Extra-nuclear signaling of estrogen to WAVE1 controls neuronal spine formation through the actin cytoskeleton.

A.M. SANCHEZ; M.I. FLAMINI; A.R. GENAZZANI; T. SIMONCINI

March 4-7, FIRENZE, ITALY.

Congreso; 14th World Congress of Gynecological Endocrinology, II Congresso ISGE Italia; 2010

INTERNATIONAL SOCIETY OF GYNECOLOGICAL ENDOCRINOLOGY (ISGE)

Estrogens are effective regulators of neuronal cell morphology and these actions are thought to be critical for gender-specific differences in brain function and dysfunction. Dendritic spine formation is dependent on actin remodeling by the WASP-family protein, WAVE1, that controls actin polymerization through the actin-related protein 2/3 (Arp2/3) complex. Emerging evidence indicates that estrogens are effective regulators of the actin cytoskeleton in various cell types via rapid, extra-nuclear signaling mechanisms. We here show that 17b-estradiol (E2) administration to rat cortical neurons leads to phosphorylation of WAVE-1 on the serine residues 310, 397 and 441 and to WAVE1 redistribution toward the cell membrane, at sites of dendritic spine formation. WAVE1 phosphorylation is found to be triggered by a G protein-dependent, rapid extra-nuclear signaling of estrogen receptor á (ERá) to c-Src and to the small GTPase Rac1. Rac1 recruits the cyclin-dependent kinase (Cdk5) which directly phosphorylates WAVE1 on the three serine residues. Following WAVE1 phosphorylation by E2, the Arp2/3 complex concentrates at sites of spine formation, where it triggers the local reorganization of actin fibres. Silencing of WAVE1 abrogates the increase in dendritic spines induced by E2. In conclusion, our findings indicate that the control of actin polymerization and branching via WAVE1 is a key function of ER alpha in neurons. The control of WAVE-1 via c-Src, Rac1 and Cdk5 provides a newly identified extra-nuclear mechanism of action of ER alpha, which may be particularly relevant for the regulation of dendritic spines by estrogens in neurons.