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Liu DZ, Luo XZ, Lu CH, Feng YY, Chen DX, Zeng ZY, Huang F. Y4 RNA fragments from cardiosphere-derived cells ameliorate diabetic myocardial ischemia‒reperfusion injury by inhibiting protein kinase C β-mediated macrophage polarization. Cardiovasc Diabetol 2024; 23:202. [PMID: 38867293 PMCID: PMC11170846 DOI: 10.1186/s12933-024-02247-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/24/2024] [Accepted: 04/22/2024] [Indexed: 06/14/2024] Open
Abstract
The specific pathophysiological pathways through which diabetes exacerbates myocardial ischemia/reperfusion (I/R) injury remain unclear; however, dysregulation of immune and inflammatory cells, potentially driven by abnormalities in their number and function due to diabetes, may play a significant role. In the present investigation, we simulated myocardial I/R injury by inducing ischemia through ligation of the left anterior descending coronary artery in mice for 40 min, followed by reperfusion for 24 h. Previous studies have indicated that protein kinase Cβ (PKCβ) is upregulated under hyperglycemic conditions and is implicated in the development of various diabetic complications. The Y4 RNA fragment is identified as the predominant small RNA component present in the extracellular vesicles of cardio sphere-derived cells (CDCs), exhibiting notable anti-inflammatory properties in the contexts of myocardial infarction and cardiac hypertrophy. Our investigation revealed that the administration of Y4 RNA into the ventricular cavity of db/db mice following myocardial I/R injury markedly enhanced cardiac function. Furthermore, Y4 RNA was observed to facilitate M2 macrophage polarization and interleukin-10 secretion through the suppression of PKCβ activation. The mechanism by which Y4 RNA affects PKCβ by regulating macrophage activation within the inflammatory environment involves the inhibition of ERK1/2 phosphorylation In our study, the role of PKCβ in regulating macrophage polarization during myocardial I/R injury was investigated through the use of PKCβ knockout mice. Our findings indicate that PKCβ plays a crucial role in modulating the inflammatory response associated with macrophage activation in db/db mice experiencing myocardial I/R, with a notable exacerbation of this response observed upon significant upregulation of PKCβ expression. In vitro studies further elucidated the protective mechanism by which Y4 RNA modulates the PKCβ/ERK1/2 signaling pathway to induce M2 macrophage activation. Overall, our findings suggest that Y4 RNA plays an anti-inflammatory role in diabetic I/R injury, suggesting a novel therapeutic approach for managing myocardial I/R injury in diabetic individuals.
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Affiliation(s)
- De-Zhao Liu
- Department of Cardiology & Guangxi Key Laboratory Base of Precision Medicine in Cardio-Cerebrovascular Diseases Control and Prevention & Guangxi Clinical Research Center for Cardio-Cerebrovascular Diseases, The First Affiliated Hospital of Guangxi Medical University, No.6 Shuangyong Road, Nanning, 530021, Guangxi, China
| | - Xiao-Zhi Luo
- Department of Cardiology & Guangxi Key Laboratory Base of Precision Medicine in Cardio-Cerebrovascular Diseases Control and Prevention & Guangxi Clinical Research Center for Cardio-Cerebrovascular Diseases, The First Affiliated Hospital of Guangxi Medical University, No.6 Shuangyong Road, Nanning, 530021, Guangxi, China
| | - Chuang-Hong Lu
- Department of Cardiology & Guangxi Key Laboratory Base of Precision Medicine in Cardio-Cerebrovascular Diseases Control and Prevention & Guangxi Clinical Research Center for Cardio-Cerebrovascular Diseases, The First Affiliated Hospital of Guangxi Medical University, No.6 Shuangyong Road, Nanning, 530021, Guangxi, China
| | - Yang-Yi Feng
- Department of Cardiology & Guangxi Key Laboratory Base of Precision Medicine in Cardio-Cerebrovascular Diseases Control and Prevention & Guangxi Clinical Research Center for Cardio-Cerebrovascular Diseases, The First Affiliated Hospital of Guangxi Medical University, No.6 Shuangyong Road, Nanning, 530021, Guangxi, China
| | - De-Xin Chen
- Department of Cardiology & Guangxi Key Laboratory Base of Precision Medicine in Cardio-Cerebrovascular Diseases Control and Prevention & Guangxi Clinical Research Center for Cardio-Cerebrovascular Diseases, The First Affiliated Hospital of Guangxi Medical University, No.6 Shuangyong Road, Nanning, 530021, Guangxi, China
| | - Zhi-Yu Zeng
- Department of Cardiology & Guangxi Key Laboratory Base of Precision Medicine in Cardio-Cerebrovascular Diseases Control and Prevention & Guangxi Clinical Research Center for Cardio-Cerebrovascular Diseases, The First Affiliated Hospital of Guangxi Medical University, No.6 Shuangyong Road, Nanning, 530021, Guangxi, China.
| | - Feng Huang
- Department of Cardiology & Guangxi Key Laboratory Base of Precision Medicine in Cardio-Cerebrovascular Diseases Control and Prevention & Guangxi Clinical Research Center for Cardio-Cerebrovascular Diseases, The First Affiliated Hospital of Guangxi Medical University, No.6 Shuangyong Road, Nanning, 530021, Guangxi, China.
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2
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Parwani K, Mandal P. Advanced glycation end products and insulin resistance in diabetic nephropathy. VITAMINS AND HORMONES 2024; 125:117-148. [PMID: 38997162 DOI: 10.1016/bs.vh.2024.02.007] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/14/2024]
Abstract
Insulin resistance is a central hallmark that connects the metabolic syndrome and diabetes to the resultant formation of advanced glycation end products (AGEs), which further results in the complications of diabetes, including diabetic nephropathy. Several factors play an important role as an inducer to diabetic nephropathy, and AGEs elicit their harmful effects via interacting with the receptor for AGEs Receptor for AGEs, by induction of pro-inflammatory cytokines, oxidative stress, endoplasmic reticulum stress and fibrosis in the kidney tissues leading to the loss of renal function. Insulin resistance results in the activation of other alternate pathways governed by insulin, which results in the hypertrophy of the renal cells and tissue remodeling. Apart from the glucose uptake and disposal, insulin dependent PI3K and Akt also upregulate the expression of endothelial nitric oxide synthase, that results in increasing the bioavailability of nitric oxide in the vascular endothelium, which further results in tissue fibrosis. Considering the global prevalence of diabetic nephropathy, and the impact of protein glycation, various inhibitors and treatment avenues are being developed, to prevent the progression of diabetic complications. In this chapter, we discuss the role of glycation in insulin resistance and further its impact on the kidney.
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Affiliation(s)
- Kirti Parwani
- Department of Biological Sciences, P. D. Patel Institute of Applied Sciences, Charotar University of Science & Technology, Gujarat, India
| | - Palash Mandal
- Department of Biological Sciences, P. D. Patel Institute of Applied Sciences, Charotar University of Science & Technology, Gujarat, India.
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3
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Kikuchi H, Chou CL, Yang CR, Chen L, Jung HJ, Park E, Limbutara K, Carter B, Yang ZH, Kun JF, Remaley AT, Knepper MA. Signaling mechanisms in renal compensatory hypertrophy revealed by multi-omics. Nat Commun 2023; 14:3481. [PMID: 37328470 PMCID: PMC10276015 DOI: 10.1038/s41467-023-38958-9] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/13/2022] [Accepted: 05/24/2023] [Indexed: 06/18/2023] Open
Abstract
Loss of a kidney results in compensatory growth of the remaining kidney, a phenomenon of considerable clinical importance. However, the mechanisms involved are largely unknown. Here, we use a multi-omic approach in a unilateral nephrectomy model in male mice to identify signaling processes associated with renal compensatory hypertrophy, demonstrating that the lipid-activated transcription factor peroxisome proliferator-activated receptor alpha (PPARα) is an important determinant of proximal tubule cell size and is a likely mediator of compensatory proximal tubule hypertrophy.
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Affiliation(s)
- Hiroaki Kikuchi
- Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA.
| | - Chung-Lin Chou
- Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Chin-Rang Yang
- Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Lihe Chen
- Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Hyun Jun Jung
- Division of Nephrology, Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Euijung Park
- Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Kavee Limbutara
- The Center of Excellence in Systems Biology, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | - Benjamin Carter
- Laboratory of Epigenome Biology, Systems Biology Center, National Heart, Lung and Blood Institute, NIH, Bethesda, MD, USA
| | - Zhi-Hong Yang
- Lipoprotein Metabolism Section, Translational Vascular Medicine Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Julia F Kun
- Lipoprotein Metabolism Section, Translational Vascular Medicine Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Alan T Remaley
- Lipoprotein Metabolism Section, Translational Vascular Medicine Branch, National Heart, Lung and Blood Institute, National Institutes of Health, Bethesda, MD, USA
| | - Mark A Knepper
- Epithelial Systems Biology Laboratory, Systems Biology Center, National Heart, Lung, and Blood Institute, National Institutes of Health, Bethesda, MD, USA.
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4
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Kim YC, Fattah H, Fu Y, Nespoux J, Vallon V. Expression of leptin receptor in renal tubules is sparse but implicated in leptin-dependent kidney gene expression and function. Am J Physiol Renal Physiol 2023; 324:F544-F557. [PMID: 37102688 PMCID: PMC10228677 DOI: 10.1152/ajprenal.00279.2022] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Revised: 03/30/2023] [Accepted: 04/16/2023] [Indexed: 04/28/2023] Open
Abstract
Leptin regulates energy balance via leptin receptors expressed in central and peripheral tissues, but little is known about leptin-sensitive kidney genes and the role of the tubular leptin receptor (Lepr) in response to a high-fat diet (HFD). Quantitative RT-PCR analysis of Lepr splice variants A, B, and C revealed a ratio of ∼100:10:1 in the mouse kidney cortex and medulla, with medullary levels being ∼10 times higher. Leptin replacement in ob/ob mice for 6 days reduced hyperphagia, hyperglycemia, and albuminuria, associated with normalization of kidney mRNA expression of molecular markers of glycolysis, gluconeogenesis, amino acid synthesis, and megalin. Normalization of leptin for 7 h in ob/ob mice did not normalize hyperglycemia or albuminuria. Tubular knockdown of Lepr [Pax8-Lepr knockout (KO)] and in situ hybridization revealed a minor fraction of Lepr mRNA in tubular cells compared with endothelial cells. Nevertheless, Pax8-Lepr KO mice had lower kidney weight. Moreover, while HFD-induced hyperleptinemia, increases in kidney weight and glomerular filtration rate, and a modest blood pressure lowering effect were similar compared with controls, they showed a blunted rise in albuminuria. Use of Pax8-Lepr KO and leptin replacement in ob/ob mice identified acetoacetyl-CoA synthetase and gremlin 1 as tubular Lepr-sensitive genes that are increased and reduced by leptin, respectively. In conclusion, leptin deficiency may increase albuminuria via systemic metabolic effects that impinge on kidney megalin expression, whereas hyperleptinemia may induce albuminuria by direct tubular Lepr effects. Implications of Lepr variants and the novel tubular Lepr/acetoacetyl-CoA synthetase/gremlin 1 axis remain to be determined.NEW & NOTEWORTHY This study provides new insights into kidney gene expression of leptin receptor splice variants, leptin-sensitive kidney gene expression, and the role of the leptin receptor in renal tubular cells for the response to diet-induced hyperleptinemia and obesity including albuminuria.
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Affiliation(s)
- Young Chul Kim
- Division of Nephrology and Hypertension, Department of Medicine, University of California-San Diego, La Jolla, California, United States
- Veterans Affairs San Diego Healthcare System, San Diego, California, United States
| | - Hadi Fattah
- Division of Nephrology and Hypertension, Department of Medicine, University of California-San Diego, La Jolla, California, United States
- Veterans Affairs San Diego Healthcare System, San Diego, California, United States
| | - Yiling Fu
- Veterans Affairs San Diego Healthcare System, San Diego, California, United States
| | - Josselin Nespoux
- Veterans Affairs San Diego Healthcare System, San Diego, California, United States
| | - Volker Vallon
- Division of Nephrology and Hypertension, Department of Medicine, University of California-San Diego, La Jolla, California, United States
- Veterans Affairs San Diego Healthcare System, San Diego, California, United States
- Department of Pharmacology, University of California-San Diego, La Jolla, California, United States
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5
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Schaub JA, AlAkwaa FM, McCown PJ, Naik AS, Nair V, Eddy S, Menon R, Otto EA, Demeke D, Hartman J, Fermin D, O’Connor CL, Subramanian L, Bitzer M, Harned R, Ladd P, Pyle L, Pennathur S, Inoki K, Hodgin JB, Brosius FC, Nelson RG, Kretzler M, Bjornstad P. SGLT2 inhibitors mitigate kidney tubular metabolic and mTORC1 perturbations in youth-onset type 2 diabetes. J Clin Invest 2023; 133:e164486. [PMID: 36637914 PMCID: PMC9974101 DOI: 10.1172/jci164486] [Citation(s) in RCA: 20] [Impact Index Per Article: 20.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Accepted: 12/20/2022] [Indexed: 01/14/2023] Open
Abstract
The molecular mechanisms of sodium-glucose cotransporter-2 (SGLT2) inhibitors (SGLT2i) remain incompletely understood. Single-cell RNA sequencing and morphometric data were collected from research kidney biopsies donated by young persons with type 2 diabetes (T2D), aged 12 to 21 years, and healthy controls (HCs). Participants with T2D were obese and had higher estimated glomerular filtration rates and mesangial and glomerular volumes than HCs. Ten T2D participants had been prescribed SGLT2i (T2Di[+]) and 6 not (T2Di[-]). Transcriptional profiles showed SGLT2 expression exclusively in the proximal tubular (PT) cluster with highest expression in T2Di(-) patients. However, transcriptional alterations with SGLT2i treatment were seen across nephron segments, particularly in the distal nephron. SGLT2i treatment was associated with suppression of transcripts in the glycolysis, gluconeogenesis, and tricarboxylic acid cycle pathways in PT, but had the opposite effect in thick ascending limb. Transcripts in the energy-sensitive mTORC1-signaling pathway returned toward HC levels in all tubular segments in T2Di(+), consistent with a diabetes mouse model treated with SGLT2i. Decreased levels of phosphorylated S6 protein in proximal and distal tubules in T2Di(+) patients confirmed changes in mTORC1 pathway activity. We propose that SGLT2i treatment benefits the kidneys by mitigating diabetes-induced metabolic perturbations via suppression of mTORC1 signaling in kidney tubules.
