An endogenous PI3K interactome promoting astrocyte-mediated neuroprotection identifies a novel association with RNA-binding protein ZC3H14

• Type of Material: Article
• Authors: Samih Alqawlaq, University Health Network, Toronto; Izhar Livne-Bar, University Health Network, Toronto; Declan Williams, University of Toronto; Joseph D'Ercole, University Health Network, Toronto; Sara Leung, Emory University; Darren Chan, University Health Network, Toronto; Alessandra Tuccitto, University Health Network, Toronto; Alessandro Datti, Mount Sinai Hospital, Toronto; Jeffrey L Wrana, Mount Sinai Hospital, Toronto; Anita Corbett, Emory University; Gerold Schmitt-Ulms, University of Toronto; Jeremy M Sivak, University Health Network, Toronto
• Language: English
• Date: 2021-01-01
• Publisher: ELSEVIER
• Publication Version: Final Published Version
• Copyright Statement: © 2020 THE AUTHORS
• License: Creative Commons Attribution 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1074/jbc.RA120.015389
• Title of Journal or Parent Work: JOURNAL OF BIOLOGICAL CHEMISTRY
• Volume: 296
• Start Page: 100118
• End Page: 100118
• Grant/Funding Information: This work was supported by CIHR grants MOP123448 and PJT168845, NSERC grant RGPIN-2015-06561 (J. M. S.), and National Institutes of Health R01 grants MH107305 and GM130147 (A. H. C.). J. M. S. holds the TWGH Foundation Glaucoma Research Chair. S. A. was supported by a Vision Science Research Program (VSRP) fellowship. The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health.
• Keywords: OPTIC-NERVE; Life Sciences & Biomedicine; EXPRESSION; GANGLION-CELL NEUROPROTECTION; PDGF; SIGNALING PATHWAY; POLYADENOSINE RNA; Science & Technology; INHIBITOR; Biochemistry & Molecular Biology; MECHANISMS; GROWTH-FACTOR; ACTIVATION
• Research Categories: Biology, General; Health Sciences, Opthamology

Abstract

Astrocytes can support neuronal survival through a range of secreted signals that protect against neurotoxicity, oxidative stress, and apoptotic cascades. Thus, analyzing the effects of the astrocyte secretomemay provide valuable insight into these neuroprotective mechanisms. Previously, we characterized a potent neuroprotective activitymediated by retinal astrocyte conditionedmedia (ACM) on retinal and cortical neurons in metabolic stressmodels. However, the molecular mechanism underlying this complex activity in neuronal cells has remained unclear. Here, a chemical genetics screen of kinase inhibitors revealed phosphoinositide 3-kinase (PI3K) as a central player transducing ACM-mediated neuroprotection. To identify additional proteins contributing to the protective cascade, endogenous PI3Kwas immunoprecipitated fromneuronal cells exposed toACMor controlmedia, followed by MS/MS proteomic analyses.These data pointed toward a relatively small number of proteins that coimmunoprecipitated with PI3K, and surprisingly only five were regulated by theACMsignal. These hits included expected PI3K interactors, such as the plateletderived growth factor receptor A (PDGFRA), as well as novel RNA-binding protein interactors ZC3H14 (zinc fingerCCCH-Type containing 14) and THOC1 (THO complex protein 1). In particular, ZC3H14 has recently emerged as an important RNA-binding protein with multiple roles in posttranscriptional regulation. In validation studies, we show that PI3K recruitment of ZC3H14 is necessary for PDGF-induced neuroprotection and that this interaction is present in primary retinal ganglion cells. Thus, we identified a novel non cell autonomous neuroprotective signaling cascade mediated through PI3K that requires recruitment of ZC3H14 and may present a promising strategy to promote astrocyte-secreted prosurvival signals.