Ding Yu, Yu Xue-Jiao, Guo Qin-Xian, Leng Jian-Hang
Central Laboratory, Hangzhou First People's Hospital, Hangzhou 310006, Zhejiang Province, China.
Clinical Laboratory, Quzhou People's Hospital, Quzhou 324000, Zhejiang Province, China.
World J Diabetes. 2024 Aug 15;15(8):1753-1763. doi: 10.4239/wjd.v15.i8.1753.
Mutations in mitochondrial tRNA () genes that result in mitochondrial dysfunction play important roles in type 2 diabetes mellitus (T2DM). We pre-viously reported a large Chinese pedigree with maternally inherited T2DM that harbors novel and variants, however, the effects of these variants on T2DM progression are largely unknown.
To assess the potential pathogenicity of T2DM-associated and variants at genetic, molecular, and biochemical levels.
Cytoplasmic hybrid (cybrid) cells carrying both and variants, and healthy control cells without these mitochondrial DNA (mtDNA) variants were generated using trans-mitochondrial technology. Mitochondrial features, including steady-state level, levels of adenosine triphosphate (ATP), mitochondrial membrane potential (MMP), reactive oxygen species (ROS), mtDNA copy number, nicotinamide adenine dinucleotide (NAD)/NADH ratio, enzymatic activities of respiratory chain complexes (RCCs), 8-hydroxy-deo-xyguanine (8-OhdG), malondialdehyde (MDA), and superoxide dismutase (SOD) were examined in cell lines with and without these variants.
Compared with control cells, the variant caused an approximately 35% reduction in the steady-state level of ( < 0.0001); however, the variant did not affect the steady-state level ( = 0.5849). Biochemical analysis revealed that cells with both and variants exhibited more severe mitochondrial dysfunctions and elevated oxidative stress than control cells: ATP, MMP, NAD/NADH ratio, enzyme activities of RCCs and SOD levels were markedly decreased in mutant cells ( < 0.05 for all measures). By contrast, the levels of ROS, 8-OhdG and MDA were significantly increased ( < 0.05 for all measures), but mtDNA copy number was not affected by and variants ( = 0.5942).
The variant impaired metabolism, which subsequently caused mitochondrial dysfunction. The variant did not alter the steady-state level of , indicating that it may be a modifier of the variant. The variant may exacerbate the pathogenesis and progression of T2DM in this Chinese pedigree.
线粒体tRNA（）基因的突变导致线粒体功能障碍，在2型糖尿病（T2DM）中起重要作用。我们之前报道了一个中国的大型母系遗传T2DM家系，其中存在新的和变体，然而，这些变体对T2DM进展的影响很大程度上未知。
在基因、分子和生化水平评估与T2DM相关的和变体的潜在致病性。
使用转线粒体技术构建携带和变体的细胞质杂种（cybrid）细胞，以及不携带这些线粒体DNA（mtDNA）变体的健康对照细胞。检测了有和没有这些变体的细胞系中的线粒体特征，包括稳态水平、三磷酸腺苷（ATP）水平、线粒体膜电位（MMP）、活性氧（ROS）、mtDNA拷贝数、烟酰胺腺嘌呤二核苷酸（NAD）/还原型烟酰胺腺嘌呤二核苷酸（NADH）比值、呼吸链复合物（RCCs）的酶活性、8-羟基脱氧鸟嘌呤（8-OhdG）、丙二醛（MDA）和超氧化物歧化酶（SOD）。
与对照细胞相比，变体导致稳态水平降低约35%（<0.0001）；然而，变体不影响稳态水平（=0.5849）。生化分析显示，携带和变体的细胞比对照细胞表现出更严重的线粒体功能障碍和氧化应激升高：突变细胞中的ATP、MMP、NAD/NADH比值、RCCs酶活性和SOD水平显著降低（所有测量值<0.05）。相比之下，ROS、8-OhdG和MDA水平显著升高（所有测量值<0.05），但mtDNA拷贝数不受和变体影响（=0.5942）。
变体损害了代谢，随后导致线粒体功能障碍。变体未改变的稳态水平，表明它可能是变体的修饰因子。变体可能会加剧这个中国家系中T2DM的发病机制和进展。
