Synergistic effects of hmp-2/β-catenin and sma-1/β(H)-spectrin on epidermal morphogenesis in Caenorhabditis elegans

The F-actin, spectrin, and microtubule cytoskeletons are important mediators of embryonic epidermal morphogenesis in Caenorhabditis elegans. While SMA-1/β(H)-spectrin is known to organize actin bundles that connect to cadherin-based adhesions, the role of microtubules in the developing epidermis is not well understood. To determine if the spectrin cytoskeleton also plays a role in organizing epidermal microtubules, we conducted feeding RNA interference of four microtubule-associated protein genes in sma-1/β(H)-spectrin null animals. Knockdown of apr-1, unc-33, unc-44, or cls-1 in sma-1(ru18) homozygotes did not reveal a genetic interaction; however, knockdown of hmp-2/β-catenin in sma-1(ru18) synergistically increased embryonic lethality and epidermal defects.