FERM Domain Interaction Promotes FAK Signaling

Abstract

From the results of deletion analyses, the FERM domain of FAK has been proposed to inhibit enzymatic activity and repress FAK signaling. We have identified a sequence in the FERM domain that is important for FAK signaling in vivo. Point mutations in this sequence had little effect upon catalytic activity in vitro. However, the mutant exhibits reduced tyrosine phosphorylation and dramatically reduced Src family kinase binding. Further, the abilities of the mutant to transduce biochemical signals and to promote cell migration were severely impaired. The results implicate a FERM domain interaction in cell adhesion-dependent activation of FAK and downstream signaling. We also show that the purified FERM domain of FAK interacts with full-length FAK in vitro, and mutation of this sequence disrupts the interaction. These findings are discussed in the context of models of FAK regulation by its FERM domain.

We thank Joan Taylor, Shelley Earp, Lee Graves, Vidhya Iyer, and Pat Lyons for helpful comments on the manuscript. Thanks also go to Brenda Temple for help with homology modeling and to Vita Golubovskaya for providing purified FAK. Thanks go to Alison Worsham for exceptional technical assistance and to Keith Burridge for the use of his microscope. Special thanks go to Danielle Scheswohl and Martin Playford for their assistance during revision of the manuscript. We also thank Eric Schaefer for helpful discussions during the course of this study.

This project is supported by NIH grant CA90901 (to M.D.S.). V.G.-N. is supported by a predoctoral assistantship from the Department of Defense (DAMD 17-00-1-0377).