901
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Iwai T, Kume S, Chin-Kanasaki M, Kuwagata S, Araki H, Takeda N, Sugaya T, Uzu T, Maegawa H, Araki SI. Stearoyl-CoA Desaturase-1 Protects Cells against Lipotoxicity-Mediated Apoptosis in Proximal Tubular Cells. Int J Mol Sci 2016; 17:ijms17111868. [PMID: 27834856 PMCID: PMC5133868 DOI: 10.3390/ijms17111868] [Citation(s) in RCA: 41] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Revised: 10/31/2016] [Accepted: 11/03/2016] [Indexed: 01/13/2023] Open
Abstract
Saturated fatty acid (SFA)-related lipotoxicity is a pathogenesis of diabetes-related renal proximal tubular epithelial cell (PTEC) damage, closely associated with a progressive decline in renal function. This study was designed to identify a free fatty acid (FFA) metabolism-related enzyme that can protect PTECs from SFA-related lipotoxicity. Among several enzymes involved in FFA metabolism, we identified stearoyl-CoA desaturase-1 (SCD1), whose expression level significantly decreased in the kidneys of high-fat diet (HFD)-induced diabetic mice, compared with non-diabetic mice. SCD1 is an enzyme that desaturates SFAs, converting them to monounsaturated fatty acids (MUFAs), leading to the formation of neutral lipid droplets. In culture, retrovirus-mediated overexpression of SCD1 or MUFA treatment significantly ameliorated SFA-induced apoptosis in PTECs by enhancing intracellular lipid droplet formation. In contrast, siRNA against SCD1 exacerbated the apoptosis. Both overexpression of SCD1 and MUFA treatment reduced SFA-induced apoptosis via reducing endoplasmic reticulum stress in cultured PTECs. Thus, HFD-induced decrease in renal SCD1 expression may play a pathogenic role in lipotoxicity-induced renal injury, and enhancing SCD1-mediated desaturation of SFA and subsequent formation of neutral lipid droplets may become a promising therapeutic target to reduce SFA-induced lipotoxicity. The present study provides a novel insight into lipotoxicity in the pathogenesis of diabetic nephropathy.
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Affiliation(s)
- Tamaki Iwai
- Department of Medicine, Shiga University of Medical Science, Tsukinowa-cho, Seta, Otsu, Shiga 520-2192, Japan.
| | - Shinji Kume
- Department of Medicine, Shiga University of Medical Science, Tsukinowa-cho, Seta, Otsu, Shiga 520-2192, Japan.
| | - Masami Chin-Kanasaki
- Department of Medicine, Shiga University of Medical Science, Tsukinowa-cho, Seta, Otsu, Shiga 520-2192, Japan.
| | - Shogo Kuwagata
- Department of Medicine, Shiga University of Medical Science, Tsukinowa-cho, Seta, Otsu, Shiga 520-2192, Japan.
| | - Hisazumi Araki
- Department of Medicine, Shiga University of Medical Science, Tsukinowa-cho, Seta, Otsu, Shiga 520-2192, Japan.
| | - Naoko Takeda
- Department of Medicine, Shiga University of Medical Science, Tsukinowa-cho, Seta, Otsu, Shiga 520-2192, Japan.
| | - Takeshi Sugaya
- Department of Internal Medicine, St. Marianna University School of Medicine, Kawasaki, Kanagawa 216-8511, Japan.
| | - Takashi Uzu
- Department of Medicine, Shiga University of Medical Science, Tsukinowa-cho, Seta, Otsu, Shiga 520-2192, Japan.
| | - Hiroshi Maegawa
- Department of Medicine, Shiga University of Medical Science, Tsukinowa-cho, Seta, Otsu, Shiga 520-2192, Japan.
| | - Shin-Ichi Araki
- Department of Medicine, Shiga University of Medical Science, Tsukinowa-cho, Seta, Otsu, Shiga 520-2192, Japan.
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902
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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: 212] [Impact Index Per Article: 26.5] [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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903
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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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904
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Long J, Badal SS, Ye Z, Wang Y, Ayanga BA, Galvan DL, Green NH, Chang BH, Overbeek PA, Danesh FR. Long noncoding RNA Tug1 regulates mitochondrial bioenergetics in diabetic nephropathy. J Clin Invest 2016; 126:4205-4218. [PMID: 27760051 DOI: 10.1172/jci87927] [Citation(s) in RCA: 290] [Impact Index Per Article: 36.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2016] [Accepted: 08/18/2016] [Indexed: 12/29/2022] Open
Abstract
The regulatory roles of long noncoding RNAs (lncRNAs) in transcriptional coactivators are still largely unknown. Here, we have shown that the peroxisome proliferator-activated receptor γ (PPARγ) coactivator α (PGC-1α, encoded by Ppargc1a) is functionally regulated by the lncRNA taurine-upregulated gene 1 (Tug1). Further, we have described a role for Tug1 in the regulation of mitochondrial function in podocytes. Using a murine model of diabetic nephropathy (DN), we performed an unbiased RNA-sequencing (RNA-seq) analysis of kidney glomeruli and identified Tug1 as a differentially expressed lncRNA in the diabetic milieu. Podocyte-specific overexpression (OE) of Tug1 in diabetic mice improved the biochemical and histological features associated with DN. Unexpectedly, we found that Tug1 OE rescued the expression of PGC-1α and its transcriptional targets. Tug1 OE was also associated with improvements in mitochondrial bioenergetics in the podocytes of diabetic mice. Mechanistically, we found that the interaction between Tug1 and PGC-1α promotes the binding of PGC-1α to its own promoter. We identified a Tug1-binding element (TBE) upstream of the Ppargc1a gene and showed that Tug1 binds with the TBE to enhance Ppargc1a promoter activity. These findings indicate that a direct interaction between PGC-1α and Tug1 modulates mitochondrial bioenergetics in podocytes in the diabetic milieu.
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905
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Lovisa S, Zeisberg M, Kalluri R. Partial Epithelial-to-Mesenchymal Transition and Other New Mechanisms of Kidney Fibrosis. Trends Endocrinol Metab 2016; 27:681-695. [PMID: 27372267 DOI: 10.1016/j.tem.2016.06.004] [Citation(s) in RCA: 176] [Impact Index Per Article: 22.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2016] [Revised: 06/06/2016] [Accepted: 06/06/2016] [Indexed: 12/24/2022]
Abstract
Kidney fibrosis is the unavoidable consequence of chronic kidney disease irrespective of the primary underlying insult. It is a complex phenomenon governed by the interplay between different cellular components and intricate networks of signaling pathways, which together lead to loss of renal functionality and replacement of kidney parenchyma with scar tissue. An immense effort has recently been made to understand the molecular and cellular mechanisms leading to kidney fibrosis. The cellular protagonists of this process include myofibroblasts, tubular epithelial cells, endothelial cells, and immune cells. We discuss here the most recent findings, including partial epithelial-to-mesenchymal transition (EMT), in the initiation and progression of tissue fibrosis and chronic kidney disease (CKD). A deep understanding of these mechanisms will allow the development of effective therapies.
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Affiliation(s)
- Sara Lovisa
- Department of Cancer Biology, Metastasis Research Center, University of Texas M.D. Anderson Cancer Center, Houston, TX 77054, USA
| | - Michael Zeisberg
- Department of Nephrology and Rheumatology, Göttingen University Medical Center, Georg August University, Göttingen, Germany
| | - Raghu Kalluri
- Department of Cancer Biology, Metastasis Research Center, University of Texas M.D. Anderson Cancer Center, Houston, TX 77054, USA; Department of Molecular and Cellular Biology, Baylor College of Medicine, Houston, TX 77030, USA; Department of Bioengineering, Rice University, Houston, TX 77030, USA.
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906
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Sas KM, Kayampilly P, Byun J, Nair V, Hinder LM, Hur J, Zhang H, Lin C, Qi NR, Michailidis G, Groop PH, Nelson RG, Darshi M, Sharma K, Schelling JR, Sedor JR, Pop-Busui R, Weinberg JM, Soleimanpour SA, Abcouwer SF, Gardner TW, Burant CF, Feldman EL, Kretzler M, Brosius FC, Pennathur S. Tissue-specific metabolic reprogramming drives nutrient flux in diabetic complications. JCI Insight 2016; 1:e86976. [PMID: 27699244 PMCID: PMC5033761 DOI: 10.1172/jci.insight.86976] [Citation(s) in RCA: 173] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2016] [Accepted: 08/16/2016] [Indexed: 12/15/2022] Open
Abstract
Diabetes is associated with altered cellular metabolism, but how altered metabolism contributes to the development of diabetic complications is unknown. We used the BKS db/db diabetic mouse model to investigate changes in carbohydrate and lipid metabolism in kidney cortex, peripheral nerve, and retina. A systems approach using transcriptomics, metabolomics, and metabolic flux analysis identified tissue-specific differences, with increased glucose and fatty acid metabolism in the kidney, a moderate increase in the retina, and a decrease in the nerve. In the kidney, increased metabolism was associated with enhanced protein acetylation and mitochondrial dysfunction. To confirm these findings in human disease, we analyzed diabetic kidney transcriptomic data and urinary metabolites from a cohort of Southwestern American Indians. The urinary findings were replicated in 2 independent patient cohorts, the Finnish Diabetic Nephropathy and the Family Investigation of Nephropathy and Diabetes studies. Increased concentrations of TCA cycle metabolites in urine, but not in plasma, predicted progression of diabetic kidney disease, and there was an enrichment of pathways involved in glycolysis and fatty acid and amino acid metabolism. Our findings highlight tissue-specific changes in metabolism in complication-prone tissues in diabetes and suggest that urinary TCA cycle intermediates are potential prognostic biomarkers of diabetic kidney disease progression.
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Affiliation(s)
| | | | | | - Viji Nair
- Department of Internal Medicine
- Department of Computational Medicine and Bioinformatics
| | - Lucy M. Hinder
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA
| | - Junguk Hur
- Department of Biomedical Sciences, University of North Dakota School of Medicine and Health Sciences, Grand Forks, North Dakota, USA
| | | | | | | | - George Michailidis
- Department of Statistics, University of Michigan, Ann Arbor, Michigan, USA
| | - Per-Henrik Groop
- Folkhälsan Institute of Genetics, Folkhälsan Research Center, Biomedicum Helsinki, Helsinki, Finland
- Abdominal Center Nephrology, University of Helsinki and Helsinki University Hospital, Helsinki, Finland
- Baker IDI Heart and Diabetes Institute, Melbourne, Australia
| | - Robert G. Nelson
- Diabetes Epidemiology and Clinical Research Section, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Phoenix, Arizona, USA
| | - Manjula Darshi
- Institute of Metabolomic Medicine and Center for Renal Translational Medicine, Department of Medicine, University of California San Diego, and Veterans Administration San Diego Healthcare System, La Jolla, California, USA
| | - Kumar Sharma
- Institute of Metabolomic Medicine and Center for Renal Translational Medicine, Department of Medicine, University of California San Diego, and Veterans Administration San Diego Healthcare System, La Jolla, California, USA
| | | | - John R. Sedor
- Department of Medicine
- Department of Physiology and Biophysics, Case Western Reserve University, Cleveland, Ohio, USA
| | | | | | | | | | | | - Charles F. Burant
- Department of Internal Medicine
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, USA
| | - Eva L. Feldman
- Department of Neurology, University of Michigan, Ann Arbor, Michigan, USA
| | - Matthias Kretzler
- Department of Internal Medicine
- Department of Computational Medicine and Bioinformatics
| | - Frank C. Brosius
- Department of Internal Medicine
- Department of Molecular and Integrative Physiology, University of Michigan, Ann Arbor, Michigan, USA
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907
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Islam MA, Kim S, Firdous J, Lee AY, Hong SH, Seo MK, Park TE, Yun CH, Choi YJ, Chae C, Cho CS, Cho MH. A high affinity kidney targeting by chitobionic acid-conjugated polysorbitol gene transporter alleviates unilateral ureteral obstruction in rats. Biomaterials 2016; 102:43-57. [DOI: 10.1016/j.biomaterials.2016.06.013] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2016] [Revised: 06/02/2016] [Accepted: 06/05/2016] [Indexed: 02/07/2023]
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908
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Yokoi H, Yanagita M. Targeting the fatty acid transport protein CD36, a class B scavenger receptor, in the treatment of renal disease. Kidney Int 2016; 89:740-2. [PMID: 26994570 DOI: 10.1016/j.kint.2016.01.009] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2016] [Revised: 01/10/2016] [Accepted: 01/13/2016] [Indexed: 10/22/2022]
Abstract
Augmentation of the CD36 pathway, which involves the uptake of several endogenous ligands including free fatty acids and oxidized low-density lipoprotein, contributes to the damage of proximal tubules and podocytes, whereas ablation of CD36 attenuates renal injury. Souza et al. demonstrate that 5A peptide can inhibit CD36 signaling, attenuate chronic kidney disease progression, and ameliorate inflammation and tubulointerstitial fibrosis by reducing the expression of inflammatory cytokines and chemokines, suggesting the therapeutic potential of 5A peptide against CD36-mediated renal injury.
