Induction of Endothelial Cell Activation by a Triple Helical α2β1 Integrin Ligand, Derived from Type I Collagen α1(I)496–507

Abstract

Endothelial cell activation involves the elevated expression of cell adhesion molecules, chemoattractants, chemokines, and cytokines. These expression profiles may be regulated by integrin-mediated cell signaling pathways. In the current study, an ␣ 2 ␤ 1 integrin triple helical peptide ligand derived from type I collagen residues ␣1(I)496 -507 was examined for induction of human aortic endothelial cell (HAEC) activation. In addition, a "miniextracellular matrix" composed of a mixture of the ␣1(I)496 -507 ligand and a second, ␣-helical ligand incorporating the endothelial cell proliferating region of SPARC (secreted protein acidic and rich in cysteine) was studied for induction of HAEC activation. Following HAEC adhesion to ␣1(I)496 -507, mRNA expression of Eselectin-1, vascular and intercellular cell adhesion molecules-1, and monocytic chemoattractant protein-1 was stimulated, whereas that of endothelin-1 was inhibited. Enzyme-linked immunosorbent assay analysis demonstrated that E-selectin-1 and monocytic chemoattractant protein-1 expression was also stimulated, whereas endothelin-1 protein expression diminished. Engagement of the ␣ 2 ␤ 1 integrin initiated a HAEC response similar to that of tumor necrosis factor-␣-induced HAECs but was not sufficient to induce an inflammatory response. Addition of the SPARC 119 -122 region had only a slight effect on HAEC activation. Other cell-extracellular matrix interactions appear to be required to elicit an inflammatory response. The ␣ 2 ␤ 1 integrin specific triple helical peptide ligand described herein represents a more general in vitro model system by which gene expression and protein production profiles induced by binding to a single cellular receptor type can be quantified.Blood vessels are lined with a contiguous endothelial cell layer. The endothelium lies just inside the medial cell layer of vascular smooth muscle cells, which, in turn, is surrounded by a layer of connective tissue. The location of the endothelial cell lining is such that it provides the interface between the flowing blood and the medial layer of the vessel.The endothelium, under normal physiological conditions, does not bind elements in the flowing blood but instead associates with smooth muscle cells and the extracellular matrix (ECM).1 These normal cell-cell and cell-matrix interactions are maintained, in part, by integrins on the endothelial cell surface (for review, see Ref. 1). Many integrins are involved in cellmatrix interactions; for example, five integrins

Collagen Phagocytosis by Fibroblasts Is Regulated by Decorin

“…Furthermore, as the ␣2␤1 integrin is required for collagen phagocytosis by human gingival fibroblasts (6,23,24,26), a likely site for DCNinduced masking of fibrillar collagen binding is the ␣2␤1 integrin-binding site within collagen (39). Accordingly, we used DCN peptides (see below) that bind optimally to collagen, and we examined their interaction with triple helical collagen peptides mimicking the ␣2␤1 integrin-binding site of collagen (40) and a second DCN-binding sequence within collagen (41,42). Based on binding of the LRR 3 DCN peptide (but not the scrambled sequence peptide) to both of these triple helical collagen peptides, short collagen-binding sequences within DCN may mask the ␣2␤1 integrin-binding site on collagen, which is required for the phagocytosis of collagen fibrils.…”

Differential Modulation of Human Melanoma Cell Metalloproteinase Expression by α2β1 Integrin and CD44 Triple-helical Ligands Derived from Type IV Collagen

“…This presumably leads to a multitude of signaling and regulatory pathways. One of the distinct advantages of the peptide amphiphile approach is that, initially, one receptor at a time can be studied, and then a "mini-ECM" can be assembled to examine the cumulative effects of multi-receptor binding (58,59). This will allow for the examination of cooperativity between the ␣ 2 ␤ 1 integrin and CD44/CSPG.…”

Thrombin-Induced Force Development in Vascular Endothelial Cells: Contribution to Alteration of Permeability Mediated by Calcium-Dependent and -Independent Pathways

“…In the internal surface of the plasma membrane, FAU connect cytoskeleton and ASF. On the other side, FAU in extracellular surface associates with an extracellular matrix mediated by collagen (31,32). Therefore, we hypothesize that thrombin-induced EC fiber contraction involves ASF and cytoskeletal interaction.…”