151
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Lay AC, Hurcombe JA, Betin VMS, Barrington F, Rollason R, Ni L, Gillam L, Pearson GME, Østergaard MV, Hamidi H, Lennon R, Welsh GI, Coward RJM. Prolonged exposure of mouse and human podocytes to insulin induces insulin resistance through lysosomal and proteasomal degradation of the insulin receptor. Diabetologia 2017; 60:2299-2311. [PMID: 28852804 PMCID: PMC6448913 DOI: 10.1007/s00125-017-4394-0] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/21/2017] [Accepted: 06/28/2017] [Indexed: 12/12/2022]
Abstract
AIMS/HYPOTHESIS Podocytes are insulin-responsive cells of the glomerular filtration barrier and are key in preventing albuminuria, a hallmark feature of diabetic nephropathy. While there is evidence that a loss of insulin signalling to podocytes is detrimental, the molecular mechanisms underpinning the development of podocyte insulin resistance in diabetes remain unclear. Thus, we aimed to further investigate podocyte insulin responses early in the context of diabetic nephropathy. METHODS Conditionally immortalised human and mouse podocyte cell lines and glomeruli isolated from db/db DBA/2J mice were studied. Podocyte insulin responses were investigated with western blotting, cellular glucose uptake assays and automated fluorescent imaging of the actin cytoskeleton. Quantitative (q)RT-PCR was employed to investigate changes in mRNA. Human cell lines stably overproducing the insulin receptor (IR) and nephrin were also generated, using lentiviral constructs. RESULTS Podocytes exposed to a diabetic environment (high glucose, high insulin and the proinflammatory cytokines TNF-α and IL-6) become insulin resistant with respect to glucose uptake and activation of phosphoinositide 3-kinase (PI3K) and mitogen-activated protein kinase (MAPK) signalling. These podocytes lose expression of the IR as a direct consequence of prolonged exposure to high insulin concentrations, which causes an increase in IR protein degradation via a proteasome-dependent and bafilomycin-sensitive pathway. Reintroducing the IR into insulin-resistant human podocytes rescues upstream phosphorylation events, but not glucose uptake. Stable expression of nephrin is also required for the insulin-stimulated glucose uptake response in podocytes and for efficient insulin-stimulated remodelling of the actin cytoskeleton. CONCLUSIONS/INTERPRETATION Together, these results suggest that IR degradation, caused by high levels of insulin, drives early podocyte insulin resistance, and that both the IR and nephrin are required for full insulin sensitivity of this cell. This could be highly relevant for the development of nephropathy in individuals with type 2 diabetes, who are commonly hyperinsulinaemic in the early phases of their disease.
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Affiliation(s)
- Abigail C Lay
- Bristol Renal, Bristol Medical School, University of Bristol, Whitson Street, Bristol, BS1 3NY, UK
| | - Jenny A Hurcombe
- Bristol Renal, Bristol Medical School, University of Bristol, Whitson Street, Bristol, BS1 3NY, UK
| | - Virginie M S Betin
- Bristol Renal, Bristol Medical School, University of Bristol, Whitson Street, Bristol, BS1 3NY, UK
| | - Fern Barrington
- Bristol Renal, Bristol Medical School, University of Bristol, Whitson Street, Bristol, BS1 3NY, UK
| | - Ruth Rollason
- Bristol Renal, Bristol Medical School, University of Bristol, Whitson Street, Bristol, BS1 3NY, UK
| | - Lan Ni
- Bristol Renal, Bristol Medical School, University of Bristol, Whitson Street, Bristol, BS1 3NY, UK
| | - Lawrence Gillam
- Bristol Renal, Bristol Medical School, University of Bristol, Whitson Street, Bristol, BS1 3NY, UK
| | - Grace M E Pearson
- Bristol Renal, Bristol Medical School, University of Bristol, Whitson Street, Bristol, BS1 3NY, UK
| | - Mette V Østergaard
- Bristol Renal, Bristol Medical School, University of Bristol, Whitson Street, Bristol, BS1 3NY, UK
- Global Research, Novo Nordisk A/S, Måløv, Denmark
| | - Hellyeh Hamidi
- Wellcome Trust Centre for Cell-Matrix Research, Division of Cell Matrix Biology and Regenerative Medicine, School of Biology, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
| | - Rachel Lennon
- Wellcome Trust Centre for Cell-Matrix Research, Division of Cell Matrix Biology and Regenerative Medicine, School of Biology, Faculty of Biology, Medicine and Health, Manchester Academic Health Science Centre, University of Manchester, Manchester, UK
| | - Gavin I Welsh
- Bristol Renal, Bristol Medical School, University of Bristol, Whitson Street, Bristol, BS1 3NY, UK
| | - Richard J M Coward
- Bristol Renal, Bristol Medical School, University of Bristol, Whitson Street, Bristol, BS1 3NY, UK.
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152
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Guo H, Wang B, Li H, Ling L, Niu J, Gu Y. Glucagon-like peptide-1 analog prevents obesity-related glomerulopathy by inhibiting excessive autophagy in podocytes. Am J Physiol Renal Physiol 2017; 314:F181-F189. [PMID: 29070572 DOI: 10.1152/ajprenal.00302.2017] [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] [Indexed: 02/06/2023] Open
Abstract
To investigate the role of glucagon-like peptide-1 analog (GLP-1) in high-fat diet-induced obesity-related glomerulopathy (ORG). Male C57BL/6 mice fed a high-fat diet for 12 wk were treated with GLP-1 (200 μg/kg) or 0.9% saline for 4 wk. Fasting blood glucose and insulin and the expression of podocin, nephrin, phosphoinositide 3-kinase (PI3K), glucose transporter type (Glut4), and microtubule-associated protein 1A/1B-light chain 3 (LC3) were assayed. Glomerular morphology and podocyte foot structure were evaluated by periodic acid-Schiff staining and electron microscopy. Podocytes were treated with 150 nM GLP-1 and incubated with 400 μM palmitic acid (PA) for 12 h. The effect on autophagy was assessed by podocyte-specific Glut4 siRNA. Insulin resistance and autophagy were assayed by immunofluorescence and Western blotting. The high-fat diet resulted in weight gain, ectopic glomerular lipid accumulation, increased insulin resistance, and fusion of podophyte foot processes. The decreased translocation of Glut4 to the plasma membrane and excess autophagy seen in mice fed a high-fat diet and in PA-treated cultured podocytes were attenuated by GLP-1. Podocyte-specific Glut4 siRNA promoted autophagy, and rapamycin-enhanced autophagy worsened the podocyte injury caused by PA. Excess autophagy in podocytes was induced by inhibition of Glut4 translocation to the plasma membrane and was involved in the pathology of ORG. GLP-1 restored insulin sensitivity and ameliorated renal injury by decreasing the level of autophagy.
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Affiliation(s)
- Honglei Guo
- Division of Nephrology, The Fifth People's Hospital of Shanghai, Fudan University , Shanghai , China.,Department of Nephrology, The First Affiliated Hospital of Nanjing Medical University (Jiangsu Province Hospital), Nanjing, Jiangsu Province, China
| | - Bin Wang
- Department of Nephrology, Zhongda Hospital Southeast University, Nanjing, Jiangsu Province, China
| | - Hongmei Li
- Division of Nephrology, The Fifth People's Hospital of Shanghai, Fudan University , Shanghai , China
| | - Lilu Ling
- Division of Nephrology, The Fifth People's Hospital of Shanghai, Fudan University , Shanghai , China
| | - Jianying Niu
- Division of Nephrology, The Fifth People's Hospital of Shanghai, Fudan University , Shanghai , China
| | - Yong Gu
- Division of Nephrology, The Fifth People's Hospital of Shanghai, Fudan University , Shanghai , China.,Division of Nephrology, Huashan Hospital and Institute of Nephrology, Fudan University , Shanghai , China
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153
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Lee J, Koh A, Jeong H, Kim E, Ha TS, Saleem MA, Ryu SH. C1-Ten is a PTPase of nephrin, regulating podocyte hypertrophy through mTORC1 activation. Sci Rep 2017; 7:12346. [PMID: 28955049 PMCID: PMC5617844 DOI: 10.1038/s41598-017-12382-8] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2017] [Accepted: 09/07/2017] [Indexed: 02/06/2023] Open
Abstract
Hypertrophy is a prominent feature of damaged podocytes in diabetic kidney disease (DKD). mTORC1 hyperactivation leads to podocyte hypertrophy, but the detailed mechanism of how mTORC1 activation occurs under pathological conditions is not completely known. Moreover, reduced nephrin tyrosine phosphorylation has been observed in podocytes under pathological conditions, but the molecular mechanism linking nephrin phosphorylation and pathology is unclear so far. In this study, we observed a significant increase in C1-Ten level in diabetic kidney and in high glucose-induced damaged podocytes. C1-Ten acts as a protein tyrosine phosphatase (PTPase) at the nephrin-PI3K binding site and renders PI3K for IRS-1, thereby activating mTORC1. Furthermore, C1-Ten causes podocyte hypertrophy and proteinuria by increasing mTORC1 activity in vitro and in vivo. These findings demonstrate the relationship between nephrin dephosphorylation and the mTORC1 pathway, mediated by C1-Ten PTPase activity. We suggest that C1-Ten contributes to the pathogenesis of DKD by inducing podocyte hypertrophy under high glucose conditions.
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Affiliation(s)
- Jiyoun Lee
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
| | - Ara Koh
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
| | - Heeyoon Jeong
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
| | - Eui Kim
- Division of Integrative Biosciences and Biotechnology, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea
| | - Tae-Sun Ha
- Department of Pediatrics, College of Medicine, Chungbuk National University, Cheongju, 28644, Republic of Korea
| | - Moin A Saleem
- Academic and Children's Renal Unit, University of Bristol, Learning and Research, Southmead Hospital, Bristol, BS10 5NB, UK
| | - Sung Ho Ryu
- Department of Life Sciences, Pohang University of Science and Technology, Pohang, 37673, Republic of Korea.
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154
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Diabetic kidney disease: as easy as aPC? Blood 2017; 130:1390-1391. [DOI: 10.1182/blood-2017-08-798314] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
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155
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Sunitha MM, Srikanth L, Kumar PS, Chandrasekhar C, Sarma PVGK. Down-regulation of PAX2 promotes in vitro differentiation of podocytes from human CD34+ cells. Cell Tissue Res 2017; 370:477-488. [DOI: 10.1007/s00441-017-2680-2] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2016] [Accepted: 08/07/2017] [Indexed: 12/16/2022]
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156
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Rysz J, Gluba-Brzózka A, Franczyk B, Jabłonowski Z, Ciałkowska-Rysz A. Novel Biomarkers in the Diagnosis of Chronic Kidney Disease and the Prediction of Its Outcome. Int J Mol Sci 2017; 18:E1702. [PMID: 28777303 PMCID: PMC5578092 DOI: 10.3390/ijms18081702] [Citation(s) in RCA: 156] [Impact Index Per Article: 22.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2017] [Revised: 07/17/2017] [Accepted: 07/26/2017] [Indexed: 02/07/2023] Open
Abstract
In its early stages, symptoms of chronic kidney disease (CKD) are usually not apparent. Significant reduction of the kidney function is the first obvious sign of disease. If diagnosed early (stages 1 to 3), the progression of CKD can be altered and complications reduced. In stages 4 and 5 extensive kidney damage is observed, which usually results in end-stage renal failure. Currently, the diagnosis of CKD is made usually on the levels of blood urea and serum creatinine (sCr), however, sCr has been shown to be lacking high predictive value. Due to the development of genomics, epigenetics, transcriptomics, proteomics, and metabolomics, the introduction of novel techniques will allow for the identification of novel biomarkers in renal diseases. This review presents some new possible biomarkers in the diagnosis of CKD and in the prediction of outcome, including asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA), uromodulin, kidney injury molecule-1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), miRNA, ncRNA, and lincRNA biomarkers and proteomic and metabolomic biomarkers. Complicated pathomechanisms of CKD development and progression require not a single marker but their combination in order to mirror all types of alterations occurring in the course of this disease. It seems that in the not so distant future, conventional markers may be exchanged for new ones, however, confirmation of their efficacy, sensitivity and specificity as well as the reduction of analysis costs are required.
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Affiliation(s)
- Jacek Rysz
- Department of Nephrology, Hypertension and Family Medicine, Medical University of Lodz, Zeromskiego 113, 90-549 Lodz, Poland.
| | - Anna Gluba-Brzózka
- Department of Nephrology, Hypertension and Family Medicine, WAM Teaching Hospital, Zeromskiego 113, 90-549 Lodz, Poland.
| | - Beata Franczyk
- Department of Nephrology, Hypertension and Family Medicine, Medical University of Lodz, Zeromskiego 113, 90-549 Lodz, Poland.
| | - Zbigniew Jabłonowski
- I Department of Urology, Medical University of Lodz, Zeromskiego 113, 90-549 Lodz, Poland.
| | - Aleksandra Ciałkowska-Rysz
- Palliative Medicine Unit, Chair of Oncology, Medical University of Lodz, Zeromskiego 113, 90-549 Lodz, Poland.
