PINK1 phosphorylates Drp1^S616 to regulate mitophagy-independent mitochondrial dynamics

Impairment of PINK1/parkin-mediated mitophagy is currently proposed to be the molecular basis of mitochondrial abnormality in Parkinson's disease (PD). We here demonstrate that PINK1 directly phosphorylates Drp1 on S616. Drp1^S616 phosphorylation is significantly reduced in cells and mouse tissues deficient for PINK1, but unaffected by parkin inactivation. PINK1-mediated mitochondrial fission is Drp1^S616 phosphorylation dependent. Overexpression of either wild-type Drp1 or of the phosphomimetic mutant Drp1^S616D, but not a dephosphorylation-mimic mutant Drp1^S616A, rescues PINK1 deficiency-associated phenotypes in Drosophila. Moreover, Drp1 restores PINK1-dependent mitochondrial fission in ATG5-null cells and ATG7-null Drosophila. Reduced Drp1^S616 phosphorylation is detected in fibroblasts derived from 4 PD patients harboring PINK1 mutations and in 4 out of 7 sporadic PD cases. Taken together, we have identified Drp1 as a substrate of PINK1 and a novel mechanism how PINK1 regulates mitochondrial fission independent of parkin and autophagy. Our results further link impaired PINK1-mediated Drp1^S616 phosphorylation with the pathogenesis of both familial and sporadic PD.