Distinct modes of DLC1 function regulate avian cranial neural crest cell fate commitment and delamination

Abstract

During embryogenesis, an epithelial to mesenchymal transition (EMT) is a crucial biological process that contribute to the formation of various cell types. These events have been well-studied in a highly migratory population of embryonic stem cell-like population, neural crest cells which differentiate into different derivatives throughout the body. Dlc1 is a multi-domain protein which contains the sterile α motif (SAM), the FAT (focal adhesion targeting region), the RhoGAP and the START domains. We previously demonstrated that Dlc1 is crucial for trunk neural crest directional migration but its expression in presumptive and early migratory cranial neural crest cells prompts us to hypothesize that Dlc1 also plays a role during early cranial neural crest development. Thus, we undertook a structural-functional analyses using full length Dlc1 and various truncated constructs to dissect the mode of action of DLC1 during cranial neural crest specification and delamination. Here we reveal the amino-terminal portion of Dlc1 without RhoGAP and START domains regulates Snail2 stability via modulating the activity of GSK3beta in the cytosol that allows proper onset of neural crest delamination. In contrast, the carboxyl-terminal portion of Dlc1 is required for the maintenance of neural crest specifier genes expression in the nucleus. In addition, we found the RhoGAP domain of Dlc1 is mainly responsible for the cranial neural crest specification, and directional delamination and migration. Altogether, our findings reveal distinct modes of Dlc1 function regulate avian cranial neural crest cell fate commitment and delamination.