Mitochondrial DNA deletions of blood lymphocytes as genetic markers of low folate-related mitochondrial genotoxicity in peripheral tissues.
BACKGROUND
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.


OBJECTIVE
The aim of this study was to characterize folate-related mtDNA deletions in lymphocytes and their associations with mt genotoxicity in peripheral tissues.


METHODS
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.


RESULTS
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.
Department of Nutritional Science, Fu-Jen University, Hsinchuang 242, Taipei County, Taiwan.
Yi-Fang
YF
Chou
Rwei-Fen S
RF
Huang
D000704:Analysis of Variance; D000818:Animals; D003600:Cytosol / Q000378:metabolism; D004249:DNA Damage; D004272:DNA, Mitochondrial / Q000097:blood / Q000235:genetics* / Q000378:metabolism; D004064:Digestive System / Q000378:metabolism; D004912:Erythrocytes / Q000378:metabolism; D005492:Folic Acid / Q000008:administration & dosage* / Q000097:blood / Q000378:metabolism; D005494:Folic Acid Deficiency / Q000150:complications / Q000235:genetics / Q000378:metabolism*; D017353:Gene Deletion; D005819:Genetic Markers; D008214:Lymphocytes / Q000378:metabolism*; D008297:Male; D016555:Matched-Pair Analysis; D008928:Mitochondria / Q000235:genetics* / Q000378:metabolism; D009752:Nutritional Status; D009928:Organ Specificity; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D013997:Time Factors; D014886:Weaning
D004272:DNA, Mitochondrial; D005819:Genetic Markers; D005492:Folic Acid