Abl Interactor 1 (Abi1) and its Interaction with Wiskott Aldrich Syndrome Protein (Wasp) are Critical for Proper Eye Formation in Xenopus Embryos

Abl interactor 1 (Abi1) is a scaffold protein that plays a central role in the regulation of actin cytoskeleton dynamics as a constituent of several key protein complexes, and homozygous loss of this protein leads to embryonic lethality in mice. Since this scaffold protein has been shown in cultured cells to be a critical component of pathways controlling cell migration and actin regulation at cell cell contacts, we were interested to investigate the in vivo role of Abi1 in morphogenesis during the development of Xenopus embryos. Using morpholino-mediated translation inhibition, we demonstrate that knockdown of Abi1 in the whole embryo, or specifically in eye field progenitor cells, leads to disruption of eye morphogenesis. Moreover, signaling through the SH3 domain of Abi1 is critical for proper movement of retinal progenitor cells into the eye field and their appropriate differentiation, and this process is dependent upon an interaction with the nucleation-promoting factor Wasp (Wiskott Aldrich Syndrome Protein). Collectively, our data demonstrate that the Abi1 scaffold protein is an essential regulator of cell movement processes required for normal eye development in Xenopus embryos, and specifically requires a SH3 domain-dependent interaction with Wasp to regulate this complex morphogenetic process.