Pub Date : 2024-11-19DOI: 10.1016/j.molmet.2024.102066
Sean Y. Ng , Andrew I. Mikhail , Stephanie R. Mattina , Salah A. Mohammed , Shahzeb K. Khan , Eric M. Desjardins , Changhyun Lim , Stuart M. Phillips , Gregory R. Steinberg , Vladimir Ljubicic
Objective
The molecular mechanisms underlying the maintenance and adaptability of the neuromuscular junction (NMJ) remain poorly understood. This study aimed to investigate the role of AMP-activated protein kinase (AMPK) as a key regulator of NMJ stability and plasticity.
Method
A comprehensive, multifaceted approach was employed, integrating genetic, physiological, and pharmacological methodologies to elucidate the role of skeletal muscle AMPK in modulating the neuromuscular synapse.
Results
Our findings reveal an increased abundance of AMPK transcripts within the NMJ and an age-associated decline in AMPK activity and synapse-specific mitochondrial gene expression. Young mice null for skeletal muscle AMPK displayed a neuromuscular phenotype akin to aged animals. Pharmacological AMPK stimulation facilitated its localization in subsynaptic myonuclei, preceded the induction of several NMJ-related transcripts, and enhanced myotube acetylcholine receptor clustering. Exercise-induced AMPK activation in mouse muscle elicited a broad NMJ-related gene response, consistent with human exercise data.
Conclusions
These findings highlight a critical role for AMPK in the maintenance and remodeling of the NMJ, highlighting its potential as a therapeutic target for age-related and neuromuscular disorders.
{"title":"AMPK regulates the maintenance and remodelling of the neuromuscular junction","authors":"Sean Y. Ng , Andrew I. Mikhail , Stephanie R. Mattina , Salah A. Mohammed , Shahzeb K. Khan , Eric M. Desjardins , Changhyun Lim , Stuart M. Phillips , Gregory R. Steinberg , Vladimir Ljubicic","doi":"10.1016/j.molmet.2024.102066","DOIUrl":"10.1016/j.molmet.2024.102066","url":null,"abstract":"<div><h3>Objective</h3><div>The molecular mechanisms underlying the maintenance and adaptability of the neuromuscular junction (NMJ) remain poorly understood. This study aimed to investigate the role of AMP-activated protein kinase (AMPK) as a key regulator of NMJ stability and plasticity.</div></div><div><h3>Method</h3><div>A comprehensive, multifaceted approach was employed, integrating genetic, physiological, and pharmacological methodologies to elucidate the role of skeletal muscle AMPK in modulating the neuromuscular synapse.</div></div><div><h3>Results</h3><div>Our findings reveal an increased abundance of AMPK transcripts within the NMJ and an age-associated decline in AMPK activity and synapse-specific mitochondrial gene expression. Young mice null for skeletal muscle AMPK displayed a neuromuscular phenotype akin to aged animals. Pharmacological AMPK stimulation facilitated its localization in subsynaptic myonuclei, preceded the induction of several NMJ-related transcripts, and enhanced myotube acetylcholine receptor clustering. Exercise-induced AMPK activation in mouse muscle elicited a broad NMJ-related gene response, consistent with human exercise data.</div></div><div><h3>Conclusions</h3><div>These findings highlight a critical role for AMPK in the maintenance and remodeling of the NMJ, highlighting its potential as a therapeutic target for age-related and neuromuscular disorders.</div></div>","PeriodicalId":18765,"journal":{"name":"Molecular Metabolism","volume":"91 ","pages":"Article 102066"},"PeriodicalIF":7.0,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142687727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-19DOI: 10.1016/j.molmet.2024.102068
Md Shahjalal H. Khan , Sora Q. Kim , Robert C. Ross , Florina Corpodean , Redin A. Spann , Diana A. Albarado , Sun O. Fernandez-Kim , Blaise Clarke , Hans-Rudolf Berthoud , Heike Münzberg , David H. McDougal , Yanlin He , Sangho Yu , Vance L. Albaugh , Paul L. Soto , Christopher D. Morrison
Objective
Dietary protein restriction induces adaptive changes in food preference, increasing protein consumption over carbohydrates or fat. We investigated whether motivation and reward signaling underpin these preferences.
Methods and Results
In an operant task, protein-restricted male mice responded more for liquid protein rewards, but not carbohydrate, fat, or sweet rewards compared to non-restricted mice. When the number of responses required to access protein reward varied, protein-restricted mice exhibited higher operant responses at moderate to high response requirements. The protein restriction-induced increase in operant responding for protein was absent in Fgf21-KO mice and mice with neuron-specific deletion of the FGF21 co-receptor beta-Klotho (KlbCam2ka). Fiber photometry recording of VTA dopamine neurons revealed that oral delivery of maltodextrin triggered a larger dopamine neuron activation than casein in control diet-fed mice, while casein triggered a larger activation in low-protein diet-fed mice. This restriction-induced shift in nutrient-specific VTA dopamine signaling was lost in Fgf21-KO mice.
Conclusion
These data suggest that the increased FGF21 during protein restriction acts in the brain to induce a protein-specific appetite by specifically enhancing the reward value of protein-containing foods and the motivation to consume them.
