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Wang ZH, Dong Q, Yan Q, Yu WR, Zhang DD, Yi R. Constructing the biomolecular networks associated with diabetic nephropathy and dissecting the effects of biomolecule variation underlying pathogenesis. Endocr J 2024; 71:1031-1043. [PMID: 39069497 PMCID: PMC11778351 DOI: 10.1507/endocrj.ej24-0170] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/25/2024] [Accepted: 06/05/2024] [Indexed: 07/30/2024] Open
Abstract
Diabetic nephropathy (DN) is a common and serious complication of diabetes, contributing significantly to patient mortality. Complication of DN (CDN) ranks as the second leading cause of end-stage renal disease globally. To address this, understanding the genetic regulation underlying DN is crucial for personalized treatment strategies. In this study, we identified genes and lncRNAs associated with diabetes and diabetic nephropathy constructing a DN-related lncRNA-mRNA network (DNLMN). This network, characterized by scale-free biomolecular properties, generated through the study of topological properties, elucidates key regulatory interactions. Enrichment analysis of important network modules revealed critical biological processes and pathways involved in DN pathogenesis. In the second step, we investigated the differential expression and co-expression of hub nodes in diseased and normal individuals, identifying lncRNA-mRNA relationships implicated in disease regulation. Finally, we gathered DN-related single nucleotide polymorphisms (SNPs) and lncRNAs from the LincSNP 3.0 database. The DNLMN encompasses SNP-associated lncRNAs, and transcription factors (TFs) linked to differentially expressed lncRNAs between diseased and normal samples. These results underscore the significance of biomolecular networks in disease progression and highlighting the role of biomolecular variability contributes to personalized disease phenotyping and treatment.
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Affiliation(s)
- Zi-Han Wang
- Department of Endocrine, the First Affiliated Hospital of Harbin Medical University, Harbin 150001, People’s Republic of China
| | - Qi Dong
- Department of Neurology, the First Affiliated Hospital of Harbin Medical University, Harbin 150001, People’s Republic of China
| | - Qian Yan
- Department of Endocrine, the First Affiliated Hospital of Harbin Medical University, Harbin 150001, People’s Republic of China
| | - Wan-Rong Yu
- Department of Endocrine, the First Affiliated Hospital of Harbin Medical University, Harbin 150001, People’s Republic of China
| | - Dan-Dan Zhang
- Department of Endocrine, the First Affiliated Hospital of Harbin Medical University, Harbin 150001, People’s Republic of China
| | - Ran Yi
- Department of Endocrine, the First Affiliated Hospital of Harbin Medical University, Harbin 150001, People’s Republic of China
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Zhang M, Hogstrand C, Pontrelli P, Malik AN. Co-regulation and synteny of GFM2 and NSA2 links ribosomal function in mitochondria and the cytosol with chronic kidney disease. Mol Med 2024; 30:176. [PMID: 39396937 PMCID: PMC11476648 DOI: 10.1186/s10020-024-00930-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2024] [Accepted: 09/08/2024] [Indexed: 10/15/2024] Open
Abstract
BACKGROUND We previously reported aberrant expression of the cytosolic ribosomal biogenesis factor Nop-7-associated 2 (NSA2) in diabetic nephropathy, the latter also known to involve mitochondrial dysfunction, however the connections between NSA2, mitochondria and renal disease were unclear. In the current paper, we show that NSA2 expression is co-regulated with the GTP-dependent ribosome recycling factor mitochondrial 2 (GFM2) and provide a molecular link between cytosolic and mitochondrial ribosomal biogenesis with mitochondrial dysfunction in chronic kidney disease (CKD). METHODS Human renal tubular cells (HK-2) were cultured (+/- zinc, or 5mM/20mM glucose). mRNA levels were quantified using real-time qPCR. Transcriptomics data were retrieved and analysed from Nakagawa chronic kidney disease (CKD) Dataset (GSE66494) and Kidney Precision Medicine Project (KPMP) ( https://atlas.kpmp.org/ ). Protein levels were determined by immunofluorescence and Western blotting. Cellular respiration was measured using Agilent Seahorse XF Analyzer. Data were analysed using one-way ANOVA, Students' t-test and Pearson correlation. RESULTS The NSA2 gene, on human chromosome 5q13 was next to GFM2. The two genes were syntenic on opposite strands and orientation in multiple species. Their common 381 bp 5' region contained multiple transcription factor binding sites (TFBS) including the zinc-responsive transcription factor MTF1. NSA2 and GFM2 mRNAs showed a dose-dependent increase to zinc in-vitro and were highly expressed in proximal tubular cells in renal biopsies. CKD patients showed higher renal NSA2/GFM2 expression. In HK-2 cells, hyperglycaemia led to increased expression of both genes. The total cellular protein content remained unchanged, but GFM2 upregulation resulted in increased levels of several mitochondrial oxidative phosphorylation (OXPHOS) subunits. Furthermore, increased GFM2 expression, via transient transfection or hyperglycemia, correlated with decrease cellular respiration. CONCLUSION The highly conserved synteny of NSA2 and GFM2, their shared 5' region, and co-expression in-vitro and in CKD, shows they are co-regulated. Increased GFM2 affects mitochondrial function with a disconnect between an increase in certain mitochondrial respiratory proteins but a decrease in cellular respiration. These data link the regulation of 2 highly conserved genes, NSA2 and GFM2, connected to ribosomes in two different cellular compartments, cytosol and mitochondria, to kidney disease and shows that their dysregulation may be involved in mitochondrial dysfunction.