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157
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Mukhi D, Nishad R, Menon RK, Pasupulati AK. Novel Actions of Growth Hormone in Podocytes: Implications for Diabetic Nephropathy. Front Med (Lausanne) 2017; 4:102. [PMID: 28748185 PMCID: PMC5506074 DOI: 10.3389/fmed.2017.00102] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2017] [Accepted: 06/26/2017] [Indexed: 02/05/2023] Open
Abstract
The kidney regulates water, electrolyte, and acid-base balance and thus maintains body homeostasis. The kidney’s potential to ensure ultrafiltered and almost protein-free urine is compromised in various metabolic and hormonal disorders such as diabetes mellitus (DM). Diabetic nephropathy (DN) accounts for ~20–40% of mortality in DM. Proteinuria, a hallmark of renal glomerular diseases, indicates injury to the glomerular filtration barrier (GFB). The GFB is composed of glomerular endothelium, basement membrane, and podocytes. Podocytes are terminally differentiated epithelial cells with limited ability to replicate. Podocyte shape and number are both critical for the integrity and function of the GFB. Podocytes are vulnerable to various noxious stimuli prevalent in a diabetic milieu that could provoke podocytes to undergo changes to their unique architecture and function. Effacement of podocyte foot process is a typical morphological alteration associated with proteinuria. The dedifferentiation of podocytes from epithelial-to-mesenchymal phenotype and consequential loss results in proteinuria. Poorly controlled type 1 DM is associated with elevated levels of circulating growth hormone (GH), which is implicated in the pathophysiology of various diabetic complications including DN. Recent studies demonstrate that functional GH receptors are expressed in podocytes and that GH may exert detrimental effects on the podocyte. In this review, we summarize recent advances that shed light on actions of GH on the podocyte that could play a role in the pathogenesis of DN.
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Affiliation(s)
- Dhanunjay Mukhi
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, India
| | - Rajkishor Nishad
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, India
| | - Ram K Menon
- Department of Pediatric Endocrinology and Physiology, University of Michigan, Ann Arbor, MI, United States
| | - Anil Kumar Pasupulati
- Department of Biochemistry, School of Life Sciences, University of Hyderabad, Hyderabad, India
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158
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Signal integration at the PI3K-p85-XBP1 hub endows coagulation protease activated protein C with insulin-like function. Blood 2017; 130:1445-1455. [PMID: 28687614 DOI: 10.1182/blood-2017-02-767921] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2017] [Accepted: 06/27/2017] [Indexed: 12/11/2022] Open
Abstract
Coagulation proteases have increasingly recognized functions beyond hemostasis and thrombosis. Disruption of activated protein C (aPC) or insulin signaling impair function of podocytes and ultimately cause dysfunction of the glomerular filtration barrier and diabetic kidney disease (DKD). We here show that insulin and aPC converge on a common spliced-X-box binding protein-1 (sXBP1) signaling pathway to maintain endoplasmic reticulum (ER) homeostasis. Analogous to insulin, physiological levels of aPC maintain ER proteostasis in DKD. Accordingly, genetically impaired protein C activation exacerbates maladaptive ER response, whereas genetic or pharmacological restoration of aPC maintains ER proteostasis in DKD models. Importantly, in mice with podocyte-specific deficiency of insulin receptor (INSR), aPC selectively restores the activity of the cytoprotective ER-transcription factor sXBP1 by temporally targeting INSR downstream signaling intermediates, the regulatory subunits of PI3Kinase, p85α and p85β. Genome-wide mapping of condition-specific XBP1-transcriptional regulatory patterns confirmed that concordant unfolded protein response target genes are involved in maintenance of ER proteostasis by both insulin and aPC. Thus, aPC efficiently employs disengaged insulin signaling components to reconfigure ER signaling and restore proteostasis. These results identify ER reprogramming as a novel hormonelike function of coagulation proteases and demonstrate that targeting insulin signaling intermediates may be a feasible therapeutic approach ameliorating defective insulin signaling.
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159
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Bettaieb A, Koike S, Chahed S, Zhao Y, Bachaalany S, Hashoush N, Graham J, Huma F, Havel PJ, Gruzdev A, Zeldin DC, Hammock BD, Haj FG. Podocyte-specific soluble epoxide hydrolase deficiency in mice attenuates acute kidney injury. FEBS J 2017; 284:1970-1986. [PMID: 28485854 PMCID: PMC5515292 DOI: 10.1111/febs.14100] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Revised: 03/22/2017] [Accepted: 05/04/2017] [Indexed: 12/16/2022]
Abstract
Podocytes play an important role in maintaining glomerular function, and podocyte injury is a significant component in the pathogenesis of proteinuria. Soluble epoxide hydrolase (sEH) is a cytosolic enzyme whose genetic deficiency and pharmacological inhibition have beneficial effects on renal function, but its role in podocytes remains unexplored. The objective of this study was to investigate the contribution of sEH in podocytes to lipopolysaccharide (LPS)-induced kidney injury. We report increased sEH transcript and protein expression in murine podocytes upon LPS challenge. To determine the function of sEH in podocytes in vivo we generated podocyte-specific sEH-deficient (pod-sEHKO) mice. Following LPS challenge, podocyte sEH-deficient mice exhibited lower kidney injury, proteinuria, and blood urea nitrogen concentrations than controls suggestive of preserved renal function. Also, renal mRNA and serum concentrations of inflammatory cytokines IL-6, IL-1β, and TNFα were significantly lower in LPS-treated pod-sEHKO than control mice. Moreover, podocyte sEH deficiency was associated with decreased LPS-induced NF-κB and MAPK activation and attenuated endoplasmic reticulum stress. Furthermore, the protective effects of podocyte sEH deficiency in vivo were recapitulated in E11 murine podocytes treated with a selective sEH pharmacological inhibitor. Altogether, these findings identify sEH in podocytes as a contributor to signaling events in acute renal injury and suggest that sEH inhibition may be of therapeutic value in proteinuria. ENZYMES Soluble epoxide hydrolase: EC 3.3.2.10.
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Affiliation(s)
- Ahmed Bettaieb
- Department of Nutrition, University of California Davis, One Shields Ave, Davis, CA 95616
- Department of Nutrition, University of Tennessee-Knoxville, Knoxville, TN 37996
| | - Shinichiro Koike
- Department of Nutrition, University of California Davis, One Shields Ave, Davis, CA 95616
| | - Samah Chahed
- Department of Nutrition, University of California Davis, One Shields Ave, Davis, CA 95616
| | - Yi Zhao
- Department of Nutrition, University of Tennessee-Knoxville, Knoxville, TN 37996
| | - Santana Bachaalany
- Department of Nutrition, University of California Davis, One Shields Ave, Davis, CA 95616
| | - Nader Hashoush
- Department of Nutrition, University of California Davis, One Shields Ave, Davis, CA 95616
| | - James Graham
- Department of Nutrition, University of California Davis, One Shields Ave, Davis, CA 95616
| | - Fatima Huma
- Department of Pathology, University of Alabama at Birmingham, Birmingham, AL 35233
| | - Peter J. Havel
- Department of Nutrition, University of California Davis, One Shields Ave, Davis, CA 95616
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California Davis, One Shields Ave, Davis, CA 95616
| | - Artiom Gruzdev
- Division of Intramural Research, National Institute of Environmental Health Sciences, North Carolina, NC 27709
| | - Darryl C. Zeldin
- Division of Intramural Research, National Institute of Environmental Health Sciences, North Carolina, NC 27709
| | - Bruce D. Hammock
- Department of Entomology and Nematology, University of California-Davis, Davis, CA 95616
- Comprehensive Cancer Center, University of California Davis, Sacramento, CA 95817
| | - Fawaz G. Haj
- Department of Nutrition, University of California Davis, One Shields Ave, Davis, CA 95616
- Comprehensive Cancer Center, University of California Davis, Sacramento, CA 95817
- Division of Endocrinology, Diabetes, and Metabolism, Department of Internal Medicine, University of California Davis, Sacramento, CA 95817
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160
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Wang XX, Luo Y, Wang D, Adorini L, Pruzanski M, Dobrinskikh E, Levi M. A dual agonist of farnesoid X receptor (FXR) and the G protein-coupled receptor TGR5, INT-767, reverses age-related kidney disease in mice. J Biol Chem 2017; 292:12018-12024. [PMID: 28596381 DOI: 10.1074/jbc.c117.794982] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2017] [Revised: 06/07/2017] [Indexed: 11/06/2022] Open
Abstract
Even in healthy individuals, renal function gradually declines during aging. However, an observed variation in the rate of this decline has raised the possibility of slowing or delaying age-related kidney disease. One of the most successful interventional measures that slows down and delays age-related kidney disease is caloric restriction. We undertook the present studies to search for potential factors that are regulated by caloric restriction and act as caloric restriction mimetics. Based on our prior studies with the bile acid-activated nuclear hormone receptor farnesoid X receptor (FXR) and G protein-coupled membrane receptor TGR5 that demonstrated beneficial effects of FXR and TGR5 activation in the kidney, we reasoned that FXR and TGR5 could be excellent candidates. We therefore determined the effects of aging and caloric restriction on the expression of FXR and TGR5 in the kidney. We found that FXR and TGR5 expression levels are decreased in the aging kidney and that caloric restriction prevents these age-related decreases. Interestingly, in long-lived Ames dwarf mice, renal FXR and TGR5 expression levels were also increased. A 2-month treatment of 22-month-old C57BL/6J mice with the FXR-TGR5 dual agonist INT-767 induced caloric restriction-like effects and reversed age-related increases in proteinuria, podocyte injury, fibronectin accumulation, TGF-β expression, and, most notably, age-related impairments in mitochondrial biogenesis and mitochondrial function. Furthermore, in podocytes cultured in serum obtained from old mice, INT-767 prevented the increases in the proinflammatory markers TNF-α, toll-like receptor 2 (TLR2), and TLR4. In summary, our results indicate that FXR and TGR5 may play an important role in modulation of age-related kidney disease.
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Affiliation(s)
- Xiaoxin X Wang
- Division of Renal Diseases and Hypertension, Department of Medicine, Denver Veterans Affairs Medical Center and University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045
| | - Yuhuan Luo
- Division of Renal Diseases and Hypertension, Department of Medicine, Denver Veterans Affairs Medical Center and University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045
| | - Dong Wang
- Division of Renal Diseases and Hypertension, Department of Medicine, Denver Veterans Affairs Medical Center and University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045
| | | | | | - Evgenia Dobrinskikh
- Division of Renal Diseases and Hypertension, Department of Medicine, Denver Veterans Affairs Medical Center and University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045
| | - Moshe Levi
- Division of Renal Diseases and Hypertension, Department of Medicine, Denver Veterans Affairs Medical Center and University of Colorado Anschutz Medical Campus, Aurora, Colorado 80045.
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161
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Rogacka D, Audzeyenka I, Rachubik P, Rychłowski M, Kasztan M, Jankowski M, Angielski S, Piwkowska A. Insulin increases filtration barrier permeability via TRPC6-dependent activation of PKGIα signaling pathways. Biochim Biophys Acta Mol Basis Dis 2017; 1863:1312-1325. [DOI: 10.1016/j.bbadis.2017.03.002] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2016] [Revised: 02/04/2017] [Accepted: 03/01/2017] [Indexed: 11/25/2022]
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162
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Mollaee M, Fülöp T, Abdul Salim S, Hamrahian M. Idiopathic nodular glomerulosclerosis in a chronic marijuana user; a case report and review of the literature. J Nephropathol 2017. [DOI: 10.15171/jnp.2017.46] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
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163
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Kuczkowski A, Brinkkoetter PT. Metabolism and homeostasis in the kidney: metabolic regulation through insulin signaling in the kidney. Cell Tissue Res 2017; 369:199-210. [DOI: 10.1007/s00441-017-2619-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2017] [Accepted: 03/22/2017] [Indexed: 02/07/2023]
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164
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González N, Prieto I, del Puerto-Nevado L, Portal-Nuñez S, Ardura JA, Corton M, Fernández-Fernández B, Aguilera O, Gomez-Guerrero C, Mas S, Moreno JA, Ruiz-Ortega M, Sanz AB, Sanchez-Niño MD, Rojo F, Vivanco F, Esbrit P, Ayuso C, Alvarez-Llamas G, Egido J, García-Foncillas J, Ortiz A. 2017 update on the relationship between diabetes and colorectal cancer: epidemiology, potential molecular mechanisms and therapeutic implications. Oncotarget 2017; 8:18456-18485. [PMID: 28060743 PMCID: PMC5392343 DOI: 10.18632/oncotarget.14472] [Citation(s) in RCA: 121] [Impact Index Per Article: 17.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/07/2016] [Accepted: 12/26/2016] [Indexed: 02/06/2023] Open
Abstract
Worldwide deaths from diabetes mellitus (DM) and colorectal cancer increased by 90% and 57%, respectively, over the past 20 years. The risk of colorectal cancer was estimated to be 27% higher in patients with type 2 DM than in non-diabetic controls. However, there are potential confounders, information from lower income countries is scarce, across the globe there is no correlation between DM prevalence and colorectal cancer incidence and the association has evolved over time, suggesting the impact of additional environmental factors. The clinical relevance of these associations depends on understanding the mechanism involved. Although evidence is limited, insulin use has been associated with increased and metformin with decreased incidence of colorectal cancer. In addition, colorectal cancer shares some cellular and molecular pathways with diabetes target organ damage, exemplified by diabetic kidney disease. These include epithelial cell injury, activation of inflammation and Wnt/β-catenin pathways and iron homeostasis defects, among others. Indeed, some drugs have undergone clinical trials for both cancer and diabetic kidney disease. Genome-wide association studies have identified diabetes-associated genes (e.g. TCF7L2) that may also contribute to colorectal cancer. We review the epidemiological evidence, potential pathophysiological mechanisms and therapeutic implications of the association between DM and colorectal cancer. Further studies should clarify the worldwide association between DM and colorectal cancer, strengthen the biological plausibility of a cause-and-effect relationship through characterization of the molecular pathways involved, search for specific molecular signatures of colorectal cancer under diabetic conditions, and eventually explore DM-specific strategies to prevent or treat colorectal cancer.
