Identification and Characterization of Novel Regulators of Cell Invasion in C. elegans

The basement membrane (BM) is a dense, cross-linked extracellular matrix that underlies all epithelial and endothelial cell layers. Cells traverse the BM in a tightly regulated process known as cell invasion, which occurs during specific stages of development such as embryo implantation, or in diseases like metastatic cancers when misregulated. To study BM transmigration in vivo, I used anchor cell (AC) invasion in C. elegans as a model system given its amenability to genetic analysis and live-cell imaging. The AC is a specialized uterine cell that breaches the BMs separating the uterine and vulval tissues in a precise, stereotyped manner during the mid-L3 stage of larval development, allowing for easy identification of mutants with abnormal invasive phenotypes. In C. elegans, this stereotypical process is controlled by specific genetic pathways thought to be initiated with production of FOS-1, the primary regulator of BM removal. However, not all the downstream targets of FOS-1 have been identified to date, leaving gaps in our understanding of the control of the precise steps involved in the AC invasion process. In this study, I identified novel regulators in C. elegans that could address some of the unknown mechanisms involved in AC invasion. Mutants from a pre-existing protruding vulva (Pvl) mutant collection were first screened for a block or delay in AC invasion. Two were identified with phenotypes that were distinct from known genetic mutants, and their associated genes were mapped onto the C. elegans genome. These mutants were then characterized for defining features of BM transmigration, such as changes in actin localization, formation of invadopodia, BM clearance beneath AC, matrix metalloproteinase activity and specification of vulval precursor cell fate, which could allude to their regulatory function in AC invasion. Future work will focus more specifically on demonstrating the role of these novel regulators within known pathways.