RET modulates cell adhesion via its cleavage by caspase in sympathetic neurons

Abstract

RET is a tyrosine kinase receptor involved in numerous cellular mechanisms including proliferation, neuronal navigation, migration, and differentiation upon binding with glial cell derived neurotrophic factor family ligands. RET is an atypical tyrosine kinase receptor containing four cadherin domains inits extracellular part. Furthermore, it has been shown to act as a dependence receptor. Such a receptor is active in the absence of ligand, triggering apoptosis through a mechanism that requires receptor intracellular caspase cleavage. However, different data suggest that RET is not always associated with the cell death/survival balance but rather provides positional information. We demonstrate here that caspase cleav age of RET is involved in the regulation of adhesion in sympathetic neurons. The cleavage of RET generatesan N-terminal truncated fragment that functions as a cadherin accessory protein, modifying cadherin environment and potentiating cadherin-mediated cell aggregation. Thus, the caspase cleav age of RET generates two RET fragments: one intracellular domain that can trigger cell death in apoptotic permissive settings, and one membrane-anchored ectodomain with cadherin accessory activity. We propose that this latter function may notably be important for the adequate development of the superior cervical ganglion. © 2011 by The American Society for Biochemistry and Molecular Biology, Inc.