Premature ovarian insufficiency may be associated with the mutations in mitochondria tRNA genes

Premature ovarian insufficiency (POI) is a common endocrine disorder featured by the triad constituting of amenorrhea for at least four months, to date, the molecular pathogenesis of POI is largely undetermined. Despite several investigations have reported an increase in reactive oxygen species (ROS) content in idiopathic POI, the role of mitochondrial DNA (mtDNA) mutations/variants in the progression of POI has not been widely investigated. The current study aimed to explore the association between mt-tRNA mutations/variants and POI; we first used the PCR-Sanger sequencing to detect the mutations/variants in mt-tRNA genes from 50 POI patients and 30 healthy subjects. In addition, we evaluated the mitochondrial functions by using trans-mitochondrial cybrid cells containing these potential pathogenic mt-tRNA mutations. Consequently, five mutations: tRNA(Leu(UUR)) C3303T, tRNA(Met) A4435G, tRNA(Gln) T4363C, tRNA(Cys) G5821A and tRNA(Thr) A15951G were identified. Notably, these mutations occurred at the extremely conserved nucleotides of the corresponding mt-tRNAs and may result the failure in mt-tRNA metabolism and subsequently lead to the impairment in mitochondrial protein synthesis. Furthermore, biochemical and molecular analyses of the cybrid cells containing these mutations showed a significantly lower level of All' production when compared with the controls, whereas the ROS levels were much higher in POI patients carrying these mt-tRNA mutations, strongly indicated that these mt-tRNA mutations may cause the mitochondrial dysfunction, and play active roles in the progression and pathogensis of POI. Together, this study shaded additional light on the molecular mechanism of POI that was manifestated by mt-tRNA mutations.