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Agostini F, Pereyra L, Dale J, Yambire KF, Maglioni S, Schiavi A, Ventura N, Milosevic I, Raimundo N. Upregulation of cholesterol synthesis by lysosomal defects requires a functional mitochondrial respiratory chain. J Biol Chem 2024; 300:107403. [PMID: 38782205 PMCID: PMC11254723 DOI: 10.1016/j.jbc.2024.107403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Revised: 04/27/2024] [Accepted: 05/03/2024] [Indexed: 05/25/2024] Open
Abstract
Mitochondria and lysosomes are two organelles that carry out both signaling and metabolic roles in cells. Recent evidence has shown that mitochondria and lysosomes are dependent on one another, as primary defects in one cause secondary defects in the other. Although there are functional impairments in both cases, the signaling consequences of primary mitochondrial dysfunction and lysosomal defects are dissimilar. Here, we used RNA sequencing to obtain transcriptomes from cells with primary mitochondrial or lysosomal defects to identify the global cellular consequences associated with mitochondrial or lysosomal dysfunction. We used these data to determine the pathways affected by defects in both organelles, which revealed a prominent role for the cholesterol synthesis pathway. We observed a transcriptional upregulation of this pathway in cellular and murine models of lysosomal defects, while it is transcriptionally downregulated in cellular and murine models of mitochondrial defects. We identified a role for the posttranscriptional regulation of transcription factor SREBF1, a master regulator of cholesterol and lipid biosynthesis, in models of mitochondrial respiratory chain deficiency. Furthermore, we found that retention of Ca2+ in lysosomes of cells with mitochondrial respiratory chain defects contributes to the differential regulation of the cholesterol synthesis pathway in the mitochondrial and lysosomal defects tested. Finally, we verified in vivo, using a model of mitochondria-associated disease in Caenorhabditis elegans that normalization of lysosomal Ca2+ levels results in partial rescue of the developmental delay induced by the respiratory chain deficiency.
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Affiliation(s)
- Francesco Agostini
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, Pennsylvania, USA
| | - Leonardo Pereyra
- Department of Cellular Biochemistry, University Medical Center, Goettingen, Germany
| | - Justin Dale
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, Pennsylvania, USA
| | - King Faisal Yambire
- Laboratory of Systems Cancer Biology, The Rockefeller University, New York, New York, USA
| | - Silvia Maglioni
- IUF-Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany; Institute for Clinical Chemistry and Laboratory Diagnostic, Medical Faculty, Heinrich Heine University, Duesseldorf, Germany
| | - Alfonso Schiavi
- IUF-Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany
| | - Natascia Ventura
- IUF-Leibniz Research Institute for Environmental Medicine, Duesseldorf, Germany; Institute for Clinical Chemistry and Laboratory Diagnostic, Medical Faculty, Heinrich Heine University, Duesseldorf, Germany
| | - Ira Milosevic
- Centre for Human Genetics, Nuffield Department of Medicine, University of Oxford, Oxford, UK; Multidisciplinary Institute for Ageing, University of Coimbra, Coimbra, Portugal
| | - Nuno Raimundo
- Department of Cellular and Molecular Physiology, Penn State College of Medicine, Hershey, Pennsylvania, USA; Penn State Cancer Institute, Penn State College of Medicine, Hershey, Pennsylvania, USA.
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Agostini F, Pereyra L, Dale J, Yambire KF, Maglioni S, Schiavi A, Ventura N, Milosevic I, Raimundo N. Up-regulation of cholesterol synthesis by lysosomal defects requires a functional mitochondrial respiratory chain. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2024:2024.03.06.583589. [PMID: 38496624 PMCID: PMC10942416 DOI: 10.1101/2024.03.06.583589] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2024]
Abstract
Mitochondria and lysosomes are two organelles that carry out both signaling and metabolic roles in the cells. Recent evidence has shown that mitochondria and lysosomes are dependent on one another, as primary defects in one cause secondary defects in the other. Nevertheless, the signaling consequences of primary mitochondrial malfunction and of primary lysosomal defects are not similar, despite in both cases there are impairments of mitochondria and of lysosomes. Here, we used RNA sequencing to obtain transcriptomes from cells with primary mitochondrial or lysosomal defects, to identify what are the global cellular consequences that are associated with malfunction of mitochondria or lysosomes. We used these data to determine what are the pathways that are affected by defects in both organelles, which revealed a prominent role for the cholesterol synthesis pathway. This pathway is transcriptionally up-regulated in cellular and mouse models of lysosomal defects and is transcriptionally down-regulated in cellular and mouse models of mitochondrial defects. We identified a role for post-transcriptional regulation of the transcription factor SREBF1, a master regulator of cholesterol and lipid biosynthesis, in models of mitochondrial respiratory chain deficiency. Furthermore, the retention of Ca 2+ in the lysosomes of cells with mitochondrial respiratory chain defects contributes to the differential regulation of the cholesterol synthesis pathway in the mitochondrial and lysosomal defects tested. Finally, we verified in vivo , using models of mitochondria-associated diseases in C. elegans , that normalization of lysosomal Ca 2+ levels results in partial rescue of the developmental arrest induced by the respiratory chain deficiency.
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Lee DK, Jo SH, Lee ES, Ha KB, Park NW, Kong DH, Park SI, Park JS, Chung CH. DWN12088, A Prolyl-tRNA Synthetase Inhibitor, Alleviates Hepatic Injury in Nonalcoholic Steatohepatitis. Diabetes Metab J 2024; 48:97-111. [PMID: 38173372 PMCID: PMC10850270 DOI: 10.4093/dmj.2022.0367] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2022] [Accepted: 03/22/2023] [Indexed: 01/05/2024] Open
Abstract
BACKGRUOUND Nonalcoholic steatohepatitis (NASH) is a liver disease caused by obesity that leads to hepatic lipoapoptosis, resulting in fibrosis and cirrhosis. However, the mechanism underlying NASH is largely unknown, and there is currently no effective therapeutic agent against it. DWN12088, an agent used for treating idiopathic pulmonary fibrosis, is a selective prolyl-tRNA synthetase (PRS) inhibitor that suppresses the synthesis of collagen. However, the mechanism underlying the hepatoprotective effect of DWN12088 is not clear. Therefore, we investigated the role of DWN12088 in NASH progression. METHODS Mice were fed a chow diet or methionine-choline deficient (MCD)-diet, which was administered with DWN12088 or saline by oral gavage for 6 weeks. The effects of DWN12088 on NASH were evaluated by pathophysiological examinations, such as real-time quantitative reverse transcription polymerase chain reaction, immunoblotting, biochemical analysis, and immunohistochemistry. Molecular and cellular mechanisms of hepatic injury were assessed by in vitro cell culture. RESULTS DWN12088 attenuated palmitic acid (PA)-induced lipid accumulation and lipoapoptosis by downregulating the Rho-kinase (ROCK)/AMP-activated protein kinase (AMPK)/sterol regulatory element-binding protein-1c (SREBP-1c) and protein kinase R-like endoplasmic reticulum kinase (PERK)/α subunit of eukaryotic initiation factor 2 (eIF2α)/activating transcription factor 4 (ATF4)/C/EBP-homologous protein (CHOP) signaling cascades. PA increased but DWN12088 inhibited the phosphorylation of nuclear factor-κB (NF-κB) p65 (Ser536, Ser276) and the expression of proinflammatory genes. Moreover, the DWN12088 inhibited transforming growth factor β (TGFβ)-induced pro-fibrotic gene expression by suppressing TGFβ receptor 1 (TGFβR1)/Smad2/3 and TGFβR1/glutamyl-prolyl-tRNA synthetase (EPRS)/signal transducer and activator of transcription 6 (STAT6) axis signaling. In the case of MCD-diet-induced NASH, DWN12088 reduced hepatic steatosis, inflammation, and lipoapoptosis and prevented the progression of fibrosis. CONCLUSION Our findings provide new insights about DWN12088, namely that it plays an important role in the overall improvement of NASH. Hence, DWN12088 shows great potential to be developed as a new integrated therapeutic agent for NASH.
