Functional analysis of the novel mitochondrial tRNATrp and tRNASer(AGY) variants associated with type 2 diabetes mellitus

Figure 1 The secondary structures of mitochondrial tRNA^Trp and mitochondrial tRNA^Ser(AGY), arrows indicated the positions of the m. A5514G and m.C12237T variants. mt-tRNA: Mitochondrial tRNA.

Figure 2 Analysis of steady-state levels of mitochondrial tRNA^Trp and mitochondrial tRNA^Ser(AGY) by Northern blotting. A: 2 µg mitochondrial tRNA (mt-RNA) were electrophoresed through a denaturing polyacrylamide gel and hybridized with DIG-labeled oligonucleotide probes for mt-tRNA^Trp, mt-tRNA^Ser(AGY), and 5S rRNA; B: Qualification of mt-tRNA levels.

Figure 3 Analysis of mitochondrial functions in mutant and control cybrids. A: Adenosine triphosphate analysis; B: Mitochondrial membrane potential levels; C: Reactive oxygen species analysis; D: Nicotinamide adenine dinucleotide/NADH ratio; E: Mitochondrial DNA copy number; F: 8-hydroxy-deoxyguanine levels; G: Malondialdehyde levels; H: Superoxide dismutase levels. ATP: Adenosine triphosphate; MMP: Mitochondrial membrane potential; ROS: Reactive oxygen species; NAD: Nicotinamide adenine dinucleotide; mtDNA: Mitochondrial DNA; 8-OhdG: 8-hydroxy-deoxyguanine; MDA: Malondialdehyde; SOD: Superoxide dismutase.

Figure 4 Analysis of enzymatic activities of mitochondrial respiratory chain complexes in four cybrids with mitochondrial tRNA variants and four control cell lines without these variants. C: Control group; M: Mutant group.