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Affiliation(s)
- Minjie Zhang
- Diabetes & Obesity, School of Cardiovascular Medicine and Metabolic Sciences, King's College London, London, SE1 1UL, UK
| | - Christer Hogstrand
- Analytical, Environmental and Forensic Sciences, School of Cancer and Pharmaceutical Sciences, King's College London, London, SE1 8NH, UK
| | - Paola Pontrelli
- Department of Precision and Regenerative Medicine and Ionian Area (DIMEPRE-J), University of Bari Aldo Moro, Bari, Italy
| | - Afshan N Malik
- Diabetes & Obesity, School of Cardiovascular Medicine and Metabolic Sciences, King's College London, London, SE1 1UL, UK.
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Li P, Ning Y, Guo X, Wen Y, Cheng B, Ma M, Zhang L, Cheng S, Wang S, Zhang F. Integrating transcriptome-wide study and mRNA expression profiles yields novel insights into the biological mechanism of chondropathies. Arthritis Res Ther 2019; 21:194. [PMID: 31455417 PMCID: PMC6712880 DOI: 10.1186/s13075-019-1978-8] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/13/2019] [Accepted: 08/16/2019] [Indexed: 12/31/2022] Open
Abstract
Background Chondropathies are a group of cartilage diseases, which share some common pathogenetic features. The etiology of chondropathies is still largely obscure now. Methods A transcriptome-wide association study (TWAS) was performed using the UK Biobank genome-wide association study (GWAS) data of chondropathies (including 1314 chondropathy patients and 450,950 controls) with gene expression references of muscle skeleton (MS) and peripheral blood (YBL). The candidate genes identified by TWAS were further compared with three gene expression profiles of osteoarthritis (OA), cartilage tumor (CT), and spinal disc herniation (SDH), to confirm the functional relevance between the chondropathies and the candidate genes identified by TWAS. Functional mapping and annotation (FUMA) was used for the gene ontology enrichment analyses. Immunohistochemistry (IHC) was conducted to validate the accuracy of integrative analysis results. Results Integrating TWAS and mRNA expression profiles detected 84 candidate genes for knee OA, such as DDX20 (PTWAS YBL = 1.79 × 10− 3, fold change (FC) = 2.69), 10 candidate genes for CT, such as SRGN (PTWAS YBL = 1.46 × 10− 3, FC = 3.36), and 4 candidate genes for SDH, such as SUPV3L1 (PTWAS YBL = 3.59 × 10− 3, FC = 3.22). Gene set enrichment analysis detected 73 GO terms for knee OA, 3 GO terms for CT, and 1 GO term for SDH, such as mitochondrial protein complex (P = 7.31 × 10− 5) for knee OA, cytokine for CT (P = 1.13 × 10− 4), and ion binding for SDH (P = 3.55 × 10− 4). IHC confirmed that the protein expression level of DDX20 was significantly different between knee OA cartilage and healthy control cartilage (P = 0.0358). Conclusions Multiple candidate genes and GO terms were detected for chondropathies. Our findings may provide a novel insight in the molecular mechanisms of chondropathies. Electronic supplementary material The online version of this article (10.1186/s13075-019-1978-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ping Li
- Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, Key Laboratory of Environment and Genes Related to Diseases of Ministry of Education, Collaborative Innovation Center of Endemic Diseases and Health Promotion in Silk Road Region, School of Public Health, Health Science Center, Xi'an Jiaotong University, No.76 Yan Ta West Road, Xi'an, 710061, Shaanxi, People's Republic of China
| | - Yujie Ning
- Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, Key Laboratory of Environment and Genes Related to Diseases of Ministry of Education, Collaborative Innovation Center of Endemic Diseases and Health Promotion in Silk Road Region, School of Public Health, Health Science Center, Xi'an Jiaotong University, No.76 Yan Ta West Road, Xi'an, 710061, Shaanxi, People's Republic of China
| | - Xiong Guo
- Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, Key Laboratory of Environment and Genes Related to Diseases of Ministry of Education, Collaborative Innovation Center of Endemic Diseases and Health Promotion in Silk Road Region, School of Public Health, Health Science Center, Xi'an Jiaotong University, No.76 Yan Ta West Road, Xi'an, 710061, Shaanxi, People's Republic of China