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Affiliation(s)
| | | | | | | | - Viji Nair
- Department of Internal Medicine, Division of Nephrology
| | - Sean Eddy
- Department of Internal Medicine, Division of Nephrology
| | - Rajasree Menon
- Department of Computational Medicine and Bioinformatics, and
| | - Edgar A. Otto
- Department of Internal Medicine, Division of Nephrology
| | - Dawit Demeke
- Department of Pathology, University of Michigan, Ann Arbor, Michigan, USA
| | - John Hartman
- Department of Internal Medicine, Division of Nephrology
| | - Damian Fermin
- Department of Internal Medicine, Division of Nephrology
| | | | | | - Markus Bitzer
- Department of Internal Medicine, Division of Nephrology
| | | | | | - Laura Pyle
- Department of Biostatistics and Informatics, and
- Department of Pediatrics, Section of Endocrinology, University of Colorado School of Medicine, Aurora, Colorado, USA
| | - Subramaniam Pennathur
- Department of Internal Medicine, Division of Nephrology
- Department of Molecular and Integrative Physiology and
| | - Ken Inoki
- Department of Internal Medicine, Division of Nephrology
- Department of Molecular and Integrative Physiology and
- Life Sciences Institute, University of Michigan, Ann Arbor, Michigan, USA
| | - Jeffrey B. Hodgin
- Department of Pathology, University of Michigan, Ann Arbor, Michigan, USA
| | - Frank C. Brosius
- Department of Internal Medicine, Division of Nephrology
- Division of Nephrology, The University of Arizona College of Medicine Tucson, Tucson, Arizona, USA
| | - Robert G. Nelson
- Chronic Kidney Disease Section, National Institute of Diabetes and Digestive and Kidney Diseases (NIDDK), Phoenix, Arizona, USA
| | - Matthias Kretzler
- Department of Internal Medicine, Division of Nephrology
- Department of Computational Medicine and Bioinformatics, and
| | - Petter Bjornstad
- Department of Pediatrics, Section of Endocrinology, University of Colorado School of Medicine, Aurora, Colorado, USA
- Department of Medicine, Division of Renal Diseases and Hypertension, University of Colorado School of Medicine, Aurora, Colorado, USA
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6
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Huynh C, Ryu J, Lee J, Inoki A, Inoki K. Nutrient-sensing mTORC1 and AMPK pathways in chronic kidney diseases. Nat Rev Nephrol 2023; 19:102-122. [PMID: 36434160 DOI: 10.1038/s41581-022-00648-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/20/2022] [Indexed: 11/27/2022]
Abstract
Nutrients such as glucose, amino acids and lipids are fundamental sources for the maintenance of essential cellular processes and homeostasis in all organisms. The nutrient-sensing kinases mechanistic target of rapamycin (mTOR) and AMP-activated protein kinase (AMPK) are expressed in many cell types and have key roles in the control of cell growth, proliferation, differentiation, metabolism and survival, ultimately contributing to the physiological development and functions of various organs, including the kidney. Dysregulation of these kinases leads to many human health problems, including cancer, neurodegenerative diseases, metabolic disorders and kidney diseases. In the kidney, physiological levels of mTOR and AMPK activity are required to support kidney cell growth and differentiation and to maintain kidney cell integrity and normal nephron function, including transport of electrolytes, water and glucose. mTOR forms two functional multi-protein kinase complexes, mTOR complex 1 (mTORC1) and mTOR complex 2 (mTORC2). Hyperactivation of mTORC1 leads to podocyte and tubular cell dysfunction and vulnerability to injury, thereby contributing to the development of chronic kidney diseases, including diabetic kidney disease, obesity-related kidney disease and polycystic kidney disease. Emerging evidence suggests that targeting mTOR and/or AMPK could be an effective therapeutic approach to controlling or preventing these diseases.
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Affiliation(s)
- Christopher Huynh
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA.,Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Jaewhee Ryu
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Jooho Lee
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA
| | - Ayaka Inoki
- Department of Biology, Johns Hopkins University, Baltimore, MD, USA.,Department of Internal Medicine, Division of Nephrology, University of Michigan Medical School, Ann Arbor, MI, USA
| | - Ken Inoki
- Life Sciences Institute, University of Michigan, Ann Arbor, MI, USA. .,Department of Molecular and Integrative Physiology, University of Michigan Medical School, Ann Arbor, MI, USA. .,Department of Internal Medicine, Division of Nephrology, University of Michigan Medical School, Ann Arbor, MI, USA.
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7
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Beyond controlling cell size: functional analyses of S6K in tumorigenesis. Cell Death Dis 2022; 13:646. [PMID: 35879299 PMCID: PMC9314331 DOI: 10.1038/s41419-022-05081-4] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/06/2022] [Revised: 07/05/2022] [Accepted: 07/07/2022] [Indexed: 01/21/2023]
Abstract
As a substrate and major effector of the mammalian target of rapamycin complex 1 (mTORC1), the biological functions of ribosomal protein S6 kinase (S6K) have been canonically assigned for cell size control by facilitating mRNA transcription, splicing, and protein synthesis. However, accumulating evidence implies that diverse stimuli and upstream regulators modulate S6K kinase activity, leading to the activation of a plethora of downstream substrates for distinct pathobiological functions. Beyond controlling cell size, S6K simultaneously plays crucial roles in directing cell apoptosis, metabolism, and feedback regulation of its upstream signals. Thus, we comprehensively summarize the emerging upstream regulators, downstream substrates, mouse models, clinical relevance, and candidate inhibitors for S6K and shed light on S6K as a potential therapeutic target for cancers.
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8
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Li F, Fang Y, Zhuang Q, Cheng M, Moronge D, Jue H, Meyuhas O, Ding X, Zhang Z, Chen JK, Wu H. Blocking ribosomal protein S6 phosphorylation inhibits podocyte hypertrophy and focal segmental glomerulosclerosis. Kidney Int 2022; 102:121-135. [PMID: 35483522 PMCID: PMC10711420 DOI: 10.1016/j.kint.2022.02.037] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2021] [Revised: 02/01/2022] [Accepted: 02/17/2022] [Indexed: 10/18/2022]
Abstract
Ribosomal protein S6 (rpS6) phosphorylation mediates the hypertrophic growth of kidney proximal tubule cells. However, the role of rpS6 phosphorylation in podocyte hypertrophy and podocyte loss during the pathogenesis of focal segmental glomerulosclerosis (FSGS) remains undefined. Here, we examined rpS6 phosphorylation levels in kidney biopsy specimens from patients with FSGS and in podocytes from mouse kidneys with Adriamycin-induced FSGS. Using genetic and pharmacologic approaches in the mouse model of FSGS, we investigated the role of rpS6 phosphorylation in podocyte hypertrophy and loss during development and progression of FSGS. Phosphorylated rpS6 was found to be markedly increased in the podocytes of patients with FSGS and Adriamycin-induced FSGS mice. Genetic deletion of the Tuberous sclerosis 1 gene in kidney glomerular podocytes activated mammalian target of rapamycin complex 1 signaling to rpS6 phosphorylation, resulting in podocyte hypertrophy and pathologic features similar to those of patients with FSGS including podocyte loss, leading to segmental glomerulosclerosis. Since protein phosphatase 1 is known to negatively regulate rpS6 phosphorylation, treatment with an inhibitor increased phospho-rpS6 levels, promoted podocyte hypertrophy and exacerbated formation of FSGS lesions. Importantly, blocking rpS6 phosphorylation (either by generating congenic rpS6 knock-in mice expressing non-phosphorylatable rpS6 or by inhibiting ribosomal protein S6 kinase 1-mediated rpS6 phosphorylation with an inhibitor) significantly blunted podocyte hypertrophy, inhibited podocyte loss, and attenuated formation of FSGS lesions. Thus, our study provides genetic and pharmacologic evidence indicating that specifically targeting rpS6 phosphorylation can attenuate the development of FSGS lesions by inhibiting podocyte hypertrophy and associated podocyte depletion.
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Affiliation(s)
- Fang Li
- Department of Pathology, School of Basic Medical Sciences, Fudan University, Shanghai, China; Department of Nephrology, Zhongshan Hospital, Fudan University, Shanghai, China; Department of Cellular Biology and Anatomy Medical College of Georgia, Augusta University, Augusta, Georgia, USA; Department of Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Yili Fang
- Department of Pathology, School of Basic Medical Sciences, Fudan University, Shanghai, China; Department of Nephrology, Shanghai General Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | - Qiyuan Zhuang
- Department of Pathology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Meichu Cheng
- Department of Cellular Biology and Anatomy Medical College of Georgia, Augusta University, Augusta, Georgia, USA; Department of Nephrology, Second Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Desmond Moronge
- Department of Cellular Biology and Anatomy Medical College of Georgia, Augusta University, Augusta, Georgia, USA; Department of Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Hao Jue
- Department of Pathology, School of Basic Medical Sciences, Fudan University, Shanghai, China
| | - Oded Meyuhas
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada, Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Xiaoqiang Ding
- Department of Nephrology, Zhongshan Hospital, Fudan University, Shanghai, China
| | - Zhigang Zhang
- Department of Pathology, School of Basic Medical Sciences, Fudan University, Shanghai, China.
| | - Jian-Kang Chen
- Department of Cellular Biology and Anatomy Medical College of Georgia, Augusta University, Augusta, Georgia, USA; Department of Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia, USA
| | - Huijuan Wu
- Department of Pathology, School of Basic Medical Sciences, Fudan University, Shanghai, China.
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9
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Abstract
The functional mass of kidney tissue in an adult is an important determinant of human health. Kidney formation during development is an essential determinant of the final nephron endowment of the adult organ, and no evidence has been reported that mice or humans are able to generate new nephrons after the developmental period. Mechanisms controlling organ growth after development are essential to establish the final adult organ size. The potential for organ growth is maintained in adult life and the size of one kidney may be significantly increased by loss of the contralateral kidney. The mouse has provided a model system for investigators to critically explore genetic, cell biological, and hormonal control of developmental and juvenile kidney growth. This article reviews three basic aspects of kidney size regulation: (1) Mechanisms that control nephron formation and how these are altered by the cessation of nephrogenesis at the end of the developmental period. (2) Applicability of the general model for growth hormone-insulin like growth factor control to kidney growth both pre- and postnatally. (3) Commonalities between mechanisms of juvenile kidney growth and the compensatory growth that is stimulated in adult life by reduction of kidney mass. Understanding the mechanisms that determine set-points for cell numbers and size in the kidney may inform ongoing efforts to generate kidney tissue from stem cells.
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Affiliation(s)
- Leif Oxburgh
- The Rogosin Institute, New York, NY, United States.
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10
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Laouari D, Vergnaud P, Hirose T, Zaidan M, Rabant M, Nguyen C, Burtin M, Legendre C, Codogno P, Friedlander G, Anglicheau D, Terzi F. The sexual dimorphism of kidney growth in mice and humans. Kidney Int 2022; 102:78-95. [PMID: 35337891 DOI: 10.1016/j.kint.2022.02.027] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2021] [Revised: 02/02/2022] [Accepted: 02/16/2022] [Indexed: 10/18/2022]
Abstract
Kidney mass and function are sexually determined, but the cellular events and the molecular mechanisms involved in this dimorphism are poorly characterized. By combining female and male mice with castration/replacement experiments, we showed that male mice exhibited kidney overgrowth from five weeks of age. This effect was organ specific, since liver and heart weight were comparable between males and females, regardless of age. Consistently, the androgen receptor was found to be expressed in the kidneys of males, but not in the liver. In growing mice, androgens led to kidney overgrowth by first inducing a burst of cell proliferation and then an increase of cell size. Remarkably, androgens were also required to maintain cell size in adults. In fact, orchiectomy resulted in smaller kidneys in a matter of few weeks. These changes paralleled the changes of the expression of ornithine decarboxylase and cyclin D1, two known mediators of kidney growth, whereas, unexpectedly, mTORC1 and Hippo pathways did not seem to be involved. Androgens also enhanced kidney autophagy, very likely by increasing transcription factor EB nuclear translocation. Functionally, the increase of tubular mass resulted in increased sodium/phosphate transport. These findings were relevant to humans. Remarkably, by studying living gender-paired kidney donors-recipients, we showed that tubular cell size increased three months after transplantation in men as compared to women, regardless of the donor gender. Thus, our results identify novel signaling pathways that may be involved in androgen-induced kidney growth and homeostasis, and suggest that androgens determine kidney size after transplantation.
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Affiliation(s)
- Denise Laouari
- Université de Paris, INSERM U1151, CNRS UMR 8253, Institut Necker Enfants Malades (INEM), Département « Croissance et Signalisation », F-75006 Paris, France
| | - Paul Vergnaud
- Université de Paris, INSERM U1151, CNRS UMR 8253, Institut Necker Enfants Malades (INEM), Département « Croissance et Signalisation », F-75006 Paris, France; Service de Néphrologie Pédiatrique-Hémodialyse-Transplantation, AP-HP, Hôpital Necker, Paris, France
| | - Takuo Hirose
- Université de Paris, INSERM U1151, CNRS UMR 8253, Institut Necker Enfants Malades (INEM), Département « Croissance et Signalisation », F-75006 Paris, France
| | - Mohamad Zaidan
- Université de Paris, INSERM U1151, CNRS UMR 8253, Institut Necker Enfants Malades (INEM), Département « Croissance et Signalisation », F-75006 Paris, France; Service de Néphrologie-Transplantation, AP-HP, Hôpital Bicêtre, Le Kremlin-Bicêtre, France
| | - Marion Rabant
- Université de Paris, INSERM U1151, CNRS UMR 8253, Institut Necker Enfants Malades (INEM), Département « Croissance et Signalisation », F-75006 Paris, France; Service d'Anatomo-Pathologie, AP-HP, Hôpital Necker, Paris, France
| | - Clément Nguyen
- Université de Paris, INSERM U1151, CNRS UMR 8253, Institut Necker Enfants Malades (INEM), Département « Croissance et Signalisation », F-75006 Paris, France
| | - Martine Burtin
- Université de Paris, INSERM U1151, CNRS UMR 8253, Institut Necker Enfants Malades (INEM), Département « Croissance et Signalisation », F-75006 Paris, France
| | - Christophe Legendre
- Université de Paris, INSERM U1151, CNRS UMR 8253, Institut Necker Enfants Malades (INEM), Département « Croissance et Signalisation », F-75006 Paris, France; Service de Néphrologie-Transplantation, AP-HP, Hôpital Necker, Paris, France
| | - Patrice Codogno
- Université de Paris, INSERM U1151, CNRS UMR 8253, Institut Necker Enfants Malades (INEM), Département « Croissance et Signalisation », F-75006 Paris, France
| | - Gerard Friedlander
- Université de Paris, INSERM U1151, CNRS UMR 8253, Institut Necker Enfants Malades (INEM), Département « Croissance et Signalisation », F-75006 Paris, France
| | - Dany Anglicheau
- Université de Paris, INSERM U1151, CNRS UMR 8253, Institut Necker Enfants Malades (INEM), Département « Croissance et Signalisation », F-75006 Paris, France; Service de Néphrologie-Transplantation, AP-HP, Hôpital Necker, Paris, France
| | - Fabiola Terzi
- Université de Paris, INSERM U1151, CNRS UMR 8253, Institut Necker Enfants Malades (INEM), Département « Croissance et Signalisation », F-75006 Paris, France.