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Affiliation(s)
- Hideki Yokoi
- Department of Nephrology, Kyoto University Graduate School of Medicine, Kyoto, Japan
| | - Motoko Yanagita
- Department of Nephrology, Kyoto University Graduate School of Medicine, Kyoto, Japan.
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909
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Peroxisome proliferator-activated receptor α-dependent renoprotection of murine kidney by irbesartan. Clin Sci (Lond) 2016; 130:1969-1981. [PMID: 27496805 DOI: 10.1042/cs20160343] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2016] [Accepted: 08/05/2016] [Indexed: 12/27/2022]
Abstract
Activation of renal peroxisome proliferator-activated receptor α (PPARα) is renoprotective, but there is no safe PPARα activator for patients with chronic kidney disease (CKD). Studies have reported that irbesartan (Irbe), an angiotensin II receptor blocker (ARB) widely prescribed for CKD, activates hepatic PPARα. However, Irbe's renal PPARα-activating effects and the role of PPARα signalling in the renoprotective effects of Irbe are unknown. Herein, these aspects were investigated in healthy kidneys of wild-type (WT) and Ppara-null (KO) mice and in the murine protein-overload nephropathy (PON) model respectively. The results were compared with those of losartan (Los), another ARB that does not activate PPARα. PPARα and its target gene expression were significantly increased only in the kidneys of Irbe-treated WT mice and not in KO or Los-treated mice, suggesting that the renal PPARα-activating effect was Irbe-specific. Irbe-treated-PON-WT mice exhibited decreased urine protein excretion, tubular injury, oxidative stress (OS), and pro-inflammatory and apoptosis-stimulating responses, and they exhibited maintenance of fatty acid metabolism. Furthermore, the expression of PPARα and that of its target mRNAs encoding proteins involved in OS, pro-inflammatory responses, apoptosis and fatty acid metabolism was maintained upon Irbe treatment. These renoprotective effects of Irbe were reversed by the PPARα antagonist MK886 and were not detected in Irbe-treated-PON-KO mice. These results suggest that Irbe activates renal PPARα and that the resultant increased PPARα signalling mediates its renoprotective effects.
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910
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Brenneman J, Hill J, Pullen S. Emerging therapeutics for the treatment of diabetic nephropathy. Bioorg Med Chem Lett 2016; 26:4394-4402. [PMID: 27520943 DOI: 10.1016/j.bmcl.2016.07.079] [Citation(s) in RCA: 26] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2016] [Revised: 07/27/2016] [Accepted: 07/29/2016] [Indexed: 02/06/2023]
Abstract
Diabetic nephropathy (DN) is the most common pathology contributing to the development of chronic kidney disease (CKD). DN caused by hypertension and unmitigated inflammation in diabetics, renders the kidneys unable to perform normally, and leads to renal fibrosis and organ failure. The increasing global prevalence of DN has been directly attributed to rising incidences of Type II diabetes, and is now the largest non-communicable cause of death worldwide. Despite the high morbidity, successful new treatments for DN are lacking. This review seeks to provide new insight on emerging clinical candidates under investigation for the treatment of DN.
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Affiliation(s)
- Jehrod Brenneman
- Small Molecule Discovery Research, Boehringer-Ingelheim Pharmaceuticals Inc., 900 Ridgebury Rd., Ridgefield, CT 06877, USA.
| | - Jon Hill
- Research Networking, Boehringer-Ingelheim Pharmaceuticals Inc., 900 Ridgebury Rd., Ridgefield, CT 06877, USA
| | - Steve Pullen
- Cardiometabolic Disease Research, Boehringer-Ingelheim Pharmaceuticals Inc., 900 Ridgebury Rd., Ridgefield, CT 06877, USA
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911
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de Moraes G, Layton CJ. Therapeutic targeting of diabetic retinal neuropathy as a strategy in preventing diabetic retinopathy. Clin Exp Ophthalmol 2016; 44:838-852. [PMID: 27334889 DOI: 10.1111/ceo.12795] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2016] [Revised: 05/22/2016] [Accepted: 06/16/2016] [Indexed: 12/21/2022]
Abstract
Diabetes causes a panretinal neurodegeneration herein termed diabetic retinal neuropathy, which manifests in the retina early and progresses throughout the disease. Clinical manifestations include changes in the ERG, perimetry, dark adaptation, contrast sensitivity and colour vision which correlate with laboratory findings of thinning of the retinal neuronal layers, increased apoptosis in neurons and activation of glial cells. Possible mechanisms include oxidative stress, neuronal AGE accumulation, altered balance of neurotrophic factors and loss of mitohormesis. Retinal neural damage precedes and is a biologically plausible cause of retinal vasculopathy later in diabetes, and this review suggests that strategies to target it directly could prevent diabetes induced blindness. The efficacy of fenofibrate in reducing retinopathy progression provides a possible proof of concept for this approach. Strategies which may target diabetic retinal neuropathy include reducing retinal metabolic demand, improving mitochondrial function with AMPK and Sirt1 activators or providing neurotrophic support with neurotrophic supplementation.
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Affiliation(s)
| | - Christopher J Layton
- Gallipoli Medical Research Foundation, Brisbane, Queensland, Australia.,University of Queensland School of Medicine, Brisbane, Queensland, Australia.,Greenslopes Private Hospital Ophthalmology Department, Greenslopes Hospital, Brisbane, Queensland, Australia
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912
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Abstract
SIGNIFICANCE Reactive oxygen species (ROS) reactive nitrogen species (RNS) and redox processes are of key importance in obesity- and diabetes-related kidney disease; however, there remains significant controversy in the field. RECENT ADVANCES New data from imaging and in vivo models of obesity and diabetic kidney disease have shed new insights into this field. In the setting of obesity- and diabetes-related kidney injury, there is a growing recognition that the major moieties of ROS and RNS are hydrogen peroxide and peroxynitrite with the enzymatic sources being NADPH oxidases and nitric oxide synthase, respectively. However, the role of mitochondrial superoxide as a driver of renal complications remains unclear. CRITICAL ISSUES Several key issues that are often not discussed are the specific ROS and RNS molecules, the source of generation, the location of production, and downstream targets. FUTURE DIRECTIONS Further understanding of the role of ROS/RNS/redox and their relationship with key signaling and metabolic pathways such as AMP-activated protein kinase (AMPK) and hypoxia-inducible factor 1-α (HIF1α) will be critical to a new understanding of kidney complications of caloric challenges and new therapeutic approaches. Antioxid. Redox Signal. 25, 208-216.
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Affiliation(s)
- Kumar Sharma
- 1 Center for Renal Translational Medicine, Institute of Metabolomic Medicine, University of California San Diego , La Jolla, California.,2 Division of Nephrology-Hypertension, Veterans Affairs San Diego Healthcare System , La Jolla, California
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913
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Galichon P, Bataille A, Vandermeersch S, Wetzstein M, Xu-Dubois YC, Legouis D, Hertig A, Buob D, Placier S, Bigé N, Lefevre G, Jouanneau C, Martin C, Iovanna JL, Rondeau E. Stress Response Gene Nupr1 Alleviates Cyclosporin A Nephrotoxicity In Vivo. J Am Soc Nephrol 2016; 28:545-556. [PMID: 27451286 DOI: 10.1681/asn.2015080936] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/23/2015] [Accepted: 06/12/2016] [Indexed: 01/19/2023] Open
Abstract
Acute tubular damage is a major cause of renal failure, especially at the early phase of kidney transplant when ischemia-reperfusion injury and cyclosporin A toxicity may coexist. The mechanisms of the latter are largely unknown. Using an mRNA microarray on microdissected tubules from a rat model of cyclosporin A toxicity to describe the related epithelial-specific transcriptional signature in vivo, we found that cyclosporin A induces pathways dependent on the transcription factor ATF4 and identified nuclear protein transcriptional regulator 1 (Nupr1), a stress response gene induced by ATF4, as the gene most strongly upregulated. Upon cyclosporin A treatment, Nupr1-deficient mice exhibited worse renal tubular lesions than wild-type mice. In primary cultures treated with cyclosporin A, renal tubular cells isolated from Nupr1-deficient mice exhibited more apoptosis and ATP depletion than cells from wild-type mice. Furthermore, cyclosporin A decreased protein synthesis and abolished proliferation in wild-type tubular cells, but only reduced proliferation in Nupr1-deficient cells. Compared with controls, mouse models of ischemia-reperfusion injury, urinary obstruction, and hypertension exhibited upregulated expression of renal NUPR1, and cyclosporin A induced Nupr1 expression in cultured human tubular epithelial cells. Finally, immunohistochemical analysis revealed strong expression of NUPR1 in the nuclei of renal proximal tubules of injured human kidney allografts, but not in those of stable allografts. Taken together, these results suggest that epithelial expression of NUPR1 has a protective role in response to injury after renal transplant and, presumably, in other forms of acute tubular damage.
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Affiliation(s)
- Pierre Galichon
- Mixed Research Unit 1155, Pierre et Marie Curie University - University Paris 06, Sorbonne Universités, Paris, France; .,Departments of Renal Intensive Care and Transplantation.,Mixed Research Unit 1155, Institut National de la Santé et de la Recherche Médicale, Paris, France; and
| | - Aurélien Bataille
- Mixed Research Unit 1155, Institut National de la Santé et de la Recherche Médicale, Paris, France; and
| | - Sophie Vandermeersch
- Mixed Research Unit 1155, Institut National de la Santé et de la Recherche Médicale, Paris, France; and
| | - Morgane Wetzstein
- Mixed Research Unit 1155, Institut National de la Santé et de la Recherche Médicale, Paris, France; and
| | - Yi-Chun Xu-Dubois
- Mixed Research Unit 1155, Institut National de la Santé et de la Recherche Médicale, Paris, France; and
| | - David Legouis
- Mixed Research Unit 1155, Institut National de la Santé et de la Recherche Médicale, Paris, France; and
| | - Alexandre Hertig
- Mixed Research Unit 1155, Pierre et Marie Curie University - University Paris 06, Sorbonne Universités, Paris, France.,Departments of Renal Intensive Care and Transplantation.,Mixed Research Unit 1155, Institut National de la Santé et de la Recherche Médicale, Paris, France; and
| | - David Buob
- Mixed Research Unit 1155, Pierre et Marie Curie University - University Paris 06, Sorbonne Universités, Paris, France.,Mixed Research Unit 1155, Institut National de la Santé et de la Recherche Médicale, Paris, France; and.,Pathology, and
| | - Sandrine Placier
- Mixed Research Unit 1155, Institut National de la Santé et de la Recherche Médicale, Paris, France; and
| | - Naïke Bigé
- Mixed Research Unit 1155, Institut National de la Santé et de la Recherche Médicale, Paris, France; and
| | - Guillaume Lefevre
- Biochemistry, Tenon Hospital, Assistance Publique - Hôpitaux de Paris, Paris, France
| | - Chantal Jouanneau
- Mixed Research Unit 1155, Institut National de la Santé et de la Recherche Médicale, Paris, France; and
| | - Caroline Martin
- Mixed Research Unit 1155, Institut National de la Santé et de la Recherche Médicale, Paris, France; and
| | - Juan Lucio Iovanna
- Unit 1068, Institut National de la Santé et de la Recherche Médicale, Marseille, France
| | - Eric Rondeau
- Mixed Research Unit 1155, Pierre et Marie Curie University - University Paris 06, Sorbonne Universités, Paris, France.,Departments of Renal Intensive Care and Transplantation.,Mixed Research Unit 1155, Institut National de la Santé et de la Recherche Médicale, Paris, France; and
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914
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Darshi M, Van Espen B, Sharma K. Metabolomics in Diabetic Kidney Disease: Unraveling the Biochemistry of a Silent Killer. Am J Nephrol 2016; 44:92-103. [PMID: 27410520 PMCID: PMC6581452 DOI: 10.1159/000447954] [Citation(s) in RCA: 59] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
The development of new therapies for chronic diseases, such as diabetic kidney disease (DKD), will continue to be hampered by lack of sufficient biomarkers that will provide insights and will be responsive to treatment interventions. The recent application of metabolomic technologies, such as nuclear magnetic resonance and mass spectroscopy, has allowed large-scale analysis of small molecules to be interrogated in a targeted or untargeted manner. Recent advances from both human and animal studies that have arisen from metabolomic analysis have recognized that mitochondrial function and fatty acid oxidation play key roles in the development and progression of DKD. Although many challenges in the technology for clinical chronic kidney disease (CKD) are yet to be validated, there will very likely be ongoing major contributions of metabolomics to develop new biochemical understanding for diabetic and CKD. The clinical application of metabolomics and accompanying bioinformatic tools will likely be a cornerstone of personalized medicine triumphs for CKD.