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Affiliation(s)
- Dong-Keon Lee
- Department of Internal Medicine and Research Institute of Metabolism and Inflammation, Yonsei University Wonju College of Medicine, Wonju, Korea
- Division of Research Program, Scripps Korea Antibody Institute, Chuncheon, Korea
| | - Su Ho Jo
- Department of Internal Medicine and Research Institute of Metabolism and Inflammation, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - Eun Soo Lee
- Department of Internal Medicine and Research Institute of Metabolism and Inflammation, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - Kyung Bong Ha
- Department of Internal Medicine and Research Institute of Metabolism and Inflammation, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - Na Won Park
- Department of Internal Medicine and Research Institute of Metabolism and Inflammation, Yonsei University Wonju College of Medicine, Wonju, Korea
| | - Deok-Hoon Kong
- Division of Research Program, Scripps Korea Antibody Institute, Chuncheon, Korea
| | - Sang-In Park
- Division of Research Program, Scripps Korea Antibody Institute, Chuncheon, Korea
| | - Joon Seok Park
- Drug Discovery Center, Daewoong Pharmaceutical Co. Ltd., Seoul, Korea
| | - Choon Hee Chung
- Department of Internal Medicine and Research Institute of Metabolism and Inflammation, Yonsei University Wonju College of Medicine, Wonju, Korea
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Liu H, Sun Y, Zhang X, Li S, Hu D, Xiao L, Chen Y, He L, Wang DW. Integrated Analysis of Summary Statistics to Identify Pleiotropic Genes and Pathways for the Comorbidity of Schizophrenia and Cardiometabolic Disease. Front Psychiatry 2020; 11:256. [PMID: 32425817 PMCID: PMC7212438 DOI: 10.3389/fpsyt.2020.00256] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2019] [Accepted: 03/17/2020] [Indexed: 12/31/2022] Open
Abstract
Genome-wide association studies (GWAS) have identified abundant risk loci associated with schizophrenia (SCZ), cardiometabolic disease (CMD) including body mass index, coronary artery diseases, type 2 diabetes, low- and high-density lipoprotein, total cholesterol, and triglycerides. Although recent studies have suggested that genetic risk shared between these disorders, the pleiotropic genes and biological pathways shared between them are still vague. Here we integrated comprehensive multi-dimensional data from GWAS, expression quantitative trait loci (eQTL), and gene set database to systematically identify potential pleiotropic genes and biological pathways shared between SCZ and CMD. By integrating the results from different approaches including FUMA, Sherlock, SMR, UTMOST, FOCUS, and DEPICT, we revealed 21 pleiotropic genes that are likely to be shared between SCZ and CMD. These genes include VRK2, SLC39A8, NT5C2, AMBRA1, ARL6IP4, OGFOD2, PITPNM2, CDK2AP1, C12orf65, ABCB9, SETD8, MPHOSPH9, FES, FURIN, INO80E, YPEL3, MAPK3, SREBF1, TOM1L2, GATAD2A, and TM6SF2. In addition, we also performed the gene-set enrichment analysis using the software of GSA-SNP2 and MAGMA with GWAS summary statistics and identified three biological pathways (MAPK-TRK signaling, growth hormone signaling, and regulation of insulin secretion signaling) shared between them. Our study provides insights into the pleiotropic genes and biological pathways underlying mechanisms for the comorbidity of SCZ and CMD. However, further genetic and functional studies are required to validate the role of these potential pleiotropic genes and pathways in the etiology of the comorbidity of SCZ and CMD, which should provide potential targets for future diagnostics and therapeutics.