{"title":"FGF21 acts in the brain to drive macronutrient-specific changes in behavioral motivation and brain reward signaling","authors":"Md Shahjalal H. Khan , Sora Q. Kim , Robert C. Ross , Florina Corpodean , Redin A. Spann , Diana A. Albarado , Sun O. Fernandez-Kim , Blaise Clarke , Hans-Rudolf Berthoud , Heike Münzberg , David H. McDougal , Yanlin He , Sangho Yu , Vance L. Albaugh , Paul L. Soto , Christopher D. Morrison","doi":"10.1016/j.molmet.2024.102068","DOIUrl":"10.1016/j.molmet.2024.102068","url":null,"abstract":"<div><h3>Objective</h3><div>Dietary protein restriction induces adaptive changes in food preference, increasing protein consumption over carbohydrates or fat. We investigated whether motivation and reward signaling underpin these preferences.</div></div><div><h3>Methods and Results</h3><div>In an operant task, protein-restricted male mice responded more for liquid protein rewards, but not carbohydrate, fat, or sweet rewards compared to non-restricted mice. When the number of responses required to access protein reward varied, protein-restricted mice exhibited higher operant responses at moderate to high response requirements. The protein restriction-induced increase in operant responding for protein was absent in <em>Fgf21</em>-KO mice and mice with neuron-specific deletion of the FGF21 co-receptor beta-Klotho (Klb<sup>Cam2ka</sup>). Fiber photometry recording of VTA dopamine neurons revealed that oral delivery of maltodextrin triggered a larger dopamine neuron activation than casein in control diet-fed mice, while casein triggered a larger activation in low-protein diet-fed mice. This restriction-induced shift in nutrient-specific VTA dopamine signaling was lost in <em>Fgf21</em>-KO mice.</div></div><div><h3>Conclusion</h3><div>These data suggest that the increased FGF21 during protein restriction acts in the brain to induce a protein-specific appetite by specifically enhancing the reward value of protein-containing foods and the motivation to consume them.</div></div>","PeriodicalId":18765,"journal":{"name":"Molecular Metabolism","volume":"91 ","pages":"Article 102068"},"PeriodicalIF":7.0,"publicationDate":"2024-11-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142687729","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-16DOI: 10.1016/j.molmet.2024.102065
Tábatha de Oliveira Silva , Guilherme Lunardon , Caroline A. Lino , Amanda de Almeida Silva , Shiju Zhang , Maria Cláudia Costa Irigoyen , Yao Wei Lu , John D. Mably , Maria Luiza M. Barreto-Chaves , Da-Zhi Wang , Gabriela P. Diniz
Obesity is a major contributor to metabolic and cardiovascular disease. Although senescent cells have been shown to accumulate in adipose tissue, the role of senescence in obesity-induced metabolic disorders and in cardiac dysfunction is not yet clear; therefore, the therapeutic potential of managing senescence in obesity-related metabolic and cardiac disorders remains to be fully defined.
Objective
We investigated the beneficial effects of a senolytic cocktail (dasatinib and quercetin) on senescence and its influence on obesity-related parameters.
Methods and Results
We found that the increase in body weight and adiposity, glucose intolerance, insulin resistance, dyslipidemia, hyperleptinemia, and hepatic disorders which were induced by an obesogenic diet were alleviated by senolytic cocktail treatment in mice. Treatment with senolytic compounds eliminated senescent cells, counteracting the activation of the senescence program and DNA damage in white adipose tissue (WAT) observed with an obesogenic diet. Moreover, the senolytic cocktail prevented the brown adipose tissue (BAT) whitening and increased the expression of the thermogenic gene profile in BAT and pWAT. In the hearts of obese mice, senolytic combination abolished myocardial maladaptation, reducing the senescence-associated secretory phenotype (SASP) and DNA damage, repressing cardiac hypertrophy, and improving diastolic dysfunction. Additionally, we showed that treatment with the senolytic cocktail corrected gene expression programs associated with fatty acid metabolism, oxidative phosphorylation, the P53 pathway, and DNA repair, which were all downregulated in obese mice.
Conclusions
Collectively, these data suggest that a senolytic cocktail can prevent the activation of the senescence program in the heart and WAT and activate the thermogenic program in BAT. Our results suggest that targeting senescent cells may be a novel therapeutic strategy for alleviating obesity-related metabolic and cardiac disorders.
肥胖是代谢和心血管疾病的主要诱因。虽然衰老细胞已被证明会在脂肪组织中积聚,但衰老在肥胖诱发的代谢紊乱和心脏功能障碍中的作用尚不明确;因此,管理衰老在肥胖相关代谢紊乱和心脏功能障碍中的治疗潜力仍有待充分确定。我们研究了抗衰老鸡尾酒(达沙替尼和槲皮素)对衰老的有益作用及其对肥胖相关参数的影响。我们发现,肥胖饮食诱发的体重和脂肪增加、葡萄糖不耐受、胰岛素抵抗、血脂异常、高瘦素血症和肝功能紊乱等症状,在小鼠体内通过解老剂鸡尾酒治疗都得到了缓解。用衰老分解化合物治疗可消除衰老细胞,抵消肥胖饮食对衰老程序的激活和白色脂肪组织(WAT)的 DNA 损伤。此外,衰老鸡尾酒还能防止棕色脂肪组织(BAT)变白,并增加 BAT 和 pWAT 中致热基因的表达。在肥胖小鼠的心脏中,衰老素组合能消除心肌适应不良,减少衰老相关分泌表型(SASP)和DNA损伤,抑制心脏肥大,改善舒张功能障碍。此外,我们还发现,肥胖小鼠体内与脂肪酸代谢、氧化磷酸化、P53 通路和 DNA 修复相关的基因表达程序均被下调,而使用衰老鸡尾酒治疗可纠正这些基因表达程序。总之,这些数据表明,衰老鸡尾酒能阻止心脏和脂肪乳中衰老程序的激活,并激活脂肪乳中的生热程序。我们的研究结果表明,针对衰老细胞可能是缓解肥胖相关代谢和心脏疾病的一种新型治疗策略。
{"title":"Senescent cell depletion alleviates obesity-related metabolic and cardiac disorders","authors":"Tábatha de Oliveira Silva , Guilherme Lunardon , Caroline A. Lino , Amanda de Almeida Silva , Shiju Zhang , Maria Cláudia Costa Irigoyen , Yao Wei Lu , John D. Mably , Maria Luiza M. Barreto-Chaves , Da-Zhi Wang , Gabriela P. Diniz","doi":"10.1016/j.molmet.2024.102065","DOIUrl":"10.1016/j.molmet.2024.102065","url":null,"abstract":"<div><div>Obesity is a major contributor to metabolic and cardiovascular disease. Although senescent cells have been shown to accumulate in adipose tissue, the role of senescence in obesity-induced metabolic disorders and in cardiac dysfunction is not yet clear; therefore, the therapeutic potential of managing senescence in obesity-related metabolic and cardiac disorders remains to be fully defined.</div></div><div><h3>Objective</h3><div>We investigated the beneficial effects of a senolytic cocktail (dasatinib and quercetin) on senescence and its influence on obesity-related parameters.</div></div><div><h3>Methods and Results</h3><div>We found that the increase in body weight and adiposity, glucose intolerance, insulin resistance, dyslipidemia, hyperleptinemia, and hepatic disorders which were induced by an obesogenic diet were alleviated by senolytic cocktail treatment in mice. Treatment with senolytic compounds eliminated senescent cells, counteracting the activation of the senescence program and DNA damage in white adipose tissue (WAT) observed with an obesogenic diet. Moreover, the senolytic cocktail prevented the brown adipose tissue (BAT) whitening and increased the expression of the thermogenic gene profile in BAT and pWAT. In the hearts of obese mice, senolytic combination abolished myocardial maladaptation, reducing the senescence-associated secretory phenotype (SASP) and DNA damage, repressing cardiac hypertrophy, and improving diastolic dysfunction. Additionally, we showed that treatment with the senolytic cocktail corrected gene expression programs associated with fatty acid metabolism, oxidative phosphorylation, the P53 pathway, and DNA repair, which were all downregulated in obese mice.</div></div><div><h3>Conclusions</h3><div>Collectively, these data suggest that a senolytic cocktail can prevent the activation of the senescence program in the heart and WAT and activate the thermogenic program in BAT. Our results suggest that targeting senescent cells may be a novel therapeutic strategy for alleviating obesity-related metabolic and cardiac disorders.</div></div>","PeriodicalId":18765,"journal":{"name":"Molecular Metabolism","volume":"91 ","pages":"Article 102065"},"PeriodicalIF":7.0,"publicationDate":"2024-11-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142667981","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-14DOI: 10.1016/j.molmet.2024.102067
E. Lorza-Gil , O.D. Strauss , E. Ziegler , K. Kansy , M.-T. Katschke , G. Rahimi , D. Neuscheler , L. Sandforth , A. Sandforth , G. Sancar , B. Kaufmann , D. Hartmann , S. Singer , A.L. Mihaljevic , R. Jumpertz-von Schwartzenberg , J. Sbierski-Kind , T.D. Müller , A.L. Birkenfeld , F. Gerst
Objective
Infiltration of adipocytes into the pancreatic parenchyma has been linked to impaired insulin secretion in individuals with increased genetic risk of T2D and prediabetic conditions. However, the study of this ectopic fat depot has been limited by the lack of suitable in vitro models.
