Characterization of the Ca2+ -regulated ezrin-S100P interaction and its role in tumor cell migration.
Ezrin is a multidomain protein providing regulated membrane-cytoskeleton contacts that play a role in cell differentiation, adhesion, and migration. Within the cytosol of resting cells ezrin resides in an autoinhibited conformation in which the N- and C-terminal ezrin/radixin/moesin (ERM) association domains (ERMADs) interact with one another. Activation of the ezrin membrane-cytoskeleton linker function requires an opening of this interdomain association that can result from phosphatidylinositol 4,5-bisphosphate binding to the N-ERMAD and threonine 567 phosphorylation in the C-ERMAD. We have shown that ezrin can also be activated by Ca(2+)-dependent binding of the EF-hand protein S100P. We now provide a quantitative analysis of this interaction and map the respective binding sites to the F2 lobe in the ezrin N-ERMAD and a stretch of hydrophobic residues in the C-terminal extension of S100P. Phospholipid binding assays reveal that S100P and phosphatidylinositol 4,5-bisphosphate compete to some extent for at least partially overlapping binding sites in N-ERMAD. Using interaction-competent as well as interaction-incompetent S100P derivatives and permanently active ezrin mutants, we also show that the protein interaction and a resulting activation of ezrin promote the transendothelial migration of tumor cells. Thus, a prometastatic role of ezrin and S100P that had been proposed based on their overexpression in highly metastatic cancers is probably due to a direct interaction between the two proteins and the S100P-mediated activation of ezrin.
Austermann
Judith
J
Institute of Medical Biochemistry, Center for Molecular Biology of Inflammation, University of Muenster, 48149 Muenster, Germany.
Nazmi
Ali Reza
AR
Müller-Tidow
Carsten
C
Gerke
Volker
V
D002118:Calcium / Q000737:chemistry*; D002135:Calcium-Binding Proteins / Q000737:chemistry*; D002465:Cell Movement; D003598:Cytoskeletal Proteins / Q000737:chemistry*; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008833:Microcirculation; D008954:Models, Biological; D009362:Neoplasm Metastasis; D009363:Neoplasm Proteins / Q000737:chemistry*; D009369:Neoplasms / Q000378:metabolism*; D010743:Phospholipids / Q000737:chemistry; D011485:Protein Binding; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry; D020349:Surface Plasmon Resonance; D000099149:Ezrin
D002118:Calcium; D002135:Calcium-Binding Proteins; D003598:Cytoskeletal Proteins; D009363:Neoplasm Proteins; D010743:Phospholipids; D011994:Recombinant Proteins; D000099149:Ezrin; C103003:S100P protein, human