Life metabolismPub Date : 2023-04-01Epub Date: 2023-04-04DOI: 10.1093/lifemeta/load014
Patrick J Ferrara, Marisa J Lang, Jordan M Johnson, Shinya Watanabe, Kelsey L McLaughlin, J Alan Maschek, Anthony R P Verkerke, Piyarat Siripoksup, Amandine Chaix, James E Cox, Kelsey H Fisher-Wellman, Katsuhiko Funai
{"title":"Weight loss increases skeletal muscle mitochondrial energy efficiency in obese mice.","authors":"Patrick J Ferrara, Marisa J Lang, Jordan M Johnson, Shinya Watanabe, Kelsey L McLaughlin, J Alan Maschek, Anthony R P Verkerke, Piyarat Siripoksup, Amandine Chaix, James E Cox, Kelsey H Fisher-Wellman, Katsuhiko Funai","doi":"10.1093/lifemeta/load014","DOIUrl":"10.1093/lifemeta/load014","url":null,"abstract":"<p><p>Weight loss from an overweight state is associated with a disproportionate decrease in whole-body energy expenditure that may contribute to the heightened risk for weight regain. Evidence suggests that this energetic mismatch originates from lean tissue. Although this phenomenon is well documented, the mechanisms have remained elusive. We hypothesized that increased mitochondrial energy efficiency in skeletal muscle is associated with reduced expenditure under weight loss. Wildtype (WT) male C57BL6/N mice were fed with high fat diet for 10 weeks, followed by a subset of mice that were maintained on the obesogenic diet (OB) or switched to standard chow to promote weight loss (WL) for additional 6 weeks. Mitochondrial energy efficiency was evaluated using high-resolution respirometry and fluorometry. Mass spectrometric analyses were employed to describe the mitochondrial proteome and lipidome. Weight loss promoted ~50% increase in the efficiency of oxidative phosphorylation (ATP produced per O<sub>2</sub> consumed, or P/O) in skeletal muscle. However, weight loss did not appear to induce significant changes in mitochondrial proteome, nor any changes in respiratory supercomplex formation. Instead, it accelerated the remodeling of mitochondrial cardiolipin (CL) acyl-chains to increase tetralinoleoyl CL (TLCL) content, a species of lipids thought to be functionally critical for the respiratory enzymes. We further show that lowering TLCL by deleting the CL transacylase tafazzin was sufficient to reduce skeletal muscle P/O and protect mice from diet-induced weight gain. These findings implicate skeletal muscle mitochondrial efficiency as a novel mechanism by which weight loss reduces energy expenditure in obesity.</p>","PeriodicalId":74074,"journal":{"name":"Life metabolism","volume":"2 2","pages":""},"PeriodicalIF":0.0,"publicationDate":"2023-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10195096/pdf/nihms-1890467.pdf","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"9770381","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Life metabolismPub Date : 2023-03-23eCollection Date: 2023-04-01DOI: 10.1093/lifemeta/load010
Tiantian Ma, Wei Mao, Shaohua Zhang, Yaqing Wang, Tao Wang, Jinghua Liu, Lei Shi, Xiang Yu, Rong Xue, Guanghou Shui, Zhiheng Xu
{"title":"Ablation of <i>Mea6/cTAGE5</i> in oligodendrocytes significantly impairs white matter structure and lipid content.","authors":"Tiantian Ma, Wei Mao, Shaohua Zhang, Yaqing Wang, Tao Wang, Jinghua Liu, Lei Shi, Xiang Yu, Rong Xue, Guanghou Shui, Zhiheng Xu","doi":"10.1093/lifemeta/load010","DOIUrl":"10.1093/lifemeta/load010","url":null,"abstract":"<p><p>Lipid-rich myelin is a special structure formed by oligodendrocytes wrapping neuronal axons. Abnormal myelin sheath is associated with many neurological diseases. Meningioma-expressed antigen 6 (Mea6)/cutaneous T cell lymphoma-associated antigen 5C (cTAGE5C) plays an important role in vesicle trafficking from the endoplasmic reticulum (ER) to Golgi, and conditional knockout (cKO) of <i>Mea6</i> in the brain significantly affects neural development and brain function. However, whether the impaired brain function involves the development of oligodendrocytes and white matter beyond neurons remains unclear. In this study, by using different models of diffusion magnetic resonance imaging, we showed that cKO of <i>Mea6</i> in oligodendrocytes leads to significant impairment of the gross and microstructure of the white matter, as well as a significant decrease of cholesterol and triglycerides in brains. Our lipidomic analysis of purified myelin sheath for the first time showed that <i>Mea6</i> elimination in oligodendrocytes significantly altered the lipid composition in myelin lipidome, especially the proportion of very long chain fatty acids (VLCFAs). In particular, the levels of most VLCFA-containing phosphatidylcholines were substantially lower in the myelin sheath of the cKO mice. The reduction of VLCFAs is likely due to the downregulated expression of <i>elongation of very long chain fatty acids</i> (<i>ELOVLs</i>). Our study of an animal model with white matter malformation and the comprehensive lipid profiling would provide clues for future studies of the formation of myelin sheath, myelin lipids, and the pathogenesis of white matter diseases.