RESUMO
PINK1 [phosphatase and tensin homologue (PTEN)-induced putative kinase 1] is a serine/threonine kinase targeted to mitochondria and implicated in early-onset recessive Parkinson's disease (PD). Through the phosphorylation of its downstream targets, PINK1 regulates multiple mitochondrial processes, including ATP production, stress-response and mitochondrial dynamics and quality control. The orchestration of such a wide array of functions by an individual kinase requires a fine-tuned and versatile regulation of its activity. PINK1 proteolytic processing, trafficking and localization, as well as different post-translational modifications, affect its activity and function. Unravelling the regulatory mechanisms of PINK1 is essential for a full comprehension of its kinase function in health and disease.
Assuntos
Mitocôndrias/metabolismo , Doença de Parkinson/metabolismo , Proteínas Quinases/metabolismo , Transporte Proteico/genética , Trifosfato de Adenosina/biossíntese , Humanos , Mitocôndrias/patologia , Doença de Parkinson/genética , Doença de Parkinson/patologia , Fosforilação , Proteínas Quinases/genética , Processamento de Proteína Pós-Traducional , Proteínas Serina-Treonina Quinases/metabolismoRESUMO
Under resting conditions, Pink1 knockout cells and cells derived from patients with PINK1 mutations display a loss of mitochondrial complex I reductive activity, causing a decrease in the mitochondrial membrane potential. Analyzing the phosphoproteome of complex I in liver and brain from Pink1(-/-) mice, we found specific loss of phosphorylation of serine-250 in complex I subunit NdufA10. Phosphorylation of serine-250 was needed for ubiquinone reduction by complex I. Phosphomimetic NdufA10 reversed Pink1 deficits in mouse knockout cells and rescued mitochondrial depolarization and synaptic transmission defects in pink(B9)-null mutant Drosophila. Complex I deficits and adenosine triphosphate synthesis were also rescued in cells derived from PINK1 patients. Thus, this evolutionary conserved pathway may contribute to the pathogenic cascade that eventually leads to Parkinson's disease in patients with PINK1 mutations.
Assuntos
Proteínas de Drosophila/metabolismo , Complexo I de Transporte de Elétrons/metabolismo , NADH Desidrogenase/metabolismo , Doença de Parkinson/enzimologia , Doença de Parkinson/genética , Proteínas Quinases/genética , Sequência de Aminoácidos , Animais , Encéfalo/enzimologia , Humanos , Fígado/enzimologia , Potencial da Membrana Mitocondrial/genética , Camundongos , Camundongos Knockout , Dados de Sequência Molecular , Mutação , Fosforilação/genética , Proteoma , Serina/química , Serina/metabolismoRESUMO
Growing axons are guided to their targets by attractive and repulsive cues. In the developing spinal cord, Netrin-1 and Shh guide commissural axons toward the midline. However, the combined inhibition of their activity in commissural axon turning assays does not completely abrogate turning toward floor plate tissue, suggesting that additional guidance cues are present. Here we show that the prototypic angiogenic factor VEGF is secreted by the floor plate and is a chemoattractant for commissural axons in vitro and in vivo. Inactivation of Vegf in the floor plate or of its receptor Flk1 in commissural neurons causes axon guidance defects, whereas Flk1 blockade inhibits turning of axons to VEGF in vitro. Similar to Shh and Netrin-1, VEGF-mediated commissural axon guidance requires the activity of Src family kinases. Our results identify VEGF and Flk1 as a novel ligand/receptor pair controlling commissural axon guidance.