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Kim YS, Ko B, Kim DJ, Tak J, Han CY, Cho JY, Kim W, Kim SG. Induction of the hepatic aryl hydrocarbon receptor by alcohol dysregulates autophagy and phospholipid metabolism via PPP2R2D. Nat Commun 2022; 13:6080. [PMID: 36241614 PMCID: PMC9568535 DOI: 10.1038/s41467-022-33749-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 09/30/2022] [Indexed: 12/24/2022] Open
Abstract
Disturbed lipid metabolism precedes alcoholic liver injury. Whether and how AhR alters degradation of lipids, particularly phospho-/sphingo-lipids during alcohol exposure, was not explored. Here, we show that alcohol consumption in mice results in induction and activation of aryl hydrocarbon receptor (AhR) in the liver, and changes the hepatic phospho-/sphingo-lipids content. The levels of kynurenine, an endogenous AhR ligand, are elevated with increased hepatic tryptophan metabolic enzymes in alcohol-fed mice. Either alcohol or kynurenine treatment promotes AhR activation with autophagy dysregulation via AMPK. Protein Phosphatase 2 Regulatory Subunit-Bdelta (Ppp2r2d) is identified as a transcriptional target of AhR. Consequently, PPP2R2D-dependent AMPKα dephosphorylation causes autophagy inhibition and mitochondrial dysfunction. Hepatocyte-specific AhR ablation attenuates steatosis, which is associated with recovery of phospho-/sphingo-lipids content. Changes of AhR targets are corroborated using patient specimens. Overall, AhR induction by alcohol inhibits autophagy in hepatocytes through AMPKα, which is mediated by Ppp2r2d gene transactivation, revealing an AhR-dependent metabolism of phospho-/sphingo-lipids.
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Affiliation(s)
- Yun Seok Kim
- grid.31501.360000 0004 0470 5905Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine, Seoul, 03080 Korea ,grid.31501.360000 0004 0470 5905Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, 03080 Republic of Korea ,grid.31501.360000 0004 0470 5905College of Pharmacy, Seoul National University, Seoul, Republic of Korea
| | - Bongsub Ko
- grid.31501.360000 0004 0470 5905Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine, Seoul, 03080 Korea
| | - Da Jung Kim
- grid.31501.360000 0004 0470 5905Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine, Seoul, 03080 Korea ,grid.412484.f0000 0001 0302 820XMetabolomics Core Facility, Department of Transdisciplinary Research and Collaboration, Biomedical Research Institute, Seoul National University Hospital, Seoul, 03082 Korea
| | - Jihoon Tak
- grid.31501.360000 0004 0470 5905College of Pharmacy, Seoul National University, Seoul, Republic of Korea ,grid.255168.d0000 0001 0671 5021College of Pharmacy and Integrated Research Institute for Drug Development, Dongguk University-Seoul, Goyang-si, Kyeonggi-do 10326 Republic of Korea
| | - Chang Yeob Han
- grid.31501.360000 0004 0470 5905College of Pharmacy, Seoul National University, Seoul, Republic of Korea ,grid.411545.00000 0004 0470 4320School of Pharmacy and Institute of New Drug Development, Jeonbuk National University, 567 Baekje-daero, Deokjin-gu, Jeonju-si, Jeollabuk-do, 54896 Korea
| | - Joo-Youn Cho
- grid.31501.360000 0004 0470 5905Department of Clinical Pharmacology and Therapeutics, Seoul National University College of Medicine, Seoul, 03080 Korea ,grid.31501.360000 0004 0470 5905Department of Biomedical Sciences, Seoul National University College of Medicine, Seoul, 03080 Republic of Korea
| | - Won Kim
- grid.31501.360000 0004 0470 5905Division of Gastroenterology and Hepatology, Department of Internal Medicine, Seoul National University College of Medicine, Seoul Metropolitan Government Seoul National University Boramae Medical Center, Seoul, Korea
| | - Sang Geon Kim
- grid.255168.d0000 0001 0671 5021College of Pharmacy and Integrated Research Institute for Drug Development, Dongguk University-Seoul, Goyang-si, Kyeonggi-do 10326 Republic of Korea