| | - Yan Wen
- Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, Key Laboratory of Environment and Genes Related to Diseases of Ministry of Education, Collaborative Innovation Center of Endemic Diseases and Health Promotion in Silk Road Region, School of Public Health, Health Science Center, Xi'an Jiaotong University, No.76 Yan Ta West Road, Xi'an, 710061, Shaanxi, People's Republic of China
| | - Bolun Cheng
- Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, Key Laboratory of Environment and Genes Related to Diseases of Ministry of Education, Collaborative Innovation Center of Endemic Diseases and Health Promotion in Silk Road Region, School of Public Health, Health Science Center, Xi'an Jiaotong University, No.76 Yan Ta West Road, Xi'an, 710061, Shaanxi, People's Republic of China
| | - Mei Ma
- Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, Key Laboratory of Environment and Genes Related to Diseases of Ministry of Education, Collaborative Innovation Center of Endemic Diseases and Health Promotion in Silk Road Region, School of Public Health, Health Science Center, Xi'an Jiaotong University, No.76 Yan Ta West Road, Xi'an, 710061, Shaanxi, People's Republic of China
| | - Lu Zhang
- Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, Key Laboratory of Environment and Genes Related to Diseases of Ministry of Education, Collaborative Innovation Center of Endemic Diseases and Health Promotion in Silk Road Region, School of Public Health, Health Science Center, Xi'an Jiaotong University, No.76 Yan Ta West Road, Xi'an, 710061, Shaanxi, People's Republic of China
| | - Shiqiang Cheng
- Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, Key Laboratory of Environment and Genes Related to Diseases of Ministry of Education, Collaborative Innovation Center of Endemic Diseases and Health Promotion in Silk Road Region, School of Public Health, Health Science Center, Xi'an Jiaotong University, No.76 Yan Ta West Road, Xi'an, 710061, Shaanxi, People's Republic of China
| | - Sen Wang
- Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, Key Laboratory of Environment and Genes Related to Diseases of Ministry of Education, Collaborative Innovation Center of Endemic Diseases and Health Promotion in Silk Road Region, School of Public Health, Health Science Center, Xi'an Jiaotong University, No.76 Yan Ta West Road, Xi'an, 710061, Shaanxi, People's Republic of China
| | - Feng Zhang
- Key Laboratory of Trace Elements and Endemic Diseases of National Health and Family Planning Commission, Key Laboratory of Environment and Genes Related to Diseases of Ministry of Education, Collaborative Innovation Center of Endemic Diseases and Health Promotion in Silk Road Region, School of Public Health, Health Science Center, Xi'an Jiaotong University, No.76 Yan Ta West Road, Xi'an, 710061, Shaanxi, People's Republic of China.
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Nop-7-associated 2 (NSA2) is required for ribosome biogenesis and protein synthesis. Biochem Biophys Res Commun 2018; 505:249-254. [PMID: 30243719 DOI: 10.1016/j.bbrc.2018.09.041] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2018] [Accepted: 09/07/2018] [Indexed: 12/11/2022]
Abstract
Ribosome biogenesis is a fundamental cellular process and occurs mainly in the nucleolus in eukaryotes. The process is exceptionally complex and highly regulated by numerous ribosomal and non-ribosomal factors. A recent discovery strengthened the link between ribosome biogenesis and malignant transformation. Here, we determined that Nop-7-associated 2 (NSA2) is a nucleolar protein required for ribosome biogenesis. NSA2 knockdown reduced the rate of rRNA synthesis, diminishing the 60S ribosomal subunit. Moreover, we demonstrated that depletion of NSA2 suppressed protein synthesis. To investigate the signaling pathway affected by NSA2, NSA2 was depleted, which triggered the inactivation of the mTOR signaling pathway. Taken together, our findings reveal a novel function of NSA2 and provide insight into the regulation of ribosome biogenesis by NSA2.