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Affiliation(s)
- Nieves González
- Renal, Vascular and Diabetes Research Laboratory, IIS-Fundacion Jimenez Diaz-UAM, Spanish Biomedical Research Network in Diabetes and Associated Metabolic Disorders (CIBERDEM), Madrid, Spain
| | - Isabel Prieto
- Radiation Oncology, Oncohealth Institute, IIS-Fundacion Jimenez Diaz-UAM, Madrid, Spain
| | - Laura del Puerto-Nevado
- Translational Oncology Division, Oncohealth Institute, IIS-Fundacion Jimenez Diaz-UAM, Madrid, Spain
| | - Sergio Portal-Nuñez
- Bone and Mineral Metabolism laboratory, IIS-Fundacion Jimenez Diaz-UAM, Madrid, Spain
| | - Juan Antonio Ardura
- Bone and Mineral Metabolism laboratory, IIS-Fundacion Jimenez Diaz-UAM, Madrid, Spain
| | - Marta Corton
- Genetics, IIS-Fundacion Jimenez Diaz-UAM, Madrid, Spain
| | | | - Oscar Aguilera
- Translational Oncology Division, Oncohealth Institute, IIS-Fundacion Jimenez Diaz-UAM, Madrid, Spain
| | | | - Sebastián Mas
- Nephrology, IIS-Fundacion Jimenez Diaz-UAM, Madrid, Spain
| | | | | | - Ana Belen Sanz
- Nephrology, IIS-Fundacion Jimenez Diaz-UAM, Madrid, Spain
- REDINREN, Madrid, Spain
| | | | - Federico Rojo
- Pathology, IIS-Fundacion Jimenez Diaz-UAM, Madrid, Spain
| | | | - Pedro Esbrit
- Bone and Mineral Metabolism laboratory, IIS-Fundacion Jimenez Diaz-UAM, Madrid, Spain
| | - Carmen Ayuso
- Genetics, IIS-Fundacion Jimenez Diaz-UAM, Madrid, Spain
| | | | - Jesús Egido
- Renal, Vascular and Diabetes Research Laboratory, IIS-Fundacion Jimenez Diaz-UAM, Spanish Biomedical Research Network in Diabetes and Associated Metabolic Disorders (CIBERDEM), Madrid, Spain
- Nephrology, IIS-Fundacion Jimenez Diaz-UAM, Madrid, Spain
| | - Jesús García-Foncillas
- Translational Oncology Division, Oncohealth Institute, IIS-Fundacion Jimenez Diaz-UAM, Madrid, Spain
| | - Alberto Ortiz
- Nephrology, IIS-Fundacion Jimenez Diaz-UAM, Madrid, Spain
- REDINREN, Madrid, Spain
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165
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Falkevall A, Mehlem A, Palombo I, Heller Sahlgren B, Ebarasi L, He L, Ytterberg AJ, Olauson H, Axelsson J, Sundelin B, Patrakka J, Scotney P, Nash A, Eriksson U. Reducing VEGF-B Signaling Ameliorates Renal Lipotoxicity and Protects against Diabetic Kidney Disease. Cell Metab 2017; 25:713-726. [PMID: 28190774 DOI: 10.1016/j.cmet.2017.01.004] [Citation(s) in RCA: 122] [Impact Index Per Article: 17.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2016] [Revised: 11/25/2016] [Accepted: 01/10/2017] [Indexed: 12/14/2022]
Abstract
Diabetic kidney disease (DKD) is the most common cause of severe renal disease, and few treatment options are available today that prevent the progressive loss of renal function. DKD is characterized by altered glomerular filtration and proteinuria. A common observation in DKD is the presence of renal steatosis, but the mechanism(s) underlying this observation and to what extent they contribute to disease progression are unknown. Vascular endothelial growth factor B (VEGF-B) controls muscle lipid accumulation through regulation of endothelial fatty acid transport. Here, we demonstrate in experimental mouse models of DKD that renal VEGF-B expression correlates with the severity of disease. Inhibiting VEGF-B signaling in DKD mouse models reduces renal lipotoxicity, re-sensitizes podocytes to insulin signaling, inhibits the development of DKD-associated pathologies, and prevents renal dysfunction. Further, we show that elevated VEGF-B levels are found in patients with DKD, suggesting that VEGF-B antagonism represents a novel approach to treat DKD.
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Affiliation(s)
- Annelie Falkevall
- Division of Vascular Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Annika Mehlem
- Division of Vascular Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Isolde Palombo
- Division of Vascular Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Benjamin Heller Sahlgren
- Division of Vascular Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 171 77 Stockholm, Sweden
| | - Lwaki Ebarasi
- Division of Vascular Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 171 77 Stockholm, Sweden; Department of Immunology, Genetics, and Pathology, Rudbeck Laboratory, Uppsala University, 751 85 Uppsala, Sweden; Division of Renal Medicine, Department of Clinical Sciences, Intervention, and Technology, Karolinska Institutet, 141 86 Stockholm, Sweden
| | - Liqun He
- Department of Immunology, Genetics, and Pathology, Rudbeck Laboratory, Uppsala University, 751 85 Uppsala, Sweden
| | - A Jimmy Ytterberg
- Division of Physiological Chemistry I, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 171 77 Stockholm, Sweden; Rheumatology Unit, Department of Medicine, Solna, Karolinska Institutet, 171 76 Stockholm, Sweden
| | - Hannes Olauson
- Division of Renal Medicine, Department of Clinical Sciences, Intervention, and Technology, Karolinska Institutet, 141 86 Stockholm, Sweden
| | - Jonas Axelsson
- Division of Vascular Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 171 77 Stockholm, Sweden; Center for Apheresis and Stem Cell Handling, Karolinska University Hospital, 141 86 Stockholm, Sweden
| | - Birgitta Sundelin
- Department of Oncology-Pathology, Karolinska Institutet and Karolinska University Hospital, 171 76 Stockholm, Sweden
| | - Jaakko Patrakka
- KI/AZ Integrated CardioMetabolic Center (ICMC), Department of Laboratory Medicine, Karolinska Institutet at Karolinska University Hospital Huddinge, 141 57 Huddinge, Sweden
| | | | | | - Ulf Eriksson
- Division of Vascular Biology, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, 171 77 Stockholm, Sweden.
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166
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Oyarzún C, Garrido W, Alarcón S, Yáñez A, Sobrevia L, Quezada C, San Martín R. Adenosine contribution to normal renal physiology and chronic kidney disease. Mol Aspects Med 2017; 55:75-89. [PMID: 28109856 DOI: 10.1016/j.mam.2017.01.004] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2016] [Revised: 01/11/2017] [Accepted: 01/13/2017] [Indexed: 12/12/2022]
Abstract
Adenosine is a nucleoside that is particularly interesting to many scientific and clinical communities as it has important physiological and pathophysiological roles in the kidney. The distribution of adenosine receptors has only recently been elucidated; therefore it is likely that more biological roles of this nucleoside will be unveiled in the near future. Since the discovery of the involvement of adenosine in renal vasoconstriction and regulation of local renin production, further evidence has shown that adenosine signaling is also involved in the tubuloglomerular feedback mechanism, sodium reabsorption and the adaptive response to acute insults, such as ischemia. However, the most interesting finding was the increased adenosine levels in chronic kidney diseases such as diabetic nephropathy and also in non-diabetic animal models of renal fibrosis. When adenosine is chronically increased its signaling via the adenosine receptors may change, switching to a state that induces renal damage and produces phenotypic changes in resident cells. This review discusses the physiological and pathophysiological roles of adenosine and pays special attention to the mechanisms associated with switching homeostatic nucleoside levels to increased adenosine production in kidneys affected by CKD.
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Affiliation(s)
- Carlos Oyarzún
- Institute of Biochemistry and Microbiology, Science Faculty, Universidad Austral de Chile, Valdivia, Chile
| | - Wallys Garrido
- Institute of Biochemistry and Microbiology, Science Faculty, Universidad Austral de Chile, Valdivia, Chile
| | - Sebastián Alarcón
- Institute of Biochemistry and Microbiology, Science Faculty, Universidad Austral de Chile, Valdivia, Chile
| | - Alejandro Yáñez
- Institute of Biochemistry and Microbiology, Science Faculty, Universidad Austral de Chile, Valdivia, Chile
| | - Luis Sobrevia
- Cellular and Molecular Physiology Laboratory (CMPL), Division of Obstetrics and Gynaecology, School of Medicine, Faculty of Medicine, Pontificia Universidad Católica de Chile, Santiago 8330024, Chile; Department of Physiology, Faculty of Pharmacy, Universidad de Sevilla, Seville E-41012, Spain; University of Queensland Centre for Clinical Research (UQCCR), Faculty of Medicine and Biomedical Sciences, University of Queensland, Herston QLD 4029, Queensland, Australia
| | - Claudia Quezada
- Institute of Biochemistry and Microbiology, Science Faculty, Universidad Austral de Chile, Valdivia, Chile
| | - Rody San Martín
- Institute of Biochemistry and Microbiology, Science Faculty, Universidad Austral de Chile, Valdivia, Chile.
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167
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Escribano O, Beneit N, Rubio-Longás C, López-Pastor AR, Gómez-Hernández A. The Role of Insulin Receptor Isoforms in Diabetes and Its Metabolic and Vascular Complications. J Diabetes Res 2017; 2017:1403206. [PMID: 29201918 PMCID: PMC5671728 DOI: 10.1155/2017/1403206] [Citation(s) in RCA: 33] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2017] [Revised: 09/12/2017] [Accepted: 09/25/2017] [Indexed: 12/18/2022] Open
Abstract
The insulin receptor (IR) presents by alternative splicing two isoforms: IRA and IRB. The differential physiological and pathological role of both isoforms is not completely known, and it is determinant the different binding affinity for insulin-like growth factor. IRB is more abundant in adult tissues and it exerts mainly the metabolic actions of insulin, whereas IRA is mainly expressed in fetal and prenatal period and exerts mitogenic actions. However, the change in the expression profile of both IR isoforms and its dysregulation are associated with the development of different pathologies, such as cancer, insulin resistance, diabetes, obesity, and atherosclerosis. In some of them, there is a significant increase of IRA/IRB ratio conferring a proliferative and migratory advantage to different cell types and favouring IGF-II actions with a sustained detriment in the metabolic effects of insulin. This review discussed specifically the role of IR isoforms as well as IGF-IR in diabetes and its associated complications as obesity and atherosclerosis. Future research with new IR modulators might be considered as possible targets to improve the treatment of diabetes and its associated complications.
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Affiliation(s)
- O. Escribano
- Biochemistry and Molecular Biology II Department, School of Pharmacy, Complutense University of Madrid, Madrid, Spain
- Health Research Institute of San Carlos Clinic Hospital (IdISSC), Madrid, Spain
- CIBER of Diabetes and Associated Metabolic Diseases, Madrid, Spain
| | - N. Beneit
- Biochemistry and Molecular Biology II Department, School of Pharmacy, Complutense University of Madrid, Madrid, Spain
- Health Research Institute of San Carlos Clinic Hospital (IdISSC), Madrid, Spain
- CIBER of Diabetes and Associated Metabolic Diseases, Madrid, Spain
| | - C. Rubio-Longás
- Biochemistry and Molecular Biology II Department, School of Pharmacy, Complutense University of Madrid, Madrid, Spain
| | - A. R. López-Pastor
- Biochemistry and Molecular Biology II Department, School of Pharmacy, Complutense University of Madrid, Madrid, Spain
| | - A. Gómez-Hernández
- Biochemistry and Molecular Biology II Department, School of Pharmacy, Complutense University of Madrid, Madrid, Spain
- Health Research Institute of San Carlos Clinic Hospital (IdISSC), Madrid, Spain
- CIBER of Diabetes and Associated Metabolic Diseases, Madrid, Spain
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168
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Dai H, Liu Q, Liu B. Research Progress on Mechanism of Podocyte Depletion in Diabetic Nephropathy. J Diabetes Res 2017; 2017:2615286. [PMID: 28791309 PMCID: PMC5534294 DOI: 10.1155/2017/2615286] [Citation(s) in RCA: 178] [Impact Index Per Article: 25.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/23/2016] [Revised: 02/05/2017] [Accepted: 03/05/2017] [Indexed: 12/13/2022] Open
Abstract
Diabetic nephropathy (DN) together with glomerular hyperfiltration has been implicated in the development of diabetic microangiopathy in the initial stage of diabetic diseases. Increased amounts of urinary protein in DN may be associated with functional and morphological alterations of podocyte, mainly including podocyte hypertrophy, epithelial-mesenchymal transdifferentiation (EMT), podocyte detachment, and podocyte apoptosis. Accumulating studies have revealed that disruption in multiple renal signaling pathways had been critical in the progression of these pathological damages, such as adenosine monophosphate-activated kinase signaling pathways (AMPK), wnt/β-catenin signaling pathways, endoplasmic reticulum stress-related signaling pathways, mammalian target of rapamycin (mTOR)/autophagy pathway, and Rho GTPases. In this review, we highlight new molecular insights underlying podocyte injury in the progression of DN, which offer new therapeutic targets to develop important renoprotective treatments for DN over the next decade.
