Pub Date : 2026-01-01DOI: 10.1016/j.molmet.2025.102315
Tobias Hagemann , Anne Hoffmann , Kerstin Rohde-Zimmermann , Helen Broghammer , Lucas Massier , Peter Kovacs , Michael Stumvoll , Matthias Blüher , John T. Heiker , Juliane Weiner
Background
Controlling brown adipose tissue (BAT) plasticity offers potential for novel obesity therapies. DNA methylation is closely linked to thermogenic and metabolic pathways and thereby influences BAT function. How metabolic state and cold exposure interact to shape methylation-dependent BAT gene regulation was investigated.
Methods
Five-week-old mice were fed either chow for 11 weeks (lean) or high-fat diet for 22 weeks to induce obesity (DIO), after which cold exposure was applied for seven days. BAT transcriptomes (RNAseq) and methylomes (RRBS) were generated, and differentially methylated and expressed genes (DMEGs) showing metabolic state–dependent cold responses were identified. Pathway enrichment, epigenetic regulator screening, and transcription factor (TF) motif analyses were performed. DNA methylation was experimentally modulated in vitro to validate selected gene expression responses.
Results
A total of 1,364 differentially expressed genes (DEGs) were uniquely affected by the interaction of metabolic state and cold, with most downregulated in DIO mice. Sixty-five DMEGs (4 % of DEGs) showed metabolic state–specific responses to cold. In DIO mice, DMEGs were enriched in pathways associated with mitochondrial dysfunction, altered lipid metabolism, neuroendocrine signaling, and stress responses. Several epigenetic regulators, including Tet2, Dnmt3a, and Apobec1, exhibited metabolic state- and cold-dependent expression, and TF-motif analyses highlighted roles for AhrArnt and Foxn1. In vitro assays confirmed that DNA methylation influences expression of thermogenic genes.
Conclusion
These findings provide the first evidence that the epigenetic cold response of BAT differs by metabolic condition. BAT remodeling is shaped by coordinated transcriptional and epigenetic mechanisms integrating environmental and metabolic cues.
{"title":"Diet and temperature interactively impact brown adipose tissue gene regulation controlled by DNA methylation","authors":"Tobias Hagemann , Anne Hoffmann , Kerstin Rohde-Zimmermann , Helen Broghammer , Lucas Massier , Peter Kovacs , Michael Stumvoll , Matthias Blüher , John T. Heiker , Juliane Weiner","doi":"10.1016/j.molmet.2025.102315","DOIUrl":"10.1016/j.molmet.2025.102315","url":null,"abstract":"<div><h3>Background</h3><div>Controlling brown adipose tissue (BAT) plasticity offers potential for novel obesity therapies. DNA methylation is closely linked to thermogenic and metabolic pathways and thereby influences BAT function. How metabolic state and cold exposure interact to shape methylation-dependent BAT gene regulation was investigated.</div></div><div><h3>Methods</h3><div>Five-week-old mice were fed either chow for 11 weeks (lean) or high-fat diet for 22 weeks to induce obesity (DIO), after which cold exposure was applied for seven days. BAT transcriptomes (RNAseq) and methylomes (RRBS) were generated, and differentially methylated and expressed genes (DMEGs) showing metabolic state–dependent cold responses were identified. Pathway enrichment, epigenetic regulator screening, and transcription factor (TF) motif analyses were performed. DNA methylation was experimentally modulated <em>in vitro</em> to validate selected gene expression responses.</div></div><div><h3>Results</h3><div>A total of 1,364 differentially expressed genes (DEGs) were uniquely affected by the interaction of metabolic state and cold, with most downregulated in DIO mice. Sixty-five DMEGs (4 % of DEGs) showed metabolic state–specific responses to cold. In DIO mice, DMEGs were enriched in pathways associated with mitochondrial dysfunction, altered lipid metabolism, neuroendocrine signaling, and stress responses. Several epigenetic regulators, including <em>Tet2, Dnmt3a,</em> and <em>Apobec1</em>, exhibited metabolic state- and cold-dependent expression, and TF-motif analyses highlighted roles for AhrArnt and Foxn1. In vitro assays confirmed that DNA methylation influences expression of thermogenic genes.</div></div><div><h3>Conclusion</h3><div>These findings provide the first evidence that the epigenetic cold response of BAT differs by metabolic condition. BAT remodeling is shaped by coordinated transcriptional and epigenetic mechanisms integrating environmental and metabolic cues.</div></div>","PeriodicalId":18765,"journal":{"name":"Molecular Metabolism","volume":"104 ","pages":"Article 102315"},"PeriodicalIF":6.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145896141","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-01DOI: 10.1016/j.molmet.2025.102304
Shiqian Chen , Carolina B. Lobato , Carissa Wong , Yusman Manchanda , Katrina Viloria , Iona Davies , Daniel B. Andersen , Julia Ast , Kyle W. Sloop , David J. Hodson , Johannes Broichhagen , Steve Bloom , Jens J. Holst , Tricia Tan , Alejandra Tomas , Ben Jones