Methods
Here, we developed a novel 3D model of functionally mature human pancreatic adipose tissue organoids by aggregating human pancreatic adipose tissue-derived stromal vascular fraction (SVF) cells into organoids and differentiating them over 19 days.
Results
These organoids carry biological properties of the in situ pancreatic fat, presenting levels of adipogenic markers comparable to native pancreatic adipocytes and improved lipolytic and anti-lipolytic response compared to conventional 2D cultures. The organoids harbour a small population of immune cells, mimicking in vivo adipose environment. Furthermore, they express GIPR, allowing investigation of incretin effects in pancreatic fat. In accordance, GIP and the dual GLP1R/GIPR agonist tirzepatide stimulate lipolysis but had distinct effects on the expression of proinflammatory cytokines.
Conclusions
This novel adipose organoid model is a valuable tool to study the metabolic impact of incretin signalling in pancreatic adipose tissue, revealing potential therapeutic targets of incretins beyond islets. The donor-specific metabolic memory of these organoids enables examination of the pancreatic fat-islet crosstalk in a donor-related metabolic context.
{"title":"Incretin-responsive human pancreatic adipose tissue organoids: A functional model for fatty pancreas research","authors":"E. Lorza-Gil , O.D. Strauss , E. Ziegler , K. Kansy , M.-T. Katschke , G. Rahimi , D. Neuscheler , L. Sandforth , A. Sandforth , G. Sancar , B. Kaufmann , D. Hartmann , S. Singer , A.L. Mihaljevic , R. Jumpertz-von Schwartzenberg , J. Sbierski-Kind , T.D. Müller , A.L. Birkenfeld , F. Gerst","doi":"10.1016/j.molmet.2024.102067","DOIUrl":"10.1016/j.molmet.2024.102067","url":null,"abstract":"<div><h3>Objective</h3><div>Infiltration of adipocytes into the pancreatic parenchyma has been linked to impaired insulin secretion in individuals with increased genetic risk of T2D and prediabetic conditions. However, the study of this ectopic fat depot has been limited by the lack of suitable <em>in vitro</em> models.</div></div><div><h3>Methods</h3><div>Here, we developed a novel 3D model of functionally mature human pancreatic adipose tissue organoids by aggregating human pancreatic adipose tissue-derived stromal vascular fraction (SVF) cells into organoids and differentiating them over 19 days.</div></div><div><h3>Results</h3><div>These organoids carry biological properties of the <em>in situ</em> pancreatic fat, presenting levels of adipogenic markers comparable to native pancreatic adipocytes and improved lipolytic and anti-lipolytic response compared to conventional 2D cultures. The organoids harbour a small population of immune cells, mimicking <em>in vivo</em> adipose environment. Furthermore, they express GIPR, allowing investigation of incretin effects in pancreatic fat. In accordance, GIP and the dual GLP1R/GIPR agonist tirzepatide stimulate lipolysis but had distinct effects on the expression of proinflammatory cytokines.</div></div><div><h3>Conclusions</h3><div>This novel adipose organoid model is a valuable tool to study the metabolic impact of incretin signalling in pancreatic adipose tissue, revealing potential therapeutic targets of incretins beyond islets. The donor-specific metabolic memory of these organoids enables examination of the pancreatic fat-islet crosstalk in a donor-related metabolic context.</div></div>","PeriodicalId":18765,"journal":{"name":"Molecular Metabolism","volume":"91 ","pages":"Article 102067"},"PeriodicalIF":7.0,"publicationDate":"2024-11-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142644397","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-13DOI: 10.1016/j.molmet.2024.102063
Abel Oppong , Yat Hei Leung , Anindya Ghosh , Marie-Line Peyot , Marilène Paquet , Carlos Morales , Hugh J. Clarke , Fahd Al-Mulla , Alexandre Boyer , S. R. Murthy Madiraju , Derek Boerboom , Cristian O'Flaherty , Marc Prentki
Objectives
Obesity, diabetes and high-calorie diets are associated with defective sperm function and lowered male fertility. Mature spermatozoa primarily use fructose and glucose, and glucose and glycerol metabolism are important for sperm function. We recently discovered a novel mammalian enzyme, glycerol-3-phosphate (Gro3P) phosphatase (G3PP), and showed that it operates the glycerol shunt by hydrolyzing Gro3P to glycerol, and regulates glucose, lipid and energy metabolism in pancreatic β-cells and liver. We now observed that G3PP expression is the highest in the testis and spermatozoa, and investigated its role in male fertility.
