CIZ, a Zinc Finger Protein That Interacts with p130^cas and Activates the Expression of Matrix Metalloproteinases

Abstract

p130^cas (Cas) is a docking protein that contains an SH3 domain and multiple tyrosine residues. p130^cas is located at focal adhesions, is tyrosine phosphorylated in response to integrin stimulation, and is thought to transmit signals, via c-Crk and other proteins, for the remodeling of actin stress fibers and cell movement. In a search for the ligands of the SH3 domain of p130^cas by far-Western screening, we cloned a novel protein named CIZ (for Cas-interacting zinc finger protein). CIZ consists of the following: a putative leucine zipper; a serine/threonine-rich region; a proline-rich sequence; five, six, or eight Krüppel-type C₂H₂ zinc fingers; and the glutamine-alanine repeat. CIZ binds Cas in cells and is located in the nucleus and at focal adhesions. We showed that CIZ is a nucleocytoplasmic shuttling protein, by using the transient interspecies heterokaryon formation assay. In order to search for the targets of CIZ in nucleus, we determined the DNA binding consensus of CIZ as (G/C)AAAAA(A) by cyclic amplification and selection of targets analysis. The consensus-like sequences are found in several promoters of matrix metalloproteinases (MMPs), which are the enzymes used to degrade the extracellular matrix proteins. CIZ binds to a consensus-like sequence in the MMP-1 (collagenase) promoter. Overexpression of CIZ upregulates the transcriptions from MMP-1, MMP-3 (stromelysin), and MMP-7 (matrilysin) promoters, and this transactivation was enhanced in the presence of Cas. Furthermore, the stable overexpression of CIZ promoted the production of MMP-7 in culture medium. In summary, CIZ, a novel zinc finger protein, binds Cas, is a nucleocytoplasmic shuttling protein, and regulates the expression of MMPs.

ACKNOWLEDGMENTS

We thank M. Yoshida (University of Tokyo), T. Takenawa (University of Tokyo), T. Yamamoto (University of Tokyo), and B. J. Mayer (Harvard Medical School) for generously providing the leptomycin B, GST-Ash/Grb2 SH3, GST-Fyn SH3, and GST-Abl SH3, respectively. We appreciate P. Angel (German Cancer Research Center) and H. Rahmsdorf (Kernforschungszentrum Karlsruhe) for kindly providing the human MMP-1 promoter-encoding plasmid. We also appreciate L. Matrisian (Vanderbilt University) for providing the human MMP-7 promoter and the rat MMP-3 promoter. We thank K. Chida (University of Tokyo) for helpful advice.

This work was supported in part by Fellowships in Cancer Research of the Japan Society for the Promotion of Science for Young Scientists.