Characterization of the potential role of myosin IIa in parkin translocation during mitopahgy

Mitochondria are important organelles of eukaryotic cells that provide energy through cellular respiration. Cells have evolved several quality control mechanisms to preserve functional mitochondria and avoid cell damage. Damaged mitochondria are recognized and removed by mitophagy to avoid the production of reactive oxygen species. A major signal for the recognition of damaged mitochondria is the electrical membrane potential depolarization, which leads to the recruitment of PTEN-induced putative kinase 1 (PINK1), followed by the recruitment of the E3 ubiquitin ligase parkin at the outer mitochondrial membrane. Parkin ubiquitinates numerous mitochondrial outer membrane proteins and initiates mitophagy. Mutations in the gene encoding parkin are frequently found in familiar forms of Parkinson’s disease. Although several factors involved in parkin mitochondrial recruitment have been characterized, additional proteins may be involved. The aim of this work was to determine whether other factors may be involved in colocalizing parkin to damaged mitochondria. Following up a SILAC-immunoprecipitation experiment, we hypothesized that an unconventional myosin (myosin IIa) may be involved in the recruitment of parkin to the mitochondria. Myosins are a large family of actin-based cytoskeletal motors that use energy derived from ATP hydrolysis to generate movement. Non-conventional myosins are well studied for their contribution to synaptic function in neuronal cells. MYH9 was identified as potential interactor of parkin by mass spectrometry. This interaction was validated through co-immunoprecipitation and immunofluorescence experiments. In addition, myosin alteration with small chemicals that depolymerize actin filament or inhibit myosin activity, impaired parkin localization to mitochondria upon stress. This study potentially implicates myosin IIa as a modulator of parkin recruitment to the mitochondria, and may thus open the door to new therapeutic strategies for Parkinson’s disease.Medicine, Faculty ofBiochemistry and Molecular Biology, Department ofGraduat