Accumulation of dysfunctional Mitochondria has been implicated in the pathogenesis of Parkinson's disease (PD). Mutations in PTEN-induced kinase 1 (PINK1), which encodes a putative mitochondrial serine/threonine kinase, have been identified in early-onset forms of PD. Recent data showed that the loss of PINK1 function led to oxidative stress, mitochondrial damage and autophagic elimination of damaged mitochondria. But the precise mechanism of autophagy induced by loss of PINK1 is unclear. In this study, we found that in mouse dopaminergic MN9D cells, down-regulation of PINK1 by RNA interference resulted in induction of mitochondrial autophagy (mitophagy), abnormal mitochondrial morphology, partial loss of mitochondrial membrane potential and increased production of reactive oxygen species (ROS). Mitophagy in these cells was associated with the up-regulation of autophagy activator Beclin 1 and opening of mitochondrial permeability transition (MPT) pore. These findings suggest that PINK1 may regulate mitophagy through controlling MPT pore opening and general autophagy regulators. (C) 2011 Published by Elsevier By.