Open AccessEchistatin inhibits pp125 FAK autophosphorylation, paxillin phosphorylation and pp125 FAK –paxillin interaction in fibronectin‐adherent melanoma cells
Author(s) -
Della Morte Rossella,
Squillacioti Caterina,
Garbi Corrado,
Derkinderen Pascal,
Belisario Maria A,
Girault JeanAntoine,
Di Natale Paola,
Nitsch Lucio,
Staiano Norma
Publication year - 2000
Publication title -
european journal of biochemistry
Language(s) - English
Resource type - Journals
eISSN - 1432-1033
pISSN - 0014-2956
DOI - 10.1046/j.1432-1327.2000.01561.x
Subject(s) - paxillin , focal adhesion , autophosphorylation , phosphorylation , tyrosine phosphorylation , microbiology and biotechnology , ptk2 , chemistry , fibronectin , biology , extracellular matrix , protein kinase a , mitogen activated protein kinase kinase
Echistatin, a snake‐venom RGD‐containing protein, was previously shown to disrupt cell‐matrix adhesion by a mechanism that involves the reduction of pp125 FAK tyrosine phosphorylation levels. The aim of this study was to establish the sequence of events downstream pp125 FAK dephosphorylation that could be responsible for echistatin‐induced disassembly of actin cytoskeleton and focal adhesions in fibronectin‐adherent B16‐BL6 melanoma cells. The results obtained show that echistatin induces a decrease of both autophosphorylation and kinase activity of pp125 FAK . One hour of cell exposure to echistatin caused a 39% decrease of pp125 FAK Tyr397 phosphorylation and a 31% reduction of pp125 FAK autophosphorylation activity as measured by immune‐complex kinase assay. Furthermore, 1 h of cell treatment by echistatin produced a 63% decrease of paxillin phosphorylation, as well as a reduction in the amount of paxillin bound to pp125 FAK . Immunofluorescence analysis of echistatin treated cells showed the concomitant disappearance of both paxillin and pp125 FAK from focal adhesions. The reduction of paxillin phosphorylation may represent a critical step in the pathway by which disintegrins exert their biological activity, including the inhibition of experimental metastasis in vivo .