Methods
We examined G3PP expression during spermatogenesis in mouse and assessed male fertility and spermatozoon function in conditional germ cell specific G3PP-KO (cG3PP-KO) mice and tamoxifen-inducible conditional germ cell G3PP-KO (icG3PP-KO) mice. We also determined the structural and metabolic parameters and oxidative stress in the spermatozoa from icG3PP-KO and control mice.
Results
G3PP expression in mouse spermatocytes and spermatids markedly increases during spermatogenesis. Male cG3PP-KO mice, in which germ cell G3PP is deleted from embryonic stage, are infertile due to dysfunctional sperm with reduced motility and capacitation, and elevated spontaneous acrosomal reaction and oxidative stress. However, icG3PP-KO male mice do not have altered fertility, due to the presence of ∼10% normal spermatozoa. icG3PP-KO spermatozoa display significantly reduced functionality and morphological and ultrastructural alterations. The icG3PP-KO spermatozoa show reduced glycerol production, elevated levels of Gro3P and reactive oxygen species (ROS), and oxidative stress that is associated with increased mitochondrial membrane potential.
Conclusions
Germ cell G3PP deletion leads to the generation of spermatozoa that are functionally and structurally abnormal, likely due to the build-up of Gro3P that increases mitochondrial membrane potential, ROS, and oxidative stress and alters spermatozoa function. Overall, the results indicate that G3PP and the glycerol shunt are essential for normal spermatozoa function and male fertility.
{"title":"Essential role of germ cell glycerol-3-phosphate phosphatase for sperm health, oxidative stress control and male fertility in mice","authors":"Abel Oppong , Yat Hei Leung , Anindya Ghosh , Marie-Line Peyot , Marilène Paquet , Carlos Morales , Hugh J. Clarke , Fahd Al-Mulla , Alexandre Boyer , S. R. Murthy Madiraju , Derek Boerboom , Cristian O'Flaherty , Marc Prentki","doi":"10.1016/j.molmet.2024.102063","DOIUrl":"10.1016/j.molmet.2024.102063","url":null,"abstract":"<div><h3>Objectives</h3><div>Obesity, diabetes and high-calorie diets are associated with defective sperm function and lowered male fertility. Mature spermatozoa primarily use fructose and glucose, and glucose and glycerol metabolism are important for sperm function. We recently discovered a novel mammalian enzyme, glycerol-3-phosphate (Gro3P) phosphatase (G3PP), and showed that it operates the glycerol shunt by hydrolyzing Gro3P to glycerol, and regulates glucose, lipid and energy metabolism in pancreatic β-cells and liver. We now observed that G3PP expression is the highest in the testis and spermatozoa, and investigated its role in male fertility.</div></div><div><h3>Methods</h3><div>We examined G3PP expression during spermatogenesis in mouse and assessed male fertility and spermatozoon function in conditional germ cell specific G3PP-KO (cG3PP-KO) mice and tamoxifen-inducible conditional germ cell G3PP-KO (icG3PP-KO) mice. We also determined the structural and metabolic parameters and oxidative stress in the spermatozoa from icG3PP-KO and control mice.</div></div><div><h3>Results</h3><div>G3PP expression in mouse spermatocytes and spermatids markedly increases during spermatogenesis. Male cG3PP-KO mice, in which germ cell G3PP is deleted from embryonic stage, are infertile due to dysfunctional sperm with reduced motility and capacitation, and elevated spontaneous acrosomal reaction and oxidative stress. However, icG3PP-KO male mice do not have altered fertility, due to the presence of ∼10% normal spermatozoa. icG3PP-KO spermatozoa display significantly reduced functionality and morphological and ultrastructural alterations. The icG3PP-KO spermatozoa show reduced glycerol production, elevated levels of Gro3P and reactive oxygen species (ROS), and oxidative stress that is associated with increased mitochondrial membrane potential.</div></div><div><h3>Conclusions</h3><div>Germ cell G3PP deletion leads to the generation of spermatozoa that are functionally and structurally abnormal, likely due to the build-up of Gro3P that increases mitochondrial membrane potential, ROS, and oxidative stress and alters spermatozoa function. Overall, the results indicate that G3PP and the glycerol shunt are essential for normal spermatozoa function and male fertility.</div></div>","PeriodicalId":18765,"journal":{"name":"Molecular Metabolism","volume":"90 ","pages":"Article 102063"},"PeriodicalIF":7.0,"publicationDate":"2024-11-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142624081","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
<div><h3>Objectives</h3><div>Susceptibility to obesity in humans is driven by the intricate interplay of genetic, environmental and behavioural factors. Moreover, the mechanisms linking maternal obesity to infertility remain largely understudied. In this study, we investigated how variable susceptibility to obesity in mice affects ovarian steroidogenesis, with a particular focus on the leptin-mediated dysregulation of Nodal signalling pathway in theca cells (TC).</div></div><div><h3>Methods</h3><div>C56BL/6J (B6) and 129S1/SvlmJ (129) mice, models of maternal obesity (MO), were fed a chow diet (CD) and a high fat diet (HFD) for 16 weeks. To investigate the contrasting effects of leptin on ovarian steroidogenesis, B6 mice pharmacologically treated with leptin for 16 days on CD were used to model hyperleptinemia, while homozygous ob/ob (−/−) mice with genetic leptin deficiency, also on a CD, were used to examine the effects of obesity in the absence of leptin. Following the characterisation of the mouse phenotype, gonadal fat (GON), whole ovaries (WO), ovarian TC and granulosa cell (GC) fractions were collected for mRNA transcription and protein expression analysis. Finally, <em>in vitro</em> treated ovarian explants obtained from B6 mice were used to further elucidate the effects of Nodal on steroidogenesis.