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 FK506‐binding protein 51 (FKBP51 or FKBP5), FKBP5 and directly phosphorylates FKBP5 at Serine in an in vitro kinase assay. Both FKBP5 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 FKBP5 using an adeno‐associated virus delivery system negatively regulates AKT phosphorylation at Ser473 in murine‐cultured cortical neurons. Interestingly, FKBP5 over‐expression promotes death in response to MPP+ in the absence of Pink1. Conversely, shRNA‐mediated knockdown of FKBP5 in cultured cortical neurons is protective and this effect is reversed with inhibition of AKT signaling. In addition, shRNA 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 FKBP5 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 FKBP5 interaction with both AKT and PHLPP. Overall, our results suggest a testable model by which Pink1 could regulate AKT through phosphorylation of FKBP5 and interaction of AKT with PHLPP. Our results suggest a potential mechanism by which PINK1‐FKBP5 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/.

Chemical inhibition of FBXO7 reduces inflammation and confers neuroprotection by stabilizing the mitochondrial kinase PINK1

“…In the brain, PINK1 has shown diverse cytoprotective effects. Cellular depletion of PINK1 triggers neuronal cell death, possibly through complex interactions with several client proteins including Akt (14). PINK1 deficiency also leads to reduced dopamine levels, essential for coordinated motor function, and triggers synaptodendritic shrinkage (13,15,16) and the release of inflammatory cytokines such as TNF-α, IL-1β, and COX-2 by astrocytes and microglia, and after injury in the brain (17)(18)(19).…”

The Parkinson's disease gene PINK1 activates Akt via PINK1 kinase-dependent regulation of the phospholipid PI(3,4,5)P3

“…The serine-threonine kinase PINK1 has been extensively investigated since its discovery as an autosomal recessive PDcausing gene (Valente et al, 2004). PINK1 activates and interacts with PI3-kinase-Akt signalling to induce cell survival, mitochondrial integrity and stress resistance (Akundi et al, 2012;Boonying et al, 2019;Contreras-Zárate et al, 2015;Ellis et al, 2013;Hauser et al, 2017;Maj et al, 2010;Mei et al, 2009;Murata et al, 2011;O'Flanagan et al, 2015;O'Flanagan and O'Neill, 2014;Sánchez-Mora et al, 2012;Soutar et al, 2018). Notably, Akt activity is significantly reduced in both in vitro PD models and human dopaminergic substantia nigral neurons in individuals with PD (Malagelada et al, 2008;Timmons et al, 2009).…”

“…While it is clear that PINK1 can activate Akt (Akundi et al, 2012;Boonying et al, 2019;Contreras-Zárate et al, 2015;Ellis et al, 2013;Hauser et al, 2017;Maj et al, 2010;Mei et al, 2009;Murata et al, 2011;O'Flanagan and O'Neill, 2014;Sánchez-Mora et al, 2012;Soutar et al, 2018), and that PINK1 deletion reduces Akt activation, the mechanism by which this occurs and its dependence on PINK1 kinase activity remain unclear. Initial studies revealed that PINK1 markedly enhanced the phosphorylation of Akt at Ser 473 but not Thr 308 , inducing Akt activation that was essential for protection from a variety of cytotoxic agents (Murata et al, 2011).…”

Post-translational modifications and stress adaptation: the paradigm of FKBP51

“…Originally, it was inferred from the pattern of this protein in 2D gel electrophoresis and the modulation of this pattern by the use of kinase inhibitors or phosphatases [40][41][42]. More recently, PTEN-induced putative kinase 1 (PINK1) was found to phosphorylate FKBP51 at yet to be mapped serine residues [43]. Thereby, PINK1 regulates the interaction of FKBP51 with the kinase Akt1 and the phosphatase PHLPP [43].…”

“…More recently, PTEN-induced putative kinase 1 (PINK1) was found to phosphorylate FKBP51 at yet to be mapped serine residues [43]. Thereby, PINK1 regulates the interaction of FKBP51 with the kinase Akt1 and the phosphatase PHLPP [43]. This interaction further is controlled by acetylation of FKBP51 at lysines 28 and 155 [44].…”