page_title: PINK1
section_title: Function
hierarchical_section_title: PINK1 / Function
caption_attribution_description: English: Degradation of damaged mitochondria targeted by PINK1 and parkin
context_page_description: PTEN-induced kinase 1 is a mitochondrial serine/threonine-protein kinase encoded by the PINK1 gene.
  It is thought to protect cells from stress-induced mitochondrial dysfunction. PINK1 activity causes the parkin protein to bind to depolarized mitochondria to induce autophagy of those mitochondria. PINK1 is processed by healthy mitochondria and released to trigger neuron differentiation. Mutations in this gene cause one form of autosomal recessive early-onset Parkinson's disease.
context_section_description: PINK1 is intimately involved with mitochondrial quality control by identifying damaged mitochondria and targeting specific mitochondria for degradation. Healthy mitochondria maintain a membrane potential that can be used to import PINK1 into the inner membrane where it is cleaved by PARL and cleared from the outer membrane. Severely damaged mitochondria lack sufficient membrane potential to import PINK1, which then accumulates on the outer membrane. PINK1 then recruits parkin to target the damaged mitochondria for degradation through autophagy.  Due to the presence of PINK1 throughout the cytoplasm, it has been suggested that PINK1 functions as a "scout" to probe for damaged mitochondria.
  PINK1 may also control mitochondria quality through mitochondrial fission. Through mitochondrial fission, a number of daughter mitochondria are created, often with an uneven distribution in membrane potential. Mitochondria with a strong, healthy membrane potential were more likely to undergo fusion than mitochondria with a low membrane potential. Interference with the mitochondrial fission pathway led to an increase in oxidized proteins and a decrease in respiration. Without PINK1, parkin cannot efficiently localize to damaged mitochondria, while an over-expression of PINK1 causes parkin to localize to even healthy mitochondria.  Furthermore, mutations in both Drp1, a mitochondrial fission factor, and PINK1 were fatal in Drosophila models. However, an over-expression of Drp1 could rescue subjects deficient in PINK1 or parkin, suggesting mitochondrial fission initiated by Drp1 recreates the same effects of the PINK1/parkin pathway.
  In addition to mitochondrial fission, PINK1 has been implicated in mitochondrial motility. The accumulation of PINK1 and recruitment of parkin targets a mitochondria for degradation, and PINK1 may serve to enhance degradation rates by arresting mitochondrial motility. Over-expression of PINK1 produced similar effects to silencing Miro, a protein closely associated with mitochondrial migration.
  Another mechanism of mitochondrial quality control may arise through mitochondria-derived vesicles. Oxidative stress in mitochondria can produce potentially harmful compounds including improperly folded proteins or reactive oxygen species. PINK1 has been shown to facilitate the creation of mitochondria-derived vesicles which can separate reactive oxygen species and shuttle them toward lysosomes for degradation.
caption: A damaged mitochondria being recognized by PINK1. PINK1 builds up on the outer membrane of the mitochondria and recruits parkin. The PINK1/parkin pathway then designates the mitochondria for degradation by lysosomes.
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