1
|
Huang C, Chen L, Li J, Ma J, Luo J, Lv Q, Xiao J, Gao P, Chai W, Li X, Zhang M, Hu F, Hu D, Qin P. Mitochondrial DNA Copy Number and Risk of Diabetes Mellitus and Metabolic Syndrome. J Clin Endocrinol Metab 2023; 109:e406-e417. [PMID: 37431585 DOI: 10.1210/clinem/dgad403] [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: 04/17/2023] [Revised: 07/04/2023] [Accepted: 07/06/2023] [Indexed: 07/12/2023]
Abstract
CONTEXT Mitochondrial DNA (mtDNA) plays a key role in diabetes mellitus and metabolic syndrome (MetS). An increasing number of studies have reported the association between mtDNA copy number (mtDNA-CN) and the risk of diabetes mellitus and MetS; however, the associations remain conflicted and a systematic review and meta-analysis on the association between mtDNA-CN and diabetes mellitus and MetS is lacking. OBJECTIVE We aimed to investigate the association of mtDNA-CN and diabetes mellitus and MetS using a systematic review and meta-analysis of observational studies. METHODS PubMed, EMBASE, and Web of Science were searched up to December 15, 2022. Random-effect models were used to summarize the relative risks (RRs) and 95% CIs. RESULTS A total of 19 articles were included in the systematic review and 6 articles (12 studies) in the meta-analysis involving 21 714 patients with diabetes (318 870 participants) and 5031 MetS (15 040 participants). Compared to the highest mtDNA-CN, the summary RR (95% CIs) for the lowest mtDNA-CN were 1.06 (95% CI, 1.01-1.12; I2 = 79.4%; n = 8) for diabetes (prospective study: 1.11 (1.02-1.21); I2 = 22.6%; n = 4; case-control: 1.27 (0.66-2.43); I2 = 81.8%; n = 2; cross-sectional: 1.01 (0.99-1.03); I2 = 74.7%; n = 2), and 1.03 (0.99-1.07; I2 = 70.6%; n = 4) for MetS (prospective: 2.87 (1.51-5.48); I2 = 0; n = 2; cross-sectional: 1.02 (1.01-1.04); I2 = 0; n = 2). CONCLUSION Decreased mtDNA-CN was associated with increased risk of diabetes mellitus and MetS when limited to prospective studies. More longitudinal studies are warranted.
Collapse
Affiliation(s)
- Cuihong Huang
- Center for Clinical Epidemiology and Evidence-based Medicine, Shenzhen Qianhai Shekou Free Trade Zone Hospital, Shenzhen, 518000, Guangdong, China
- School of Public Health, Sun Yat-Sen University, Guangzhou, 510080, Guangdong, China
| | - Lifang Chen
- Department of Cardiovascular Medicine, Shenzhen Qianhai Shekou Free Trade Zone Hospital, Shenzhen, 518000, Guangdong, China
| | - Jiangtao Li
- Department of Cardiovascular Medicine, Shenzhen Qianhai Shekou Free Trade Zone Hospital, Shenzhen, 518000, Guangdong, China
| | - Juanjuan Ma
- Center for Clinical Epidemiology and Evidence-based Medicine, Shenzhen Qianhai Shekou Free Trade Zone Hospital, Shenzhen, 518000, Guangdong, China
| | - Jun Luo
- Department of Cardiovascular Medicine, Shenzhen Qianhai Shekou Free Trade Zone Hospital, Shenzhen, 518000, Guangdong, China
| | - Qian Lv
- Department of Cardiovascular Medicine, Shenzhen Qianhai Shekou Free Trade Zone Hospital, Shenzhen, 518000, Guangdong, China
| | - Jian Xiao
- Department of Cardiovascular Medicine, Shenzhen Qianhai Shekou Free Trade Zone Hospital, Shenzhen, 518000, Guangdong, China
| | - Pan Gao
- Department of Neurology, Shenzhen University General Hospital, Shenzhen, 518000, Guangdong, China
| | - Wen Chai
- Department of Neurology, Shenzhen University General Hospital, Shenzhen, 518000, Guangdong, China
| | - Xu Li
- Department of Neurosurgery, The Second Affiliated Hospital of Shenzhen University, Shenzhen, 518000, Guangdong, China
| | - Ming Zhang
- Department of Biostatistics and Epidemiology, School of Public Health, Shenzhen University Health Science Center, Shenzhen, 518000, Guangdong, China
| | - Fulan Hu
- Department of Biostatistics and Epidemiology, School of Public Health, Shenzhen University Health Science Center, Shenzhen, 518000, Guangdong, China
| | - Dongsheng Hu
- Department of Biostatistics and Epidemiology, School of Public Health, Shenzhen University Health Science Center, Shenzhen, 518000, Guangdong, China
| | - Pei Qin
- Center for Clinical Epidemiology and Evidence-based Medicine, Shenzhen Qianhai Shekou Free Trade Zone Hospital, Shenzhen, 518000, Guangdong, China
| |
Collapse
|
2
|
