Epithelial cells, which line our organs, possess adhesive junctions that enable them to function as a barrier to the outside environment. Loss of junctions compromises tissue structure and has been linked to human diseases such as kidney disease, cancer, and birth defects. Junctions form when clusters of junction proteins concentrate at cell contacts near the apical surface then coalesce into belt-like structures. The atypical protein kinase C (aPKC), which functions together with the scaffolding protein PAR-6, is required for junction formation in other species, although its regulators and targets important for junction formation are incompletely understood. We are using C. elegans as a model to understand how aPKC regulates epithelial cell junctions. Using a targeted protein degradation strategy, we first demonstrated that C. elegans PKC-3/aPKC, like PAR-6, is required for junction maturation. A hypomorphic temperature-sensitive allele of pkc-3 causes junction breaks in the spermatheca, a mechanically active organ, leading to sterility. We used this allele in a suppressor screen to find genes that may function with pkc-3 in regulating junctions. We identified multiple intragenic mutations in the pkc-3 gene, including an unexpected stop-to-stop mutation, demonstrating the specificity of the screen. Extragenic suppressors included an allele of the lethal giant larvae gene lgl-1, which antagonizes aPKC in other systems but was not known previously to function in C. elegans epithelia. Finally, we identified two alleles of a previously uncharacterized gene, sups-1, which encodes an extracellular protein expressed in epidermal cells that localizes to the apical ECM. Our findings define new genes involved in epithelial junction formation in C. elegans and indicate the surprising role that stop codon choice can have on gene activity.
|Advisor:||Nance, Jeremy F.|
|Commitee:||Treisman, Jessica, Ringstad, Niels, Siegal, Mark, Soto, Martha|
|School:||New York University|
|Department:||Basic Medical Science|
|School Location:||United States -- New York|
|Source:||DAI-B 81/5(E), Dissertation Abstracts International|
|Subjects:||Developmental biology, Genetics|
|Keywords:||Adherens junction, aPKC, C. elegans, Epithelia, Stop codon, Suppressor|
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