title: Protein kinase C-dependent growth-associated protein 43 phosphorylation regulates gephyrin aggregation at developing GABAergic synapses.
abstract: Growth-associated protein 43 (GAP43) is known to regulate axon growth, but whether it also plays a role in synaptogenesis remains unclear. Here, we found that GAP43 regulates the aggregation of gephyrin, a pivotal protein for clustering postsynaptic GABA(A) receptors (GABA(A)Rs), in developing cortical neurons. Pharmacological blockade of either protein kinase C (PKC) or neuronal activity increased both GAP43-gephyrin association and gephyrin misfolding-induced aggregation, suggesting the importance of PKC-dependent regulation of GABAergic synapses. Furthermore, we found that PKC phosphorylation-resistant GAP43(S41A), but not PKC phosphorylation-mimicking GAP43(S41D), interacted with cytosolic gephyrin to trigger gephyrin misfolding and its sequestration into aggresomes. In contrast, GAP43(S41D), but not GAP43(S41A), inhibited the physiological aggregation/clustering of gephyrin, reduced surface GABA(A)Rs under physiological conditions, and attenuated gephyrin misfolding under transient oxygen-glucose deprivation (tOGD) that mimics pathological neonatal hypoxia. Calcineurin-mediated GAP43 dephosphorylation that accompanied tOGD also led to GAP43-gephyrin association and gephyrin misfolding. Thus, PKC-dependent phosphorylation of GAP43 plays a critical role in regulating postsynaptic gephyrin aggregation in developing GABAergic synapses.
authors.affiliation: Department and Institute of Physiology and Brain Research Center, National Yang-Ming University, Taipei, Taiwan Graduate Institute of Medical Sciences, Taipei Medical University, Taipei, Taiwan Graduate Institute of Clinical Medical Science and Department of Neurology, China Medical University and Hospital, Taichung, Taiwan.
authors.forename: Chen-Yu
authors.initials: CY
authors.lastname: Wang
authors.affiliation: Department and Institute of Physiology and Brain Research Center, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Hui-Ching
authors.initials: HC
authors.lastname: Lin
authors.affiliation: Graduate Institute of Medical Sciences, Taipei Medical University, Taipei, Taiwan.
authors.forename: Yi-Ping
authors.initials: YP
authors.lastname: Song
authors.affiliation: Graduate Institute of Medical Sciences, Taipei Medical University, Taipei, Taiwan.
authors.forename: Yu-Ting
authors.initials: YT
authors.lastname: Hsu
authors.affiliation: Common Mass Spectrometry Facilities at Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan.
authors.forename: Shu-Yu
authors.initials: SY
authors.lastname: Lin
authors.affiliation: Department and Institute of Physiology and Brain Research Center, National Yang-Ming University, Taipei, Taiwan.
authors.forename: Pei-Chien
authors.initials: PC
authors.lastname: Hsu
authors.affiliation: Nursing, Kang-Ning Junior College of Medical Care and Management, Taipei, Taiwan.
authors.forename: Chun-Hua
authors.initials: CH
authors.lastname: Lin
authors.affiliation: Department and Institute of Physiology and Brain Research Center, National Yang-Ming University, Taipei, Taiwan Graduate Institute of Medical Sciences, Taipei Medical University, Taipei, Taiwan.
authors.forename: Chia-Chi
authors.initials: CC
authors.lastname: Hung
authors.affiliation: Graduate Institute of Medical Sciences, Taipei Medical University, Taipei, Taiwan.
authors.forename: Min-Ching
authors.initials: MC
authors.lastname: Hsu
authors.affiliation: Department and Institute of Physiology and Brain Research Center, National Yang-Ming University, Taipei, Taiwan Department of Anesthesiology, Taipei Veterans General Hospital and National Yang-Ming University, Taipei, Taiwan.
authors.forename: Yi-Min
authors.initials: YM
authors.lastname: Kuo
authors.affiliation: School of Medicine, Fu-Jen Catholic University, New Taipei City, Taiwan.
authors.forename: Yih-Jing
authors.initials: YJ
authors.lastname: Lee
authors.affiliation: Graduate Institute of Clinical Medical Science and Department of Neurology, China Medical University and Hospital, Taichung, Taiwan.
authors.forename: Chung Y
authors.initials: CY
authors.lastname: Hsu
authors.affiliation: Department and Institute of Physiology and Brain Research Center, National Yang-Ming University, Taipei, Taiwan Graduate Institute of Medical Sciences, Taipei Medical University, Taipei, Taiwan yhlee3@ym.edu.tw.
authors.forename: Yi-Hsuan
authors.initials: YH
authors.lastname: Lee
mesh_terms: D000818:Animals; D002352:Carrier Proteins / Q000737:chemistry / Q000378:metabolism*; D002478:Cells, Cultured; D005260:Female; D005419:Flavonoids / Q000494:pharmacology; D059330:GABAergic Neurons / Q000166:cytology / Q000378:metabolism*; D019922:GAP-43 Protein / Q000737:chemistry / Q000378:metabolism*; D057809:HEK293 Cells; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism*; D010766:Phosphorylation; D011247:Pregnancy; D017510:Protein Folding / Q000187:drug effects; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D002352:Carrier Proteins; D005419:Flavonoids; D019922:GAP-43 Protein; D007211:Indoles; D008565:Membrane Proteins; C073441:gephyrin; D011493:Protein Kinase C; C093973:2-(2-amino-3-methoxyphenyl)-4H-1-benzopyran-4-one; C064758:Ro 31-8220