stimuli.

Conclusion

Our study suggests that furin, rather than PC1/3, is positioned to process proglucagon into GLP-1, and despite coming from the same precursor molecule, GLP-1 and glucagon are separately packaged in primary human alpha cells.

Objectives

Although the mechanism of action of the antidiabetic drug metformin is still a matter of discussions, increasing evidence points to a pivotal role of the gut. Aiming to clarify whether metformin-induced changes in the intestinal tract directly contribute to metabolic improvement, we evaluated the effects of escalating doses (from 50 to 200 mg/kg/day) of metformin orally administered for 4 weeks in mice made glucose intolerant by ten weeks of high fat high sucrose diet.

Methods

Several intestinal parameters were studied, including caecal microbiota composition and bile acids profile, ileal FXR signaling, abundance of GLP1-producing cells and goblet cells and blood metabolome.

Results

Metformin restored glucose tolerance, fasting insulinemia and HOMA-IR index in a dose-dependent manner. Only a subset of gut-related effects, including mucus production and GLP-1 expression, exhibited a parallel dose–response relationship, suggesting a possible contribution to the observed metabolic improvements. In contrast, other changes, including ileal Fxr-Fgf15 inhibition and hepatic ceramide reduction did not scale with dose, suggesting they are not the main drivers of metformin dose-dependent effects on glycemic control. We also pointed out marked differential sensitivity of gut bacteria to metformin supporting complex interactions of the drug with the microbial ecosystem.

Conclusion

Finally, metformin enhanced the proliferation of intestinal epithelium, resulting in increased length of ileal villi. Altogether, this study offers new insights into the metformin mechanism of action and revealed potential novel microbial biomarkers and targets for enhancing its therapeutic efficacy.

Background and aims

Adipose tissue (AT) senescence, induced by obesity or aging, leads to a reduced capacity for tissue remodeling and a chronic pro-inflammatory state, which leads to the onset of metabolic pathologies. Cellular senescence is triggered by various stresses, in particular excessive shortening of telomeres, which activates the p21 pathway and leads to the arrest of the cell cycle. We used the mouse model p21^+/Tert expressing TERT from the Cdkn1a locus to investigate whether counteracting telomere shortening by telomerase (TERT) specifically in pre-senescent cells could improve obesity-induced metabolic disorders.

Results

Our study demonstrates that conditional expression of TERT reduces insulin-resistance and glucose intolerance associated with obesity. In AT, this is accompanied by a decrease in the number of senescent p21-positive cells, very short telomeres, and oxidative DNA damage. Single nucleus RNA-seq data reveal TERT expression attenuates senescence induced by HFD in particular in adipose stem and progenitor cells (ASPC). We demonstrate that ASPC expansion and differentiation are promoted in p21^+/Tert obese mice, thereby improving AT plasticity. Furthermore, we show that TERT expression enhances mitochondrial function and alleviates oxidative stress in ASPC. This process contributes to the AT hyperplasia with increased number of adipocytes which has been shown to have a protective effect against obesity-associated metabolic disorders.

Conclusions

These results underscore TERT's role in mitigating obesity-related metabolic dysfunction. Conditional TERT expression may therefore represent as a promising therapeutic strategy for obesity-associated metabolic disorders.

Background

Extracellular vesicles (EVs), conveyors of microRNAs, have recently been linked to obesity. As taste is a potent driver of eating behaviour and food intake, it's connection to EVs is of increasing interest. This study aimed at deciphering the salivary EV-microRNA profile in relation to taste perception and metabolic pathways of obesity.

Methods

Small RNA sequencing was performed on isolated salivary EVs of 90 participants from the Obese-Taste-Bud study. Pathway enrichment and association analyses were conducted to link identified microRNAs to taste recognition, eating behaviour, food intake and various anthropometric-, metabolic- and oral health parameter.

Results

The 626 identified microRNAs clustered into pathways related to energy regulation, obesity and diabetes, cell signaling and taste perception. The top three enriched microRNAs are miR-1246, miR-1290 and miR-148a-3p which showed significant associations with fasting blood glucose and cholesterol level, anthropometrics and blood pressure (p < 0.05). Additionally, these microRNAs associate with trait eating behaviour (p < 0.05). Several other microRNAs were linked to differences in taste recognition scores and are further related to parameters of glucose metabolism and periodontal health, salivary insulin level or food intake (p < 0.05).