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Affiliation(s)
- Haoran Dai
- Department of Nephrology, Shunyi Branch, Beijing Hospital of Traditional Chinese Medicine, Station East 5, Shunyi District, Beijing 101300, China
| | - Qingquan Liu
- Department of Nephrology, Shunyi Branch, Beijing Hospital of Traditional Chinese Medicine, Station East 5, Shunyi District, Beijing 101300, China
- Beijing Hospital of Traditional Chinese Medicine Affiliated to Capital Medical University, 23 Meishuguanhou Street, Dongcheng District, Beijing 100010, China
- *Qingquan Liu: and
| | - Baoli Liu
- Department of Nephrology, Shunyi Branch, Beijing Hospital of Traditional Chinese Medicine, Station East 5, Shunyi District, Beijing 101300, China
- Beijing Hospital of Traditional Chinese Medicine Affiliated to Capital Medical University, 23 Meishuguanhou Street, Dongcheng District, Beijing 100010, China
- *Baoli Liu:
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169
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Sun J, Li ZP, Zhang RQ, Zhang HM. Repression of miR-217 protects against high glucose-induced podocyte injury and insulin resistance by restoring PTEN-mediated autophagy pathway. Biochem Biophys Res Commun 2016; 483:318-324. [PMID: 28017719 DOI: 10.1016/j.bbrc.2016.12.145] [Citation(s) in RCA: 43] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2016] [Accepted: 12/21/2016] [Indexed: 12/20/2022]
Abstract
Podocyte damage is the initial hallmark of diabetic nephropathy (DN), leading to the increasing morbidity and mortality in diabetic patients. Recent researches have corroborated the critical roles of miRNAs in the pathological progression of DN. Here, elevation of miR-217 was verified in high glucose (HG)-stimulated podocytes. Moreover, blocking miR-217 expression antagonized HG-induced cell injury by attenuating the adverse role of HG on cell viability and inhibiting ROS levels and cell apoptosis. Simultaneously, miR-217 repression restored HG-disrupted insulin resistance by elevating glucose uptake and nephrin expression, an essential component for insulin-induced glucose uptake. Mechanism assay substantiated the defective autophagy in HG-treated podocytes, which was resumed by miR-217 cessation. Importantly, suppressing autophagy pathway with 3-MA alleviated the protective roles of miR-217 down-regulation in podocyte injury and insulin resistance. Luciferase reporter analysis confirmed that PTEN was a target of miR-217 in podocytes. Additionally, blocking PTEN expression restrained autophagy restoration in miR-217-decreased cells. Furthermore, PTEN down-regulation attenuated the beneficial role of miR-217 suppression in HG-induced injury and insulin resistance. Together, this study manifests that miR-217inhibition can protectively antagonize HG-induced podocyte damage and insulin resistance by restoring the defective autophagy pathway via targeting PTEN, representing a novel and promising therapeutic target against diabetic nephropathy.
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Affiliation(s)
- Juan Sun
- School of Nursing, Xinxiang Medical University, Xinxiang, Henan, 453003, PR China
| | - Zhao Pin Li
- School of International Education, Xin Xiang Medical University, Xinxiang, Henan, 453003, PR China
| | - Rui Qin Zhang
- School of Nursing, Xinxiang Medical University, Xinxiang, Henan, 453003, PR China
| | - Hui Min Zhang
- School of Nursing, Xinxiang Medical University, Xinxiang, Henan, 453003, PR China.
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170
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Wasik AA, Dumont V, Tienari J, Nyman TA, Fogarty CL, Forsblom C, Lehto M, Lehtonen E, Groop PH, Lehtonen S. Septin 7 reduces nonmuscle myosin IIA activity in the SNAP23 complex and hinders GLUT4 storage vesicle docking and fusion. Exp Cell Res 2016; 350:336-348. [PMID: 28011197 PMCID: PMC5243148 DOI: 10.1016/j.yexcr.2016.12.010] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 12/10/2016] [Accepted: 12/17/2016] [Indexed: 12/28/2022]
Abstract
Glomerular epithelial cells, podocytes, are insulin responsive and can develop insulin resistance. Here, we demonstrate that the small GTPase septin 7 forms a complex with nonmuscle myosin heavy chain IIA (NMHC-IIA; encoded by MYH9), a component of the nonmuscle myosin IIA (NM-IIA) hexameric complex. We observed that knockdown of NMHC-IIA decreases insulin-stimulated glucose uptake into podocytes. Both septin 7 and NM-IIA associate with SNAP23, a SNARE protein involved in GLUT4 storage vesicle (GSV) docking and fusion with the plasma membrane. We observed that insulin decreases the level of septin 7 and increases the activity of NM-IIA in the SNAP23 complex, as visualized by increased phosphorylation of myosin regulatory light chain. Also knockdown of septin 7 increases the activity of NM-IIA in the complex. The activity of NM-IIA is increased in diabetic rat glomeruli and cultured human podocytes exposed to macroalbuminuric sera from patients with type 1 diabetes. Collectively, the data suggest that the activity of NM-IIA in the SNAP23 complex plays a key role in insulin-stimulated glucose uptake into podocytes. Furthermore, we observed that septin 7 reduces the activity of NM-IIA in the SNAP23 complex and thereby hinders GSV docking and fusion with the plasma membrane. Septin 7, nonmuscle myosin heavy chain IIA (NMHC-IIA) and SNAP23 form a complex. Knockdown of septin 7 increases NM-IIA activity in the SNAP23 complex. Insulin decreases septin 7 level and increases NM-IIA activity in the SNAP23 complex. Septin 7 hinders GSV docking/fusion by reducing NM-IIA activity in the SNAP23 complex.
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Affiliation(s)
- Anita A Wasik
- Department of Pathology, University of Helsinki, 00014 Helsinki, Finland
| | - Vincent Dumont
- Department of Pathology, University of Helsinki, 00014 Helsinki, Finland
| | - Jukka Tienari
- Department of Pathology, University of Helsinki and Helsinki University Hospital, 00290 Helsinki, 05850 Hyvinkää, Finland
| | - Tuula A Nyman
- Institute of Biotechnology, University of Helsinki, 00014 Helsinki, Finland
| | - Christopher L Fogarty
- Folkhälsan Institute of Genetics, Folkhälsan Research Center, 00290 Helsinki, Finland; Abdominal Center Nephrology, University of Helsinki and Helsinki University Hospital, 000290 Helsinki, Finland; Diabetes&Obesity Research Program, Research Program´s Unit, 00014 University of Helsinki, Finland
| | - Carol Forsblom
- Folkhälsan Institute of Genetics, Folkhälsan Research Center, 00290 Helsinki, Finland; Abdominal Center Nephrology, University of Helsinki and Helsinki University Hospital, 000290 Helsinki, Finland; Diabetes&Obesity Research Program, Research Program´s Unit, 00014 University of Helsinki, Finland
| | - Markku Lehto
- Folkhälsan Institute of Genetics, Folkhälsan Research Center, 00290 Helsinki, Finland; Abdominal Center Nephrology, University of Helsinki and Helsinki University Hospital, 000290 Helsinki, Finland; Diabetes&Obesity Research Program, Research Program´s Unit, 00014 University of Helsinki, Finland
| | - Eero Lehtonen
- Department of Pathology, University of Helsinki, 00014 Helsinki, Finland; Laboratory Animal Centre, University of Helsinki, 00014 Helsinki, Finland
| | - Per-Henrik Groop
- Folkhälsan Institute of Genetics, Folkhälsan Research Center, 00290 Helsinki, Finland; Abdominal Center Nephrology, University of Helsinki and Helsinki University Hospital, 000290 Helsinki, Finland; Diabetes&Obesity Research Program, Research Program´s Unit, 00014 University of Helsinki, Finland; Baker IDI Heart & Diabetes Institute, 3004 Melbourne, Australia
| | - Sanna Lehtonen
- Department of Pathology, University of Helsinki, 00014 Helsinki, Finland.
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171
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Abstract
Pericytes are a heterogeneous population of cells located in the blood vessel wall. They were first identified in the 19th century by Rouget, however their biological role and potential for drug targeting have taken time to be recognised. Isolation of pericytes from several different tissues has allowed a better phenotypic and functional characterization. These findings revealed a tissue-specific, multi-functional group of cells with multilineage potential. Given this emerging evidence, pericytes have acquired specific roles in pathobiological events in vascular diseases. In this review article, we will provide a compelling overview of the main diseases in which pericytes are involved, from well-established mechanisms to the latest findings. Pericyte involvement in diabetes and cancer will be discussed extensively. In the last part of the article we will review therapeutic approaches for these diseases in light of the recently acquired knowledge. To unravel pericyte-related vascular pathobiological events is pivotal not only for more tailored treatments of disease but also to establish pericytes as a therapeutic tool.
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172
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Lizotte F, Denhez B, Guay A, Gévry N, Côté AM, Geraldes P. Persistent Insulin Resistance in Podocytes Caused by Epigenetic Changes of SHP-1 in Diabetes. Diabetes 2016; 65:3705-3717. [PMID: 27585521 DOI: 10.2337/db16-0254] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Accepted: 08/26/2016] [Indexed: 11/13/2022]
Abstract
Poor glycemic control profoundly affects protein expression and the cell signaling action that contributes to glycemic memory and irreversible progression of diabetic nephropathy (DN). We demonstrate that SHP-1 is elevated in podocytes of diabetic mice, causing insulin unresponsiveness and DN. Thus, sustained SHP-1 expression caused by hyperglycemia despite systemic glucose normalization could contribute to the glycemic memory effect in DN. Microalbuminuria, glomerular filtration rate, mesangial cell expansion, and collagen type IV and transforming growth factor-β expression were significantly increased in diabetic Ins2+/C96Y mice compared with nondiabetic Ins2+/+ mice and remained elevated despite glucose normalization with insulin implants. A persistent increase of SHP-1 expression in podocytes despite normalization of systemic glucose levels was associated with sustained inhibition of the insulin signaling pathways. In cultured podocytes, high glucose levels increased mRNA, protein expression, and phosphatase activity of SHP-1, which remained elevated despite glucose concentration returning to normal, causing persistent insulin receptor-β inhibition. Histone posttranslational modification analysis showed that the promoter region of SHP-1 was enriched with H3K4me1 and H3K9/14ac in diabetic glomeruli and podocytes, which remained elevated despite glucose level normalization. Hyperglycemia induces SHP-1 promoter epigenetic modifications, causing its persistent expression and activity and leading to insulin resistance, podocyte dysfunction, and DN.
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MESH Headings
- Animals
- Cell Line
- Diabetes Mellitus, Experimental/genetics
- Diabetes Mellitus, Experimental/metabolism
- Diabetic Nephropathies/genetics
- Diabetic Nephropathies/metabolism
- Epigenesis, Genetic/genetics
- Glomerular Filtration Rate/physiology
- Hyperglycemia/genetics
- Hyperglycemia/metabolism
- Immunohistochemistry
- Insulin Resistance/genetics
- Insulin Resistance/physiology
- Kidney Glomerulus/metabolism
- Male
- Mice
- Mice, Inbred C57BL
- Microscopy, Electron, Transmission
- Podocytes/metabolism
- Promoter Regions, Genetic/genetics
- Protein Tyrosine Phosphatase, Non-Receptor Type 6/genetics
- Receptor, Insulin/genetics
- Receptor, Insulin/metabolism
- Signal Transduction/genetics
- Signal Transduction/physiology
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Affiliation(s)
- Farah Lizotte
- Research Center of CHU de Sherbrooke and Department of Medicine, Université de Sherbrooke, Sherbrooke, QC, Canada
- Division of Endocrinology, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Benoit Denhez
- Research Center of CHU de Sherbrooke and Department of Medicine, Université de Sherbrooke, Sherbrooke, QC, Canada
- Division of Endocrinology, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Andréanne Guay
- Research Center of CHU de Sherbrooke and Department of Medicine, Université de Sherbrooke, Sherbrooke, QC, Canada
- Division of Endocrinology, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Nicolas Gévry
- Department of Biology, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Anne Marie Côté
- Research Center of CHU de Sherbrooke and Department of Medicine, Université de Sherbrooke, Sherbrooke, QC, Canada
- Department of Nephrology, Université de Sherbrooke, Sherbrooke, QC, Canada
| | - Pedro Geraldes
- Research Center of CHU de Sherbrooke and Department of Medicine, Université de Sherbrooke, Sherbrooke, QC, Canada
- Division of Endocrinology, Université de Sherbrooke, Sherbrooke, QC, Canada
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173
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Abstract
IRS proteins are cellular adaptor molecules that mediate many of the key metabolic actions of insulin. When tyrosine is phosphorylated by the activated insulin receptor, IRS proteins recruit downstream effectors, such as phosphoinositide 3-kinase and mitogen-activated protein kinase, in order to elicit cellular responses such as glucose uptake, lipid metabolism and cell proliferation. There are two main IRS proteins in humans (IRS1 and IRS2), both of which are widely expressed. Given their central role in the insulin signalling pathway, it is not surprising that male mice lacking Irs1 or Irs2 present with elevated blood glucose or type 2 diabetes, respectively. For reasons yet to be identified, female Irs2 (-/-) mice do not develop type 2 diabetes. A number of organs are affected by complications of diabetes; macrovascular complications include stroke and coronary artery disease, while nephropathy, neuropathy and retinopathy fall into the category of microvascular complications. Given the serious consequences of these complications on patient morbidity and mortality, it is essential to identify the molecular pathogenesis underlying diabetic complications, with a view to improving therapeutic intervention and patient outcomes. A number of recently published papers have converged on the hypothesis that the loss of insulin signalling and IRS proteins is instrumental to the development and/or progression of diabetic complications. This review will summarise some highlights from the published work in which this hypothesis is discussed.
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Affiliation(s)
- Deborah P Lavin
- Centre for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast, BT9 7BL, Northern Ireland, UK
| | - Morris F White
- Division of Endocrinology, Children's Hospital Boston, Harvard Medical School, Boston, MA, USA
| | - Derek P Brazil
- Centre for Experimental Medicine, School of Medicine, Dentistry and Biomedical Sciences, Queen's University Belfast, 97 Lisburn Road, Belfast, BT9 7BL, Northern Ireland, UK.
