Mitochondrial DNA deletions of blood lymphocytes as genetic markers of low folate-related mitochondrial genotoxicity in peripheral tissues
- 191 Downloads
A low folate status and mitochondrial DNA (mtDNA) mutations are risk factors for various cancers and degenerative diseases. It is not known if lymphocytic mtDNA deletions can be used as genetic “markers” to reflect global mtDNA damage during folate deficiency.
Aim of the study
The aim of this study was to characterize folate-related mtDNA deletions in lymphocytes and their associations with mt genotoxicity in peripheral tissues.
Weaning Wistar rats were fed folate-deficient and folate-replete (control) diets for 2 and 4 weeks. Folate levels of blood lymphocytes and various tissues were assayed by the Lactobacillus casei method. mtDNA deletions were measured by a real-time polymerase chain reaction analysis of whole DNA extracts.
Compared to the control counterparts, mtDNA deletions of lymphocytes increased by 3.5-fold (P < 0.05) after 4 weeks of folate deficiency. Lymphocytic mtDNA deletions were inversely associated with plasma (r = −0.619, P = 0.018), red blood cell (r = −0.668, P = 0.009), and lymphocytic folate levels (r = −0.536, P = 0.048). Frequencies of lymphatic mtDNA deletions were positively correlated with mtDNA deletions in tissues including the lungs (r = 0.803, P = 0.0005), muscles (r = 0.755, P = 0.001), heart (r = 0.633, P = 0.015), liver (r = 0.722, P = 0.003), kidneys (r = 0.737, P = 0.006), pancreas (r = 0.666, P = 0.009), and brain (r = 0.917, P < 0.0001). Conclusions: Our data demonstrate that accumulated mtDNA deletions of lymphocytes depended upon dietary folate deprivation. The accumulated mt deletions in lymphocytes closely reflected the mt genotoxicity in the peripheral tissues during folate deficiency.
KeywordsFolate deficiency mtDNA deletions Lymphocytes Genetic marker Peripheral tissues
- mtDNA4834 deletion
4,834-bp large deletion in mtDNA
Reactive oxygen species
The authors are deeply grateful to Prof. Y.-H. Wei of the Department of Biochemistry at National Yang-Ming University, Taipei, Taiwan for his kind support and invaluable advice on mtDNA mutations. This study was supported by a grant (NSC96-2320-B-002) from the National Science Council, Taiwan to R.F.S. Huang.
- 2.Branda RF, Brooks EM, Chen Z, Naud SJ, Nicklas JA (2002) Dietary modulation of mitochondrial DNA deletions and copy number after chemotherapy in rats. Mutat Res 501:29–36Google Scholar
- 4.Choi SW, Mason JB (2000) Folate and carcinogenesis: an integrated scheme. J Nutr 130:129–135Google Scholar
- 5.Chou YF, Yu CC, Huang RFS (2007) Changes in mitochondrial (mt) DNA deletion, content and biogenesis in folate-deficient tissues of young rats depend on mt folate and oxidative DNA injuries. J Nutr 100:596–602Google Scholar
- 8.Crott JW, Choi SW, Branda RF, Mason JB (2002) Accumulation of mitochondrial DNA deletions is age, tissue and folate-dependent in rats. Mutat Res 570:63–70Google Scholar
- 11.Fenech M (2001) The role of folic acid and vitamin B12 in genomic stability of human cells. Mutat Res 475:51–67Google Scholar
- 14.Horne DW, Patterson D (1988) Lactobacillus casei microbiological assay of folic acid derivatives in 96-well microtiter plates. Clin Chem 34:2357–2359Google Scholar
- 15.Huang RFS, Hsu YC, Lin HL, Yang FL (2001) Folate depletion and elevated plasma homocysteine promote oxidative stress in rat livers. J Nutr 131:33–38Google Scholar
- 21.Lee HC, Pang CY, Hsu HS, Wei YH (1994) Differential accumulations of 4977 bp deletion in mitochondrial DNA of various tissues in human ageing. Biochim Biophys Acta 1226:37–43Google Scholar
- 29.Moraes CT, DiMauro S, Zeviani M, Lombes A, Shanske S, Miranda AF, Nakase H, Bonilla E, Werneck LC (1989) Mitochondrial DNA deletions in progressive external ophthalmoplegia and Kearns–Sayre syndrome. N Engl J Med 320:1293–1299Google Scholar
- 31.Rampersaud GC, Kauwell GP, Hutson AD, Cerda JJ, Bailey LB (2000) Genomic DNA methylation decreases in response to moderate folate depletion in elderly women. Am J Clin Nutr 72:998–1003Google Scholar
- 34.Varela-Moreiras G, Selhub J (1992) Long-term folate deficiency alters folate content and distribution differentially in rat tissues. J Nutr 122:986–991Google Scholar
- 36.Von Wurmb N, Oehmichen M, Meissner C (1998) Demonstration of the 4977 bp deletion in human mitochondrial DNA from intravital and postmortem blood. Mutat Res 422:247–254Google Scholar
- 37.Walzem RL, Clifford AJ (1988) Folate deficiency in rats fed diets containing free amino acid or intact proteins. J Nutr 118:1089–1096Google Scholar
- 39.Wei YH (1992) Mitochondrial DNA alterations as ageing-associated molecular events. Mutat Res 275:145–155Google Scholar
- 40.Wei YH, Lee HC (2002) Oxidative stress, mitochondrial DNA mutation, and impairment of antioxidant enzymes in aging. Exp Biol Med (Maywood) 227:671–682Google Scholar
- 41.Wei YH (1998) Oxidative stress and mitochondrial DNA mutations in human aging. Proc Soc Exp Biol Med 217:53–63Google Scholar
- 42.Wei YH, Pang CY, Lee HC, Lu CY (1998) Roles of mitochondrial DNA mutation and oxidative damage in human aging. Curr Sci 74:887–893Google Scholar
- 43.Yin PH, Lee HC, Chau GY, Wu YT, Li SH, Liu WY, Wei YH, Liu TY, Chi CW (2004) Alteration of the copy number and deletion of mitochondrial DNA in human hepatocellular carcinoma. Br J Cancer 90:2390–2392Google Scholar