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11
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Avagimyan A. THE PATHOPHYSIOLOGICAL BASIS OF DIABETIC CARDIOMYOPATHY DEVELOPMENT. Curr Probl Cardiol 2022; 47:101156. [DOI: 10.1016/j.cpcardiol.2022.101156] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2022] [Accepted: 02/16/2022] [Indexed: 01/02/2023]
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12
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Brown CN, Atwood D, Pokhrel D, Holditch SJ, Altmann C, Skrypnyk NI, Bourne J, Klawitter J, Blaine J, Faubel S, Thorburn A, Edelstein CL. Surgical procedures suppress autophagic flux in the kidney. Cell Death Dis 2021; 12:248. [PMID: 33674554 PMCID: PMC7935862 DOI: 10.1038/s41419-021-03518-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Revised: 02/02/2021] [Accepted: 02/09/2021] [Indexed: 02/08/2023]
Abstract
Many surgical models are used to study kidney and other diseases in mice, yet the effects of the surgical procedure itself on the kidney and other tissues have not been elucidated. In the present study, we found that both sham surgery and unilateral nephrectomy (UNX), which is used as a model of renal compensatory hypertrophy, in mice resulted in increased mammalian target of rapamycin complex 1/2 (mTORC1/2) in the remaining kidney. mTORC1 is known to regulate lysosomal biogenesis and autophagy. Genes associated with lysosomal biogenesis and function were decreased in sham surgery and UNX kidneys. In both sham surgery and UNX, there was suppressed autophagic flux in the kidney as indicated by the lack of an increase in LC3-II or autophagosomes seen on immunoblot, IF and EM after bafilomycin A1 administration and a concomitant increase in p62, a marker of autophagic cargo. There was a massive increase in pro-inflammatory cytokines, which are known to activate ERK1/2, in the serum after sham surgery and UNX. There was a large increase in ERK1/2 in sham surgery and UNX kidneys, which was blocked by the MEK1/2 inhibitor, trametinib. Trametinib also resulted in a significant decrease in p62. In summary, there was an intense systemic inflammatory response, an ERK-mediated increase in p62 and suppressed autophagic flux in the kidney after sham surgery and UNX. It is important that researchers are aware that changes in systemic pro-inflammatory cytokines, ERK1/2 and autophagy can be caused by sham surgery as well as the kidney injury/disease itself.
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Affiliation(s)
- Carolyn N Brown
- Division of Renal Diseases and Hypertension, University of Colorado at Denver, Aurora, CO, USA
| | - Daniel Atwood
- Division of Renal Diseases and Hypertension, University of Colorado at Denver, Aurora, CO, USA
| | - Deepak Pokhrel
- Division of Renal Diseases and Hypertension, University of Colorado at Denver, Aurora, CO, USA
| | - Sara J Holditch
- Division of Renal Diseases and Hypertension, University of Colorado at Denver, Aurora, CO, USA
| | - Christopher Altmann
- Division of Renal Diseases and Hypertension, University of Colorado at Denver, Aurora, CO, USA
| | - Nataliya I Skrypnyk
- Division of Renal Diseases and Hypertension, University of Colorado at Denver, Aurora, CO, USA
| | - Jennifer Bourne
- Electron Microscopy Center, University of Colorado at Denver, Aurora, CO, USA
| | - Jelena Klawitter
- Division of Renal Diseases and Hypertension, University of Colorado at Denver, Aurora, CO, USA
- Department of Anesthesiology, University of Colorado at Denver, Aurora, CO, USA
| | - Judith Blaine
- Division of Renal Diseases and Hypertension, University of Colorado at Denver, Aurora, CO, USA
| | - Sarah Faubel
- Division of Renal Diseases and Hypertension, University of Colorado at Denver, Aurora, CO, USA
| | - Andrew Thorburn
- Department of Pharmacology, University of Colorado at Denver, Aurora, CO, USA
| | - Charles L Edelstein
- Division of Renal Diseases and Hypertension, University of Colorado at Denver, Aurora, CO, USA.
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13
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Kajiwara K, Yamano S, Aoki K, Okuzaki D, Matsumoto K, Okada M. CDCP1 promotes compensatory renal growth by integrating Src and Met signaling. Life Sci Alliance 2021; 4:4/4/e202000832. [PMID: 33574034 PMCID: PMC7893822 DOI: 10.26508/lsa.202000832] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Revised: 01/07/2021] [Accepted: 01/19/2021] [Indexed: 12/15/2022] Open
Abstract
CDCP1 promotes HGF-induced compensatory renal growth by focally and temporally integrating Src and Met-STAT3 signaling in lipid rafts. Compensatory growth of organs after loss of their mass and/or function is controlled by hepatocyte growth factor (HGF), but the underlying regulatory mechanisms remain elusive. Here, we show that CUB domain-containing protein 1 (CDCP1) promotes HGF-induced compensatory renal growth. Using canine kidney cells as a model of renal tubules, we found that HGF-induced temporal up-regulation of Src activity and its scaffold protein, CDCP1, and that the ablation of CDCP1 robustly abrogated HGF-induced phenotypic changes, such as morphological changes and cell growth/proliferation. Mechanistic analyses revealed that up-regulated CDCP1 recruits Src into lipid rafts to activate STAT3 associated with the HGF receptor Met, and activated STAT3 induces the expression of matrix metalloproteinases and mitogenic factors. After unilateral nephrectomy in mice, the Met-STAT3 signaling is transiently up-regulated in the renal tubules of the remaining kidney, whereas CDCP1 ablation attenuates regenerative signaling and significantly suppresses compensatory growth. These findings demonstrate that CDCP1 plays a crucial role in controlling compensatory renal growth by focally and temporally integrating Src and Met signaling.
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Affiliation(s)
- Kentaro Kajiwara
- Department of Oncogene Research, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Shotaro Yamano
- Japan Bioassay Research Center, Japan Organization of Occupational Health and Safety, Kanagawa, Japan
| | - Kazuhiro Aoki
- Division of Quantitative Biology, Okazaki Institute for Integrative Bioscience, National Institute for Basic Biology, National Institutes of Natural Sciences, Aichi, Japan
| | - Daisuke Okuzaki
- Genome Information Research Center, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Kunio Matsumoto
- Division of Tumor Dynamics and Regulation, Cancer Research Institute, Kanazawa University, Kanazawa, Japan
| | - Masato Okada
- Department of Oncogene Research, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
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14
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Fang Y, Li F, Qi C, Mao X, Wang F, Zhao Z, Chen JK, Zhang Z, Wu H. Metformin effectively treats Tsc1 deletion-caused kidney pathology by upregulating AMPK phosphorylation. Cell Death Discov 2020; 6:52. [PMID: 32566257 PMCID: PMC7295815 DOI: 10.1038/s41420-020-0285-0] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Revised: 05/18/2020] [Accepted: 05/28/2020] [Indexed: 12/25/2022] Open
Abstract
Tuberous sclerosis complex (TSC) is characterized by hamartomatous lesions in multiple organs, with most patients developing polycystic kidney disease and leading to a decline of renal function. TSC is caused by loss-of-function mutations in either Tsc1 or Tsc2 gene, but currently, there is no effective treatment for aberrant kidney growth in TSC patients. By generating a renal proximal tubule-specific Tsc1 gene-knockout (Tsc1 ptKO) mouse model, we observed that Tsc1 ptKO mice developed aberrantly enlarged kidneys primarily due to hypertrophy and proliferation of proximal tubule cells, along with some cystogenesis, interstitial inflammation, and fibrosis. Mechanistic studies revealed inhibition of AMP-activated protein kinase (AMPK) phosphorylation at Thr-172 and activation of Akt phosphorylation at Ser-473 and Thr-308. We therefore treated Tsc1 ptKO mice with the AMPK activator, metformin, by daily intraperitoneal injection. Our results indicated that metformin increased the AMPK phosphorylation, but decreased the Akt phosphorylation. These signaling modulations resulted in inhibition of proliferation and induction of apoptosis in the renal proximal tubule cells of Tsc1 ptKO mice. Importantly, metformin treatment effectively prevented aberrant kidney enlargement and cyst growth, inhibited inflammatory response, attenuated interstitial fibrosis, and protected renal function. The effects of metformin were further confirmed by in vitro experiments. In conclusion, this study indicates a potential therapeutic effect of metformin on Tsc1 deletion-induced kidney pathology, although currently metformin is primarily prescribed to treat patients with type 2 diabetes.
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Affiliation(s)
- Yili Fang
- Department of Pathology, School of Basic Medical Science, Fudan University, Shanghai, 200032 PR China
| | - Fang Li
- Department of Pathology, School of Basic Medical Science, Fudan University, Shanghai, 200032 PR China
| | - Chenyang Qi
- Department of Pathology, School of Basic Medical Science, Fudan University, Shanghai, 200032 PR China
| | - Xing Mao
- Department of Pathology, School of Basic Medical Science, Fudan University, Shanghai, 200032 PR China
| | - Feng Wang
- Department of Nephrology, Shanghai 6th People’s Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, 200032 PR China
| | - Zhonghua Zhao
- Department of Pathology, School of Basic Medical Science, Fudan University, Shanghai, 200032 PR China
| | - Jian-Kang Chen
- Department of Cellular Biology & Anatomy, Medical College of Georgia, Augusta University, Augusta, GA 30912 USA
| | - Zhigang Zhang
- Department of Pathology, School of Basic Medical Science, Fudan University, Shanghai, 200032 PR China
| | - Huijuan Wu
- Department of Pathology, School of Basic Medical Science, Fudan University, Shanghai, 200032 PR China
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15
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Liu T, Yuan J, Dai C, Xu J, Li S, Humphreys BD, Kleven DT, Chen JK. Cre/loxP approach-mediated downregulation of Pik3c3 inhibits the hypertrophic growth of renal proximal tubule cells. J Cell Physiol 2020; 235:9958-9973. [PMID: 32474911 DOI: 10.1002/jcp.29811] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2019] [Revised: 04/21/2020] [Accepted: 05/13/2020] [Indexed: 11/08/2022]
Abstract
Nephron loss stimulates residual functioning nephrons to undergo compensatory growth. Excessive nephron growth may be a maladaptive response that sets the stage for progressive nephron damage, leading to kidney failure. To date, however, the mechanism of nephron growth remains incompletely understood. Our previous study revealed that class III phosphatidylinositol-3-kinase (Pik3c3) is activated in the remaining kidney after unilateral nephrectomy (UNX)-induced nephron loss, but previous studies failed to generate a Pik3c3 gene knockout animal model. Global Pik3c3 deletion results in embryonic lethality. Given that renal proximal tubule cells make up the bulk of the kidney and undergo the most prominent hypertrophic growth after UNX, in this study we used Cre-loxP-based approaches to demonstrate for the first time that tamoxifen-inducible SLC34a1 promoter-driven CreERT2 recombinase-mediated downregulation of Pik3c3 expression in renal proximal tubule cells alone is sufficient to inhibit UNX- or amino acid-induced hypertrophic nephron growth. Furthermore, our mechanistic studies unveiled that the SLC34a1-CreERT2 recombinase-mediated Pik3c3 downregulation inhibited UNX- or amino acid-stimulated lysosomal localization and signaling activation of mechanistic target of rapamycin complex 1 (mTORC1) in the renal proximal tubules. Moreover, our additional cell culture experiments using RNAi confirmed that knocking down Pik3c3 expression inhibited amino acid-stimulated mTORC1 signaling and blunted cellular growth in primary cultures of renal proximal tubule cells. Together, both our in vivo and in vitro experimental results indicate that Pik3c3 is a major mechanistic mediator responsible for sensing amino acid availability and initiating hypertrophic growth of renal proximal tubule cells by activation of the mTORC1-S6K1-rpS6 signaling pathway.
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Affiliation(s)
- Ting Liu
- Departments of Cellular Biology & Anatomy and Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia
| | - Jialing Yuan
- Departments of Cellular Biology & Anatomy and Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia
| | - Caihong Dai
- Departments of Cellular Biology & Anatomy and Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia
| | - Jinxian Xu
- Departments of Cellular Biology & Anatomy and Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia
| | - Shude Li
- Department of Biochemistry & Molecular Biology, School of Basic Medical Sciences, Kunming Medical University, Kunming, Yunnan, China
| | - Benjamin D Humphreys
- Division of Nephrology, Department of Medicine, Washington University School of Medicine in St. Louis, St. Louis, Missouri
| | - Daniel T Kleven
- Department of Pathology, Medical College of Georgia, Augusta University, Augusta, Georgia
| | - Jian-Kang Chen
- Departments of Cellular Biology & Anatomy and Medicine, Medical College of Georgia, Augusta University, Augusta, Georgia
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16
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Khokhar M, Roy D, Modi A, Agarwal R, Yadav D, Purohit P, Sharma P. Perspectives on the role of PTEN in diabetic nephropathy: an update. Crit Rev Clin Lab Sci 2020; 57:470-483. [PMID: 32306805 DOI: 10.1080/10408363.2020.1746735] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
Phosphatase and tensin homolog (PTEN) is a potent tumor suppressor gene that antagonizes the proto-oncogenic phosphatidylinositol 3 kinase (PI3K)/protein kinase B (Akt) signaling pathway and governs basic cellular metabolic processes. Recently, its role in cell growth, metabolism, architecture, and motility as an intramolecular and regulatory mediator has gained widespread research interest as it applies to non-tumorous diseases, such as insulin resistance (IR) and diabetic nephropathy (DN). DN is characterized by renal tubulointerstitial fibrosis (TIF) and epithelial-mesenchymal transition (EMT), and PTEN plays a significant role in the regulation of both. Epigenetics and microRNAs (miRNAs) are novel players in post-transcriptional regulation and research evidence demonstrates that they reduce the expression of PTEN by acting as key regulators of autophagy and TIF through activation of the Akt/mammalian target of rapamycin (mTOR) signaling pathway. These regulatory processes might play an important role in solving the complexities of DN pathogenesis and IR, as well as the therapeutic management of DN with the help of PTEN K27-linked polyubiquitination. Currently, there are no comprehensive reviews citing the role PTEN plays in the development of DN and its regulation via miRNA and epigenetic modifications. The present review explores these facets of PTEN in the pathogenesis of IR and DN.