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Chen YY, Chen XG, Zhang S. Druggability of lipid metabolism modulation against renal fibrosis. Acta Pharmacol Sin 2022; 43:505-519. [PMID: 33990764 PMCID: PMC8888625 DOI: 10.1038/s41401-021-00660-1] [Citation(s) in RCA: 18] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2020] [Accepted: 03/16/2021] [Indexed: 02/08/2023] Open
Abstract
Renal fibrosis contributes to progressive damage to renal structure and function. It is a common pathological process as chronic kidney disease develops into kidney failure, irrespective of diverse etiologies, and eventually leads to death. However, there are no effective drugs for renal fibrosis treatment at present. Lipid aggregation in the kidney and consequent lipotoxicity always accompany chronic kidney disease and fibrosis. Numerous studies have revealed that restoring the defective fatty acid oxidation in the kidney cells can mitigate renal fibrosis. Thus, it is an important strategy to reverse the dysfunctional lipid metabolism in the kidney, by targeting critical regulators of lipid metabolism. In this review, we highlight the potential "druggability" of lipid metabolism to ameliorate renal fibrosis and provide current pre-clinical evidence, exemplified by some representative druggable targets and several other metabolic regulators with anti-renal fibrosis roles. Then, we introduce the preliminary progress of noncoding RNAs as promising anti-renal fibrosis drug targets from the perspective of lipid metabolism. Finally, we discuss the prospects and deficiencies of drug targeting lipid reprogramming in the kidney.
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Affiliation(s)
- Yuan-yuan Chen
- grid.506261.60000 0001 0706 7839State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union medical college, Beijing, 100050 China
| | - Xiao-guang Chen
- grid.506261.60000 0001 0706 7839State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union medical college, Beijing, 100050 China
| | - Sen Zhang
- State Key Laboratory of Bioactive Substances and Functions of Natural Medicines, Institute of Materia Medica, Chinese Academy of Medical Sciences & Peking Union medical college, Beijing, 100050, China.
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Kim TH, Koo JH, Heo MJ, Han CY, Kim YI, Park SY, Cho IJ, Lee CH, Choi CS, Lee JW, Kim W, Cho JY, Kim SG. Overproduction of inter-α-trypsin inhibitor heavy chain 1 after loss of Gα 13 in liver exacerbates systemic insulin resistance in mice. Sci Transl Med 2020; 11:11/513/eaan4735. [PMID: 31597753 DOI: 10.1126/scitranslmed.aan4735] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2017] [Revised: 02/18/2018] [Accepted: 03/22/2019] [Indexed: 12/27/2022]
Abstract
The impact of liver disease on whole-body glucose homeostasis is largely attributed to dysregulated release of secretory proteins in response to metabolic stress. The molecular cues linking liver to whole-body glucose metabolism remain elusive. We found that expression of G protein α-13 (Gα13) was decreased in the liver of mice and humans with diabetes. Liver-specific deletion of the Gna13 gene in mice resulted in systemic glucose intolerance. Comparative secretome analysis identified inter-α-trypsin inhibitor heavy chain 1 (ITIH1) as a protein secreted by liver that was responsible for systemic insulin resistance in Gna13-deficient mice. Liver expression of ITIH1 positively correlated with surrogate markers for diabetes in patients with impaired glucose tolerance or overt diabetes. Mechanistically, a decrease in hepatic Gα13 caused ITIH1 oversecretion by liver through induction of O-GlcNAc transferase expression, facilitating ITIH1 deposition on the hyaluronan surrounding mouse adipose tissue and skeletal muscle. Neutralization of secreted ITIH1 ameliorated glucose intolerance in obese mice. Our findings demonstrate systemic insulin resistance in mice resulting from liver-secreted ITIH1 downstream of Gα13 and its reversal by ITIH1 neutralization.
