Pink1 regulates FKBP5 interaction with AKT/PHLPP and protects neurons from neurotoxin stress induced by MPP+

Abstract Loss of function mutations in the PTEN ‐induced putative kinase 1 (Pink1) gene have been linked with an autosomal recessive familial form of early onset Parkinson's disease ( PD ). However, the underlying mechanism(s) responsible for degeneration remains elusive. Presently, using co‐immunoprecipitation in HEK (Human embryonic kidney) 293 cells, we show that Pink1 endogenously interacts with FK 506‐binding protein 51 ( FKBP 51 or FKBP5), FKBP 5 and directly phosphorylates FKBP 5 at Serine in an in vitro kinase assay. Both FKBP 5 and Pink1 have been previously associated with protein kinase B ( AKT ) regulation. We provide evidence using primary cortical cultured neurons from Pink1‐deficient mice that Pink1 increases AKT phosphorylation at Serine 473 (Ser473) challenged by 1‐methyl‐4‐phenylpyridinium ( MPP + ) and that over‐expression of FKBP 5 using an adeno‐associated virus delivery system negatively regulates AKT phosphorylation at Ser473 in murine‐cultured cortical neurons. Interestingly, FKBP 5 over‐expression promotes death in response to MPP + in the absence of Pink1. Conversely, sh RNA ‐mediated knockdown of FKBP 5 in cultured cortical neurons is protective and this effect is reversed with inhibition of AKT signaling. In addition, sh RNA down‐regulation of PH domain leucine‐rich repeat protein phosphatase ( PHLPP ) in Pink1 WT neurons increases neuronal survival, while down‐regulation of PHLPP in Pink1 KO rescues neuronal death in response to MPP + . Finally, using co‐immunoprecipitation, we show that FKBP 5 interacts with the kinase AKT and phosphatase PHLPP . This interaction is increased in the absence of Pink1, both in Mouse Embryonic Fibroblasts ( MEF ) and in mouse brain tissue. Expression of kinase dead Pink1 (K219M) enhances FKBP 5 interaction with both AKT and PHLPP . Overall, our results suggest a testable model by which Pink1 could regulate AKT through phosphorylation of FKBP 5 and interaction of AKT with PHLPP . Our results suggest a potential mechanism by which PINK 1‐ FKBP 5 pathway contributes to neuronal death in PD . Open Science Badges This article has received a badge for * Open Materials * because it provided all relevant information to reproduce the study in the manuscript. The complete Open Science Disclosure form for this article can be found at the end of the article. More information about the Open Practices badges can be found at https://cos.io/our-services/open-science-badges/ . image