Internalisation of G protein-coupled receptors (GPCRs) can contribute to altered cellular responses by directing signalling from non-canonical locations, such as endosomes. If signalling processes are locally constrained, active receptors in different subcellular locations could produce different downstream effects. This phenomenon may be relevant to the optimal targeting of the glucagon-like peptide-1 receptor (GLP-1R), a type 2 diabetes and obesity target GPCR for which several ligands with varying internalisation tendency have been discovered. To investigate, we compared the signalling localisation effects of two prototypical GLP-1RAs with opposite signal bias and effects on GLP-1R trafficking: exendin-asp3 (ExD3), a full agonist that drives rapid internalisation, and exendin-phe1 (ExF1), which shows much slower internalisation. After using bioorthogonal labelling and fluorescent agonist conjugates to verify the divergent trafficking patterns of ExF1 and ExD3 in β-cell lines and primary pancreatic islets, we used live cell biosensors to monitor signalling at different subcellular locations. This revealed that cAMP/PKA/ERK signalling in β-cells is in fact distributed widely across the cell over short- (<5 min) and medium-term (up to 60 min) stimulation at pharmacological (>10 pM) concentrations, with no major differences in signal localisation that could be linked to internalised versus cell surface-bound GLP-1R. Moreover, washout experiments highlighted that, whilst fast-internalising ExD3 shows much greater accumulation and binding to GLP-1R in endosomes than slow-internalising ExF1, it is a rather inefficient driver of both cAMP production in β-cells and insulin secretion from perfused rat pancreata. These data provide a greater understanding of the cellular effects of biased GLP-1R agonism.
{"title":"Spatially diffuse cAMP signalling with oppositely biased GLP-1 receptor agonists in β-cells despite differences in receptor localisation","authors":"Shiqian Chen , Carolina B. Lobato , Carissa Wong , Yusman Manchanda , Katrina Viloria , Iona Davies , Daniel B. Andersen , Julia Ast , Kyle W. Sloop , David J. Hodson , Johannes Broichhagen , Steve Bloom , Jens J. Holst , Tricia Tan , Alejandra Tomas , Ben Jones","doi":"10.1016/j.molmet.2025.102304","DOIUrl":"10.1016/j.molmet.2025.102304","url":null,"abstract":"<div><div>Internalisation of G protein-coupled receptors (GPCRs) can contribute to altered cellular responses by directing signalling from non-canonical locations, such as endosomes. If signalling processes are locally constrained, active receptors in different subcellular locations could produce different downstream effects. This phenomenon may be relevant to the optimal targeting of the glucagon-like peptide-1 receptor (GLP-1R), a type 2 diabetes and obesity target GPCR for which several ligands with varying internalisation tendency have been discovered. To investigate, we compared the signalling localisation effects of two prototypical GLP-1RAs with opposite signal bias and effects on GLP-1R trafficking: exendin-asp3 (ExD3), a full agonist that drives rapid internalisation, and exendin-phe1 (ExF1), which shows much slower internalisation. After using bioorthogonal labelling and fluorescent agonist conjugates to verify the divergent trafficking patterns of ExF1 and ExD3 in β-cell lines and primary pancreatic islets, we used live cell biosensors to monitor signalling at different subcellular locations. This revealed that cAMP/PKA/ERK signalling in β-cells is in fact distributed widely across the cell over short- (<5 min) and medium-term (up to 60 min) stimulation at pharmacological (>10 pM) concentrations, with no major differences in signal localisation that could be linked to internalised <em>versus</em> cell surface-bound GLP-1R. Moreover, washout experiments highlighted that, whilst fast-internalising ExD3 shows much greater accumulation and binding to GLP-1R in endosomes than slow-internalising ExF1, it is a rather inefficient driver of both cAMP production in β-cells and insulin secretion from perfused rat pancreata. These data provide a greater understanding of the cellular effects of biased GLP-1R agonism.</div></div>","PeriodicalId":18765,"journal":{"name":"Molecular Metabolism","volume":"103 ","pages":"Article 102304"},"PeriodicalIF":6.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145757158","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2026-01-01DOI: 10.1016/j.molmet.2025.102313
Irmak Gezginer , Giulia Mazzini , Christelle Le Foll , Diana Kindler , Thomas A. Lutz , Daniel Razansky
Obesity remains a major global health challenge, yet the brain-wide effects of hormones regulating appetite remain incompletely understood. Amylin, co-secreted with insulin by pancreatic β-cells, promotes satiation and is a promising therapeutic target for metabolic disorders. While its receptor distribution is well-characterized, its influence on large-scale neural dynamics is unknown. Here, resting-state fMRI was used to map time-resolved connectivity changes following peripheral amylin administration in wild-type (WT) and receptor activity-modifying protein 1/3 knockout (RAMP1/3 KO) mice. In WT animals, amylin triggered rapid and transient network reconfigurations, engaging canonical satiation hubs such as the area postrema and parabrachial nucleus, and extending to sensory-integrative areas including the inferior colliculus and insular cortex. Early hindbrain responses propagated to hypothalamic, thalamic, and mesolimbic circuits implicated in appetite and reward. These effects, along with amylin-driven modulation of large-scale networks and low-frequency oscillations, were absent in KO mice. The findings position amylin as a potent modulator of distributed brain circuits, offering a framework for targeted obesity treatments.