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Affiliation(s)
- Tae Hyun Kim
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul 08826, Korea
| | - Ja Hyun Koo
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul 08826, Korea
| | - Mi Jeong Heo
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul 08826, Korea
| | - Chang Yeob Han
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul 08826, Korea
| | - Yong-In Kim
- Department of Biochemistry, BK21 PLUS Program for Creative Veterinary Science Research and Research Institute for Veterinary Science, College of Veterinary Medicine, Seoul National University , Seoul 08826, Korea
| | - Shi-Young Park
- Korea Mouse Metabolic Phenotyping Center, Lee Gil Ya Cancer and Diabetes Institute, Gachon University School of Medicine, Incheon 21999, Korea
| | - Il Je Cho
- College of Korean Medicine, Daegu Haany University, Gyeongsan, Gyeongsangbuk-do 38610, Korea
| | - Chang Ho Lee
- Department of Pharmacology, Institute of Biomedical Science, College of Medicine, Hanyang University, Seoul, Korea
| | - Cheol Soo Choi
- Korea Mouse Metabolic Phenotyping Center, Lee Gil Ya Cancer and Diabetes Institute, Gachon University School of Medicine, Incheon 21999, Korea.,Endocrinology, Internal Medicine, Gachon University Gil Medical Center, Incheon 21565, Korea
| | - Jung Weon Lee
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul 08826, Korea.,Interdisciplinary Program in Genetic Engineering, Seoul National University, Seoul 08826, Korea
| | - Won Kim
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, College of Medicine, Seoul National University, Seoul Metropolitan Government Boramae Medical Center, Seoul, Korea.
| | - Je-Yoel Cho
- Department of Biochemistry, BK21 PLUS Program for Creative Veterinary Science Research and Research Institute for Veterinary Science, College of Veterinary Medicine, Seoul National University , Seoul 08826, Korea
| | - Sang Geon Kim
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul 08826, Korea.
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Kim TH, Yang YM, Han CY, Koo JH, Oh H, Kim SS, You BH, Choi YH, Park TS, Lee CH, Kurose H, Noureddin M, Seki E, Wan YJY, Choi CS, Kim SG. Gα12 ablation exacerbates liver steatosis and obesity by suppressing USP22/SIRT1-regulated mitochondrial respiration. J Clin Invest 2018; 128:5587-5602. [PMID: 30300140 DOI: 10.1172/jci97831] [Citation(s) in RCA: 37] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2017] [Accepted: 10/02/2018] [Indexed: 12/20/2022] Open
Abstract
Nonalcoholic fatty liver disease (NAFLD) arises from mitochondrial dysfunction under sustained imbalance between energy intake and expenditure, but the underlying mechanisms controlling mitochondrial respiration have not been entirely understood. Heterotrimeric G proteins converge with activated GPCRs to modulate cell-signaling pathways to maintain metabolic homeostasis. Here, we investigated the regulatory role of G protein α12 (Gα12) on hepatic lipid metabolism and whole-body energy expenditure in mice. Fasting increased Gα12 levels in mouse liver. Gα12 ablation markedly augmented fasting-induced hepatic fat accumulation. cDNA microarray analysis from Gna12-KO liver revealed that the Gα12-signaling pathway regulated sirtuin 1 (SIRT1) and PPARα, which are responsible for mitochondrial respiration. Defective induction of SIRT1 upon fasting was observed in the liver of Gna12-KO mice, which was reversed by lentivirus-mediated Gα12 overexpression in hepatocytes. Mechanistically, Gα12 stabilized SIRT1 protein through transcriptional induction of ubiquitin-specific peptidase 22 (USP22) via HIF-1α increase. Gα12 levels were markedly diminished in liver biopsies from NAFLD patients. Consistently, Gna12-KO mice fed a high-fat diet displayed greater susceptibility to diet-induced liver steatosis and obesity due to decrease in energy expenditure. Our results demonstrate that Gα12 regulates SIRT1-dependent mitochondrial respiration through HIF-1α-dependent USP22 induction, identifying Gα12 as an upstream molecule that contributes to the regulation of mitochondrial energy expenditure.