</div></div><div><h3>Results</h3><div>The significant gain in body weight (BW) and fat mass (FM) in HFD-fed B6 mice (p < 0.05), was associated with increased mRNA transcription of the adipose tissue expansion genes <em>Polymerase I and transcript release factor</em> (<em>Cavin</em>), <em>Secreted frizzled-related protein 5</em> (<em>Sfrp5</em>) and <em>Mesoderm specific transcript</em> (<em>Mest</em>) in GON (p < 0.05). Furthermore, the HFD-fed B6 mice presented also impaired glucose metabolism and insulin sensitivity (p < 0.05). In contrast, the HFD-fed 129 mice exhibited no changes in BW and FM, maintaining glucose and insulin metabolism. At the ovarian level, decreased protein expression of Steroidogenic Acute Regulatory Protein (StAR) in WO obtained from HFD-fed B6 mice (p = 0.05), was followed by reduced transcription of key steroidogenic genes like <em>Star</em> and <em>Cytochrome P450 17a1</em> (<em>Cyp17a</em>) in TC (p < 0.05). Furthermore, the transcription of <em>Nodal</em> and its receptors was downregulated (p < 0.05), whereas mRNA levels of <em>Suppressor of cytokine signalling 3 (Socs3)</em> and <em>SMAD family member 7 (Smad7)</em> were upregulated in TC obtained from HFD-fed B6 mice (p < 0.05). No changes were seen in the genes regulating steroidogenesis, Nodal signalling, or <em>Socs3</em> and <em>Smad7</em> activity in the ovaries of HFD-fed 129 mice. Importantly, the pharmacological treatment of lean mice with leptin, upregulated the ovarian transcription of <em>Socs3</em> and <em>Smad7</em>, while downregulating <em>Nodal</em> and its receptors (p < 0.05). Finally, <em>in vitro</em> pharmacological inhi
{"title":"Increased susceptibility to diet-induced obesity in female mice impairs ovarian steroidogenesis: The role of elevated leptin signalling on nodal activity inhibition in theca cells","authors":"Karolina Wołodko , Tjaša Šentjurc , Edyta Walewska , Elżbieta Laniecka , Magdalena Jura , António Galvão","doi":"10.1016/j.molmet.2024.102062","DOIUrl":"10.1016/j.molmet.2024.102062","url":null,"abstract":"<div><h3>Objectives</h3><div>Susceptibility to obesity in humans is driven by the intricate interplay of genetic, environmental and behavioural factors. Moreover, the mechanisms linking maternal obesity to infertility remain largely understudied. In this study, we investigated how variable susceptibility to obesity in mice affects ovarian steroidogenesis, with a particular focus on the leptin-mediated dysregulation of Nodal signalling pathway in theca cells (TC).</div></div><div><h3>Methods</h3><div>C56BL/6J (B6) and 129S1/SvlmJ (129) mice, models of maternal obesity (MO), were fed a chow diet (CD) and a high fat diet (HFD) for 16 weeks. To investigate the contrasting effects of leptin on ovarian steroidogenesis, B6 mice pharmacologically treated with leptin for 16 days on CD were used to model hyperleptinemia, while homozygous ob/ob (−/−) mice with genetic leptin deficiency, also on a CD, were used to examine the effects of obesity in the absence of leptin. Following the characterisation of the mouse phenotype, gonadal fat (GON), whole ovaries (WO), ovarian TC and granulosa cell (GC) fractions were collected for mRNA transcription and protein expression analysis. Finally, <em>in vitro</em> treated ovarian explants obtained from B6 mice were used to further elucidate the effects of Nodal on steroidogenesis.</div></div><div><h3>Results</h3><div>The significant gain in body weight (BW) and fat mass (FM) in HFD-fed B6 mice (p < 0.05), was associated with increased mRNA transcription of the adipose tissue expansion genes <em>Polymerase I and transcript release factor</em> (<em>Cavin</em>), <em>Secreted frizzled-related protein 5</em> (<em>Sfrp5</em>) and <em>Mesoderm specific transcript</em> (<em>Mest</em>) in GON (p < 0.05). Furthermore, the HFD-fed B6 mice presented also impaired glucose metabolism and insulin sensitivity (p < 0.05). In contrast, the HFD-fed 129 mice exhibited no changes in BW and FM, maintaining glucose and insulin metabolism. At the ovarian level, decreased protein expression of Steroidogenic Acute Regulatory Protein (StAR) in WO obtained from HFD-fed B6 mice (p = 0.05), was followed by reduced transcription of key steroidogenic genes like <em>Star</em> and <em>Cytochrome P450 17a1</em> (<em>Cyp17a</em>) in TC (p < 0.05). Furthermore, the transcription of <em>Nodal</em> and its receptors was downregulated (p < 0.05), whereas mRNA levels of <em>Suppressor of cytokine signalling 3 (Socs3)</em> and <em>SMAD family member 7 (Smad7)</em> were upregulated in TC obtained from HFD-fed B6 mice (p < 0.05). No changes were seen in the genes regulating steroidogenesis, Nodal signalling, or <em>Socs3</em> and <em>Smad7</em> activity in the ovaries of HFD-fed 129 mice. Importantly, the pharmacological treatment of lean mice with leptin, upregulated the ovarian transcription of <em>Socs3</em> and <em>Smad7</em>, while downregulating <em>Nodal</em> and its receptors (p < 0.05). Finally, <em>in vitro</em> pharmacological inhi","PeriodicalId":18765,"journal":{"name":"Molecular Metabolism","volume":"91 ","pages":"Article 102062"},"PeriodicalIF":7.0,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142624084","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-12DOI: 10.1016/j.molmet.2024.102064
Yuqin Wu , Andrea Y. Chan , Jana Hauke , Okka Htin Aung , Ashish Foollee , Maria Almira S. Cleofe , Helen Stölting , Mei-Ling Han , Katherine J. Jeppe , Christopher K. Barlow , Jürgen G. Okun , Patricia M. Rusu , Adam J. Rose
Objective
The study aimed to investigate the effects of glucagon on metabolic pathways in mouse models of obesity, fatty liver disease, and type 2 diabetes (T2D) to determine the extent and variability of hepatic glucagon resistance in these conditions.
Methods
We investigated glucagon's effects in mouse models of fatty liver disease, obesity, and type 2 diabetes (T2D), including male BKS-db/db, high-fat diet-fed, and western diet-fed C57Bl/6 mice. Glucagon tolerance tests were performed using the selective glucagon receptor agonist acyl-glucagon (IUB288). Blood glucose, serum and liver metabolites include lipids and amino acids were measured. Additionally, liver protein expression related to glucagon signalling and a comprehensive liver metabolomics were performed.
