title: The mental retardation associated protein, srGAP3 negatively regulates VPA-induced neuronal differentiation of Neuro2A cells.
abstract: The Slit-Robo GTPase-activating proteins (srGAPs) are important multifunctional adaptor proteins involved in various aspects of neuronal development, including axon guidance, neuronal migration, neurite outgrowth, dendritic morphology and synaptic plasticity. Among them, srGAP3, also named MEGAP (Mental disorder-associated GTPase-activating protein), plays a putative role in severe mental retardation. SrGAP3 expression in ventricular zones of neurogenesis indicates its involvement in early stage of neuronal development and differentiation. Here, we show that overexpression of srGAP3 inhibits VPA (valproic acid)-induced neurite initiation and neuronal differentiation in Neuro2A neuroblastoma cells, whereas knockdown of srGAP3 facilitates the neuronal differentiation in this cell line. In contrast to the wild type, overexpression of srGAP3 harboring an artificially mutation R542A within the functionally important RhoGAP domain does not exert a visible inhibitory effect on neuronal differentiation. The endogenous srGAP3 selectively binds to activated form of Rac1 in a RhoGAP pull-down assay. We also show that constitutively active (CA) Rac1 can rescue the effect of srGAP3 on attenuating neuronal differentiation. Furthermore, change in expression and localization of endogenous srGAP3 is observed in neuronal differentiated Neuro2A cells. Together, our data suggest that srGAP3 could regulate neuronal differentiation in a Rac1-dependent manner.
authors.affiliation: Institute of Neurosciences, School of Life Sciences and Biotechnology, Shanghai Jiao Tong University, China.
authors.forename: Keng
authors.initials: K
authors.lastname: Chen
authors.forename: Ya-Jing
authors.initials: YJ
authors.lastname: Mi
authors.forename: Yue
authors.initials: Y
authors.lastname: Ma
authors.forename: Hua-Lin
authors.initials: HL
authors.lastname: Fu
authors.forename: Wei-Lin
authors.initials: WL
authors.lastname: Jin
mesh_terms: D000818:Animals; D000906:Antibodies / Q000276:immunology; D000918:Antibody Specificity / Q000187:drug effects / Q000276:immunology; D002454:Cell Differentiation / Q000187:drug effects*; D045744:Cell Line, Tumor; D020690:GTPase-Activating Proteins / Q000378:metabolism*; D055785:Gene Knockdown Techniques; D049452:Green Fluorescent Proteins / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D008607:Intellectual Disability / Q000378:metabolism*; D051379:Mice; D009474:Neurons; D013347:Subcellular Fractions / Q000187:drug effects / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects; D014635:Valproic Acid / Q000494:pharmacology*; D020830:rac1 GTP-Binding Protein / Q000378:metabolism
chemical_list: D000906:Antibodies; D020690:GTPase-Activating Proteins; C516731:Srgap3 protein, mouse; C485184:enhanced green fluorescent protein; D049452:Green Fluorescent Proteins; D014635:Valproic Acid; D020830:rac1 GTP-Binding Protein