{"title":"Pancreatic amylin dynamically reconfigures distributed brain networks governing appetite regulation in mice","authors":"Irmak Gezginer , Giulia Mazzini , Christelle Le Foll , Diana Kindler , Thomas A. Lutz , Daniel Razansky","doi":"10.1016/j.molmet.2025.102313","DOIUrl":"10.1016/j.molmet.2025.102313","url":null,"abstract":"<div><div>Obesity remains a major global health challenge, yet the brain-wide effects of hormones regulating appetite remain incompletely understood. Amylin, co-secreted with insulin by pancreatic β-cells, promotes satiation and is a promising therapeutic target for metabolic disorders. While its receptor distribution is well-characterized, its influence on large-scale neural dynamics is unknown. Here, resting-state fMRI was used to map time-resolved connectivity changes following peripheral amylin administration in wild-type (WT) and receptor activity-modifying protein 1/3 knockout (RAMP1/3 KO) mice. In WT animals, amylin triggered rapid and transient network reconfigurations, engaging canonical satiation hubs such as the area postrema and parabrachial nucleus, and extending to sensory-integrative areas including the inferior colliculus and insular cortex. Early hindbrain responses propagated to hypothalamic, thalamic, and mesolimbic circuits implicated in appetite and reward. These effects, along with amylin-driven modulation of large-scale networks and low-frequency oscillations, were absent in KO mice. The findings position amylin as a potent modulator of distributed brain circuits, offering a framework for targeted obesity treatments.</div></div>","PeriodicalId":18765,"journal":{"name":"Molecular Metabolism","volume":"103 ","pages":"Article 102313"},"PeriodicalIF":6.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145827245","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-26DOI: 10.1016/j.molmet.2025.102314
April E. Hartley , Katyayani Sukhavasi , Sile Hu , Matthew Traylor , Mar Gonzalez-Ramirez , Kristian Ebbesen Hanghøj , Husain Talukdar , Arno Ruusalepp , Ellen Björkegren , Johan LM. Björkegren , Joanna MM. Howson , Yalda Jamshidi
Understanding tissue-specific mechanisms of protein regulation gives crucial insights into cardiometabolic disease and informs drug discovery. Most proteomic studies have primarily concentrated on plasma, overlooking tissue-specific effects. Utilizing Olink technology, we assessed relative protein levels across plasma and tissue (aortic wall, mammary artery, liver, and skeletal muscle) from the STARNET cohort: 284 individuals with a high prevalence of coronary artery disease (CAD). We identified 608 cis protein quantitative trait loci (pQTLs), primarily in plasma, reflecting greater protein variability. Of 190 proteins with cis-pQTLs in non-plasma tissues, 50% also had plasma pQTLs, validating Olink technology in these tissues while reinforcing the relevance of plasma data for understanding protein regulation. To identify potential mechanistic pathways linking genetic variants to clinical traits, we performed Bayesian colocalization and Mendelian randomization. These analyses revealed shared genetic regulation between tissues at the gene expression and protein level, and key cardiometabolic traits including low-density lipoprotein (LDL), high-density lipoprotein (HDL), and triglycerides. Notably, analyses provide further support to SORT1 and PSRC1 gene and protein expression having liver-specific influences on CAD risk and lipid profiles. We also observed distinct genetic regulation of gene expression and protein within the same tissues, underscoring the value of tissue proteomics for therapeutic insights.