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Affiliation(s)
- Hao Liu
- Division of Cardiology, Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Hubei Key Laboratory of Genetics and Molecular Mechanisms of Cardiological Disorders, Wuhan, China
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Collaborative Innovation Center for Genetics and Development, Shanghai Mental Health Center, Shanghai Jiaotong University, Shanghai, China
| | - Yang Sun
- Division of Cardiology, Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Hubei Key Laboratory of Genetics and Molecular Mechanisms of Cardiological Disorders, Wuhan, China
| | - Xinxin Zhang
- Division of Cardiology, Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Collaborative Innovation Center for Genetics and Development, Shanghai Mental Health Center, Shanghai Jiaotong University, Shanghai, China
| | - Shiyang Li
- Division of Cardiology, Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Hubei Key Laboratory of Genetics and Molecular Mechanisms of Cardiological Disorders, Wuhan, China
| | - Dong Hu
- Division of Cardiology, Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Hubei Key Laboratory of Genetics and Molecular Mechanisms of Cardiological Disorders, Wuhan, China
| | - Lei Xiao
- Division of Cardiology, Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Hubei Key Laboratory of Genetics and Molecular Mechanisms of Cardiological Disorders, Wuhan, China
| | - Yanghui Chen
- Division of Cardiology, Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Hubei Key Laboratory of Genetics and Molecular Mechanisms of Cardiological Disorders, Wuhan, China
| | - Lin He
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Collaborative Innovation Center for Genetics and Development, Shanghai Mental Health Center, Shanghai Jiaotong University, Shanghai, China
| | - Dao Wen Wang
- Division of Cardiology, Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
- Hubei Key Laboratory of Genetics and Molecular Mechanisms of Cardiological Disorders, Wuhan, China
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Ferreira MDR, Oliva ME, Aiassa V, D'Alessandro ME. Salvia hispanica L. (chia) seed improves skeletal muscle lipotoxicity and insulin sensitivity in rats fed a sucrose-rich diet by modulating intramuscular lipid metabolism. J Funct Foods 2020. [DOI: 10.1016/j.jff.2019.103775] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
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Xu F, Cao H, Chen Z, Gu H, Guo W, Lin B, Weng J. Short-term GLP-1 receptor agonist exenatide ameliorates intramyocellular lipid deposition without weight loss in ob/ob mice. Int J Obes (Lond) 2020; 44:937-947. [PMID: 31911662 DOI: 10.1038/s41366-019-0513-y] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2019] [Revised: 11/07/2019] [Accepted: 12/11/2019] [Indexed: 12/15/2022]
Abstract
OBJECTIVE Ectopic lipid deposition is closely associated with type 2 diabetes (T2D). Accumulating evidence shows that GLP-1 receptor agonists (GLP-1 RAs) improve obesity and liver steatosis. However, it remains unknown whether and how they ameliorate lipid deposition in skeletal muscle. This study aimed to investigate the effect of exenatide (a GLP-1 RA) on intramyocellular lipid deposition in the skeletal muscle of T2D models and its dependence on weight loss. METHODS Ob/ob mice and diet-induced obese (DIO) mice were treated with exenatide (24 nmol/kg), leptin (1 mg/kg), or saline control intraperitoneally once daily for 4 weeks. Phenotypic evaluations were performed during and after the intervention. PA-induced myoblast C2C12 cells were used as an in vitro model. The expression of key enzymes involved in lipid metabolism was assessed in the skeletal muscle of ob/ob mice and DIO mice. RESULTS In ob/ob mice, 4-week exenatide treatment did not improve the body weight and fat mass, but modestly ameliorated intramyocellular lipid deposition and lipid profiles. In DIO mice, it remarkably alleviated the body weight, lipid profiles, and intramyocellular lipid deposition. In the skeletal muscle of these two models, exenatide treatment activated the AMP-activated protein kinase (AMPK) signaling pathway, stimulated lipid oxidation enzymes, and upregulated the insulin signaling pathway. In vitro, exendin-4 activated the AMPK signaling pathway and stimulated lipid metabolism to improve lipid accumulation in palmitate-induced myoblast C2C12 cells. CONCLUSIONS Exenatide ameliorated intramyocellular lipid deposition without body weight reduction in ob/ob mice, but alleviated body weight and intramyocellular lipid deposition in DIO mice. The underlying mechanism included the activation of AMPK signaling pathway and improvement in insulin sensitivity, independent of weight loss in ob/ob mice.
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Affiliation(s)
- Fen Xu
- Department of Endocrinology and Metabolism, the Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Diabetology, Guangzhou, China
| | - Huanyi Cao
- Department of Endocrinology and Metabolism, the Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Diabetology, Guangzhou, China
| | - Zonglan Chen
- Department of Endocrinology and Metabolism, the Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Diabetology, Guangzhou, China
| | - Huimin Gu
- Department of Endocrinology and Metabolism, the Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China.,Department of Infectious Diseases, Xiangya Hospital, Central South University, Changsha, China
| | - Wanrong Guo
- Department of Endocrinology and Metabolism, the Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Diabetology, Guangzhou, China
| | - Beisi Lin
- Department of Endocrinology and Metabolism, the Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China.,Guangdong Provincial Key Laboratory of Diabetology, Guangzhou, China
| | - Jianping Weng
- Department of Endocrinology and Metabolism, the Third Affiliated Hospital of Sun Yat-sen University, Guangzhou, China. .,Guangdong Provincial Key Laboratory of Diabetology, Guangzhou, China.
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Liu Z, Xu L, Xu X, Niu Y, Saadeldeen F, Kang W. Effects and mechanisms of iridoid glycosides from Patrinia scabiosaefolia on improving insulin resistance in 3T3-L1 adipocytes. Food Chem Toxicol 2019; 134:110806. [DOI: 10.1016/j.fct.2019.110806] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/09/2019] [Revised: 08/30/2019] [Accepted: 09/05/2019] [Indexed: 11/25/2022]
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8
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Xu L, Wang W, Zhang X, Ke H, Qin Y, You L, Li W, Lu G, Chan WY, Leung PCK, Zhao S, Chen ZJ. Palmitic acid causes insulin resistance in granulosa cells via activation of JNK. J Mol Endocrinol 2019; 62:197-206. [PMID: 30913535 DOI: 10.1530/jme-18-0214] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/21/2019] [Accepted: 03/26/2019] [Indexed: 12/15/2022]
Abstract
Obesity is a worldwide health problem with rising incidence and results in reproductive difficulties. Elevated saturated free fatty acids (FFAs) in obesity can cause insulin resistance (IR) in peripheral tissues. The high intra-follicular saturated FFAs may also account for IR in ovarian granulosa cells (GCs). In the present study, we investigated the relationship between saturated FFAs and IR in GCs by the use of palmitic acid (PA). We demonstrated that the glucose uptake in cultured GCs and lactate accumulation in the culture medium were stimulated by insulin, but the effects of insulin were attenuated by PA treatment. Besides, insulin-induced phosphorylation of Akt was reduced by PA in a dose- and time-dependent manner. Furthermore, PA increased phosphorylation of JNK and JNK blockage rescued the phosphorylation of Akt which was downregulated by PA. These findings highlighted the negative effect of PA on GCs metabolism and may partially account for the obesity-related reproductive disorders.
