%0 Journal Article
%T RGD-Dependent Epithelial Cell-Matrix Interactions in the Human Intestinal Crypt
%A Yannick D. Benoit
%A Jean-Fran£¿ois Groulx
%A David Gagn¨¦
%A Jean-Fran£¿ois Beaulieu
%J Journal of Signal Transduction
%D 2012
%I Hindawi Publishing Corporation
%R 10.1155/2012/248759
%X Interactions between the extracellular matrix (ECM) and integrin receptors trigger structural and functional bonds between the cell microenvironment and the cytoskeleton. Such connections are essential for adhesion structure integrity and are key players in regulating transduction of specific intracellular signals, which in turn regulate the organization of the cell microenvironment and, consequently, cell function. The RGD peptide-dependent integrins represent a key subgroup of ECM receptors involved in the maintenance of epithelial homeostasis. Here we review recent findings on RGD-dependent ECM-integrin interactions and their roles in human intestinal epithelial crypt cells. 1. Introduction Cell contacts with the extracellular matrix (ECM) provide both cohesive and functional properties in a variety of tissues, such as epithelia, nerves, muscle, and stroma, through specific interactions with cell membrane receptors [1, 2]. All ECMs are made up of collagen fibrils and/or networks, proteoglycans as well as specialized glycoproteins such as fibronectin and laminins that are archetypal of interstitial ECM and basement membrane (BM), respectively [3, 4]. Cells from multiple origins interact with ECM molecules using a variety of receptors, most of them being members of the integrin superfamily [2]. Integrins are noncovalent transmembrane ¦Á/¦Â heterodimers. In mammals, over 24 distinct integrin heterodimers have been characterized to date, describing the association between 18¦Á and 8¦Â subunits [5¨C7]. The fact that integrin-mediated connections between the ECM and the cytoplasm regulate key cell functions such as adhesion, migration, proliferation, apoptosis, and differentiation is well recognized [8¨C11]. Epithelia express a wide variety of typical integrin receptors such as the ¦Á1¦Â1, ¦Á2¦Â1, ¦Á3¦Â1, and ¦Á6¦Â4 integrins that serve as collagen and/or laminin receptors [12¨C15]. Although less well documented in epithelia, the RGD-dependent integrins are another group of receptors that appears to be involved in epithelial cell homeostasis [15¨C17]. RGD-dependent integrins include ¦Á5¦Â1-, ¦Á8¦Â1-, and ¦ÁV-containing integrins and are named as such because they specifically recognize the RGD motif, a sequence of three amino acids (Arg-Gly-Asp) found in many ECM molecules such as fibronectin and osteopontin [5, 12, 14, 15]. Collectively, these interactions are termed the ¡°RGD-dependent adhesion system¡± (Figure 1). Interestingly, RGD-dependent cell interactions represent a key role in hierarchical assembly and maturation of adhesion structures including focal complexes (FXs),
%U http://www.hindawi.com/journals/jst/2012/248759/