The Study of Mitochondrial Function in A Nonsyndromic Hearing Loss Family Carrying Mitochondria CO1/tRNASer(UCN) 7444G>A and 12S rRNA 1555A>G Mutations1

Abstract: In this study， we investigated the effects of 12S rRNA 1555A>G and CO1/tRNASer(UCN) 7444G>A mutations on mitochondria function through establishing platelet fusion cell lines with mitochondrial mutations. First， we collected the peripheral blood of control group， patients with 12S rRNA 1555A>G mutation， patients with CO1/ tRNASer(UCN) 7444G>A mutation and patients with both above mutations to establish platelet fusion cell lines. Second， we selected the satisfactory platelet fusion cell lines and studied their function including the amount of reactive oxvgen species (ROS) in cells， the level of mitochondrial membrane potential， the level of protein and the steady-state level of tRNA. We investigated the mitochondria function of platelet fusion cell lines in each group， compared with control group， cells with 12S rRNA 1555A>G mutation generated 66.54% more ROS with a 32.86% drop in ΔΨm level， cells with CO1/tRNASer(UCN) 7444G>A mutation generated 83.09% more ROS with a 0.66% drop in ΔΨm level， and cells with both above mutations generated 131.08% more ROS with a 29.86% drop in ΔΨm level. According to the results of Western blot， the levels of CO1， CO2， ND4， ND5 and ND6 in experimental groups decreased in different degrees compared with control group except for ND4， ND5 and ND6 in cells with 12S rRNA 1555A>G mutation which showed no significant difference. According to the results of Northern blot， 7444G>A mutation didn′t alter the steady-state level of tRNASer(UCN) obviously. Thus， CO1/ tRNASer(UCN) 7444G>A mutation might just be a modifying factor with regard to the pathological effects of gene with 12S rRNA 1555A>G mutation， but in the process of hearing loss， 12S rRNA 1555A>G mutation played a dominant role.

CSTR: 32200.14.cjcb.2018.05.0013