PINK1 Protects against Oxidative Stress by Phosphorylating Mitochondrial Chaperone TRAP1

Abstract

Mutations in the PTEN induced putative kinase 1 (PINK1) gene cause an autosomal recessive form of Parkinson disease (PD). So far, no substrates of PINK1 have been reported, and the mechanism by which PINK1 mutations lead to neurodegeneration is unknown. Here we report the identification of TNF receptor-associated protein 1 (TRAP1), a mitochondrial molecular chaperone also known as heat shock protein 75 (Hsp75), as a cellular substrate for PINK1 kinase. PINK1 binds and colocalizes with TRAP1 in the mitochondria and phosphorylates TRAP1 both in vitro and in vivo. We show that PINK1 protects against oxidative-stress-induced cell death by suppressing cytochrome c release from mitochondria, and this protective action of PINK1 depends on its kinase activity to phosphorylate TRAP1. Moreover, we find that the ability of PINK1 to promote TRAP1 phosphorylation and cell survival is impaired by PD-linked PINK1 G309D, L347P, and W437X mutations. Our findings suggest a novel pathway by which PINK1 phosphorylates downstream effector TRAP1 to prevent oxidative-stress-induced apoptosis and implicate the dysregulation of this mitochondrial pathway in PD pathogenesis. Parkinson disease (PD) is characterized by the selective loss of midbrain dopaminergic neurons. Although the cause of PD is unknown, pathological analyses have suggested the involvement of oxidative stress and mitochondrial dysfunction. Recently, an inherited form of early-onset PD has been linked to mutations in both copies of the gene encoding the mitochondrial protein PINK1. Furthermore, increasing evidence indicates that single-copy mutations in PINK1 are a significant risk factor in the development of later-onset PD. Here we show that PINK1 is a protein kinase that phosphorylates the mitochondrial molecular chaperone TRAP1 to promote cell survival. We find that PINK1 normally protects against oxidative-stress-induced cell death by suppressing cytochrome c release from mitochondria. The PINK1 mutations linked to PD impair the ability of PINK1 to phosphorylate TRAP1 and promote cell survival. Our findings reveal a novel anti-apoptotic signaling pathway that is disrupted by mutations in PINK1. We suggest that this pathway has a role in PD pathogenesis and may be a target for therapeutic intervention.