Characterization of the fhod-2 gene in Caenorhabditis elegans

Abstract

Formins are a family of proteins responsible for a vast array of cellular functions such as cell shape, adhesion, cytokinesis and morphogenesis. Formin regulation of actin is a highly regulated process and is conserved from yeast to mammalian systems. Previous studies have shown that formins alone are necessary and sufficient for proper recruitment, polymerization and nucleation of actin filaments in the cell. The Chin-Sang lab is interested in studying development in C. elegans. In particular, one area of our research focuses on trying to understand different pathways and their related genes that ultimately determine cell shape changes and cell movements. This is an important area of research as many genes found in C. elegans have homologous counterparts in the human system. Studying these simple nematode worms may provide us insight into how the much more complex human body functions. Ultimately, research may provide clues or strategies for future treatments such as gene therapy. The focus of my research is on the fhod-2 gene. fhod-2 (Formin HOmology Domain) is a member of the formin family. Our lab has previously shown that this gene may be involved in early embryo development. Through characterization of a fhod-2 deletion mutant, I have been able to further elaborate on this work. Through the use of over-expressing lines, RNAi, protein expression and DIC microscopy I have identified defects caused by this mutation. fhod-2 is necessary for a variety of cellular functions both early in the embryo and later for proper development of the organism. FHOD-2 in situ antibody staining revealed expression in the pharynx and leading/seam cells, western blots of FHOD-2 over-expressing lines also detect higher amounts of FHOD-2 protein in embryos suggesting an embryonic function. I have provided evidence that fhod-2 is a maternal effect lethal gene with defects seen in cytokinesis, gastrulation and elongation. DIC imaging of maternally rescued fhod-2 mutants reveal a plethora of defects affecting the head, gonad and excretory canal cell. Lastly through the use of florescence reporter constructs, fhod-2 mutants have neuronal defects displaying over-extension, early termination or branching of neurites.