Results
Western diet-fed mice displayed impaired glucagon response, with reduced blood glucose and PKA activation. In contrast, high-fat diet-fed and db/db mice maintained normal glucagon sensitivity, showing significant elevations in blood glucose and phospho-PKA motif protein expression. Acyl-glucagon treatment also lowered liver alanine and histidine levels in high-fat diet-fed mice, but not in western diet-fed mice. Additionally, some amino acids, such as methionine, were increased by acyl-glucagon only in chow diet control mice. Despite normal glucagon sensitivity in PKA signalling, db/db mice had a distinct metabolomic response, with acyl-glucagon significantly altering 90 metabolites in db/+ mice but only 42 in db/db mice, and classic glucagon-regulated metabolites, such as cyclic adenosine monophosphate (cAMP), being less responsive in db/db mice.
Conclusions
The study reveals that hepatic glucagon resistance in obesity and T2D is complex and not uniform across metabolic pathways, underscoring the complexity of glucagon action in these conditions.
{"title":"Variable glucagon metabolic actions in diverse mouse models of obesity and type 2 diabetes","authors":"Yuqin Wu , Andrea Y. Chan , Jana Hauke , Okka Htin Aung , Ashish Foollee , Maria Almira S. Cleofe , Helen Stölting , Mei-Ling Han , Katherine J. Jeppe , Christopher K. Barlow , Jürgen G. Okun , Patricia M. Rusu , Adam J. Rose","doi":"10.1016/j.molmet.2024.102064","DOIUrl":"10.1016/j.molmet.2024.102064","url":null,"abstract":"<div><h3>Objective</h3><div>The study aimed to investigate the effects of glucagon on metabolic pathways in mouse models of obesity, fatty liver disease, and type 2 diabetes (T2D) to determine the extent and variability of hepatic glucagon resistance in these conditions.</div></div><div><h3>Methods</h3><div>We investigated glucagon's effects in mouse models of fatty liver disease, obesity, and type 2 diabetes (T2D), including male BKS-db/db, high-fat diet-fed, and western diet-fed C57Bl/6 mice. Glucagon tolerance tests were performed using the selective glucagon receptor agonist acyl-glucagon (IUB288). Blood glucose, serum and liver metabolites include lipids and amino acids were measured. Additionally, liver protein expression related to glucagon signalling and a comprehensive liver metabolomics were performed.</div></div><div><h3>Results</h3><div>Western diet-fed mice displayed impaired glucagon response, with reduced blood glucose and PKA activation. In contrast, high-fat diet-fed and db/db mice maintained normal glucagon sensitivity, showing significant elevations in blood glucose and phospho-PKA motif protein expression. Acyl-glucagon treatment also lowered liver alanine and histidine levels in high-fat diet-fed mice, but not in western diet-fed mice. Additionally, some amino acids, such as methionine, were increased by acyl-glucagon only in chow diet control mice. Despite normal glucagon sensitivity in PKA signalling, db/db mice had a distinct metabolomic response, with acyl-glucagon significantly altering 90 metabolites in db/+ mice but only 42 in db/db mice, and classic glucagon-regulated metabolites, such as cyclic adenosine monophosphate (cAMP), being less responsive in db/db mice.</div></div><div><h3>Conclusions</h3><div>The study reveals that hepatic glucagon resistance in obesity and T2D is complex and not uniform across metabolic pathways, underscoring the complexity of glucagon action in these conditions.</div></div>","PeriodicalId":18765,"journal":{"name":"Molecular Metabolism","volume":"90 ","pages":"Article 102064"},"PeriodicalIF":7.0,"publicationDate":"2024-11-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142624090","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The early consumption of calorie-rich diet disrupts circadian rhythms and has adverse effects on memory, yet the effects of time-restricted feeding (TRF) and the underlying molecular mechanisms are unknown. Here, we set out to identify the behavioral and molecular circadian rhythms disruptions generated by juvenile obesogenic diet consumption and their restoration by TRF in male mice.
Methods
Metabolic rhythms were measured by indirect calorimetry and memory performances by behavioral tasks. Hippocampal translatome (pS6_TRAP), enrichment and co-regulated gene network analyses were conducted to identify the molecular pathways involved in memory impairments and their restoration by TRF. Differential exon usage analyses, mass spectrometry and pharmacological intervention were used to confirm thyroid hormone signaling involvement.
Results
We show that four weeks of TRF restore the rhythmicity of metabolic parameters and prevents memory impairments in mice fed a high fat-high sucrose (HFS) diet since weaning, independently of body fat levels. Hippocampal translatome and differential exon usage analyses indicate that impaired memory of mice under ad libitum HFS diet is accompanied by reduced thyroid hormone signaling and altered expression of astrocytic genes regulating glutamate neurotransmission. TRF restored the diurnal expression variation of part of these genes and intra-hippocampal infusion of T3, the active form of thyroid hormone, rescues memory performances and astrocytic gene expression of ad libitum HFS diet-fed mice.
Conclusions
Thus, thyroid hormones contribute to the TRF positive effects on both metabolism and memory in mice fed an obesogenic diet, highlighting this nutritional approach as a powerful tool in addressing obesity brain comorbidities and paving the way for further mechanistic studies on hippocampal thyroid signaling.
