Association of mitochondrial genome mutations with lipofibrous plaques in human aortic intima

Abstract

Atherosclerosis is a basis of development for many cardiovascular diseases, which are leading causes of death among people in the 21-st century. One of possible causes of atherosclerosis may be somatic mutations of human mitochondrial genome. In order to identify mutations associated with atherosclerosis, we analyzed 42 mitochondrial mutations found in various pathologies. The subject of the study were individuals who died as a result of an accident or a sudden death. The material for the investigation were segments of intima from 7 aortas both normal and with lipofibrous plaques. DNA was isolated by a method of phenol-chloroform extraction. PCR-fragments of DNA containing the region of investigated mutations were analyzed by an original method of quantitative assessment of mitochondrial genome mutant alleles. This method was developed in our laboratory on the basis of pyrosequencing technology. Statistical data processing was performed using IBM SPSS Statistics 21.0 and by bootstrap analysis. 40 of 42 studied mutations were heteroplasmic and two were homoplasmic according to the absence of a mutant allele in atherosclerosis. The developed method of direct quantitative assessment of mitochondrial genome mutant alleles helped us to find three new mutations: 652delG, 961delC and 5132insAA. It was found that 11 of mitochondrial mutations (652insG, T3336S, C3256T, G14459A, G14846A, G15059A, 652delG, A1555G, C5178A, G13513A and G12315A), belonging to eight mitochondrial genes: rRNA 12S, tRNA — Leu (codon recognition UUR) and tRNA — Leu (codon recognition CUN), subunit 1, 2, 5 and 6 of NADH dehydrogenase and cytochrome B are potentially associated with atherosclerosis, because from 29% (2 of 7 aortas) to 86% (6/7) investigated aortas have a significant difference in the heteroplasmy level of these mutations in lipofibrous plaques compared to normal aortic intima.