Audzeyenka I, Rachubik P, Typiak M, Kulesza T, Topolewska A, Rogacka D, Angielski S, Saleem MA, Piwkowska A. Hyperglycemia alters mitochondrial respiration efficiency and mitophagy in human podocytes. Exp Cell Res 2021; 407:112758. [PMID: 34437881 DOI: 10.1016/j.yexcr.2021.112758] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/24/2021] [Revised: 07/15/2021] [Accepted: 07/26/2021] [Indexed: 12/19/2022]
Abstract
Podocytes constitute the outer layer of the renal glomerular filtration barrier. Their energy requirements strongly depend on efficient oxidative respiration, which is tightly connected with mitochondrial dynamics. We hypothesized that hyperglycemia modulates energy metabolism in glomeruli and podocytes and contributes to the development of diabetic kidney disease. We found that oxygen consumption rates were severely reduced in glomeruli from diabetic rats and in human podocytes that were cultured in high glucose concentration (30 mM; HG). In these models, all of the mitochondrial respiratory parameters, including basal and maximal respiration, ATP production, and spare respiratory capacity, were significantly decreased. Podocytes that were treated with HG showed a fragmented mitochondrial network, together with a decrease in expression of the mitochondrial fusion markers MFN1, MFN2, and OPA1, and an increase in the activity of the fission marker DRP1. We showed that markers of mitochondrial biogenesis, such as PGC-1α and TFAM, decreased in HG-treated podocytes. Moreover, PINK1/parkin-dependent mitophagy was inhibited in these cells. These results provide evidence that hyperglycemia impairs mitochondrial dynamics and turnover, which may underlie the remarkable deterioration of mitochondrial respiration parameters in glomeruli and podocytes.
Collapse
Affiliation(s)
- Irena Audzeyenka
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Institute, Polish Academy of Sciences, Wita Stwosza St. 63, 80-308, Gdansk, Poland; Faculty of Chemistry, University of Gdansk, Wita Stwosza St. 63, 80-308, Gdansk, Poland.
| | - Patrycja Rachubik
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Institute, Polish Academy of Sciences, Wita Stwosza St. 63, 80-308, Gdansk, Poland
| | - Marlena Typiak
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Institute, Polish Academy of Sciences, Wita Stwosza St. 63, 80-308, Gdansk, Poland
| | - Tomasz Kulesza
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Institute, Polish Academy of Sciences, Wita Stwosza St. 63, 80-308, Gdansk, Poland
| | - Anna Topolewska
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Institute, Polish Academy of Sciences, Wita Stwosza St. 63, 80-308, Gdansk, Poland; Faculty of Chemistry, University of Gdansk, Wita Stwosza St. 63, 80-308, Gdansk, Poland
| | - Dorota Rogacka
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Institute, Polish Academy of Sciences, Wita Stwosza St. 63, 80-308, Gdansk, Poland; Faculty of Chemistry, University of Gdansk, Wita Stwosza St. 63, 80-308, Gdansk, Poland
| | - Stefan Angielski
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Institute, Polish Academy of Sciences, Wita Stwosza St. 63, 80-308, Gdansk, Poland
| | - Moin A Saleem
- Bristol Renal, University of Bristol, Dorothy Hodgkin Building, Whitson Street, Bristol, BS1 3NY, United Kingdom
| | - Agnieszka Piwkowska
- Laboratory of Molecular and Cellular Nephrology, Mossakowski Medical Research Institute, Polish Academy of Sciences, Wita Stwosza St. 63, 80-308, Gdansk, Poland; Faculty of Chemistry, University of Gdansk, Wita Stwosza St. 63, 80-308, Gdansk, Poland
| |
Collapse
|
3
|
Cao H, Wu J, Luo J, Chen X, Yang J, Fang L. Urinary mitochondrial DNA: A potential early biomarker of diabetic nephropathy. Diabetes Metab Res Rev 2019; 35:e3131. [PMID: 30677222 DOI: 10.1002/dmrr.3131] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/14/2018] [Revised: 01/21/2019] [Accepted: 01/22/2019] [Indexed: 01/19/2023]
Abstract
