Effects of Structure of Rho GTPase-activating Protein DLC-1 on Cell Morphology and Migration

• Published in: The Journal of biological chemistry 2008-11, Vol.283 (47), p.32762-32770
• Main Authors: Kim, Tai Young, Healy, Kevin D., Der, Channing J., Sciaky, Noah, Bang, Yung-Jue, Juliano, Rudy L.
• Format: Article
• Language: English
• Subjects: Actins - chemistry; Amino Acid Motifs; Cell Line; Cell Movement; Cell Shape; Focal Adhesions; Genes, Dominant; GTPase-Activating Proteins - metabolism; Humans; Models, Biological; Mutation; Protein Structure, Tertiary; rho GTP-Binding Proteins - metabolism; Structure-Activity Relationship; Tumor Suppressor Proteins - chemistry; Tumor Suppressor Proteins - physiology
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1074/jbc.M800617200

DLC-1 encodes a Rho GTPase-activating protein (RhoGAP) and negative regulator of specific Rho family proteins (RhoA-C and Cdc42). DLC-1 is a multi-domain protein, with the RhoGAP catalytic domain flanked by an amino-terminal sterile α motif (SAM) and a carboxyl-terminal START domain. The roles of these domains in the regulation of DLC-1 function remain to be determined. We undertook a structure-function analysis involving truncation and missense mutants of DLC-1. We determined that the amino-terminal SAM domain functions as an autoinhibitory domain of intrinsic RhoGAP activity. Additionally, we determined that the SAM and START domains are dispensable for DLC-1 association with focal adhesions. We then characterized several mutants for their ability to regulate cell migration and identified constitutively activated and dominant negative mutants of DLC-1. We report that DLC-1 activation profoundly alters cell morphology, enhances protrusive activity, and can increase the velocity but reduce directionality of cell migration. Conversely, the expression of the amino-terminal domain of DLC-1 acts as a dominant negative and profoundly inhibits cell migration by displacing endogenous DLC-1 from focal adhesions.