{"title":"Time-restricted feeding prevents memory impairments induced by obesogenic diet consumption, via hippocampal thyroid hormone signaling","authors":"Jean-Christophe Helbling , Rachel Ginieis , Pierre Mortessagne , Mariano Ruiz-Gayo , Ioannis Bakoyiannis , Eva-Gunnel Ducourneau , Dominique Ciocca , Illona-Marie Bouleté , Alexandre Favereaux , Aurélia Ces , Enrica Montalban , Lucile Capuron , Freddy Jeanneteau , Guillaume Ferreira , Etienne Challet , Marie-Pierre Moisan","doi":"10.1016/j.molmet.2024.102061","DOIUrl":"10.1016/j.molmet.2024.102061","url":null,"abstract":"<div><h3>Objective</h3><div>The early consumption of calorie-rich diet disrupts circadian rhythms and has adverse effects on memory, yet the effects of time-restricted feeding (TRF) and the underlying molecular mechanisms are unknown. Here, we set out to identify the behavioral and molecular circadian rhythms disruptions generated by juvenile obesogenic diet consumption and their restoration by TRF in male mice.</div></div><div><h3>Methods</h3><div>Metabolic rhythms were measured by indirect calorimetry and memory performances by behavioral tasks. Hippocampal translatome (pS6_TRAP), enrichment and co-regulated gene network analyses were conducted to identify the molecular pathways involved in memory impairments and their restoration by TRF. Differential exon usage analyses, mass spectrometry and pharmacological intervention were used to confirm thyroid hormone signaling involvement.</div></div><div><h3>Results</h3><div>We show that four weeks of TRF restore the rhythmicity of metabolic parameters and prevents memory impairments in mice fed a high fat-high sucrose (HFS) diet since weaning, independently of body fat levels. Hippocampal translatome and differential exon usage analyses indicate that impaired memory of mice under <em>ad libitum</em> HFS diet is accompanied by reduced thyroid hormone signaling and altered expression of astrocytic genes regulating glutamate neurotransmission. TRF restored the diurnal expression variation of part of these genes and intra-hippocampal infusion of T3, the active form of thyroid hormone, rescues memory performances and astrocytic gene expression of <em>ad libitum</em> HFS diet-fed mice.</div></div><div><h3>Conclusions</h3><div>Thus, thyroid hormones contribute to the TRF positive effects on both metabolism and memory in mice fed an obesogenic diet, highlighting this nutritional approach as a powerful tool in addressing obesity brain comorbidities and paving the way for further mechanistic studies on hippocampal thyroid signaling.</div></div>","PeriodicalId":18765,"journal":{"name":"Molecular Metabolism","volume":"90 ","pages":"Article 102061"},"PeriodicalIF":7.0,"publicationDate":"2024-11-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142624087","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-05DOI: 10.1016/j.molmet.2024.102052
Justin B. Collier , Hong Soon Kang , Yun-Gil Roh , Chitrangda Srivastava , Sara A. Grimm , Alan K. Jarmusch , Anton M. Jetten
Objectives
Deficiency in the transcription factor (TF) GLI-Similar 3 (GLIS3) in humans and mice leads to the development of polycystic kidney disease (PKD). In this study, we investigate the role of GLIS3 in the regulation of energy metabolism and mitochondrial functions in relation to its role in normal kidney and metabolic reprogramming in PKD pathogenesis.
Methods
Transcriptomics, cistromics, and metabolomics were used to obtain insights into the role of GLIS3 in the regulation of energy homeostasis and mitochondrial metabolism in normal kidney and PKD pathogenesis using GLIS3-deficient mice.
Results
Transcriptome analysis showed that many genes critical for mitochondrial biogenesis, oxidative phosphorylation (OXPHOS), fatty acid oxidation (FAO), and the tricarboxylic acid (TCA) cycle, including Tfam, Tfb1m, Tfb2m, Ppargc1a, Ppargc1b, Atp5j2, Hadha, and Sdha, are significantly suppressed in kidneys from both ubiquitous and tissue-specific Glis3-deficient mice. ChIP-Seq analysis demonstrated that GLIS3 is associated with the regulatory region of many of these genes, indicating that their transcription is directly regulated by GLIS3. Cistrome analyses revealed that GLIS3 binding loci frequently located near those of hepatocyte nuclear factor 1-Beta (HNF1B) and nuclear respiratory factor 1 (NRF1) suggesting GLIS3 regulates transcription of many metabolic and mitochondrial function-related genes in coordination with these TFs. Seahorse analysis and untargeted metabolomics corroborated that mitochondrial OXPHOS utilization is suppressed in GLIS3-deficient kidneys and showed that key metabolites in glycolysis, TCA cycle, and glutamine pathways were altered indicating increased reliance on aerobic glycolysis and glutamine anaplerosis. These features of metabolic reprogramming may contribute to a bioenergetic environment that supports renal cyst formation and progression in Glis3-deficient mice kidneys.
Conclusions
We identify GLIS3 as a novel positive regulator of the transition from aerobic glycolysis to OXPHOS in normal early postnatal kidney development by directly regulating the transcription of mitochondrial metabolic genes. Loss of GLIS3 induces several features of renal cell metabolic reprogramming. Our study identifies GLIS3 as a new participant in an interconnected transcription regulatory network, that includes HNF1B and NRF1, critical in the regulation of mitochondrial-related gene expression and energy metabolism in normal postnatal kidneys and PKD pathogenesis in Glis3-deficient mice.
{"title":"GLIS3: A novel transcriptional regulator of mitochondrial functions and metabolic reprogramming in postnatal kidney and polycystic kidney disease","authors":"Justin B. Collier , Hong Soon Kang , Yun-Gil Roh , Chitrangda Srivastava , Sara A. Grimm , Alan K. Jarmusch , Anton M. Jetten","doi":"10.1016/j.molmet.2024.102052","DOIUrl":"10.1016/j.molmet.2024.102052","url":null,"abstract":"<div><h3><strong>Objectives</strong></h3><div>Deficiency in the transcription factor (TF) GLI-Similar 3 (GLIS3) in humans and mice leads to the development of polycystic kidney disease (PKD). In this study, we investigate the role of GLIS3 in the regulation of energy metabolism and mitochondrial functions in relation to its role in normal kidney and metabolic reprogramming in PKD pathogenesis.</div></div><div><h3>Methods</h3><div>Transcriptomics, cistromics, and metabolomics were used to obtain insights into the role of GLIS3 in the regulation of energy homeostasis and mitochondrial metabolism in normal kidney and PKD pathogenesis using GLIS3-deficient mice.</div></div><div><h3>Results</h3><div>Transcriptome analysis showed that many genes critical for mitochondrial biogenesis, oxidative phosphorylation (OXPHOS), fatty acid oxidation (FAO), and the tricarboxylic acid (TCA) cycle, including <em>Tfam</em>, <em>Tfb1m</em>, <em>Tfb2m</em>, <em>Ppargc1a</em>, <em>Ppargc1b, Atp5j2</em>, <em>Hadha</em>, and <em>Sdha,</em> are significantly suppressed in kidneys from both ubiquitous and tissue-specific <em>Glis3-</em>deficient mice. ChIP-Seq analysis demonstrated that GLIS3 is associated with the regulatory region of many of these genes, indicating that their transcription is directly regulated by GLIS3. Cistrome analyses revealed that GLIS3 binding loci frequently located near those of hepatocyte nuclear factor 1-Beta (HNF1B) and nuclear respiratory factor 1 (NRF1) suggesting GLIS3 regulates transcription of many metabolic and mitochondrial function-related genes in coordination with these TFs. Seahorse analysis and untargeted metabolomics corroborated that mitochondrial OXPHOS utilization is suppressed in GLIS3-deficient kidneys and showed that key metabolites in glycolysis, TCA cycle, and glutamine pathways were altered indicating increased reliance on aerobic glycolysis and glutamine anaplerosis. These features of metabolic reprogramming may contribute to a bioenergetic environment that supports renal cyst formation and progression in <em>Glis3</em>-deficient mice kidneys.</div></div><div><h3>Conclusions</h3><div>We identify GLIS3 as a novel positive regulator of the transition from aerobic glycolysis to OXPHOS in normal early postnatal kidney development by directly regulating the transcription of mitochondrial metabolic genes. Loss of GLIS3 induces several features of renal cell metabolic reprogramming. Our study identifies GLIS3 as a new participant in an interconnected transcription regulatory network, that includes HNF1B and NRF1, critical in the regulation of mitochondrial-related gene expression and energy metabolism in normal postnatal kidneys and PKD pathogenesis in <em>Glis3</em>-deficient mice.</div></div>","PeriodicalId":18765,"journal":{"name":"Molecular Metabolism","volume":"90 ","pages":"Article 102052"},"PeriodicalIF":7.0,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142591348","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2024-11-01DOI: 10.1016/j.molmet.2024.102056
Neil V. Yang , Justin Y. Chao , Kelly A. Garton , Tommy Tran , Sarah M. King , Joseph Orr , Jacob H. Oei , Alexandra Crawford , Misun Kang , Reena Zalpuri , Danielle M. Jorgens , Pranav Konchadi , John S. Chorba , Elizabeth Theusch , Ronald M. Krauss
Objective
The gene encoding TOMM40 (Transporter of Outer Mitochondrial Membrane 40) is adjacent to that encoding APOE, which has a central role in lipid and lipoprotein metabolism. While human genetic variants near APOE and TOMM40 have been shown to be strongly associated with plasma lipid levels, a specific role for TOMM40 in lipid metabolism has not been established, and the present study was aimed at assessing this possibility.