{"title":"Deciphering tissue-specific protein regulation for insights into cardiometabolic disease","authors":"April E. Hartley , Katyayani Sukhavasi , Sile Hu , Matthew Traylor , Mar Gonzalez-Ramirez , Kristian Ebbesen Hanghøj , Husain Talukdar , Arno Ruusalepp , Ellen Björkegren , Johan LM. Björkegren , Joanna MM. Howson , Yalda Jamshidi","doi":"10.1016/j.molmet.2025.102314","DOIUrl":"10.1016/j.molmet.2025.102314","url":null,"abstract":"<div><div>Understanding tissue-specific mechanisms of protein regulation gives crucial insights into cardiometabolic disease and informs drug discovery. Most proteomic studies have primarily concentrated on plasma, overlooking tissue-specific effects. Utilizing Olink technology, we assessed relative protein levels across plasma and tissue (aortic wall, mammary artery, liver, and skeletal muscle) from the STARNET cohort: 284 individuals with a high prevalence of coronary artery disease (CAD). We identified 608 <em>cis</em> protein quantitative trait loci (pQTLs), primarily in plasma, reflecting greater protein variability. Of 190 proteins with <em>cis</em>-pQTLs in non-plasma tissues, 50% also had plasma pQTLs, validating Olink technology in these tissues while reinforcing the relevance of plasma data for understanding protein regulation. To identify potential mechanistic pathways linking genetic variants to clinical traits, we performed Bayesian colocalization and Mendelian randomization. These analyses revealed shared genetic regulation between tissues at the gene expression and protein level, and key cardiometabolic traits including low-density lipoprotein (LDL), high-density lipoprotein (HDL), and triglycerides. Notably, analyses provide further support to SORT1 and PSRC1 gene and protein expression having liver-specific influences on CAD risk and lipid profiles. We also observed distinct genetic regulation of gene expression and protein within the same tissues, underscoring the value of tissue proteomics for therapeutic insights.</div></div>","PeriodicalId":18765,"journal":{"name":"Molecular Metabolism","volume":"104 ","pages":"Article 102314"},"PeriodicalIF":6.6,"publicationDate":"2025-12-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145850202","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-19DOI: 10.1016/j.molmet.2025.102310
Melissa A. Fulham , John D. Griffin , Sylvie Perez , Zhongyuan Sun , Natalie A. Daurio , Gang Xing , Michelle F. Clasquin , Melissa R. Miller , Craig L. Hyde , Scott P. Kelly , Magalie Boucher , Rachel Poskanzer , Ramya Gamini , Evanthia Pashos , Ying Zhang , Elaine Kuang , Josh Fienman , Kendra K. Bence , Gregory J. Tesz
Objectives
Hereditary fructose intolerance (HFI), caused by Aldolase B deficiency, is a rare genetic disorder where fructose exposure leads to severe metabolic pathologies including Type-2 diabetes and liver steatosis. Despite adhering to fructose-free diets, some individuals still present with disease. Using a rat model of HFI we demonstrate that fructose independent pathologies exist and identify the molecular pathways driving disease.
Methods
Aldob was deleted in Sprague Dawley rats using CRIPSR/Cas9 (AldoB-KO). Phenotypic, metabolomic and transcriptomic studies were conducted to identify mechanisms promoting fructose-independent pathologies. Potential molecular causes were tested using pharmacologic inhibitors and ASOs.
Results
Deletion of Aldob caused hepatic steatosis, fibrosis and stunted growth in rats weaned on low fructose chow recapitulating human HFI. On fructose-free chow, AldoB-KO rats were phenotypically normal. However, upon fasting, male and female AldoB-KO rats developed hepatic steatosis and hyperlipidemia due to impaired fatty acid oxidation (FAOx) and elevated de novo lipogenesis (DNL). Transcriptional and metabolomic profiling revealed increased hepatic Carbohydrate Response Element Binding Protein (ChREBP) activation in AldoB-KO rats due to glycolytic metabolite accumulation caused by impaired gluconeogenesis. Treatment with Acetyl-CoA Carboxylase (ACC) and Diacylglycerol Acyl Transferase 2 (DGAT2) inhibitors reduced hepatic lipids and plasma triglycerides in AldoB-KO rats. Finally, using electronic health records we observed increased metabolic dysfunction-associated steatohepatitis (MASH) diagnosis in individuals with HFI.
Conclusions
Aldob deletion caused fructose-independent hyperlipidemia and steatosis upon fasting in rats. Individuals with HFI may have risk for hepatic disease and hyperlipidemia even upon fructose abstinence suggesting additional therapies may be needed to mitigate disease.
{"title":"Impaired hepatic metabolism in Hereditary Fructose Intolerance confers fructose-independent risk for steatosis and hypertriglyceridemia","authors":"Melissa A. Fulham , John D. Griffin , Sylvie Perez , Zhongyuan Sun , Natalie A. Daurio , Gang Xing , Michelle F. Clasquin , Melissa R. Miller , Craig L. Hyde , Scott P. Kelly , Magalie Boucher , Rachel Poskanzer , Ramya Gamini , Evanthia Pashos , Ying Zhang , Elaine Kuang , Josh Fienman , Kendra K. Bence , Gregory J. Tesz","doi":"10.1016/j.molmet.2025.102310","DOIUrl":"10.1016/j.molmet.2025.102310","url":null,"abstract":"<div><h3>Objectives</h3><div>Hereditary fructose intolerance (HFI), caused by Aldolase B deficiency, is a rare genetic disorder where fructose exposure leads to severe metabolic pathologies including Type-2 diabetes and liver steatosis. Despite adhering to fructose-free diets, some individuals still present with disease. Using a rat model of HFI we demonstrate that fructose independent pathologies exist and identify the molecular pathways driving disease.