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Affiliation(s)
- Manoj Khokhar
- Department of Biochemistry, All India Institute of Medical Sciences, Jodhpur, India
| | - Dipayan Roy
- Department of Biochemistry, All India Institute of Medical Sciences, Jodhpur, India
| | - Anupama Modi
- Department of Biochemistry, All India Institute of Medical Sciences, Jodhpur, India
| | - Riddhi Agarwal
- Department of Biochemistry, All India Institute of Medical Sciences, Jodhpur, India
| | - Dharmveer Yadav
- Department of Biochemistry, All India Institute of Medical Sciences, Jodhpur, India
| | - Purvi Purohit
- Department of Biochemistry, All India Institute of Medical Sciences, Jodhpur, India
| | - Praveen Sharma
- Department of Biochemistry, All India Institute of Medical Sciences, Jodhpur, India
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17
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Vallon V, Thomson SC. The tubular hypothesis of nephron filtration and diabetic kidney disease. Nat Rev Nephrol 2020; 16:317-336. [PMID: 32152499 DOI: 10.1038/s41581-020-0256-y] [Citation(s) in RCA: 219] [Impact Index Per Article: 54.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 01/22/2020] [Indexed: 02/08/2023]
Abstract
Kidney size and glomerular filtration rate (GFR) often increase with the onset of diabetes, and elevated GFR is a risk factor for the development of diabetic kidney disease. Hyperfiltration mainly occurs in response to signals passed from the tubule to the glomerulus: high levels of glucose in the glomerular filtrate drive increased reabsorption of glucose and sodium by the sodium-glucose cotransporters SGLT2 and SGLT1 in the proximal tubule. Passive reabsorption of chloride and water also increases. The overall capacity for proximal reabsorption is augmented by growth of the proximal tubule, which (alongside sodium-glucose cotransport) further limits urinary glucose loss. Hyperreabsorption of sodium and chloride induces tubuloglomerular feedback from the macula densa to increase GFR. In addition, sodium-glucose cotransport by SGLT1 on macula densa cells triggers the production of nitric oxide, which also contributes to glomerular hyperfiltration. Although hyperfiltration restores sodium and chloride excretion it imposes added physical stress on the filtration barrier and increases the oxygen demand to drive reabsorption. Tubular growth is associated with the development of a senescence-like molecular signature that sets the stage for inflammation and fibrosis. SGLT2 inhibitors attenuate the proximal reabsorption of sodium and glucose, normalize tubuloglomerular feedback signals and mitigate hyperfiltration. This tubule-centred model of diabetic kidney physiology predicts the salutary effect of SGLT2 inhibitors on hard renal outcomes, as shown in large-scale clinical trials.
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Affiliation(s)
- Volker Vallon
- Division of Nephrology and Hypertension, Department of Medicine, University of California San Diego, La Jolla, CA, USA. .,Department of Pharmacology, University of California San Diego, La Jolla, CA, USA. .,VA San Diego Healthcare System, San Diego, CA, USA.
| | - Scott C Thomson
- Division of Nephrology and Hypertension, Department of Medicine, University of California San Diego, La Jolla, CA, USA.,VA San Diego Healthcare System, San Diego, CA, USA
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18
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Liu T, Dai C, Xu J, Li S, Chen JK. The expression level of class III phosphatidylinositol-3 kinase controls the degree of compensatory nephron hypertrophy. Am J Physiol Renal Physiol 2020; 318:F628-F638. [PMID: 31904289 DOI: 10.1152/ajprenal.00381.2019] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
Excessive compensatory nephron hypertrophy (CNH) has been implicated in setting the stage for progressive nephron damage. Lack of a class III phosphatidylinositol 3-kinase (Pik3c3) inhibitor suitable for using in animals and lack of a Pik3c3-deficient animal model preclude the possibility of conclusively defining a role for Pik3c3 in CNH in previous studies. Here, we report that insertion of an Frt-flanked PGK-Neo cassette into intron 19 of the mouse Pik3c3 gene resulted in a hypomorphic allele. This allowed us to create a unique mouse model and provide the first definitive genetic evidence demonstrating whether Pik3c3 is essential for the regulation of CNH. Our results indicate that homozygous Pik3c3 hypomorphic (Pik3c3Hypo/Hypo) mice express significantly low levels of Pik3c3 than heterozygous Pik3c3 hypomorphic (Pik3c3Hypo/WT) littermates, which already express a lower level of Pik3c3 than wild-type (Pik3c3WT/WT) littermates. Interestingly, after unilateral nephrectomy (UNX), Pik3c3Hypo/Hypo mice develop a significantly lower degree of CNH than Pik3c3WT/WT mice and Pik3c3Hypo/WT mice, as revealed by measurement of kidney weight, kidney-to-body weight ratio, renal protein-to-DNA ratio, and morphometric analysis of proximal tubular and glomerular size. Mechanistically, UNX-induced mammalian target of rapamycin complex 1 (mTORC1) signaling to phosphorylation of ribosomal protein S6 (rpS6) in the remaining kidney was markedly inhibited in Pik3c3 hypomorphic mice. In conclusion, the present study reports a Pik3c3 hypomorphic mouse model and provides the first definitive evidence that Pik3c3 controls the degree of compensatory nephron hypertrophy. In addition, our signaling data provide the first definitive in vivo proof that Pik3c3 functions upstream of the mTORC1-S6 kinase 1-rpS6 pathway in the regulation of compensatory nephron hypertrophy.
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Affiliation(s)
- Ting Liu
- Departments of Cellular Biology and Anatomy and Medicine, Medical College of Georgia, Augusta University, Augusta, Gerogia
| | - Caihong Dai
- Departments of Cellular Biology and Anatomy and Medicine, Medical College of Georgia, Augusta University, Augusta, Gerogia
| | - Jinxian Xu
- Departments of Cellular Biology and Anatomy and Medicine, Medical College of Georgia, Augusta University, Augusta, Gerogia
| | - Shude Li
- Department of Biochemistry and Molecular Biology, School of Basic Medical Sciences, Kunming Medical University, Kunming, Yunnan, China
| | - Jian-Kang Chen
- Departments of Cellular Biology and Anatomy and Medicine, Medical College of Georgia, Augusta University, Augusta, Gerogia
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19
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Rojas-Canales DM, Li JY, Makuei L, Gleadle JM. Compensatory renal hypertrophy following nephrectomy: When and how? Nephrology (Carlton) 2019; 24:1225-1232. [PMID: 30809888 DOI: 10.1111/nep.13578] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/24/2019] [Indexed: 12/16/2022]
Abstract
Following surgical removal of one kidney, the other enlarges and increases its function. The mechanism for the sensing of this change and the growth is incompletely understood but begins within days and compensatory renal hypertrophy (CRH) is the dominant contributor to the growth. In many individuals undergoing nephrectomy for cancer or kidney donation this produces a substantial and helpful increase in renal function. Two main mechanisms have been proposed, one in which increased activity by the remaining kidney leads to hypertrophy, the second in which there is release of a kidney specific factor in response to a unilateral nephrectomy that initiates CRH. Whilst multiple growth factors and pathways such as the mTORC pathway have been implicated in experimental studies, their roles and the precise mechanism of CRH are not defined. Unrestrained hypoxia inducible factor activation in renal cancer promotes growth and may play an important role in driving CRH.
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Affiliation(s)
- Darling M Rojas-Canales
- College of Medicine and Public Health and Medicine, Flinders University, Adelaide, South Australia, Australia.,Department of Renal Medicine, Flinders Medical Centre, Adelaide, South Australia, Australia
| | - Jordan Y Li
- College of Medicine and Public Health and Medicine, Flinders University, Adelaide, South Australia, Australia.,Department of Renal Medicine, Flinders Medical Centre, Adelaide, South Australia, Australia
| | - Leek Makuei
- College of Medicine and Public Health and Medicine, Flinders University, Adelaide, South Australia, Australia
| | - Jonathan M Gleadle
- College of Medicine and Public Health and Medicine, Flinders University, Adelaide, South Australia, Australia.,Department of Renal Medicine, Flinders Medical Centre, Adelaide, South Australia, Australia
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20
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Das F, Maity S, Ghosh-Choudhury N, Kasinath BS, Ghosh Choudhury G. Deacetylation of S6 kinase promotes high glucose-induced glomerular mesangial cell hypertrophy and matrix protein accumulation. J Biol Chem 2019; 294:9440-9460. [PMID: 31028173 DOI: 10.1074/jbc.ra118.007023] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/05/2018] [Revised: 04/09/2019] [Indexed: 12/30/2022] Open
Abstract
S6 kinase acts as a driver for renal hypertrophy and matrix accumulation, two key pathologic signatures of diabetic nephropathy. As a post-translational modification, S6 kinase undergoes acetylation at the C terminus. The role of this acetylation to regulate kidney glomerular cell hypertrophy and matrix expansion is not known. In mesangial cells, high glucose decreased the acetylation and enhanced phosphorylation of S6 kinase and its substrates rps6 and eEF2 kinase that lead to dephosphorylation of eEF2. To determine the mechanism of S6 kinase deacetylation, we found that trichostatin A, a pan-histone deacetylase (HDAC) inhibitor, blocked all high glucose-induced effects. Furthermore, high glucose increased the expression and association of HDAC1 with S6 kinase. HDAC1 decreased the acetylation of S6 kinase and mimicked the effects of high glucose, resulting in mesangial cell hypertrophy and expression of fibronectin and collagen I (α2). In contrast, siRNA against HDAC1 inhibited these effects by high glucose. A C-terminal acetylation-mimetic mutant of S6 kinase suppressed high glucose-stimulated phosphorylation of S6 kinase, rps6 and eEF2 kinase, and inhibited the dephosphorylation of eEF2. Also, the acetylation mimetic attenuated the mesangial cell hypertrophy and fibronectin and collagen I (α2) expression. Conversely, an S6 kinase acetylation-deficient mutant induced all the above effects of high glucose. Finally, in the renal glomeruli of diabetic rats, the acetylation of S6 kinase was significantly reduced concomitant with increased HDAC1 and S6 kinase activity. In aggregate, our data uncovered a previously unrecognized role of S6 kinase deacetylation in high glucose-induced mesangial cell hypertrophy and matrix protein expression.
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Affiliation(s)
| | | | | | | | - Goutam Ghosh Choudhury
- Departments of Medicine and .,Departments of Medicine and.,Geriatric Research, Education and Clinical Center, South Texas Veterans Health Care System, San Antonio, Texas 78229 and
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21
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Chen J, You H, Li Y, Xu Y, He Q, Harris RC. EGF Receptor-Dependent YAP Activation Is Important for Renal Recovery from AKI. J Am Soc Nephrol 2018; 29:2372-2385. [PMID: 30072422 PMCID: PMC6115662 DOI: 10.1681/asn.2017121272] [Citation(s) in RCA: 66] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/11/2017] [Accepted: 06/22/2018] [Indexed: 12/24/2022] Open
Abstract
BACKGROUND Increasing evidence indicates that renal recovery from AKI stems from dedifferentiation and proliferation of surviving tubule epithelial cells. Both EGF receptor (EGFR) and the Hippo signaling pathway are implicated in cell proliferation and differentiation, and previous studies showed that activation of EGFR in renal proximal tubule epithelial cells (RPTCs) plays a critical role in recovery from ischemia-reperfusion injury (IRI). In this study, we explored RPTC activation of Yes-associated protein (YAP) and transcriptional coactivator with PDZ binding motif (TAZ), two key downstream effectors of the Hippo pathway, and their potential involvement in recovery from AKI. METHODS We used immunofluorescence to examine YAP expression in kidney biopsy samples from patients with clinical AKI and controls (patients with minimal change disease). Studies of RPTC activation of YAP and TAZ used cultured human RPTCs that were exposed to hypoxia-reoxygenation as well as knockout mice (with inducible deletions of Yap, Taz, or both occurring specifically in RPTCs) that were subjected to bilateral IRI. RESULTS YAP was activated in RPTCs in kidneys from post-AKI patients and post-IRI mouse kidneys. Inhibition of the interaction of YAP and the TEA domain (TEAD) transcription factor complex by verteporfin or conditional deletion of YAP in RPTCs delayed renal functional and structural recovery from IRI, whereas TAZ deletion had no effect. Activation of the EGFR-PI3K-Akt pathway in response to IRI signaled YAP activation, which promoted cell cycle progression. CONCLUSIONS This study shows that EGFR-PI3K-Akt-dependent YAP activation plays an essential role in mediating epithelial cell regeneration during kidney recovery from AKI.
