P21-activated Kinase 1 (PAK1) Interacts with the Grb2 Adapter Protein to Couple to Growth Factor Signaling

Lorena A Puto,Kersi Pestonjamasp,Charles C King,Gary M Bokoch

doi:10.1074/jbc.m208414200

Lorena A Puto, Kersi Pestonjamasp + Show 2 more

Open Access

https://doi.org/10.1074/jbc.m208414200

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Abstract

A variety of intracellular signaling pathways are linked to cell surface receptor signaling through their recruitment by Src homology 2 (SH2)/SH3-containing adapter molecules. p21-activated kinase 1 (PAK1) is an effector of Rac/Cdc42 GTPases that has been implicated in the regulation of cytoskeletal dynamics, proliferation, and cell survival signaling. In this study, we describe the specific interaction of PAK1 with the Grb2 adapter protein both in vitro and in vivo. We identify the site of this interaction as the second proline-rich SH3 binding domain of PAK1. Stimulation of the epidermal growth factor receptor (EGFR) in HaCaT cells enhances the level of EGFR-associated PAK1 and Grb2, although the PAK1-Grb2 association is itself independent of this stimulation. A cell-permeant TAT-tagged peptide encompassing the second proline-rich SH3 binding domain of PAK1 simultaneously blocked Grb2 and activated EGFR association with PAK1, in vitro and in vivo, indicating that Grb2 mediates the interaction of PAK1 with the activated EGFR. Blockade of this interaction decreased the epidermal growth factor-induced extension of membrane lamellae. Thus Grb2 may serve as an important mechanism for linking downstream PAK signaling to various upstream pathways.

Highlights

Growth factors, cytokines, and many other hormones signal through specific cell surface receptors that contain intrinsic tyrosine kinase activity [1, 2]
We describe the specific interaction of p21-activated kinase 1 (PAK1) with the Grb2 adapter protein both in vitro and in vivo
In the work presented here, we utilized an affinity-based approach in which the PAK1 N terminus was used as a probe to isolate specific binding partners from Jurkat T cell lysates

Summary

Introduction

Cytokines, and many other hormones signal through specific cell surface receptors that contain intrinsic tyrosine kinase activity [1, 2]. A cell-permeant TAT-tagged peptide encompassing the second proline-rich SH3 binding domain of PAK1 simultaneously blocked Grb2 and activated EGFR association with PAK1, in vitro and in vivo, indicating that Grb2 mediates the interaction of PAK1 with the activated EGFR. Grb2 is a 25-kDa adapter protein that associates with activated receptor tyrosine kinases via its single SH2 domain [6].

Results

Conclusion