</div></div><div><h3>Methods</h3><div><em>Aldob</em> was deleted in Sprague Dawley rats using CRIPSR/Cas9 (AldoB-KO). Phenotypic, metabolomic and transcriptomic studies were conducted to identify mechanisms promoting fructose-independent pathologies. Potential molecular causes were tested using pharmacologic inhibitors and ASOs.</div></div><div><h3>Results</h3><div>Deletion of <em>Aldob</em> caused hepatic steatosis, fibrosis and stunted growth in rats weaned on low fructose chow recapitulating human HFI. On fructose-free chow, AldoB-KO rats were phenotypically normal. However, upon fasting, male and female AldoB-KO rats developed hepatic steatosis and hyperlipidemia due to impaired fatty acid oxidation (FAOx) and elevated de novo lipogenesis (DNL). Transcriptional and metabolomic profiling revealed increased hepatic Carbohydrate Response Element Binding Protein (ChREBP) activation in AldoB-KO rats due to glycolytic metabolite accumulation caused by impaired gluconeogenesis. Treatment with Acetyl-CoA Carboxylase (ACC) and Diacylglycerol Acyl Transferase 2 (DGAT2) inhibitors reduced hepatic lipids and plasma triglycerides in AldoB-KO rats. Finally, using electronic health records we observed increased metabolic dysfunction-associated steatohepatitis (MASH) diagnosis in individuals with HFI.</div></div><div><h3>Conclusions</h3><div><em>Aldob</em> deletion caused fructose-independent hyperlipidemia and steatosis upon fasting in rats. Individuals with HFI may have risk for hepatic disease and hyperlipidemia even upon fructose abstinence suggesting additional therapies may be needed to mitigate disease.</div></div>","PeriodicalId":18765,"journal":{"name":"Molecular Metabolism","volume":"104 ","pages":"Article 102310"},"PeriodicalIF":6.6,"publicationDate":"2025-12-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145805074","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-17DOI: 10.1016/j.molmet.2025.102309
William De Nardo , Jacqueline Bayliss , Sheik Nadeem Elahee Doomun , Olivia Lee , Paula M. Miotto , Natasha D. Suriani , Shuai Nie , Michael Leeming , Diego A. Miranda , David P. De Souza , Matthew J. Watt
Abstract/objective
Metabolic associated steatotic liver disease (MASLD) is the most prevalent liver disorder and a major risk factor for hepatic fibrosis. Activated hepatic stellate cells (HSCs) are the primary source of collagen production in the liver, contributing to fibrosis. However, the mechanisms by which HSCs reprogram their metabolism to support sustained collagen production, particularly in a lipid-rich environment such as MASLD, remain inadequately understood. In this study, we investigated the effect of extracellular fatty acids on HSC substrate metabolism, HSC activation, and collagen synthesis.
Methods
Immortalized human HSCs (LX-2 cells) were cultured with or without transforming growth factor-beta 1 (TGF-β1) and varying concentrations of palmitate or oleate. Cellular lipid composition was assessed by mass spectrometry lipidomics. Fatty acid metabolism was assessed using radiometric techniques and isotopic labelling experiments using 13C-glucose or 13C-palmitate. HSC activation was assessed by measuring ACTA2, TGFB1, and COL1A1 mRNA levels and collagen secretion by ELISA.
Results
TGF-β1 reduced the abundance of many lipid types in LX-2 cells. Exogenous palmitate did not increase HSC activation, as determined by ACTA2, TGFB1, COL1A1 mRNA levels. Palmitate potentiated TGF-β1 induced collagen secretion but not in the presence of oleate. Palmitate reduced glucose incorporation into glycine in activated HSCs and induced a reciprocal increase in palmitate incorporation into glycine, most likely via carbons derived from TCA cycle intermediates. Pharmacological inhibition of fatty acid uptake reduced TGF-β1-mediated collagen secretion.
Conclusions
These results suggest that in activated HSCs, palmitate oxidation is reduced and that TCA cycle intermediates derived from palmitate are used as carbon sources for amino acid production that supports collagen synthesis and secretion.
{"title":"Effect of free fatty acids on TGF-β1 mediated fibrogenesis in hepatic stellate cells","authors":"William De Nardo , Jacqueline Bayliss , Sheik Nadeem Elahee Doomun , Olivia Lee , Paula M. Miotto , Natasha D. Suriani , Shuai Nie , Michael Leeming , Diego A. Miranda , David P. De Souza , Matthew J. Watt","doi":"10.1016/j.molmet.2025.102309","DOIUrl":"10.1016/j.molmet.2025.102309","url":null,"abstract":"<div><h3>Abstract/objective</h3><div>Metabolic associated steatotic liver disease (MASLD) is the most prevalent liver disorder and a major risk factor for hepatic fibrosis. Activated hepatic stellate cells (HSCs) are the primary source of collagen production in the liver, contributing to fibrosis. However, the mechanisms by which HSCs reprogram their metabolism to support sustained collagen production, particularly in a lipid-rich environment such as MASLD, remain inadequately understood. In this study, we investigated the effect of extracellular fatty acids on HSC substrate metabolism, HSC activation, and collagen synthesis.</div></div><div><h3>Methods</h3><div>Immortalized human HSCs (LX-2 cells) were cultured with or without transforming growth factor-beta 1 (TGF-β1) and varying concentrations of palmitate or oleate. Cellular lipid composition was assessed by mass spectrometry lipidomics. Fatty acid metabolism was assessed using radiometric techniques and isotopic labelling experiments using <sup>13</sup>C-glucose or <sup>13</sup>C-palmitate. HSC activation was assessed by measuring <em>ACTA2, TGFB1, and COL1A1</em> mRNA levels and collagen secretion by ELISA.