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Affiliation(s)
- Manjula Darshi
- Institute of Metabolomic Medicine, University of California San Diego, La Jolla, California 92093, USA
- Center for Renal Translational Medicine, University of California San Diego, La Jolla, California 92093, USA
- Division of Nephrology-Hypertension, Veterans Affairs San Diego Healthcare System, La Jolla, California 92093, USA
| | - Benjamin Van Espen
- Institute of Metabolomic Medicine, University of California San Diego, La Jolla, California 92093, USA
- Center for Renal Translational Medicine, University of California San Diego, La Jolla, California 92093, USA
| | - Kumar Sharma
- Institute of Metabolomic Medicine, University of California San Diego, La Jolla, California 92093, USA
- Center for Renal Translational Medicine, University of California San Diego, La Jolla, California 92093, USA
- Division of Nephrology-Hypertension, Veterans Affairs San Diego Healthcare System, La Jolla, California 92093, USA
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915
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Abstract
Despite major improvements in the treatment of patients with diabetes mellitus, many patients still suffer from progressive diabetic kidney disease. More research is needed to improve treatment and to understand why some patients develop complications while others do not. Mitochondrial dysfunction has turned out to be central to the pathogenesis of diabetes, and we will review some new aspects in this field and the potential for treatment. The conventional theory has been that the intracellular surplus of glucose leads to mitochondrial overproduction of superoxide that contributes to general cell damage and activation of deleterious pathways specific for diabetes complications. However, recent data suggests that reduced mitochondrial activity could be the basis for disease progression and complications through increased inflammation and pro-fibrotic factors. Physical exercise is a very strong stimulus to mitochondrial biogenesis, and we now understand many of the underlying signaling pathways. Clinical trials have also shown that training, especially high-intensity training, can delay the onset of diabetes and improve insulin resistance. Furthermore, intermittent fasting and various pharmacological agents are other potential options for stimulating mitochondrial function and reducing the risk of development and progression of diabetic kidney disease.
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Affiliation(s)
- Stein Hallan
- Department of Cancer Research and Molecular Medicine, Faculty of Medicine, NTNU - Norwegian University of Science and Technology, Trondheim, Norway
- Department of Nephrology, St Olav Hospital, Trondheim, Norway
- Institute of Metabolomic Medicine and the Center for Renal Translational Medicine, University of California San Diego, La Jolla, CA, 92093, USA
| | - Kumar Sharma
- Institute of Metabolomic Medicine and the Center for Renal Translational Medicine, University of California San Diego, La Jolla, CA, 92093, USA.
- Division of Nephrology-Hypertension, Veterans Affairs San Diego Healthcare System, La Jolla, CA, 92093, USA.
- Center for Renal Translational Medicine, University of California San Diego/Veterans Affairs San Diego Healthcare System, Stein Clinical Research Building, 4th Floor, 9500 Gilman Drive, La Jolla, CA, 92093-0711, USA.
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916
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Abstract
A recent study has highlighted the relationship between mitochondrial ATP generation and protection against organ injury following ischaemia-reperfusion injury in the kidney. Kidneys are fuel-hungry organs and only second to the heart in mitochondrial number and oxygen consumption. This article speculates on why this might be so.
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Affiliation(s)
- Josephine M Forbes
- Mater Research Institute, The University of Queensland Translational Research Institute (TRI), 37 Kent Street Brisbane, 4101 Australia; Mater Clinical School, The University of Queensland, Brisbane, 4067 Australia; Department of Medicine, The University of Melbourne, Heidelberg, 3081 Australia.
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917
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miR-93 regulates Msk2-mediated chromatin remodelling in diabetic nephropathy. Nat Commun 2016; 7:12076. [PMID: 27350436 PMCID: PMC4931323 DOI: 10.1038/ncomms12076] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2016] [Accepted: 05/26/2016] [Indexed: 01/15/2023] Open
Abstract
How the kidney responds to the metabolic cues from the environment remains a central question in kidney research. This question is particularly relevant to the pathogenesis of diabetic nephropathy (DN) in which evidence suggests that metabolic events in podocytes regulate chromatin structure. Here, we show that miR-93 is a critical metabolic/epigenetic switch in the diabetic milieu linking the metabolic state to chromatin remodelling. Mice with inducible overexpression of a miR-93 transgene exclusively in podocytes exhibit significant improvements in key features of DN. We identify miR-93 as a regulator of nucleosomal dynamics in podocytes. miR-93 has a critical role in chromatin reorganization and progression of DN by modulating its target Msk2, a histone kinase, and its substrate H3S10. These findings implicate a central role for miR-93 in high glucose-induced chromatin remodelling in the kidney, and provide evidence for a previously unrecognized role for Msk2 as a target for DN therapy. Podocyte injury is central to kidney dysfunction in diabetic nephropathy. Here the authors show that Msk2 is a target of miR-93 and this interaction mediates pathogenic chromatin remodelling in diabetic nephropathy.
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918
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Zhou D, Tan RJ, Liu Y. Sonic hedgehog signaling in kidney fibrosis: a master communicator. SCIENCE CHINA-LIFE SCIENCES 2016; 59:920-9. [PMID: 27333788 PMCID: PMC5540157 DOI: 10.1007/s11427-016-0020-y] [Citation(s) in RCA: 40] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/26/2016] [Accepted: 03/06/2016] [Indexed: 11/25/2022]
Abstract
The hedgehog signaling cascade is an evolutionarily conserved pathway that regulates multiple aspects of embryonic development and plays a decisive role in tissue homeostasis. As the best studied member of three hedgehog ligands, sonic hedgehog (Shh) is known to be associated with kidney development and tissue repair after various insults. Recent studies uncover an intrinsic link between dysregulated Shh signaling and renal fibrogenesis. In various types of chronic kidney disease (CKD), Shh is upregulated specifically in renal tubular epithelium but targets interstitial fibroblasts, thereby mediating a dynamic epithelial- mesenchymal communication (EMC). Tubule-derived Shh acts as a growth factor for interstitial fibroblasts and controls a hierarchy of fibrosis-related genes, which lead to the excessive deposition of extracellular matrix in renal interstitium. In this review, we recapitulate the principle of Shh signaling, its activation and regulation in a variety of kidney diseases. We also discuss the potential mechanisms by which Shh promotes renal fibrosis and assess the efficacy of blocking this signaling in preclinical settings. Continuing these lines of investigations will provide novel opportunities for designing effective therapies to improve CKD prognosis in patients.
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Affiliation(s)
- Dong Zhou
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, 15261, USA
| | - Roderick J Tan
- Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, 15261, USA
| | - Youhua Liu
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania, 15261, USA. .,State Key Laboratory of Organ Failure Research, National Clinical Research Center of Kidney Disease, Nanfang Hospital, Southern Medical University, Guangzhou, 510515, China.
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919
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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: 420] [Impact Index Per Article: 52.5] [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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920
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Abstract
Chronic kidney disease (CKD) represents a leading cause of death in the United States. There is no cure for this disease, with current treatment strategies relying on blood pressure control through blockade of the renin-angiotensin system. Such approaches only delay the development of end-stage kidney disease and can be associated with serious side effects. Recent identification of several novel mechanisms contributing to CKD development - including vascular changes, loss of podocytes and renal epithelial cells, matrix deposition, inflammation and metabolic dysregulation - has revealed new potential therapeutic approaches for CKD. This Review assesses emerging strategies and agents for CKD treatment, highlighting the associated challenges in their clinical development.
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921
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Tan RJ, Zhou D, Liu Y. Signaling Crosstalk between Tubular Epithelial Cells and Interstitial Fibroblasts after Kidney Injury. KIDNEY DISEASES 2016; 2:136-144. [PMID: 27921041 DOI: 10.1159/000446336] [Citation(s) in RCA: 80] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2016] [Accepted: 04/20/2016] [Indexed: 01/09/2023]
Abstract
BACKGROUND A wide variety of kidney diseases ultimately lead to tubulointerstitial damage. The initial site of injury is usually the renal tubules, with activation of fibroblasts occurring later. Self-limited disease is characterized by transient cellular activation with timed deactivation and ultimately a return to normal functioning, whereas sustained responses characterize chronic disease and the development of irreversible fibrosis. The underlying molecular and cellular mechanisms of this cascade of events remain an area of active research. Current data overwhelmingly support a role for crosstalk between the tubular epithelium and the interstitial fibroblast that mediates both repair/regeneration and progressive disease. This epithelial-mesenchymal communication (EMC) is regulated by a variety of soluble ligands binding to cell surface receptors to induce intracellular signaling events. SUMMARY EMC is an important mechanism whereby tubular epithelium and fibroblasts/mesenchymal cells crosstalk to affect renal physiology and pathology. Numerous soluble factors such as sonic hedgehog, Wnt ligands, transforming growth factor-β, hepatocyte growth factor, connective tissue growth factor, and angiotensin II all participate in bidirectional EMC. Recent studies have also identified exosomes as a vehicle to mediate EMC during kidney injury. In general, while the short-term activity of EMC factors is renoprotective, prolonged activation of these factors leads to chronic disease and fibrosis. KEY MESSAGES The discovery of a complex and intricate system of communication between tubular cells and fibroblasts is a new paradigm in our understanding of renal fibrosis. An appreciation of both their regenerative and pathologic functions will inform the development and use of targeted therapeutic interventions.
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Affiliation(s)
- Roderick J Tan
- Renal-Electrolyte Division, Department of Medicine, University of Pittsburgh School of Medicine, Pittsburgh, Pa., USA
| | - Dong Zhou
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pa., USA
| | - Youhua Liu
- Department of Pathology, University of Pittsburgh School of Medicine, Pittsburgh, Pa., USA; State Key Laboratory of Organ Failure Research, Nanfang Hospital, Southern Medical University, Guangzhou, China
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922
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Coughlan MT, Sharma K. Challenging the dogma of mitochondrial reactive oxygen species overproduction in diabetic kidney disease. Kidney Int 2016; 90:272-279. [PMID: 27217197 DOI: 10.1016/j.kint.2016.02.043] [Citation(s) in RCA: 74] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2015] [Revised: 02/21/2016] [Accepted: 02/24/2016] [Indexed: 01/02/2023]
Abstract
The paradigm that high glucose drives overproduction of superoxide from mitochondria as a unifying theory to explain end organ damage in diabetes complications has been tightly held for more than a decade. With the recent development of techniques and probes to measure the production of distinct reactive oxygen species (ROS) in vivo, this widely held dogma is now being challenged with the emerging view that specific ROS moieties are essential for the function of specific intracellular signaling pathways and represent normal mitochondrial function. This review will provide a balanced overview of the dual nature of ROS, detailing current evidence for ROS overproduction in diabetic kidney disease, with a focus on cell types and sources of ROS. The technical aspects of measurement of mitochondrial ROS, both in isolated mitochondria and emerging in vivo methods will be discussed. The counterargument, that mitochondrial ROS production is reduced in diabetic complications, is consistent with a growing recognition that stimulation of mitochondrial biogenesis and oxidative phosphorylation activity reduces inflammation and fibrosis. It is clear that there is an urgent need to fully characterize ROS production paying particular attention to spatiotemporal aspects and to factor in the relevance of ROS in the regulation of cellular signaling in the pathogenesis of diabetic kidney disease. With improved tools and real-time imaging capacity, a greater understanding of the complex role of ROS will be able to guide novel therapeutic regimens.
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Affiliation(s)
- Melinda T Coughlan
- Baker International Diabetes Institute (IDI) Heart and Diabetes Institute, Melbourne, Victoria, Australia; Department of Medicine, Central Clinical School, Monash University, Alfred Medical Research and Education Precinct, Melbourne, Victoria, Australia; Department of Epidemiology and Preventive Medicine, Monash University, Alfred Medical Research and Education Precinct, Melbourne, Victoria, Australia
| | - Kumar Sharma
- Center for Renal Translational Medicine, Division of Nephrology-Hypertension, Institute of Metabolomic Medicine, University of California-San Diego, La Jolla, California, USA; Division of Medical Genetics, Department of Medicine, University of California-San Diego, La Jolla, California, USA; Division of Nephrology-Hypertension, Veterans Affairs San Diego Healthcare System, La Jolla, California, USA.