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Affiliation(s)
- Jianchun Chen
- Department of Veterans Affairs, Nashville, Tennessee; Departments of
- Medicine and
- Vanderbilt Center for Kidney Disease, Nashville, Tennessee
| | - Huaizhou You
- Medicine and
- Division of Nephrology, Huashan Hospital, Fudan University, Shanghai, China; and
| | - Yan Li
- Medicine and
- Division of Nephrology, Shanghai Ninth People's Hospital, Shanghai Jiaotong University School of Medicine, Shanghai, China
| | | | | | - Raymond C Harris
- Department of Veterans Affairs, Nashville, Tennessee; Departments of
- Medicine and
- Vanderbilt Center for Kidney Disease, Nashville, Tennessee
- Molecular Physiology and Biophysics, Vanderbilt University School of Medicine, Nashville, Tennessee
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22
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Fitzgibbon WR, Dang Y, Bunni MA, Baicu CF, Zile MR, Mullick AE, Saigusa T. Attenuation of accelerated renal cystogenesis in Pkd1 mice by renin-angiotensin system blockade. Am J Physiol Renal Physiol 2017; 314:F210-F218. [PMID: 29021226 DOI: 10.1152/ajprenal.00389.2017] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
The intrarenal renin angiotensin system (RAS) is activated in polycystic kidney disease. We have recently shown in the Pkd1 mouse that Gen 2 antisense oligonucleotide (ASO), which suppresses angiotensinogen (Agt) synthesis, is efficacious in slowing kidney cyst formation compared with lisinopril. The aim of this current study was to determine 1) if unilateral nephrectomy accelerates cystogenesis in Pkd1 mice (as previously shown in cilia knockout mice) and 2) whether Agt ASO can slow the progression in this accelerated cystic mouse model. Adult Pkd1 conditional floxed allele mice expressing cre were administered tamoxifen, resulting in global knockout of Pkd1. Three weeks after tamoxifen injection, mice underwent left unilateral nephrectomy. Mice were then treated with Agt ASO (75 mg/kg per week) or aliskiren (20 mg/kg per day)+Agt ASO or control for 8 wk. Unilateral nephrectomy accelerated kidney cyst formation compared with nonnephrectomized mice. Both Agt ASO and Aliskiren+Agt ASO treatments significantly reduced plasma and urinary Agt levels. Blood pressure was lowest in Aliskiren+Agt ASO mice among all treatment groups, and the control group had the highest blood pressure. All mice developed significant kidney cysts at 8 wk after nephrectomy, but Agt ASO and Aliskiren+Agt ASO groups had fewer kidney cysts than controls. Renal pAkt, pS6 levels, and apoptosis were significantly suppressed in those receiving Agt ASO compared with controls. These results indicate that suppressing Agt using an ASO slowed the progression of accelerated cystic kidney disease induced by unilateral nephrectomy in Pkd1 mice by suppressing intrarenal RAS, mammalian target of rapamycin pathway, and cell proliferation.
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Affiliation(s)
- Wayne R Fitzgibbon
- Divison of Nephrology, Medical University of South Carolina , Charleston, South Carolina
| | - Yujing Dang
- Divison of Nephrology, Medical University of South Carolina , Charleston, South Carolina
| | - Marlene A Bunni
- Divison of Nephrology, Medical University of South Carolina , Charleston, South Carolina
| | - Catalin F Baicu
- Division of Cardiology, Medical University of South Carolina, Ralph H. Johnson Veterans Affairs Medical Center , Charleston, South Carolina
| | - Michael R Zile
- Division of Cardiology, Medical University of South Carolina, Ralph H. Johnson Veterans Affairs Medical Center , Charleston, South Carolina
| | | | - Takamitsu Saigusa
- Divison of Nephrology, Medical University of South Carolina , Charleston, South Carolina.,Division of Nephrology, University of Alabama at Birmingham , Birmingham, Alabama
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23
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Whaley-Connell A, Sowers JR. Insulin Resistance in Kidney Disease: Is There a Distinct Role Separate from That of Diabetes or Obesity? Cardiorenal Med 2017; 8:41-49. [PMID: 29344025 DOI: 10.1159/000479801] [Citation(s) in RCA: 59] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Insulin resistance is a central component of the metabolic dysregulation observed in obesity, which puts one at risk for the development of type 2 diabetes and complications related to diabetes such as chronic kidney disease. Insulin resistance and compensatory hyperinsulinemia place one at risk for other risk factors such as dyslipidemia, hypertension, and proteinuria, e.g., development of kidney disease. Our traditional view of insulin actions focuses on insulin-sensitive tissues such as skeletal muscle, liver, adipose tissue, and the pancreas. However, insulin also has distinct actions in kidney tissue that regulate growth, hypertrophy, as well as microcirculatory and fibrotic pathways which, in turn, impact glomerular filtration, including that governed by tubuloglomerular feedback. However, it is often difficult to discern the distinct effects of excess circulating insulin and impaired insulin actions, as exist in the insulin resistance individual, from the associated effects of obesity or elevated systolic blood pressure on the development and progression of kidney disease over time. Therefore, we review the experimental and clinical evidence for the distinct impact of insulin resistance on kidney function and disease.
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Affiliation(s)
- Adam Whaley-Connell
- Research Service, Harry S. Truman Memorial Veterans' Hospital, University of Missouri-Columbia School of Medicine, Columbia, Missouri, USA.,Diabetes and Cardiovascular Center, University of Missouri-Columbia School of Medicine, Columbia, Missouri, USA.,Division of Nephrology and Hypertension, University of Missouri-Columbia School of Medicine, Columbia, Missouri, USA.,Division of Endocrinology and Metabolism, University of Missouri-Columbia School of Medicine, Columbia, Missouri, USA.,Department of Medicine, University of Missouri-Columbia School of Medicine, Columbia, Missouri, USA
| | - James R Sowers
- Research Service, Harry S. Truman Memorial Veterans' Hospital, University of Missouri-Columbia School of Medicine, Columbia, Missouri, USA.,Diabetes and Cardiovascular Center, University of Missouri-Columbia School of Medicine, Columbia, Missouri, USA.,Division of Endocrinology and Metabolism, University of Missouri-Columbia School of Medicine, Columbia, Missouri, USA.,Department of Medicine, University of Missouri-Columbia School of Medicine, Columbia, Missouri, USA.,Department of Medical Pharmacology and Physiology, University of Missouri-Columbia School of Medicine, Columbia, Missouri, USA
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24
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González-Mariscal L, Miranda J, Raya-Sandino A, Domínguez-Calderón A, Cuellar-Perez F. ZO-2, a tight junction protein involved in gene expression, proliferation, apoptosis, and cell size regulation. Ann N Y Acad Sci 2017; 1397:35-53. [PMID: 28415133 DOI: 10.1111/nyas.13334] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2016] [Revised: 02/10/2017] [Accepted: 02/21/2017] [Indexed: 02/07/2023]
Abstract
ZO-2 is a peripheral tight junction protein that belongs to the membrane-associated guanylate kinase protein family. Here, we explain the modular and supramodular organization of ZO-2 that allows it to interact with a wide variety of molecules, including cell-cell adhesion proteins, cytoskeletal components, and nuclear factors. We also describe how ZO proteins evolved through metazoan evolution and analyze the intracellular traffic of ZO-2, as well as the roles played by ZO-2 at the plasma membrane and nucleus that translate into the regulation of proliferation, cell size, and apoptosis. In addition, we focus on the impact of ZO-2 expression on male fertility and on maladies like cancer, cholestasis, and hearing loss.
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Affiliation(s)
- Lorenza González-Mariscal
- Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies (Cinvestav), Mexico City, Mexico
| | - Jael Miranda
- Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies (Cinvestav), Mexico City, Mexico
| | - Arturo Raya-Sandino
- Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies (Cinvestav), Mexico City, Mexico
| | - Alaide Domínguez-Calderón
- Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies (Cinvestav), Mexico City, Mexico
| | - Francisco Cuellar-Perez
- Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies (Cinvestav), Mexico City, Mexico
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25
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Nistala R, Raja A, Pulakat L. mTORC1 inhibitors rapamycin and metformin affect cardiovascular markers differentially in ZDF rats. Can J Physiol Pharmacol 2017; 95:281-287. [PMID: 28177677 DOI: 10.1139/cjpp-2016-0567] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Mammalian target for rapamycin complex 1 (mTORC1) is a common target for the action of immunosuppressant macrolide rapamycin and glucose-lowering metformin. Inhibition of mTORC1 can exert both beneficial and detrimental effects in different pathologies. Here, we investigated the differential effects of rapamycin (1.2 mg/kg per day delivered subcutaneously for 6 weeks) and metformin (300 mg/kg per day delivered orally for 11 weeks) treatments on male Zucker diabetic fatty (ZDF) rats that mimic the cardiorenal pathology of type 2 diabetic patients and progress to insulin insufficiency. Rapamycin and metformin improved proteinuria, and rapamycin also reduced urinary gamma glutamyl transferase (GGT) indicating improvement of tubular health. Metformin reduced food and water intake, and urinary sodium and potassium, whereas rapamycin increased urinary sodium. Metformin reduced plasma alkaline phosphatase, but induced transaminitis as evidenced by significant increases in plasma AST and ALT. Metformin also induced hyperinsulinemia, but did not suppress fasting plasma glucose after ZDF rats reached 17 weeks of age, and worsened lipid profile. Rapamycin also induced mild transaminitis. Additionally, both rapamycin and metformin increased plasma uric acid and creatinine, biomarkers for cardiovascular and renal disease. These observations define how rapamycin and metformin differentially modulate metabolic profiles that regulate cardiorenal pathology in conditions of severe type 2 diabetes.
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Affiliation(s)
- Ravi Nistala
- a Division of Nephrology, Columbia School of Medicine, University of Missouri, Columbia, MO 65212, USA.,b Department of Medicine, Columbia School of Medicine, University of Missouri, Columbia, MO 65212, USA.,c Harry S. Truman Memorial Veterans Affairs Hospital, Columbia, MO 65201, USA
| | - Ahmad Raja
- b Department of Medicine, Columbia School of Medicine, University of Missouri, Columbia, MO 65212, USA.,c Harry S. Truman Memorial Veterans Affairs Hospital, Columbia, MO 65201, USA.,d Division of Cardiology, Columbia School of Medicine, University of Missouri, Columbia, MO 65212, USA
| | - Lakshmi Pulakat
- b Department of Medicine, Columbia School of Medicine, University of Missouri, Columbia, MO 65212, USA.,c Harry S. Truman Memorial Veterans Affairs Hospital, Columbia, MO 65201, USA.,d Division of Cardiology, Columbia School of Medicine, University of Missouri, Columbia, MO 65212, USA.,e Department of Nutrition and Exercise Physiology, University of Missouri, Columbia, MO 65211, USA
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26
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Bhattacharjee N, Barma S, Konwar N, Dewanjee S, Manna P. Mechanistic insight of diabetic nephropathy and its pharmacotherapeutic targets: An update. Eur J Pharmacol 2016; 791:8-24. [PMID: 27568833 DOI: 10.1016/j.ejphar.2016.08.022] [Citation(s) in RCA: 172] [Impact Index Per Article: 21.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 08/03/2016] [Accepted: 08/24/2016] [Indexed: 02/09/2023]
Abstract
Diabetic nephropathy (DN), a chronic complication of diabetes, is charecterized by glomerular hypertrophy, proteinuria, decreased glomerular filtration, and renal fibrosis resulting in the loss of renal function. Although the exact cause of DN remains unclear, several mechanisms have been postulated, such as hyperglycemia-induced renal hyper filtration and renal injury, AGEs-induced increased oxidative stress, activated PKC-induced increased production of cytokines, chemokines, and different inflammatory and apoptotic signals. Among various factors, oxidative stress has been suggested to play a major role underlying the onset and propagation of DN. It triggers several signaling pathways involved in DN, like AGEs, PKC cascade, JAK/STAT signaling, MAPK, mTOR, and SMAD. Oxidative stress-induced activation of both inflammatory and apoptotic signals are two major problems in the pathogenesis of DN. The FDA approved pharmacotherapeutic agents affecting against polyol pathway principally include anti-oxidants, like α-lipoic acid, vitamin E, and vitamin C. Kremezin and benfotiamine are the FDA approved AGEs inhibitors, another therapeutic target against DN. Ruboxistaurin, telmizartan, rapamycin, fenofibrate, aliskiren, and manidipine are some FDA approved pharmacotherapeutics effective against DN via diverse mechanisms. Beside this, some therapeutic agents are still waiting for FDA approval and few drugs without FDA approval are also prescribed in some countries for the management of DN. Despite the medications available in the market to treat DN, the involvement of multiple mechanisms makes it difficult to choose an optimum therapeutic agent. Therefore, much research is required to find out new therapeutic agent/strategies for an adequate pharmacotherapy of DN.
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Affiliation(s)
- Niloy Bhattacharjee
- Advanced Pharmacognosy Research Laboratory, Department of Pharmaceutical Technology, Jadavpur University, Raja S C Mullick Road, Kolkata 700032, India
| | - Sujata Barma
- Advanced Pharmacognosy Research Laboratory, Department of Pharmaceutical Technology, Jadavpur University, Raja S C Mullick Road, Kolkata 700032, India
| | - Nandita Konwar
- Biological Science and Technology Division, CSIR-NEIST, Jorhat, Assam 785006, India
| | - Saikat Dewanjee
- Advanced Pharmacognosy Research Laboratory, Department of Pharmaceutical Technology, Jadavpur University, Raja S C Mullick Road, Kolkata 700032, India.
| | - Prasenjit Manna
- Biological Science and Technology Division, CSIR-NEIST, Jorhat, Assam 785006, India.
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27
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Roles of mTOR complexes in the kidney: implications for renal disease and transplantation. Nat Rev Nephrol 2016; 12:587-609. [PMID: 27477490 DOI: 10.1038/nrneph.2016.108] [Citation(s) in RCA: 143] [Impact Index Per Article: 17.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
The mTOR pathway has a central role in the regulation of cell metabolism, growth and proliferation. Studies involving selective gene targeting of mTOR complexes (mTORC1 and mTORC2) in renal cell populations and/or pharmacologic mTOR inhibition have revealed important roles of mTOR in podocyte homeostasis and tubular transport. Important advances have also been made in understanding the role of mTOR in renal injury, polycystic kidney disease and glomerular diseases, including diabetic nephropathy. Novel insights into the roles of mTORC1 and mTORC2 in the regulation of immune cell homeostasis and function are helping to improve understanding of the complex effects of mTOR targeting on immune responses, including those that impact both de novo renal disease and renal allograft outcomes. Extensive experience in clinical renal transplantation has resulted in successful conversion of patients from calcineurin inhibitors to mTOR inhibitors at various times post-transplantation, with excellent long-term graft function. Widespread use of this practice has, however, been limited owing to mTOR-inhibitor- related toxicities. Unique attributes of mTOR inhibitors include reduced rates of squamous cell carcinoma and cytomegalovirus infection compared to other regimens. As understanding of the mechanisms by which mTORC1 and mTORC2 drive the pathogenesis of renal disease progresses, clinical studies of mTOR pathway targeting will enable testing of evolving hypotheses.