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Affiliation(s)
- Lan Xu
- Center for Reproductive Medicine, Shandong University, Shandong Provincial Hospital Affiliated to Shandong University, National Research Center for Assisted Reproductive Technology and Reproductive Genetics, The Key Laboratory of Reproductive Endocrinology (Shandong University), Ministry of Education, Jinan, China
| | - Wenting Wang
- Center for Reproductive Medicine, Shandong University, Shandong Provincial Hospital Affiliated to Shandong University, National Research Center for Assisted Reproductive Technology and Reproductive Genetics, The Key Laboratory of Reproductive Endocrinology (Shandong University), Ministry of Education, Jinan, China
- The Second Hospital of Shandong University, Jinan, China
| | - Xinyue Zhang
- Center for Reproductive Medicine, Shandong University, Shandong Provincial Hospital Affiliated to Shandong University, National Research Center for Assisted Reproductive Technology and Reproductive Genetics, The Key Laboratory of Reproductive Endocrinology (Shandong University), Ministry of Education, Jinan, China
| | - Hanni Ke
- Center for Reproductive Medicine, Shandong University, Shandong Provincial Hospital Affiliated to Shandong University, National Research Center for Assisted Reproductive Technology and Reproductive Genetics, The Key Laboratory of Reproductive Endocrinology (Shandong University), Ministry of Education, Jinan, China
| | - Yingying Qin
- Center for Reproductive Medicine, Shandong University, Shandong Provincial Hospital Affiliated to Shandong University, National Research Center for Assisted Reproductive Technology and Reproductive Genetics, The Key Laboratory of Reproductive Endocrinology (Shandong University), Ministry of Education, Jinan, China
| | - Li You
- Center for Reproductive Medicine, Shandong University, Shandong Provincial Hospital Affiliated to Shandong University, National Research Center for Assisted Reproductive Technology and Reproductive Genetics, The Key Laboratory of Reproductive Endocrinology (Shandong University), Ministry of Education, Jinan, China
| | - Weiping Li
- Department of Obstetrics and Gynecology, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai, China
| | - Gang Lu
- The CUHK-SDU Joint Laboratory on Reproductive Genetics, School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Wai-Yee Chan
- The CUHK-SDU Joint Laboratory on Reproductive Genetics, School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Peter C K Leung
- Department of Obstetrics and Gynecology, University of British Columbia, BC Children's Hospital Research Institute, Vancouver, Canada
| | - Shidou Zhao
- Center for Reproductive Medicine, Shandong University, Shandong Provincial Hospital Affiliated to Shandong University, National Research Center for Assisted Reproductive Technology and Reproductive Genetics, The Key Laboratory of Reproductive Endocrinology (Shandong University), Ministry of Education, Jinan, China
- The CUHK-SDU Joint Laboratory on Reproductive Genetics, School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong SAR, China
| | - Zi-Jiang Chen
- Center for Reproductive Medicine, Shandong University, Shandong Provincial Hospital Affiliated to Shandong University, National Research Center for Assisted Reproductive Technology and Reproductive Genetics, The Key Laboratory of Reproductive Endocrinology (Shandong University), Ministry of Education, Jinan, China
- Center for Reproductive Medicine, Ren Ji Hospital, School of Medicine, Shanghai Jiao Tong University, Shanghai Key Laboratory for Assisted Reproduction and Reproductive Genetics, Shanghai, China
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Liu L, Yao L, Wang S, Chen Z, Han T, Ma P, Jiang L, Yuan C, Li J, Ke D, Li C, Yamahara J, Li Y, Wang J. 6‐Gingerol Improves Ectopic Lipid Accumulation, Mitochondrial Dysfunction, and Insulin Resistance in Skeletal Muscle of Ageing Rats: Dual Stimulation of the AMPK/PGC‐1α Signaling Pathway via Plasma Adiponectin and Muscular AdipoR1. Mol Nutr Food Res 2019; 63:e1800649. [DOI: 10.1002/mnfr.201800649] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2018] [Revised: 12/06/2018] [Indexed: 12/11/2022]
Affiliation(s)
- Li Liu
- Chongqing Key Laboratory of Traditional Chinese Medicine for Prevention and Cure of Metabolic DiseasesCollege of Traditional Chinese MedicineChongqing Medical University Chongqing China
- Faculty of Basic Medical SciencesChongqing Medical University Chongqing China
| | - Ling Yao
- Chongqing Key Laboratory of Traditional Chinese Medicine for Prevention and Cure of Metabolic DiseasesCollege of Traditional Chinese MedicineChongqing Medical University Chongqing China
| | - Shang Wang
- Chongqing Key Laboratory of Traditional Chinese Medicine for Prevention and Cure of Metabolic DiseasesCollege of Traditional Chinese MedicineChongqing Medical University Chongqing China
- Faculty of Basic Medical SciencesChongqing Medical University Chongqing China
| | - Zhiwei Chen
- Chongqing Key Laboratory of Traditional Chinese Medicine for Prevention and Cure of Metabolic DiseasesCollege of Traditional Chinese MedicineChongqing Medical University Chongqing China
| | - Tingli Han
- Department of ObstetricsThe First Affiliated Hospital of Chongqing Medical University Chongqing China
| | - Peng Ma
- Chongqing Key Laboratory of Traditional Chinese Medicine for Prevention and Cure of Metabolic DiseasesCollege of Traditional Chinese MedicineChongqing Medical University Chongqing China
- Faculty of Basic Medical SciencesChongqing Medical University Chongqing China
| | - Lirong Jiang
- Chongqing Key Laboratory of Traditional Chinese Medicine for Prevention and Cure of Metabolic DiseasesCollege of Traditional Chinese MedicineChongqing Medical University Chongqing China
- Faculty of Basic Medical SciencesChongqing Medical University Chongqing China
| | - Chunlin Yuan
- Chongqing Key Laboratory of Traditional Chinese Medicine for Prevention and Cure of Metabolic DiseasesCollege of Traditional Chinese MedicineChongqing Medical University Chongqing China
| | - Jinxiu Li
- Chongqing Key Laboratory of Traditional Chinese Medicine for Prevention and Cure of Metabolic DiseasesCollege of Traditional Chinese MedicineChongqing Medical University Chongqing China
| | - Dazhi Ke
- The Second Affiliated HospitalChongqing Medical University Chongqing China
| | - Chunli Li
- Institute of Life SciencesChongqing Medical University Chongqing China
| | | | - Yuhao Li
- Endocrinology and Metabolism GroupSydney Institute of Health Sciences/Sydney Institute of Traditional Chinese Medicine Sydney Australia
| | - Jianwei Wang
- Chongqing Key Laboratory of Traditional Chinese Medicine for Prevention and Cure of Metabolic DiseasesCollege of Traditional Chinese MedicineChongqing Medical University Chongqing China
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Kelsey I, Zbinden M, Byles V, Torrence M, Manning BD. mTORC1 suppresses PIM3 expression via miR-33 encoded by the SREBP loci. Sci Rep 2017; 7:16112. [PMID: 29170467 PMCID: PMC5701013 DOI: 10.1038/s41598-017-16398-y] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2017] [Accepted: 11/13/2017] [Indexed: 12/31/2022] Open
Abstract
The mechanistic target of rapamycin complex 1 (mTORC1) is a central regulator of cell growth that is often aberrantly activated in cancer. However, mTORC1 inhibitors, such as rapamycin, have limited effectiveness as single agent cancer therapies, with feedback mechanisms inherent to the signaling network thought to diminish the anti-tumor effects of mTORC1 inhibition. Here, we identify the protein kinase and proto-oncogene PIM3 as being repressed downstream of mTORC1 signaling. PIM3 expression is suppressed in cells with loss of the tuberous sclerosis complex (TSC) tumor suppressors, which exhibit growth factor-independent activation of mTORC1, and in the mouse liver upon feeding-induced activation of mTORC1. Inhibition of mTORC1 with rapamycin induces PIM3 transcript and protein levels in a variety of settings. Suppression of PIM3 involves the sterol regulatory element-binding (SREBP) transcription factors SREBP1 and 2, whose activation and mRNA expression are stimulated by mTORC1 signaling. We find that PIM3 repression is mediated by miR-33, an intronic microRNA encoded within the SREBP loci, the expression of which is decreased with rapamycin. These results demonstrate that PIM3 is induced upon mTORC1 inhibition, with potential implications for the effects of mTORC1 inhibitors in TSC, cancers, and the many other disease settings influenced by aberrant mTORC1 signaling.