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923
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Stern JH, Rutkowski JM, Scherer PE. Adiponectin, Leptin, and Fatty Acids in the Maintenance of Metabolic Homeostasis through Adipose Tissue Crosstalk. Cell Metab 2016; 23:770-84. [PMID: 27166942 PMCID: PMC4864949 DOI: 10.1016/j.cmet.2016.04.011] [Citation(s) in RCA: 668] [Impact Index Per Article: 83.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
Metabolism research has made tremendous progress over the last several decades in establishing the adipocyte as a central rheostat in the regulation of systemic nutrient and energy homeostasis. Operating at multiple levels of control, the adipocyte communicates with organ systems to adjust gene expression, glucoregulatory hormone exocytosis, enzymatic reactions, and nutrient flux to equilibrate the metabolic demands of a positive or negative energy balance. The identification of these mechanisms has great potential to identify novel targets for the treatment of diabetes and related metabolic disorders. Herein, we review the central role of the adipocyte in the maintenance of metabolic homeostasis, highlighting three critical mediators: adiponectin, leptin, and fatty acids.
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Affiliation(s)
- Jennifer H Stern
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Joseph M Rutkowski
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Philipp E Scherer
- Touchstone Diabetes Center, Department of Internal Medicine, The University of Texas Southwestern Medical Center, Dallas, TX 75390, USA.
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924
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Zhu F, Liu W, Li T, Wan J, Tian J, Zhou Z, Li H, Liu Y, Hou FF, Nie J. Numb contributes to renal fibrosis by promoting tubular epithelial cell cycle arrest at G2/M. Oncotarget 2016; 7:25604-19. [PMID: 27016419 PMCID: PMC5041930 DOI: 10.18632/oncotarget.8238] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2015] [Accepted: 03/06/2016] [Indexed: 12/17/2022] Open
Abstract
Numb is a multifunctional protein involved in diverse cellular processes. However, the function of Numb in kidney remains unclear. Here, we reported that Numb is expressed in renal tubules and glomeruli in normal adult kidney. Numb expression was upregulated in fibrotic kidneys induced by unilateral ureteral obstruction (UUO) in mice as well as in human fibrotic kidney tissues. Numb overexpression in cultured proximal tubular cells increased the G2/M cell population and upregulated the expression of TGF-β1 and CTGF. Whereas, proximal tubule Numb knockout (PEPCK-Numb-KO) mice showed reduced G2/M arrest, decreased expression of TGF-β1 and CTGF, and attenuated fibrotic lesions due to either UUO or unilateral ischemia reperfusion nephropathy. Inhibiting p53 activity by pifithrin-` dramatically mitigated Numb-induced G2/M arrest, indicating that Numb potentiates G2/M arrest via stabilizing p53 protein. Together, these data suggest that Numb is a potential target for anti-fibrosis therapy.
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Affiliation(s)
- Fengxin Zhu
- State Key Laboratory of Organ Failure Research, National Clinical Research Center of Kidney Disease, Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, P.R. China
| | - Wei Liu
- Department of Nephrology, Guangdong General Hospital, Guangdong Academy of Medical Sciences, Guangdong Geriatric Institute, Guangzhou, P.R. China
| | - Tang Li
- The VIP Medical Center, The Third Affiliated Hospital of Sun Yat-Sen University, Guangzhou, P.R. China
| | - Jiao Wan
- State Key Laboratory of Organ Failure Research, National Clinical Research Center of Kidney Disease, Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, P.R. China
| | - Jianwei Tian
- State Key Laboratory of Organ Failure Research, National Clinical Research Center of Kidney Disease, Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, P.R. China
| | - Zhanmei Zhou
- State Key Laboratory of Organ Failure Research, National Clinical Research Center of Kidney Disease, Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, P.R. China
| | - Hao Li
- State Key Laboratory of Organ Failure Research, National Clinical Research Center of Kidney Disease, Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, P.R. China
| | - Youhua Liu
- State Key Laboratory of Organ Failure Research, National Clinical Research Center of Kidney Disease, Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, P.R. China
| | - Fan Fan Hou
- State Key Laboratory of Organ Failure Research, National Clinical Research Center of Kidney Disease, Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, P.R. China
| | - Jing Nie
- State Key Laboratory of Organ Failure Research, National Clinical Research Center of Kidney Disease, Division of Nephrology, Nanfang Hospital, Southern Medical University, Guangzhou, P.R. China
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925
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Abstract
The longstanding focus in chronic kidney disease (CKD) research has been on the glomerulus, which is sensible because this is where glomerular filtration occurs, and a large proportion of progressive CKD is associated with significant glomerular pathology. However, it has been known for decades that tubular atrophy is also a hallmark of CKD and that it is superior to glomerular pathology as a predictor of glomerular filtration rate decline in CKD. Nevertheless, there are vastly fewer studies that investigate the causes of tubular atrophy, and fewer still that identify potential therapeutic targets. The purpose of this review is to discuss plausible mechanisms of tubular atrophy, including tubular epithelial cell apoptosis, cell senescence, peritubular capillary rarefaction and downstream tubule ischemia, oxidative stress, atubular glomeruli, epithelial-to-mesenchymal transition, interstitial inflammation, lipotoxicity and Na(+)/H(+) exchanger-1 inactivation. Once a a better understanding of tubular atrophy (and interstitial fibrosis) pathophysiology has been obtained, it might then be possible to consider tandem glomerular and tubular therapeutic strategies, in a manner similar to cancer chemotherapy regimens, which employ multiple drugs to simultaneously target different mechanistic pathways.
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926
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Jadhav S, Ajay AK, Trivedi P, Seematti J, Pellegrini K, Craciun F, Vaidya VS. RNA-binding Protein Musashi Homologue 1 Regulates Kidney Fibrosis by Translational Inhibition of p21 and Numb mRNA. J Biol Chem 2016; 291:14085-14094. [PMID: 27129280 DOI: 10.1074/jbc.m115.713289] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2015] [Indexed: 11/06/2022] Open
Abstract
RNA-binding proteins (RBPs) are recognized as key posttranscriptional regulators that not only modulate the spatiotemporal expression of genes during organism development but also regulate disease pathogenesis. Very limited information exists on the potential role of RBPs in modulating kidney fibrosis, which is a major hallmark of chronic kidney disease. Here, we report a novel mechanism in kidney fibrosis involving a RBP, Musashi homologue 1 (Msi1), which is expressed in tubular epithelial cells. Using two mechanistically distinct mouse models of kidney fibrosis, we show that Msi1 protein levels are significantly down-regulated in the kidneys following fibrosis. We found that Msi1 functions by negatively regulating the translation of its target mRNAs, p21 and Numb, whose protein levels are markedly increased in kidney fibrosis. Also, Msi1 overexpression and knockdown in kidney epithelial cells cause p21- and Numb-mediated cell cycle arrest. Furthermore, we observed that Numb looses its characteristic membrane localization in fibrotic kidneys and therefore is likely unable to inhibit Notch resulting in tubular cell death. Oleic acid is a known inhibitor of Msi1 and injecting oleic acid followed by unilateral ureteral obstruction surgery in mice resulted in enhanced fibrosis compared with the control group, indicating that inhibiting Msi1 activity renders the mice more susceptible to fibrosis. Given that deregulated fatty acid metabolism plays a key role in kidney fibrosis, these results demonstrate a novel connection between fatty acid and Msi1, an RNA-binding protein, in kidney fibrosis.
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Affiliation(s)
- Shreyas Jadhav
- Department of Medicine, Renal Division, Brigham and Women's Hospital, Boston, Massachusetts 02115
| | - Amrendra K Ajay
- Department of Medicine, Renal Division, Brigham and Women's Hospital, Boston, Massachusetts 02115
| | - Priyanka Trivedi
- Department of Medicine, Renal Division, Brigham and Women's Hospital, Boston, Massachusetts 02115
| | - Jenifer Seematti
- Department of Medicine, Renal Division, Brigham and Women's Hospital, Boston, Massachusetts 02115
| | - Kathryn Pellegrini
- Department of Medicine, Renal Division, Brigham and Women's Hospital, Boston, Massachusetts 02115
| | - Florin Craciun
- Department of Medicine, Renal Division, Brigham and Women's Hospital, Boston, Massachusetts 02115
| | - Vishal S Vaidya
- Department of Medicine, Renal Division, Brigham and Women's Hospital, Boston, Massachusetts 02115,; Harvard Program in Therapeutic Sciences, Harvard Medical School, Boston, Massachusetts 02115; Department of Environmental Health, Harvard T. H. Chan School of Public Health, Boston, Massachusetts 02115.
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927
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Furrow E, Jaeger JQ, Parker VJ, Hinchcliff KW, Johnson SE, Murdoch SJ, de Boer IH, Sherding RG, Brunzell JD. Proteinuria and lipoprotein lipase activity in Miniature Schnauzer dogs with and without hypertriglyceridemia. Vet J 2016; 212:83-9. [PMID: 27256031 DOI: 10.1016/j.tvjl.2016.04.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2015] [Revised: 03/23/2016] [Accepted: 04/17/2016] [Indexed: 01/25/2023]
Abstract
Spontaneous hyperlipidemia in rats causes glomerular disease. Idiopathic hypertriglyceridemia (HTG) is prevalent in Miniature Schnauzers, but its relationship with proteinuria is unknown. Decreased activity of major lipid metabolism enzymes, lipoprotein lipase (LPL) and hepatic lipase (HL), may play a role in the cyclic relationship between hyperlipidemia and proteinuria. These enzymes have also not been previously investigated in Miniature Schnauzers. The aims of this study were to determine the relationship between HTG and proteinuria in Miniature Schnauzers and to measure LPL and HL activities in a subset of dogs. Fifty-seven Miniature Schnauzers were recruited (34 with and 23 without HTG). Fasting serum triglyceride concentrations and urine protein-to-creatinine ratios (UPC) were measured in all dogs, and LPL and HL activities were determined in 17 dogs (8 with and 9 without HTG). There was a strong positive correlation between triglyceride concentration and UPC (r = 0.77-0.83, P < 0.001). Proteinuria (UPC ≥ 0.5) was present in 60% of dogs with HTG and absent from all dogs without HTG (P < 0.001). Proteinuric dogs were not azotemic or hypoalbuminemic. Dogs with HTG had a 65% reduction in LPL activity relative to dogs without HTG (P < 0.001); HL activity did not differ. Proteinuria occurs with HTG in Miniature Schnauzers and could be due to lipid-induced glomerular injury. Reduced LPL activity may contribute to the severity of HTG, but further assay validation is required.
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Affiliation(s)
- E Furrow
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, University of Minnesota, St. Paul, MN 55113, USA.
| | - J Q Jaeger
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210, USA
| | - V J Parker
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210, USA
| | - K W Hinchcliff
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210, USA
| | - S E Johnson
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210, USA
| | - S J Murdoch
- Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, University of Washington, Seattle, WA 98195, USA
| | - I H de Boer
- Division of Nephrology, Department of Medicine, University of Washington, Seattle, WA 98104, USA
| | - R G Sherding
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, The Ohio State University, Columbus, OH 43210, USA
| | - J D Brunzell
- Division of Metabolism, Endocrinology and Nutrition, Department of Medicine, University of Washington, Seattle, WA 98195, USA
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928
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Coughlan MT, Higgins GC, Nguyen TV, Penfold SA, Thallas-Bonke V, Tan SM, Ramm G, Van Bergen NJ, Henstridge DC, Sourris KC, Harcourt BE, Trounce IA, Robb PM, Laskowski A, McGee SL, Genders AJ, Walder K, Drew BG, Gregorevic P, Qian H, Thomas MC, Jerums G, Macisaac RJ, Skene A, Power DA, Ekinci EI, Wijeyeratne XW, Gallo LA, Herman-Edelstein M, Ryan MT, Cooper ME, Thorburn DR, Forbes JM. Deficiency in Apoptosis-Inducing Factor Recapitulates Chronic Kidney Disease via Aberrant Mitochondrial Homeostasis. Diabetes 2016; 65:1085-98. [PMID: 26822084 DOI: 10.2337/db15-0864] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/24/2015] [Accepted: 01/10/2016] [Indexed: 11/13/2022]
Abstract
Apoptosis-inducing factor (AIF) is a mitochondrial flavoprotein with dual roles in redox signaling and programmed cell death. Deficiency in AIF is known to result in defective oxidative phosphorylation (OXPHOS), via loss of complex I activity and assembly in other tissues. Because the kidney relies on OXPHOS for metabolic homeostasis, we hypothesized that a decrease in AIF would result in chronic kidney disease (CKD). Here, we report that partial knockdown of Aif in mice recapitulates many features of CKD, in association with a compensatory increase in the mitochondrial ATP pool via a shift toward mitochondrial fusion, excess mitochondrial reactive oxygen species production, and Nox4 upregulation. However, despite a 50% lower AIF protein content in the kidney cortex, there was no loss of complex I activity or assembly. When diabetes was superimposed onto Aif knockdown, there were extensive changes in mitochondrial function and networking, which augmented the renal lesion. Studies in patients with diabetic nephropathy showed a decrease in AIF within the renal tubular compartment and lower AIFM1 renal cortical gene expression, which correlated with declining glomerular filtration rate. Lentiviral overexpression of Aif1m rescued glucose-induced disruption of mitochondrial respiration in human primary proximal tubule cells. These studies demonstrate that AIF deficiency is a risk factor for the development of diabetic kidney disease.
