Wnt Signaling in Cellular Motility

Rutgers, The State University Of New Jersey-Rbhs-Robert Wood, Piscataway NJ

Investigators

Abstract

0544061. Habas. Wnt proteins represent a family of conserved secreted glycoproteins that play critical roles in embryonic development. One important effect of Wnt signaling occurs via the non-canonical Wnt signaling pathway that results in dramatic changes to the actin cytoskeleton required for cellular polarization and motility during vertebrate gastrulation and neural fold closure. However, how the non-canonical Wnt pathway regulates changes to the actin cytoskeleton remains poorly defined. Studies by Dr. Habas have identified the Formin-homology protein Daam1 as a crucial link between Dishevelled and the small GTPase Rho in mediating changes to the actin cytoskeleton for non-canonical Wnt signaling. But how this protein mediates its effects on the actin cytoskeleton remains poorly understood. In a screen for effectors of Daam1, he has isolated Profilin2 as a factor that binds to Daam1 and modulates non-canonical Wnt signaling. Profilin2 has been shown to influence actin polymerization and can thus function as an important and direct link from Daam1 to the actin cytoskeleton. He has begun to examine the in-vivo role of Profilin2 during Xenopus development and observe overexpression or depletion of Profilin2 inhibits gastrulation and neural fold closure resulting in a spina bifida phenotype. He hypothesizes that Profilin2 is a major factor required for Wnt-mediated cytoskeletal modulation and cellular motility during vertebrate gastrulation and neural fold closure. The proposed experiments are directed towards the characterization of the role of Profilin2 in Wnt signal transduction. He will utilize a multidisciplinary approach drawing the laboratory's strengths and experience in biochemistry, cell biology and embryology to elucidate the function of this molecule for non-canonical signaling with the following goals (1) mutational analysis of the regions of Daam1 required for binding to Profilin2, (2) determining the effects of Profilin2 on convergent extension movements and mesoderm specification in Xenopus and (3) determining the requirement of Profilin2 in Xenopus in gastrulation, blastophore closure and neural fold closure. The proposed studies will not only reveal how non-canonical Wnt signaling mediated through Daam1 and Profilin2 exerts regulates vertebrate morphogenesis but will uncover the mechanisms by which such effects are accomplished. These studies will also deepen our understanding of how Wnt signaling impacts cellular morphology, a process deregulated in cancer metastasis. Importantly, a post-doctoral fellow as well as minority graduate students and undergraduate students will perform the studies presented in this grant. Thus, they will serve an important basis for the training of the next generation of scientists in a multidisciplinary approach to the basic sciences.