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Liu X, Wu S, Peng Y, Gao L, Huang X, Deng R, Lu J. Delineation of renal protein profiles in aristolochic acid I-induced nephrotoxicity in mice by label-free quantitative proteomics. Front Pharmacol 2024; 15:1341854. [PMID: 38783935 PMCID: PMC11111959 DOI: 10.3389/fphar.2024.1341854] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2023] [Accepted: 04/15/2024] [Indexed: 05/25/2024] Open
Abstract
Introduction: Aristolochic acid nephropathy (AAN) is a kidney injury syndrome caused by aristolochic acids exposure. Our study used label-free quantitative proteomics to delineate renal protein profiles and identify key proteins after exposure to different doses of aristolochic acid I (AAI). Methods: Male C57BL/6 mice received AAI (1.25 mg/kg/d, 2.5 mg/kg/d, or 5 mg/kg/d) or vehicle for 5 days. Results and discussion: The results showed that AAI induced dose-dependent nephrotoxicity. Differences in renal protein profiles between the control and AAI groups increased with AAI dose. Comparing the control with the low-, medium-, and high-dose AAI groups, we found 58, 210, and 271 differentially expressed proteins, respectively. Furthermore, protein-protein interaction network analysis identified acyl-CoA synthetase medium-chain family member 3 (Acsm3), cytochrome P450 family 2 subfamily E member 1 (Cyp2e1), microsomal glutathione S-transferase 1 (Mgst1), and fetuin B (Fetub) as the key proteins. Proteomics revealed that AAI decreased Acsm3 and Cyp2e1 while increasing Mgst1 and Fetub expression in mice kidneys, which was further confirmed by Western blotting. Collectively, in AAI-induced nephrotoxicity, renal protein profiles were dysregulated and exacerbated with increasing AAI dose. Acsm3, Cyp2e1, Mgst1, and Fetub may be the potential therapeutic targets for AAN.
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Affiliation(s)
- Xinhui Liu
- Department of Nephrology, Shenzhen Traditional Chinese Medicine Hospital, Guangzhou University of Chinese Medicine, Shenzhen, Guangdong, China
| | - Shanshan Wu
- Department of Nephrology, Shenzhen Traditional Chinese Medicine Hospital, Guangzhou University of Chinese Medicine, Shenzhen, Guangdong, China
- The Fourth Clinical Medical College, Guangzhou University of Chinese Medicine, Shenzhen, Guangdong, China
| | - Yu Peng
- Department of Nephrology, Shenzhen Traditional Chinese Medicine Hospital, Guangzhou University of Chinese Medicine, Shenzhen, Guangdong, China
- The Fourth Clinical Medical College, Guangzhou University of Chinese Medicine, Shenzhen, Guangdong, China
| | - Liwen Gao
- Department of Nephrology, Shenzhen Traditional Chinese Medicine Hospital, Guangzhou University of Chinese Medicine, Shenzhen, Guangdong, China
- The Fourth Clinical Medical College, Guangzhou University of Chinese Medicine, Shenzhen, Guangdong, China
| | - Xi Huang
- Department of Nephrology, Shenzhen Traditional Chinese Medicine Hospital, Guangzhou University of Chinese Medicine, Shenzhen, Guangdong, China
- The Fourth Clinical Medical College, Guangzhou University of Chinese Medicine, Shenzhen, Guangdong, China
| | - Ruyu Deng
- Department of Nephrology, Shenzhen Traditional Chinese Medicine Hospital, Guangzhou University of Chinese Medicine, Shenzhen, Guangdong, China
- Shenzhen Traditional Chinese Medicine Hospital Affiliated to Nanjing University of Chinese Medicine, Shenzhen, Guangdong, China
| | - Jiandong Lu
- Department of Nephrology, Shenzhen Traditional Chinese Medicine Hospital, Guangzhou University of Chinese Medicine, Shenzhen, Guangdong, China
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Kim DH, Lee S, Noh SG, Lee J, Chung HY. FoxO6-mediated ApoC3 upregulation promotes hepatic steatosis and hyperlipidemia in aged rats fed a high-fat diet. Aging (Albany NY) 2024; 16:4095-4115. [PMID: 38441531 PMCID: PMC10968681 DOI: 10.18632/aging.205610] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Accepted: 01/24/2024] [Indexed: 03/22/2024]
Abstract
FoxO6, an identified factor, induces hyperlipidemia and hepatic steatosis during aging by activating hepatic lipoprotein secretion and lipogenesis leading to increased ApoC3 concentrations in the bloodstream. However, the intricate mechanisms underlying hepatic steatosis induced by elevated FoxO6 under hyperglycemic conditions remain intricate and require further elucidation. In order to delineate the regulatory pathway involving ApoC3 controlled by FoxO6 and its resultant functional impacts, we employed a spectrum of models including liver cell cultures, aged rats subjected to HFD, transgenic mice overexpressing FoxO6 (FoxO6-Tg), and FoxO6 knockout mice (FoxO6-KO). Our findings indicate that FoxO6 triggered ApoC3-driven lipid accumulation in the livers of aged rats on an HFD and in FoxO6-Tg, consequently leading to hepatic steatosis and hyperglycemia. Conversely, the absence of FoxO6 attenuated the expression of genes involved in lipogenesis, resulting in diminished hepatic lipid accumulation and mitigated hyperlipidemia in murine models. Additionally, the upregulation of FoxO6 due to elevated glucose levels led to increased ApoC3 expression, consequently instigating cellular triglyceride mediated lipid accumulation. The transcriptional activation of FoxO6 induced by both the HFD and high glucose levels resulted in hepatic steatosis by upregulating ApoC3 and genes associated with gluconeogenesis in aged rats and liver cell cultures. Our conclusions indicate that the upregulation of ApoC3 by FoxO6 promotes the development of hyperlipidemia, hyperglycemia, and hepatic steatosis in vivo, and in vitro. Taken together, our findings underscore the significance of FoxO6 in driving hyperlipidemia and hepatic steatosis specifically under hyperglycemic states by enhancing the expression of ApoC3 in aged rats.
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Affiliation(s)
- Dae Hyun Kim
- Department of Food Science and Technology, College of Natural Resources and Life Science, Pusan National University, Miryang-si, Gyeongsangnam-do 50463, Republic of Korea
| | - Seulah Lee
- Department of Pharmacy, Research Institute for Drug Development, College of Pharmacy, Pusan National University, Geumjeong-gu, Busan 46241, Republic of Korea
| | - Sang Gyun Noh
- Department of Pharmacy, Research Institute for Drug Development, College of Pharmacy, Pusan National University, Geumjeong-gu, Busan 46241, Republic of Korea
| | - Jaewon Lee
- Department of Pharmacy, Research Institute for Drug Development, College of Pharmacy, Pusan National University, Geumjeong-gu, Busan 46241, Republic of Korea
| | - Hae Young Chung
- Department of Pharmacy, Research Institute for Drug Development, College of Pharmacy, Pusan National University, Geumjeong-gu, Busan 46241, Republic of Korea
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3
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Wuttiputhanun T, Udomkarnjananun S, Hanprathet N, Jiamjarasrangsi W, Townamchai N, Avihingsanon Y, Katavetin P. Metabolic effects of kidney donation: A Bayesian analysis of matched cohorts. Nephrology (Carlton) 2023; 28:148-153. [PMID: 36515383 DOI: 10.1111/nep.14136] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2022] [Revised: 12/04/2022] [Accepted: 12/11/2022] [Indexed: 12/15/2022]
Abstract
The kidney is a notable site of glycolysis, gluconeogenesis, and fatty acid oxidation. Loss of a kidney after kidney donation might, therefore, affect the glucose and lipid metabolism of the donors. This matched cohort study investigated the effect of nephrectomy on glucose and lipid metabolisms using Bayesian hypothesis testing. There were 77 pairs of matched donor-control pairs in the present study. Clinical and laboratory data of the participants, at baseline and 1-year, were extracted from electronic medical records. Comparisons between donor and control groups were performed using the Bayesian independent samples t-test or Bayesian Mann-Whitney test. The Bayes Factor for alternative hypothesis over null hypothesis (BF10 ) was used to compare the two competing hypotheses. The BF10 of 3 or more was considered evidence for the alternative hypothesis. Comparing changes from baseline to 1-year between donors and controls, the BF10 of triglycerides, high-density lipoprotein cholesterol (HDL-C), triglyceride-glucose (TyG) index of insulin resistance, and estimated glomerular filtration rate (eGFR) were 7.95, 3.96, 30.13, and 1.32 x 1041 , respectively signifying that the change of these variables in the donors differed from those in the controls (alternative hypothesis). Triglyceride, HDL-C, and TyG index of the donors increased more than those of the controls while eGFR of the donor decreased more than that of the controls. Our data suggest that triglycerides and insulin resistance increase after donor nephrectomy. Kidney donors should be informed about these metabolic changes and should adhere to lifestyle recommendations that may mitigate insulin resistance.
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Affiliation(s)
- Thunyatorn Wuttiputhanun
- Division of Nephrology, Department of Medicine, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Bangkok, Thailand
| | - Suwasin Udomkarnjananun
- Division of Nephrology, Department of Medicine, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Bangkok, Thailand.,Excellence Center for Solid Organ Transplantation, King Chulalongkorn Memorial Hospital, Bangkok, Thailand.,Renal Immunology and Renal Transplant Research Unit, Department of Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Nitt Hanprathet
- Department of Preventive and Social Medicine, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Bangkok, Thailand
| | - Wiroj Jiamjarasrangsi
- Department of Preventive and Social Medicine, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Bangkok, Thailand
| | - Nattavudh Townamchai
- Division of Nephrology, Department of Medicine, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Bangkok, Thailand.,Excellence Center for Solid Organ Transplantation, King Chulalongkorn Memorial Hospital, Bangkok, Thailand.,Renal Immunology and Renal Transplant Research Unit, Department of Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Yingyos Avihingsanon
- Division of Nephrology, Department of Medicine, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Bangkok, Thailand
| | - Pisut Katavetin
- Division of Nephrology, Department of Medicine, Faculty of Medicine, Chulalongkorn University and King Chulalongkorn Memorial Hospital, Bangkok, Thailand
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4
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Ye Z, Zhang Y, Huang N, Chen S, Wu X, Li L. Immune repertoire and evolutionary trajectory analysis in the development of diabetic nephropathy. Front Immunol 2022; 13:1006137. [PMID: 36211355 PMCID: PMC9537376 DOI: 10.3389/fimmu.2022.1006137] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2022] [Accepted: 09/05/2022] [Indexed: 11/13/2022] Open
Abstract
Diabetic nephropathy (DN) is the leading cause of death and the greatest risk to the lives of people with advanced diabetes. Yet, the molecular mechanisms underlying its development and progression remain unknown. In this research, we studied the primary pathways driving DN using transcriptome sequencing and immune repertoire analysis. Firstly, we found that the diversity and abundance of the immune repertoire in late DN were significantly increased, while there was no significant change in early DN. Furthermore, B cell-mediated antibody responses may be the leading cause of DN progression. By analyzing master regulators, we found the key DN-driving transcription factors. In the late stage of DN, immune cells, fibroblasts, and epithelial cells were abundant, but other stromal cells were few. Early DN kidneys had a higher tissue stemness score than normal and advanced DN kidneys. We showed that DN progression involves proximal tubular metabolic reprogramming and stemness restoration using Monocle3. Through WGCNA, we found that co-expression modules that regulate DN progression and immune repertoire diversity mainly regulate immune-related signaling pathways. In addition, we also found that early DN had apparent activation of immune-related signaling pathways mainly enriched in immune cells. Finally, we found that activation of fibroblasts is typical of early DN. These results provide a research basis for further exploring the molecular biology and cellular mechanisms of the occurrence and development of DN and provide a theoretical basis for the prevention and treatment of DN.