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Affiliation(s)
- Ilana Kelsey
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Marie Zbinden
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Vanessa Byles
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Margaret Torrence
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA
| | - Brendan D Manning
- Department of Genetics and Complex Diseases, Harvard T.H. Chan School of Public Health, Boston, MA, USA.
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Tang W, Tang S, Wang H, Ge Z, Zhu D, Bi Y. Insulin restores UCP3 activity and decreases energy surfeit to alleviate lipotoxicity in skeletal muscle. Int J Mol Med 2017; 40:2000-2010. [PMID: 29039450 DOI: 10.3892/ijmm.2017.3169] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2017] [Accepted: 09/19/2017] [Indexed: 11/06/2022] Open
Abstract
An early insulin regimen ameliorates glucotoxicity but also lipotoxicity in type 2 diabetes; however, the underlying mechanism remains elusive. In the present study, we investigated the role of mitochondria in lipid regulation following early insulin administration in insulin-resistant skeletal muscle cells. Male C57BL/6 mice, fed a high-fat diet (HFD) for 8 weeks, were treated with insulin for 3 weeks, and L6 myotubes cultured with palmitate (PA) for 24 h were incubated with insulin for another 12 h. The results showed that insulin facilitated systemic glucose disposal and attenuated muscular triglyceride accumulation in vivo. Recovery of AMP-activated protein kinase (AMPK) phosphorylation, inhibition of sterol-regulated element binding protein-1c (SREBP-1c) and increased carnitine palmitoyltransferase‑1B (CPT1B) expression were observed after insulin administration. Moreover, increased ATP concentration and cellular energy charge elicited by over-nutrition were suppressed by insulin. Despite maintaining respiratory complex activities, insulin restored muscular uncoupling protein 3 (UCP3) protein expression in vitro and in vivo. By contrast, knockdown of UCP3 abrogated insulin-induced restoration of AMPK phosphorylation in vitro. Importantly, the PA-induced decrease in UCP3 was blocked by the proteasome inhibitor MG132, and insulin reduced UCP3 ubiquitination, thereby prohibiting its degradation. Our findings, focusing on energy balance, provide a mechanistic understanding of the promising effect of early insulin initiation on lipotoxicity. Insulin, by recovering UCP3 activity, alleviated energy surfeit and potentiated AMPK-mediated lipid homeostasis in skeletal muscle cells following exposure to PA and in gastrocnemius of mice fed HFD.
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Affiliation(s)
- Wenjuan Tang
- Department of Endocrinology, Drum Tower Hospital Affiliated to Nanjing University Medical School, Nanjing, Jiangsu 210008, P.R. China
| | - Sunyinyan Tang
- Department of Endocrinology, Drum Tower Hospital Affiliated to Nanjing University Medical School, Nanjing, Jiangsu 210008, P.R. China
| | - Hongdong Wang
- Department of Endocrinology, Drum Tower Hospital Affiliated to Nanjing University Medical School, Nanjing, Jiangsu 210008, P.R. China
| | - Zhijuan Ge
- Department of Endocrinology, Drum Tower Hospital Affiliated to Nanjing University Medical School, Nanjing, Jiangsu 210008, P.R. China
| | - Dalong Zhu
- Department of Endocrinology, Drum Tower Hospital Affiliated to Nanjing University Medical School, Nanjing, Jiangsu 210008, P.R. China
| | - Yan Bi
- Department of Endocrinology, Drum Tower Hospital Affiliated to Nanjing University Medical School, Nanjing, Jiangsu 210008, P.R. China
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12
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Liu C, Ma J, Sun J, Cheng C, Feng Z, Jiang H, Yang W. Flavonoid-Rich Extract of Paulownia fortunei Flowers Attenuates Diet-Induced Hyperlipidemia, Hepatic Steatosis and Insulin Resistance in Obesity Mice by AMPK Pathway. Nutrients 2017; 9:nu9090959. [PMID: 28867797 PMCID: PMC5622719 DOI: 10.3390/nu9090959] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Revised: 08/01/2017] [Accepted: 08/28/2017] [Indexed: 12/30/2022] Open
Abstract
The flavonoid-rich extract from Paulownia fortunei flowers (EPF) has been reported to prevent obesity and other lipid metabolism disease. However, the mechanism of its protective effects is not yet clear. The objective of this study was to investigate molecular factors involved in the hypoglycemic and hypolipidemic effects of EPF in obese mice fed a high-fat diet (HFD). Male h ICR (Institute of Cancer Research) mice were fed a HFD containing or not containing the EPF (50 or 100 mg/kg) for eight weeks. EPF reduced body weight gain, lipid accumulation in livers and levels of lipid, glucose and insulin in plasma as well as reduced insulin resistance as compared with the HFD group. EPF significantly decreased serum aminotransferase activity of the HFD group. We observed that EPF administration significantly increased the level of AMP-activated kinase (AMPK) phosphorylation and prevented fat deposits in livers and HepG2 cells, but these effects were blocked by compound C (an AMPK inhibitor). The protective effects of EPF were probably associated with the decrease in HMGCR, SREBP-1c and FAS expressions and the increase in CPT1 and phosphor-IRS-1 expressions. Our results suggest that EPF might be a potential natural candidate for the treatment and/or prevention of overweight and hepatic and metabolic-related alterations induced by HFD.