Conclusions

This study, one of the largest on salivary EVs, supports an interrelation of EV's microRNA load with metabolism, eating behaviour and taste recognition offering potential targets for obesity intervention.

Obesity is the principal driver of insulin resistance, and lipodystrophy is also linked with insulin resistance, emphasizing the vital role of adipose tissue in glucose homeostasis. The quality of adipose tissue expansion is a critical determinant of insulin resistance predisposition, with individuals suffering from metabolic unhealthy adipose expansion exhibiting greater risk. Adipocytes are pivotal in orchestrating metabolic adjustments in response to nutrient intake and cell intrinsic factors that positively regulate these adjustments are key to prevent Type-2 diabetes. Employing unique genetic mouse models, we established the critical involvement of heparan sulfate (HS), a fundamental element of the adipocyte glycocalyx, in upholding glucose homeostasis during dietary stress. Genetic models that compromise adipocyte HS accelerate the development of high-fat diet-induced hyperglycemia and insulin resistance, independent of weight gain. Mechanistically, we show that perturbations in adipocyte HS disrupts endogenous FGF1 signaling, a key nutrient-sensitive effector. Furthermore, compromising adipocyte HS composition detrimentally impacts FGF1-FGFR1-mediated endocrinization, with no significant improvement observed in glucose homeostasis. Our data establish adipocyte HS composition as a determinant of Type 2 diabetes susceptibility and the critical dependency of the endogenous adipocyte FGF1 metabolic pathway on HS.

Objectives

Acetyl-CoA carboxylase enzymes ACC1 and ACC2 promote liver fat storage. Accordingly, ACC inhibition represents a strategy to reverse fatty liver disease and related disorders. Human and rodent studies show that targeting both ACC isotypes can reverse some fatty liver phenotypes, but also result in unwanted metabolic phenotypes including hypertriglyceridemia. The objective of this study was to determine whether liver-selective genetic inhibition of ACC1 or ACC2 individually can reverse fatty liver disease phenotypes without adverse metabolic phenotypes in a mouse model of fatty liver disease.

Methods

Four genotypes of male C57BL/6J mice floxed for ACC1, ACC2, both ACC alleles, or no ACC alleles were fed an Amylin diet for 28 weeks to induce fatty liver disease. After 20 weeks of Amylin feeding, ACC genes were deleted in the liver by adeno-associated virus 8 (AAV8)-mediated Cre recombinase expression. Mice were metabolically phenotyped and liver disease was assessed by histopathology.

Results

Dual inhibition of ACC enzymes was necessary to achieve significant reversal of fatty liver disease and fibrosis; however, it also caused hypertriglyceridemia, weight gain, and glucose intolerance. ACC1 inhibition alone resulted in partial reversal of fatty liver disease phenotypes but drove all undesired metabolic phenotypes. In contrast, ACC2 inhibition alone had minimal effect on fatty liver, fibrosis, or metabolic phenotypes.

Conclusions

Our results indicate that complete inhibition of liver ACC activity is required to resolve fatty liver disease and fibrosis, with ACC1 inhibition being the dominant driver of unwanted metabolic dysregulation. Accordingly, selective inhibition of ACC2 with partial inhibition of ACC1 may represent a refined future approach to reverse fatty liver disease phenotypes while minimizing metabolic dysregulation.

Objectives

Obesity is linked to metabolic disorders including type 2 diabetes, metabolic dysfunction-associated steatotic liver disease, and cardiovascular disease. Lifestyle interventions, such as time-restricted feeding (TRF), have proven to be effective for long-term weight management. The metabolic effects of TRF are closely associated with circadian clock function in the liver. We previously demonstrated that the circadian gene Period 1 (Per1) mediates responses to acute fasting in both sexes. We therefore hypothesized that hepatocyte Per1 contributes to the long-term adaptations to repeated fasting exposure in the form of TRF, and investigated its role in diet-induced obesity in both sexes.

Methods

Male and female mice with or without hepatocyte Per1 (Per1^fl/fl and Per1^LKO) were subjected to either ad libitum feeding (ALF) or TRF restricted to the active phase (8 h/day).