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Affiliation(s)
- Zheng Ye
- Department of Endocrinology, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, China
- State Key Laboratory of Bioelectronics, School of Biological Science and Medical Engineering, Southeast University, Nanjing, China
| | - Yidi Zhang
- Department of Endocrinology, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, China
| | - Nan Huang
- Department of Endocrinology, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, China
| | - Shen Chen
- Department of Endocrinology, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, China
| | - Xiaodong Wu
- Department of Endocrinology, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, China
| | - Ling Li
- Department of Endocrinology, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, China
- Institute of Glucose and Lipid Metabolism, Southeast University, Nanjing, China
- Department of Clinical Science and Research, Zhongda Hospital, School of Medicine, Southeast University, Nanjing, China
- *Correspondence: Ling Li,
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5
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Li N, Liu X, Lei Y, Wang B, Li Z. Melatonin Ameliorates Cisplatin-Induced Renal Tubular Epithelial Cell Damage through PPARα/FAO Regulation. Chem Res Toxicol 2022; 35:1503-1511. [PMID: 36006825 DOI: 10.1021/acs.chemrestox.2c00121] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Previous studies revealed that melatonin ameliorated acute renal injury induced by cisplatin, but the mechanisms remain unclear. Peroxidase proliferative receptor α (PPARα) is considered the major regulator of fatty acid oxidation (FAO), which is an important source of energy for renal tubular epithelial cells. In this study, the aim was to investigate the role of melatonin in cisplatin-induced NRK-52E (rat renal tubular epithelial cell line) cell damage and the underlying mechanisms. We established a cisplatin-stimulated NRK-52E model in vitro. We assessed the levels of apoptotic proteins, including caspase-3, caspase-9, and B-cell lymphoma 2-associated X protein (Bax), as well as PPARα and FAO-related genes (Acadm, Acat1, Acsm2, Acsm3, PGC-1α, Pecr, Bdh2, and Echs1). Furthermore, we detected the effects of miR-21 and PPARα antagonist on the above indicators. We found that melatonin reduced the protein expression levels of caspase-3, caspase-9, and Bax, and increased the expression levels of the PPARα gene and protein and PPARα activity, as well as FAO-related genes, in NRK-52E cells. However, miR-21 mimics and PPARα antagonists partially antagonized the above effects of melatonin. Our data indicated that melatonin could alleviate cisplatin-induced cell damage through the upregulation of PPARα/FAO.
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Affiliation(s)
- Ningning Li
- Department of Pathology, Henan Medical College, Zhengzhou 451191, China
| | - Xianghua Liu
- Academy of Chinese Medical Sciences, Henan University of Chinese Medicine, Zhengzhou 450046, China
| | - Yanfei Lei
- Department of Pathology, Henan Medical College, Zhengzhou 451191, China
| | - Baoying Wang
- Academy of Chinese Medical Sciences, Henan University of Chinese Medicine, Zhengzhou 450046, China
| | - Zhenzhen Li
- Medical Research Center, The First Affiliated Hospital of Zhengzhou University, Zhengzhou 450052, China
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6
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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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7
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Ito M, Gurumani MZ, Merscher S, Fornoni A. Glucose- and Non-Glucose-Induced Mitochondrial Dysfunction in Diabetic Kidney Disease. Biomolecules 2022; 12:biom12030351. [PMID: 35327540 PMCID: PMC8945149 DOI: 10.3390/biom12030351] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2022] [Revised: 02/21/2022] [Accepted: 02/21/2022] [Indexed: 12/20/2022] Open
Abstract
Mitochondrial dysfunction plays an important role in the pathogenesis and progression of diabetic kidney disease (DKD). In this review, we will discuss mitochondrial dysfunction observed in preclinical models of DKD as well as in clinical DKD with a focus on oxidative phosphorylation (OXPHOS), mitochondrial reactive oxygen species (mtROS), biogenesis, fission and fusion, mitophagy and urinary mitochondrial biomarkers. Both glucose- and non-glucose-induced mitochondrial dysfunction will be discussed. In terms of glucose-induced mitochondrial dysfunction, the energetic shift from OXPHOS to aerobic glycolysis, called the Warburg effect, occurs and the resulting toxic intermediates of glucose metabolism contribute to DKD-induced injury. In terms of non-glucose-induced mitochondrial dysfunction, we will review the roles of lipotoxicity, hypoxia and vasoactive pathways, including endothelin-1 (Edn1)/Edn1 receptor type A signaling pathways. Although the relative contribution of each of these pathways to DKD remains unclear, the goal of this review is to highlight the complexity of mitochondrial dysfunction in DKD and to discuss how markers of mitochondrial dysfunction could help us stratify patients at risk for DKD.
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Affiliation(s)
| | | | - Sandra Merscher
- Correspondence: (S.M.); (A.F.); Tel.: +1-305-243-6567 (S.M.); +1-305-243-7745 (A.F.)
| | - Alessia Fornoni
- Correspondence: (S.M.); (A.F.); Tel.: +1-305-243-6567 (S.M.); +1-305-243-7745 (A.F.)
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8
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Li J, Yang Y, Li Q, Wei S, Zhou Y, Yu W, Xue L, Zhou L, Shen L, Lu G, Chen L, Tao S. STAT6 contributes to renal fibrosis by modulating PPARα-mediated tubular fatty acid oxidation. Cell Death Dis 2022; 13:66. [PMID: 35046382 PMCID: PMC8770798 DOI: 10.1038/s41419-022-04515-3] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2021] [Revised: 12/14/2021] [Accepted: 01/10/2022] [Indexed: 12/13/2022]
Abstract
Lipid metabolism, especially fatty acid oxidation (FAO) dysfunction, is a major driver of renal fibrosis; however, the detailed regulatory mechanisms involved remain unclear. In this study, we showed that there existed an association between the signal transducer and activator of transcription 6 (STAT6) and tubular lipid metabolism in fibrotic kidneys. Specifically, STAT6 was activated along with the accumulation of lipids via the downregulation of FAO-related genes when mice were subjected to unilateral ureteral obstruction (UUO) or high-fat diet challenge. Tubular-specific depletion, or pharmacologic inhibitor of Stat6 in mice, and Stat6 knockdown in cultured tubular cells attenuated lipid accumulation and renal fibrosis by enhancing FAO. Mechanistically, STAT6 transcriptionally inhibited the expression of PPARα and its FAO-related target genes through a sis-inducible element located in the promoter region of the protein. In conclusion, our study demonstrates the mechanistic details of STAT6-mediated FAO dysregulation in the progression of renal fibrosis and provides a preclinical rationale for efforts to improve the management of renal fibrosis brought about by FAO dysregulation.
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Affiliation(s)
- Jianzhong Li
- Medical College of Soochow University, 199 Ren'ai Road, Suzhou, 215123, China
- Department of Nephrology, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu, 215006, China
| | - Youjing Yang
- School of Public Health, Medical College of Soochow University, 199 Ren'ai Road, Suzhou, 215123, China
| | - Qianmin Li
- School of Public Health, Medical College of Soochow University, 199 Ren'ai Road, Suzhou, 215123, China
| | - Shuhui Wei
- School of Public Health, Medical College of Soochow University, 199 Ren'ai Road, Suzhou, 215123, China
| | - Yujia Zhou
- School of Public Health, Medical College of Soochow University, 199 Ren'ai Road, Suzhou, 215123, China
| | - Wangjianfei Yu
- School of Public Health, Medical College of Soochow University, 199 Ren'ai Road, Suzhou, 215123, China
| | - Lian Xue
- School of Public Health, Medical College of Soochow University, 199 Ren'ai Road, Suzhou, 215123, China
| | - Ling Zhou
- Department of Nephrology, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu, 215006, China
| | - Lei Shen
- Department of Nephrology, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu, 215006, China
| | - Guoyuan Lu
- Department of Nephrology, The First Affiliated Hospital of Soochow University, Suzhou, Jiangsu, 215006, China
| | - Ling Chen
- School of Public Health, Medical College of Soochow University, 199 Ren'ai Road, Suzhou, 215123, China
| | - Shasha Tao
- Medical College of Soochow University, 199 Ren'ai Road, Suzhou, 215123, China.
- School of Public Health, Medical College of Soochow University, 199 Ren'ai Road, Suzhou, 215123, China.
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9
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Ahmad AA, Draves SO, Rosca M. Mitochondria in Diabetic Kidney Disease. Cells 2021; 10:cells10112945. [PMID: 34831168 PMCID: PMC8616075 DOI: 10.3390/cells10112945] [Citation(s) in RCA: 41] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2021] [Revised: 10/26/2021] [Accepted: 10/28/2021] [Indexed: 12/11/2022] Open
Abstract
Diabetic kidney disease (DKD) is the leading cause of end stage renal disease (ESRD) in the USA. The pathogenesis of DKD is multifactorial and involves activation of multiple signaling pathways with merging outcomes including thickening of the basement membrane, podocyte loss, mesangial expansion, tubular atrophy, and interstitial inflammation and fibrosis. The glomerulo-tubular balance and tubule-glomerular feedback support an increased glomerular filtration and tubular reabsorption, with the latter relying heavily on ATP and increasing the energy demand. There is evidence that alterations in mitochondrial bioenergetics in kidney cells lead to these pathologic changes and contribute to the progression of DKD towards ESRD. This review will focus on the dialogue between alterations in bioenergetics in glomerular and tubular cells and its role in the development of DKD. Alterations in energy substrate selection, electron transport chain, ATP generation, oxidative stress, redox status, protein posttranslational modifications, mitochondrial dynamics, and quality control will be discussed. Understanding the role of bioenergetics in the progression of diabetic DKD may provide novel therapeutic approaches to delay its progression to ESRD.
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10
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Bobulescu IA, Pop LM, Mani C, Turner K, Rivera C, Khatoon S, Kairamkonda S, Hannan R, Palle K. Renal Lipid Metabolism Abnormalities in Obesity and Clear Cell Renal Cell Carcinoma. Metabolites 2021; 11:608. [PMID: 34564424 PMCID: PMC8470169 DOI: 10.3390/metabo11090608] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2021] [Revised: 09/03/2021] [Accepted: 09/03/2021] [Indexed: 02/07/2023] Open
Abstract
Clear cell renal cell carcinoma is the most common and deadly type of cancer affecting the kidney, and is characterized histologically by large intracellular lipid deposits. These deposits are thought to result from lipid metabolic reprogramming occurring in tumor cells, but the exact mechanisms and implications of these metabolic alterations are incompletely understood. Obesity is an independent risk factor for clear cell renal cell carcinoma, and is also associated with lipid accumulation in noncancerous epithelial cells of the proximal tubule, where clear cell renal cell carcinoma originates. This article explores the potential link between obesity-associated renal lipid metabolic disturbances and lipid metabolic reprogramming in clear cell renal cell carcinoma, and discusses potential implications for future research.
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Affiliation(s)
- Ion Alexandru Bobulescu
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430-6540, USA; (C.M.); (K.T.); (C.R.); (S.K.); (S.K.); (K.P.)
- Department of Internal Medicine, Texas Tech University Health Sciences Center, Lubbock, TX 79430-6540, USA
| | - Laurentiu M. Pop
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX 79430-6540, USA; (L.M.P.); (R.H.)
| | - Chinnadurai Mani
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430-6540, USA; (C.M.); (K.T.); (C.R.); (S.K.); (S.K.); (K.P.)
| | - Kala Turner
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430-6540, USA; (C.M.); (K.T.); (C.R.); (S.K.); (S.K.); (K.P.)
| | - Christian Rivera
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430-6540, USA; (C.M.); (K.T.); (C.R.); (S.K.); (S.K.); (K.P.)
| | - Sabiha Khatoon
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430-6540, USA; (C.M.); (K.T.); (C.R.); (S.K.); (S.K.); (K.P.)
| | - Subash Kairamkonda
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430-6540, USA; (C.M.); (K.T.); (C.R.); (S.K.); (S.K.); (K.P.)
| | - Raquibul Hannan
- Department of Radiation Oncology, University of Texas Southwestern Medical Center, Dallas, TX 79430-6540, USA; (L.M.P.); (R.H.)
| | - Komaraiah Palle
- Department of Cell Biology and Biochemistry, Texas Tech University Health Sciences Center, Lubbock, TX 79430-6540, USA; (C.M.); (K.T.); (C.R.); (S.K.); (S.K.); (K.P.)