</div></div><div><h3>Results</h3><div>TGF-β1 reduced the abundance of many lipid types in LX-2 cells. Exogenous palmitate did not increase HSC activation, as determined by <em>ACTA2, TGFB1, COL1A1</em> mRNA levels. Palmitate potentiated TGF-β1 induced collagen secretion but not in the presence of oleate. Palmitate reduced glucose incorporation into glycine in activated HSCs and induced a reciprocal increase in palmitate incorporation into glycine, most likely via carbons derived from TCA cycle intermediates. Pharmacological inhibition of fatty acid uptake reduced TGF-β1-mediated collagen secretion.</div></div><div><h3>Conclusions</h3><div>These results suggest that in activated HSCs, palmitate oxidation is reduced and that TCA cycle intermediates derived from palmitate are used as carbon sources for amino acid production that supports collagen synthesis and secretion.</div></div>","PeriodicalId":18765,"journal":{"name":"Molecular Metabolism","volume":"104 ","pages":"Article 102309"},"PeriodicalIF":6.6,"publicationDate":"2025-12-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145794426","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-16DOI: 10.1016/j.molmet.2025.102303
M. Yang , A. de Araujo , J. Shakir , I. Braga , R. Mendez-Hernandez , G.S.S. Tofani , A. Bali , J. de Lartigue , H. Song , J.E. McCutcheon , C.D. Morrison , G. de Lartigue
Animals adaptively adjust nutrient intake based on internal physiological need. Although protein deficiency elicits robust behavioral and endocrine responses, the sensory mechanisms that detect dietary protein and guide selective feeding remain incompletely understood. Here, we identify a population of vagal sensory neurons that respond selectively to intragastric protein and are required for adaptive regulation of protein intake. Using activity-dependent genetic labeling and in vivo calcium imaging, we show that these neurons are activated by dietary protein, exhibit enhanced responses in protein-restricted states, and are distinct from previously characterized calorie-sensing populations. Selective ablation of protein-responsive vagal sensory neurons disrupts the ability to adapt eating behavior to internal protein need, blunts motivation to work for protein rewards, and prevents behavioral updating following protein repletion. These neurons also mediate protein-specific satiety, limiting further protein intake without affecting carbohydrate consumption. Notably, protein preference is suppressed under mild caloric restriction, indicating that caloric and amino acid needs are hierarchically organized and likely monitored by separate interoceptive systems. Our findings reveal a novel vagal circuit that integrates internal protein status with nutrient-specific cues to guide adaptive protein appetite and maintain amino acid homeostasis.
{"title":"Vagal sensory neurons encode internal protein status to guide eating","authors":"M. Yang , A. de Araujo , J. Shakir , I. Braga , R. Mendez-Hernandez , G.S.S. Tofani , A. Bali , J. de Lartigue , H. Song , J.E. McCutcheon , C.D. Morrison , G. de Lartigue","doi":"10.1016/j.molmet.2025.102303","DOIUrl":"10.1016/j.molmet.2025.102303","url":null,"abstract":"<div><div>Animals adaptively adjust nutrient intake based on internal physiological need. Although protein deficiency elicits robust behavioral and endocrine responses, the sensory mechanisms that detect dietary protein and guide selective feeding remain incompletely understood. Here, we identify a population of vagal sensory neurons that respond selectively to intragastric protein and are required for adaptive regulation of protein intake. Using activity-dependent genetic labeling and in vivo calcium imaging, we show that these neurons are activated by dietary protein, exhibit enhanced responses in protein-restricted states, and are distinct from previously characterized calorie-sensing populations. Selective ablation of protein-responsive vagal sensory neurons disrupts the ability to adapt eating behavior to internal protein need, blunts motivation to work for protein rewards, and prevents behavioral updating following protein repletion. These neurons also mediate protein-specific satiety, limiting further protein intake without affecting carbohydrate consumption. Notably, protein preference is suppressed under mild caloric restriction, indicating that caloric and amino acid needs are hierarchically organized and likely monitored by separate interoceptive systems. Our findings reveal a novel vagal circuit that integrates internal protein status with nutrient-specific cues to guide adaptive protein appetite and maintain amino acid homeostasis.</div></div>","PeriodicalId":18765,"journal":{"name":"Molecular Metabolism","volume":"104 ","pages":"Article 102303"},"PeriodicalIF":6.6,"publicationDate":"2025-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145781567","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-16DOI: 10.1016/j.molmet.2025.102305
Julius E R Grothen, Jaime M Martinez, Nikos Sidiropoulos, Lucas Massier, Danae Zareifi, Jiawei Zhong, Ida Davidsen, Jette W Platou, Jette Mandelbaum, Pia Rothe, Henning Hvid, Mads Grønborg, Christian Toft Madsen, Jens M Bruun, Mikael Rydén, Niklas Mejhert, Jørn W Helge, Zachary Gerhart-Hines, Thomas Å Pedersen
Background: Combination of increased physical exercise and hypocaloric diet has long been recognized to improve cardiometabolic health and adipose tissue function, including lipid turnover. How such lifestyle interventions mediate benefits at the cellular level remains unknown. Given the critical role of subcutaneous white adipose tissue (scWAT) to systemic metabolic homeostasis, we set out to interrogate how exercise and diet lifestyle intervention impacted scWAT in individuals living with obesity, with a particular focus on lipolytic capacity and cell-specific gene profiling.
