Implicating SCF Complexes in Organogenesis in Caenorhabditis elegans
Stanley R. G. Polley, Aleksandra Kuzmanov, Jujiao Kuang, Jonathan Karpel, Vladimir Lažetić, Evguenia I. Karina, Bethany L. Veo, David S. Fay

Abstract

Development of the Caenorhabditis elegans foregut (pharynx) is regulated by a network of proteins that includes the Retinoblastoma protein (pRb) ortholog LIN-35, the ubiquitin pathway components UBC-18 and ARI-1, and by PHA-1, a cytoplasmic protein. Loss of pha-1 activity impairs pharyngeal development and body morphogenesis, leading to embryonic arrest. We have used a genetic suppressor approach to dissect this complex pathway. The lethality of pha-1 mutants is suppressed by loss-of-function mutations in sup-35/ztf-21 and sup-37/ztf-12, which encode Zn-finger proteins, and by mutations in sup-36. Here we show that sup-36 encodes a divergent Skp1 family member that binds to several F-box proteins and the microtubule-associated protein PTL-1/tau. Like SUP-35, SUP-36 levels were negatively regulated by UBC-18–ARI-1. We also found that SUP-35 and SUP-37 physically associated and that SUP-35 could bind microtubules. Thus, SUP-35, SUP-36, and SUP-37 may function within a pathway or complex that includes cytoskeletal components. Additionally, SUP-36 may regulate the subcellular localization of SUP-35 during embryogenesis. We carried out a genome-wide RNAi screen to identify additional regulators of this network and identified 39 genes, most of which are associated with transcriptional regulation. Twenty-three of these genes acted via the LIN-35 pathway. In addition, several Skp1-Cullin-F-Box (SCF) components were identified, further implicating SCF complexes as part of the greater network controlling pharyngeal development.

  • Received April 23, 2013.
  • Accepted October 29, 2013.