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Korashy HM, Attafi IM, Famulski KS, Bakheet SA, Hafez MM, Alsaad AMS, Al-Ghadeer ARM. Gene expression profiling to identify the toxicities and potentially relevant human disease outcomes associated with environmental heavy metal exposure. ENVIRONMENTAL POLLUTION (BARKING, ESSEX : 1987) 2017; 221:64-74. [PMID: 27916491 DOI: 10.1016/j.envpol.2016.10.058] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Revised: 10/09/2016] [Accepted: 10/19/2016] [Indexed: 06/06/2023]
Abstract
Heavy metals are the most commonly encountered toxic substances that increase susceptibility to various diseases after prolonged exposure. We have previously shown that healthy volunteers living near a mining area had significant contamination with heavy metals associated with significant changes in the expression of some detoxifying genes, xenobiotic metabolizing enzymes, and DNA repair genes. However, alterations of most of the molecular target genes associated with diseases are still unknown. Thus, the aims of this study were to (a) evaluate the gene expression profile and (b) identify the toxicities and potentially relevant human disease outcomes associated with long-term human exposure to environmental heavy metals in mining area using microarray analysis. For this purpose, 40 healthy male volunteers who were residents of a heavy metal-polluted area (Mahd Al-Dhahab city, Saudi Arabia) and 20 healthy male volunteers who were residents of a non-heavy metal-polluted area were included in the study. Total RNA was isolated from whole blood using PAXgene Blood RNA tubes and then reversed transcribed and hybridized to the gene array using the Affymetrix U219 GeneChip. Microarray analysis showed about 2129 genes were identified and differentially altered, among which a shared set of 425 genes was differentially expressed in the heavy metal-exposed groups. Ingenuity pathway analysis revealed that the most altered gene-regulated diseases in heavy metal-exposed groups included hematological and developmental disorders and mostly renal and urological diseases. Quantitative real-time polymerase chain reaction closely matched the microarray data for some genes tested. Importantly, changes in gene-related diseases were attributed to alterations in the genes encoded for protein synthesis. Renal and urological diseases were the diseases that were most frequently associated with the heavy metal-exposed group. Therefore, there is a need for further studies to validate these genes, which could be used as early biomarkers to prevent renal injury.
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Affiliation(s)
- Hesham M Korashy
- Department of Pharmacology & Toxicology, College of Pharmacy, King Saud University, P.O. Box 2457, Riyadh 11451, Saudi Arabia.
| | - Ibraheem M Attafi
- Department of Pharmacology & Toxicology, College of Pharmacy, King Saud University, P.O. Box 2457, Riyadh 11451, Saudi Arabia
| | - Konrad S Famulski
- Alberta Transplant Applied Genomics Centre, University of Alberta, Edmonton, AB T6G 2S2, Canada
| | - Saleh A Bakheet
- Department of Pharmacology & Toxicology, College of Pharmacy, King Saud University, P.O. Box 2457, Riyadh 11451, Saudi Arabia
| | - Mohammed M Hafez
- Department of Pharmacology & Toxicology, College of Pharmacy, King Saud University, P.O. Box 2457, Riyadh 11451, Saudi Arabia
| | - Abdulaziz M S Alsaad
- Department of Pharmacology & Toxicology, College of Pharmacy, King Saud University, P.O. Box 2457, Riyadh 11451, Saudi Arabia
| | - Abdul Rahman M Al-Ghadeer
- Central Laboratory, Research Center, College of Pharmacy, King Saud University, P.O. Box 2457, Riyadh 11451, Saudi Arabia
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Shah HS, Gao H, Morieri ML, Skupien J, Marvel S, Paré G, Mannino GC, Buranasupkajorn P, Mendonca C, Hastings T, Marcovina SM, Sigal RJ, Gerstein HC, Wagner MJ, Motsinger-Reif AA, Buse JB, Kraft P, Mychaleckyj JC, Doria A. Genetic Predictors of Cardiovascular Mortality During Intensive Glycemic Control in Type 2 Diabetes: Findings From the ACCORD Clinical Trial. Diabetes Care 2016; 39:1915-1924. [PMID: 27527847 PMCID: PMC5079609 DOI: 10.2337/dc16-0285] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/09/2016] [Accepted: 07/20/2016] [Indexed: 02/03/2023]