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174
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Gnudi L, Coward RJM, Long DA. Diabetic Nephropathy: Perspective on Novel Molecular Mechanisms. Trends Endocrinol Metab 2016; 27:820-830. [PMID: 27470431 DOI: 10.1016/j.tem.2016.07.002] [Citation(s) in RCA: 219] [Impact Index Per Article: 27.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/15/2016] [Revised: 07/04/2016] [Accepted: 07/07/2016] [Indexed: 02/07/2023]
Abstract
Diabetes mellitus (DM) is the major cause of end-stage renal disease (ESRD) globally, and novel treatments are urgently needed. Current therapeutic approaches for diabetic nephropathy (DN) are focussing on blood pressure control with inhibitors of the renin-angiotensin-aldosterone system, on glycaemic and lipid control, and life-style changes. In this review, we highlight new molecular insights aiding our understanding of the initiation and progression of DN, including glomerular insulin resistance, dysregulation of cellular substrate utilisation, podocyte-endothelial communication, and inhibition of tubular sodium coupled glucose reabsorption. We believe that these mechanisms offer new therapeutic targets that can be exploited to develop important renoprotective treatments for DN over the next decade.
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Affiliation(s)
- Luigi Gnudi
- Cardiovascular Division, King's College London, London, SE1 9NH, UK.
| | - Richard J M Coward
- Academic Renal Unit, Dorothy Hodgkin Building, University of Bristol, Whitson Street, Bristol BS1 3NY, UK
| | - David A Long
- Developmental Biology and Cancer Programme, Institute of Child Health, University College London, London, WC1N 1EH, UK.
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175
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Ma R, Chaudhari S, Li W. Canonical Transient Receptor Potential 6 Channel: A New Target of Reactive Oxygen Species in Renal Physiology and Pathology. Antioxid Redox Signal 2016; 25:732-748. [PMID: 26937558 PMCID: PMC5079416 DOI: 10.1089/ars.2016.6661] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/02/2016] [Accepted: 02/06/2016] [Indexed: 02/07/2023]
Abstract
SIGNIFICANCE Regulation of Ca2+ signaling cascade by reactive oxygen species (ROS) is becoming increasingly evident and this regulation represents a key mechanism for control of many fundamental cellular functions. Canonical transient receptor potential (TRPC) 6, a member of Ca2+-conductive channel in the TRPC family, is widely expressed in kidney cells, including glomerular mesangial cells, podocytes, tubular epithelial cells, and vascular myocytes in renal microvasculature. Both overproduction of ROS and dysfunction of TRPC6 channel are involved in renal injury in animal models and human subjects. Although regulation of TRPC channel function by ROS has been well described in other tissues and cell types, such as vascular smooth muscle, this important cell regulatory mechanism has not been fully reviewed in kidney cells. Recent Advances: Accumulating evidence has shown that TRPC6 is a redox-sensitive channel, and modulation of TRPC6 Ca2+ signaling by altering TRPC6 protein expression or TRPC6 channel activity in kidney cells is a downstream mechanism by which ROS induce renal damage. CRITICAL ISSUES This review highlights how recent studies analyzing function and expression of TRPC6 channels in the kidney and their response to ROS improve our mechanistic understanding of oxidative stress-related kidney diseases. FUTURE DIRECTIONS Although it is evident that ROS regulate TRPC6-mediated Ca2+ signaling in several types of kidney cells, further study is needed to identify the underlying molecular mechanism. We hope that the newly identified ROS/TRPC6 pathway will pave the way to new, promising therapeutic strategies to target kidney diseases such as diabetic nephropathy. Antioxid. Redox Signal. 25, 732-748.
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Affiliation(s)
- Rong Ma
- Institute for Cardiovascular and Metabolic Diseases, University of North Texas Health Science Center, Fort Worth, Texas
| | - Sarika Chaudhari
- Institute for Cardiovascular and Metabolic Diseases, University of North Texas Health Science Center, Fort Worth, Texas
| | - Weizu Li
- Department of Pharmacology, Anhui Medical University, Hefei, People's Republic of China
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176
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Warmke N, Griffin KJ, Cubbon RM. Pericytes in diabetes-associated vascular disease. J Diabetes Complications 2016; 30:1643-1650. [PMID: 27592245 DOI: 10.1016/j.jdiacomp.2016.08.005] [Citation(s) in RCA: 50] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Revised: 08/01/2016] [Accepted: 08/08/2016] [Indexed: 12/21/2022]
Abstract
Pericytes are mural cells that support and stabilise the microvasculature, and are present in all vascular beds. Pericyte-endothelial cell crosstalk is essential in both remodelling and quiescent vasculature, and this complex interaction is often disrupted in disease states. Pericyte loss is believed to be an early hallmark of diabetes-associated microvascular disease, including retinopathy and nephropathy. Here we review the current literature defining pericyte biology in the context of diabetes-associated vascular disease, with a particular focus on whether pericytes contribute actively to disease progression. We also speculate regarding the role of pericytes in the recovery from macrovascular complications, such as critical limb ischaemia. It becomes clear that dysfunctional pericytes are likely to actively induce disease progression by causing vasoconstriction and basement membrane thickening, resulting in tissue ischaemia. Moreover, their altered interactions with endothelial cells are likely to cause abnormal and inadequate neovascularisation in diverse vascular beds. Further research is needed to identify mechanisms by which pericyte function is altered by diabetes, with a view to developing therapeutic approaches that normalise vascular function and remodelling.
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Affiliation(s)
- Nele Warmke
- Leeds Institute of Cardiovascular and Metabolic Medicine, LIGHT laboratories, The University of Leeds, Clarendon Way, Leeds, LS2 9JT, United Kingdom
| | - Kathryn J Griffin
- Leeds Institute of Cardiovascular and Metabolic Medicine, LIGHT laboratories, The University of Leeds, Clarendon Way, Leeds, LS2 9JT, United Kingdom
| | - Richard M Cubbon
- Leeds Institute of Cardiovascular and Metabolic Medicine, LIGHT laboratories, The University of Leeds, Clarendon Way, Leeds, LS2 9JT, United Kingdom.
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177
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Li SY, Susztak K. The long noncoding RNA Tug1 connects metabolic changes with kidney disease in podocytes. J Clin Invest 2016; 126:4072-4075. [PMID: 27760046 DOI: 10.1172/jci90828] [Citation(s) in RCA: 55] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022] Open
Abstract
An increasing amount of evidence suggests that metabolic alterations play a key role in chronic kidney disease (CKD) pathogenesis. In this issue of the JCI, Long et al. report that the long noncoding RNA (lncRNA) taurine-upregulated 1 (Tug1) contributes to CKD development. The authors show that Tug1 regulates mitochondrial function in podocytes by epigenetic targeting of expression of the transcription factor PPARγ coactivator 1α (PGC-1α, encoded by Ppargc1a). Transgenic overexpression of Tug1 specifically in podocytes ameliorated diabetes-induced CKD in mice. Together, these results highlight an important connection between lncRNA-mediated metabolic alterations in podocytes and kidney disease development.
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178
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Abstract
Insulin resistance is a systemic disorder that affects many organs and insulin-regulated pathways. The disorder is characterized by a reduced action of insulin despite increased insulin concentrations (hyperinsulinaemia). The effects of insulin on the kidney and vasculature differ in part from the effects on classical insulin target organs. Insulin causes vasodilation by enhancing endothelial nitric oxide production through activation of the phosphatidylinositol 3-kinase pathway. In insulin-resistant states, this pathway is impaired and the mitogen-activated protein kinase pathway stimulates vasoconstriction. The action of insulin on perivascular fat tissue and the subsequent effects on the vascular wall are not fully understood, but the hepatokine fetuin-A, which is released by fatty liver, might promote the proinflammatory effects of perivascular fat. The strong association of salt-sensitive arterial hypertension with insulin resistance indicates an involvement of the kidney in the insulin resistance syndrome. The insulin receptor is expressed on renal tubular cells and podocytes and insulin signalling has important roles in podocyte viability and tubular function. Renal sodium transport is preserved in insulin resistance and contributes to the salt-sensitivity of blood pressure in hyperinsulinaemia. Therapeutically, renal and vascular insulin resistance can be improved by an integrated holistic approach aimed at restoring overall insulin sensitivity and improving insulin signalling.
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179
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Liljedahl L, Pedersen MH, Norlin J, McGuire JN, James P. N-glycosylation proteome enrichment analysis in kidney reveals differences between diabetic mouse models. Clin Proteomics 2016; 13:22. [PMID: 27757071 PMCID: PMC5065702 DOI: 10.1186/s12014-016-9123-z] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2016] [Accepted: 08/23/2016] [Indexed: 11/26/2022] Open
Abstract
Background Diabetic nephropathy (DN) is a late complication in both type 1 diabetes mellitus (T1DM) and T2DM. Already at an early stage of DN morphological changes occur at the cell surface and in the extracellular matrix where the majority of the proteins carry N-linked glycosylations. These glycosylated proteins are highly important in cell adhesion and cell–matrix processes but not much is known about how they change in DN or whether the distinct etiology of T1DM and T2DM could have an effect on their abundances. Method We enriched for the N-glycosylated kidney proteome in db/db mice dosed with insulin or vehicle, in streptozotocin-induced (STZ) diabetic mice and healthy control mice dosed with vehicle. Glycopeptides were analyzed with label-free shotgun mass spectrometry and differential protein abundances identified in both mouse models were compared using multivariate analyses. Results The majority of the N-glycosylated proteins were similarly regulated in both mouse models. However, distinct differences between the two mouse models were for example seen for integrin-β1, a protein expressed mainly in the glomeruli which abundance was increased in the STZ diabetic mice while decreased in the db/db mice and for the sodium/glucose cotransporter-1, mainly expressed in the proximal tubules which abundance was increased in the db/db mice but decreased in the STZ diabetic mice. Insulin had an effect on the level of both glomerular and tubular proteins in the db/db mice. It decreased the abundance of G-protein coupled receptor-116 and of tyrosine-protein phosphatase non-receptor type substrate-1 away from the level in the healthy control mice. Conclusions Our finding of differences in the N-glycosylation protein profiles in the db/db and STZ mouse models suggest that the etiology of DN could give rise to variations in the cell adhesion and cell–matrix composition in T1DM and T2DM. Thus, N-glycosylated protein differences could be a clue to dissimilarities in T1DM and T2DM at later stages of DN. Furthermore, we observed insulin specific regulation of N-glycosylated proteins both in the direction of and away from the abundances in healthy control mice. Electronic supplementary material The online version of this article (doi:10.1186/s12014-016-9123-z) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Leena Liljedahl
- Department of Immunotechnology, Lund University, House 406, Medicon Village, 221 83 Lund, Sweden
| | | | - Jenny Norlin
- Novo Nordisk A/S, Novo Nordisk Park, 2760 Måløv, Denmark
| | | | - Peter James
- Department of Immunotechnology, Lund University, House 406, Medicon Village, 221 83 Lund, Sweden
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180
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Nair M, le Roux CW, Docherty NG. Mechanisms underpinning remission of albuminuria following bariatric surgery. Curr Opin Endocrinol Diabetes Obes 2016; 23:366-72. [PMID: 27584009 DOI: 10.1097/med.0000000000000279] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
PURPOSE OF REVIEW Albuminuria is a biomarker of renal injury commonly used to monitor progression of diabetic kidney disease. The appearance of excess albumin in the urine reflects alterations in the structure and permeability of the glomerular filtration barrier. The present article summarizes the clinical evidence base for remission of albuminuria after bariatric surgery. It furthermore focuses on how beneficial impacts on glomerular podocyte structure and function may explain this phenomenon. RECENT FINDINGS A coherent clinical evidence base is emerging demonstrating remission of albuminuria following bariatric surgery in patients with obesity and diabetes. The impaired metabolic milieu in diabetic kidney disease drives podocyte dedifferentiation and death through glucotoxic, lipotoxic proinflammatory, and pressure-related stress. Improvements in these parameters after surgery correlate with improvements in albuminuria and preclinical studies provide mechanistic data that support the existence of cause-effect relationship. SUMMARY The benefits of bariatric surgery extend beyond weight loss in diabetes to encompass beneficial effects on diabetic renal injury. Attenuation of the toxic metabolic milieu that the podocyte is exposed to postbariatric surgery suggests that the restitution of podocyte health is a key cellular event underpinning remission of albuminuria.