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28
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Domínguez-Calderón A, Ávila-Flores A, Ponce A, López-Bayghen E, Calderón-Salinas JV, Luis Reyes J, Chávez-Munguía B, Segovia J, Angulo C, Ramírez L, Gallego-Gutiérrez H, Alarcón L, Martín-Tapia D, Bautista-García P, González-Mariscal L. ZO-2 silencing induces renal hypertrophy through a cell cycle mechanism and the activation of YAP and the mTOR pathway. Mol Biol Cell 2016; 27:1581-95. [PMID: 27009203 PMCID: PMC4865316 DOI: 10.1091/mbc.e15-08-0598] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2015] [Accepted: 03/15/2016] [Indexed: 01/16/2023] Open
Abstract
Renal compensatory hypertrophy (RCH) restores normal kidney function after disease or loss of kidney tissue and is characterized by an increase in organ size due to cell enlargement and not to cell proliferation. In MDCK renal epithelial cells, silencing of the tight junction protein zona occludens 2 (ZO-2 KD) induces cell hypertrophy by two mechanisms: prolonging the time that cells spend at the G1 phase of the cell cycle due to an increase in cyclin D1 level, and augmenting the rate of protein synthesis. The latter is triggered by the nuclear accumulation and increased transcriptional activity of Yes-associated protein (YAP), the main target of the Hippo pathway, which results in decreased expression of phosphatase and tensin homologue. This in turn increased the level of phosphatidylinositol (3,4,5)-triphosphate, which transactivates the Akt/mammalian target of rapamycin pathway, leading to activation of the kinase S6K1 and increased synthesis of proteins and cell size. In agreement, in a rat model of uninephrectomy, RCH is accompanied by decreased expression of ZO-2 and nuclear expression of YAP. Our results reveal a novel role of ZO-2 as a modulator of cell size.
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Affiliation(s)
- Alaide Domínguez-Calderón
- Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies (CINVESTAV), México D.F. 07360, México
| | - Antonia Ávila-Flores
- Department of Immunology and Oncology, National Center of Biotechnology/CSIC, Darwin 3 UAM, E-28049 Madrid, Spain
| | - Arturo Ponce
- Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies (CINVESTAV), México D.F. 07360, México
| | - Esther López-Bayghen
- Department of Toxicology, Center for Research and Advanced Studies (CINVESTAV), México D.F. 07360, México
| | | | - José Luis Reyes
- Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies (CINVESTAV), México D.F. 07360, México
| | - Bibiana Chávez-Munguía
- Department of Infectomics and Molecular Pathogenesis, Center for Research and Advanced Studies (CINVESTAV), México D.F. 07360, México
| | - José Segovia
- Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies (CINVESTAV), México D.F. 07360, México
| | - Carla Angulo
- Department of Toxicology, Center for Research and Advanced Studies (CINVESTAV), México D.F. 07360, México
| | - Leticia Ramírez
- Department of Toxicology, Center for Research and Advanced Studies (CINVESTAV), México D.F. 07360, México
| | - Helios Gallego-Gutiérrez
- Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies (CINVESTAV), México D.F. 07360, México
| | - Lourdes Alarcón
- Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies (CINVESTAV), México D.F. 07360, México
| | - Dolores Martín-Tapia
- Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies (CINVESTAV), México D.F. 07360, México
| | - Pablo Bautista-García
- Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies (CINVESTAV), México D.F. 07360, México
| | - Lorenza González-Mariscal
- Department of Physiology, Biophysics and Neuroscience, Center for Research and Advanced Studies (CINVESTAV), México D.F. 07360, México
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29
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Wittenberg AD, Azar S, Klochendler A, Stolovich-Rain M, Avraham S, Birnbaum L, Binder Gallimidi A, Katz M, Dor Y, Meyuhas O. Phosphorylated Ribosomal Protein S6 Is Required for Akt-Driven Hyperplasia and Malignant Transformation, but Not for Hypertrophy, Aneuploidy and Hyperfunction of Pancreatic β-Cells. PLoS One 2016; 11:e0149995. [PMID: 26919188 PMCID: PMC4769037 DOI: 10.1371/journal.pone.0149995] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/08/2015] [Accepted: 02/08/2016] [Indexed: 12/31/2022] Open
Abstract
Constitutive expression of active Akt (Akttg) drives hyperplasia and hypertrophy of pancreatic β-cells, concomitantly with increased insulin secretion and improved glucose tolerance, and at a later stage the development of insulinoma. To determine which functions of Akt are mediated by ribosomal protein S6 (rpS6), an Akt effector, we generated mice that express constitutive Akt in β-cells in the background of unphosphorylatable ribosomal protein S6 (rpS6P-/-). rpS6 phosphorylation deficiency failed to block Akttg-induced hypertrophy and aneuploidy in β-cells, as well as the improved glucose homeostasis, indicating that Akt carries out these functions independently of rpS6 phosphorylation. In contrast, rpS6 phosphorylation deficiency efficiently restrained the reduction in nuclear localization of the cell cycle inhibitor p27, as well as the development of Akttg-driven hyperplasia and tumor formation in β-cells. In vitro experiments with Akttg and rpS6P-/-;Akttg fibroblasts demonstrated that rpS6 phosphorylation deficiency leads to reduced translation fidelity, which might underlie its anti-tumorigenic effect in the pancreas. However, the role of translation infidelity in tumor suppression cannot simply be inferred from this heterologous experimental model, as rpS6 phosphorylation deficiency unexpectedly elevated the resistance of Akttg fibroblasts to proteotoxic, genotoxic as well as autophagic stresses. In contrast, rpS6P-/- fibroblasts exhibited a higher sensitivity to these stresses upon constitutive expression of oncogenic Kras. The latter result provides a possible mechanistic explanation for the ability of rpS6 phosphorylation deficiency to enhance DNA damage and protect mice from Kras-induced neoplastic transformation in the exocrine pancreas. We propose that Akt1 and Kras exert their oncogenic properties through distinct mechanisms, even though both show addiction to rpS6 phosphorylation.
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Affiliation(s)
- Avigail Dreazen Wittenberg
- Department of Biochemistry and Molecular Biology, The Institute for Medical Research-Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Shahar Azar
- Department of Biochemistry and Molecular Biology, The Institute for Medical Research-Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Agnes Klochendler
- Department of Developmental Biology and Cancer Research, The Institute for Medical Research-Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Miri Stolovich-Rain
- Department of Developmental Biology and Cancer Research, The Institute for Medical Research-Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Shlomit Avraham
- Department of Biochemistry and Molecular Biology, The Institute for Medical Research-Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Lea Birnbaum
- Department of Biochemistry and Molecular Biology, The Institute for Medical Research-Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Adi Binder Gallimidi
- Department of Biochemistry and Molecular Biology, The Institute for Medical Research-Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Maximiliano Katz
- Department of Biochemistry and Molecular Biology, The Institute for Medical Research-Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Yuval Dor
- Department of Developmental Biology and Cancer Research, The Institute for Medical Research-Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
| | - Oded Meyuhas
- Department of Biochemistry and Molecular Biology, The Institute for Medical Research-Israel-Canada, The Hebrew University-Hadassah Medical School, Jerusalem, Israel
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30
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Zhang X, Gibson ME, Li ZL, Zhu XY, Jordan KL, Lerman A, Lerman LO. Autophagy Portends the Level of Cardiac Hypertrophy in Experimental Hypertensive Swine Model. Am J Hypertens 2016; 29:81-9. [PMID: 25904651 DOI: 10.1093/ajh/hpv057] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2014] [Accepted: 03/27/2015] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Left ventricular (LV) hypertrophy (LVH) plays an important role in hypertensive heart disease, and may be accompanied by myocardial autophagy. However, the pattern of autophagy during evolution of LVH is unclear. We hypothesized that autophagy activation indicates advancing cardiac LVH with tissue remodeling. METHODS Ten domestic pigs with a 10-week unilateral renovascular hypertension (HTN) were classified as mild or moderate HTN (n = 5 each group) based on the degree of renal artery stenosis (above or below 75%). Seven normal pigs served as controls. Left ventricular remodeling, function, and microvascular density were assessed using multi-detector- and micro-computed tomography and histology. Markers of myocardial autophagic and endoplasmic reticulum (ER) stress-related unfolded protein response (UPR), apoptosis, and fibrosis were examined ex vivo. RESULTS Both HTN groups had increased myocyte cross-sectional area, but it was greater in moderate HTN, accompanied by elevated LV muscle-mass. Moderate, but not mild HTN, also showed impaired microvascular density and impaired myocardial perfusion. Autophagy mediators were unaltered in mild HTN but UPR markers were increased, while in moderate HTN they were all upregulated, whereas UPR markers were suppressed. Myocardial apoptosis and fibrosis were also greater in moderate HTN. Autophagic proteins were correlated with LVH and fibrosis. CONCLUSIONS Autophagic activity is stimulated during the exacerbation of LVH, following a transient early increase in ER stress, and may be involved in the progression of cardiac remodeling in renovascular hypertensive heart disease.
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Affiliation(s)
- Xin Zhang
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Matthew E Gibson
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Zi-Lun Li
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA; Division of Vascular Surgery, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou, China
| | - Xiang-Yang Zhu
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Kyra L Jordan
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Amir Lerman
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA
| | - Lilach O Lerman
- Division of Nephrology and Hypertension, Mayo Clinic, Rochester, Minnesota, USA; Division of Cardiovascular Diseases, Mayo Clinic, Rochester, Minnesota, USA.
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31
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Wu H, Chen J, Xu J, Dong Z, Meyuhas O, Chen JK. Blocking rpS6 Phosphorylation Exacerbates Tsc1 Deletion-Induced Kidney Growth. J Am Soc Nephrol 2015; 27:1145-58. [PMID: 26296742 DOI: 10.1681/asn.2014121264] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2014] [Accepted: 07/16/2015] [Indexed: 11/03/2022] Open
Abstract
The molecular mechanisms underlying renal growth and renal growth-induced nephron damage remain poorly understood. Here, we report that in murine models, deletion of the tuberous sclerosis complex protein 1 (Tsc1) in renal proximal tubules induced strikingly enlarged kidneys, with minimal cystogenesis and occasional microscopic tumorigenesis. Signaling studies revealed hyperphosphorylation of eukaryotic translation initiation factor 4E-binding protein 1 (4E-BP1) and increased phosphorylation of ribosomal protein S6 (rpS6) in activated renal tubules. Notably, knockin of a nonphosphorylatable rpS6 in these Tsc1-mutant mice exacerbated cystogenesis and caused drastic nephron damage and renal fibrosis, leading to kidney failure and a premature death rate of 67% by 9 weeks of age. In contrast, Tsc1 single-mutant mice were all alive and had far fewer renal cysts at this age. Mechanistic studies revealed persistent activation of mammalian target of rapamycin complex 1 (mTORC1) signaling causing hyperphosphorylation and consequent accumulation of 4E-BP1, along with greater cell proliferation, in the renal tubules of Tsc1 and rpS6 double-mutant mice. Furthermore, pharmacologic treatment of Tsc1 single-mutant mice with rapamycin reduced hyperphosphorylation and accumulation of 4E-BP1 but also inhibited phosphorylation of rpS6. Rapamycin also exacerbated cystic and fibrotic lesions and impaired kidney function in these mice, consequently leading to a premature death rate of 40% within 2 weeks of treatment, despite destroying tumors and decreasing kidney size. These findings indicate that Tsc1 prevents aberrant renal growth and tumorigenesis by inhibiting mTORC1 signaling, whereas phosphorylated rpS6 suppresses cystogenesis and fibrosis in Tsc1-deleted kidneys.
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Affiliation(s)
- Huijuan Wu
- Department of Cellular Biology and Anatomy, Department of Medicine, Medical College of Georgia, Georgia Regents University, Augusta, Georgia
| | - Jianchun Chen
- Division of Nephrology and Hypertension, Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee
| | - Jinxian Xu
- Department of Cellular Biology and Anatomy, Department of Medicine, Medical College of Georgia, Georgia Regents University, Augusta, Georgia
| | - Zheng Dong
- Department of Cellular Biology and Anatomy, Research Department, Charlie Norwood VA Medical Center, Augusta, Georgia; and
| | - Oded Meyuhas
- Department of Biochemistry and Molecular Biology, Institute for Medical Research Israel-Canada, Hebrew University Hadassah Medical School, Jerusalem, Israel
| | - Jian-Kang Chen
- Department of Cellular Biology and Anatomy, Department of Medicine, Medical College of Georgia, Georgia Regents University, Augusta, Georgia;
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32
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Ribosomal Protein S6 Phosphorylation: Four Decades of Research. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 320:41-73. [PMID: 26614871 DOI: 10.1016/bs.ircmb.2015.07.006] [Citation(s) in RCA: 182] [Impact Index Per Article: 20.2] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The phosphorylation of ribosomal protein S6 (rpS6) has been described for the first time about four decades ago. Since then, numerous studies have shown that this modification occurs in response to a wide variety of stimuli on five evolutionarily conserved serine residues. However, despite a large body of information on the respective kinases and the signal transduction pathways, the physiological role of rpS6 phosphorylation remained obscure until genetic manipulations were applied in both yeast and mammals in an attempt to block this modification. Thus, studies based on both mice and cultured cells subjected to disruption of the genes encoding rpS6 and the respective kinases, as well as the substitution of the phosphorylatable serine residues in rpS6, have laid the ground for the elucidation of the multiple roles of this protein and its posttranslational modification. This review focuses primarily on newly identified kinases that phosphorylate rpS6, pathways that transduce various signals into rpS6 phosphorylation, and the recently established physiological functions of this modification. It should be noted, however, that despite the significant progress made in the last decade, the molecular mechanism(s) underlying the diverse effects of rpS6 phosphorylation on cellular and organismal physiology are still poorly understood.
