Characterization of Tuba, a novel Ena/VASP ligand, and function of Ena/VASP proteins in mouse development

Abstract

Regulated actin assembly drives cells movement, adhesion and shape change. The EnaNASP family of proteins controls actin filament elongation and are important regulators of axon guidance and cell motility. In vertebrates, the family consists of Mena (Mammalian Enabled), VASP (Vasodilator Stimulated Phosphoprotein), and EVL (Ena-VASP-Like). This thesis work focused on understanding the vertebrate EnaNASP protein family by discovering pathways that regulate EnaNASP function and by defining the role of EnaNASP proteins in vertebrate development. Characterization of the EVL locus revealed a new EVL isoform. A protein interaction screen for new EnaNASP ligands produced Tuba, a novel scaffold protein that associates with EnaNASP proteins in vivo. Tuba is a unique guanine nucleotide exchange factor (GEF) for Cdc42 that binds dynamin and a number of actin regulatory proteins in addition to Ena/VASP proteins. A knockout of EVL was made to determine the requirement for EVL in mouse development. Genetic analysis of EnaNASP function in the mouse revealed a requirement for Ena/VASP proteins in neuronal layering, spinal and cranial nerve formation, and cardiovascular development.