</p>","PeriodicalId":74074,"journal":{"name":"Life metabolism","volume":" ","pages":"load010"},"PeriodicalIF":0.0,"publicationDate":"2023-03-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11748983/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48676341","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Fluorescent visualization and evaluation of NPC1L1-mediated vesicular endocytosis during intestinal cholesterol absorption in mice.","authors":"Xiaojing Wu, Xian-Hua Ma, Jie Lin, Xiaohang Yang, Jian-Hui Shi, Zhifang Xie, Yu-Xia Chen, Weiping J Zhang","doi":"10.1093/lifemeta/load011","DOIUrl":"10.1093/lifemeta/load011","url":null,"abstract":"<p><p>Excessive cholesterol absorption from intestinal lumen contributes to the pathogenesis of hypercholesterolemia, which is an independent risk factor for atherosclerotic cardiovascular disease. Niemann-Pick C1-like 1 (NPC1L1) is a major membrane protein responsible for cholesterol absorption, in which the physiological role of vesicular endocytosis is still controversial, and it lacks a feasible tool to visualize and evaluate the endocytosis of NPC1L1 vesicles <i>in vivo</i>. Here, we genetically labeled endogenous NPC1L1 protein with EGFP in a knock-in mouse model, and demonstrated fluorescent visualization and evaluation of the endocytic vesicles of NPC1L1-cago during intestinal cholesterol absorption. The homozygous NPC1L1-EGFP mice have normal NPC1L1 expression pattern as well as cholesterol homeostasis on chow or high-cholesterol diets. The fluorescence of NPC1L1-EGFP fusion protein localizes at the brush border membrane of small intestine, and EGFP-positive vesicles is visualized beneath the membrane as early as 5 min post oral gavage of cholesterol. Of note, the vesicles colocalize with the early endosomal marker early endosome antigen 1 (EEA1) and the filipin-stained free cholesterol. Pretreatment with NPC1L1 inhibitor ezetimibe inhibits the formation of these cholesterol-induced endocytic vesicles. Our data support the notion that NPC1L1-mediated cholesterol absorption is a vesicular endocytic process. NPC1L1-EGFP mice are a useful model for visualizing cellular NPC1L1-cargo vesicle itineraries and for evaluating NPC1L1 activity <i>in vivo</i> in response to diverse pharmacological agents and nutrients.</p>","PeriodicalId":74074,"journal":{"name":"Life metabolism","volume":" ","pages":"load011"},"PeriodicalIF":0.0,"publicationDate":"2023-03-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11749127/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48339678","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Hierarchical inhibition of mTORC1 by glucose starvation-triggered AXIN lysosomal translocation and by AMPK.","authors":"Mengqi Li, Xiaoyan Wei, Jinye Xiong, Jin-Wei Feng, Chen-Song Zhang, Sheng-Cai Lin","doi":"10.1093/lifemeta/load005","DOIUrl":"10.1093/lifemeta/load005","url":null,"abstract":"<p><p>When glucose is replete, mammalian/mechanistic target of rapamycin complex 1 (mTORC1) is active and anchored to the lysosomal surface via the two GTPases, Ras-related GTPase (RAG) and Ras homolog enriched in brain (Rheb), which are regulated by Ragulator and tuberous sclerosis complex 2 (TSC2), respectively. When glucose is low, aldolase senses low fructose-1,6-bisphosphate level and promotes the translocation of AXIN-liver kinase B1 (LKB1) to the lysosomal surface, which leads to the activation of AMP-activated protein kinase (AMPK) and the inhibition of RAGs, sundering mTORC1 from the lysosome and causing its inactivation. AMPK can also inactivate mTORC1 by phosphorylating Raptor and TSC2. However, the hierarchy of AXIN- and AMPK-mediated inhibition of mTORC1 remains poorly defined. Here, we show that AXIN translocation does not require AMPK expression or activity. In glucose starvation conditions, knockout of AXIN extended the half-life of mTORC1 inhibition from 15 to 60 min, whereas knockout of AMPK only extended it to 30 min. RAGB<sup>GTP</sup> (constitutively active RAGB) almost entirely blocked the lysosomal dissociation and inhibition of mTORC1 under glucose starvation, but it did not inhibit AMPK, indicating that under these conditions, it is AXIN lysosomal translocation that inhibits mTORC1, and it does so via inhibition of RAGs. 5-aminoimidazole-4-carboxamide ribonucleoside (AICAR), a mimetic of AMP, which activates both cytosolic AMPK and lysosomal AMPK, fully inhibited mTORC1 even when it is stably anchored to the lysosome by RAGB<sup>GTP</sup>, whereas glucose starvation mildly inhibited such anchored mTORC1. Together, we demonstrate that the lysosomal translocation of AXIN plays a primary role in glucose starvation-triggered inhibition of mTORC1 by inhibiting RAGs, and that AMPK activity inhibits mTORC1 through phosphorylating Raptor and TSC2, especially under severe stress.