Methods
TOMM40 was knocked down by siRNA in human hepatoma HepG2 cells, and effects on mitochondrial function, lipid phenotypes, and crosstalk between mitochondria, ER, and lipid droplets were examined. Additionally, hepatic and plasma lipid levels were measured in mice following shRNA-induced knockdown of Tomm40 shRNA.
Results
In HepG2 cells, TOMM40 knockdown upregulated expression of APOE and LDLR in part via activation of LXRB (NR1H2) by oxysterols, with consequent increased uptake of VLDL and LDL. This is in part due to disruption of mitochondria-endoplasmic reticulum contact sites, with resulting accrual of reactive oxygen species and non-enzymatically derived oxysterols. With TOMM40 knockdown, cellular triglyceride and lipid droplet content were increased, effects attributable in part to receptor-mediated VLDL uptake, since lipid staining was significantly reduced by concomitant suppression of either LDLR or APOE. In contrast, cellular cholesterol content was reduced due to LXRB-mediated upregulation of the ABCA1 transporter as well as increased production and secretion of oxysterol-derived cholic acid. Consistent with the findings in hepatoma cells, in vivo knockdown of TOMM40 in mice resulted in significant reductions of plasma triglyceride and cholesterol concentrations, reduced hepatic cholesterol and increased triglyceride content, and accumulation of lipid droplets leading to development of steatosis.
Conclusions
These findings demonstrate a role for TOMM40 in regulating hepatic lipid and plasma lipoprotein levels and identify mechanisms linking mitochondrial function with lipid metabolism.
{"title":"TOMM40 regulates hepatocellular and plasma lipid metabolism via an LXR-dependent pathway","authors":"Neil V. Yang , Justin Y. Chao , Kelly A. Garton , Tommy Tran , Sarah M. King , Joseph Orr , Jacob H. Oei , Alexandra Crawford , Misun Kang , Reena Zalpuri , Danielle M. Jorgens , Pranav Konchadi , John S. Chorba , Elizabeth Theusch , Ronald M. Krauss","doi":"10.1016/j.molmet.2024.102056","DOIUrl":"10.1016/j.molmet.2024.102056","url":null,"abstract":"<div><h3>Objective</h3><div>The gene encoding TOMM40 (Transporter of Outer Mitochondrial Membrane 40) is adjacent to that encoding APOE, which has a central role in lipid and lipoprotein metabolism. While human genetic variants near <em>APOE</em> and <em>TOMM40</em> have been shown to be strongly associated with plasma lipid levels, a specific role for TOMM40 in lipid metabolism has not been established, and the present study was aimed at assessing this possibility.</div></div><div><h3>Methods</h3><div><em>TOMM40</em> was knocked down by siRNA in human hepatoma HepG2 cells, and effects on mitochondrial function, lipid phenotypes, and crosstalk between mitochondria, ER, and lipid droplets were examined. Additionally, hepatic and plasma lipid levels were measured in mice following shRNA-induced knockdown of <em>Tomm40</em> shRNA.</div></div><div><h3>Results</h3><div>In HepG2 cells, <em>TOMM40</em> knockdown upregulated expression of <em>APOE</em> and <em>LDLR</em> in part via activation of LXRB (NR1H2) by oxysterols, with consequent increased uptake of VLDL and LDL. This is in part due to disruption of mitochondria-endoplasmic reticulum contact sites, with resulting accrual of reactive oxygen species and non-enzymatically derived oxysterols. With <em>TOMM40</em> knockdown, cellular triglyceride and lipid droplet content were increased, effects attributable in part to receptor-mediated VLDL uptake, since lipid staining was significantly reduced by concomitant suppression of either <em>LDLR</em> or <em>APOE</em>. In contrast, cellular cholesterol content was reduced due to LXRB-mediated upregulation of the ABCA1 transporter as well as increased production and secretion of oxysterol-derived cholic acid. Consistent with the findings in hepatoma cells, <em>in vivo</em> knockdown of <em>TOMM40</em> in mice resulted in significant reductions of plasma triglyceride and cholesterol concentrations, reduced hepatic cholesterol and increased triglyceride content, and accumulation of lipid droplets leading to development of steatosis.</div></div><div><h3>Conclusions</h3><div>These findings demonstrate a role for TOMM40 in regulating hepatic lipid and plasma lipoprotein levels and identify mechanisms linking mitochondrial function with lipid metabolism.</div></div>","PeriodicalId":18765,"journal":{"name":"Molecular Metabolism","volume":"90 ","pages":"Article 102056"},"PeriodicalIF":7.0,"publicationDate":"2024-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142568636","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}