IQGAP1 is a scaffolding protein that regulates spine number. We now show a differential role for IQGAP1 domains in spine morphogenesis, in which a region of the N-terminus that promotes Arp2/3-mediated actin polymerization and branching stimulates spine head formation while a region that binds to Cdc42 and Rac is required for stalk extension. Conversely, IQGAP1 rescues spine deficiency induced by expression of dominant negative Cdc42 by stimulating formation of stubby spines. Together, our observations place IQGAP1 as a crucial regulator of spine number and shape acting through the N-Wasp Arp2/3 complex, as well as upstream and downstream of Cdc42.Fil: Jausoro, Ignacio. Consejo Nacional de Invest.cientif.y Tecnicas. Centro Cientifico Tecnol.conicet - Cordoba. Instituto de Inv. Medicas Mercedes y Martin Ferreyra; Universidad Nacional de Cordoba;Fil: Mestres Lascano, Ivan. Consejo Nacional de Invest.cientif.y Tecnicas. Centro Cientifico Tecnol.conicet - Cordoba. Instituto de Inv. Medicas Mercedes y Martin Ferreyra; Universidad Nacional de Cordoba;Fil: Quassollo Infanzon, Gonzalo Emiliano. Consejo Nacional de Invest.cientif.y Tecnicas. Centro Cientifico Tecnol.conicet - Cordoba. Instituto de Inv. Medicas Mercedes y Martin Ferreyra; Universidad Nacional de Cordoba;Fil: Masseroni, Maria Luján. Consejo Nacional de Invest.cientif.y Tecnicas. Centro Cientifico Tecnol.conicet - Cordoba. Instituto de Inv. Medicas Mercedes y Martin Ferreyra; Universidad Nacional de Cordoba;Fil: Heredia, María Florencia. Consejo Nacional de Invest.cientif.y Tecnicas. Centro Cientifico Tecnol.conicet - Cordoba. Instituto de Inv. Medicas Mercedes y Martin Ferreyra; Universidad Nacional de Cordoba;Fil: Caceres, Alfredo Oscar. Consejo Nacional de Invest.cientif.y Tecnicas. Centro Cientifico Tecnol.conicet - Cordoba. Instituto de Inv. Medicas Mercedes y Martin Ferreyra; Universidad Nacional de Cordoba