</p>","PeriodicalId":74074,"journal":{"name":"Life metabolism","volume":"38 2","pages":"load005"},"PeriodicalIF":0.0,"publicationDate":"2023-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11749110/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"41295836","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Life metabolismPub Date : 2023-02-21eCollection Date: 2023-02-01DOI: 10.1093/lifemeta/load007
Xuelian Xiong, Xiaoying Li
{"title":"Type 2 diabetes originated from non-alcoholic fatty liver disease.","authors":"Xuelian Xiong, Xiaoying Li","doi":"10.1093/lifemeta/load007","DOIUrl":"10.1093/lifemeta/load007","url":null,"abstract":"<p><p>Both non-alcoholic fatty liver disease (NAFLD) and type 2 diabetes mellitus (T2DM) are highly prevalent metabolic liver diseases. Accumulating epidemiological evidence now indicates that NAFLD and T2DM are strongly associated, yet the causative relationship remains to be elucidated. Liver serves as a hub for nutrient and energy metabolism in the body. Here we demonstrated the pathogenesis linking NAFLD to T2DM through a series of studies and the attenuation of T2DM progression after NALFD improvement in cohort study. We proposed the urgent necessity of NAFLD management and NAFLD drug development, which might be novel therapeutic avenues for T2DM.</p>","PeriodicalId":74074,"journal":{"name":"Life metabolism","volume":" ","pages":"load007"},"PeriodicalIF":0.0,"publicationDate":"2023-02-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11749538/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48594877","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Life metabolismPub Date : 2023-02-08eCollection Date: 2023-02-01DOI: 10.1093/lifemeta/load006
Jessie C Morrill, Qingchun Tong
{"title":"You are what you eat: feeding neurons in nutrient regulation of behavior.","authors":"Jessie C Morrill, Qingchun Tong","doi":"10.1093/lifemeta/load006","DOIUrl":"10.1093/lifemeta/load006","url":null,"abstract":"","PeriodicalId":74074,"journal":{"name":"Life metabolism","volume":" ","pages":"load006"},"PeriodicalIF":0.0,"publicationDate":"2023-02-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11749734/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47715770","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Leucine deprivation results in antidepressant effects via GCN2 in AgRP neurons.","authors":"Feixiang Yuan, Shangming Wu, Ziheng Zhou, Fuxin Jiao, Hanrui Yin, Yuguo Niu, Haizhou Jiang, Shanghai Chen, Feifan Guo","doi":"10.1093/lifemeta/load004","DOIUrl":"10.1093/lifemeta/load004","url":null,"abstract":"<p><p>Essential amino acids (EAAs) are crucial nutrients, whose levels change in rodents and patients with depression. However, how the levels of a single EAA affects depressive behaviors remains elusive. Here, we demonstrate that although deprivation of the EAA leucine has no effect in unstressed mice, it remarkably reverses the depression-like behaviors induced by chronic restraint stress (CRS). This beneficial effect is independent of feeding and is applicable to the dietary deficiency of other EAAs. Furthermore, the effect of leucine deprivation is suppressed by central injection of leucine or mimicked by central injection of leucinol. Moreover, hypothalamic agouti-related peptide (AgRP) neural activity changes during CRS and leucine deprivation, and chemogenetically inhibiting AgRP neurons eliminates the antidepressant effects of leucine deprivation. Finally, the leucine deprivation-regulated behavioral effects are mediated by amino acid sensor general control non-derepressible 2 (GCN2) in AgRP neurons. Taken together, our results suggest a new drug target and/or dietary intervention for the reduction of depressive symptoms.</p>","PeriodicalId":74074,"journal":{"name":"Life metabolism","volume":" ","pages":"load004"},"PeriodicalIF":0.0,"publicationDate":"2023-02-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11748975/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"47134845","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}