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Affiliation(s)
- Melinda T Coughlan
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia Department of Medicine, Central Clinical School, Monash University, Alfred Medical Research and Education Precinct, Melbourne, Victoria, Australia Department of Epidemiology and Preventive Medicine, Monash University, Alfred Medical Research and Education Precinct, Melbourne, Victoria, Australia
| | - Gavin C Higgins
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Tuong-Vi Nguyen
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Sally A Penfold
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | | | - Sih Min Tan
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia Department of Medicine, Central Clinical School, Monash University, Alfred Medical Research and Education Precinct, Melbourne, Victoria, Australia
| | - Georg Ramm
- Membrane Biology Group, Department of Biochemistry and Molecular Biology, Monash University, Clayton Campus, Victoria, Australia
| | - Nicole J Van Bergen
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Victoria, Australia
| | | | - Karly C Sourris
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia Department of Medicine, Central Clinical School, Monash University, Alfred Medical Research and Education Precinct, Melbourne, Victoria, Australia
| | - Brooke E Harcourt
- Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
| | - Ian A Trounce
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne, Victoria, Australia
| | - Portia M Robb
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Adrienne Laskowski
- Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
| | - Sean L McGee
- Metabolic Research Unit, Deakin University, Waurn Ponds, Victoria, Australia
| | - Amanda J Genders
- Metabolic Research Unit, Deakin University, Waurn Ponds, Victoria, Australia
| | - Ken Walder
- Metabolic Research Unit, Deakin University, Waurn Ponds, Victoria, Australia
| | - Brian G Drew
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Paul Gregorevic
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Hongwei Qian
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - Merlin C Thomas
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia
| | - George Jerums
- Endocrine Centre, Austin Health, Repatriation Campus, Heidelberg West, Victoria, Australia
| | - Richard J Macisaac
- Departments of Endocrinology and Diabetes, St Vincent's Hospital Melbourne and The University of Melbourne, Fitzroy, Victoria, Australia
| | - Alison Skene
- Department of Anatomical Pathology, Austin Health, Heidelberg, Victoria, Australia
| | - David A Power
- Department of Nephrology and Institute for Breathing and Sleep, Austin Health, Heidelberg, Victoria, Australia Department of Medicine, Austin Health and The University of Melbourne, Parkville, Victoria, Australia
| | - Elif I Ekinci
- Endocrine Centre, Austin Health, Repatriation Campus, Heidelberg West, Victoria, Australia Department of Medicine, Austin Health and The University of Melbourne, Parkville, Victoria, Australia Menzies School of Health Research, Darwin, Northern Territory, Australia
| | | | - Linda A Gallo
- Glycation and Diabetes Group, Mater Research Institute-University of Queensland, Translational Research Institute, Woolloongabba, South Brisbane, Queensland, Australia
| | - Michal Herman-Edelstein
- The Felsenstein Medical Research Center and Department of Nephrology and Hypertension, Rabin Medical Center, Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel
| | - Michael T Ryan
- Mitochondria Laboratory, Department of Biochemistry and Molecular Biology, Monash University, Clayton, Victoria, Australia
| | - Mark E Cooper
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia Department of Medicine, Central Clinical School, Monash University, Alfred Medical Research and Education Precinct, Melbourne, Victoria, Australia
| | - David R Thorburn
- Murdoch Children's Research Institute, Royal Children's Hospital, Parkville, Victoria, Australia
| | - Josephine M Forbes
- Baker IDI Heart and Diabetes Institute, Melbourne, Victoria, Australia Glycation and Diabetes Group, Mater Research Institute-University of Queensland, Translational Research Institute, Woolloongabba, South Brisbane, Queensland, Australia School of Medicine, Mater Clinical School, The University of Queensland, St. Lucia, Queensland, Australia
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929
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Miyamoto S, Hsu CC, Hamm G, Darshi M, Diamond-Stanic M, Declèves AE, Slater L, Pennathur S, Stauber J, Dorrestein PC, Sharma K. Mass Spectrometry Imaging Reveals Elevated Glomerular ATP/AMP in Diabetes/obesity and Identifies Sphingomyelin as a Possible Mediator. EBioMedicine 2016; 7:121-34. [PMID: 27322466 PMCID: PMC4909366 DOI: 10.1016/j.ebiom.2016.03.033] [Citation(s) in RCA: 87] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2016] [Revised: 03/11/2016] [Accepted: 03/21/2016] [Indexed: 01/01/2023] Open
Abstract
AMP-activated protein kinase (AMPK) is suppressed in diabetes and may be due to a high ATP/AMP ratio, however the quantitation of nucleotides in vivo has been extremely difficult. Via matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) to localize renal nucleotides we found that the diabetic kidney had a significant increase in glomerular ATP/AMP ratio. Untargeted MALDI-MSI analysis revealed that a specific sphingomyelin species (SM(d18:1/16:0)) accumulated in the glomeruli of diabetic and high-fat diet-fed mice compared with wild-type controls. In vitro studies in mesangial cells revealed that exogenous addition of SM(d18:1/16:0) significantly elevated ATP via increased glucose consumption and lactate production with a consequent reduction of AMPK and PGC1α. Furthermore, inhibition of sphingomyelin synthases reversed these effects. Our findings suggest that AMPK is reduced in the diabetic kidney due to an increase in the ATP/AMP ratio and that SM(d18:1/16:0) could be responsible for the enhanced ATP production via activation of the glycolytic pathway. MALDI-MSI revealed an increase in glomerular ATP/AMP ratio in the diabetic kidney. SM(d18:1/16:0) is increased in the glomeruli of diabetic and high-fat diet-fed mice. SM(d18:1/16:0) stimulated ATP production via enhanced aerobic glycolysis and reduced AMPK activity in mesangial cells. AMPK is known to be suppressed in states of high ATP/AMP ratio but the measurement of nucleotides in vivo has been difficult. Miyamoto et al. utilize matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) to investigate the distribution of nucleotides and find an increase in glomerular ATP/AMP ratio in the diabetic kidney. Untargeted MALDI-MSI revealed that sphingomyelin(d18:1/16:0) is accumulated in the glomeruli of diabetic and high-fat diet-fed mice compared with controls. Sphingomyelin(d18:1/16:0) promotes ATP production in mesangial cells via activation of the glycolytic pathway. The inhibition of sphingomyelin(d18:1/16:0) synthesis may lead to novel therapeutic targets for the treatment of caloric-induced CKD.
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Affiliation(s)
- Satoshi Miyamoto
- Institute of Metabolomic Medicine, University of California San Diego, La Jolla, CA 92093, USA; Center for Renal Translational Medicine, Division of Nephrology-Hypertension, University of California San Diego, La Jolla, CA 92093, USA; Division of Nephrology-Hypertension, Veterans Affairs San Diego Healthcare System, La Jolla, CA 92093, USA; Department of Nephrology, Rheumatology, Endocrinology and Metabolism, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical Sciences, Okayama 700-8558, Japan
| | - Cheng-Chih Hsu
- Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA 92093, USA; Department of Chemistry, National Taiwan University, Taipei 106, Taiwan
| | - Gregory Hamm
- ImaBiotech, MS Imaging Department, Lille 59120, France
| | - Manjula Darshi
- Institute of Metabolomic Medicine, University of California San Diego, La Jolla, CA 92093, USA; Center for Renal Translational Medicine, Division of Nephrology-Hypertension, University of California San Diego, La Jolla, CA 92093, USA
| | - Maggie Diamond-Stanic
- Institute of Metabolomic Medicine, University of California San Diego, La Jolla, CA 92093, USA; Center for Renal Translational Medicine, Division of Nephrology-Hypertension, University of California San Diego, La Jolla, CA 92093, USA; Division of Nephrology-Hypertension, Veterans Affairs San Diego Healthcare System, La Jolla, CA 92093, USA
| | - Anne-Emilie Declèves
- Center for Renal Translational Medicine, Division of Nephrology-Hypertension, University of California San Diego, La Jolla, CA 92093, USA
| | - Larkin Slater
- Institute of Metabolomic Medicine, University of California San Diego, La Jolla, CA 92093, USA; Center for Renal Translational Medicine, Division of Nephrology-Hypertension, University of California San Diego, La Jolla, CA 92093, USA; Division of Nephrology-Hypertension, Veterans Affairs San Diego Healthcare System, La Jolla, CA 92093, USA
| | | | | | - Pieter C Dorrestein
- Institute of Metabolomic Medicine, University of California San Diego, La Jolla, CA 92093, USA; Department of Chemistry and Biochemistry, University of California San Diego, La Jolla, CA 92093, USA; Skaggs School of Pharmacy and Pharmaceutical Sciences, University of California San Diego, La Jolla, CA 92093, USA
| | - Kumar Sharma
- Institute of Metabolomic Medicine, University of California San Diego, La Jolla, CA 92093, USA; Center for Renal Translational Medicine, Division of Nephrology-Hypertension, University of California San Diego, La Jolla, CA 92093, USA; Division of Nephrology-Hypertension, Veterans Affairs San Diego Healthcare System, La Jolla, CA 92093, USA.
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930
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Zhang Y, Ma KL, Ruan XZ, Liu BC. Dysregulation of the Low-Density Lipoprotein Receptor Pathway Is Involved in Lipid Disorder-Mediated Organ Injury. Int J Biol Sci 2016; 12:569-79. [PMID: 27019638 PMCID: PMC4807419 DOI: 10.7150/ijbs.14027] [Citation(s) in RCA: 79] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2015] [Accepted: 02/26/2016] [Indexed: 12/12/2022] Open
Abstract
The low-density lipoprotein receptor (LDLR) pathway is a negative feedback system that plays important roles in the regulation of plasma and intracellular cholesterol homeostasis. To maintain a cholesterol homeostasis, LDLR expression is tightly regulated by sterol regulatory element-binding protein-2 (SREBP-2) and SREBP cleavage-activating protein (SCAP) in transcriptional level and by proprotein convertase subtilisin/kexin type 9 (PCSK9) in posttranscriptional level. The dysregulation of LDLR expression results in abnormal lipid accumulation in cells and tissues, such as vascular smooth muscle cells, hepatic cells, renal mesangial cells, renal tubular cells and podocytes. It has been demonstrated that inflammation, renin-angiotensin system (RAS) activation, and hyperglycemia induce the disruption of LDLR pathway, which might contribute to lipid disorder-mediated organ injury (atherosclerosis, non-alcoholic fatty liver disease, kidney fibrosis, etc). The mammalian target of rapamycin (mTOR) pathway is a critical mediator in the disruption of LDLR pathway caused by pathogenic factors. The mTOR complex1 activation upregulates LDLR expression at the transcriptional and posttranscriptional levels, consequently resulting in lipid deposition. This paper mainly reviews the mechanisms for the dysregulation of LDLR pathway and its roles in lipid disorder-mediated organ injury under various pathogenic conditions. Understanding these mechanisms leading to the abnormality of LDLR expression contributes to find potential new drug targets in lipid disorder-mediated diseases.