BACKGROUND Mitochondrial dysfunction and chronic sterile inflammation are common features of type 2 diabetes. Therefore, we aimed to investigate whether mitochondrial DNA (mtDNA) could be a biomarker implicated in the progression of type 2 diabetes and diabetic nephropathy and explore the underlying mechanism. MATERIAL AND METHODS We developed a method for relative quantification of mtDNA content in clinical practice. qRT-PCR was used to measure the mtDNA content both in vivo in CD-1 mice with diabetes induction by streptozotocin and in vitro in murine endothelial cells and conditionally immortalized mouse podocytes. By pumping mtDNA into the mouse circulation, the effect of mtDNA on the kidney was assessed in mice. In patients with type 2 diabetes (n = 42; 24 males; mean age 57.9 ± 12.00 years), plasma mtDNA was evaluated. RESULTS Plasma mtDNA content was significantly decreased in patients with type 2 diabetes, particularly those with significant proteinuria. In vitro, high glucose treatment suppressed intracellular mtDNA content and facilitated the extracellular release of mtDNA, so excessive circulatory mtDNA induced by high glucose might be filtered through the kidney and then into urine. Indeed, urinary mtDNA content was significantly increased in both diabetic patients and mice. Moreover, by pumping excess mtDNA into circulation in mice, filtered mtDNA could trigger inflammation and induce kidney injury. CONCLUSION Excessive mtDNA filtered through the kidney under diabetic conditions may be involved in chronic renal inflammation. Reduced plasma mtDNA content and increased urinary mtDNA/creatinine ratio might play a potential role as an early biomarker of diabetic nephropathy.
Collapse
Affiliation(s)
- Hongdi Cao
- Department of Nephrology, 2nd Affiliated Hospital, Nanjing Medical University, Nanjing, China
| | - Jining Wu
- Department of Nephrology, 2nd Affiliated Hospital, Nanjing Medical University, Nanjing, China
| | - Jing Luo
- Department of Nephrology, 2nd Affiliated Hospital, Nanjing Medical University, Nanjing, China
| | - Xiaolan Chen
- Department of Nephrology, Affiliated Hospital of Nantong University, Nantong, China
| | - Junwei Yang
- Department of Nephrology, 2nd Affiliated Hospital, Nanjing Medical University, Nanjing, China
| | - Li Fang
- Department of Nephrology, Affiliated Hospital of Nantong University, Nantong, China
| |
Collapse
|
4
|
Santos JL, Cataldo LR, Cortés-Rivera C, Bravo C, Díaz-Casanova L, Martínez JA, Milagro FI, Galgani J. Plasma lactate and leukocyte mitochondrial DNA copy number as biomarkers of insulin sensitivity in non-diabetic women. J Physiol Biochem 2019; 75:285-297. [DOI: 10.1007/s13105-019-00672-w] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2018] [Accepted: 02/28/2019] [Indexed: 11/29/2022]
|
5
|
Lee JY, Lee DC, Im JA, Lee JW. Mitochondrial DNA copy number in peripheral blood is independently associated with visceral fat accumulation in healthy young adults. Int J Endocrinol 2014; 2014:586017. [PMID: 24707289 PMCID: PMC3953665 DOI: 10.1155/2014/586017] [Citation(s) in RCA: 43] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2013] [Revised: 12/22/2013] [Accepted: 01/01/2014] [Indexed: 11/17/2022] Open
Abstract
Aims. Visceral obesity is associated with an increased risk of cardiometabolic diseases and it is important to identify the underlying mechanisms. There is growing evidence that mitochondrial dysfunction is associated with metabolic disturbances related to visceral obesity. In addition, maintaining mitochondrial DNA (mtDNA) copy number is important for preserving mitochondrial function. Therefore, we investigated the relationship between mtDNA copy number and visceral fat in healthy young adults. Methods. A total of 94 healthy young subjects were studied. Biomarkers of metabolic risk factors were assessed along with body composition by computed tomography. mtDNA copy number was measured in peripheral leukocytes using real-time polymerase chain reaction (PCR) methods. Results. The mtDNA copy number correlated with BMI (r = -0.22, P = 0.04), waist circumference (r = -0.23, P = 0.03), visceral fat area (r = -0.28, P = -0.01), HDL-cholesterol levels (r = 0.25, P = 0.02), and hs-CRP (r = 0.32, P = 0.02) after adjusting for age and sex. Both stepwise and nonstepwise multiple regression analyses confirmed that visceral fat area was independently associated with mtDNA copy number (β = -0.33, P < 0.01, β = 0.32, and P = 0.03, resp.). Conclusions. An independent association between mtDNA content and visceral adiposity was identified. These data suggest that mtDNA copy number is a potential predictive marker for metabolic disturbances. Further studies are required to understand the causality and clinical significance of our findings.