Results

TRF attenuated Western diet-induced weight gain and peripheral and hepatic lipid accumulation, and improved heat production, metabolic substrate flexibility, and glucose homeostasis in Per1^fl/fl and Per1^LKO males. In contrast, hepatocyte Per1 was required for TRF-induced improvements in energy expenditure and peripheral and hepatic lipid accumulation in females. Surprisingly, TRF failed to significantly attenuate diet-induced weight gain or glucose and insulin tolerance in females independent of genotype. Transcriptomic data revealed sex-specific transcriptional responses to TRF and to hepatocyte-specific Per1 deletion. Specifically, genes involved in lipid metabolism were differentially regulated when comparing TRF-treated Per1^fl/fl and Per1^LKO female mice.

Conclusions

Hepatocyte Per1 mediates the energy, lipid, and glucose homeostatic effects of TRF, and this regulation is almost completely sex-dependent.

Objectives

Gamma-aminobutyric acid (GABA) is produced in pancreatic beta cells and is implicated in modulating islet function, yet its precise physiological role remains uncertain. This study aimed to determine the function of endogenous beta cell-derived GABA on insulin secretion and islet calcium dynamics by developing a conditional beta cell-specific knockout of GABA-synthesizing enzymes (GAD65 and GAD67).

Methods

Conditional knockout mice (Gad ^βKO) lacking both GAD65 and GAD67 specifically in pancreatic beta cells were generated. Glucose-stimulated insulin secretion was measured in isolated islets and in vivo and islet Ca²⁺ oscillations were recorded using calcium imaging. The effects of GABA and its receptor agonists/antagonists were tested under various glucose conditions. Additional analyses were performed in high-fat diet-fed mice and human islets from donors with and without type 2 diabetes (T2D).

Results

Gad ^βKO islets were devoid of GABA and showed excessive insulin secretion in response to glucose without anatomical changes in islet composition. These islets had defective Ca²⁺ oscillations, with prolonged active phases and reduced amplitudes. GABA application suppressed Ca²⁺ oscillations, an effect mediated by GABA_A and GABA_B receptors. High-fat diet-fed and T2D human islets were unresponsive to GABA and exhibited impaired Ca²⁺ oscillations.

Conclusions

This is the first study using a beta cell-specific GAD65/GAD67 knockout model. Endogenous beta cell-derived GABA is critical for modulating insulin secretion by maintaining proper Ca²⁺ oscillation dynamics. GABA signaling likely operates as a delayed negative feedback mechanism that reinforces oscillatory homeostasis in islets. The loss of GABA responsiveness, as seen in metabolic stress or T2D, may contribute to islet dysfunction. This work establishes GABA as a key regulator of islet rhythm and glucose responsiveness.

Objectives

Eloralintide (LY3841136), a novel amylin analog, was evaluated in translational studies to characterize its therapeutic potential for treating obesity.

Methods

In vitro assays were performed in cell lines selectively expressing rat or human amylin 1 receptor (AMY1R), amylin 3 receptor (AMY3R), or calcitonin receptor (CTR). In vivo studies were conducted in rats and monkeys. A phase 1, randomized, placebo-controlled, participant/investigator-blinded trial evaluated the safety and tolerability of single-ascending eloralintide doses (0.04–12 mg) in healthy participants (NCT05295940).

Results

In vitro, eloralintide preferentially activated human AMY1R (12-fold > CTR, 11-fold > AMY3R), while in rats, both AMY1R and AMY3R were activated more potently than CTR. Eloralintide induced significantly less conditioned taste avoidance in lean rats than cagrilintide, a non-selective amylin receptor agonist (p < 0.05). Eloralintide dose dependently reduced food intake and lowered body weight, primarily through fat mass loss, in diet-induced obese rats. Eloralintide demonstrated favorable pharmacokinetics in both rats and monkeys. In the phase 1 trial, 48 healthy participants had a mean body mass index of 27.5 kg/m². Nine participants in the eloralintide cohorts reported 16 adverse events, with most being mild (n = 15/16). Two participants reported 4 gastrointestinal events, including one moderate vomiting event. The pharmacokinetic profile of eloralintide supports once-weekly dosing. In eloralintide cohorts receiving single doses of 4 or 12 mg, week-4 mean percent change from baseline in body weight was −2.5% (p < 0.01) and −4.4% (p < 0.001), respectively, vs placebo (+0.6%).

Conclusions

Once-weekly dosing with eloralintide, an AMY1R-selective agonist, may offer a promising new therapeutic with favorable gastrointestinal tolerability for the treatment of obesity.