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931
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Lan R, Geng H, Singha PK, Saikumar P, Bottinger EP, Weinberg JM, Venkatachalam MA. Mitochondrial Pathology and Glycolytic Shift during Proximal Tubule Atrophy after Ischemic AKI. J Am Soc Nephrol 2016; 27:3356-3367. [PMID: 27000065 DOI: 10.1681/asn.2015020177] [Citation(s) in RCA: 211] [Impact Index Per Article: 26.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2015] [Accepted: 02/03/2016] [Indexed: 02/01/2023] Open
Abstract
During recovery by regeneration after AKI, proximal tubule cells can fail to redifferentiate, undergo premature growth arrest, and become atrophic. The atrophic tubules display pathologically persistent signaling increases that trigger production of profibrotic peptides, proliferation of interstitial fibroblasts, and fibrosis. We studied proximal tubules after ischemia-reperfusion injury (IRI) to characterize possible mitochondrial pathologies and alterations of critical enzymes that govern energy metabolism. In rat kidneys, tubules undergoing atrophy late after IRI but not normally recovering tubules showed greatly reduced mitochondrial number, with rounded profiles, and large autophagolysosomes. Studies after IRI of kidneys in mice, done in parallel, showed large scale loss of the oxidant-sensitive mitochondrial protein Mpv17L. Renal expression of hypoxia markers also increased after IRI. During early and late reperfusion after IRI, kidneys exhibited increased lactate and pyruvate content and hexokinase activity, which are indicators of glycolysis. Furthermore, normally regenerating tubules as well as tubules undergoing atrophy exhibited increased glycolytic enzyme expression and inhibitory phosphorylation of pyruvate dehydrogenase. TGF-β antagonism prevented these effects. Our data show that the metabolic switch occurred early during regeneration after injury and was reversed during normal tubule recovery but persisted and became progressively more severe in tubule cells that failed to redifferentiate. In conclusion, irreversibility of the metabolic switch, taking place in the context of hypoxia, high TGF-β signaling and depletion of mitochondria characterizes the development of atrophy in proximal tubule cells and may contribute to the renal pathology after AKI.
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Affiliation(s)
- Rongpei Lan
- Department of Pathology, University of Texas Health Science Center, San Antonio, Texas
| | - Hui Geng
- Department of Pathology, University of Texas Health Science Center, San Antonio, Texas
| | - Prajjal K Singha
- Department of Pathology, University of Texas Health Science Center, San Antonio, Texas
| | - Pothana Saikumar
- Department of Pathology, University of Texas Health Science Center, San Antonio, Texas
| | - Erwin P Bottinger
- Department of Medicine, Mount Sinai School of Medicine, New York, New York; and
| | - Joel M Weinberg
- Department of Medicine, Veterans Affairs Ann Arbor Healthcare System and University of Michigan Medical Center, Ann Arbor, Michigan
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932
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Wahl P, Ducasa GM, Fornoni A. Systemic and renal lipids in kidney disease development and progression. Am J Physiol Renal Physiol 2016; 310:F433-45. [PMID: 26697982 PMCID: PMC4971889 DOI: 10.1152/ajprenal.00375.2015] [Citation(s) in RCA: 84] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2015] [Accepted: 12/22/2015] [Indexed: 12/14/2022] Open
Abstract
Altered lipid metabolism characterizes proteinuria and chronic kidney diseases. While it is thought that dyslipidemia is a consequence of kidney disease, a large body of clinical and experimental studies support that altered lipid metabolism may contribute to the pathogenesis and progression of kidney disease. In fact, accumulation of renal lipids has been observed in several conditions of genetic and nongenetic origins, linking local fat to the pathogenesis of kidney disease. Statins, which target cholesterol synthesis, have not been proven beneficial to slow the progression of chronic kidney disease. Therefore, other therapeutic strategies to reduce cholesterol accumulation in peripheral organs, such as the kidney, warrant further investigation. Recent advances in the understanding of the biology of high-density lipoprotein (HDL) have revealed that functional HDL, rather than total HDL per se, may protect from both cardiovascular and kidney diseases, strongly supporting a role for altered cholesterol efflux in the pathogenesis of kidney disease. Although the underlying pathophysiological mechanisms responsible for lipid-induced renal damage have yet to be uncovered, several studies suggest novel mechanisms by which cholesterol, free fatty acids, and sphingolipids may affect glomerular and tubular cell function. This review will focus on the clinical and experimental evidence supporting a causative role of lipids in the pathogenesis of proteinuria and kidney disease, with a primary focus on podocytes.
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Affiliation(s)
- Patricia Wahl
- Peggy and Harold Katz Family Drug Discovery Center and Division of Nephrology and Hypertension, University of Miami Miller School of Medicine, Miami, Florida
| | - Gloria Michelle Ducasa
- Peggy and Harold Katz Family Drug Discovery Center and Division of Nephrology and Hypertension, University of Miami Miller School of Medicine, Miami, Florida
| | - Alessia Fornoni
- Peggy and Harold Katz Family Drug Discovery Center and Division of Nephrology and Hypertension, University of Miami Miller School of Medicine, Miami, Florida
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933
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Menezes LF, Lin CC, Zhou F, Germino GG. Fatty Acid Oxidation is Impaired in An Orthologous Mouse Model of Autosomal Dominant Polycystic Kidney Disease. EBioMedicine 2016; 5:183-92. [PMID: 27077126 PMCID: PMC4816756 DOI: 10.1016/j.ebiom.2016.01.027] [Citation(s) in RCA: 116] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2015] [Revised: 01/20/2016] [Accepted: 01/22/2016] [Indexed: 01/02/2023] Open
Abstract
BACKGROUND The major gene mutated in autosomal dominant polycystic kidney disease was first identified over 20 years ago, yet its function remains poorly understood. We have used a systems-based approach to examine the effects of acquired loss of Pkd1 in adult mouse kidney as it transitions from normal to cystic state. METHODS We performed transcriptional profiling of a large set of male and female kidneys, along with metabolomics and lipidomics analyses of a subset of male kidneys. We also assessed the effects of a modest diet change on cyst progression in young cystic mice. Fatty acid oxidation and glycolytic rates were measured in five control and mutant pairs of epithelial cells. RESULTS We find that females have a significantly less severe kidney phenotype and correlate this protection with differences in lipid metabolism. We show that sex is a major determinant of the transcriptional profile of mouse kidneys and that some of this difference is due to genes involved in lipid metabolism. Pkd1 mutant mice have transcriptional profiles consistent with changes in lipid metabolism and distinct metabolite and complex lipid profiles in kidneys. We also show that cells lacking Pkd1 have an intrinsic fatty acid oxidation defect and that manipulation of lipid content of mouse chow modifies cystic disease. INTERPRETATION Our results suggest PKD could be a disease of altered cellular metabolism.
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Affiliation(s)
- Luis F Menezes
- National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, MD, USA
| | - Cheng-Chao Lin
- National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, MD, USA
| | - Fang Zhou
- National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, MD, USA
| | - Gregory G Germino
- National Institute of Diabetes and Digestive and Kidney Disease, National Institutes of Health, Bethesda, MD, USA
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934
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Aliou Y, Liao MC, Zhao XP, Chang SY, Chenier I, Ingelfinger JR, Zhang SL. Post-weaning high-fat diet accelerates kidney injury, but not hypertension programmed by maternal diabetes. Pediatr Res 2016; 79:416-24. [PMID: 26571223 DOI: 10.1038/pr.2015.236] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/10/2015] [Accepted: 08/24/2015] [Indexed: 12/31/2022]
Abstract
BACKGROUND The aim of this study was to establish the underlying mechanisms by which a post-weaning high-fat diet (HFD) accelerates the perinatal programming of kidney injury occurring in the offspring of diabetic mothers. METHODS Male mice, offspring of nondiabetic and diabetic dams were fed with normal diet (ND) or HFD from 4 to 20 wk of age. Rat renal proximal tubular cells were used in vitro. RESULTS On ND, the offspring of dams with severe maternal diabetes had an intrauterine growth restriction (IUGR) phenotype and developed mild hypertension and evidence of kidney injury in adulthood. Exposing the IUGR offspring to HFD resulted in rapid weight gain, catch-up growth, and later to profound kidney injury with activation of renal TGFβ1 and collagen type IV expression, increased oxidative stress, and enhanced renal lipid deposition, but not systemic hypertension. Given our data, we speculate that HFD or free fatty acids may accelerate the process of perinatal programming of kidney injury, via increased CD36 and fatty acid-binding protein 4 expression, which may target reactive oxygen species, nuclear factor-kappa B, and TGFβ1 signaling in vivo and in vitro. CONCLUSION Early postnatal exposure to overnutrition with a HFD increases the risk of development of kidney injury, but not hypertension, in IUGR offspring of dams with maternal diabetes.
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Affiliation(s)
- Yessoufou Aliou
- Centre de recherche du Centre hospitalier de l'Universite de Montreal (CRCHUM), Universite de Montreal, Montréal, Quebec, Canada
| | - Min-Chun Liao
- Centre de recherche du Centre hospitalier de l'Universite de Montreal (CRCHUM), Universite de Montreal, Montréal, Quebec, Canada
| | - Xin-Ping Zhao
- Centre de recherche du Centre hospitalier de l'Universite de Montreal (CRCHUM), Universite de Montreal, Montréal, Quebec, Canada
| | - Shiao-Ying Chang
- Centre de recherche du Centre hospitalier de l'Universite de Montreal (CRCHUM), Universite de Montreal, Montréal, Quebec, Canada
| | - Isabelle Chenier
- Centre de recherche du Centre hospitalier de l'Universite de Montreal (CRCHUM), Universite de Montreal, Montréal, Quebec, Canada
| | - Julie R Ingelfinger
- Pediatric Nephrology Unit, Massachusetts General Hospital and Harvard Medical School Boston, Boston, Massachusetts
| | - Shao-Ling Zhang
- Centre de recherche du Centre hospitalier de l'Universite de Montreal (CRCHUM), Universite de Montreal, Montréal, Quebec, Canada
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935
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Li SY, Susztak K. Fat Burning Problem in Cystic Kidneys: an Emerging Common Mechanism of Chronic Kidney Disease. EBioMedicine 2016; 5:22-3. [PMID: 27077105 PMCID: PMC4816831 DOI: 10.1016/j.ebiom.2016.02.035] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022] Open
Affiliation(s)
- Szu Yuan Li
- Renal-Electrolyte and Hypertension Division, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, 415 Curie Blvd, Philadelphia, PA 19104, USA; Division of Nephrology, Department of Medicine, Taipei Veterans General Hospital and School of Medicine, National Yang-Ming University, Taipei, Taiwan
| | - Katalin Susztak
- Renal-Electrolyte and Hypertension Division, Department of Medicine, Perelman School of Medicine, University of Pennsylvania, 415 Curie Blvd, Philadelphia, PA 19104, USA
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936
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Interstitial renal fibrosis due to multiple cisplatin treatments is ameliorated by semicarbazide-sensitive amine oxidase inhibition. Kidney Int 2016; 89:374-85. [DOI: 10.1038/ki.2015.327] [Citation(s) in RCA: 51] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/01/2015] [Revised: 08/31/2015] [Accepted: 09/03/2015] [Indexed: 02/07/2023]
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937
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Venner JM, Famulski KS, Reeve J, Chang J, Halloran PF. Relationships among injury, fibrosis, and time in human kidney transplants. JCI Insight 2016; 1:e85323. [PMID: 27699214 DOI: 10.1172/jci.insight.85323] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
BACKGROUND Kidney transplant biopsies offer an opportunity to understand the pathogenesis of organ fibrosis. We studied the relationships between the time of biopsy after transplant (TxBx), histologic fibrosis, diseases, and transcript expression. METHODS Expression microarrays from 681 kidney transplant indication biopsies taken either early (n = 282, <1 year) or late (n = 399, >1 year) after transplant were used to analyze the molecular landscape of fibrosis in relationship to histologic fibrosis and diseases. RESULTS Fibrosis was absent at transplantation but was present in some early biopsies by 4 months after transplant, apparently as a self-limited response to donation implantation injury not associated with progression to failure. The molecular phenotype of early biopsies represented the time sequence of the response to wounding: immediate expression of acute kidney injury transcripts, followed by fibrillar collagen transcripts after several weeks, then by the appearance of immunoglobulin and mast cell transcripts after several months as fibrosis appeared. Fibrosis in late biopsies correlated with injury, fibrillar collagen, immunoglobulin, and mast cell transcripts, but these were independent of time. Pathway analysis revealed epithelial response-to-wounding pathways such as Wnt/β-catenin. CONCLUSION Fibrosis in late biopsies had different associations because many kidneys had potentially progressive diseases and subsequently failed. Molecular correlations with fibrosis in late biopsies were independent of time, probably because ongoing injury obscured the response-to-wounding time sequence. The results indicate that fibrosis in kidney transplants is driven by nephron injury and that progression to failure reflects continuing injury, not autonomous fibrogenesis. TRIAL REGISTRATION INTERCOM study (www.clinicalTrials.gov; NCT01299168). FUNDING Canada Foundation for Innovation and Genome Canada.
