Characterization of L-plastin interaction with beta integrin and its regulation by micro-calpain.
Recent evidences suggest that plastin/fimbrin is more than a simple actin cross-linking molecule. In this context and based on the fact that other members of the same family interact with transmembrane proteins, such as integrins, we have investigated a possible interaction between L-plastin and integrins. By combining coimmunoprecipitation of endogenous proteins and in vitro techniques based on solid phase and solution assays, we demonstrate that L-plastin is an additional binding partner for the beta-chain of integrin and confirmed that both proteins display some colocalization. We then show that L-plastin binds to the cytoplasmic domain of beta1 integrin and to beta1 and beta2 peptides. Using recombinant L-plastin domains, we demonstrate that the integrin-binding sites are not located in NH(2) terminal part of L-plastin but rather in the two actin-binding domains. Using pull-down, cross-linking experiments, and enzyme-linked immunosorbent assay, we show that the L-plastin/integrin complex is regulated by mu-calpain cleavage and is not directly dissociated by calcium. Indeed, despite the ability of calpain to cleave both proteins, only the cleavage of beta integrin hindered the formation of the L-plastin/integrin complex. We discuss these results in the light of the three-dimensional structure of the actin-binding domains of L-plastin.
Le Goff
E
E
UMR CNRS 5554, Institut des Sciences de l'Evolution, Université Montpellier 2, Place Eugène Bataillon, 34095 Montpellier, Cedex 05, France.
Vallentin
A
A
Harmand
P-O
PO
Aldrian-Herrada
G
G
Rebière
B
B
Roy
C
C
Benyamin
Y
Y
Lebart
M-C
MC
D002154:Calpain / Q000378:metabolism*; D045744:Cell Line, Tumor; D006801:Humans; D039641:Integrin beta Chains / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000378:metabolism*; D008840:Microfilament Proteins / Q000378:metabolism*; D018613:Microscopy, Confocal; D011485:Protein Binding
D039641:Integrin beta Chains; D008562:Membrane Glycoproteins; D008840:Microfilament Proteins; C026742:plastin; D002154:Calpain