Key Role Of A Novel Mitochondrial TRNA^Ala T5655C Mutation Associated With The Essential Hypertention

Hypertension is a complex medical condition caused by interactions between the environment and inherited disorder. By now, the hypertension is difficult to cure and the patients of hypertension are treated with a series of medicine to control the blood pressure. Although maternal transimission of hypertension has been observed in some pedigrees, the pathophysiology of matrilineal genetic hypertension is not clear. Mitochondrion exists in all eukaryotes as the main source of energy. The mitochondrial genome encodes2rRNAs,22tRNAs and13subunits of oxidative phosphorylation complexes. Thus disfunction of mitochondria may influence the oxidative phosphorylation and ATP synthesis, leading to a series of mitochondrial defect and further induce neurodegenerative diseases, metabolic diseases, encephalomyopathy and cancers. Mitochondrial dysfunction, caused by mitochondrial DNA mutations, is mainly responsible for hypertension, but the mechanism has not been elucidated. A total of45subjects from a large Chinese family underwent clinical, genetic, molecular, and biochemical evaluations. Tweleve of19adult matrilineal relatives exhibited a wide range of severity in essential hypertension, whereas none of the offspring of affected fathers had hypertension. Mutational analysis of their mitochondrial genomes identified a novel homoplasmic5655T>C mutation located at the processing site for the tRNAAla5’-end precursor. We have established a rapid accurate enzyme identification method to identify the mitochondria T5655C mutation. An in vitro processing analysis showed that the5655T>C mutation reduced the efficiency of the tRNAAla precursor5’-end cleavage catalyzed by RNase P. Cybrids are the great model for studying the functional effects of mitochondrial genes and mitochondrial diseases for their consistent nuclear background. We have successfully constructed transmitochondrial cybrids harboring the mitochondrial5655T>C mutation and without mutation using lymphocytes of the proband and the same haplotype control as donor cells, which provide the material for subsequent cellular function. At the same time, we test the levels of the ROS generation of the cybrids.The ratio of geometric mean intensity between unstimulated and stimulated with H2O2in each cell line was calculated to delineate the reaction on increasing level of ROS under oxidative stress.The the levels of the ROS generation of the cybrids with mutation are higer, with an average108%(p=0.0043) of the mean value measured in the control cell line. These data provide direct evidence that mitochondrial dysfunction caused by mitochondrial tRNAA a5655T>C mutation may be involved in essential hypertension. Our findings may provide new insights into pathophysiology of maternally transmitted hypertension. In the following study, we will detect the ATP synthesis, the oxygen consumption rate and the mitochondrial protein synthesis of the cybrids with mitochondrial T5655C mutation, along with the mitochondria compensation analysis experiments of AARS2protein in the mitochondria, to further explore the pathogenesis mechanism of mitochondria tRNAAla T5655C in maternally inherited essential hypertension.