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Affiliation(s)
- Jeffery M Venner
- Alberta Transplant Applied Genomics Centre, Edmonton, Alberta, Canada.,Department of Medicine, Division of Nephrology and Transplant Immunology, Edmonton, Alberta, Canada
| | - Konrad S Famulski
- Alberta Transplant Applied Genomics Centre, Edmonton, Alberta, Canada.,Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada
| | - Jeff Reeve
- Alberta Transplant Applied Genomics Centre, Edmonton, Alberta, Canada.,Department of Laboratory Medicine and Pathology, University of Alberta, Edmonton, Alberta, Canada
| | - Jessica Chang
- Alberta Transplant Applied Genomics Centre, Edmonton, Alberta, Canada
| | - Philip F Halloran
- Alberta Transplant Applied Genomics Centre, Edmonton, Alberta, Canada.,Department of Medicine, Division of Nephrology and Transplant Immunology, Edmonton, Alberta, Canada
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938
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Kang HM, Huang S, Reidy K, Han SH, Chinga F, Susztak K. Sox9-Positive Progenitor Cells Play a Key Role in Renal Tubule Epithelial Regeneration in Mice. Cell Rep 2016; 14:861-871. [PMID: 26776520 DOI: 10.1016/j.celrep.2015.12.071] [Citation(s) in RCA: 129] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2015] [Revised: 10/02/2015] [Accepted: 12/14/2015] [Indexed: 01/01/2023] Open
Abstract
The kidney has a tremendous capacity to regenerate following injury, but factors that govern this response are still largely unknown. We isolated cells from mouse kidneys with high proliferative and multi-lineage differentiation capacity. These cells expressed a high level of Sox9. In regenerating kidneys, Sox9 expression was induced early, and 89% of proliferating cells were Sox9 positive. In vitro, Sox9-positive cells showed unlimited proliferation and multi-lineage differentiation capacity. Using an inducible Sox9 Cre line and lineage-tagging methods, we show that Sox9-positive cells can generate new daughter cells, contributing to the regeneration of proximal tubule, loop of Henle, and distal tubule segments but not to collecting duct and glomerular cells. Furthermore, inducible deletion of Sox9 resulted in reduced epithelial proliferation, more severe injury, and fibrosis development. In summary, we demonstrate that, in the kidney, Sox9-positive cells show progenitor-like properties in vitro and contribute to epithelial regeneration following injury in vivo.
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Affiliation(s)
- Hyun Mi Kang
- Renal Electrolyte and Hypertension Division, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Shizheng Huang
- Renal Electrolyte and Hypertension Division, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Kimberly Reidy
- Renal Electrolyte and Hypertension Division, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Seung Hyeok Han
- Renal Electrolyte and Hypertension Division, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Frank Chinga
- Renal Electrolyte and Hypertension Division, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Katalin Susztak
- Renal Electrolyte and Hypertension Division, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA 19104, USA.
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939
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Abstract
Acute kidney injury (AKI) continues to be a significant contributor to morbidity, mortality, and health care expenditure. In the United States alone, it is estimated that more than $10 billion is spent on AKI every year. Currently, there are no available therapies to treat established AKI. The mitochondrion is positioned to be a critical player in AKI with its dual role as the primary source of energy for each cell and as a key regulator of cell death. This review aims to cover the current state of research on the role of mitochondria in AKI, while also proposing potential therapeutic targets and future therapies.
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Affiliation(s)
- Kenneth M Ralto
- Division of Nephrology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA
| | - Samir M Parikh
- Division of Nephrology, Beth Israel Deaconess Medical Center and Harvard Medical School, Boston, MA.
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940
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941
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Dominguez JH, Liu Y, Kelly KJ. Renal iron overload in rats with diabetic nephropathy. Physiol Rep 2015; 3:3/12/e12654. [PMID: 26702071 PMCID: PMC4760458 DOI: 10.14814/phy2.12654] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2015] [Accepted: 11/16/2015] [Indexed: 12/27/2022] Open
Abstract
Diabetic nephropathy (DN) remains incurable and is the main cause of end-stage renal disease. We approached the pathophysiology of DN with systems biology, and a comprehensive profile of renal transcripts was obtained with RNA-Seq in ZS (F1 hybrids of Zucker and spontaneously hypertensive heart failure) rats, a model of diabetic nephropathy. We included sham-operated lean control rats (LS), sham-operated diabetic (DS), and diabetic rats with induced renal ischemia (DI). Diabetic nephropathy in DI was accelerated by the single episode of renal ischemia. This progressive renal decline was associated with renal iron accumulation, although serum and urinary iron levels were far lower in DI than in LS. Furthermore, obese/diabetic ZS rats have severe dyslipidemia, a condition that has been linked to hepatic iron overload. Hence, we tested and found that the fatty acids oleic acid and palmitate stimulated iron accumulation in renal tubular cells in vitro. Renal mRNAs encoding several key proteins that promote iron accumulation were increased in DI. Moreover, renal mRNAs encoding the antioxidant proteins superoxide dismutase, catalase, and most of the glutathione synthetic system were suppressed, which would magnify the prooxidant effects of renal iron loads. Substantial renal iron loads occur in obese/diabetic rats. We propose that in diabetes, specific renal gene activation is partly responsible for iron accumulation. This state might be further aggravated by lipid-stimulated iron uptake. We suggest that progressive renal iron overload may further advance renal injury in obese/diabetic ZS rats.
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Affiliation(s)
- Jesus H Dominguez
- Departments of Medicine, Indiana University School of Medicine, Indianapolis, Indiana Roudebush Veterans' Affairs Medical Center, Indianapolis, Indiana
| | - Yunlong Liu
- Medical and Molecular Genetics, Indiana University School of Medicine, Indianapolis, Indiana
| | - Katherine J Kelly
- Departments of Medicine, Indiana University School of Medicine, Indianapolis, Indiana
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942
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Obesity-Related Chronic Kidney Disease-The Role of Lipid Metabolism. Metabolites 2015; 5:720-32. [PMID: 26690487 PMCID: PMC4693192 DOI: 10.3390/metabo5040720] [Citation(s) in RCA: 49] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2015] [Revised: 12/01/2015] [Accepted: 12/08/2015] [Indexed: 02/06/2023] Open
Abstract
Obesity is an independent risk factor for chronic kidney disease (CKD). The mechanisms linking obesity and CKD include systemic changes such as high blood pressure and hyperglycemia, and intrarenal effects relating to lipid accumulation. Normal lipid metabolism is integral to renal physiology and disturbances of renal lipid and energy metabolism are increasingly being linked with kidney disease. AMP-activated protein kinase (AMPK) and acetyl-CoA carboxylase (ACC) are important regulators of fatty acid oxidation, which is frequently abnormal in the kidney with CKD. A high fat diet reduces renal AMPK activity, thereby contributing to reduced fatty acid oxidation and energy imbalance, and treatments to activate AMPK are beneficial in animal models of obesity-related CKD. Studies have found that the specific cell types affected by excessive lipid accumulation are proximal tubular cells, podocytes, and mesangial cells. Targeting disturbances of renal energy metabolism is a promising approach to addressing the current epidemic of obesity-related kidney disease.
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943
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Gai Z, Gui T, Hiller C, Kullak-Ublick GA. Farnesoid X Receptor Protects against Kidney Injury in Uninephrectomized Obese Mice. J Biol Chem 2015; 291:2397-411. [PMID: 26655953 DOI: 10.1074/jbc.m115.694323] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2015] [Indexed: 01/07/2023] Open
Abstract
Activation of the farnesoid X receptor (FXR) has indicated a therapeutic potential for this nuclear bile acid receptor in the prevention of diabetic nephropathy and obesity-induced renal damage. Here, we investigated the protective role of FXR against kidney damage induced by obesity in mice that had undergone uninephrectomy, a model resembling the clinical situation of kidney donation by obese individuals. Mice fed a high-fat diet developed the core features of metabolic syndrome, with subsequent renal lipid accumulation and renal injury, including glomerulosclerosis, interstitial fibrosis, and albuminuria. The effects were accentuated by uninephrectomy. In human renal biopsies, staining of 4-hydroxynonenal (4-HNE), glucose-regulated protein 78 (Grp78), and C/EBP-homologous protein, markers of endoplasmic reticulum stress, was more prominent in the proximal tubules of 15 obese patients compared with 16 non-obese patients. In mice treated with the FXR agonist obeticholic acid, renal injury, renal lipid accumulation, apoptosis, and changes in lipid peroxidation were attenuated. Moreover, disturbed mitochondrial function was ameliorated and the mitochondrial respiratory chain recovered following obeticholic acid treatment. Culturing renal proximal tubular cells with free fatty acid and FXR agonists showed that FXR activation protected cells from free fatty acid-induced oxidative stress and endoplasmic reticulum stress, as denoted by a reduction in the level of reactive oxygen species staining and Grp78 immunostaining, respectively. Several genes involved in glutathione metabolism were induced by FXR activation in the remnant kidney, which was consistent with a decreased glutathione disulfide/glutathione ratio. In summary, FXR activation maintains endogenous glutathione homeostasis and protects the kidney in uninephrectomized mice from obesity-induced injury.
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Affiliation(s)
- Zhibo Gai
- From the Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, University of Zurich, CH-8091 Zurich, Switzerland and
| | - Ting Gui
- the Department of Nephrology, Hypertension, and Clinical Pharmacology, Inselspital, CH-3010 Bern, Switzerland
| | - Christian Hiller
- From the Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, University of Zurich, CH-8091 Zurich, Switzerland and
| | - Gerd A Kullak-Ublick
- From the Department of Clinical Pharmacology and Toxicology, University Hospital Zurich, University of Zurich, CH-8091 Zurich, Switzerland and
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944
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Abstract
Despite marked improvements in the survival of patients with severe lupus nephritis over the past 50 years, the rate of complete clinical remission after immune suppression therapy is <50% and renal impairment still occurs in 40% of affected patients. An appreciation of the factors that lead to the development of chronic kidney disease following acute or subacute renal injury in patients with systemic lupus erythematosus is beginning to emerge. Processes that contribute to end-stage renal injury include continuing inflammation, activation of intrinsic renal cells, cell stress and hypoxia, metabolic abnormalities, aberrant tissue repair and tissue fibrosis. A deeper understanding of these processes is leading to the development of novel or adjunctive therapies that could protect the kidney from the secondary non-immune consequences of acute injury. Approaches based on a molecular-proteomic-lipidomic classification of disease should yield new information about the functional basis of disease heterogeneity so that the most effective and least toxic treatment regimens can be formulated for individual patients.
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945
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Houten SM, Violante S, Ventura FV, Wanders RJA. The Biochemistry and Physiology of Mitochondrial Fatty Acid β-Oxidation and Its Genetic Disorders. Annu Rev Physiol 2015; 78:23-44. [PMID: 26474213 DOI: 10.1146/annurev-physiol-021115-105045] [Citation(s) in RCA: 465] [Impact Index Per Article: 51.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Mitochondrial fatty acid β-oxidation (FAO) is the major pathway for the degradation of fatty acids and is essential for maintaining energy homeostasis in the human body. Fatty acids are a crucial energy source in the postabsorptive and fasted states when glucose supply is limiting. But even when glucose is abundantly available, FAO is a main energy source for the heart, skeletal muscle, and kidney. A series of enzymes, transporters, and other facilitating proteins are involved in FAO. Recessively inherited defects are known for most of the genes encoding these proteins. The clinical presentation of these disorders may include hypoketotic hypoglycemia, (cardio)myopathy, arrhythmia, and rhabdomyolysis and illustrates the importance of FAO during fasting and in hepatic and (cardio)muscular function. In this review, we present the current state of knowledge on the biochemistry and physiological functions of FAO and discuss the pathophysiological processes associated with FAO disorders.
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Affiliation(s)
- Sander M Houten
- Department of Genetics and Genomic Sciences and Icahn Institute for Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029; ,
| | - Sara Violante
- Department of Genetics and Genomic Sciences and Icahn Institute for Genomics and Multiscale Biology, Icahn School of Medicine at Mount Sinai, New York, NY 10029; ,
| | - Fatima V Ventura
- Metabolism and Genetics Group, Research Institute for Medicines and Pharmaceutical Sciences, iMed.ULisboa, 1649-003 Lisboa, Portugal; .,Department of Biochemistry and Human Biology, Faculty of Pharmacy, University of Lisbon, 1649-003 Lisboa, Portugal
| | - Ronald J A Wanders
- Laboratory Genetic Metabolic Diseases, Department of Clinical Chemistry, University of Amsterdam, 1100 DE Amsterdam, The Netherlands; .,Department of Pediatrics, Emma Children's Hospital, Academic Medical Center, University of Amsterdam, 1105 AZ Amsterdam, The Netherlands
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946
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Mount PF, Power DA. Balancing the energy equation for healthy kidneys. J Pathol 2015; 237:407-10. [PMID: 26296948 DOI: 10.1002/path.4600] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2015] [Revised: 08/06/2015] [Accepted: 08/12/2015] [Indexed: 01/18/2023]
Abstract
The high-energy requirement of the kidney and the importance of energy metabolism in renal physiology has been appreciated for decades, but only recently has there emerged a strong link between impaired renal energy metabolism and chronic kidney disease (CKD). The mechanisms underlying the association between changes in energy metabolism and progression of CKD, however, remain poorly understood. A new study from Qiu and colleagues reported in the Journal of Pathology has advanced this understanding by showing that, after renal injury, the energy sensor AMPK inhibits epithelial-mesenchymal transition and inflammation, processes important in the pathogenesis of CKD. Furthermore, this study identifies an interaction between AMPK and CK2β as an important mechanism in the anti-fibrotic effect. CK2β has previously been shown to interact with STK11 (also known as LKB1) to regulate cellular polarity. These findings are consistent with the known roles of the LKB1-AMPK pathway in sustaining cellular energy homeostasis and epithelial cell polarity, and add to growing evidence linking the suppression of energy metabolism to CKD. They emphasize the importance of energy metabolism in general and the LKB1-AMPK axis in particular as key investigational and therapeutic targets in the battle against CKD.