- Department of Surgery, Texas Tech University Health Sciences Center, Lubbock, TX 79430-6540, USA
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11
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Li W, Duan A, Xing Y, Xu L, Yang J. Transcription-Based Multidimensional Regulation of Fatty Acid Metabolism by HIF1α in Renal Tubules. Front Cell Dev Biol 2021; 9:690079. [PMID: 34277635 PMCID: PMC8283824 DOI: 10.3389/fcell.2021.690079] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 05/26/2021] [Indexed: 12/12/2022] Open
Abstract
Lipid metabolism plays a basic role in renal physiology, especially in tubules. Hypoxia and hypoxia-induced factor (HIF) activation are common in renal diseases; however, the relationship between HIF and tubular lipid metabolism is poorly understood. Using prolyl hydroxylase inhibitor roxadustat (FG-4592), we verified and further explored the relationship between sustained HIF1α activation and lipid accumulation in cultured tubular cells. A transcriptome and chromatin immunoprecipitation sequencing analysis revealed that HIF1α directly regulates the expression of a number of genes possibly affecting lipid metabolism, including those associated with mitochondrial function. HIF1α activation suppressed fatty acid (FA) mobilization from lipid droplets (LDs) and extracellular FA uptake. Moreover, HIF1α decreased FA oxidation and ATP production. A lipidomics analysis showed that FG-4592 caused strong triglyceride (TG) accumulation and increased some types of phospholipids with polyunsaturated fatty acyl (PUFA) chains, as well as several proinflammatory lipids. Nevertheless, the overall FA level was maintained. Thus, our study indicated that HIF1α reduced the FA supply and utilization and reconstructed the composition of lipids in tubules, which is likely a part of hypoxic adaptation but could also be involved in pathological processes in the kidney.
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Affiliation(s)
- Wenju Li
- National Clinical Research Center of Kidney Diseases, Jinling Hospital, Medical School of Nanjing University, Nanjing, China
| | - Aiping Duan
- National Clinical Research Center of Kidney Diseases, Jinling Hospital, Medical School of Nanjing University, Nanjing, China
| | - Yuexian Xing
- National Clinical Research Center of Kidney Diseases, Jinling Hospital, Medical School of Nanjing University, Nanjing, China
| | - Li Xu
- Department of Otorhinolaryngology-Head and Neck Surgery, Jinling Hospital, Medical School of Nanjing University, Nanjing, China
| | - Jingping Yang
- National Clinical Research Center of Kidney Diseases, Jinling Hospital, Medical School of Nanjing University, Nanjing, China.,Medical School of Nanjing University, Nanjing, China
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12
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Popescu RG, Bulgaru C, Untea A, Vlassa M, Filip M, Hermenean A, Marin D, Țăranu I, Georgescu SE, Dinischiotu A. The Effectiveness of Dietary Byproduct Antioxidants on Induced CYP Genes Expression and Histological Alteration in Piglets Liver and Kidney Fed with Aflatoxin B1 and Ochratoxin A. Toxins (Basel) 2021; 13:148. [PMID: 33671978 PMCID: PMC7919288 DOI: 10.3390/toxins13020148] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2021] [Revised: 02/12/2021] [Accepted: 02/13/2021] [Indexed: 02/07/2023] Open
Abstract
The purpose of this study was to investigate the potential of a byproduct mixture derived from grapeseed and sea buckthorn oil industry to mitigate the harmful damage produced by ochratoxin A and aflatoxin B1 at hepatic and renal level in piglets after weaning. Forty cross-bred TOPIGS-40 hybrid piglets after weaning were assigned to three experimental groups (E1, E2, E3) and one control group (C), and fed with experimental diets for 30 days. The basal diet was served as a control and contained normal compound feed for starter piglets without mycotoxins. The experimental groups were fed as follows: E1-basal diet plus a mixture (1:1) of two byproducts (grapeseed and sea buckthorn meal); E2-the basal diet experimentally contaminated with mycotoxins (479 ppb OTA and 62ppb AFB1); and E3-basal diet containing 5% of the mixture (1:1) of grapeseed and sea buckthorn meal and contaminated with the mix of OTA and AFB1. After 4 weeks, the animals were slaughtered, and tissue samples were taken from liver and kidney in order to perform gene expression and histological analysis. The gene expression analysis showed that when weaned piglets were fed with contaminated diet, the expression of most analyzed genes was downregulated. Among the CYP450 family, CYP1A2 was the gene with the highest downregulation. According to these results, in liver, we found that mycotoxins induced histomorphological alterations in liver and kidney and had an effect on the expression level of CYP1A2, CYP2A19, CYP2E1, and CYP3A29, but we did not detect important changes in the expression level of CY4A24, MRP2 and GSTA1 genes.
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Affiliation(s)
- Roua Gabriela Popescu
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Bucharest, Splaiul Independentei No. 91–95, 050095 Bucharest, Romania; (R.G.P.); (A.D.)
| | - Cristina Bulgaru
- Laboratory of Animal Biology, National Institute for Research and Development for Biology and Animal Nutrition, Calea Bucuresti No. 1, Balotesti, 077015 Ilfov, Romania; (C.B.); (A.U.); (D.M.)
| | - Arabela Untea
- Laboratory of Animal Biology, National Institute for Research and Development for Biology and Animal Nutrition, Calea Bucuresti No. 1, Balotesti, 077015 Ilfov, Romania; (C.B.); (A.U.); (D.M.)
| | - Mihaela Vlassa
- Raluca Ripan Institute for Research in Chemistry, Babeş Bolyai University, 30 Fântânele Street, 400294 Cluj-Napoca, Romania; (M.V.); (M.F.)
| | - Miuta Filip
- Raluca Ripan Institute for Research in Chemistry, Babeş Bolyai University, 30 Fântânele Street, 400294 Cluj-Napoca, Romania; (M.V.); (M.F.)
| | - Anca Hermenean
- “Aurel Ardelean” Institute of Life Sciences, Vasile Godis Western University of Arad, Rebreanu 86, 310414 Arad, Romania;
| | - Daniela Marin
- Laboratory of Animal Biology, National Institute for Research and Development for Biology and Animal Nutrition, Calea Bucuresti No. 1, Balotesti, 077015 Ilfov, Romania; (C.B.); (A.U.); (D.M.)
| | - Ionelia Țăranu
- Laboratory of Animal Biology, National Institute for Research and Development for Biology and Animal Nutrition, Calea Bucuresti No. 1, Balotesti, 077015 Ilfov, Romania; (C.B.); (A.U.); (D.M.)
| | - Sergiu Emil Georgescu
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Bucharest, Splaiul Independentei No. 91–95, 050095 Bucharest, Romania; (R.G.P.); (A.D.)
| | - Anca Dinischiotu
- Department of Biochemistry and Molecular Biology, Faculty of Biology, University of Bucharest, Splaiul Independentei No. 91–95, 050095 Bucharest, Romania; (R.G.P.); (A.D.)
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13
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Dimitriadis GD, Maratou E, Kountouri A, Board M, Lambadiari V. Regulation of Postabsorptive and Postprandial Glucose Metabolism by Insulin-Dependent and Insulin-Independent Mechanisms: An Integrative Approach. Nutrients 2021; 13:E159. [PMID: 33419065 PMCID: PMC7825450 DOI: 10.3390/nu13010159] [Citation(s) in RCA: 72] [Impact Index Per Article: 24.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2020] [Revised: 12/18/2020] [Accepted: 12/24/2020] [Indexed: 12/18/2022] Open
Abstract
Glucose levels in blood must be constantly maintained within a tight physiological range to sustain anabolism. Insulin regulates glucose homeostasis via its effects on glucose production from the liver and kidneys and glucose disposal in peripheral tissues (mainly skeletal muscle). Blood levels of glucose are regulated simultaneously by insulin-mediated rates of glucose production from the liver (and kidneys) and removal from muscle; adipose tissue is a key partner in this scenario, providing nonesterified fatty acids (NEFA) as an alternative fuel for skeletal muscle and liver when blood glucose levels are depleted. During sleep at night, the gradual development of insulin resistance, due to growth hormone and cortisol surges, ensures that blood glucose levels will be maintained within normal levels by: (a) switching from glucose to NEFA oxidation in muscle; (b) modulating glucose production from the liver/kidneys. After meals, several mechanisms (sequence/composition of meals, gastric emptying/intestinal glucose absorption, gastrointestinal hormones, hyperglycemia mass action effects, insulin/glucagon secretion/action, de novo lipogenesis and glucose disposal) operate in concert for optimal regulation of postprandial glucose fluctuations. The contribution of the liver in postprandial glucose homeostasis is critical. The liver is preferentially used to dispose over 50% of the ingested glucose and restrict the acute increases of glucose and insulin in the bloodstream after meals, thus protecting the circulation and tissues from the adverse effects of marked hyperglycemia and hyperinsulinemia.
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Affiliation(s)
- George D. Dimitriadis
- Sector of Medicine, Medical School, National and Kapodistrian University of Athens, 15772 Athens, Greece
| | - Eirini Maratou
- Department of Clinical Biochemistry, Medical School, National and Kapodistrian University of Athens, 15772 Athens, Greece;
- Department of Clinical Biochemistry, Medical School, “Attikon” University Hospital, Rimini 1, 12462 Chaidari, Greece
| | - Aikaterini Kountouri
- Research Institute and Diabetes Center, 2nd Department of Internal Medicine, “Attikon” University Hospital, 1 Rimini Street, 12542 Haidari, Greece; (A.K.); (V.L.)
| | - Mary Board
- St. Hilda’s College, University of Oxford, Cowley, Oxford OX4 1DY, UK;
| | - Vaia Lambadiari
- Research Institute and Diabetes Center, 2nd Department of Internal Medicine, “Attikon” University Hospital, 1 Rimini Street, 12542 Haidari, Greece; (A.K.); (V.L.)
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14
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Hypoxia-mediated regulation of mitochondrial transcription factors in renal epithelial cells: implications for hypertensive renal physiology. Hypertens Res 2020; 44:154-167. [PMID: 32917968 DOI: 10.1038/s41440-020-00539-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2020] [Revised: 07/19/2020] [Accepted: 07/23/2020] [Indexed: 02/07/2023]
Abstract
Kidneys have a high resting metabolic rate and low partial pressure of oxygen due to enhanced mitochondrial oxygen consumption and ATP production needed for active solute transport. Heightened mitochondrial activity leads to progressively increasing hypoxia from the renal cortex to the renal medulla. Renal hypoxia is prominent in hypertensive rats due to increased sodium reabsorption within the nephrons, which demands higher energy production by oxidative phosphorylation (OXPHOS). Consequently, spontaneously hypertensive rats (SHR) display greater oxygen deficiency (hypoxia) than normotensive Wistar Kyoto rats (WKY). Here, we sought to investigate the expression of key proteins for mitochondrial biogenesis in SHR and WKY, and study the regulation of mitochondrial transcription factors (mtTFs) under in vitro hypoxic conditions in renal epithelial cells. We report that renal expressions of hypoxia-inducible factor-1-alpha (HIF-1α), peroxisome proliferator-activated receptor-gamma coactivator-1-alpha (PGC-1α), mtTFs, and OXPHOS proteins are elevated in SHR compared to WKY. In addition, our experiments in cultured kidney cells demonstrate that acute hypoxia augments the expression of these genes. Furthermore, we show that the transcripts of HIF-1α and mtTFs are positively correlated in various human tissues. We reveal, for the first time to our knowledge, that HIF-1α transactivates mtTF genes by direct interaction with their promoters in rat kidney epithelial cells (NRK-52E) under acute hypoxia. Concomitant increases in the mitochondrial DNA and RNA, and OXPHOS proteins are observed. Taken together, this study suggests that hypoxia within the renal epithelial cells may enhance mitochondrial function to meet the energy demand in proximal tubular cells during prehypertensive stages in kidneys of young SHR.
