二氢乳清酸脱氢酶突变对米勒综合征患者体内蛋白及功能的研究

Dihydroorotate dehydrogenase mutations lead to changes of protein and function in Miller syndrome

目的基于已知临床突变类型,即G202A、R346W和R135C,观察突变后相应蛋白功能变化。方法建立可稳定表达米勒综合征致病突变型G202A、R346W和R135C的宫颈癌细胞系。通过免疫组织化学和线粒体分层定位研究相应蛋白的线粒体定植功能、蛋白稳定性和酶活性。结果二氢乳清酸脱氢酶(DHODH)3种突变蛋白线粒体定植功能均未受影响,表达后均存在于线粒体内膜内。突变体G202A和R34W的蛋白稳定性降低;突变体R135C、蛋白稳定,但基底诱导酶活性受损致相应线粒体内酶活性缺失。结论 DHODH功能受损可能与米勒综合征症状相关联。

Objective To observe the changes of corresponding proteins and function based on known clinical dihydroorotate dehydrogenase（DHODH）mutation types,i.e.,G202 A,R346 W and R135 Cin the patients with Miller syndrome.Methods HeLa cell lines stably expressing Miller syndrome pathogenic mutation types G202 A,R346 Wand R135 Cwere established.Then the mitochondrial localization function,protein stability and enzyme activity of corresponding proteins were studied by the immunohistochemistry and mitochondrial layered positioning.Results The mitochondrial localization function of 3 kinds of DHODH mutation were not affected,which existed in the mitochondrial inner membrane after expression.The mutant G202 Aand R346 Wprotein stability was reduced;the mutant R135 Cprotein was stable,but base induced enzyme activity injury caused the deficiency of corresponding enzymatic activity.Conclusion The DHODH function injury may be related with the symptoms in Miller syndrome.