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Chen JK, Nagai K, Chen J, Plieth D, Hino M, Xu J, Sha F, Ikizler TA, Quarles CC, Threadgill DW, Neilson EG, Harris RC. Phosphatidylinositol 3-kinase signaling determines kidney size. J Clin Invest 2015; 125:2429-44. [PMID: 25985273 DOI: 10.1172/jci78945] [Citation(s) in RCA: 51] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Accepted: 03/17/2015] [Indexed: 01/20/2023] Open
Abstract
Kidney size adaptively increases as mammals grow and in response to the loss of 1 kidney. It is not clear how kidneys size themselves or if the processes that adapt kidney mass to lean body mass also mediate renal hypertrophy following unilateral nephrectomy (UNX). Here, we demonstrated that mice harboring a proximal tubule-specific deletion of Pten (Pten(ptKO)) have greatly enlarged kidneys as the result of persistent activation of the class I PI3K/mTORC2/AKT pathway and an increase of the antiproliferative signals p21(Cip1/WAF) and p27(Kip1). Administration of rapamycin to Pten(ptKO) mice diminished hypertrophy. Proximal tubule-specific deletion of Egfr in Pten(ptKO) mice also attenuated class I PI3K/mTORC2/AKT signaling and reduced the size of enlarged kidneys. In Pten(ptKO) mice, UNX further increased mTORC1 activation and hypertrophy in the remaining kidney; however, mTORC2-dependent AKT phosphorylation did not increase further in the remaining kidney of Pten(ptKO) mice, nor was it induced in the remaining kidney of WT mice. After UNX, renal blood flow and amino acid delivery to the remaining kidney rose abruptly, followed by increased amino acid content and activation of a class III PI3K/mTORC1/S6K1 pathway. Thus, our findings demonstrate context-dependent roles for EGFR-modulated class I PI3K/mTORC2/AKT signaling in the normal adaptation of kidney size and PTEN-independent, nutrient-dependent class III PI3K/mTORC1/S6K1 signaling in the compensatory enlargement of the remaining kidney following UNX.
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Barlow AD, Thomas DC. Autophagy in Diabetes: β-Cell Dysfunction, Insulin Resistance, and Complications. DNA Cell Biol 2015; 34:252-60. [DOI: 10.1089/dna.2014.2755] [Citation(s) in RCA: 79] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Affiliation(s)
- Adam D. Barlow
- Department of Surgery, University of Cambridge, Cambridge, United Kingdom
- NIHR Cambridge Biomedical Research Campus, Cambridge, United Kingdom
| | - David C. Thomas
- NIHR Cambridge Biomedical Research Campus, Cambridge, United Kingdom
- Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
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Deng M, Luo Y, Li Y, Yang Q, Deng X, Wu P, Ma H. Klotho gene delivery ameliorates renal hypertrophy and fibrosis in streptozotocin-induced diabetic rats by suppressing the Rho-associated coiled-coil kinase signaling pathway. Mol Med Rep 2015; 12:45-54. [PMID: 25695625 PMCID: PMC4438939 DOI: 10.3892/mmr.2015.3367] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/27/2014] [Accepted: 11/12/2014] [Indexed: 01/08/2023] Open
Abstract
The present study aimed to investigate whether klotho gene delivery attenuated renal hypertrophy and fibrosis in streptozotocin-induced diabetic rats. A recombinant adeno-associated virus (rAAV) carrying mouse klotho full-length cDNA (rAAV.mKL), was constructed for in vivo investigation of klotho expression. Diabetes was induced in rats by a single tail vein injection of 60 mg/kg streptozotocin. Subsequently, the diabetic rats received an intravenous injection of rAAV.mKL, rAAV.green fluorescent protein (GFP) or phosphate-buffered saline (PBS). The Sprague-Dawley rat group received PBS and served as the control group. After 12 weeks, all the rats were sacrificed and ELISA, immunohistochemical and histological analyses, fluorescence microscopy, semi-quantitative reverse transcription-polymerase chain reaction and western blottin were performed. A single dose of rAAV.mKL was found to prevent the progression of renal hypertrophy and fibrosis for at least 12 weeks (duration of study). Klotho expression was suppressed in the diabetic rats, but was increased by rAAV.mKL delivery. rAAV.mKL significantly suppressed diabetes-induced renal hypertrophy and histopathological changes, reduced renal collagen fiber generation and decreased kidney hypertrophy index. In addition, rAAV.mKL decreased the protein expression levels of fibronectin and vimentin, while it downregulated the mRNA expression and activity of Rho-associated coiled-coil kinase (ROCK)I in the kidneys of the diabetic rats. These results indicated that klotho gene delivery ameliorated renal hypertrophy and fibrosis in diabetic rats, possibly by suppressing the ROCK signaling pathway. This may offer a novel approach for the long-term control and renoprotection of diabetes.
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Affiliation(s)
- Minghong Deng
- Department of Geriatrics, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
| | - Yumei Luo
- Department of Geriatrics, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
| | - Yunkui Li
- Department of Geriatrics, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
| | - Qiuchen Yang
- Department of Geriatrics, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
| | - Xiaoqin Deng
- Department of Geriatrics, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
| | - Ping Wu
- Department of Geriatrics, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
| | - Houxun Ma
- Department of Geriatrics, The First Affiliated Hospital of Chongqing Medical University, Chongqing 400016, P.R. China
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Phosphorylation of ribosomal protein S6 mediates compensatory renal hypertrophy. Kidney Int 2014; 87:543-56. [PMID: 25229342 PMCID: PMC4344886 DOI: 10.1038/ki.2014.302] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2014] [Revised: 07/11/2014] [Accepted: 07/24/2014] [Indexed: 01/15/2023]
Abstract
The molecular mechanism underlying renal hypertrophy and progressive nephron damage remains poorly understood. Here we generated congenic ribosomal protein S6 (rpS6) knockin mice expressing non-phosphorylatable rpS6 and found that uninephrectomy-induced renal hypertrophy was significantly blunted in these knockin mice. Uninephrectomy-induced increases in cyclin D1 and decreases in cyclin E in the remaining kidney were attenuated in the knockin mice compared to their wild-type littermates. Uninephrectomy induced rpS6 phosphorylation in the wild type mice; however, no rpS6 phosphorylation was detected in uninephrectomized or sham-operated knockin mice. Nonetheless, uninephrectomy stimulated comparable 4E-BP1 phosphorylation in both knockin and wild type mice, indicating that mTORC1 was still activated in the knockin mice. Moreover, the mTORC1 inhibitor rapamycin prevented both rpS6 and 4E-BP1 phosphorylation, significantly blunted uninephrectomy-induced renal hypertrophy in wild type mice, but did not prevent residual renal hypertrophy despite inhibiting 4E-BP1 phosphorylation in uninephrectomized knockin mice. Thus, both genetic and pharmacological approaches unequivocally demonstrate that phosphorylated rpS6 is a downstream effector of the mTORC1-S6K1 signaling pathway mediating renal hypertrophy. Hence, rpS6 phosphorylation facilitates the increase in cyclin D1 and decrease in cyclin E1 that underlie the hypertrophic nature of uninephrectomy-induced kidney growth.
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Bahrami-B F, Ataie-Kachoie P, Pourgholami MH, Morris DL. p70 Ribosomal protein S6 kinase (Rps6kb1): an update. J Clin Pathol 2014; 67:1019-25. [PMID: 25100792 DOI: 10.1136/jclinpath-2014-202560] [Citation(s) in RCA: 49] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
The Rps6kb1 gene encodes the 70 kDa ribosomal protein S6 kinase (p70S6K), which is a serine/threonine kinase regulated by phosphoinositide 3-kinase (PI3K)/mammalian target of rapamycin (mTOR) pathway. p70S6K plays a crucial role in controlling cell cycle, growth and survival. The PI3K/mTOR signalling pathway is one of the major mechanisms for controlling cell survival, proliferation and metabolism and is the central regulator of translation of some components of protein synthesis system. Upon activation, this kinase phosphorylates S6 protein of ribosomal subunit 40S resulting in selective translation of unique family of mRNAs that contain oligopyrimidine tract on 5' transcriptional site (5'TOP). 5'TOP mRNAs are coding the components of translational apparatus including ribosomal proteins and elongation factors. Due to the role of p70S6K in protein synthesis and also its involvement in a variety of human diseases ranging from diabetes and obesity to cancer, p70S6K is now being considered as a new therapeutic target for drug development. Furthermore, p70S6K acts as a biomarker for response to immunosuppressant as well as anticancer effects of inhibitors of the mTOR. Because of the narrow therapeutic index of mTOR inhibitors, drug monitoring is essential, and this is usually done by measuring blood drug levels, therapeutic response and drug-induced adverse effects. Recent studies have suggested that plasma p70S6K is a reliable index for the monitoring of patient response to mTOR inhibitors. Therefore, a better understanding of p70S6K and its role in various pathological conditions could enable the development of strategies to aid diagnosis, prognosis and treatment schedules.
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Affiliation(s)
- Farnaz Bahrami-B
- Cancer research laboratories, Department of Surgery, St George and Sutherland Clinical School, University of New South Wales, Sydney, Australia
| | | | | | - David L Morris
- Cancer research laboratories, Department of Surgery, St George and Sutherland Clinical School, University of New South Wales, Sydney, Australia
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Role of nutrient-sensing signals in the pathogenesis of diabetic nephropathy. BIOMED RESEARCH INTERNATIONAL 2014; 2014:315494. [PMID: 25126552 PMCID: PMC4122096 DOI: 10.1155/2014/315494] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/25/2014] [Accepted: 05/13/2014] [Indexed: 02/06/2023]
Abstract
Diabetic nephropathy is the leading cause of end-stage renal disease worldwide. The multipronged drug approach still fails to fully prevent the onset and progression of diabetic nephropathy. Therefore, a new therapeutic target to improve the prognosis of diabetic nephropathy is urgently required. Nutrient-sensing signals and their related intracellular machinery have evolved to combat prolonged periods of starvation in mammals; and these systems are conserved in the kidney. Recent studies have suggested that the activity of three nutrient-sensing signals, mTORC1, AMPK, and Sirt1, is altered in the diabetic kidney. Furthermore, autophagy activity, which is regulated by the above-mentioned nutrient-sensing signals, is also altered in both podocytes and proximal tubular cells under diabetic conditions. Under diabetic conditions, an altered nutritional state owing to nutrient excess may disturb cellular homeostasis regulated by nutrient-responsible systems, leading to exacerbation of organelle dysfunction and diabetic nephropathy. In this review, we discuss new findings showing relationships between nutrient-sensing signals, autophagy, and diabetic nephropathy and suggest the therapeutic potential of nutrient-sensing signals in diabetic nephropathy.
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The bigger the better: determining nephron size in kidney. Pediatr Nephrol 2014; 29:525-30. [PMID: 23974984 PMCID: PMC3944135 DOI: 10.1007/s00467-013-2581-x] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/04/2013] [Revised: 07/12/2013] [Accepted: 07/15/2013] [Indexed: 10/26/2022]
Abstract
The main functions of the kidney are to excrete metabolic waste products and actively reabsorb essential molecules such as amino acids, ions, glucose and water. In humans, a wide range of genetic disorders exist characterized by wasting of metabolically important compounds. At the cellular level, more than 20 highly specialized renal epithelial cell types located in different segments of the nephron contribute to the reabsorption process. In particular, proximal tubular cells play a crucial role and are uniquely adapted to maximize reabsorption efficiency. They accommodate high numbers of transporters and channels by increasing the apical surface area in contact with the primary filtrate by forming a brush border as well as undergoing hypertrophy and hyperplasia. This adaptation is evolutionarily conserved and is detected in the primitive pronephric kidney of fish and amphibians as well as the metanephric kidney of higher vertebrates. Surprisingly, signaling pathways regulating these three processes have remained largely unknown. Here we summarize recent studies that highlight the early phases of kidney development as a critical juncture in establishing proximal tubule size.
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Nistala R, Whaley-Connell A. Resistance to insulin and kidney disease in the cardiorenal metabolic syndrome; role for angiotensin II. Mol Cell Endocrinol 2013; 378:53-8. [PMID: 23416840 PMCID: PMC3711952 DOI: 10.1016/j.mce.2013.02.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/08/2012] [Revised: 01/03/2013] [Accepted: 02/06/2013] [Indexed: 12/14/2022]
Abstract
The presence of insulin resistance is increasingly recognized as an important contributor to early stage kidney disease independent of the contribution of diabetes. Important in this relationship is the strong correlation between hyperinsulinemia and low levels of albuminuria (e.g. microalbuminuria). Recent work highlight mechanisms for glomerular/tubulointerstitial injury with excess insulin and emerging evidence identifies a unique role for insulin metabolic signaling and altered handling of salt reabsorption at the level of the proximal tubule. Evidence is also emerging for the role of insulin signaling in the glomerulus both epithelial and endothelial. Central to the mechanism of injury is inappropriate activation of the RAAS.
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Affiliation(s)
- Ravi Nistala
- University of Missouri School of Medicine, Diabetes and Cardiovascular Center, Departments of Internal Medicine, Divisions of Nephrology and Hypertension, United States; Dialysis Clinics Inc., Lemone Industrial Blvd., Columbia MO, United States.
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Ohkawa S, Yanagida M, Uchikawa T, Yoshida T, Ikegaya N, Kumagai H. Attenuation of the activated mammalian target of rapamycin pathway might be associated with renal function reserve by a low-protein diet in the rat remnant kidney model. Nutr Res 2013; 33:761-71. [DOI: 10.1016/j.nutres.2013.06.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/05/2012] [Revised: 06/10/2013] [Accepted: 06/21/2013] [Indexed: 10/26/2022]
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Chen J, Chen JK, Conway EM, Harris RC. Survivin mediates renal proximal tubule recovery from AKI. J Am Soc Nephrol 2013; 24:2023-33. [PMID: 23949800 DOI: 10.1681/asn.2013010076] [Citation(s) in RCA: 75] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
AKI induces the renoprotective upregulation of survivin expression in kidney epithelial cells, but the underlying mechanisms have not been identified. To determine the role of survivin in renal recovery from AKI, we generated mice with renal proximal tubule-specific deletion of survivin (survivin(ptKO)). Renal survivin expression increased substantially in response to ischemia-reperfusion (I/R) injury in control littermates but remained minimal in survivin(ptKO) mice. Functional and histologic data indicated similar degrees of renal injury in survivin(ptKO) and control mice 24 hours after reperfusion, but recovery was markedly delayed in survivin(ptKO) mice. In MCT cells, a mouse renal proximal tubule cell line, ATP depletion by antimycin A treatment upregulated survivin expression through a phospho-STAT3-dependent pathway. In wild-type mice, inhibition of STAT3 kinase diminished I/R-induced upregulation of STAT3 phosphorylation and survivin expression and delayed recovery. Furthermore, I/R injury activated Notch-2 signaling, and a γ-secretase inhibitor suppressed I/R-induced Notch-2 signaling, STAT3 phosphorylation, and survivin expression and delayed recovery. In MCT cells, inhibition of γ-secretase similarly attenuated antimycin A-induced Notch-2 activation, upregulation of survivin, and phosphorylation of STAT3, but STAT3 kinase inhibition did not prevent Notch-2 activation. Therefore, these data suggest that STAT3 phosphorylation and subsequent upregulation of survivin expression mediated by Notch-2 signaling in renal proximal tubule epithelial cells aid in the functional and structural recovery of the kidney from AKI.