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15
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Lin PH, Duann P. Dyslipidemia in Kidney Disorders: Perspectives on Mitochondria Homeostasis and Therapeutic Opportunities. Front Physiol 2020; 11:1050. [PMID: 33013450 PMCID: PMC7494972 DOI: 10.3389/fphys.2020.01050] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2020] [Accepted: 07/30/2020] [Indexed: 12/11/2022] Open
Abstract
To excrete body nitrogen waste and regulate electrolyte and fluid balance, the kidney has developed into an energy factory with only second to the heart in mitochondrial content in the body to meet the high-energy demand and regulate homeostasis. Energy supply from the renal mitochondria majorly depends on lipid metabolism, with programed enzyme systems in fatty acid β-oxidation and Krebs cycle. Renal mitochondria integrate several metabolic pathways, including AMPK/PGC-1α, PPARs, and CD36 signaling to maintain energy homeostasis for dynamic and static requirements. The pathobiology of several kidney disorders, including diabetic nephropathy, acute and chronic kidney injuries, has been primarily linked to impaired mitochondrial bioenergetics. Such homeostatic disruption in turn stimulates a pathological adaptation, with mitochondrial enzyme system reprograming possibly leading to dyslipidemia. However, this alteration, while rescuing oncotic pressure deficit secondary to albuminuria and dissipating edematous disorder, also imposes an ominous lipotoxic consequence. Reprograming of lipid metabolism in kidney injury is essential to preserve the integrity of kidney mitochondria, thereby preventing massive collateral damage including excessive autophagy and chronic inflammation. Here, we review dyslipidemia in kidney disorders and the most recent advances on targeting mitochondrial energy metabolism as a therapeutic strategy to restrict renal lipotoxicity, achieve salutary anti-edematous effects, and restore mitochondrial homeostasis.
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Affiliation(s)
- Pei-Hui Lin
- Department of Surgery, Davis Heart and Lung Research Institute, The Ohio State University, Columbus, OH, United States
| | - Pu Duann
- Research and Development, Salem Veteran Affairs Medical Center, Salem, VA, United States
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16
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Jin L, Ye H, Pan M, Chen Y, Ye B, Zheng Y, Huang W, Pan S, Shi Z, Zhang J. Kruppel-like factor 4 improves obesity-related nephropathy through increasing mitochondrial biogenesis and activities. J Cell Mol Med 2019; 24:1200-1207. [PMID: 31800161 PMCID: PMC6991690 DOI: 10.1111/jcmm.14628] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2019] [Revised: 06/03/2019] [Accepted: 06/19/2019] [Indexed: 12/24/2022] Open
Abstract
Obesity is positively linked to multiple metabolic complications including renal diseases. Several studies have demonstrated Kruppel‐like factor 4 (KLF4) participated in renal dysfunction and structural disorders in acute kidney injuries, but whether it affected the process of chronic kidney diseases was unknown. Therefore, present study was to disclose the role of renal KLF4 in dietary‐induced renal injuries and underlying mechanisms in obesity. Through utilizing high‐fat diet‐fed mice and human renal biopsies, we provided the physiological roles of KLF4 in protecting against obesity‐related nephropathy. Decreased levels of renal KLF4 were positively correlated with dietary‐induced renal dysfunction, including increased levels of creatinine and blood urea nitrogen. Overexpression of renal KLF4 suppressed inflammatory response in palmitic acid‐treated mouse endothelial cells. Furthermore, overexpressed KLF4 also attenuated dietary‐induced renal functional disorders, abnormal structural remodelling and inflammation. Mechanistically, KLF4 maintained renal mitochondrial biogenesis and activities to combat obesity‐induced mitochondrial dysfunction. In clinical renal biopsies and plasma, the renal Klf4 level was negatively associated with circulating levels of creatinine but positively associated with renal creatinine clearance. In conclusions, the present findings firstly supported that renal KLF4 played an important role in combating obesity‐related nephropathy, and KLF4/mitochondrial function partially determined the energy homeostasis in chronic kidney diseases.
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Affiliation(s)
- Lingwei Jin
- Department of Nephrology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Hanyang Ye
- Department of Nephrology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Min Pan
- Department of Nephrology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Yan Chen
- Department of Nephrology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Bairu Ye
- Department of Nephrology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Yu Zheng
- Department of Nephrology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Wenwen Huang
- Department of Nephrology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Shufang Pan
- Department of Nephrology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Zhen Shi
- Department of Nephrology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
| | - Jing Zhang
- Department of Nephrology, The Second Affiliated Hospital and Yuying Children's Hospital of Wenzhou Medical University, Wenzhou, China
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17
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Lee G, Uddin MJ, Kim Y, Ko M, Yu I, Ha H. PGC-1α, a potential therapeutic target against kidney aging. Aging Cell 2019; 18:e12994. [PMID: 31313501 PMCID: PMC6718532 DOI: 10.1111/acel.12994] [Citation(s) in RCA: 49] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Revised: 05/27/2019] [Accepted: 05/29/2019] [Indexed: 12/12/2022] Open
Abstract
Aging is defined as changes in an organism over time. The proportion of the aged population is markedly increasing worldwide. The kidney, as an essential organ with a high energy requirement, is one of the most susceptible organs to aging. It is involved in glucose metabolism via gluconeogenesis, glucose filtration and reabsorption, and glucose utilization. Proximal tubular epithelial cells (PTECs) depend on lipid metabolism to meet the high demand for ATP. Recent studies have shown that aging‐related kidney dysfunction is highly associated with metabolic changes in the kidney. Peroxisome proliferator‐activated receptor gamma coactivator‐1 alpha (PGC‐1α), a transcriptional coactivator, plays a major role in the regulation of mitochondrial biogenesis, peroxisomal biogenesis, and glucose and lipid metabolism. PGC‐1α is abundant in tissues, including kidney PTECs, which demand high energy. Many in vitro and in vivo studies have demonstrated that the activation of PGC‐1α by genetic or pharmacological intervention prevents telomere shortening and aging‐related changes in the skeletal muscle, heart, and brain. The activation of PGC‐1α can also prevent kidney dysfunction in various kidney diseases. Therefore, a better understanding of the effect of PGC‐1α activation in various organs on aging and kidney diseases may unveil a potential therapeutic strategy against kidney aging.
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Affiliation(s)
- Gayoung Lee
- Graduate School of Pharmaceutical Sciences Ewha Womans University Seoul Korea
- College of Pharmacy Ewha Womans University Seoul Korea
| | - Md Jamal Uddin
- Graduate School of Pharmaceutical Sciences Ewha Womans University Seoul Korea
- College of Pharmacy Ewha Womans University Seoul Korea
| | - Yoojeong Kim
- College of Pharmacy Ewha Womans University Seoul Korea
| | - Minji Ko
- College of Pharmacy Ewha Womans University Seoul Korea
| | - Inyoung Yu
- College of Pharmacy Ewha Womans University Seoul Korea
| | - Hunjoo Ha
- Graduate School of Pharmaceutical Sciences Ewha Womans University Seoul Korea
- College of Pharmacy Ewha Womans University Seoul Korea
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18
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Lipotoxicity in Kidney, Heart, and Skeletal Muscle Dysfunction. Nutrients 2019; 11:nu11071664. [PMID: 31330812 PMCID: PMC6682887 DOI: 10.3390/nu11071664] [Citation(s) in RCA: 84] [Impact Index Per Article: 16.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2019] [Revised: 07/01/2019] [Accepted: 07/17/2019] [Indexed: 12/19/2022] Open
Abstract
Dyslipidemia is a common nutritional and metabolic disorder in patients with chronic kidney disease. Accumulating evidence supports the hypothesis that prolonged metabolic imbalance of lipids leads to ectopic fat distribution in the peripheral organs (lipotoxicity), including the kidney, heart, and skeletal muscle, which accelerates peripheral inflammation and afflictions. Thus, lipotoxicity may partly explain progression of renal dysfunction and even extrarenal complications, including renal anemia, heart failure, and sarcopenia. Additionally, endoplasmic reticulum stress activated by the unfolded protein response pathway plays a pivotal role in lipotoxicity by modulating the expression of key enzymes in lipid synthesis and oxidation. Here, we review the molecular mechanisms underlying lipid deposition and resultant tissue damage in the kidney, heart, and skeletal muscle, with the goal of illuminating the nutritional aspects of these pathologies.
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19
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Yan Q, Song Y, Zhang L, Chen Z, Yang C, Liu S, Yuan X, Gao H, Ding G, Wang H. Autophagy activation contributes to lipid accumulation in tubular epithelial cells during kidney fibrosis. Cell Death Discov 2018; 4:2. [PMID: 30062051 PMCID: PMC6060103 DOI: 10.1038/s41420-018-0065-2] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2018] [Accepted: 05/14/2018] [Indexed: 12/25/2022] Open
Abstract
Sustained activation of autophagy and lipid accumulation in tubular epithelial cells (TECs) are both associated with the kidney fibrosis progression. Autophagy has been found involved in the lipid metabolism regulation through a bi-directional mechanism of inducing lipolysis as well as promoting lipid droplet formation. However, whether and how autophagy influences lipid accumulation in kidney fibrosis remain unclear. In the current study, we show that UUO-induced lipid accumulation in tubular cells was significantly reduced when the pharmacological inhibitor 3-MA or CQ was administrated both in vivo and in vitro. Of interest, colocalization of LDs and autophagosomes, as well as colocalization of LDs and lysosomes were undetected in UUO-induced fibrotic kidneys, although lysosome function remained robust, indicating the lipid accumulation is lipophagy-lysosome pathway independent. TGF-β1-induced lipid droplets formation in HK-2 cells were decreased when the Beclin-1 expression was silenced, implying that autophagy-upregulated lipid droplets formation is Beclin-1 dependent. Finally, CQ treatment of UUO-induced fibrotic kidneys reduced the expression of α-SMA and tubular cell apoptosis and rescued the expression of E-cadherin, which was associated with the ameliorated lipid deposition. Therefore, our work documented that autophagy promotes lipid droplet formation in TECs in a Beclin-1-dependent manner, which causes renal lipotoxicity and contributes to the progression of kidney fibrosis.
