Microtubules and fertilization: The MEI-1/Katanin mediated cytoskeletal transition from meiosis to mitosis in the developing C. elegans embryo

Abstract

During embryonic development, dramatic changes of the C. elegans cytoskeleton occur in the transition from the meiosis to mitosis requiring precise regulation of molecules specific to each type of spindle. The microtubule severing complex, MEI-1/MEI-2, is required for C. elegans meiotic spindle formation, but must be inactivated to prevent disruption of mitosis. There are several redundant pathways involved in this tightly regulated process. In order to determine how known genes of these pathways function relative to one another, I have developed a robust antibody-staining assay to measure anti-MEI-1 protein levels based on total pixel intensity in early embryogenesis. Using this assay, I have shown that APC and MBK-2 act strictly sequentially with one another to degrade MEI-1. I have also shown that ectopic MEI-1 staining in cul-2 and rfl-1 are enhanced by mel-26 and not by mbk-2 indicating that CUL-2 and MBK-2 are working together to degrade MEI-1 in parallel to the MEL-26/CUL-2 pathway and that RFL-1 is activating CUL-2 in this process. hecd-1 ectopic MEI-1 staining was not enhanced by any of the known regulatory genes in this process and might be inhibiting an activator of MEI-1. This project will assist in decoding the key regulatory molecules of the developmental remodelling in early embryos.