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Affiliation(s)
- Tae Hyun Kim
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, South Korea
| | - Yoon Mee Yang
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, South Korea.,Division of Digestive and Liver Diseases, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Chang Yeob Han
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, South Korea.,Department of Pharmacology, School of Medicine, Wonkwang University, Iksan, Jeonbuk, South Korea
| | - Ja Hyun Koo
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, South Korea
| | - Hyunhee Oh
- Korea Mouse Metabolic Phenotyping Center, Lee Gil Ya Cancer and Diabetes Institute, Gachon University of Medicine and Science, Incheon, South Korea
| | - Su Sung Kim
- Korea Mouse Metabolic Phenotyping Center, Lee Gil Ya Cancer and Diabetes Institute, Gachon University of Medicine and Science, Incheon, South Korea
| | - Byoung Hoon You
- College of Pharmacy, Dongguk University, Ilsan Dong-Gu, Goyang, Gyeoggi-Do, South Korea
| | - Young Hee Choi
- College of Pharmacy, Dongguk University, Ilsan Dong-Gu, Goyang, Gyeoggi-Do, South Korea
| | - Tae-Sik Park
- Department of Life Science, Gachon University, Seongnam, Gyeonggi-Do, South Korea
| | - Chang Ho Lee
- College of Medicine, Hanyang University, Seoul, South Korea
| | - Hitoshi Kurose
- Department of Pharmacology and Toxicology, Graduate School of Pharmaceutical Sciences, Kyushu University, Fukuoka, Japan
| | - Mazen Noureddin
- Fatty Liver Disease Program, Division of Digestive and Liver Diseases, Department of Medicine, Comprehensive Transplant Center, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Ekihiro Seki
- Division of Digestive and Liver Diseases, Department of Medicine, Cedars-Sinai Medical Center, Los Angeles, California, USA
| | - Yu-Jui Yvonne Wan
- Department of Medical Pathology and Laboratory Medicine, UCD, Sacramento, California, USA
| | - Cheol Soo Choi
- Korea Mouse Metabolic Phenotyping Center, Lee Gil Ya Cancer and Diabetes Institute, Gachon University of Medicine and Science, Incheon, South Korea.,Endocrinology, Internal Medicine, Gachon University Gil Medical Center, Incheon, South Korea
| | - Sang Geon Kim
- College of Pharmacy and Research Institute of Pharmaceutical Sciences, Seoul National University, Seoul, South Korea
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Finley J. Cellular stress and AMPK activation as a common mechanism of action linking the effects of metformin and diverse compounds that alleviate accelerated aging defects in Hutchinson-Gilford progeria syndrome. Med Hypotheses 2018; 118:151-162. [PMID: 30037605 DOI: 10.1016/j.mehy.2018.06.029] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2018] [Revised: 06/13/2018] [Accepted: 06/27/2018] [Indexed: 12/19/2022]
Abstract
Hutchinson-Gilford progeria syndrome (HGPS) is a rare genetic disorder characterized by an accelerated aging phenotype that typically leads to death via stroke or myocardial infarction at approximately 14.6 years of age. Most cases of HGPS have been linked to the extensive use of a cryptic splice donor site located in the LMNA gene due to a de novo mutation, generating a truncated and toxic protein known as progerin. Progerin accumulation in the nuclear membrane and within the nucleus distorts the nuclear architecture and negatively effects nuclear processes including DNA replication and repair, leading to accelerated cellular aging and premature senescence. The serine-arginine rich splicing factor SRSF1 (also known as ASF/SF2) has recently been shown to modulate alternative splicing of the LMNA gene, with SRSF1 inhibition significantly reducing progerin at both the mRNA and protein levels. In 2014, we hypothesized for the first time that compounds including metformin that induce activation of AMP-activated protein kinase (AMPK), a master metabolic regulator activated by cellular stress (e.g. increases in intracellular calcium, reactive oxygen species, and/or an AMP(ADP)/ATP ratio increase, etc.), will beneficially alter