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Affiliation(s)
- Peter F Mount
- Department of Nephrology, Austin Health, Heidelberg, Melbourne, Australia.,Department of Medicine, University of Melbourne, Parkville, Melbourne, Australia.,Institute for Breathing and Sleep, Austin Health, Heidelberg, Melbourne, Australia
| | - David A Power
- Department of Nephrology, Austin Health, Heidelberg, Melbourne, Australia.,Department of Medicine, University of Melbourne, Parkville, Melbourne, Australia.,Institute for Breathing and Sleep, Austin Health, Heidelberg, Melbourne, Australia
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947
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Zhao YY, Wang HL, Cheng XL, Wei F, Bai X, Lin RC, Vaziri ND. Metabolomics analysis reveals the association between lipid abnormalities and oxidative stress, inflammation, fibrosis, and Nrf2 dysfunction in aristolochic acid-induced nephropathy. Sci Rep 2015; 5:12936. [PMID: 26251179 PMCID: PMC4528220 DOI: 10.1038/srep12936] [Citation(s) in RCA: 133] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2015] [Accepted: 07/13/2015] [Indexed: 12/31/2022] Open
Abstract
Alternative medicines are commonly used for the disease prevention and treatment worldwide. Aristolochic acid (AAI) nephropathy (AAN) is a common and rapidly progressive interstitial nephropathy caused by ingestion of Aristolochia herbal medications. Available data on pathophysiology and molecular mechanisms of AAN are limited and were explored here. SD rats were randomized to AAN and control groups. AAN group was treated with AAI by oral gavage for 12 weeks and observed for additional 12 weeks. Kidneys were processed for histological evaluation, Western blotting, and metabolomics analyses using UPLC-QTOF/HDMS. The concentrations of two phosphatidylcholines, two diglycerides and two acyl-carnitines were significantly altered in AAI treated rats at week 4 when renal function and histology were unchanged. Data obtained on weeks 8 to 24 revealed progressive tubulointerstitial fibrosis, inflammation, renal dysfunction, activation of NF-κB, TGF-β, and oxidative pathways, impaired Nrf2 system, and profound changes in lipid metabolites including numerous PC, lysoPC, PE, lysoPE, ceramides and triglycerides. In conclusion, exposure to AAI results in dynamic changes in kidney tissue fatty acid, phospholipid, and glycerolipid metabolisms prior to and after the onset of detectable changes in renal function or histology. These findings point to participation of altered tissue lipid metabolism in the pathogenesis of AAN.
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Affiliation(s)
- Ying-Yong Zhao
- 1] Key Laboratory of Resource Biology and Biotechnology in Western China, Ministry of Education, the College of Life Sciences, Northwest University, No. 229 Taibai North Road, Xi'an, Shaanxi 710069, China [2] Division of Nephrology and Hypertension, School of Medicine, University of California, Irvine, MedSci 1, C352, UCI Campus, Irvine, California, 92897, USA
| | - Hui-Ling Wang
- Department of nephrology, Shanghai Jimin Hospital, No. 338 Huaihai West Road, Shanghai 200052, China
| | - Xian-Long Cheng
- National Institutes for Food and Drug Control, State Food and Drug Administration, No. 2 Tiantan Xili, Beijing, 100050, China
| | - Feng Wei
- National Institutes for Food and Drug Control, State Food and Drug Administration, No. 2 Tiantan Xili, Beijing, 100050, China
| | - Xu Bai
- Solution Centre, Waters Technologies (Shanghai) Ltd., No. 1000 Jinhai Road, Shanghai 201203, China
| | - Rui-Chao Lin
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, No. 11 North Third Ring Road, Beijing 100029, China
| | - Nosratola D Vaziri
- Division of Nephrology and Hypertension, School of Medicine, University of California, Irvine, MedSci 1, C352, UCI Campus, Irvine, California, 92897, USA
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948
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Simon N, Hertig A. Alteration of Fatty Acid Oxidation in Tubular Epithelial Cells: From Acute Kidney Injury to Renal Fibrogenesis. Front Med (Lausanne) 2015; 2:52. [PMID: 26301223 PMCID: PMC4525064 DOI: 10.3389/fmed.2015.00052] [Citation(s) in RCA: 110] [Impact Index Per Article: 12.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2015] [Accepted: 07/17/2015] [Indexed: 12/11/2022] Open
Abstract
Renal proximal tubular cells are the most energy-demanding cells in the body. The ATP that they use is mostly produced in their mitochondrial and peroxisomal compartments, by the oxidation of fatty acids. When those cells are placed under a biological stress, such as a transient hypoxia, fatty acid oxidation (FAO) is shut down for a period of time that outlasts injury, and carbohydrate oxidation does not take over. Facing those metabolic constraints, surviving tubular epithelial cells exhibit a phenotypic switch that includes cytoskeletal rearrangement and production of extracellular matrix proteins, most probably contributing to acute kidney injury-induced renal fibrogenesis, thence to the development of chronic kidney disease. Here, we review experimental evidence that dysregulation of FAO profoundly affects the fate of tubular epithelial cells, by promoting epithelial-to-mesenchymal transition, inflammation, and eventually interstitial fibrosis. Restoring physiological production of energy is undoubtedly a possible therapeutic approach to unlock the mesenchymal reprograming of tubular epithelial cells in the kidney. In this respect, the benefit of the use of fibrates is uncertain, but new drugs that could specifically target this metabolic pathway, and, hopefully, attenuate renal fibrosis merit future research.
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Affiliation(s)
- Noémie Simon
- IMSERM UMR_S1155, Rare and Common Kidney Diseases, Remodeling and Tissue Repair, Hôpital Tenon , Paris , France
| | - Alexandre Hertig
- IMSERM UMR_S1155, Rare and Common Kidney Diseases, Remodeling and Tissue Repair, Hôpital Tenon , Paris , France ; UMR S 1155, UPMC Sorbonne Université Paris 06 , Paris , France
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949
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Lovisa S, LeBleu VS, Tampe B, Sugimoto H, Vadnagara K, Carstens JL, Wu CC, Hagos Y, Burckhardt BC, Pentcheva-Hoang T, Nischal H, Allison JP, Zeisberg M, Kalluri R. Epithelial-to-mesenchymal transition induces cell cycle arrest and parenchymal damage in renal fibrosis. Nat Med 2015; 21:998-1009. [PMID: 26236991 PMCID: PMC4587560 DOI: 10.1038/nm.3902] [Citation(s) in RCA: 679] [Impact Index Per Article: 75.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2015] [Accepted: 06/15/2015] [Indexed: 02/06/2023]
Abstract
Kidney fibrosis is marked by an epithelial–to–mesenchymal transition (EMT) by tubular epithelial cells (TECs). Here we find that during renal fibrosis TECs acquire a partial EMT program during which they remain associated with their basement membrane and express markers of both epithelial and mesenchymal cells. The functional consequence of EMT program during fibrotic injury is an arrest in the G2 phase of the cell cycle and lower expression of several transporters in TECs. We also found that transgenic expression of Twist or Snai1 expression is sufficient to promote prolonged TGF-β1–induced G2 arrest of TECs, limiting their potential for repair and regeneration. Also, in mouse models of experimentally-induced renal fibrosis, conditional deletion of Twist1 or Snai1 in proximal TECs resulted in inhibition of the EMT program and the maintenance of TEC integrity, while restoring proliferation, de–differentiation–associated repair and regeneration of the kidney parenchyma and attenuating interstitial fibrosis. Thus, inhibition of EMT program in TECs during chronic renal injury represents a potential anti–fibrosis therapy
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Affiliation(s)
- Sara Lovisa
- Department of Cancer Biology, Metastasis Research Center, University of Texas M.D. Anderson Cancer Center, Houston, Texas, USA
| | - Valerie S LeBleu
- Department of Cancer Biology, Metastasis Research Center, University of Texas M.D. Anderson Cancer Center, Houston, Texas, USA
| | - Björn Tampe
- Department of Nephrology and Rheumatology, Göttingen University Medical Center, Georg August University, Göttingen, Germany
| | - Hikaru Sugimoto
- Department of Cancer Biology, Metastasis Research Center, University of Texas M.D. Anderson Cancer Center, Houston, Texas, USA
| | - Komal Vadnagara
- Department of Cancer Biology, Metastasis Research Center, University of Texas M.D. Anderson Cancer Center, Houston, Texas, USA
| | - Julienne L Carstens
- Department of Cancer Biology, Metastasis Research Center, University of Texas M.D. Anderson Cancer Center, Houston, Texas, USA
| | - Chia-Chin Wu
- Department of Genomic Medicine, University of Texas M.D. Anderson Cancer Center, Houston, Texas, USA
| | - Yohannes Hagos
- Institute of Systemic Physiology and Pathophysiology, Göttingen University Medical Center, Georg August University, Göttingen, Germany
| | - Birgitta C Burckhardt
- Institute of Systemic Physiology and Pathophysiology, Göttingen University Medical Center, Georg August University, Göttingen, Germany
| | | | - Hersharan Nischal
- Department of Immunology, University of Texas M.D. Anderson Cancer Center, Houston, Texas, USA
| | - James P Allison
- Department of Immunology, University of Texas M.D. Anderson Cancer Center, Houston, Texas, USA
| | - Michael Zeisberg
- Department of Nephrology and Rheumatology, Göttingen University Medical Center, Georg August University, Göttingen, Germany
| | - Raghu Kalluri
- Department of Cancer Biology, Metastasis Research Center, University of Texas M.D. Anderson Cancer Center, Houston, Texas, USA
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950
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Venkatachalam MA, Weinberg JM, Kriz W, Bidani AK. Failed Tubule Recovery, AKI-CKD Transition, and Kidney Disease Progression. J Am Soc Nephrol 2015; 26:1765-76. [PMID: 25810494 PMCID: PMC4520181 DOI: 10.1681/asn.2015010006] [Citation(s) in RCA: 480] [Impact Index Per Article: 53.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
The transition of AKI to CKD has major clinical significance. As reviewed here, recent studies show that a subpopulation of dedifferentiated, proliferating tubules recovering from AKI undergo pathologic growth arrest, fail to redifferentiate, and become atrophic. These abnormal tubules exhibit persistent, unregulated, and progressively increasing profibrotic signaling along multiple pathways. Paracrine products derived therefrom perturb normal interactions between peritubular capillary endothelium and pericyte-like fibroblasts, leading to myofibroblast transformation, proliferation, and fibrosis as well as capillary disintegration and rarefaction. Although signals from injured endothelium and inflammatory/immune cells also contribute, tubule injury alone is sufficient to produce the interstitial pathology required for fibrosis. Localized hypoxia produced by microvascular pathology may also prevent tubule recovery. However, fibrosis is not intrinsically progressive, and microvascular pathology develops strictly around damaged tubules; thus, additional deterioration of kidney structure after the transition of AKI to CKD requires new acute injury or other mechanisms of progression. Indeed, experiments using an acute-on-chronic injury model suggest that additional loss of parenchyma caused by failed repair of AKI in kidneys with prior renal mass reduction triggers hemodynamically mediated processes that damage glomeruli to cause progression. Continued investigation of these pathologic mechanisms should reveal options for preventing renal disease progression after AKI.
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Affiliation(s)
| | - Joel M Weinberg
- Department of Medicine, Veterans Affairs Ann Arbor Healthcare System and University of Michigan Medical Center, Ann Arbor, Michigan
| | - Wilhelm Kriz
- Medical Fakultät Mannheim, Abteilung Anatomie und Entwicklungsbiologie Mannheim, University of Heidelberg, Baden-Wuerttemberg, Germany; and
| | - Anil K Bidani
- Department of Medicine, Loyola University and Hines Veterans Affairs Hospital, Maywood, Illinois
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