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Affiliation(s)
- Chanmin Liu
- School of Life Science, Jiangsu Normal University, No. 101, Shanghai Road, Tangshan New Area, Xuzhou 221116, Jiangsu, China.
| | - Jieqiong Ma
- School of Chemical Engineering, Sichuan University of Science and Engineering, No. 180, Huixing Road, Zigong 643000, Sichuan, China.
| | - Jianmei Sun
- School of Life Science, Jiangsu Normal University, No. 101, Shanghai Road, Tangshan New Area, Xuzhou 221116, Jiangsu, China.
| | - Chao Cheng
- School of Life Science, Jiangsu Normal University, No. 101, Shanghai Road, Tangshan New Area, Xuzhou 221116, Jiangsu, China.
| | - Zhaojun Feng
- School of Life Science, Jiangsu Normal University, No. 101, Shanghai Road, Tangshan New Area, Xuzhou 221116, Jiangsu, China.
| | - Hong Jiang
- School of Life Science, Jiangsu Normal University, No. 101, Shanghai Road, Tangshan New Area, Xuzhou 221116, Jiangsu, China.
| | - Wei Yang
- School of Life Science, Jiangsu Normal University, No. 101, Shanghai Road, Tangshan New Area, Xuzhou 221116, Jiangsu, China.
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13
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Zhang JJ, Hao JJ, Zhang YR, Wang YL, Li MY, Miao HL, Zou XJ, Liang B. Zinc mediates the SREBP-SCD axis to regulate lipid metabolism in Caenorhabditis elegans. J Lipid Res 2017; 58:1845-1854. [PMID: 28710073 DOI: 10.1194/jlr.m077198] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2017] [Revised: 07/12/2017] [Indexed: 12/15/2022] Open
Abstract
Maintenance of lipid homeostasis is crucial for cells in response to lipid requirements or surplus. The SREBP transcription factors play essential roles in regulating lipid metabolism and are associated with many metabolic diseases. However, SREBP regulation of lipid metabolism is still not completely understood. Here, we showed that reduction of SBP-1, the only homolog of SREBPs in Caenorhabditis elegans, surprisingly led to a high level of zinc. On the contrary, zinc reduction by mutation of sur-7, encoding a member of the cation diffusion facilitator (CDF) family, restored the fat accumulation and fatty acid profile of the sbp-1(ep79) mutant. Zinc reduction resulted in iron overload, which thereby directly activated the conversion activity of stearoyl-CoA desaturase (SCD), a main target of SREBP, to promote lipid biosynthesis and accumulation. However, zinc reduction reversely repressed SBP-1 nuclear translocation and further downregulated the transcription expression of SCD for compensation. Collectively, we revealed zinc-mediated regulation of the SREBP-SCD axis in lipid metabolism, distinct from the negative regulation of SREBP-1 or SREBP-2 by phosphatidylcholine or cholesterol, respectively, thereby providing novel insights into the regulation of lipid homeostasis.
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Affiliation(s)
- Jing-Jing Zhang
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences and Yunnan Province Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China.,Department of Hepatobiliary Surgery, Affiliated Hospital of Guangdong Medical University, Zhanjiang 524001, China
| | - Jun-Jun Hao
- State Key Laboratory of Genetic Resources and Evolutionary and Functional Genomics, Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China
| | - Yu-Ru Zhang
- College of Fisheries, Henan Normal University, Xinxiang, Henan 453007, China
| | - Yan-Li Wang
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences and Yunnan Province Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China
| | - Ming-Yi Li
- Department of Hepatobiliary Surgery, Affiliated Hospital of Guangdong Medical University, Zhanjiang 524001, China
| | - Hui-Lai Miao
- Department of Hepatobiliary Surgery, Affiliated Hospital of Guangdong Medical University, Zhanjiang 524001, China
| | - Xiao-Ju Zou
- Department of Life Science and Biotechnology, Key Laboratory of Special Biological Resource Development and Utilization of University in Yunnan Province, Kunming University, Kunming 650214, China
| | - Bin Liang
- Key Laboratory of Animal Models and Human Disease Mechanisms of the Chinese Academy of Sciences and Yunnan Province Kunming Institute of Zoology, Chinese Academy of Sciences, Kunming 650223, China .,Department of Hepatobiliary Surgery, Affiliated Hospital of Guangdong Medical University, Zhanjiang 524001, China
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14
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Tang S, Wu W, Tang W, Ge Z, Wang H, Hong T, Zhu D, Bi Y. Suppression of Rho-kinase 1 is responsible for insulin regulation of the AMPK/SREBP-1c pathway in skeletal muscle cells exposed to palmitate. Acta Diabetol 2017; 54:635-644. [PMID: 28265821 DOI: 10.1007/s00592-017-0976-z] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/09/2016] [Accepted: 02/19/2017] [Indexed: 11/28/2022]
Abstract
AIMS Clinical and experimental data suggest that early insulin therapy could reduce lipotoxicity in subjects and animal models with type 2 diabetes mellitus. However, the underlying mechanisms need to be clarified. Sterol regulatory element-binding protein 1c (SREBP-1c), which is negatively regulated by AMP-activated protein kinase (AMPK), plays a critical role in lipotoxicity and insulin resistance in skeletal muscle cells. Here, we investigated the effect and molecular mechanism of insulin intervention on the AMPK/SREBP-1c pathway in skeletal muscle cells with chronic exposure to palmitic acid (PA). METHODS Male C57BL/6 mice were fed with a high-fat diet for 12 weeks and were then treated with insulin, AMPK inhibitor, or metformin. L6 myotubes incubated with palmitic acid (PA) were treated with insulin or metformin. Dominant-negative AMPKα2 (DN-AMPKα2) lentivirus, AMPKα2 siRNA, or Rho-kinase 1 (ROCK1) siRNA were transfected into PA-treated L6 myotubes. RESULTS We found that the ability of PA to stimulate SREBP-1c and inhibit AMPK was reversed by insulin in L6 cells. Moreover, DN-AMPKα2 lentivirus and AMPKα2 siRNA were transfected into PA-treated L6 myotubes, and the decrease in SREBP-1c expression caused by insulin was blocked by AMPK inhibition independent of the phosphatidylinositol-4,5-biphosphate-3-kinase (PI3K)/AKT pathway. The serine/threonine kinase Rho-kinase (ROCK) 1, a downstream effector of the small G protein RhoA, was activated by PA. Interestingly, knockdown of ROCK1 by siRNA blocked the downregulation of AMPK phosphorylation under PA-treated L6 myotubes, which indicated that ROCK1 mediated the effect of insulin action on AMPK. CONCLUSIONS Our study indicated that insulin reduced lipotoxicity via ROCK1 and then improved AMPK/SREBP-1c signaling in skeletal muscle under PA-induced insulin resistance.