gene splicing in progeria cells by inhibiting SRSF1, thus lowering progerin levels and altering the LMNA pre-mRNA splicing ratio. Recent evidence has substantiated this hypothesis, with metformin significantly reducing the mRNA and protein levels of both SRSF1 and progerin, activating AMPK, and alleviating pathological defects in HGPS cells. Metformin has also recently been shown to beneficially alter gene splicing in normal humans. Interestingly, several chemically distinct compounds, including rapamycin, methylene blue, all-trans retinoic acid, MG132, 1α,25-dihydroxyvitamin D3, sulforaphane, and oltipraz have each been shown to alleviate accelerated aging defects in patient-derived HGPS cells. Each of these compounds has also been independently shown to induce AMPK activation. Because these compounds improve accelerated aging defects in HGPS cells either by enhancing mitochondrial functionality, increasing Nrf2 activity, inducing autophagy, or by altering gene splicing and because AMPK activation beneficially modulates each of the aforementioned processes, it is our hypothesis that cellular stress-induced AMPK activation represents an indirect yet common mechanism of action linking such chemically diverse compounds with the beneficial effects of those compounds observed in HGPS cells. As normal humans also produce progerin at much lower levels through a similar mechanism, compounds that safely induce AMPK activation may have wide-ranging implications for both normal and pathological aging.
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Bis-(5-substituted-2-thiono-1,3,5-thiadiazinan-3-yl) butane as a scaffold of anti-proliferative activity, blended by a multicomponent process. Med Chem Res 2018. [DOI: 10.1007/s00044-018-2133-9] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
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Kim W, Kim BG, Lee JS, Lee CK, Yeon JE, Chang MS, Kim JH, Kim H, Yi S, Lee J, Cho JY, Kim SG, Lee JH, Kim YJ. Randomised clinical trial: the efficacy and safety of oltipraz, a liver X receptor alpha-inhibitory dithiolethione in patients with non-alcoholic fatty liver disease. Aliment Pharmacol Ther 2017; 45:1073-1083. [PMID: 28225186 DOI: 10.1111/apt.13981] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/19/2016] [Revised: 05/31/2016] [Accepted: 01/22/2017] [Indexed: 12/11/2022]
Abstract
BACKGROUND Oltipraz is a synthetic dithiolethione with an antisteatotic effect by inhibiting the activity of liver X receptor alpha (LXR-α). Recent studies demonstrated the disruptive role of oltipraz on LXR-α-dependent lipogenesis in hepatocytes and a high-fat diet mouse model. AIM To evaluate the efficacy and safety of oltipraz for reducing liver fat in subjects with non-alcoholic fatty liver disease (NAFLD). METHODS We performed a multicentre, double-blind, placebo-controlled, phase II study. Subjects with a liver fat >20% and hypertransaminasemia were randomised to the three groups: placebo (n = 22), 30 mg of oltipraz (n = 22) or 60 mg of oltipraz (n = 24) twice daily for 24 weeks. Changes in the liver fat from baseline to 24 weeks quantified using magnetic resonance spectroscopy were the primary outcome. RESULTS Compared with the placebo group (-3.2 ± 11.1%), absolute changes in the liver fat content increased in a dose-dependent manner: -7.7 ± 7.0% and -13.9 ± 10.7% for the low-dose and high-dose groups (P = 0.13 and P < 0.01). Per cent reduction in the liver fat content was also significantly greater in the high-dose group than in the placebo group (-34.6 ± 29.4% vs. -0.6 ± 62.9%, P = 0.046). Body mass indices (-1.0 ± 0.9% vs. -0.5 ± 1.4%, P = 0.04) significantly decreased in the high-dose group compared to the placebo group. However, absolute changes in insulin resistance, liver enzymes, lipids and cytokines were not significantly different among groups. The incidence of adverse events was comparable among groups. CONCLUSIONS Twenty-four-week oltipraz treatment significantly reduced the liver fat content in patients with NAFLD. Clinicaltrials.gov (NCT01373554).