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Affiliation(s)
- Qi Yan
- 1Department of Nephrology, Renmin hospital of Wuhan University, Wuhan, China.,2Department of Geriatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Yuan Song
- 1Department of Nephrology, Renmin hospital of Wuhan University, Wuhan, China
| | - Lu Zhang
- 1Department of Nephrology, Renmin hospital of Wuhan University, Wuhan, China
| | - Zhaowei Chen
- 1Department of Nephrology, Renmin hospital of Wuhan University, Wuhan, China
| | - Cheng Yang
- 1Department of Nephrology, Renmin hospital of Wuhan University, Wuhan, China
| | - Shan Liu
- 3Department of Nephrology, University Hospital of Hubei University for Nationalities, Enshi, China
| | - Xiaohan Yuan
- 1Department of Nephrology, Renmin hospital of Wuhan University, Wuhan, China
| | - Hongyu Gao
- 2Department of Geriatrics, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China
| | - Guohua Ding
- 1Department of Nephrology, Renmin hospital of Wuhan University, Wuhan, China
| | - Huiming Wang
- 1Department of Nephrology, Renmin hospital of Wuhan University, Wuhan, China
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20
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Chung KW, Lee EK, Lee MK, Oh GT, Yu BP, Chung HY. Impairment of PPAR α and the Fatty Acid Oxidation Pathway Aggravates Renal Fibrosis during Aging. J Am Soc Nephrol 2018; 29:1223-1237. [PMID: 29440279 DOI: 10.1681/asn.2017070802] [Citation(s) in RCA: 161] [Impact Index Per Article: 26.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2017] [Accepted: 01/03/2018] [Indexed: 01/07/2023] Open
Abstract
Defects in the renal fatty acid oxidation (FAO) pathway have been implicated in the development of renal fibrosis. Although, compared with young kidneys, aged kidneys show significantly increased fibrosis with impaired kidney function, the mechanisms underlying the effects of aging on renal fibrosis have not been investigated. In this study, we investigated peroxisome proliferator-activated receptor α (PPARα) and the FAO pathway as regulators of age-associated renal fibrosis. The expression of PPARα and the FAO pathway-associated proteins significantly decreased with the accumulation of lipids in the renal tubular epithelial region during aging in rats. In particular, decreased PPARα protein expression associated with increased expression of PPARα-targeting microRNAs. Among the microRNAs with increased expression during aging, miR-21 efficiently decreased PPARα expression and impaired FAO when ectopically expressed in renal epithelial cells. In cells pretreated with oleic acid to induce lipid stress, miR-21 treatment further enhanced lipid accumulation. Furthermore, treatment with miR-21 significantly exacerbated the TGF-β-induced fibroblast phenotype of epithelial cells. We verified the physiologic importance of our findings in a calorie restriction model. Calorie restriction rescued the impaired FAO pathway during aging and slowed fibrosis development. Finally, compared with kidneys of aged littermate controls, kidneys of aged PPARα-/- mice showed exaggerated lipid accumulation, with decreased activity of the FAO pathway and a severe fibrosis phenotype. Our results suggest that impaired renal PPARα signaling during aging aggravates renal fibrosis development, and targeting PPARα is useful for preventing age-associated CKD.
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Affiliation(s)
- Ki Wung Chung
- Molecular Inflammation Research Center for Aging Intervention and.,Department of Pharmacy, College of Pharmacy, Pusan National University, Busan, Republic of Korea
| | - Eun Kyeong Lee
- Molecular Inflammation Research Center for Aging Intervention and.,Department of Pharmacy, College of Pharmacy, Pusan National University, Busan, Republic of Korea.,Korea Institute of Toxicology, Yuseong-gu, Daejeon, Republic of Korea
| | - Mi Kyung Lee
- Department of Pathology, Ilsin Christian Hospital, Busan, Republic of Korea
| | - Goo Taeg Oh
- Department of Life Sciences, Ewha Womans University, Seoul, Republic of Korea; and
| | - Byung Pal Yu
- Department of Physiology, The University of Texas Health Science Center at San Antonio, San Antonio, Texas
| | - Hae Young Chung
- Molecular Inflammation Research Center for Aging Intervention and .,Department of Pharmacy, College of Pharmacy, Pusan National University, Busan, Republic of Korea
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Grams ME, Tin A, Rebholz CM, Shafi T, Köttgen A, Perrone RD, Sarnak MJ, Inker LA, Levey AS, Coresh J. Metabolomic Alterations Associated with Cause of CKD. Clin J Am Soc Nephrol 2017; 12:1787-1794. [PMID: 28971980 PMCID: PMC5672969 DOI: 10.2215/cjn.02560317] [Citation(s) in RCA: 46] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2017] [Accepted: 07/10/2017] [Indexed: 12/14/2022]
Abstract
BACKGROUND AND OBJECTIVES Causes of CKD differ in prognosis and treatment. Metabolomic indicators of CKD cause may provide clues regarding the different physiologic processes underlying CKD development and progression. DESIGN, SETTING, PARTICIPANTS & MEASUREMENTS Metabolites were quantified from serum samples of participants in the Modification of Diet in Renal Disease (MDRD) Study, a randomized controlled trial of dietary protein restriction and BP control, using untargeted reverse phase ultraperformance liquid chromatography tandem mass spectrometry quantification. Known, nondrug metabolites (n=687) were log-transformed and analyzed to discover associations with CKD cause (polycystic kidney disease, glomerular disease, and other cause). Discovery was performed in Study B, a substudy of MDRD with low GFR (n=166), and replication was performed in Study A, a substudy of MDRD with higher GFR (n=423). RESULTS Overall in MDRD, average participant age was 51 years and 61% were men. In the discovery study (Study B), 29% of participants had polycystic kidney disease, 28% had glomerular disease, and 43% had CKD of another cause; in the replication study (Study A), the percentages were 28%, 24%, and 48%, respectively. In the discovery analysis, adjusted for demographics, randomization group, body mass index, hypertensive medications, measured GFR, log-transformed proteinuria, and estimated protein intake, seven metabolites (16-hydroxypalmitate, kynurenate, homovanillate sulfate, N2,N2-dimethylguanosine, hippurate, homocitrulline, and 1,5-anhydroglucitol) were associated with CKD cause after correction for multiple comparisons (P<0.0008). Five of these metabolite associations (16-hydroxypalmitate, kynurenate, homovanillate sulfate, N2,N2-dimethylguanosine, and hippurate) were replicated in Study A (P<0.007), with all replicated metabolites exhibiting higher levels in polycystic kidney disease and lower levels in glomerular disease compared with CKD of other causes. CONCLUSIONS Metabolomic profiling identified several metabolites strongly associated with cause of CKD.
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Affiliation(s)
- Morgan E. Grams
- Division of Nephrology, Department of Medicine, and
- Welch Center for Prevention, Epidemiology, and Clinical Research, Johns Hopkins University, Baltimore, Maryland
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Adrienne Tin
- Welch Center for Prevention, Epidemiology, and Clinical Research, Johns Hopkins University, Baltimore, Maryland
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Casey M. Rebholz
- Welch Center for Prevention, Epidemiology, and Clinical Research, Johns Hopkins University, Baltimore, Maryland
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Tariq Shafi
- Division of Nephrology, Department of Medicine, and
- Welch Center for Prevention, Epidemiology, and Clinical Research, Johns Hopkins University, Baltimore, Maryland
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
| | - Anna Köttgen
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
- Institute of Genetic Epidemiology, Faculty of Medicine and Medical Center, University of Freiburg, Freiburg, Germany; and
| | - Ronald D. Perrone
- Division of Nephrology, Department of Medicine, Tufts Medical Center, Tufts University School of Medicine, Boston, Massachusetts
| | - Mark J. Sarnak
- Division of Nephrology, Department of Medicine, Tufts Medical Center, Tufts University School of Medicine, Boston, Massachusetts
| | - Lesley A. Inker
- Division of Nephrology, Department of Medicine, Tufts Medical Center, Tufts University School of Medicine, Boston, Massachusetts
| | - Andrew S. Levey
- Division of Nephrology, Department of Medicine, Tufts Medical Center, Tufts University School of Medicine, Boston, Massachusetts
| | - Josef Coresh
- Welch Center for Prevention, Epidemiology, and Clinical Research, Johns Hopkins University, Baltimore, Maryland
- Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland
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22
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Sas KM, Kayampilly P, Byun J, Nair V, Hinder LM, Hur J, Zhang H, Lin C, Qi NR, Michailidis G, Groop PH, Nelson RG, Darshi M, Sharma K, Schelling JR, Sedor JR, Pop-Busui R, Weinberg JM, Soleimanpour SA, Abcouwer SF, Gardner TW, Burant CF, Feldman EL, Kretzler M, Brosius FC, Pennathur S. Tissue-specific metabolic reprogramming drives nutrient flux in diabetic complications. JCI Insight 2016; 1:e86976. [PMID: 27699244 PMCID: PMC5033761 DOI: 10.1172/jci.insight.86976] [Citation(s) in RCA: 173] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 08/16/2016] [Indexed: 12/15/2022] Open
Abstract
Diabetes is associated with altered cellular metabolism, but how altered metabolism contributes to the development of diabetic complications is unknown. We used the BKS db/db diabetic mouse model to investigate changes in carbohydrate and lipid metabolism in kidney cortex, peripheral nerve, and retina. A systems approach using transcriptomics, metabolomics, and metabolic flux analysis identified tissue-specific differences, with increased glucose and fatty acid metabolism in the kidney, a moderate increase in the retina, and a decrease in the nerve. In the kidney, increased metabolism was associated with enhanced protein acetylation and mitochondrial dysfunction. To confirm these findings in human disease, we analyzed diabetic kidney transcriptomic data and urinary metabolites from a cohort of Southwestern American Indians. The urinary findings were replicated in 2 independent patient cohorts, the Finnish Diabetic Nephropathy and the Family Investigation of Nephropathy and Diabetes studies. Increased concentrations of TCA cycle metabolites in urine, but not in plasma, predicted progression of diabetic kidney disease, and there was an enrichment of pathways involved in glycolysis and fatty acid and amino acid metabolism. Our findings highlight tissue-specific changes in metabolism in complication-prone tissues in diabetes and suggest that urinary TCA cycle intermediates are potential prognostic biomarkers of diabetic kidney disease progression.
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Affiliation(s)
| | | | | | - Viji Nair
- Department of Internal Medicine
- Department of Computational Medicine and Bioinformatics
| | - Lucy M. Hinder
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA
| | - Junguk Hur
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, USA
| | | | | | | | - George Michailidis
- Department of Statistics, University of Michigan, Ann Arbor, Michigan, USA
| | - Per-Henrik Groop
- Folkhälsan Institute of Genetics, Folkhälsan Research Center, Biomedicum Helsinki, Helsinki, Finland
- Abdominal Center Nephrology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
- Baker IDI Heart and Diabetes Institute, Melbourne, Australia
| | - Robert G. Nelson
- Diabetes Epidemiology and Clinical Research Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, Arizona, USA
| | - Manjula Darshi
- Institute of Metabolomic Medicine and Center for Renal Translational Medicine, Department of Medicine, University of California San Diego, and Veterans Administration San Diego Healthcare System, La Jolla, California, USA
| | - Kumar Sharma
- Institute of Metabolomic Medicine and Center for Renal Translational Medicine, Department of Medicine, University of California San Diego, and Veterans Administration San Diego Healthcare System, La Jolla, California, USA
| | | | - John R. Sedor
- Department of Medicine
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio, USA
| | | | | | | | | | | | - Charles F. Burant
- Department of Internal Medicine
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, USA
| | - Eva L. Feldman
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA
| | - Matthias Kretzler
- Department of Internal Medicine
- Department of Computational Medicine and Bioinformatics
| | - Frank C. Brosius
- Department of Internal Medicine
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, USA
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23
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Stern JH, Rutkowski JM, Scherer PE. Adiponectin, Leptin, and Fatty Acids in the Maintenance of Metabolic Homeostasis through Adipose Tissue Crosstalk. Cell Metab 2016; 23:770-84. [PMID: 27166942 PMCID: PMC4864949 DOI: 10.1016/j.cmet.2016.04.011] [Citation(s) in RCA: 677] [Impact Index Per Article: 84.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Metabolism research has made tremendous progress over the last several decades in establishing the adipocyte as a central rheostat in the regulation of systemic nutrient and energy homeostasis. Operating at multiple levels of control, the adipocyte communicates with organ systems to adjust gene expression, glucoregulatory hormone exocytosis, enzymatic reactions, and nutrient flux to equilibrate the metabolic demands of a positive or negative energy balance. The identification of these mechanisms has great potential to identify novel targets for the treatment of diabetes and related metabolic disorders. Herein, we review the central role of the adipocyte in the maintenance of metabolic homeostasis, highlighting three critical mediators: adiponectin, leptin, and fatty acids.
