RESUMO
Parkinson's disease (PD) is a progressive neurodegenerative illness associated with a selective loss of dopaminergic neurons in the nigrostriatal pathway of the brain. Despite the overall rarity of the familial forms of PD, the identification of single genes linked to the disease has yielded crucial insights into possible mechanisms of neurodegeneration. Recently, a putative mitochondrial kinase, PINK1, has been found mutated in an inherited form of parkinsonism. Here, we describe that PINK1 mutations confer different autophosphorylation activity, which is regulated by the C-terminal portion of the protein. We also demonstrate the mitochondrial localization of both wild-type and mutant PINK1 proteins unequivocally and prove that a short N-terminal part of PINK1 is sufficient for its mitochondrial targeting.
Assuntos
Genes Recessivos , Mitocôndrias/metabolismo , Transtornos Parkinsonianos/enzimologia , Transtornos Parkinsonianos/genética , Proteínas Quinases/genética , Sequência de Aminoácidos , Animais , Células COS , Chlorocebus aethiops , Códon sem Sentido , Células HeLa , Humanos , Líquido Intracelular/enzimologia , Líquido Intracelular/metabolismo , Modelos Moleculares , Dados de Sequência Molecular , Mutação de Sentido Incorreto , Fosforilação , Proteínas Quinases/metabolismo , Estrutura Terciária de Proteína , Transporte Proteico , SolubilidadeRESUMO
Mmutations in paraplegin, a putative mitochondrial metallopeptidase of the AAA family, cause an autosomal recessive form of hereditary spastic paraplegia (HSP). Here, we analyze the function of paraplegin at the cellular level and characterize the phenotypic defects of HSP patients' cells lacking this protein. We demonstrate that paraplegin coassembles with a homologous protein, AFG3L2, in the mitochondrial inner membrane. These two proteins form a high molecular mass complex, which we show to be aberrant in HSP fibroblasts. The loss of this complex causes a reduced complex I activity in mitochondria and an increased sensitivity to oxidant stress, which can both be rescued by exogenous expression of wild-type paraplegin. Furthermore, complementation studies in yeast demonstrate functional conservation of the human paraplegin-AFG3L2 complex with the yeast m-AAA protease and assign proteolytic activity to this structure. These results shed new light on the molecular pathogenesis of HSP and functionally link AFG3L2 to this neurodegenerative disease.
Assuntos
Complexo I de Transporte de Elétrons/metabolismo , Metaloendopeptidases/deficiência , Metaloendopeptidases/metabolismo , Mitocôndrias/enzimologia , Paraplegia Espástica Hereditária/enzimologia , Proteases Dependentes de ATP , ATPases Associadas a Diversas Atividades Celulares , Adenosina Trifosfatases/genética , Adenosina Trifosfatases/metabolismo , Respiração Celular/genética , Células Cultivadas , Regulação para Baixo/genética , Complexo I de Transporte de Elétrons/deficiência , Fibroblastos , Humanos , Membranas Intracelulares/metabolismo , Substâncias Macromoleculares , Metaloendopeptidases/genética , Estresse Oxidativo/genética , Filogenia , Espécies Reativas de Oxigênio/farmacologia , Saccharomyces cerevisiae/enzimologia , Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/genética , Proteínas de Saccharomyces cerevisiae/metabolismo , Homologia de Sequência do Ácido Nucleico , Paraplegia Espástica Hereditária/genéticaRESUMO
Headache attacks and autonomic dysfunctions characterize migraine, a very common, disabling disorder with a prevalence of 12% in the general population of Western countries. About 20% of individuals affected with migraine experience aura, a visual or sensory-motor neurological dysfunction that usually precedes or accompanies the headache. Although the mode of transmission is controversial, population-based and twin studies have implicated genetic factors, especially in migraine with aura. Familial hemiplegic migraine is a hereditary form of migraine characterized by aura and some hemiparesis. Here we show that mutations in the gene ATP1A2 that encodes the alpha2 subunit of the Na+/K+ pump are associated with familial hemiplegic migraine type 2 (FHM2) linked to chromosome 1q23 (OMIM 602481). Functional data indicate that the putative pathogenetic mechanism is triggered by a loss of function of a single allele of ATP1A2. This is the first report associating mutations of Na+K+ pump subunits to genetic diseases.