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Affiliation(s)
- Meera Nair
- aDiabetes Complications Research Centre, Conway Institute, School of Medicine and Medical Sciences, University College Dublin, Dublin, IrelandbDepartment of Gastrosurgical Research and Education, Institute of Clinical Sciences, Sahlgrenska Academy, University of Gothenburg, Gothenburg, SwedencInvestigative Science, Imperial College London, London, UK
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181
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Piwkowska A. Role of Protein Kinase G and Reactive Oxygen Species in the Regulation of Podocyte Function in Health and Disease. J Cell Physiol 2016; 232:691-697. [PMID: 27662602 DOI: 10.1002/jcp.25613] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/24/2016] [Accepted: 09/22/2016] [Indexed: 11/09/2022]
Abstract
Podocytes and their foot processes form an important cellular layer of the glomerular barrier involved in the regulation of glomerular permeability. Disturbing the function of podocytes plays a central role in the development of proteinuria in diabetic nephropathy. Retraction of the podocyte foot processes that form slit diaphragms is a common feature of proteinuria; although, the correlation between these events in not well understood. Notably, it is unclear whether podocyte foot processes are able to regulate slit diaphragm permeability and glomerular ultrafiltration. The occurrence of reactive oxygen species generation, insulin resistance, and hyperglycemia characterizes early stages of type 2 diabetes. Protein kinase G type I alpha (PKGIα) is an intracellular target for vasorelaxant factors. It is activated in both cGMP-dependent and cGMP-independent manners. Recently, we demonstrated a relationship between oxidative stress, PKGIα activation, actin reorganization, and changes in the permeability of the filtration barrier. This review discusses how redox imbalance affects both the activity of PKGIα and PKGI-dependent signaling pathways in podocytes. J. Cell. Physiol. 232: 691-697, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Agnieszka Piwkowska
- Mossakowski Medical Research Centre Polish Academy of Sciences, Laboratory of Molecular and Cellular Nephrology, Gdańsk, Poland
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182
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The role of mechanistic target of rapamycin in maintenance of glomerular epithelial cells. Curr Opin Nephrol Hypertens 2016; 25:28-34. [PMID: 26625863 DOI: 10.1097/mnh.0000000000000181] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
PURPOSE OF REVIEW Recent studies have emerged to reveal the pivotal roles of mechanistic target of rapamycin (mTOR) signaling not only in the maintenance of the physiological functions of renal cells but also in the pathogenesis of renal cell dysfunctions and kidney diseases. We introduce the current understanding of mTOR signaling, and its crucial roles in glomerular epithelial cell biology and the pathophysiology related to kidney diseases. RECENT FINDINGS mTOR, a Ser/Thr kinase, forms two distinct functional complexes, mTORC1 and mTORC2. Recent studies revealed that physiologic levels of mTORC1 and mTORC2 activity play key roles in maintaining podocyte and glomerular functions. However, aberrant activation of mTORC1 or loss of mTORC2 activity in podocytes may underlie the pathogenesis of glomerular disorders, including diabetic kidney disease. SUMMARY An effective treatment for mTORC1-associated podocyte and glomerular dysfunction may require the attenuation of mTORC1 activity in the setting of both an intact mTORC2 pathway and normal basal mTORC1 activity in order to preserve physiologic podocyte functions.
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183
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Xin W, Li Z, Xu Y, Yu Y, Zhou Q, Chen L, Wan Q. Autophagy protects human podocytes from high glucose-induced injury by preventing insulin resistance. Metabolism 2016; 65:1307-15. [PMID: 27506738 DOI: 10.1016/j.metabol.2016.05.015] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/19/2015] [Revised: 05/05/2016] [Accepted: 05/24/2016] [Indexed: 12/14/2022]
Abstract
OBJECTIVE Insulin resistance is correlated with the progress of albuminuria in diabetic patients, and podocytes are crucial for maintaining the normal function of the glomerular filtration barrier. In the present study, we aimed to investigate the high glucose-induced insulin resistance and cell injury in human podocytes and the putative role of autophagy in this process. METHODS Human podocytes were cultured in high glucose-supplemented medium and low glucose and high osmotic conditions were used for the controls. Autophagy in the podocytes was regulated using rapamycin or 3-methyladenine stimulation. Next, autophagy markers including LC3B, Beclin-1, and p62 were investigated using western blot and qPCR, and the insulin responsiveness was analyzed based on glucose uptake and by using the phosphorylation of the insulin receptor with Nephrin as a podocyte injury marker. RESULTS The basal autophagy level decreased under the high glucose conditions, which was accompanied by a decrease in the glucose uptake and phosphorylation of the insulin receptor in the human podocytes. More interestingly, the glucose uptake and the phosphorylation of the insulin receptor were decreased by 3-MA stimulation and increased by rapamycin, illustrating that the responsiveness of insulin was regulated by autophagy. The activation of autophagy by rapamycin also ameliorated cell injury in the human podocytes. CONCLUSIONS The presence or activation of autophagy was found to play a protective role in human podocytes against high glucose-induced insulin resistance and cell injury, which indicates a novel cellular mechanism and provides a potential therapeutic target for diabetic nephropathy (DN).
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Affiliation(s)
- Wei Xin
- Department of Central Laboratory, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, 250021, China
| | - Zhaoping Li
- Institute of Nutrition and Food Hygiene, School of Public Health, Shandong University, Jinan, 250012, China
| | - Ying Xu
- Department of Nephrology, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, 250021, China
| | - Yue Yu
- Institute of Nutrition and Food Hygiene, School of Public Health, Shandong University, Jinan, 250012, China
| | - Qi Zhou
- School of Medicine, Shandong University, Jinan, 250012, China
| | - Liyong Chen
- Department of Nutrition, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, 250021, China.
| | - Qiang Wan
- Department of Nephrology, Qianfoshan Hospital Affiliated to Shandong University, Jinan, 250014, China.
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184
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Marshall CB. Rethinking glomerular basement membrane thickening in diabetic nephropathy: adaptive or pathogenic? Am J Physiol Renal Physiol 2016; 311:F831-F843. [PMID: 27582102 DOI: 10.1152/ajprenal.00313.2016] [Citation(s) in RCA: 72] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 08/21/2016] [Indexed: 12/12/2022] Open
Abstract
Diabetic nephropathy (DN) is the leading cause of chronic kidney disease in the United States and is a major cause of cardiovascular disease and death. DN develops insidiously over a span of years before clinical manifestations, including microalbuminuria and declining glomerular filtration rate (GFR), are evident. During the clinically silent period, structural lesions develop, including glomerular basement membrane (GBM) thickening, mesangial expansion, and glomerulosclerosis. Once microalbuminuria is clinically apparent, structural lesions are often considerably advanced, and GFR decline may then proceed rapidly toward end-stage kidney disease. Given the current lack of sensitive biomarkers for detecting early DN, a shift in focus toward examining the cellular and molecular basis for the earliest structural change in DN, i.e., GBM thickening, may be warranted. Observed within one to two years following the onset of diabetes, GBM thickening precedes clinically evident albuminuria. In the mature glomerulus, the podocyte is likely key in modifying the GBM, synthesizing and assembling matrix components, both in physiological and pathological states. Podocytes also secrete matrix metalloproteinases, crucial mediators in extracellular matrix turnover. Studies have shown that the critical podocyte-GBM interface is disrupted in the diabetic milieu. Just as healthy podocytes are essential for maintaining the normal GBM structure and function, injured podocytes likely have a fundamental role in upsetting the balance between the GBM's synthetic and degradative pathways. This article will explore the biological significance of GBM thickening in DN by reviewing what is known about the GBM's formation, its maintenance during health, and its disruption in DN.
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Affiliation(s)
- Caroline B Marshall
- Division of Nephrology, Department of Medicine, University of Alabama at Birmingham, Birmingham, Alabama; and Department of Veterans Affairs Medical Center, Birmingham, Alabama
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185
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McPherson KC, Taylor L, Johnson AC, Didion SP, Geurts AM, Garrett MR, Williams JM. Early development of podocyte injury independently of hyperglycemia and elevations in arterial pressure in nondiabetic obese Dahl SS leptin receptor mutant rats. Am J Physiol Renal Physiol 2016; 311:F793-F804. [PMID: 27465994 DOI: 10.1152/ajprenal.00590.2015] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2015] [Accepted: 07/25/2016] [Indexed: 01/05/2023] Open
Abstract
The current study examined the effect of obesity on the development of renal injury within the genetic background of the Dahl salt-sensitive rat with a dysfunctional leptin receptor derived from zinc-finger nucleases (SSLepRmutant strain). At 6 wk of age, body weight was 35% higher in the SSLepRmutant strain compared with SSWT rats and remained elevated throughout the entire study. The SSLepRmutant strain exhibited impaired glucose tolerance and increased plasma insulin levels at 6 wk of age, suggesting insulin resistance while SSWT rats did not. However, blood glucose levels were normal throughout the course of the study. Systolic arterial pressure (SAP) was similar between the two strains from 6 to 10 wk of age. However, by 18 wk of age, the development of hypertension was more severe in the SSLepRmutant strain compared with SSWT rats (201 ± 10 vs. 155 ± 3 mmHg, respectively). Interestingly, proteinuria was substantially higher at 6 wk of age in the SSLepRmutant strain vs. SSWT rats (241 ± 27 vs. 24 ± 2 mg/day, respectively) and remained elevated until the end of the study. The kidneys from the SSLepRmutant strain displayed significant glomerular injury, including podocyte foot process effacement and lipid droplets compared with SSWT rats as early as 6 wk of age. By 18 wk of age, plasma creatinine levels were twofold higher in the SSLepRmutant strain vs. SSWT rats, suggesting the presence of chronic kidney disease (CKD). Overall, these results indicate that the SSLepRmutant strain develops podocyte injury and proteinuria independently of hyperglycemia and elevated arterial pressure that later progresses to CKD.
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Affiliation(s)
- Kasi C McPherson
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi; and
| | - Lateia Taylor
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi; and
| | - Ashley C Johnson
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi; and
| | - Sean P Didion
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi; and
| | - Aron M Geurts
- Human Molecular Genetics Center, Medical College of Wisconsin, Milwaukee, Wisconsin
| | - Michael R Garrett
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi; and
| | - Jan M Williams
- Department of Pharmacology and Toxicology, University of Mississippi Medical Center, Jackson, Mississippi; and
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186
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Katsoulieris EN, Drossopoulou GI, Kotsopoulou ES, Vlahakos DV, Lianos EA, Tsilibary EC. High Glucose Impairs Insulin Signaling in the Glomerulus: An In Vitro and Ex Vivo Approach. PLoS One 2016; 11:e0158873. [PMID: 27434075 PMCID: PMC4951020 DOI: 10.1371/journal.pone.0158873] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/25/2016] [Accepted: 06/23/2016] [Indexed: 01/14/2023] Open
Abstract
Objective Chronic hyperglycaemia, as seen in type II diabetes, results in both morphological and functional impairments of podocytes in the kidney. We investigated the effects of high glucose (HG) on the insulin signaling pathway, focusing on cell survival and apoptotic markers, in immortalized human glomerular cells (HGEC; podocytes) and isolated glomeruli from healthy rats. Methods and Findings HGEC and isolated glomeruli were cultured for various time intervals under HG concentrations in the presence or absence of insulin. Our findings indicated that exposure of HGEC to HG led to downregulation of all insulin signaling markers tested (IR, p-IR, IRS-1, p-Akt, p-Fox01,03), as well as to increased sensitivity to apoptosis (as seen by increased PARP cleavage, Casp3 activation and DNA fragmentation). Short insulin pulse caused upregulation of insulin signaling markers (IR, p-IR, p-Akt, p-Fox01,03) in a greater extent in normoglycaemic cells compared to hyperglycaemic cells and for the case of p-Akt, in a PI3K-dependent manner. IRS-1 phosphorylation of HG-treated podocytes was negatively regulated, favoring serine versus tyrosine residues. Prolonged insulin treatment caused a significant decrease of IR levels, while alterations in glucose concentrations for various time intervals demonstrated changes of IR, p-IR and p-Akt levels, suggesting that the IR signaling pathway is regulated by glucose levels. Finally, HG exerted similar effects in isolated glomeruli. Conclusions These results suggest that HG compromises the insulin signaling pathway in the glomerulus, promoting a proapoptotic environment, with a possible critical step for this malfunction lying at the level of IRS-1 phosphorylation; thus we herein demonstrate glomerular insulin signaling as another target for investigation for the prevention and/ or treatment of diabetic nephropathy.
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Affiliation(s)
- Elias N. Katsoulieris
- Institute of Biosciences and Applications, National Center for Scientific Research ‘Demokritos’, Athens, Greece
| | - Garyfalia I. Drossopoulou
- Institute of Biosciences and Applications, National Center for Scientific Research ‘Demokritos’, Athens, Greece
- * E-mail: (GID); (ECT)
| | - Eleni S. Kotsopoulou
- Institute of Biosciences and Applications, National Center for Scientific Research ‘Demokritos’, Athens, Greece
| | - Dimitrios V. Vlahakos
- 2nd Department of Propaedeutic Medicine, Attikon University Hospital, Athens, Greece
| | - Elias A. Lianos
- Department of Pathology, National and Kapodistrian University of Athens, Medical School, Athens, Greece
| | - Effie C. Tsilibary
- Institute of Biosciences and Applications, National Center for Scientific Research ‘Demokritos’, Athens, Greece
- * E-mail: (GID); (ECT)
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187
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Obesity-related glomerulopathy: clinical and pathologic characteristics and pathogenesis. Nat Rev Nephrol 2016; 12:453-71. [PMID: 27263398 DOI: 10.1038/nrneph.2016.75] [Citation(s) in RCA: 432] [Impact Index Per Article: 54.0] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The prevalence of obesity-related glomerulopathy is increasing in parallel with the worldwide obesity epidemic. Glomerular hypertrophy and adaptive focal segmental glomerulosclerosis define the condition pathologically. The glomerulus enlarges in response to obesity-induced increases in glomerular filtration rate, renal plasma flow, filtration fraction and tubular sodium reabsorption. Normal insulin/phosphatidylinositol 3-kinase/Akt and mTOR signalling are critical for podocyte hypertrophy and adaptation. Adipokines and ectopic lipid accumulation in the kidney promote insulin resistance of podocytes and maladaptive responses to cope with the mechanical forces of renal hyperfiltration. Although most patients have stable or slowly progressive proteinuria, up to one-third develop progressive renal failure and end-stage renal disease. Renin-angiotensin-aldosterone blockade is effective in the short-term but weight loss by hypocaloric diet or bariatric surgery has induced more consistent and dramatic antiproteinuric effects and reversal of hyperfiltration. Altered fatty acid and cholesterol metabolism are increasingly recognized as key mediators of renal lipid accumulation, inflammation, oxidative stress and fibrosis. Newer therapies directed to lipid metabolism, including SREBP antagonists, PPARα agonists, FXR and TGR5 agonists, and LXR agonists, hold therapeutic promise.