Background/Purpose

Obesity-associated metabolic disorders, including type 2 diabetes and metabolic dysfunction associated fatty liver disease (MAFLD), are major global health burdens. While dietary polyphenols have shown promise in ameliorating these conditions, their efficacy is dependent on specialized gut microbial metabolism, and the underlying molecular mechanisms remain mostly elusive. Here, we demonstrate that dietary supplementation with polyphenol-rich elderberry (Eld) extract abrogates the effects of an obesogenic diet in a gut microbiota-dependent manner, preventing insulin resistance and reducing hepatic steatosis in mice.

Methods

We developed a targeted, quantitative liquid chromatography-tandem mass spectrometry method for detection of gut bacterial polyphenol catabolites and identified 3-phenylpropionic acid as a key microbial metabolite in the portal plasma of Eld supplemented animals.

Results

We showed that 3-phenylpropionic acid potently activates hepatic AMP-activated protein kinase α, explaining its role in improved liver lipid homeostasis. We further uncovered the metabolic pathway cumulating in 3-phenylpropionic acid for the common gut commensal Clostridium sporogenes.

Conclusion

Our findings establish 3-phenylpropionic acid as a diet-derived, microbiota-dependent metabolite with insulin-sensitizing and anti-steatotic activities and provide a molecular basis for prebiotic interventions to improve host metabolic health.

T-cell acute lymphoblastic leukaemia (T-ALL) is a haematological malignancy commonly driven by NOTCH1 activating mutations. A concomitant feature associated with NOTCH1 mutations is heightened oxidative metabolism enabling the exponential proliferation of T-ALL blasts. As such, targeting mitochondrial metabolism in T-ALL is an attractive therapeutic avenue. Related to this, canagliflozin (cana), is an FDA-approved sodium glucose co-transporter 2 inhibitor with known off-target effects on complex I and glutamate dehydrogenase, but its potential anti-leukaemic effects remain unexplored. Here, we show that cana possesses potent anti-leukaemic effects underpinned by proliferative defects, cell cycle disruption and apoptosis. These anti-leukaemic effects driven by cana, are attributed to a perturbed tricarboxylic acid (TCA) cycle and mitochondrial metabolism, and elevated mitochondrial ROS. Proteomic analysis revealed that cana treatment resulted in a compensatory increase in the expression of ATF4 targets, including upregulation of serine biosynthesis pathway and one-carbon metabolism enzymes. As such, restriction of serine and glycine synergized with cana treatment, further enhancing its anti-leukaemic effects. Collectively, our study reveals a cana-driven metabolic vulnerability that can be further exploited via dietary manipulation to treat T-ALL.

Purpose

Blocking the Activin receptor type IIA and IIB (ActRIIA/IIB) has clinical potential to increase muscle mass and improve glycemic control in obesity, cancer, and aging. However, the impact of blocking ActRIIA/IIB on strength, metabolic regulation, and insulin action remains unclear.

Methods

Here, we investigated the effect of short- (10 mg kg⁻¹ bw, once, 40h) or long-term (10 mg kg⁻¹ bw, twice weekly, 21 days) antibody treatment targeting ActRIIA/IIB (αActRIIA/IIB) in lean and diet-induced obese mice and engineered human muscle tissue.

Results

Short-term  ActRIIA/IIB administration in lean mice increased insulin-stimulated glucose uptake in skeletal muscle by 76–105%. Despite this, ActRIIA/IIB-treated mice exhibited 33% elevated blood glucose and glucose intolerance. Long-term αActRIIA/IIB treatment increased muscle mass (+20%) and reduced fat mass (−8%) in obese mice but failed to enhance insulin-stimulated glucose uptake in muscle or adipose tissue. Instead, it induced glucose intolerance, cardiac hypertrophy with glycogen accumulation, and elevated hepatic triacylglycerol and glucose output in response to pyruvate. Concomitantly, long-term ActRIIA/IIB treatment increased strength (+30%) in mouse soleus muscle and prevented activin A-induced loss of tissue strength in engineered human muscle tissue. Surprisingly, long-term  ActRIIA/IIB treatment lowered volitional running (−250%).

Conclusions

Our findings demonstrate that, in accordance with human studies, ActRIIA/IIB blockade holds promise for increasing muscle mass, strength, and muscle insulin sensitivity. However, contrary to the improved glycemic control in humans, ActRIIA/IIB blockade in mice causes severe glucose intolerance and lowers voluntary physical activity. Our study underscores the complex metabolic and functional consequences of ActRIIA/IIB blockade, and highlight species differences on glycemic control, which warrant further investigation.