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Affiliation(s)
- Sunyinyan Tang
- Department of Endocrinology, Drum Tower Hospital Affiliated to the Nanjing University Medical School, Nanjing, Jiangsu, People's Republic of China
| | - Wenjun Wu
- Department of Endocrinology, Wuxi People's Hospital of Nanjing Medical University, Wuxi, Jiangsu, People's Republic of China
| | - Wenjuan Tang
- Department of Endocrinology, Drum Tower Hospital Affiliated to the Nanjing University Medical School, Nanjing, Jiangsu, People's Republic of China
| | - Zhijuan Ge
- Department of Endocrinology, Drum Tower Hospital Affiliated to the Nanjing University Medical School, Nanjing, Jiangsu, People's Republic of China
| | - Hongdong Wang
- Department of Endocrinology, Drum Tower Hospital Affiliated to the Nanjing University Medical School, Nanjing, Jiangsu, People's Republic of China
| | - Ting Hong
- Department of Endocrinology, Drum Tower Hospital Affiliated to the Nanjing University Medical School, Nanjing, Jiangsu, People's Republic of China
| | - Dalong Zhu
- Department of Endocrinology, Drum Tower Hospital Affiliated to the Nanjing University Medical School, Nanjing, Jiangsu, People's Republic of China.
| | - Yan Bi
- Department of Endocrinology, Drum Tower Hospital Affiliated to the Nanjing University Medical School, Nanjing, Jiangsu, People's Republic of China.
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15
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Petroleum ether sub-fraction of rosemary extract improves hyperlipidemia and insulin resistance by inhibiting SREBPs. Chin J Nat Med 2016; 14:746-756. [PMID: 28236404 DOI: 10.1016/s1875-5364(16)30089-9] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2016] [Indexed: 11/21/2022]
Abstract
As a culinary and medicinal herb, rosemary is widely used. The present work aimed to investigate the effects of rosemary extracts on metabolic diseases and the underlying mechanisms of action. Liver cells stably expressing SREBP reporter were used to evaluate the inhibitory effects of different fractions of rosemary extracts on SREBP activity. The obese mice induced by Western-type diet were orally administered with rosemary extracts or vehicle for 7 weeks, the plasma and tissue lipids were analyzed. SREBPs and their target genes were measured by quantitative RT-PCR. We demonstrated that the petroleum ether sub-fraction of rosemary extracts (PER) exhibited the best activity in regulating lipid metabolism by inhibiting SREBPs, while water and n-BuOH sub-fraction showed the SREBPs agonist-effect. After PER treatment, there was a significant reduction of total SREBPs in liver cells. PER not only decreased SREBPs nuclear abundance, but also inhibited their activity, resulting in decreased expression of SREBP-1c and SREBP-2 target genes in vitro and in vivo. Inhibiting SREBPs by PER decreased the total triglycerides and cholesterol contents of the liver cells. In the mice fed with Western-type diet, PER treatment decreased TG, TC, ALT, glucose, and insulin in blood, and improved glucose tolerance and insulin sensitivity. Furthermore, PER treatment also decreased lipid contents in liver, brown adipose tissue, and white adipose tissue. Our results from the present study suggested that petroleum ether fraction of rosemary extracts exhibited the best potential of improving lipid metabolism by inhibiting SREBPs activity.
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16
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The expression of genes involved in jejunal lipogenesis and lipoprotein synthesis is altered in morbidly obese subjects with insulin resistance. J Transl Med 2015; 95:1409-17. [PMID: 26367490 DOI: 10.1038/labinvest.2015.115] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Revised: 07/03/2015] [Accepted: 07/28/2015] [Indexed: 12/28/2022] Open
Abstract
The dyslipidemia associated with type 2 diabetes mellitus (T2DM) is an important risk factor for atherosclerotic cardiovascular disease. However, until now little attention has been paid to the role that the intestine might have. The aim of this research was to determine the relation between insulin resistance and intestinal de novo lipogenesis/lipoprotein synthesis in morbidly obese subjects and to study the effect of insulin on these processes. Jejunal mRNA expression of the different genes involved in the intestinal de novo lipogenesis/lipoprotein synthesis was analyzed in three groups of morbidly obese subjects: Group 1 with low insulin resistance (MO-low-IR), group 2 with high insulin resistance (MO-high-IR), and group 3 with T2DM and treatment with metformin (MO-metf-T2DM). In addition, intestinal epithelial cells (IECs) from MO-low-IR were incubated with different doses of insulin/glucose. In Group 2 (MO-high-IR), the jejunal mRNA expression levels of apo A-IV, ATP-citrate lyase (ACLY), pyruvate dehydrogenase (lipoamide) beta (PDHB), and sterol regulatory element-binding protein-1c (SREBP-1c) were significantly higher and acetyl-CoA carboxylase alpha (ACC1) and fatty-acid synthase lower than in Group 1 (MO-low-IR). In Group 3 (MO-metf-T2DM), only the ACLY and PDHB mRNA expressions were significantly higher than in Group 1 (MO-low-IR). The mRNA expression of most of the genes studied was significantly linked to insulin and glucose levels. The incubation of IEC with different doses of insulin and glucose produced a higher expression of diacylglycerol acyltransferase 2, microsomal triglyceride transfer protein, apo A-IV, SREBP-1c, and ACC1 when both, glucose and insulin, were at a high concentration. However, with only high insulin levels, there were higher apo A-IV, PDHB and SREBP-1c expressions, and a lower ACLY expression. In conclusion, the jejunum of MO-high-IR has a decreased mRNA expression of genes involved in de novo fatty-acid synthesis and an increase of genes involved in acetyl-CoA and lipoprotein synthesis. This effect is attenuated by metformin. In addition, the expression of most of the genes studied was found to be regulated by insulin.
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17
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Soyal SM, Nofziger C, Dossena S, Paulmichl M, Patsch W. Targeting SREBPs for treatment of the metabolic syndrome. Trends Pharmacol Sci 2015; 36:406-16. [PMID: 26005080 DOI: 10.1016/j.tips.2015.04.010] [Citation(s) in RCA: 67] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 04/20/2015] [Accepted: 04/23/2015] [Indexed: 12/11/2022]
Abstract
Over the past few decades, mortality resulting from cardiovascular disease (CVD) steadily decreased in western countries; however, in recent years, the decline has become offset by the increase in obesity. Obesity is strongly associated with the metabolic syndrome and its atherogenic dyslipidemia resulting from insulin resistance. While lifestyle treatment would be effective, drugs targeting individual risk factors are often required. Such treatment may result in polypharmacy. Novel approaches are directed towards the treatment of several risk factors with one drug. Studies in animal models and humans suggest a central role for sterol regulatory-element binding proteins (SREBPs) in the pathophysiology of the metabolic syndrome. Four recent studies targeting the maturation or transcriptional activities of SREBPs provide proof of concept for the efficacy of SREBP inhibition in this syndrome.