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188
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Zhuang A, Forbes JM. Diabetic kidney disease: a role for advanced glycation end-product receptor 1 (AGE-R1)? Glycoconj J 2016; 33:645-52. [PMID: 27270766 DOI: 10.1007/s10719-016-9693-z] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2016] [Revised: 05/26/2016] [Accepted: 05/27/2016] [Indexed: 01/07/2023]
Abstract
Diabetic patients are postulated to be in a perpetual state of oxidative stress and inflammation at sites where chronic complications occur. The accumulation of AGEs derived from both endogenous and exogenous sources (such as the diet) have been implicated in the development and progression of diabetic complications, particularly nephropathy. There has been some interest in investigating the potential for reducing the AGE burden in chronic disease, through the action of AGE "clearance" receptors, such as the advanced glycation end-product receptor 1 (AGE-R1). Reducing the burden of AGEs has been linked to attenuation of inflammation, slower progression of diabetic complications (in particular vascular and renal complications) and has been shown to extend lifespan. To date, however, there have been no direct investigations into whether AGE-R1 has any role in modulating normal kidney function, or specifically during the development and progression of diabetes. This mini-review will focus on the recent advances in knowledge around the mechanistic function of AGE-R1 and the implications of this for the pathogenesis of diabetic kidney disease.
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Affiliation(s)
- Aowen Zhuang
- Glycation and Diabetes Group, Mater Research Institute, Translational Research Institute, The University of Queensland, South Brisbane, Queensland, Australia
| | - Josephine M Forbes
- Glycation and Diabetes Group, Mater Research Institute, Translational Research Institute, The University of Queensland, South Brisbane, Queensland, Australia. .,Mater Clinical School, The University of Queensland, South Brisbane, Queensland, Australia.
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189
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Cao AL, Wang L, Chen X, Wang YM, Guo HJ, Chu S, Liu C, Zhang XM, Peng W. Ursodeoxycholic acid and 4-phenylbutyrate prevent endoplasmic reticulum stress-induced podocyte apoptosis in diabetic nephropathy. J Transl Med 2016; 96:610-22. [PMID: 26999661 DOI: 10.1038/labinvest.2016.44] [Citation(s) in RCA: 85] [Impact Index Per Article: 10.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2015] [Revised: 02/13/2016] [Accepted: 02/16/2016] [Indexed: 02/07/2023] Open
Abstract
Endoplasmic reticulum (ER) stress, resulting from the accumulation of misfolded and/or unfolded proteins in ER membranes, is involved in the pathogenesis of diabetic nephropathy (DN). The aim of this study was to investigate the role of ER stress inhibitors ursodeoxycholic acid (UDCA) and 4-phenylbutyrate (4-PBA) in the treatment of DN in db/db mice. Findings have revealed that diabetic db/db mice were more hyperglycemic than their non-diabetic controls, and exhibited a marked increase in body weight, water intake, urine volume, fasting plasma glucose, systolic blood pressure, glucose and insulin tolerance. UDCA (40 mg/kg/day) or 4-PBA (100 mg/kg/day) treatment for 12 weeks resulted in an improvement in these biochemical and physical parameters. Moreover, UDCA or 4-PBA intervention markedly decreased urinary albuminuria and attenuated mesangial expansion in diabetic db/db mice, compared with db/db mice treated with vehicle. These beneficial effects of UDCA or 4-PBA on DN were associated with the inhibition of ER stress, as evidenced by the decreased expression of BiP, phospho-IRE1α, phospho-eIF2α, CHOP, ATF-6 and spliced X-box binding protein-1 in vitro and in vivo. UDCA or 4-PBA prevented hyperglycemia-induced or high glucose (HG)-induced apoptosis in podocytes in vivo and in vitro via the inhibition of caspase-3 and caspase-12 activation. Autophagy deficiency was also seen in glomeruli in diabetic mice and HG-incubated podocytes, exhibiting decreased expression of LC3B and Beclin-1, which could be restored by UDCA or 4-PBA treatment. Taken together, our results have revealed an important role of ER stress in the development of DN, and UDCA or 4-PBA treatment may be a potential novel therapeutic approach for the treatment of DN.
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Affiliation(s)
- Ai-Li Cao
- Laboratory of Renal Disease, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Li Wang
- Laboratory of Renal Disease, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Xia Chen
- Department of Nephrology, Laboratory of Renal Disease, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Yun-Man Wang
- Department of Nephrology, Laboratory of Renal Disease, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Heng-Jiang Guo
- Laboratory of Renal Disease, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Shuang Chu
- Laboratory of Renal Disease, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Cheng Liu
- Laboratory of Renal Disease, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
| | - Xue-Mei Zhang
- Department of Pharmacology, School of Pharmacy, Fudan University, Shanghai, China
| | - Wen Peng
- Department of Nephrology, Laboratory of Renal Disease, Putuo Hospital, Shanghai University of Traditional Chinese Medicine, Shanghai, China
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190
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Selective Insulin Resistance in the Kidney. BIOMED RESEARCH INTERNATIONAL 2016; 2016:5825170. [PMID: 27247938 PMCID: PMC4876201 DOI: 10.1155/2016/5825170] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/16/2016] [Revised: 04/04/2016] [Accepted: 04/07/2016] [Indexed: 12/12/2022]
Abstract
Insulin resistance has been characterized as attenuation of insulin sensitivity at target organs and tissues, such as muscle and fat tissues and the liver. The insulin signaling cascade is divided into major pathways such as the PI3K/Akt pathway and the MAPK/MEK pathway. In insulin resistance, however, these pathways are not equally impaired. For example, in the liver, inhibition of gluconeogenesis by the insulin receptor substrate (IRS) 2 pathway is impaired, while lipogenesis by the IRS1 pathway is preserved, thus causing hyperglycemia and hyperlipidemia. It has been recently suggested that selective impairment of insulin signaling cascades in insulin resistance also occurs in the kidney. In the renal proximal tubule, insulin signaling via IRS1 is inhibited, while insulin signaling via IRS2 is preserved. Insulin signaling via IRS2 continues to stimulate sodium reabsorption in the proximal tubule and causes sodium retention, edema, and hypertension. IRS1 signaling deficiency in the proximal tubule may impair IRS1-mediated inhibition of gluconeogenesis, which could induce hyperglycemia by preserving glucose production. In the glomerulus, the impairment of IRS1 signaling deteriorates the structure and function of podocyte and endothelial cells, possibly causing diabetic nephropathy. This paper mainly describes selective insulin resistance in the kidney, focusing on the proximal tubule.
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191
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Abstract
Diabetes is increasing in prevalence and is the leading cause of end-stage renal disease in the United States. Diabetic kidney disease is considered a proteinuric glomerular disease. Although the glomerulus is composed of various cell types, research suggests that podocytes are critical to overall glomerular health. Podocyte injury has been identified as a pivotal event resulting in proteinuric kidney disease, glomerulosclerosis, and loss of renal function. Thus, understanding the signaling mechanisms that trigger podocyte injury in diabetic kidney disease might allow for the development of targeted therapeutics to prevent or ameliorate progression to end-stage renal failure. This review focuses on the role of podocytes in diabetic kidney disease.
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Affiliation(s)
- Jamie S Lin
- Renal-Electrolyte and Hypertension Division, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Katalin Susztak
- Renal-Electrolyte and Hypertension Division, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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192
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Batchu SN, Majumder S, Bowskill BB, White KE, Advani SL, Brijmohan AS, Liu Y, Thai K, Azizi PM, Lee WL, Advani A. Prostaglandin I2 Receptor Agonism Preserves β-Cell Function and Attenuates Albuminuria Through Nephrin-Dependent Mechanisms. Diabetes 2016; 65:1398-409. [PMID: 26868296 DOI: 10.2337/db15-0783] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/08/2015] [Accepted: 02/01/2016] [Indexed: 11/13/2022]
Abstract
Discovery of common pathways that mediate both pancreatic β-cell function and end-organ function offers the opportunity to develop therapies that modulate glucose homeostasis and separately slow the development of diabetes complications. Here, we investigated the in vitro and in vivo effects of pharmacological agonism of the prostaglandin I2 (IP) receptor in pancreatic β-cells and in glomerular podocytes. The IP receptor agonist MRE-269 increased intracellular 3',5'-cyclic adenosine monophosphate (cAMP), augmented glucose-stimulated insulin secretion (GSIS), and increased viability in MIN6 β-cells. Its prodrug form, selexipag, augmented GSIS and preserved islet β-cell mass in diabetic mice. Determining that this preservation of β-cell function is mediated through cAMP/protein kinase A (PKA)/nephrin-dependent pathways, we found that PKA inhibition, nephrin knockdown, or targeted mutation of phosphorylated nephrin tyrosine residues 1176 and 1193 abrogated the actions of MRE-269 in MIN6 cells. Because nephrin is important to glomerular permselectivity, we next set out to determine whether IP receptor agonism similarly affects nephrin phosphorylation in podocytes. Expression of the IP receptor in podocytes was confirmed in cultured cells by immunoblotting and quantitative real-time PCR and in mouse kidneys by immunogold electron microscopy, and its agonism 1) increased cAMP, 2) activated PKA, 3) phosphorylated nephrin, and 4) attenuated albumin transcytosis. Finally, treatment of diabetic endothelial nitric oxide synthase knockout mice with selexipag augmented renal nephrin phosphorylation and attenuated albuminuria development independently of glucose change. Collectively, these observations describe a pharmacological strategy that posttranslationally modifies nephrin and the effects of this strategy in the pancreas and in the kidney.
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MESH Headings
- Acetamides/therapeutic use
- Acetates/pharmacology
- Animals
- Cell Line
- Cell Survival/drug effects
- Diabetes Mellitus, Experimental/complications
- Diabetes Mellitus, Experimental/drug therapy
- Diabetes Mellitus, Experimental/metabolism
- Diabetes Mellitus, Experimental/pathology
- Diabetic Nephropathies/metabolism
- Diabetic Nephropathies/pathology
- Diabetic Nephropathies/physiopathology
- Diabetic Nephropathies/prevention & control
- Humans
- Hypoglycemic Agents/pharmacology
- Hypoglycemic Agents/therapeutic use
- Insulin/agonists
- Insulin/metabolism
- Insulin Secretion
- Insulin-Secreting Cells/drug effects
- Insulin-Secreting Cells/metabolism
- Membrane Proteins/antagonists & inhibitors
- Membrane Proteins/genetics
- Membrane Proteins/metabolism
- Mice, Inbred C57BL
- Mice, Knockout
- Mutation
- Phosphorylation/drug effects
- Podocytes/drug effects
- Podocytes/metabolism
- Podocytes/pathology
- Podocytes/ultrastructure
- Prodrugs/therapeutic use
- Protein Processing, Post-Translational/drug effects
- Pyrazines/pharmacology
- Pyrazines/therapeutic use
- RNA Interference
- Receptors, Epoprostenol/agonists
- Receptors, Epoprostenol/genetics
- Receptors, Epoprostenol/metabolism
- Renal Insufficiency/complications
- Renal Insufficiency/metabolism
- Renal Insufficiency/pathology
- Renal Insufficiency/prevention & control
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Affiliation(s)
- Sri N Batchu
- Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, Ontario, Canada
| | - Syamantak Majumder
- Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, Ontario, Canada
| | - Bridgit B Bowskill
- Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, Ontario, Canada
| | - Kathryn E White
- Electron Microscopy Research Services, Newcastle University, Newcastle upon Tyne, U.K
| | - Suzanne L Advani
- Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, Ontario, Canada
| | - Angela S Brijmohan
- Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, Ontario, Canada
| | - Youan Liu
- Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, Ontario, Canada
| | - Kerri Thai
- Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, Ontario, Canada
| | - Paymon M Azizi
- Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, Ontario, Canada
| | - Warren L Lee
- Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, Ontario, Canada
| | - Andrew Advani
- Keenan Research Centre for Biomedical Science and Li Ka Shing Knowledge Institute of St. Michael's Hospital, Toronto, Ontario, Canada
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193
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Xu Y, Zhou Q, Xin W, Li Z, Chen L, Wan Q. Autophagy downregulation contributes to insulin resistance mediated injury in insulin receptor knockout podocytes in vitro. PeerJ 2016; 4:e1888. [PMID: 27077005 PMCID: PMC4830256 DOI: 10.7717/peerj.1888] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Accepted: 03/13/2016] [Indexed: 12/30/2022] Open
Abstract
It is unknown whether autophagy activity is altered in insulin resistant podocytes and whether autophagy could be a therapeutic target for diabetic nephropathy (DN). Here we used shRNA transfection to knockdown the insulin receptor (IR) gene in cultured human immortalized podocytes as an in vitro insulin resistant model. Autophagy related proteins LC3, Beclin, and p62 as well as nephrin, a podocyte injury marker, were assessed using western blot and immunofluorescence staining. Our results show that autophagy is suppressed when podocytes lose insulin sensitivity and that treatment of rapamycin, an mTOR specific inhibitor, could attenuate insulin resistance induced podocytes injury via autophagy activation. The present study deepens our understanding of the role of autophagy in the pathogenesis of DN.