Methods: Single nuclei RNA sequencing (snRNAseq) was performed on cryopreserved scWAT biopsies originally collected before and after lifestyle intervention, involving regular exercise and hypocaloric diet in obese individuals. Findings on regulation of lipolysis in adipocytes were followed up with meta-analysis of clinical studies and pharmacological experiments in mature human adipocytes.
Results: snRNAseq analysis revealed intervention-induced changes in all scWAT cell-types. In adipocytes genes linked to protein and organelle turnover, branch chain amino acid catabolism, and lipolytic control were most significantly regulated. We identified a cell autonomous brake on adipocyte lipolysis via the neuropeptide Y receptor 1 (NPY1R). Expression of adipocyte NPY1R was reduced after weight loss and correlated positively with body fat percentage and body mass index. Findings were confirmed in meta-analysis across 23 studies. Finally, we found a negative correlation between NPY1R and beta-adrenergic-induced lipolysis and that NPY dose-dependently attenuated lipolysis and cAMP-signaling in primary human subcutaneous adipocytes.
Conclusions: Our work suggests that decreases in adipocyte NPY1R during weight loss boost lipolytic capacity and contribute to improved systemic cardiometabolic health.
{"title":"Single cell transcriptomics of human weight loss links adipocyte NPY1R to control of lipolysis.","authors":"Julius E R Grothen, Jaime M Martinez, Nikos Sidiropoulos, Lucas Massier, Danae Zareifi, Jiawei Zhong, Ida Davidsen, Jette W Platou, Jette Mandelbaum, Pia Rothe, Henning Hvid, Mads Grønborg, Christian Toft Madsen, Jens M Bruun, Mikael Rydén, Niklas Mejhert, Jørn W Helge, Zachary Gerhart-Hines, Thomas Å Pedersen","doi":"10.1016/j.molmet.2025.102305","DOIUrl":"10.1016/j.molmet.2025.102305","url":null,"abstract":"<p><strong>Background: </strong>Combination of increased physical exercise and hypocaloric diet has long been recognized to improve cardiometabolic health and adipose tissue function, including lipid turnover. How such lifestyle interventions mediate benefits at the cellular level remains unknown. Given the critical role of subcutaneous white adipose tissue (scWAT) to systemic metabolic homeostasis, we set out to interrogate how exercise and diet lifestyle intervention impacted scWAT in individuals living with obesity, with a particular focus on lipolytic capacity and cell-specific gene profiling.</p><p><strong>Methods: </strong>Single nuclei RNA sequencing (snRNAseq) was performed on cryopreserved scWAT biopsies originally collected before and after lifestyle intervention, involving regular exercise and hypocaloric diet in obese individuals. Findings on regulation of lipolysis in adipocytes were followed up with meta-analysis of clinical studies and pharmacological experiments in mature human adipocytes.</p><p><strong>Results: </strong>snRNAseq analysis revealed intervention-induced changes in all scWAT cell-types. In adipocytes genes linked to protein and organelle turnover, branch chain amino acid catabolism, and lipolytic control were most significantly regulated. We identified a cell autonomous brake on adipocyte lipolysis via the neuropeptide Y receptor 1 (NPY1R). Expression of adipocyte NPY1R was reduced after weight loss and correlated positively with body fat percentage and body mass index. Findings were confirmed in meta-analysis across 23 studies. Finally, we found a negative correlation between NPY1R and beta-adrenergic-induced lipolysis and that NPY dose-dependently attenuated lipolysis and cAMP-signaling in primary human subcutaneous adipocytes.</p><p><strong>Conclusions: </strong>Our work suggests that decreases in adipocyte NPY1R during weight loss boost lipolytic capacity and contribute to improved systemic cardiometabolic health.</p>","PeriodicalId":18765,"journal":{"name":"Molecular Metabolism","volume":" ","pages":"102305"},"PeriodicalIF":6.6,"publicationDate":"2025-12-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145781569","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-15DOI: 10.1016/j.molmet.2025.102308
Nandini K. Doshi , Tristan Pesaresi , Trishya Pagadala , William Dion , Yang Zhang , Natalie L. David , Tânia Amorim , Wenjia Wang , G.V. Naveen Kumar , Bokai Zhu , Silvia Liu , Parth Patwari , Pouneh K. Fazeli , Matthew L. Steinhauser
Sterile inflammation is associated with a broad range of metabolic stressors including both dietary excess and prolonged fasting. In a 10-day human fasting study, we previously identified a surge in the circulating inflammatory biomarker, C-reactive protein (CRP), which we leveraged in the current study to identify novel metabolic inflammatory correlates. With a variety of longitudinal metabolic variables as input, including metabolomics, we identified branched chain amino acids (BCAA) as the top candidate inflammatory correlate. We then used in vitro myeloid/macrophage culture and in vivo murine models to test BCAA as a determinant of inflammatory signaling. Short-term exposure to BCAA alone had modest effects on a variety of immune readouts; however, when coupled with a second stimulus, such as exposure to endotoxin or when administered to diet-induced obese mice, members of the JAK/STAT/cytokine signaling pathways were augmented on the transcriptional level by concurrent BCAA administration in multiple tissues, including visceral adipose and liver. The modifying effect of BCAA on inflammatory stressors translated into increased levels of circulating inflammatory cytokines. Collectively, these data position BCAA as an immune priming factor, a potential mechanism underlying the well-established association between circulating BCAA and diverse diseases of aging.
