PTEN-induced kinase 1 and Parkin pathway (PINK1/Parkin pathway)

The PINK1/Parkin pathway refers to the coordinated action between PTEN-induced kinase 1 (PINK1)—a mitochondrial serine/threonine-protein kinase—and Parkin, an E3 ubiquitin ligase. This signaling axis plays a central role in maintaining mitochondrial integrity through selective autophagic removal ("mitophagy") of damaged mitochondria. Under normal conditions, PINK1 is imported into healthy mitochondria where it is rapidly degraded. When mitochondria become depolarized or dysfunctional, PINK1 accumulates on the outer membrane where it becomes activated through autophosphorylation. Activated PINK1 then phosphorylates both ubiquitin molecules on the outer membrane proteins and the Ubl domain of cytosolic Parkin, triggering conformational changes that recruit and activate Parkin at the site. Once recruited, active Parkin ubiquitylates numerous outer mitochondrial membrane proteins with various types of polyubiquitin chains—a process that flags these organelles for recognition by autophagic machinery leading to their degradation within lysosomes. This mechanism serves as a critical quality-control process protecting neurons from stress-induced cell death due to accumulation of defective mitochondria. Mutations in either PINK1 or Park2 (Parkin) genes cause autosomal recessive early-onset Parkinson’s disease due to failure in this protective mitophagy mechanism. The search for small-molecule activators has identified compounds such as kinetin riboside derivatives and niclosamide as potential pharmacological tools but no approved therapies exist yet targeting this axis directly. In summary, the PINK1/Parkin pathway represents an essential enzymatic signaling cascade regulating neuronal health via targeted clearance of dysfunctional mitochondria—a validated therapeutic target especially relevant in neurodegenerative diseases like Parkinson's disease.

Other names

PINK1-Parkin pathwayPTEN-induced putative kinase 1 and Parkin pathwayMitochondrial quality control pathway (context-dependent)

Activation of mitophagy via phosphorylation of ubiquitin and Parkin by PINK1, leading to recruitment of Parkin to depolarized mitochondria for ubiquitylation and subsequent autophagic degradation.