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Affiliation(s)
- Jennifer H Stern
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Joseph M Rutkowski
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Philipp E Scherer
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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24
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Abstract
The longstanding focus in chronic kidney disease (CKD) research has been on the glomerulus, which is sensible because this is where glomerular filtration occurs, and a large proportion of progressive CKD is associated with significant glomerular pathology. However, it has been known for decades that tubular atrophy is also a hallmark of CKD and that it is superior to glomerular pathology as a predictor of glomerular filtration rate decline in CKD. Nevertheless, there are vastly fewer studies that investigate the causes of tubular atrophy, and fewer still that identify potential therapeutic targets. The purpose of this review is to discuss plausible mechanisms of tubular atrophy, including tubular epithelial cell apoptosis, cell senescence, peritubular capillary rarefaction and downstream tubule ischemia, oxidative stress, atubular glomeruli, epithelial-to-mesenchymal transition, interstitial inflammation, lipotoxicity and Na(+)/H(+) exchanger-1 inactivation. Once a a better understanding of tubular atrophy (and interstitial fibrosis) pathophysiology has been obtained, it might then be possible to consider tandem glomerular and tubular therapeutic strategies, in a manner similar to cancer chemotherapy regimens, which employ multiple drugs to simultaneously target different mechanistic pathways.
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25
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Li SY, Susztak K. Fat Burning Problem in Cystic Kidneys: an Emerging Common Mechanism of Chronic Kidney Disease. EBioMedicine 2016; 5:22-3. [PMID: 27077105 PMCID: PMC4816831 DOI: 10.1016/j.ebiom.2016.02.035] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
Affiliation(s)
- Szu Yuan Li
- Renal-Electrolyte and Hypertension Division, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, 415 Curie Blvd, Philadelphia, PA 19104, USA; Division of Nephrology, Department of Medicine, Taipei Veterans General Hospital and School of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Katalin Susztak
- Renal-Electrolyte and Hypertension Division, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, 415 Curie Blvd, Philadelphia, PA 19104, USA
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26
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Insulin Therapy of Nondiabetic Septic Patients Is Predicted by para-Tyrosine/Phenylalanine Ratio and by Hydroxyl Radical-Derived Products of Phenylalanine. OXIDATIVE MEDICINE AND CELLULAR LONGEVITY 2015; 2015:839748. [PMID: 26576228 PMCID: PMC4630663 DOI: 10.1155/2015/839748] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/10/2015] [Accepted: 03/03/2015] [Indexed: 12/29/2022]
Abstract
Hydroxyl radical converts Phe to para-, meta-, and ortho-Tyr (p-Tyr, m-Tyr, o-Tyr), while Phe is converted enzymatically to p-Tyr in the kidney and could serve as substrate for gluconeogenesis. Pathological isoforms m- and o-Tyr are supposed to be involved in development of hormone resistances. Role of Phe and the three Tyr isoforms in influencing insulin need was examined in 25 nondiabetic septic patients. Daily insulin dose (DID) and insulin-glucose product (IGP) were calculated. Serum and urinary levels of Phe and Tyr isoforms were determined using a rpHPLC-method. Urinary m-Tyr/p-Tyr ratio was higher in patients with DID and IGP over median compared to those below median (P = 0.005 and P = 0.01, resp.). Urinary m-Tyr and m-Tyr/p-Tyr ratio showed positive correlation with DID (P = 0.009 and P = 0.023, resp.) and with IGP (P = 0.004 and P = 0.008, resp.). Serum Phe was a negative predictor, while serum p-Tyr/Phe ratio was positive predictor of both DID and IGP. Urinary m-Tyr and urinary m-Tyr/p-Tyr, o-Tyr/p-Tyr, and (m-Tyr+o-Tyr)/p-Tyr ratios were positive predictors of both DID and IGP. Phe and Tyr isoforms have a predictive role in carbohydrate metabolism of nondiabetic septic patients. Phe may serve as substrate for renal gluconeogenesis via enzymatically produced p-Tyr, while hydroxyl radical derived Phe products may interfere with insulin action.
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27
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Simon N, Hertig A. Alteration of Fatty Acid Oxidation in Tubular Epithelial Cells: From Acute Kidney Injury to Renal Fibrogenesis. Front Med (Lausanne) 2015; 2:52. [PMID: 26301223 PMCID: PMC4525064 DOI: 10.3389/fmed.2015.00052] [Citation(s) in RCA: 110] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 07/17/2015] [Indexed: 12/11/2022] Open
Abstract
Renal proximal tubular cells are the most energy-demanding cells in the body. The ATP that they use is mostly produced in their mitochondrial and peroxisomal compartments, by the oxidation of fatty acids. When those cells are placed under a biological stress, such as a transient hypoxia, fatty acid oxidation (FAO) is shut down for a period of time that outlasts injury, and carbohydrate oxidation does not take over. Facing those metabolic constraints, surviving tubular epithelial cells exhibit a phenotypic switch that includes cytoskeletal rearrangement and production of extracellular matrix proteins, most probably contributing to acute kidney injury-induced renal fibrogenesis, thence to the development of chronic kidney disease. Here, we review experimental evidence that dysregulation of FAO profoundly affects the fate of tubular epithelial cells, by promoting epithelial-to-mesenchymal transition, inflammation, and eventually interstitial fibrosis. Restoring physiological production of energy is undoubtedly a possible therapeutic approach to unlock the mesenchymal reprograming of tubular epithelial cells in the kidney. In this respect, the benefit of the use of fibrates is uncertain, but new drugs that could specifically target this metabolic pathway, and, hopefully, attenuate renal fibrosis merit future research.
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Affiliation(s)
- Noémie Simon
- IMSERM UMR_S1155, Rare and Common Kidney Diseases, Remodeling and Tissue Repair, Hôpital Tenon , Paris , France
| | - Alexandre Hertig
- IMSERM UMR_S1155, Rare and Common Kidney Diseases, Remodeling and Tissue Repair, Hôpital Tenon , Paris , France ; UMR S 1155, UPMC Sorbonne Université Paris 06 , Paris , France
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28
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Han SH, Malaga-Dieguez L, Chinga F, Kang HM, Tao J, Reidy K, Susztak K. Deletion of Lkb1 in Renal Tubular Epithelial Cells Leads to CKD by Altering Metabolism. J Am Soc Nephrol 2015; 27:439-53. [PMID: 26054542 DOI: 10.1681/asn.2014121181] [Citation(s) in RCA: 88] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2014] [Accepted: 04/12/2015] [Indexed: 12/30/2022] Open
Abstract
Renal tubule epithelial cells are high-energy demanding polarized epithelial cells. Liver kinase B1 (LKB1) is a key regulator of polarity, proliferation, and cell metabolism in epithelial cells, but the function of LKB1 in the kidney is unclear. Our unbiased gene expression studies of human control and CKD kidney samples identified lower expression of LKB1 and regulatory proteins in CKD. Mice with distal tubule epithelial-specific Lkb1 deletion (Ksp-Cre/Lkb1(flox/flox)) exhibited progressive kidney disease characterized by flattened dedifferentiated tubule epithelial cells, interstitial matrix accumulation, and dilated cystic-appearing tubules. Expression of epithelial polarity markers β-catenin and E-cadherin was not altered even at later stages. However, expression levels of key regulators of metabolism, AMP-activated protein kinase (Ampk), peroxisome proliferative activated receptor gamma coactivator 1-α (Ppargc1a), and Ppara, were significantly lower than those in controls and correlated with fibrosis development. Loss of Lkb1 in cultured epithelial cells resulted in energy depletion, apoptosis, less fatty acid oxidation and glycolysis, and a profibrotic phenotype. Treatment of Lkb1-deficient cells with an AMP-activated protein kinase (AMPK) agonist (A769662) or a peroxisome proliferative activated receptor alpha agonist (fenofibrate) restored the fatty oxidation defect and reduced apoptosis. In conclusion, we show that loss of LKB1 in renal tubular epithelial cells has an important role in kidney disease development by influencing intracellular metabolism.
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Affiliation(s)
- Seung Hyeok Han
- Renal Electrolyte and Hypertension Division, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Department of Internal Medicine, Yonsei University College of Medicine, Seoul, Korea
| | - Laura Malaga-Dieguez
- Renal Electrolyte and Hypertension Division, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Frank Chinga
- Renal Electrolyte and Hypertension Division, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Hyun Mi Kang
- Renal Electrolyte and Hypertension Division, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania
| | - Jianling Tao
- Renal Electrolyte and Hypertension Division, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Division of Nephrology, Peking Union Medical College Hospital, Peking Union Medical College and Chinese Academy of Medical Sciences, Beijing, China
| | - Kimberly Reidy
- Renal Electrolyte and Hypertension Division, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania; Children's Hospital at Montefiore, Albert Einstein College of Medicine, Bronx, New York; and
| | - Katalin Susztak
- Renal Electrolyte and Hypertension Division, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania;
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29
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Woolcott OO, Ader M, Bergman RN. Glucose homeostasis during short-term and prolonged exposure to high altitudes. Endocr Rev 2015; 36:149-73. [PMID: 25675133 PMCID: PMC4399271 DOI: 10.1210/er.2014-1063] [Citation(s) in RCA: 76] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Most of the literature related to high altitude medicine is devoted to the short-term effects of high-altitude exposure on human physiology. However, long-term effects of living at high altitudes may be more important in relation to human disease because more than 400 million people worldwide reside above 1500 m. Interestingly, individuals living at higher altitudes have a lower fasting glycemia and better glucose tolerance compared with those who live near sea level. There is also emerging evidence of the lower prevalence of both obesity and diabetes at higher altitudes. The mechanisms underlying improved glucose control at higher altitudes remain unclear. In this review, we present the most current evidence about glucose homeostasis in residents living above 1500 m and discuss possible mechanisms that could explain the lower fasting glycemia and lower prevalence of obesity and diabetes in this population. Understanding the mechanisms that regulate and maintain the lower fasting glycemia in individuals who live at higher altitudes could lead to new therapeutics for impaired glucose homeostasis.
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Affiliation(s)
- Orison O Woolcott
- Diabetes and Obesity Research Institute, Cedars-Sinai Medical Center, Los Angeles, California 90048
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30
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Kang HM, Ahn SH, Choi P, Ko YA, Han SH, Chinga F, Park ASD, Tao J, Sharma K, Pullman J, Bottinger EP, Goldberg IJ, Susztak K. Defective fatty acid oxidation in renal tubular epithelial cells has a key role in kidney fibrosis development. Nat Med 2014; 21:37-46. [PMID: 25419705 DOI: 10.1038/nm.3762] [Citation(s) in RCA: 967] [Impact Index Per Article: 96.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Accepted: 10/17/2014] [Indexed: 12/20/2022]
Abstract
Renal fibrosis is the histological manifestation of a progressive, usually irreversible process causing chronic and end-stage kidney disease. We performed genome-wide transcriptome studies of a large cohort (n = 95) of normal and fibrotic human kidney tubule samples followed by systems and network analyses and identified inflammation and metabolism as the top dysregulated pathways in the diseased kidneys. In particular, we found that humans and mouse models with tubulointerstitial fibrosis had lower expression of key enzymes and regulators of fatty acid oxidation (FAO) and higher intracellular lipid deposition compared to controls. In vitro experiments indicated that inhibition of FAO in tubule epithelial cells caused ATP depletion, cell death, dedifferentiation and intracellular lipid deposition, phenotypes observed in fibrosis. In contrast, restoring fatty acid metabolism by genetic or pharmacological methods protected mice from tubulointerstitial fibrosis. Our results raise the possibility that correcting the metabolic defect in FAO may be useful for preventing and treating chronic kidney disease.