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Affiliation(s)
- Ying Xu
- Department of Nephrology, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, Shandong, China
| | - Qi Zhou
- School of Medicine, Shandong University, Jinan, Shandong, China
| | - Wei Xin
- Central Lab, Shandong Provincial Hospital Affiliated to Shandong University, Jinan, Shandong, China
| | - Zhaoping Li
- School of Public Health, Shandong University, Jinan, Shandong, China
| | - Liyong Chen
- Department of Nutrition, Shandong Provincial Hospital Affiliated to Shandong Hospital, Jinan, Shandong, China
| | - Qiang Wan
- Department of Nephrology, Qianfoshan Hospital Affiliated to Shandong University, Jinan, Shandong, China
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194
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Bienaimé F, Canaud G, El Karoui K, Gallazzini M, Terzi F. Molecular pathways of chronic kidney disease progression. Nephrol Ther 2016; 12 Suppl 1:S35-8. [DOI: 10.1016/j.nephro.2016.02.009] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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195
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Yao Y, Wang J, Yoshida S, Nada S, Okada M, Inoki K. Role of Ragulator in the Regulation of Mechanistic Target of Rapamycin Signaling in Podocytes and Glomerular Function. J Am Soc Nephrol 2016; 27:3653-3665. [PMID: 27032892 DOI: 10.1681/asn.2015010032] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/08/2015] [Accepted: 02/17/2016] [Indexed: 02/03/2023] Open
Abstract
Aberrant activation of mechanistic target of rapamycin complex 1 (mTORC1) in glomerular podocytes leads to glomerular insufficiency and may contribute to the development of glomerular diseases, including diabetic nephropathy. Thus, an approach for preventing mTORC1 activation may allow circumvention of the onset and progression of mTORC1-dependent podocyte injury and glomerular diseases. mTORC1 activation requires inputs from both growth factors and nutrients that inactivate the tuberous sclerosis complex (TSC), a key suppressor of mTORC1, on the lysosome. Previous studies in mice revealed that the growth factor-phosphatidylinositol 3-kinase pathway and mTORC1 are essential for maintaining normal podocyte function, suggesting that direct inhibition of the phosphatidylinositol 3-kinase pathway or mTORC1 may not be an ideal approach to sustaining physiologic podocyte functions under certain disease conditions. Here, we report the role of the Ragulator complex, which recruits mTORC1 to lysosomes in response to nutrient availability in podocytes. Notably, podocytes lacking Ragulator maintain basal mTORC1 activity. Unlike podocyte-specific mTORC1-knockout mice, mice lacking functional Ragulator in podocytes did not show abnormalities in podocyte or glomerular function. However, aberrant mTORC1 activation induced by active Rheb in podocyte-specific TSC1-knockout (podo-TSC1 KO) mice did require Ragulator. Moreover, ablation of Ragulator in the podocytes of podo-TSC1 KO mice or streptozotocin-induced diabetic mice significantly blocked the development of pathologic renal phenotypes. These observations suggest that the blockade of mTORC1 recruitment to lysosomes may be a useful clinical approach to attenuate aberrant mTORC1 activation under certain disease conditions.
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Affiliation(s)
| | | | - Sei Yoshida
- Life Sciences Institute.,Department of Microbiology and Immunology
| | - Shigeyuki Nada
- Department of Oncogene Research, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Masato Okada
- Department of Oncogene Research, Research Institute for Microbial Diseases, Osaka University, Osaka, Japan
| | - Ken Inoki
- Life Sciences Institute, .,Department of Molecular and Integrative Physiology, and.,Department of Internal Medicine, Division of Nephrology, University of Michigan, Ann Arbor, Michigan; and
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196
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Korstanje R, Deutsch K, Bolanos-Palmieri P, Hanke N, Schroder P, Staggs L, Bräsen JH, Roberts ISD, Sheehan S, Savage H, Haller H, Schiffer M. Loss of Kynurenine 3-Mono-oxygenase Causes Proteinuria. J Am Soc Nephrol 2016; 27:3271-3277. [PMID: 27020856 DOI: 10.1681/asn.2015070835] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2015] [Accepted: 02/13/2016] [Indexed: 11/03/2022] Open
Abstract
Changes in metabolite levels of the kynurenine pathway have been observed in patients with CKD, suggesting involvement of this pathway in disease pathogenesis. Our recent genetic analysis in the mouse identified the kynurenine 3-mono-oxygenase (KMO) gene (Kmo) as a candidate gene associated with albuminuria. This study investigated this association in more detail. We compared KMO abundance in the glomeruli of mice and humans under normal and diabetic conditions, observing a decrease in glomerular KMO expression with diabetes. Knockdown of kmo expression in zebrafish and genetic deletion of Kmo in mice each led to a proteinuria phenotype. We observed pronounced podocyte foot process effacement on long stretches of the filtration barrier in the zebrafish knockdown model and mild podocyte foot process effacement in the mouse model, whereas all other structures within the kidney remained unremarkable. These data establish the candidacy of KMO as a causal factor for changes in the kidney leading to proteinuria and indicate a functional role for KMO and metabolites of the tryptophan pathway in podocytes.
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Affiliation(s)
- Ron Korstanje
- The Jackson Laboratory, Bar Harbor, Maine; .,Mount Desert Island Biological Laboratory, Bar Harbor, Maine
| | | | | | - Nils Hanke
- Division of Nephrology and Hypertension, and
| | - Patricia Schroder
- Mount Desert Island Biological Laboratory, Bar Harbor, Maine.,Division of Nephrology and Hypertension, and
| | - Lynne Staggs
- Mount Desert Island Biological Laboratory, Bar Harbor, Maine.,Division of Nephrology and Hypertension, and
| | - Jan H Bräsen
- Department of Pathology, Hannover Medical School, Hannover, Germany; and
| | - Ian S D Roberts
- Department of Cellular Pathology, John Radcliffe Hospital, Headley Way, Headington, Oxford, United Kingdom
| | | | | | - Hermann Haller
- Mount Desert Island Biological Laboratory, Bar Harbor, Maine.,Division of Nephrology and Hypertension, and
| | - Mario Schiffer
- Mount Desert Island Biological Laboratory, Bar Harbor, Maine; .,Division of Nephrology and Hypertension, and
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197
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Abstract
In the last few decades, rapid changes in lifestyle have led to an alarming increase in the prevalence of obesity and obesity-associated complications. Obese patients are at increased risk of developing hypertension, heart disease, insulin resistance, dyslipidemia, type 2 diabetes and kidney disease. The surplus of calories is normally stored as triglycerides in adipose tissue. However, excess lipids can also accumulate ectopically in other organs, including the kidney, contributing to their damage through toxic processes named lipotoxicity. The kidney is negatively affected by dyslipidemia, lipid accumulation and changes in circulating adipokines that bring about alterations in renal lipid metabolism and promote insulin resistance, generation of reactive oxygen species and endoplasmic reticulum stress, ultimately leading to alterations in the glomerular filtration barrier and renal failure. This review focuses on the pathogenic molecular mechanisms associated with renal lipotoxicity, and presents new insights about potential new therapeutic targets and biomarkers such as microRNAs and long non-coding RNAs, of relevance for the early detection of lipid-associated kidney disease.
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198
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Zheng T, Liu Y, Qin S, Liu H, Zhang X, Zhao H. Increased plasma dipeptidyl peptidase-4 activities are associated with high prevalence of diabetic nephropathy in Chinese patients with newly diagnosed type 2 diabetes: A cross-sectional study. Diab Vasc Dis Res 2016; 13:127-36. [PMID: 26821795 DOI: 10.1177/1479164115615356] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
OBJECTIVE To investigate the association between plasma Dipeptidyl peptidase-4 (DPP4) activities and diabetic nephropathy in type 2 diabetes. RESEARCH DESIGN AND METHODS A total of 1193 newly diagnosed type 2 diabetic subjects were studied. Plasma DPP4 activity, mannose 6-phosphate receptor, inflammatory markers and oxidative stress parameters were measured in all participants. Diabetic nephropathy was defined as the presence of albuminuria or an estimated glomerular filtration rate < 60 mL/min/1.73 m(2). RESULTS Participants in the highest quartile of DPP4 activity had higher HbA1c, homeostatic model assessment of insulin resistance, nitrotyrosine, 8-iso-PGF2a, interleukin-6, high-sensitivity C-reactive protein, mannose 6-phosphate receptor, urinary albumin-to-creatinine ratio and lower estimated glomerular filtration rate compared with participants in the lowest quartile (all p < 0.001). DPP4 activities were associated positively with HbA1c, homeostatic model assessment of insulin resistance, nitrotyrosine, 8-iso-PGF2a, interleukin-6, high-sensitivity C-reactive protein, mannose 6-phosphate receptor, urinary albumin-to-creatinine ratio and negatively with estimated glomerular filtration rate (all p < 0.001). In the highest DPP4 quartile, diabetic nephropathy risk was significantly higher (odds ratio: 3.77; 95% confidence interval: 2.34-6.07) than in the lowest quartile after adjustment for potential confounders. This association remained strong (2.85; 1.74-4.68) after further controlling for HbA1c, homeostatic model assessment of insulin resistance, nitrotyrosine and high-sensitivity C-reactive protein. CONCLUSION This study shows that increased DPP4 activities are strongly and independently associated with diabetic nephropathy in type 2 diabetes. The associations between DPP4 and diabetic nephropathy, although strong, do not imply causality. There are however plausible mechanisms which could explain such a link.
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Affiliation(s)
- Tianpeng Zheng
- Department of Endocrinology and Metabolism, Affiliated Hospital of Guilin Medical University, Guilin, P.R. China Center of Diabetic Systems Medicine, Guilin Medical University, Guilin, P.R. China
| | - Yihong Liu
- Diabetic Centre of Control and Prevention, The People's Liberation Army 520 Hospital, Mianyang, P.R. China
| | - Shenghua Qin
- Medical Examination Center, Affiliated Hospital of Guilin Medical University, Guilin, P.R. China
| | - Hongbo Liu
- Department of Laboratory Medicine, Affiliated Hospital of Guilin Medical University, Guilin, P.R. China
| | - Xiaoxi Zhang
- Center of Diabetic Systems Medicine, Guilin Medical University, Guilin, P.R. China
| | - Hailu Zhao
- Center of Diabetic Systems Medicine, Guilin Medical University, Guilin, P.R. China
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199
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Uehara S, Hayashi T, Kogawa Sato K, Kinuhata S, Shibata M, Oue K, Kambe H, Hashimoto K. Relationship Between Alcohol Drinking Pattern and Risk of Proteinuria: The Kansai Healthcare Study. J Epidemiol 2016; 26:464-70. [PMID: 26902169 PMCID: PMC5008966 DOI: 10.2188/jea.je20150158] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023] Open
Abstract
Background Moderate alcohol consumption has been reported to be associated with a decreased risk of cardiometabolic diseases. Whether drinking pattern is associated with the risk of proteinuria is unknown. Methods Study subjects were 9154 non-diabetic Japanese men aged 40–55 years, with an estimated glomerular filtration rate ≥60 mL/min/1.73 m2, no proteinuria, and no use of antihypertensive medications at entry. Data on alcohol consumption were obtained by questionnaire. We defined “consecutive proteinuria” as proteinuria detected twice consecutively as 1+ or higher on urine dipstick at annual examinations. Results During the 81 147 person-years follow-up period, 385 subjects developed consecutive proteinuria. For subjects who reported drinking 4–7 days per week, alcohol consumption of 0.1–23.0 g ethanol/drinking day was significantly associated with a decreased risk of consecutive proteinuria (hazard ratio [HR] 0.54; 95% confidence interval [CI], 0.36–0.80) compared with non-drinkers. However, alcohol consumption of ≥69.1 g ethanol/drinking day was significantly associated with an increased risk of consecutive proteinuria (HR 1.78; 95% CI, 1.01–3.14). For subjects who reported drinking 1–3 days per week, alcohol consumption of 0.1–23.0 g ethanol/drinking day was associated with a decreased risk of consecutive proteinuria (HR 0.76; 95% CI, 0.51–1.12), and alcohol consumption of ≥69.1 g ethanol/drinking day was associated with an increased risk of consecutive proteinuria (HR 1.58; 95% CI, 0.72–3.46), but these associations did not reach statistical significance. Conclusions Men with frequent alcohol consumption of 0.1–23.0 g ethanol/drinking day had the lowest risk of consecutive proteinuria, while those with frequent alcohol consumption of ≥69.1 g ethanol/drinking day had an increased risk of consecutive proteinuria.
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Affiliation(s)
- Shinichiro Uehara
- Department of Preventive Medicine and Environmental Health, Osaka City University Graduate School of Medicine
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200
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Abstract
Podocytes are highly specialized cells of the kidney glomerulus that wrap around capillaries and that neighbor cells of the Bowman’s capsule. When it comes to glomerular filtration, podocytes play an active role in preventing plasma proteins from entering the urinary ultrafiltrate by providing a barrier comprising filtration slits between foot processes, which in aggregate represent a dynamic network of cellular extensions. Foot processes interdigitate with foot processes from adjacent podocytes and form a network of narrow and rather uniform gaps. The fenestrated endothelial cells retain blood cells but permit passage of small solutes and an overlying basement membrane less permeable to macromolecules, in particular to albumin. The cytoskeletal dynamics and structural plasticity of podocytes as well as the signaling between each of these distinct layers are essential for an efficient glomerular filtration and thus for proper renal function. The genetic or acquired impairment of podocytes may lead to foot process effacement (podocyte fusion or retraction), a morphological hallmark of proteinuric renal diseases. Here, we briefly discuss aspects of a contemporary view of podocytes in glomerular filtration, the patterns of structural changes in podocytes associated with common glomerular diseases, and the current state of basic and clinical research.
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Affiliation(s)
- Jochen Reiser
- Department of Medicine, Rush University Medical Center, Chicago, IL, USA
| | - Mehmet M Altintas
- Department of Medicine, Rush University Medical Center, Chicago, IL, USA
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