Collapse
Affiliation(s)
- Jee-Yon Lee
- Department of Family Medicine, Severance Hospital, Yonsei University, College of Medicine, 250 Seongsanno, Seodaemun-gu 120-752, Republic of Korea
| | - Duk-Chul Lee
- Department of Family Medicine, Severance Hospital, Yonsei University, College of Medicine, 250 Seongsanno, Seodaemun-gu 120-752, Republic of Korea
| | - Jee-Aee Im
- Sport and Medicine Research Center, INTOTO Inc., 401 Dawoo BD, 90-6 Daeshin-Dong, Seodaemun-gu, Seoul 120-160, Republic of Korea
| | - Ji-Won Lee
- Department of Family Medicine, Severance Hospital, Yonsei University, College of Medicine, 250 Seongsanno, Seodaemun-gu 120-752, Republic of Korea
- *Ji-Won Lee:
| |
Collapse
|
6
|
Jun DW, Cho WK, Jun JH, Kwon HJ, Jang KS, Kim HJ, Jeon HJ, Lee KN, Lee HL, Lee OY, Yoon BC, Choi HS, Hahm JS, Lee MH. Prevention of free fatty acid-induced hepatic lipotoxicity by carnitine via reversal of mitochondrial dysfunction. Liver Int 2011; 31:1315-24. [PMID: 22093454 DOI: 10.1111/j.1478-3231.2011.02602.x] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/07/2010] [Accepted: 06/28/2011] [Indexed: 12/12/2022]
Abstract
BACKGROUND Mitochondria are the main sites for fatty acid oxidation and play a central role in lipotoxicity and nonalcoholic steatohepatitis. AIMS We investigated whether carnitine prevents free fatty acid (FFA)-induced lipotoxicity in vitro and in vivo. METHODS HepG2 cells were incubated with FFA, along with carnitine and carnitine complexes. Mitochondrial β-oxidation, transmembrane potential, intracellular ATP levels and changes in mitochondrial copy number and morphology were analysed. Otsuka Long-Evans Tokushima Fatty and Long-Evans Tokushima Otsuka rats were segregated into three experimental groups and fed for 8 weeks with (i) normal chow, (ii) a methionine choline-deficient (MCD) diet or (iii) an L-carnitine-supplemented MCD diet. RESULTS Carnitine prevented FFA-induced apoptosis (16% vs. 3%, P < 0.05). FFA treatment resulted in swollen mitochondria with increased inner matrix density and loss of cristae. However, mitochondria co-treated with carnitine had normal ultrastructure. The mitochondrial DNA copy number was higher in the carnitine treatment group than in the palmitic acid treatment group (375 vs. 221 copies, P < 0.05). The carnitine group showed higher mitochondrial β-oxidation than did the control and palmitic acid treatment groups (597 vs. 432 and 395 ccpm, P < 0.05). Carnitine treatment increased the mRNA expression of carnitine palmitoyltransferase 1A and peroxisome proliferator-activated receptor-γ, and carnitine-lipoic acid further augmented the mRNA expression. In the in vivo model, carnitine-treated rats showed lower alanine transaminase levels and lesser lobular inflammation than did the MCD-treated rats. CONCLUSIONS Carnitine and carnitine-lipoic acid prevent lipotoxicity by increasing mitochondrial β-oxidation and reducing intracellular oxidative stress.
Collapse
Affiliation(s)
- Dae Won Jun
- Department of Internal Medicine, Hanyang University School of Medicine, Seoul, Korea.
| | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
7
|
Malik AN, Shahni R, Rodriguez-de-Ledesma A, Laftah A, Cunningham P. Mitochondrial DNA as a non-invasive biomarker: accurate quantification using real time quantitative PCR without co-amplification of pseudogenes and dilution bias. Biochem Biophys Res Commun 2011; 412:1-7. [PMID: 21703239 DOI: 10.1016/j.bbrc.2011.06.067] [Citation(s) in RCA: 102] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2011] [Accepted: 06/08/2011] [Indexed: 02/07/2023]
Abstract
Circulating mitochondrial DNA (MtDNA) is a potential non-invasive biomarker of cellular mitochondrial dysfunction, the latter known to be central to a wide range of human diseases. Changes in MtDNA are usually determined by quantification of MtDNA relative to nuclear DNA (Mt/N) using real time quantitative PCR. We propose that the methodology for measuring Mt/N needs to be improved and we have identified that current methods have at least one of the following three problems: (1) As much of the mitochondrial genome is duplicated in the nuclear genome, many commonly used MtDNA primers co-amplify homologous pseudogenes found in the nuclear genome; (2) use of regions from genes such as β-actin and 18S rRNA which are repetitive and/or highly variable for qPCR of the nuclear genome leads to errors; and (3) the size difference of mitochondrial and nuclear genomes cause a "dilution bias" when template DNA is diluted. We describe a PCR-based method using unique regions in the human mitochondrial genome not duplicated in the nuclear genome; unique single copy region in the nuclear genome and template treatment to remove dilution bias, to accurately quantify MtDNA from human samples.
Collapse
Affiliation(s)
- Afshan N Malik
- King's College London, Diabetes Research Group, Division of Diabetes and Nutritional Sciences, School of Medicine, UK.
| | | | | | | | | |
Collapse
|
8
|
Reiling E, Ling C, Uitterlinden AG, Van't Riet E, Welschen LMC, Ladenvall C, Almgren P, Lyssenko V, Nijpels G, van Hove EC, Maassen JA, de Geus EJC, Boomsma DI, Dekker JM, Groop L, Willemsen G, 't Hart LM. The association of mitochondrial content with prevalent and incident type 2 diabetes. J Clin Endocrinol Metab 2010; 95:1909-15. [PMID: 20150578 DOI: 10.1210/jc.2009-1775] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
CONTEXT It has been shown that mitochondrial DNA (mtDNA) content is associated with type 2 diabetes (T2D) and related traits. However, empirical data, often based on small samples, did not confirm this observation in all studies. Therefore, the role of mtDNA content in T2D remains elusive. OBJECTIVE In this study, we assessed the heritability of mtDNA content in buccal cells and analyzed the association of mtDNA content in blood with prevalent and incident T2D. DESIGN AND SETTING mtDNA content from cells from buccal and blood samples was assessed using a real-time PCR-based assay. Heritability of mtDNA content was estimated in 391 twins from the Netherlands Twin Register. The association with prevalent T2D was tested in a case control study from The Netherlands (n = 329). Incident T2D was analyzed using prospective samples from Finland (n = 444) and The Netherlands (n = 238). MAIN OUTCOME MEASURES We measured the heritability of mtDNA content and the association of mtDNA content in blood with prevalent and incident T2D. RESULTS A heritability of mtDNA content of 35% (19-48%) was estimated in the twin families. We did not observe evidence of an association between mtDNA content and prevalent or incident T2D and related traits. Furthermore, we observed a decline in mtDNA content with increasing age that was male specific (P = 0.001). CONCLUSION In this study, we show that mtDNA content has a heritability of 35% in Dutch twins. There is no association between mtDNA content in blood and prevalent or incident T2D and related traits in our study samples.
Collapse
Affiliation(s)
- Erwin Reiling
- Leiden University Medical Center, Department of Molecular Cell Biology, P.O. Box 9600, 2300 RC Leiden, The Netherlands
| | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | | |
Collapse
|
9
|
Maggiolo F, Roat E, Pinti M, Nasi M, Gibellini L, De Biasi S, Airoldi M, Ravasio V, Mussini C, Suter F, Cossarizza A. Mitochondrial changes during D-drug-containing once-daily therapy in HIV-positive treatment-naive patients. Antivir Ther 2010; 15:51-9. [DOI: 10.3851/imp1483] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
|
10
|
Wang PW, Lin TK, Weng SW, Liou CW. Mitochondrial DNA variants in the pathogenesis of type 2 diabetes - relevance of asian population studies. Rev Diabet Stud 2009; 6:237-46. [PMID: 20043036 DOI: 10.1900/rds.2009.6.237] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
Mitochondrial dysfunction involves defective insulin secretion by pancreatic beta-cells, and insulin resistance in insulin-sensitive tissues such as muscle and adipose tissue. Mitochondria are recognized as the most important cellular source of energy, and the major generator of intracellular reactive oxygen species (ROS). Intracellular antioxidative systems have been developed to cope with increased oxidative damage. In case of minor oxidative stress, the cells may increase the number of mitochondria to produce more energy. A mechanism called mitochondrial biogenesis, involving several transcription factors and regulators, controls the quantity of mitochondria. When oxidative damage is advanced beyond the repair capacity of antioxidative systems, then oxidative stress can lead to cell death. Therefore, this organelle is central to cell life or death. Available evidence increasingly shows genetic linkage between mitochondrial DNA (mtDNA) alterations and type 2 diabetes (T2D). Based on previous studies, the mtDNA 16189 variant is associated with metabolic syndrome, higher fasting insulin concentration, insulin resistance index and lacunar cerebral infarction. These data support the involvement of mitochondrial genetic variation in the pathogenesis of T2D. Importantly, phylogeographic studies of the human mtDNAs have revealed that the human mtDNA tree is rooted in Africa and radiates into different geographic regions and can be grouped as haplogroups. The Asian populations carry very different mtDNA haplogroups as compared to European populations. Therefore, it is critically important to determine the role of mtDNA polymorphisms in T2D.
