DepartmentMolecular Cell Biology
Publication date11-jan-2007

Yohei Sasagawa, Shusei Sato, Teru Ogura, and Atsushi Higashitani (2007) C. elegans RBX-2-CUL-5- and RBX-1-CUL-2-based complexes are redundant for oogenesis and activation of the MAP kinase MPK-1. FEBS Lett. 581, 145-150.

Cul5-based complex is a member of ECS (Elongin B/C-Cul2/Cul5-SOCS-box protein) ubiquitin ligase family. The cellular function of the Cul5-based complex is poorly understood. In this study, we found that oocyte septum formation and egg production did not occur in either cul-5- or rbx-2- depleted cul-2 homozygotes, although control cul-2 homozygotes laid approximately 50 eggs. These phenotypes are reminiscent of those caused by the MAP kinase mpk-1 depletion. In fact, activation of MPK-1 was significantly inhibited in cul-5- depleted cul-2 mutant and cul-2- depleted cul-5 mutant. Yeast two-hybrid analysis and RNAi-knockdown experiments suggest that oocyte maturation from pachytene exit and MPK-1 activation are redundantly controlled by the RBX-2-CUL-5- and RBX-1-CUL-2-based complexes.



Figure: CUL-5 is required for phosphorylation of the MAP kinase MPK-1 in the germline. Each gonad was dissected from each RNAi treated worms and stained with anti-diphospho-MPK-1 and anti-unphosphorylated-MPK-1 antibodies. White arrows indicate pachytene regions lacking nuclei. White lines indicate other regions lacking nuclei. Bars represent 50 micrometers. The signal specific to diphosphorylated MPK-1 is significantly reduced in cul-2 worms subjected to cul-5 RNAi and in wild-type worms subjected to mpk-1 RNAi. However, the unphosphorylated MPK1-specific signal is unaffected in cul-2 worms subjected to cul-5 RNAi.