Negative feedback by conserved kinases patterns the degradation of Caenorhabditiselegans Raf in vulval fate...

Area of Science:

• Developmental Biology
• Cell Signaling
• Molecular Genetics

Background:

• The epidermal growth factor receptor (EGFR)-Ras-Raf-ERK pathway patterns Caenorhabditis elegans vulval precursor cells (VPCs).
• MPK-1/ERK activity targets LIN-45/Raf for degradation via SEL-10/FBXW7 E3 ubiquitin ligase, involving a conserved Cdc4 phosphodegron (CPD).

Purpose of the Study:

• To identify and characterize the minimal degron responsible for SEL-10-mediated, MPK-1-dependent LIN-45/Raf degradation.
• To elucidate the roles of conserved kinases in regulating LIN-45/Raf turnover during VPC patterning.

Main Methods:

• Targeted genetic screen of conserved protein kinase-encoding genes.
• Genetic analysis of LIN-45 degradation during C. elegans larval development.
• Investigating the spatial and temporal control of LIN-45/Raf degradation.

Main Results:

• Identified GSK-3 and CDK-2 as essential for LIN-45 degron-mediated turnover.
• LIN-45 degradation is blocked during the second larval stage due to cell cycle quiescence and requires CDK activation for relief in the third larval stage.
• MPK-1 activation spatially patterns LIN-45 degradation but does not bypass the need for GSK-3 and CDK-2.

Conclusions:

• MPK-1/ERK, GSK-3, CDK-2, and SEL-10/FBXW7 form a regulatory network controlling LIN-45/Raf degradation.
• This network provides spatial and temporal regulation of LIN-45/Raf turnover essential for VPC patterning.