Collapse
Affiliation(s)
- Pei-Wen Wang
- Department of Internal Medicine, Chang Gung University College of Medicine, Chang Gung Memorial Hospital, Kaohsiung Medical Center, Kaohsiung, Taiwan 83305
| | | | | | | |
Collapse
|
11
|
Mitochondrial dysfunction and metabolic syndrome-looking for environmental factors. Biochim Biophys Acta Gen Subj 2009; 1800:282-9. [PMID: 19914351 DOI: 10.1016/j.bbagen.2009.11.010] [Citation(s) in RCA: 44] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2009] [Revised: 10/28/2009] [Accepted: 11/06/2009] [Indexed: 01/06/2023]
Abstract
The centerpiece of the pathophysiologic mechanism of metabolic syndrome is insulin resistance. Recently, it is becoming evident that mitochondrial dysfunction is closely related to insulin resistance and metabolic syndrome. The underlying mechanism of mitochondrial dysfunction is very complex, which includes genetic factors from both nuclear and mitochondrial genome and numerous environmental factors. Several mitochondrial DNA polymorphisms are associated with the components of metabolic syndrome. Numerous chemicals and drugs may cause mitochondrial dysfunction and insulin resistance. Notably, it was recently reported that serum levels of several mitochondrial toxins, such as persistent organic pollutants are associated with metabolic syndrome, which necessitates further investigation to reveal its precise mechanism. Given that the health impact of metabolic syndrome is tremendous, it is necessary to develop therapeutic modalities to correct mitochondrial dysfunction or at least to halt its aggravation. In this regard, exercise can improve both mitochondrial function and insulin sensitivity, and some pharmaceutical agents were reported to improve mitochondrial function. However, further studies are warranted to find more effective therapeutic strategies to treat mitochondrial dysfunction. By doing so, we can also shed light on the path of research for other diseases related to mitochondrial dysfunction.
Collapse
|
12
|
Cho YM, Park KS, Lee HK. Genetic factors related to mitochondrial function and risk of diabetes mellitus. Diabetes Res Clin Pract 2007; 77 Suppl 1:S172-7. [PMID: 17451836 DOI: 10.1016/j.diabres.2007.01.052] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Accepted: 01/29/2007] [Indexed: 01/07/2023]
Abstract
Mitochondria are the intracellular organelles responsible for the generation of ATP by the process of oxidative phosphorylation (OXPHOS) and have their own DNA containing genes for 13 subunits of OXPHOS and 2 rRNAs and 22 tRNAs for their protein synthesis machinery. Since mitochondrial DNA (mtDNA) has limited coding capacity, nuclear genes make a major contribution to mitochondrial architecture, metabolic systems and biogenesis. Nowadays, there is a growing body of evidence that the mitochondrial dysfunction plays a crucial role in the pathogenesis of type 2 diabetes. In this review, we showed that mtDNA copy number in peripheral blood cells is associated with various pathophysiological characteristics of type 2 diabetes such as insulin resistance and insulin secretory defect. In addition, peripheral blood mtDNA copy number is a risk factor for the development of type 2 diabetes. Common polymorphisms in mtDNA and nuclear genes regulating mitochondrial function might be associated with type 2 diabetes. Elucidation of genetic factors regulating mitochondrial function would be of help to understand how mitochondrial dysfunction is linked to the pathogenesis of type 2 diabetes.