Abstract
OBJECTIVE To identify genetic determinants of increased cardiovascular mortality among subjects with type 2 diabetes who underwent intensive glycemic therapy in the Action to Control Cardiovascular Risk in Diabetes (ACCORD) trial. RESEARCH DESIGN AND METHODS A total of 6.8 million common variants were analyzed for genome-wide association with cardiovascular mortality among 2,667 self-reported white subjects in the ACCORD intensive treatment arm. Significant loci were examined in the entire ACCORD white genetic dataset (n = 5,360) for their modulation of cardiovascular responses to glycemic treatment assignment and in a Joslin Clinic cohort (n = 422) for their interaction with long-term glycemic control on cardiovascular mortality. RESULTS Two loci, at 10q26 and 5q13, attained genome-wide significance as determinants of cardiovascular mortality in the ACCORD intensive arm (P = 9.8 × 10-9 and P = 2 × 10-8, respectively). A genetic risk score (GRS) defined by the two variants was a significant modulator of cardiovascular mortality response to treatment assignment in the entire ACCORD white genetic dataset. Participants with GRS = 0 experienced a fourfold reduction in cardiovascular mortality in response to intensive treatment (hazard ratio [HR] 0.24 [95% CI 0.07-0.86]), those with GRS = 1 experienced no difference (HR 0.92 [95% CI 0.54-1.56]), and those with GRS ≥2 experienced a threefold increase (HR 3.08 [95% CI 1.82-5.21]). The modulatory effect of the GRS on the association between glycemic control and cardiovascular mortality was confirmed in the Joslin cohort (P = 0.029). CONCLUSIONS Two genetic variants predict the cardiovascular effects of intensive glycemic control in ACCORD. Further studies are warranted to determine whether these findings can be translated into new strategies to prevent cardiovascular complications of diabetes.
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Affiliation(s)
- Hetal S Shah
- Research Division, Joslin Diabetes Center, Boston, MA
- Department of Medicine, Harvard Medical School, Boston, MA
| | - He Gao
- Research Division, Joslin Diabetes Center, Boston, MA
- Department of Medicine, Harvard Medical School, Boston, MA
| | - Mario Luca Morieri
- Research Division, Joslin Diabetes Center, Boston, MA
- Department of Medicine, Harvard Medical School, Boston, MA
| | - Jan Skupien
- Research Division, Joslin Diabetes Center, Boston, MA
- Department of Medicine, Harvard Medical School, Boston, MA
- Department of Metabolic Diseases, Jagiellonian University Medical College, Krakow, Poland
| | - Skylar Marvel
- Bioinformatics Research Center and Department of Statistics, North Carolina State University, Raleigh, NC
| | - Guillaume Paré
- Department of Medicine and the Population Health Research Institute, McMaster University and Hamilton Health Sciences, Ontario, Canada
| | - Gaia C Mannino
- Research Division, Joslin Diabetes Center, Boston, MA
- Department of Medicine, Harvard Medical School, Boston, MA
| | - Patinut Buranasupkajorn
- Research Division, Joslin Diabetes Center, Boston, MA
- Department of Medicine, Harvard Medical School, Boston, MA
- Department of Medicine, Faculty of Medicine, Chulalongkorn University, Bangkok, Thailand
| | | | | | - Santica M Marcovina
- Department of Medicine, University of Washington, and Northwest Lipid Metabolism and Diabetes Research Laboratories, Seattle, WA
| | - Ronald J Sigal
- Departments of Medicine, Cardiac Sciences, and Community Health Sciences, Cumming School of Medicine, Faculties of Medicine and Kinesiology, University of Calgary, Alberta, Canada
| | - Hertzel C Gerstein
- Department of Medicine and the Population Health Research Institute, McMaster University and Hamilton Health Sciences, Ontario, Canada
| | - Michael J Wagner
- Center for Pharmacogenomics and Individualized Therapy, University of North Carolina at Chapel Hill, Chapel Hill, NC
| | - Alison A Motsinger-Reif
- Bioinformatics Research Center and Department of Statistics, North Carolina State University, Raleigh, NC
| | - John B Buse
