Molecular cloning of a murine fibronectin receptor and its expression during inflammation. Expression of VLA-5 is increased in activated peritoneal macrophages in a manner discordant from major histocompatibility complex class II.

Abstract

Macrophages secrete fibronectin (Fn)' (1-3), bind Fn (3-5), and have been reported to migrate in response to Fn fragments (6). In addition, the interaction of human macrophages with Fn provides a second signal that leads to enhanced complement and Fc receptor-mediated phagocytosis by these cells (7)(8)(9)(10)(11)(12)(13)(14) . The structure ofthe Fn receptor, or receptors, responsible for both adherence to Fn and Fn-mediated phagocytosis enhancement in macrophages is not completely understood . Previous studies have demonstrated membrane proteins on monocytes or culture-derived macrophages that interact with the 110-kD cell-binding domain of Fn (15). These proteins exhibit electrophoretic mobility typical of the recently described Fn receptor, termed VLA-5, purified from placenta, fibroblasts, the MG63 osteosarcoma cell line, erythroblasts, and platelets (reviewed in references 16-18) . This receptor is a heterodimer consisting of an ti 150-kD a chain and a 130-kD a chain under nonreducing conditions (19). Identification and sequence analysis of cDNA clones for both chains from a placental cDNA library has placed this receptor in the integrin family (18,20), whose members function in cellular adhesion . The VLA antigens form a part of this family and are defined by having a common R chain that can noncovalently combine with at least six distinct a chains (21)(22)(23)(24). We have recently demonstrated by Northern blot analysis the presence of mRNA that hybridizes with probes for both the VLA-5 a and the common VLA (3 chain in monocytes, as well as in the monocyte-like cell lines HL-60, THP, and U937 (25). In addition, partial cDNA clones that we have isolated from an HL-60 library have shown identical restriction

α5β1 Integrin Blockade Inhibits Lymphangiogenesis in Airway Inflammation

“…35 Macrophages are believed to be among the immune cells that drive lymphangiogenesis. 31,52 As macrophages express ␣5␤1 integrin in some inflammatory conditions, 53 a potential mechanism for inhibition of lymphangiogenesis by JSM8757 is prevention of macrophage recruitment. In this context, JSM6427, an ␣5␤1 integrin inhibitor similar to JSM8757, had no effect on macrophage recruitment in a model of corneal inflammation.…”

Cellular responses of embryonic hyaline cartilage to experimental wounding in vitro

“…Monoclonal antibody COL2-314m recognises an epitope in the type-I1 collagen a chain that is acccssible only when the triple helix is denatured (19). In contrast, polyclonal antibody COL2-314C recognkes exhibited this pericellular immunolabelling increased with time in culture.…”

Genetic Control of Susceptibility to Candida albicans in SM/J Mice

“…BI-1 also plays a role in actin polymerization and cell adhesion (81), mechanisms that are tightly regulated during leukocyte egress and extravasation (82). The second most significant gene product, ITGA5 (a5), is the a subunit of the fibronectin receptor (a5b1) expressed on various immune cells, mediating binding to fibronectin and extravasation toward infectious stimulus (83)(84)(85). Blockade of a5b1 resulted in attenuated zymosan-induced recruitment of neutrophils and monocytes to the peritoneum, by reducing cell adhesion and transmigration (86).…”