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Affiliation(s)
- Jianchun Chen
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee
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Chen J, Chen MX, Fogo AB, Harris RC, Chen JK. mVps34 deletion in podocytes causes glomerulosclerosis by disrupting intracellular vesicle trafficking. J Am Soc Nephrol 2013; 24:198-207. [PMID: 23291473 PMCID: PMC3559479 DOI: 10.1681/asn.2012010101] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2012] [Accepted: 11/06/2012] [Indexed: 01/07/2023] Open
Abstract
Recent studies have suggested that autophagy is a key mechanism in maintaining the integrity of podocytes. The mammalian homologue of yeast vacuolar protein sorting defective 34 (mVps34) has been implicated in the regulation of autophagy, but its role in podocytes is unknown. We generated a line of podocyte-specific mVps34-knockout (mVps34(pdKO)) mice, which were born at Mendelian ratios. These mice appeared grossly normal at 2 weeks of age but exhibited growth retardation and were significantly smaller than control mice by 6 weeks of age, with no difference in ratios of kidney to body weight. mVps34(pdKO) mice developed significant proteinuria by 3 weeks of age, developed severe kidney lesions by 5-6 weeks of age, and died before 9 weeks of age. There was striking podocyte vacuolization and proteinaceous casts, with marked glomerulosclerosis and interstitial fibrosis by 6 weeks of age. Electron microscopy revealed numerous enlarged vacuoles and increased autophagosomes in the podocytes, with complete foot process effacement and irregular and thickened glomerular basement membranes. Immunoblotting of isolated glomerular lysates revealed markedly elevated markers specific for lysosomes (LAMP1 and LAMP2) and autophagosomes (LC3-II/I). Immunofluorescence staining confirmed that the enlarged vacuoles originated from lysosomes. In conclusion, these results demonstrate an indispensable role for mVps34 in the trafficking of intracellular vesicles to protect the normal cellular metabolism, structure, and function of podocytes.
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Affiliation(s)
- Jianchun Chen
- Department of Medicine, Department of Pathology, and Department of Microbiology & Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee, and
| | - Mystie X. Chen
- Department of Medicine, Department of Pathology, and Department of Microbiology & Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee, and
| | - Agnes B. Fogo
- Department of Medicine, Department of Pathology, and Department of Microbiology & Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee, and
| | - Raymond C. Harris
- Department of Medicine, Department of Pathology, and Department of Microbiology & Immunology, Vanderbilt University School of Medicine, Nashville, Tennessee, and
| | - Jian-Kang Chen
- Section of Experimental Medicine, Department of Medicine, Georgia Regents University, Augusta, Georgia
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Brilli LL, Swanhart LM, de Caestecker MP, Hukriede NA. HDAC inhibitors in kidney development and disease. Pediatr Nephrol 2013; 28:1909-21. [PMID: 23052657 PMCID: PMC3751322 DOI: 10.1007/s00467-012-2320-8] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/27/2012] [Revised: 09/11/2012] [Accepted: 09/12/2012] [Indexed: 12/13/2022]
Abstract
The discovery that histone deacetylase inhibitors (HDACis) can attenuate acute kidney injury (AKI)-mediated damage and reduce fibrosis in kidney disease models has opened the possibility of utilizing HDACis as therapeutics for renal injury. Studies to date have made it abundantly clear that HDACi treatment results in a plethora of molecular changes, which are not always linked to histone acetylation, and that there is an essential need to understand the specific target(s) of any HDACi of interest. New lines of investigation are beginning to delve more deeply into target identification of specific HDACis and to address the relative toxicity of different HDACi classes. This review will focus on the utilization of HDACis during kidney organogenesis, injury, and disease, as well as on the development of these compounds as therapeutics.
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Affiliation(s)
- Lauren L. Brilli
- Department of Developmental Biology, University of Pittsburgh, 3501 5th Ave., 5061 BST3, Pittsburgh, PA 15213 USA
| | - Lisa M. Swanhart
- Department of Developmental Biology, University of Pittsburgh, 3501 5th Ave., 5061 BST3, Pittsburgh, PA 15213 USA
| | - Mark P. de Caestecker
- Department of Medicine, Division of Nephrology, Vanderbilt University Medical Center, Nashville, TN USA
| | - Neil A. Hukriede
- Department of Developmental Biology, University of Pittsburgh, 3501 5th Ave., 5061 BST3, Pittsburgh, PA 15213 USA
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Marshall WF, Young KD, Swaffer M, Wood E, Nurse P, Kimura A, Frankel J, Wallingford J, Walbot V, Qu X, Roeder AHK. What determines cell size? BMC Biol 2012; 10:101. [PMID: 23241366 PMCID: PMC3522064 DOI: 10.1186/1741-7007-10-101] [Citation(s) in RCA: 148] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2012] [Accepted: 12/12/2012] [Indexed: 11/16/2022] Open
Affiliation(s)
- Wallace F Marshall
- Department of Biochemistry and Biophysics, Center for Systems and Synthetic Biology, University of California, San Francisco, 600 16th St, San Francisco, CA 94158, USA
| | - Kevin D Young
- Department of Microbiology and Immunology, University of Arkansas for Medical Sciences, Little Rock, AR 72205, USA
| | - Matthew Swaffer
- Cell Cycle Lab, Cancer Research UK, London Research Institute, 44 Lincoln's Inn Fields, London, WC2A 3LY, UK
| | - Elizabeth Wood
- Cell Cycle Lab, Cancer Research UK, London Research Institute, 44 Lincoln's Inn Fields, London, WC2A 3LY, UK
| | - Paul Nurse
- Cell Cycle Lab, Cancer Research UK, London Research Institute, 44 Lincoln's Inn Fields, London, WC2A 3LY, UK
- Laboratory of Yeast Genetics and Biology, The Rockeller University, 1230 York Avenue, New York, NY 10065, USA
- The Francis Crick Institute, Euston Road 215, London, NW1 2BE, UK
| | - Akatsuki Kimura
- Cell Architecture Laboratory, Structural Biology Center, National Institute of Genetics, Yata 1111, Mishima, Shizuoka 411-8540, Japan
| | - Joseph Frankel
- Department of Biology, University of Iowa, 129 E. Jefferson Street, Iowa City, IA 52242, USA
| | - John Wallingford
- HHMI & Molecular Cell and Developmental Biology, University of Texas, Austin, 78712, USA
| | - Virginia Walbot
- Virginia WalbotDepartment of Biology, Stanford University, Stanford, CA 72205, USA
| | - Xian Qu
- Xian Qu, Cornell University, 244 Weill Hall, 526 Campus Rd, Ithaca, NY 14853, USA
| | - Adrienne HK Roeder
- Cornell University, 239 Weill Hall, 526 Campus Rd, Ithaca, NY 14853, USA
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Chen J, Chen JK, Harris RC. Deletion of the epidermal growth factor receptor in renal proximal tubule epithelial cells delays recovery from acute kidney injury. Kidney Int 2012; 82:45-52. [PMID: 22418982 PMCID: PMC3376190 DOI: 10.1038/ki.2012.43] [Citation(s) in RCA: 101] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2011] [Revised: 11/27/2011] [Accepted: 12/20/2011] [Indexed: 12/13/2022]
Abstract
To determine the role of epidermal growth factor receptor (EGFR) activation in renal functional and structural recovery from acute kidney injury (AKI), we generated mice with a specific EGFR deletion in the renal proximal tubule (EGFR(ptKO)). Ischemia-reperfusion injury markedly activated EGFR in control littermate mice; however, this was inhibited in either the knockout or wild-type mice given erlotinib, a specific EGFR tyrosine kinase inhibitor. Blood urea nitrogen and serum creatinine increased to a comparable level in EGFR(ptKO) and control mice 24 h after reperfusion, but the subsequent rate of renal function recovery was markedly slowed in the knockout mice. Twenty-four hours after reperfusion, both the knockout and the inhibitor-treated mice had a similar degree of histologic renal injury as control mice, but at day 6 there was minimal evidence of injury in the control mice while both EGFR(ptKO) and erlotinib-treated mice still had persistent proximal tubule dilation, epithelial simplification, and cast formation. Additionally, renal cell proliferation was delayed due to decreased ERK and Akt signaling. Thus, our studies provide both genetic and pharmacologic evidence that proximal tubule EGFR activation plays an important role in the recovery phase after acute kidney injury.
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Affiliation(s)
- Jianchun Chen
- Department of Medicine, Vanderbilt University School of Medicine, Nashville, Tennessee 37232, USA.
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47
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Jang HS, Kim JI, Kim J, Na YK, Park JW, Park KM. Bone marrow derived cells and reactive oxygen species in hypertrophy of contralateral kidney of transient unilateral renal ischemia-induced mouse. Free Radic Res 2012; 46:903-11. [DOI: 10.3109/10715762.2012.686664] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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Lieberthal W, Levine JS. Mammalian target of rapamycin and the kidney. II. Pathophysiology and therapeutic implications. Am J Physiol Renal Physiol 2012; 303:F180-91. [PMID: 22496407 DOI: 10.1152/ajprenal.00015.2012] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The mTOR pathway plays an important role in a number of common renal diseases, including acute kidney injury (AKI), diabetic nephropathy (DN), and polycystic kidney diseases (PKD). The activity of mTOR complex 1 (mTORC1) is necessary for renal regeneration and repair after AKI, and inhibition of mTORC1 by rapamycin has been shown to delay recovery from ischemic AKI in animal studies, and to prolong delayed graft function in humans who have received a kidney transplant. For this reason, administration of rapamycin should be delayed or discontinued in patients with AKI until full recovery of renal function has occurred. On the other hand, inappropriately high mTORC1 activity contributes to the progression of the metabolic syndrome, the development of type 2 diabetes, and the pathogenesis of DN. In addition, chronic hyperactivity of mTORC1, and possibly also mTORC2, contributes to cyst formation and enlargement in a number of forms of PKD. Inhibition of mTOR, using either rapamycin (which inhibits predominantly mTORC1) or "catalytic" inhibitors (which effectively inhibit both mTORC1 and mTORC2), provide exciting possibilities for novel forms of treatment of DN and PKD. In this second part of the review, we will examine the role of mTOR in the pathophysiology of DN and PKD, as well as the potential utility of currently available and newly developed inhibitors of mTOR to slow the progression of DN and/or PKD.
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Affiliation(s)
- Wilfred Lieberthal
- Stony Brook Univ. Medical Center, Health Sciences Center, Stony Brook, NY 11794-8166, USA.
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Rapamycin ameliorates kidney fibrosis by inhibiting the activation of mTOR signaling in interstitial macrophages and myofibroblasts. PLoS One 2012; 7:e33626. [PMID: 22470459 PMCID: PMC3314672 DOI: 10.1371/journal.pone.0033626] [Citation(s) in RCA: 90] [Impact Index Per Article: 7.5] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/04/2011] [Accepted: 02/14/2012] [Indexed: 01/11/2023] Open
Abstract
Interstitial fibrosis is an inevitable outcome of all kinds of progressive chronic kidney disease (CKD). Emerging data indicate that rapamycin can ameliorate kidney fibrosis by reducing the interstitial infiltrates and accumulation of extra cellular matrix (ECM). However, the cellular mechanism that regulates those changes has not been well understood yet. In this study, we revealed the persistent activation of mammalian target of rapamycin (mTOR) signaling in the interstitial macrophages and myofibroblasts, but rarely in injured proximal epithelial cells, CD4+ T cells, neutrophils, or endothelial cells, during the development of kidney fibrosis. Administration of rapamycin to unilateral ureteral obstruction (UUO) mice significantly suppressed the immunoreactivity of mTOR signaling, which decreased the inflammatory responses and ECM accumulation in the obstructed kidneys. Isolated macrophages from rapamycin-treated obstructed kidneys presented less inflammatory activity than vehicle groups. In vitro study confirmed that rapamycin significantly inhibited the fibrogenic activation of cultured fibroblasts (NIH3T3 cells), which was induced by the stimulation of TGF-β(1). Further experiment revealed that rapamycin did not directly inhibit the fibrogenesis of HK2 cells with aristolochic acid treatment. Our findings clarified that rapamycin can ameliorate kidney fibrosis by blocking the mTOR signaling in interstitial macrophages and myofibroblasts.
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Nagasu H, Satoh M, Kidokoro K, Nishi Y, Channon KM, Sasaki T, Kashihara N. Endothelial dysfunction promotes the transition from compensatory renal hypertrophy to kidney injury after unilateral nephrectomy in mice. Am J Physiol Renal Physiol 2012; 302:F1402-8. [PMID: 22378818 DOI: 10.1152/ajprenal.00459.2011] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Loss of functional nephrons associated with chronic kidney disease induces glomerular hyperfiltration and compensatory renal hypertrophy. We hypothesized that the endothelial nitric oxide synthase (eNOS) [soluble guanylate cyclase (sGC)] protein kinase G (PKG) pathway plays an important role in compensatory renal hypertrophy after unilateral nephrectomy. Analysis of mice subjected to unilateral nephrectomy showed increases in kidney weight-to-body weight and total protein-to-DNA ratios in wild-type but not eNOS knockout (eNOSKO) mice. Serum creatinine and blood urea nitrogen increased after nephrectomy in eNOSKO but not in wild-type mice. Furthermore, Bay 41-2272, an sGC stimulator, induced compensatory renal hypertrophy in eNOSKO mice and rescued renal function. The NO donor S-nitrosoglutathione (GSNO) and Bay 41-2272 stimulated PKG activity and induced phosphorylation of Akt protein in human proximal tubular cells. GSNO also induced phosphorylation of eukaryotic initiation factor 4E-binding protein and ribosomal protein S6. Our results highlight the importance of the eNOS-NO-PKG pathway in compensatory renal hypertrophy and suggest that reduced eNOS-NO bioavailability due to endothelial dysfunction is the underlying mechanism of failure of compensatory hypertrophy and acceleration of progressive renal dysfunction.
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Affiliation(s)
- Hajime Nagasu
- Department of Nephrology and Hypertension, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama, Japan.
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