- Department of Medicine, University of North Carolina School of Medicine, Chapel Hill, NC
| | - Peter Kraft
- Departments of Epidemiology and Biostatistics, Harvard T.H. Chan School of Public Health, Boston, MA
| | - Josyf C Mychaleckyj
- Center for Public Health Genomics, University of Virginia, Charlottesville, VA
| | - Alessandro Doria
- Research Division, Joslin Diabetes Center, Boston, MA
- Department of Medicine, Harvard Medical School, Boston, MA
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Czajka A, Ajaz S, Gnudi L, Parsade CK, Jones P, Reid F, Malik AN. Altered Mitochondrial Function, Mitochondrial DNA and Reduced Metabolic Flexibility in Patients With Diabetic Nephropathy. EBioMedicine 2015; 2:499-512. [PMID: 26288815 PMCID: PMC4534759 DOI: 10.1016/j.ebiom.2015.04.002] [Citation(s) in RCA: 126] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2015] [Revised: 03/27/2015] [Accepted: 04/03/2015] [Indexed: 01/09/2023] Open
Abstract
The purpose of this study was to determine if mitochondrial dysfunction plays a role in diabetic nephropathy (DN), a kidney disease which affects > 100 million people worldwide and is a leading cause of renal failure despite therapy. A cross-sectional study comparing DN with diabetes patients without kidney disease (DC) and healthy controls (HCs); and renal mesangial cells (HMCs) grown in normal and high glucose, was carried out. Patients with diabetes (DC) had increased circulating mitochondrial DNA (MtDNA), and HMCs increased their MtDNA within 24 h of hyperglycaemia. The increased MtDNA content in DCs and HMCs was not functional as transcription was unaltered/down-regulated, and MtDNA damage was present. MtDNA was increased in DC compared to HC, conversely, patients with DN had lower MtDNA than DC. Hyperglycaemic HMCs had fragmented mitochondria and TLR9 pathway activation, and in diabetic patients, mitophagy was reduced. Despite MtDNA content and integrity changing within 4 days, hyperglycaemic HMCs had a normal bio-energetic profile until 8 days, after which mitochondrial metabolism was progressively impaired. Peripheral blood mononuclear cells (PBMCs) from DN patients had reduced reserve capacity and maximal respiration, loss of metabolic flexibility and reduced Bioenergetic Health Index (BHI) compared to DC. Our data show that MtDNA changes precede bioenergetic dysfunction and that patients with DN have impaired mitochondrial metabolism compared to DC, leading us to propose that systemic mitochondrial dysfunction initiated by glucose induced MtDNA damage may be involved in the development of DN. Longitudinal studies are needed to define a potential cause–effect relationship between changes in MtDNA and bioenergetics in DN. Diabetic nephropathy may be a disease of acquired MtDNA damage and bioenergetic deficit. MtDNA content is increased in blood cells of diabetes patients and hyperglycaemic renal cells. Hyperglycaemia leads to renal cell MtDNA damage and subsequent bioenergetic dysfunction. Diabetic nephropathy patients have reduced circulating MtDNA , BHI and metabolic flexibility bioenergetic dysfunction and reduced metabolic flexibility and BHI.
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Affiliation(s)
- Anna Czajka
- Diabetes Research Group, Division of Diabetes and Nutritional Science, Faculty of Life Sciences and Medicine, King's College London, SE1 1UL, UK
| | - Saima Ajaz
- Diabetes Research Group, Division of Diabetes and Nutritional Science, Faculty of Life Sciences and Medicine, King's College London, SE1 1UL, UK
| | | | - Chandani Kiran Parsade
- Diabetes Research Group, Division of Diabetes and Nutritional Science, Faculty of Life Sciences and Medicine, King's College London, SE1 1UL, UK
| | - Peter Jones
- Diabetes Research Group, Division of Diabetes and Nutritional Science, Faculty of Life Sciences and Medicine, King's College London, SE1 1UL, UK
| | - Fiona Reid
- Department of Primary Care and Public Health Sciences
| | - Afshan N Malik
- Diabetes Research Group, Division of Diabetes and Nutritional Science, Faculty of Life Sciences and Medicine, King's College London, SE1 1UL, UK
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