{"title":"Branched chain amino acids prime metabolic inflammation","authors":"Nandini K. Doshi , Tristan Pesaresi , Trishya Pagadala , William Dion , Yang Zhang , Natalie L. David , Tânia Amorim , Wenjia Wang , G.V. Naveen Kumar , Bokai Zhu , Silvia Liu , Parth Patwari , Pouneh K. Fazeli , Matthew L. Steinhauser","doi":"10.1016/j.molmet.2025.102308","DOIUrl":"10.1016/j.molmet.2025.102308","url":null,"abstract":"<div><div>Sterile inflammation is associated with a broad range of metabolic stressors including both dietary excess and prolonged fasting. In a 10-day human fasting study, we previously identified a surge in the circulating inflammatory biomarker, C-reactive protein (CRP), which we leveraged in the current study to identify novel metabolic inflammatory correlates. With a variety of longitudinal metabolic variables as input, including metabolomics, we identified branched chain amino acids (BCAA) as the top candidate inflammatory correlate. We then used <em>in vitro</em> myeloid/macrophage culture and <em>in vivo</em> murine models to test BCAA as a determinant of inflammatory signaling. Short-term exposure to BCAA alone had modest effects on a variety of immune readouts; however, when coupled with a second stimulus, such as exposure to endotoxin or when administered to diet-induced obese mice, members of the JAK/STAT/cytokine signaling pathways were augmented on the transcriptional level by concurrent BCAA administration in multiple tissues, including visceral adipose and liver. The modifying effect of BCAA on inflammatory stressors translated into increased levels of circulating inflammatory cytokines. Collectively, these data position BCAA as an immune priming factor, a potential mechanism underlying the well-established association between circulating BCAA and diverse diseases of aging.</div></div>","PeriodicalId":18765,"journal":{"name":"Molecular Metabolism","volume":"104 ","pages":"Article 102308"},"PeriodicalIF":6.6,"publicationDate":"2025-12-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145775023","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2025-12-09DOI: 10.1016/j.molmet.2025.102299
Ethan C. Fein , Sarmistha Mukherjee , Joseph A. Baur , Patrick Seale
Brown adipose tissue (BAT) dissipates energy as heat in response to β-adrenergic signaling induced by the sympathetic nervous system (SNS). While this pathway is essential for the cold-induced remodeling and metabolic activity of BAT, its role in developmental programming is unclear. Here, we show that brown adipocytes acquire thermogenic identity during embryogenesis independently of sympathetic innervation and β-adrenergic signaling. Genetic sympathectomy or disrupted β-adrenergic signaling had minimal effects on thermogenic gene expression or tissue morphology during either embryonic or postnatal BAT development in the absence of cold stress. Functional analyses revealed that the SNS is likely required for circulatory support of BAT activity during β-adrenergic stimulation but not for the development of the thermogenic capacity of BAT itself. These findings demonstrate that developmental and cold-responsive BAT remodeling are mechanistically distinct processes. Defining the molecular programs that drive BAT development may reveal new strategies to enhance BAT formation and function without relying on β-adrenergic stimulation.
{"title":"The innate thermogenic capacity of brown adipose tissue develops independently of sympathetic signaling","authors":"Ethan C. Fein , Sarmistha Mukherjee , Joseph A. Baur , Patrick Seale","doi":"10.1016/j.molmet.2025.102299","DOIUrl":"10.1016/j.molmet.2025.102299","url":null,"abstract":"<div><div>Brown adipose tissue (BAT) dissipates energy as heat in response to β-adrenergic signaling induced by the sympathetic nervous system (SNS). While this pathway is essential for the cold-induced remodeling and metabolic activity of BAT, its role in developmental programming is unclear. Here, we show that brown adipocytes acquire thermogenic identity during embryogenesis independently of sympathetic innervation and β-adrenergic signaling. Genetic sympathectomy or disrupted β-adrenergic signaling had minimal effects on thermogenic gene expression or tissue morphology during either embryonic or postnatal BAT development in the absence of cold stress. Functional analyses revealed that the SNS is likely required for circulatory support of BAT activity during β-adrenergic stimulation but not for the development of the thermogenic capacity of BAT itself. These findings demonstrate that developmental and cold-responsive BAT remodeling are mechanistically distinct processes. Defining the molecular programs that drive BAT development may reveal new strategies to enhance BAT formation and function without relying on β-adrenergic stimulation.</div></div>","PeriodicalId":18765,"journal":{"name":"Molecular Metabolism","volume":"103 ","pages":"Article 102299"},"PeriodicalIF":6.6,"publicationDate":"2025-12-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145743408","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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