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Affiliation(s)
- Hyun Mi Kang
- Renal Electrolyte and Hypertension Division, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Seon Ho Ahn
- Renal Electrolyte and Hypertension Division, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Peter Choi
- Renal Electrolyte and Hypertension Division, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Yi-An Ko
- Renal Electrolyte and Hypertension Division, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Seung Hyeok Han
- Renal Electrolyte and Hypertension Division, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Frank Chinga
- Renal Electrolyte and Hypertension Division, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Ae Seo Deok Park
- Renal Electrolyte and Hypertension Division, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Jianling Tao
- Renal Electrolyte and Hypertension Division, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
| | - Kumar Sharma
- Division of Nephrology, Department of Medicine, University of California, San Diego, Veterans Administration San Diego HealthCare System, La Jolla, California, USA
| | - James Pullman
- Department of Pathology, Albert Einstein College of Medicine, Montefiore Medical Center, Bronx, New York, USA
| | - Erwin P Bottinger
- Department of Medicine, Mount Sinai School of Medicine, New York, New York, USA
| | - Ira J Goldberg
- Department of Medicine, New York University Langone Medical Center, New York, New York, USA
| | - Katalin Susztak
- Renal Electrolyte and Hypertension Division, Perelman School of Medicine, University of Pennsylvania, Philadelphia, Pennsylvania, USA
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31
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Nakaya Y, Shimohata T, Haraguchi S, Nakao T, Minaguchi J, Sumitani H, Harada N, Sakaue H. Severe catabolic state after an overnight fast in patients with chronic renal failure. Nutrition 2011; 27:329-32. [DOI: 10.1016/j.nut.2010.04.008] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2009] [Revised: 04/27/2010] [Accepted: 04/27/2010] [Indexed: 11/30/2022]
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32
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Bobulescu IA, Dubree M, Zhang J, McLeroy P, Moe OW. Effect of renal lipid accumulation on proximal tubule Na+/H+ exchange and ammonium secretion. Am J Physiol Renal Physiol 2008; 294:F1315-22. [PMID: 18417539 DOI: 10.1152/ajprenal.00550.2007] [Citation(s) in RCA: 79] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Patients with metabolic syndrome have increased risk of uric acid nephrolithiasis due to lower urinary pH and impaired ammonium excretion. The pathophysiology underlying these urinary changes is unknown. We used two animal models and a cell culture model to study whether the alteration in renal acidification is associated with renal fat infiltration (steatosis). Compared with pair-fed lean control rats, Zucker diabetic fatty rats have higher renal triglyceride content, decreased urinary ammonium and pH, and lower levels of brush border membrane Na(+)/H(+) exchanger-3 (NHE3), a major mediator of ammonium excretion. High-fat feeding in Sprague-Dawley rats results in transient lowering of urinary ammonium and pH, with all parameters returning to normal when the animals resumed eating normal chow. This is consistent with an absence of diet-induced renal steatosis in these animals. To examine the direct effect of fat accumulation, we incubated opossum kidney (OKP) cells with a mixture of long-chain fatty acids and found accumulation of intracellular lipids with concomitant dose-dependent decrease in NHE3 activity, surface biotin-accessible NHE3 protein, and ammonium secretion. A lower dose of fatty acids that leads to intracellular lipid accumulation but does not change baseline NHE3 is sufficient to abolish the stimulation of NHE3 by insulin and to partially block the stimulation of NHE3 by glucocorticoid hormones; acid regulation of NHE3 in lipid-loaded OKP cells is not affected. These findings suggest that renal steatosis decreases ammonium secretion in the proximal tubule, in part by reducing NHE3 activity and by impairing the regulation of NHE3 by specific agonists.
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Affiliation(s)
- I Alexandru Bobulescu
- Dept. of Internal Medicine, Univ. of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390-8856, USA
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33
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Karpe F, Fielding BA, Coppack SW, Lawrence VJ, Macdonald IA, Frayn KN. Oscillations of fatty acid and glycerol release from human subcutaneous adipose tissue in vivo. Diabetes 2005; 54:1297-303. [PMID: 15855313 DOI: 10.2337/diabetes.54.5.1297] [Citation(s) in RCA: 17] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
We sought evidence for pulsatility of lipolysis in human subcutaneous adipose tissue in vivo. Arterialized and adipose tissue venous blood samples were drawn at 2-min intervals from nine healthy subjects. This procedure was repeated during hyperinsulinemic-euglycemic clamp to remove insulin pulsatility. We found evidence for pulsatile release of both nonesterified fatty acids (NEFAs) (seven of nine subjects) and glycerol (five of six subjects) with a period of approximately 12-14 min. This pulsatility was maintained even during the hyperinsulinemic clamp. Checks were made for spurious pulse detection, including the creation of "mock" venoarterialized differences by subtracting one subject's arterialized concentrations from another's venous; the peaks detected were less consistent in character than with real data (peak width, P = 0.006; peak interval, P < 0.004). Significant cross-correlations between NEFA and glycerol release also provided evidence of a real effect. Arterialized norepinephrine concentrations were also pulsatile, but the period did not match that of NEFA and glycerol release. Insulin concentrations were pulsatile with a typical period of 12 min, but this was not significantly cross-correlated with lipolysis. We conclude that release from adipose tissue of the products of lipolysis is pulsatile in humans.
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Affiliation(s)
- Fredrik Karpe
- Oxford Centre for Diabetes, Endocrinology and Metabolism, Churchill Hospital, Oxford OX3 7LJ, UK
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34
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Meyer C, Woerle HJ, Dostou JM, Welle SL, Gerich JE. Abnormal renal, hepatic, and muscle glucose metabolism following glucose ingestion in type 2 diabetes. Am J Physiol Endocrinol Metab 2004; 287:E1049-56. [PMID: 15304374 DOI: 10.1152/ajpendo.00041.2004] [Citation(s) in RCA: 87] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Recent studies indicate an important role of the kidney in postprandial glucose homeostasis in normal humans. To determine its role in the abnormal postprandial glucose metabolism in type 2 diabetes mellitus (T2DM), we used a combination of the dual-isotope technique and net balance measurements across kidney and skeletal muscle in 10 subjects with T2DM and 10 age-, weight-, and sex-matched nondiabetic volunteers after ingestion of 75 g of glucose. Over the 4.5-h postprandial period, diabetic subjects had increased mean blood glucose levels (14.1 +/- 1.1 vs. 6.2 +/- 0.2 mM, P < 0.001) and increased systemic glucose appearance (100.0 +/- 6.3 vs. 70.0 +/- 3.3 g, P < 0.001). The latter was mainly due to approximately 23 g greater endogenous glucose release (39.8 +/- 5.9 vs. 17.0 +/- 1.8 g, P < 0.002), since systemic appearance of the ingested glucose was increased by only approximately 7 g (60.2 +/- 1.4 vs. 53.0 +/- 2.2 g, P < 0.02). Approximately 40% of the diabetic subjects' increased endogenous glucose release was due to increased renal glucose release (19.6 +/- 3.1 vs. 10.6 +/- 2.4 g, P < 0.05). Postprandial systemic tissue glucose uptake was also increased in the diabetic subjects (82.3 +/- 4.7 vs. 69.8 +/- 3.5 g, P < 0.05), and its distribution was altered; renal glucose uptake was increased (21.0 +/- 3.5 vs. 9.8 +/- 2.3 g, P < 0.03), whereas muscle glucose uptake was normal (18.5 +/- 1.8 vs. 25.9 +/- 3.3 g, P = 0.16). We conclude that, in T2DM, 1) both liver and kidney contribute to postprandial overproduction of glucose, and 2) postprandial renal glucose uptake is increased, resulting in a shift in the relative importance of muscle and kidney for glucose disposal. The latter may provide an explanation for the renal glycogen accumulation characteristic of diabetes mellitus as well as a mechanism by which hyperglycemia may lead to diabetic nephropathy.
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Affiliation(s)
- Christian Meyer
- Department of Medicine, University of Rochester School of Medicine, Rochester, NY 14642, USA.
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35
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Woerle HJ, Meyer C, Popa EM, Cryer PE, Gerich JE. Renal compensation for impaired hepatic glucose release during hypoglycemia in type 2 diabetes: further evidence for hepatorenal reciprocity. Diabetes 2003; 52:1386-92. [PMID: 12765948 DOI: 10.2337/diabetes.52.6.1386] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
During liver transplantation and after both meal ingestion and prolonged fasting, renal glucose release (RGR) increases while hepatic glucose release (HGR) decreases. These and other observations have led to the concept of hepatorenal reciprocity. According to this concept, reciprocal changes in hepatic and renal glucose release may occur to minimize deviations from normal glucose homeostasis. We further assessed this concept by testing the hypothesis that during counterregulation of hypoglycemia in patients with type 2 diabetes, who would be expected to have reduced HGR, RGR would be increased. Accordingly, we performed hypoglycemic hyperinsulinemic clamp experiments (approximately 3.1 mmol/l) in 12 type 2 diabetic and in 10 age-weight-matched nondiabetic volunteers and measured total endogenous glucose release (TEGR) and RGR using a combined isotopic net balance approach. HGR was calculated as the difference between TEGR and RGR since only these organs are capable of releasing glucose. We found that during comparable hypoglycemia and hyperinsulinemia, TEGR was reduced in type 2 diabetes (6.6 +/- 0.6 vs. 10.2 +/- 1.1 micromol. kg(-1). min(-1) in nondiabetic volunteers, P = 0.01) due to reduced HGR (3.9 +/- 0.5 vs. 8.6 +/- 1.0 micromol. kg(-1). min(-1) in nondiabetic volunteers, P = 0.0015). In contrast, RGR was increased approximately twofold in type 2 diabetes (3.3 +/- 0.5 vs. 1.6 +/- 0.3 micromol. kg(-1). min(-1) in nondiabetic volunteers, P = 0.015). Plasma epinephrine, lactate, and free fatty acid concentrations, which would promote RGR, were also greater in type 2 diabetes (all P < 0.01). Our results provide further support for hepatorenal reciprocity and may explain at least in part the relatively low occurrence of severe hypoglycemia in type 2 diabetes compared with type 1 diabetes where both HGR and RGR counterregulatory responses are reduced.
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Affiliation(s)
- Hans J Woerle
- Department of Medicine, University of Rochester School of Medicine, 601 Elmwood Avenue, Rochester, NY 14642, USA
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Abstract
Data obtained from net organ balance studies of glucose production lead to the classic view according to which glucose homeostasis is mainly ensured by the liver, and renal glucose production only plays a significant role during acidosis and prolonged starvation. Renal glucose release and uptake, as well as the participation of gluconeogenic substrates in renal gluconeogenesis, were recently re-evaluated using systemic and renal arteriovenous balance of substrates in combination with deuterated glucose dilution. Data obtained using these methods lead one to reconsider the magnitude of renal glucose production as well as its role in various physiological and pathological circumstances. These findings now conduce one to consider that renal gluconeogenesis substantially participates in postabsorptive glucose production, and that its role in glucose homeostasis is of first importance.
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Affiliation(s)
- Noël Cano
- Service d'Hépatogastroenterologie et Nutrition, Clinique Résidence du Parc, Rue Gaston Berger, 13010 Marseille, France.
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Abstract
Overproduction of glucose is the major factor responsible for fasting hyperglycemia in type 2 diabetes. Formerly, this had been considered to be solely due to excessive hepatic glucose production because the human kidney was not regarded as an important source of glucose except during acidosis and after prolonged fasting. However, data accumulated over the last 60 years in animal and in vitro studies have provided considerable evidence that the kidney plays an important role in glucose homeostasis in conditions other than acidosis and prolonged fasting. This article summarizes early work in animals and humans, discusses methodologic issues in assessing renal glucose release in vivo, and provides evidence from recent human studies that the kidney substantially contributes to glucose overproduction in type 2 diabetes.
