title: P-Rex1 - a multidomain protein that regulates neurite differentiation.
abstract: The Rac-GEF P-Rex1 promotes membrane ruffling and cell migration in response to Rac activation, but its role in neuritogenesis is unknown. Rac1 promotes neurite differentiation; Rac3, however, may play an opposing role. Here we report that in nerve growth factor (NGF)-differentiated rat PC12 cells, P-Rex1 localised to the distal tips of developing neurites and to the axonal shaft and growth cone of differentiating hippocampal neurons. P-Rex1 expression inhibited NGF-stimulated PC12 neurite differentiation and this was dependent on the Rac-GEF activity of P-Rex1. P-Rex1 inhibition of neurite outgrowth was rescued by low-dose cytochalasin D treatment, which prevents actin polymerisation. P-Rex1 activated Rac3 GTPase activity when coexpressed in PC12 cells. In the absence of NGF stimulation, targeted depletion of P-Rex1 in PC12 cells by RNA interference induced the spontaneous formation of beta-tubulin-enriched projections. Following NGF stimulation, enhanced neurite differentiation, with neurite hyper-elongation correlating with decreased F-actin at the growth cone, was demonstrated in P-Rex1 knockdown cells. Interestingly, P-Rex1-depleted PC12 cells exhibited reduced Rac3 and Rac1 GTPase activity. This study has identified P-Rex1 as a Rac3-GEF in neuronal cells that localises to, and regulates, actin cytoskeletal dynamics at the axonal growth cone to in turn regulate neurite differentiation.
authors.affiliation: Department of Biochemistry and Molecular Biology, Monash University, Clayton 3800, Victoria, Australia.
authors.forename: Joanne E
authors.initials: JE
authors.lastname: Waters
authors.forename: Megan V
authors.initials: MV
authors.lastname: Astle
authors.forename: Lisa M
authors.initials: LM
authors.lastname: Ooms
authors.forename: Demis
authors.initials: D
authors.lastname: Balamatsias
authors.forename: Rajendra
authors.initials: R
authors.lastname: Gurung
authors.forename: Christina A
authors.initials: CA
authors.lastname: Mitchell
mesh_terms: D000818:Animals; D002454:Cell Differentiation / Q000187:drug effects; D004789:Enzyme Activation / Q000187:drug effects; D020439:Growth Cones / Q000187:drug effects / Q000378:metabolism; D020662:Guanine Nucleotide Exchange Factors / Q000737:chemistry / Q000378:metabolism*; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism; D006801:Humans; D020932:Nerve Growth Factor / Q000494:pharmacology; D016501:Neurites / Q000187:drug effects / Q000378:metabolism*; D016716:PC12 Cells; D017434:Protein Structure, Tertiary; D021381:Protein Transport / Q000187:drug effects; D034622:RNA Interference / Q000187:drug effects; D051381:Rats; D017207:Rats, Sprague-Dawley; D020744:rac GTP-Binding Proteins / Q000378:metabolism
chemical_list: D020662:Guanine Nucleotide Exchange Factors; C453280:PREX1 protein, human; C532509:Prex1 protein, rat; D020932:Nerve Growth Factor; D020744:rac GTP-Binding Proteins