Collapse
Affiliation(s)
- Young Min Cho
- Department of Internal Medicine, Seoul National University College of Medicine, 28 Yongon-dong Chongno-gu, Seoul 110-744, Korea
| | | | | |
Collapse
|
13
|
Jin CJ, Park HK, Cho YM, Pak YK, Lee KU, Kim MS, Friso S, Choi SW, Park KS, Lee HK. S-adenosyl-L-methionine increases skeletal muscle mitochondrial DNA density and whole body insulin sensitivity in OLETF rats. J Nutr 2007; 137:339-44. [PMID: 17237308 DOI: 10.1093/jn/137.2.339] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
Both mitochondrial dysfunction and alterations in mitochondrial DNA (mtDNA) are implicated in type 2 diabetes mellitus and insulin resistance. Evidence also suggests that metabolism of S-adenosyl-L-methionine (SAM), the universal methyl donor for biological methylation, is associated with mitochondrial dysfunction and insulin resistance. We investigated the effect of SAM on mtDNA density and insulin sensitivity using the Otsuka Long-Evans Tokushima Fatty (OLETF) rat, an animal model of type 2 diabetes mellitus and insulin resistance. To determine the short-term effect on mtDNA density, SAM (15 mg.kg-1.d-1) was administered intraperitoneally for 7 d to 6 male, 57-wk-old OLETF rats and 6 Long-Evans Tokushima Otsuka (LETO) rats of the same age as a nondiabetic control. To determine the long-term effect, the same dose of SAM was administered daily to 5 male, 6-wk-old OLETF rats until the age of 25 wk; 7 control OLETF rats received vehicle and 7 LETO rats were untreated. Skeletal muscle mtDNA density was measured by either competitive or multiplex PCR and insulin sensitivity was measured by hyperinsulinemic-euglycemic clamp. SAM treatment for 1 wk increased skeletal muscle mtDNA density of both OLETF and LETO rats. The long-term SAM treatment significantly reduced body weight gain as well as increased skeletal muscle mtDNA density and whole body insulin sensitivity in OLETF rats compared with their vehicle-treated controls. Furthermore, in all 3 groups, skeletal muscle mtDNA density correlated with insulin sensitivity (r=0.752, P<0.001). In conclusion, SAM treatment increased mtDNA density in the skeletal muscle, improved whole body insulin sensitivity, and prevented body weight gain in OLETF rats.
Collapse
Affiliation(s)
- Cheng Ji Jin
- Department of Internal Medicine, Seoul National University College of Medicine, Seoul 110-744, Korea
| | | | | | | | | | | | | | | | | | | |
Collapse
|
14
|
Choi YS, Hong JM, Lim S, Ko KS, Pak YK. Impaired coactivator activity of the Gly482 variant of peroxisome proliferator-activated receptor gamma coactivator-1alpha (PGC-1alpha) on mitochondrial transcription factor A (Tfam) promoter. Biochem Biophys Res Commun 2006; 344:708-12. [PMID: 16631115 DOI: 10.1016/j.bbrc.2006.03.193] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2006] [Accepted: 03/28/2006] [Indexed: 01/06/2023]
Abstract
Mitochondrial dysfunction may cause diabetes or insulin resistance. Peroxisome proliferation-activated receptor-gamma (PPAR-gamma) coactivator-1 alpha (PGC-1alpha) increases mitochondrial transcription factor A (Tfam) resulting in mitochondrial DNA content increase. An association between a single nucleotide polymorphism (SNP), G1444A(Gly482Ser), of PGC-1alpha coding region and insulin resistance has been reported in some ethnic groups. In this study, we investigated whether a change of glycine to serine at codon 482 of PGC-1alpha affected the Tfam promoter activity. The cDNA of PGC-1alpha variant bearing either glycine or serine at 482 codon was transfected into Chang human hepatocyte cells. The PGC-1alpha protein bearing glycine had impaired coactivator activity on Tfam promoter-mediated luciferase. We analyzed the PGC-1alpha genotype G1444A and mitochondrial DNA (mtDNA) copy number from 229 Korean leukocyte genomic DNAs. Subjects with Gly/Gly had a 20% lower amount of peripheral blood mtDNA than did subjects with Gly/Ser and Ser/Ser (p<0.05). No correlation was observed between diabetic parameters and PGC-1alpha genotypes in Koreans. These results suggest that PGC-1alpha variants with Gly/Gly at 482nd amino acid may impair the Tfam transcription, a regulatory function of mitochondrial biogenesis, resulting in dysfunctional mtDNA replication.