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Affiliation(s)
- Christian Meyer
- Department of Medicine, University of Rochester School of Medicine, 601 Elmwood Avenue, Box MED/CRC, Rochester, NY 14642, USA
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38
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Abstract
Mammals metabolize citrate to acetyl-CoA and oxaloacetate via the enzyme, ATP:citrate lyase. Bacteria lack this enzyme, but have the ability to cleave citrate in the form of citryl-CoA in an analogous manner using a structurally distinct enzyme. We have identified a novel mammalian gene that shows significant amino acid sequence homology to the bacterial CitE gene product that is responsible for cleavage of citryl-CoA. We propose that this gene encodes an enzyme that catalyzes cleavage of substrates related to CoA esters of citrate or an analogous intermediary metabolite. The product of this novel gene may represent a component of an unknown metabolic pathway in mammals.
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Meyer C, Dostou JM, Welle SL, Gerich JE. Role of human liver, kidney, and skeletal muscle in postprandial glucose homeostasis. Am J Physiol Endocrinol Metab 2002; 282:E419-27. [PMID: 11788375 DOI: 10.1152/ajpendo.00032.2001] [Citation(s) in RCA: 182] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
Recent studies indicate a role for the kidney in postabsorptive glucose homeostasis. The present studies were undertaken to evaluate the role of the kidney in postprandial glucose homeostasis and to compare its contribution to that of liver and skeletal muscle. Accordingly, we used the double isotope technique along with forearm and renal balance measurements to assess systemic, renal, and hepatic glucose release as well as glucose uptake by kidney, skeletal muscle, and splanchnic tissues in 10 normal volunteers after ingestion of 75 g of glucose. We found that, during the 4.5-h postprandial period, 22 +/- 2 g (30 +/- 3% of the ingested glucose) were initially extracted by splanchnic tissues. Of the remaining 53 +/- 2 g that entered the systemic circulation, 19 +/- 3 g were calculated to have been taken up by skeletal muscle and 7.5 +/- 1.7 g by the kidney (26 +/- 3 and 10 +/- 2%, respectively, of the ingested glucose). Endogenous glucose release during the postprandial period (16 +/- 2 g), calculated as the difference between overall systemic glucose appearance and the appearance of ingested glucose in the systemic circulation, was suppressed 61 +/- 3%. Surprisingly, renal glucose release increased twofold (10.6 +/- 2.5 g) and accounted for ~60% of postprandial endogenous glucose release. Hepatic glucose release (6.7 +/- 2.2 g), the difference between endogenous and renal glucose release, was suppressed 82 +/- 6%. These results demonstrate a hitherto unappreciated contribution of the kidney to postprandial glucose homeostasis and indicate that postprandial suppression of hepatic glucose release is nearly twofold greater than had been calculated in previous studies (42 +/- 4%), which had assumed that there was no renal glucose release. We postulate that increases in postprandial renal glucose release may play a role in facilitating efficient liver glycogen repletion by permitting substantial suppression of hepatic glucose release.
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Affiliation(s)
- Christian Meyer
- Department of Medicine, University of Rochester School of Medicine, Rochester, New York 14642, USA
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Meyer C, Stumvoll M, Dostou J, Welle S, Haymond M, Gerich J. Renal substrate exchange and gluconeogenesis in normal postabsorptive humans. Am J Physiol Endocrinol Metab 2002; 282:E428-34. [PMID: 11788376 DOI: 10.1152/ajpendo.00116.2001] [Citation(s) in RCA: 86] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Release of glucose by the kidney in postabsorptive normal humans is generally regarded as being wholly due to gluconeogenesis. Although lactate is the most important systemic gluconeogenic precursor and there is appreciable net renal lactate uptake, renal lactate gluconeogenesis has not yet been investigated. The present studies were therefore undertaken to quantitate the contribution of lactate to renal gluconeogenesis and the role of the kidney in lactate metabolism. We determined systemic and renal lactate conversion to glucose as well as renal lactate net balance, fractional extraction, uptake, and release in 24 postabsorptive humans by use of a combination of isotopic and renal balance techniques. For comparative purposes, accumulated similar data for glutamine, alanine, and glycerol are also reported. Systemic lactate gluconeogenesis (1.97 +/- 0.12 micromol x kg(-1) x min(-1)) was about threefold greater than that from glycerol, glutamine, and alanine. The sum of gluconeogenesis from these precursors, uncorrected for tricarboxylic acid (TCA) cycle carbon exchange, explained 34% of systemic glucose release. Renal lactate uptake (3.33 +/- 0.28 micromol x kg(-1) x min(-1)) accounted for nearly 30% of its systemic turnover. Renal gluconeogenesis from lactate (0.78 +/- 0.10 micromol x kg(-1) x min(-1)) was 3.5, 2.5, and 9.6-fold greater than that from glycerol, glutamine, and alanine. The sum of renal gluconeogenesis from these precursors equaled approximately 40% of the sum of their systemic gluconeogenesis. When the isotopically determined rates of systemic and renal gluconeogenesis were corrected for TCA cycle carbon exchange, gluconeogenesis from these precursors accounted for 43% of systemic glucose release and 89% of renal glucose release. We conclude that 1) in postabsorptive normal humans, lactate is the dominant precursor for both renal and systemic gluconeogenesis; 2) the kidney is an important organ for lactate disposal; 3) under these conditions, renal glucose release is predominantly, if not exclusively, due to gluconeogenesis; and 4) liver and kidney are similarly important for systemic gluconeogenesis.
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Affiliation(s)
- Christian Meyer
- Department of Medicine and Physiology, University of Rochester School of Medicine, Rochester, New York 14642, USA
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Nakae J, Kitamura T, Silver DL, Accili D. The forkhead transcription factor Foxo1 (Fkhr) confers insulin sensitivity onto glucose-6-phosphatase expression. J Clin Invest 2001; 108:1359-67. [PMID: 11696581 PMCID: PMC209440 DOI: 10.1172/jci12876] [Citation(s) in RCA: 253] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/26/2023] Open
Abstract
Type 2 diabetes is characterized by the inability of insulin to suppress glucose production in the liver and kidney. Insulin inhibits glucose production by indirect and direct mechanisms. The latter result in transcriptional suppression of key gluconeogenetic and glycogenolytic enzymes, phosphoenolpyruvate carboxykinase (Pepck) and glucose-6-phosphatase (G6p). The transcription factors required for this effect are incompletely characterized. We report that in glucogenetic kidney epithelial cells, Pepck and G6p expression are induced by dexamethasone (dex) and cAMP, but fail to be inhibited by insulin. The inability to respond to insulin is associated with reduced expression of the forkhead transcription factor Foxo1, a substrate of the Akt kinase that is inhibited by insulin through phosphorylation. Transduction of kidney cells with recombinant adenovirus encoding Foxo1 results in insulin inhibition of dex/cAMP-induced G6p expression. Moreover, expression of dominant negative Foxo1 mutant results in partial inhibition of dex/cAMP-induced G6p and Pepck expression in primary cultures of mouse hepatocyes and kidney LLC-PK1-FBPase(+) cells. These findings are consistent with the possibility that Foxo1 is involved in insulin regulation of glucose production by mediating the ability of insulin to decrease the glucocorticoid/cAMP response of G6p.
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Affiliation(s)
- J Nakae
- Naomi Berrie Diabetes Center, College of Physicians and Surgeons, Columbia University, New York, New York 10032, USA
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Båvenholm PN, Pigon J, Ostenson CG, Efendic S. Insulin sensitivity of suppression of endogenous glucose production is the single most important determinant of glucose tolerance. Diabetes 2001; 50:1449-54. [PMID: 11375347 DOI: 10.2337/diabetes.50.6.1449] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Hyperglycemia results from an imbalance between endocrine pancreatic function and hepatic and extrahepatic insulin sensitivity. We studied 57 well-matched Swedish men with normal glucose tolerance (NGT), impaired glucose tolerance (IGT), or mild diabetes. Oral glucose tolerance and insulin release were assessed during an oral glucose tolerance test (OGTT). Insulin sensitivity and glucose turnover were determined during a two-step euglycemic insulin clamp (infusion 0.25 and 1.0 mU. kg(-1). min(-1)). High-performance liquid chromatography-purified [6-(3)H]glucose was used as a tracer. During low-insulin infusion, the rate of endogenous glucose production (EGP) decreased more in subjects with NGT than in subjects with IGT or diabetes (delta rate of appearance [R(a)] 1.25 +/- 0.10 vs. 0.75 +/- 0.14 vs. 0.58 +/- 0.09 mg. kg(-1). min(-1), P < 0.001). The corresponding rates of glucose infusion during the high-dose insulin infusion (M values) were 8.3 +/- 0.6 vs. 5.4 +/- 0.9 vs. 4.7 +/- 0.4 mg. kg(-1). min(-1) (P < 0.001). A total of 56% of the variation in glucose area under the curve (AUC) during OGTT (glucose AUC) was mainly explained by delta R(a) (increase in multiple R(2) 0.42) but also by delta R(d) (rate of disappearance) (increase in multiple R(2) 0.05), and the early insulin response during OGTT contributed significantly (increase in multiple R(2) 0.07). When M value was included in the model, reflecting extrahepatic insulin sensitivity, it contributed to 20% of the variation in glucose AUC, and together with the incremental insulin response (increase in multiple R(2) 0.21), it explained 45% of the variation. In conclusion, insulin sensitivity of suppression of EGP plays the most important role in the determination of blood glucose response during OGTT.
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Affiliation(s)
- P N Båvenholm
- Division of Medicine, Department of Emergency and Cardiovascular Medicine, Karolinska Hospital and Institute, S-171 76 Stockholm, Sweden.
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Meyer C, Stumvoll M, Nadkarni V, Dostou J, Mitrakou A, Gerich J. Abnormal renal and hepatic glucose metabolism in type 2 diabetes mellitus. J Clin Invest 1998; 102:619-24. [PMID: 9691098 PMCID: PMC508922 DOI: 10.1172/jci2415] [Citation(s) in RCA: 214] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Release of glucose by liver and kidney are both increased in diabetic animals. Although the overall release of glucose into the circulation is increased in humans with diabetes, excessive release of glucose by either their liver or kidney has not as yet been demonstrated. The present experiments were therefore undertaken to assess the relative contributions of hepatic and renal glucose release to the excessive glucose release found in type 2 diabetes. Using a combination of isotopic and balance techniques to determine total systemic glucose release and renal glucose release in postabsorptive type 2 diabetic subjects and age-weight-matched nondiabetic volunteers, their hepatic glucose release was then calculated as the difference between total systemic glucose release and renal glucose release. Renal glucose release was increased nearly 300% in diabetic subjects (321+/-36 vs. 125+/-15 micromol/min, P < 0.001). Hepatic glucose release was increased approximately 30% (P = 0.03), but increments in hepatic and renal glucose release were comparable (2.60+/-0.70 vs. 2.21+/-0.32, micromol.kg-1.min-1, respectively, P = 0.26). Renal glucose uptake was markedly increased in diabetic subjects (353+/-48 vs. 103+/-10 micromol/min, P < 0.001), resulting in net renal glucose uptake in the diabetic subjects (92+/-50 micromol/ min) versus a net output in the nondiabetic subjects (21+/-14 micromol/min, P = 0.043). Renal glucose uptake was inversely correlated with renal FFA uptake (r = -0.51, P < 0.01), which was reduced by approximately 60% in diabetic subjects (10. 9+/-2.7 vs. 27.0+/-3.3 micromol/min, P < 0.002). We conclude that in type 2 diabetes, both liver and kidney contribute to glucose overproduction and that renal glucose uptake is markedly increased. The latter may suppress renal FFA uptake via a glucose-fatty acid cycle and explain the accumulation of glycogen commonly found in the diabetic kidney.
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Affiliation(s)
- C Meyer
- Departments of Medicine and Physiology and Pharmacology, University of Rochester School of Medicine, Rochester, New York 14642, USA
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