title: Novel role for the Lu/BCAM-spectrin interaction in actin cytoskeleton reorganization.
abstract: Lu/BCAM (Lutheran/basal cell-adhesion molecule) is a laminin 511/521 receptor expressed in erythroid and endothelial cells, and in epithelial tissues. The RK573-574 (Arg573-Lys574) motif of the Lu/BCAM cytoplasmic domain interacts with αI-spectrin, the main component of the membrane skeleton in red blood cells. In the present paper we report that Lu/BCAM binds to the non-erythroid αII-spectrin via the RK573-574 motif. Alanine substitution of this motif abolished the Lu/BCAM-spectrin interaction, enhanced the half-life of Lu/BCAM at the MDCK (Madin-Darby canine kidney) cell surface, and increased Lu/BCAM-mediated cell adhesion and spreading on laminin 511/521. We have shown that the Lu/BCAM-spectrin interaction mediated actin reorganization during cell adhesion and spreading on laminin 511/521. This interaction was involved in a laminin 511/521-to-actin signalling pathway leading to stress fibre formation. This skeletal rearrangement was associated with an activation of the small GTP-binding protein RhoA, which depended on the integrity of the Lu/BCAM laminin 511/521-binding site. It also required a Lu/BCAM-αII-spectrin interaction, since its disruption decreased stress fibre formation and RhoA activation. We conclude that the Lu/BCAM-spectrin interaction is required for stress fibre formation during cell spreading on laminin 511/521, and that spectrin acts as a signal relay between laminin 511/521 and actin that is involved in actin dynamics.
authors: Inserm, UMR-S 665, Paris, F-00-75015, France.
authors: Emmanuel
authors: E
authors: Collec
authors: Marie-Christine
authors: MC
authors: Lecomte
authors: Wassim
authors: W
authors: El Nemer
authors: Yves
authors: Y
authors: Colin
authors: Caroline
authors: C
authors: Le Van Kim
mesh_terms: D000199:Actins / Q000378:metabolism*; D020816:Amino Acid Motifs; D000818:Animals; D002448:Cell Adhesion / Q000502:physiology; D015815:Cell Adhesion Molecules / Q000378:metabolism*; D002460:Cell Line; D003599:Cytoskeleton / Q000378:metabolism; D004285:Dogs; D004912:Erythrocytes / Q000378:metabolism; D006801:Humans; D008188:Lutheran Blood-Group System / Q000378:metabolism*; D017474:Receptors, Laminin / Q000378:metabolism; D013049:Spectrin / Q000378:metabolism*
chemical_list: D000199:Actins; C090228:BCAM protein, human; D015815:Cell Adhesion Molecules; D008188:Lutheran Blood-Group System; D017474:Receptors, Laminin; D013049:Spectrin