Collapse
Affiliation(s)
- Yon-Sik Choi
- Asan Institute for Life Sciences, University of Ulsan College of Medicine, Seoul, Republic of Korea
| | | | | | | | | |
Collapse
|
15
|
McCarty MF. Up-regulation of PPARγ coactivator-1α as a strategy for preventing and reversing insulin resistance and obesity. Med Hypotheses 2005; 64:399-407. [PMID: 15607577 DOI: 10.1016/j.mehy.2004.03.034] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2004] [Accepted: 03/21/2004] [Indexed: 12/25/2022]
Abstract
Excessive accumulation of triglycerides and certain fatty acid derivatives in skeletal muscle and other tissues appears to mediate many of the adverse effects of insulin resistance syndrome. Although fatty diets and obesity can promote such accumulation, deficient capacity for fatty acid oxidation can also contribute in this regard. Indeed, in subjects who are insulin resistant, diabetic, and/or obese, fatty acid oxidation by skeletal muscle tends to be inefficient, reflecting decreased expression of mitochondria and mitochondrial enzymes in muscle. This phenomenon is not corrected by weight loss, is not simply reflective of subnormal physical activity, and is also seen in lean first-degree relatives of diabetics; thus, it appears to be primarily attributable to genetic factors. Recent studies indicate that decreased expression of PPARgamma coactivator-1alpha (PGC-1alpha), a "master switch" which induces mitochondrial biogenesis by supporting the transcriptional activity of the nuclear respiratory factors, may largely account for the diminished oxidative capacity of subjects prone to insulin resistance. Thus, feasible measures which up-regulate PGC-1alpha may be useful for preventing and treating insulin resistance and obesity. These may include exercise training, metformin and other agents which stimulate AMP-activated kinase, high-dose biotin, and PPARdelta agonists. Drugs which are specific agonists for PPARdelta show remarkable efficacy in rodent models of insulin resistance, diabetes, and obesity, and are currently being evaluated clinically. Phytanic acid, a branched-chain fatty acid found in omnivore diets, can also activate PPARdelta, and thus should be examined with respect to its impact on mitochondrial biogenesis and insulin sensitivity.
Collapse
Affiliation(s)
- Mark F McCarty
- NutriGuard Research, 1051 Hermes Ave., Encinitas, CA 92024, USA.
| |
Collapse
|
16
|
Affiliation(s)
- Hong Kyu Lee
- Department of Internal Medicine, Seoul National University College of Medicine, 28 Yongon-dong Chongno-gu, Seoul, 110-744, Korea.
| |
Collapse
|
17
|
Abstract
Mitochondrial dysfunction secondary to mitochondrial and nuclear DNA mutations has been associated with energy deficiency in multiple organ systems and a variety of severe, often fatal, clinical syndromes. Although the production of energy is indeed the primary function of mitochondria, attention has also been directed toward their role producing reactive oxygen and nitrogen species and the subsequent widespread deleterious effects of these intermediates. The generation of toxic reactive intermediates has been implicated in a number of relatively common disorders, including neurodegenerative diseases, diabetes, and cancer. Understanding the role mitochondrial dysfunction plays in the pathogenesis of common disorders has provided unique insights into a number of diseases and offers hope for potential new therapies.
Collapse
Affiliation(s)
- Gregory M Enns
- Department of Pediatrics, Division of Medical Genetics, Stanford University, 300 Pasteur Drive, H-315, Stanford, CA 94305-5208, USA.
| |
Collapse
|
18
|
Lee HK. Method of proof and evidences for the concept that mitochondrial genome is a thrifty genome. Diabetes Res Clin Pract 2001; 54 Suppl 2:S57-63. [PMID: 11733110 DOI: 10.1016/s0168-8227(01)00336-9] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/23/2023]
Abstract
A hypothesis that mitochondrial genome itself is the thrifty genome has been advanced, as both its mutation, or quality, and amount in the peripheral blood, or quantity, are found to have close relationship to diabetes mellitus, or more specifically insulin resistance. Mere presence of relationship, however, does not establish cause-effect relation. Usually a genetic 'cause' is established, when a knockout of putative gene produces disease phenotype. However, absence of mitochondrial genome is incompatible with life. Here the argument advanced by Bradford Hill was applied to the proof of a hypothesis, as most of the data are from epidemiological observations; it is biologically plausible that both mtDNA quality and quantity are related to insulin resistance. The relationship had enough strength of association, dose-response relation, and consistency of relationship. Temporally association, decrease of mtDNA content preceding onset of diabetes, was also observed. Good hypothesis generates many predictions, which could be verified experimentally and which is biologically plausible.
Collapse
Affiliation(s)
- H K Lee
- Department of Internal Medicine, Seoul National University College of Medicine, 28 Yongon-dong, Chongno-gu, 110744, Seoul, South Korea.
| |
Collapse
|