Creation of human/mouse mitochondrial chimera model carrying A3243G mutation and exploring pathogenesis of mtDNA A3243G in vivo
mtDNA A3243G 点突变小鼠模型的建立及其致病机制探讨

Generation of chimera mice with human mitochondria carrying A3243G mutation by microinjection technique could provide an ideal model for studying how xeno-mitochondrial DNA is transmitted to following generations and distributed in various tissues and exploring the effect of A3243G mutation on mitochondrial function in vivo.Viable mitochondria fractionated from leukocytes of healthy adults and type 2 diabetes mellitus patients(2-DM) carrying A3243G,were microinjected into mouse zygotes.After transplantation into recipient mice,human mitochondrial DNA was detected in resulting progenies by molecular biology methods.Measurements of fasting blood glucose and blood lactate were performed on transmitochondrial mice.The level of reactive oxygen species(ROS) was analyzed in tissues of transmitochondrial mice by fluorescence spectrophotometric method.Mitochondrial respiratory activity was measured by spectrophotometrical method.Results show(1) 3 mice(1 female injected the mitochondria from healthy adults and 2 male injected the mitochondria from type 2 DM patients) harbored human mitochondrial DNA;(2) the pathogenic A3243G mutation was detected in 2 males;(3) human mitochondrial DNA was found in the offspring after chimera female mice were mated to wild type C57/BL6J;(4) xenomitochondrial DNA was expressed only in part tissues;(5) the level of ROS in the tissues harboring A3243G mutation was higher than in normal tissues;(6) the activity of mitochondria enzyme in the tissues with A3243G was lower than in normal tissues.These results demonstrated that ROS increased by A3243G mutation could hurt the function of mitochondria.Human/mouse mitochondrial chimeras were successfully generated by microinjection,harboring pathogenic point mutation of mtDNA.A new strategy was provided for production of animal models of mitochondrial disorders.