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Zhang Z, Zhou S, Jiang X, Wang YH, Li F, Wang YG, Zheng Y, Cai L. The role of the Nrf2/Keap1 pathway in obesity and metabolic syndrome. Rev Endocr Metab Disord 2015; 16:35-45. [PMID: 25540093 DOI: 10.1007/s11154-014-9305-9] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Nuclear factor erythroid 2 related factor 2 (Nrf2) is a key regulator of antioxidant signaling that may prevent the development of metabolic syndrome and related cardiovascular diseases. However, emerging evidence shows that lack of Nrf2 could ameliorate insulin resistance, adipogenesis and adipocyte differentiation. Consistent with this, overexpression of Nrf2 gene could also cause insulin resistance under certain conditions. Furthermore, an increasing number of studies indicate that redox balance can be a critical element that contributes to the contradictory effects of Nrf2 on insulin sensitivity and resistance. Reactive oxygen species can promote normal insulin-mediated signal transduction under physiological conditions but also induce insulin resistance under certain pathological conditions. Therefore, the contradictory effects of Nrf2 on insulin signaling pathways may be related to its regulation of redox homeostasis. This review attempts to summarize the latest developments in our understanding of the mechanisms of Nrf2-mediated signaling and its role in the modulation of metabolic homeostasis.
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Affiliation(s)
- Zhiguo Zhang
- Departments of Cardiovascular Disorders, Gerontology & Radiation Oncology at the First Hospital, Jilin University, Changchun, 130021, China
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Jayanthy G, Subramanian S. RA abrogates hepatic gluconeogenesis and insulin resistance by enhancing IRS-1 and AMPK signalling in experimental type 2 diabetes. RSC Adv 2015. [DOI: 10.1039/c5ra04605j] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
RA abrogates hyperglycemia and insulin resistance, the primary features of type 2 diabetes (T2DM).
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Affiliation(s)
- G. Jayanthy
- Department of Biochemistry
- University of Madras
- Guindy Campus
- Chennai
- India
| | - S. Subramanian
- Department of Biochemistry
- University of Madras
- Guindy Campus
- Chennai
- India
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SIRT1 activation by methylene blue, a repurposed drug, leads to AMPK-mediated inhibition of steatosis and steatohepatitis. Eur J Pharmacol 2014; 727:115-24. [PMID: 24486702 DOI: 10.1016/j.ejphar.2014.01.035] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2013] [Revised: 01/13/2014] [Accepted: 01/22/2014] [Indexed: 02/08/2023]
Abstract
Sirtuins maintain energy balance. Particularly, sirtuin 1 (SIRT1) activation mimics calorie restriction and nutrient utilization. However, no medications are available for the up-regulation of SIRT1. Methylene blue (MB) had been in clinical trials for the treatment of neurological diseases. This study investigated the effect of MB on sirtuin expression in association with the treatment of steatosis and steatohepatitis, and explored the underlying basis. The effects of MB on mitochondrial function, molecular markers, pharmacokinetics, and histopathology were assessed using hepatocyte and/or mouse models. Immunoblotting, PCR and reporter assays were done for molecular experiments. After oral administration, MB was well distributed in the liver. MB treatment increased NAD(+)/NADH ratio in hepatocytes. Of the major forms, MB treatment up-regulated SIRT1, and thereby decreased PGC-1α acetylation. Consistently, hepatic mitochondrial DNA contents and oxygen consumption rates were enhanced. MB treatment also notably activated AMPK, CPT-1 and PPARα: the AMPK activation relied on SIRT1. Activation of LXRα and the induction of SREBP-1c and its target genes by T0901317 were diminished by MB. In addition, MB treatment antagonized the ability of palmitate to acetylate PGC-1α, and increase SERBP-1c, FAS, and ACC levels. In mice fed on a high-fat diet for 8 weeks, MB treatment inhibited excessive hepatic fat accumulation and steatohepatitis. The ability of MB to activate SIRT1 promotes mitochondrial biogenesis and oxygen consumption and activates AMPK, contributing to anti-lipogenesis in the liver. Our results provide new information on the potential use of MB for the treatment of steatosis and steatohepatitis.
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