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Affiliation(s)
- Selma M Soyal
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Salzburg, Austria
| | - Charity Nofziger
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Salzburg, Austria
| | - Silvia Dossena
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Salzburg, Austria
| | - Markus Paulmichl
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Salzburg, Austria
| | - Wolfgang Patsch
- Institute of Pharmacology and Toxicology, Paracelsus Medical University, Salzburg, Austria.
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18
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Wu W, Tang S, Shi J, Yin W, Cao S, Bu R, Zhu D, Bi Y. Metformin attenuates palmitic acid-induced insulin resistance in L6 cells through the AMP-activated protein kinase/sterol regulatory element-binding protein-1c pathway. Int J Mol Med 2015; 35:1734-40. [PMID: 25891779 DOI: 10.3892/ijmm.2015.2187] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2014] [Accepted: 04/09/2015] [Indexed: 11/05/2022] Open
Abstract
AMP-activated protein kinase (AMPK) is an important effector of metformin action on glucose uptake in skeletal muscle cells. We recently reported that metformin improved insulin receptor substrate-1 (IRS-1)-associated insulin signaling by downregulating sterol regulatory element-binding protein-1c (SREBP-1c) expression. In this study, we investigated whether AMPK activation and SREBP-1c inhibition contribute to the beneficial effects of metformin on IRS-1-associated insulin signaling in L6 myotubes. L6 muscle cells were incubated with palmitic acid (PA) to induce insulin resistance and then treated with metformin and/or the AMPK inhibitor, compound C. AMPK, SREBP-1c, IRS-1 and Akt protein expression levels were determined by western blot analysis. The effects of metformin on SREBP-1c gene transcription were determined by a luciferase reporter assay. Glucose uptake was evaluated using the 2-NBDG method. In the PA-treated L6 cells, metformin treatment enhanced AMPK phosphorylation, reduced SREBP-1c expression and increased IRS-1 and Akt protein expression, whereas treatment with compound C blocked the effects of metformin on SREBP-1c expression and the IRS-1 and Akt levels. Moreover, metformin suppressed SREBP-1c promoter activity and promoted glucose uptake through AMPK. The results from this study demonstrate that metformin ameliorates PA-induced insulin resistance through the activation of AMPK and the suppression of SREBP-1c in skeletal muscle cells.
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Affiliation(s)
- Wenjun Wu
- Department of Endocrinology, Drum Tower Clinical Medical College of Nanjing Medical University, Nanjing, Jiangsu, P.R. China
| | - Sunyinyan Tang
- Department of Endocrinology, Drum Tower Hospital Affiliated to Nanjing University Medical School, Nanjing, Jiangsu, P.R. China
| | - Junfeng Shi
- Department of Oncology, Nanjing First Hospital of Nanjing Medical University, Nanjing, Jiangsu, P.R. China
| | - Wenwen Yin
- Department of Endocrinology, Drum Tower Clinical Medical College of Nanjing Medical University, Nanjing, Jiangsu, P.R. China
| | - Shu Cao
- Department of Endocrinology, Drum Tower Clinical Medical College of Nanjing Medical University, Nanjing, Jiangsu, P.R. China
| | - Ruifang Bu
- Department of Endocrinology, Wuxi People's Hospital of Nanjing Medical University, Wuxi, Jiangsu, P.R. China
| | - Dalong Zhu
- Department of Endocrinology, Drum Tower Clinical Medical College of Nanjing Medical University, Nanjing, Jiangsu, P.R. China
| | - Yan Bi
- Department of Endocrinology, Drum Tower Clinical Medical College of Nanjing Medical University, Nanjing, Jiangsu, P.R. China
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Yoon JH, Kim D, Jang JH, Ghim J, Park S, Song P, Kwon Y, Kim J, Hwang D, Bae YS, Suh PG, Berggren PO, Ryu SH. Proteomic analysis of the palmitate-induced myotube secretome reveals involvement of the annexin A1-formyl peptide receptor 2 (FPR2) pathway in insulin resistance. Mol Cell Proteomics 2015; 14:882-92. [PMID: 25616869 DOI: 10.1074/mcp.m114.039651] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2014] [Indexed: 11/06/2022] Open
Abstract
Elevated levels of the free fatty acid palmitate are found in the plasma of obese patients and induce insulin resistance. Skeletal muscle secretes myokines as extracellular signaling mediators in response to pathophysiological conditions. Here, we identified and characterized the skeletal muscle secretome in response to palmitate-induced insulin resistance. Using a quantitative proteomic approach, we identified 36 secretory proteins modulated by palmitate-induced insulin resistance. Bioinformatics analysis revealed that palmitate-induced insulin resistance induced cellular stress and modulated secretory events. We found that the decrease in the level of annexin A1, a secretory protein, depended on palmitate, and that annexin A1 and its receptor, formyl peptide receptor 2 agonist, played a protective role in the palmitate-induced insulin resistance of L6 myotubes through PKC-θ modulation. In mice fed with a high-fat diet, treatment with the formyl peptide receptor 2 agonist improved systemic insulin sensitivity. Thus, we identified myokine candidates modulated by palmitate-induced insulin resistance and found that the annexin A1- formyl peptide receptor 2 pathway mediated the insulin resistance of skeletal muscle, as well as systemic insulin sensitivity.
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Affiliation(s)
| | - Dayea Kim
- From the ‡Department of Life Sciences
| | - Jin-Hyeok Jang
- §School of Interdisciplinary Bioscience and Bioengineering
| | | | | | | | | | - Jaeyoon Kim
- ‖The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm SE-171 77, Sweden
| | - Daehee Hwang
- §School of Interdisciplinary Bioscience and Bioengineering, ¶Department of Chemical Engineering, Pohang University of Science and Technology (POSTECH), Pohang, Kyungbuk 790-784, Republic of Korea, ‖‖Center for Plant Aging Research, Institute for Basic Science and Department of New Biology, Daegu Gyeongbuk Institute of Science and Technology, Daegu, 711-873, Republic of Korea
| | - Yoe-Sik Bae
- **Department of Biological Science, Sungkyunkwan University, Suwon 440-746, Republic of Korea, ‡‡Samsung Advanced Institute for Health Sciences and Technology, Sungkyunkwan University, Seoul 135-710, Republic of Korea
| | - Pann-Ghill Suh
- §§School of Life Sciences, Ulsan National Institute of Science and Technology, Ulsan, 689-798, Republic of Korea
| | - Per-Olof Berggren
- ‖The Rolf Luft Research Center for Diabetes and Endocrinology, Karolinska Institutet, Stockholm SE-171 77, Sweden, Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk, 790-784, Republic of Korea
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