The tRNAGly T10003C mutation in mitochondrial haplogroup M11b in a Chinese family with diabetes decreases the steady-state level of tRNAGly, increases aberrant reactive oxygen species production, and reduces mitochondrial membrane potential

Abstract

Mitochondrial diabetes originates mainly from mutations located in maternally transmitted, mitochondrial tRNA-coding genes. In a genetic screening program of type 2 diabetes conducted with a Chinese Han population, we found one family with suggestive maternally transmitted diabetes. The proband's mitochondrial genome was analyzed using DNA sequencing. Total 42 known nucleoside changes and 1 novel variant were identified, and the entire mitochondrial DNA sequence was assigned to haplogroup M11b. Phylogenetic analysis showed that a homoplasmic mutation, 10003T>C transition, occurred at the highly conserved site in the gene encoding tRNA(Gly). Using a transmitochondrial cybrid cell line harboring this mutation, we observed that the steady-state level of tRNA(Gly) significantly affected and the amount of tRNA(Gly) decreased by 97%, production of reactive oxygen species was enhanced, and mitochondrial membrane potential, mtDNA copy number and cellular oxygen consumption rate were remarkably decreased compared with wild-type cybrid cells. The homoplasmic 10003T>C mutation in the mitochondrial tRNA(Gly) gene suggested to be as a pathogenesis-related mutation which might contribute to the maternal inherited diabetes in the Han Chinese family.

Mitochondrial Genome (mtDNA) Mutations that Generate Reactive Oxygen Species

“…An increase in ROS production has been reported also for mutations in tRNA gly (m.T10003C) [72,76], tRNA met (m.C4467A) [77], tRNA his (T12201C) [78], tRNA trp (m.C5541T) [79], tRNA ala (m.T5655C), tRNA asp (m.A7551G), tRNA glu (m.A14692G), and slightly for tRNA thr (m.A15909G), which are often accompanied by a corresponding decrease in ATP production [72]. In addition, a patient bearing a tRNA val mutation (m.A1630G) suffering from gastrointestinal dysmotility and cachexia, presented with increased serum ferritin and lowered transferrin levels [80], both previously associated with a high ROS burden [81,82].…”

Mitochondrial tRNA mutations in Chinese children with tic disorders

“…[24,25]. We further identified the m.15910C>T variant in the D-stem of tRNA Thr and determined that this variant altered base pairing in the region, likely disrupting tRNA stability and functionality, as in the case of the m.7505T>C and m.10003T>C mutations [26][27][28]. The m.4373T>C anticodon stem variant was also predicted to adversely impact tRNA Gln stability in a manner similar to the m.15927G>A mutation in tRNA Thr [29].…”

The mitochondrial tRNAGly T10003C mutation may not be associated with diabetes mellitus

“…As a result, two potential articles concerning the association between the T10003C mutation and DM have been identified. After carefully reading the complete manuscripts, we found that one of them described a Chinese family with T2DM [ 15 ], while another paper, which met our inclusion criteria, reported a Chinese family with T2DM and deafness [ 16 ]. However, after carefully checking these reported families, it looked as if they were from the same family.…”

“…With this regard, this study reassessed the possible association between the T10003C mutation and DM. Database searches for the presence of this mutation led us to identify two potential records that were mentioned in the results sections [ 15 , 16 ]. Mutational analysis of the proband from the maternally inherited DM identified a set of polymorphisms; some of these were obviously pathogenic in the human population, for example, the G15924A mutation in the tRNA Thr gene, was reported to be a fatal infantile respiratory enzyme deficiency- associated pathogenic mutation [ 20 ].…”