Fibronectin fragments modulate human retinal capillary cell proliferation and migration

Abstract

Capillary morphogenesis involves cell-cell and cellmatrix interactions. Proteases elaborated by capillary cells modify the extracellular matrix (ECM) to facilitate capillary tube formation. Previously, we detected the presence of fibronectin fragments (Fn-f) associated with the proform of matrix metalloprotease-2 (MMP-2) in conditioned medium of human retinal endothelial cells (HRECs). Association of this fragment to latent MMP-2 prevented autocatalytic activation of MMP-2, suggesting a modulatory role of Fn-f in MMP-2 activation. In this report, we examined the potential role of Fn-f on two processes involved in angiogenesis, proliferation and migration of vascular cells. The effects of Fn-f on proliferation were determined by DNA synthesis and cell counts. Their effects on migration were assessed using modified Boyden chambers. Seven Fn-f were tested on vascular cell migration and/or proliferation. Three Fn-f induced migration. Fn-f of 30-kDa and 120-kDa size positively affected proliferation of microvascular cells but not macrovascular cells. A 45-kDa gelatin binding fragment of Fn inhibited HRECproliferation but stimulated pericyte and smooth muscle cell proliferation. The potency of these fragments exceeded that of the known angiogenic growth factor, basic fibroblast growth factor (bFGF), on HREC migration. ECM components such as fibronectin may influence capillary morphogenesis by the generation of fragments that can modulate proliferation, migration, and protease activation. In the setting of diabetes, excess Fn is generated and is available for degradation. Thus, the production of Fn-f may be specifically relevant to the angiogenesis observed in proliferative diabetic retinopathy.

Ultraviolet light-irradiated collagen III modulates expression of cytoskeletal and surface adhesion molecules in rat aortic smooth muscle cells in vitro

“…Large polymeric and mature molecules usually promote adhesion, quiescence and differentiation of VSMCs, whereas their physical and chemical modifications, e.g. fragmentation and glycation, or their immature mono-or oligomeric forms allow migration and proliferation of these cells [14,15,17,33]. Our finding of less developed fibrillar, or even granular forms of α-actin, an important marker of VSMC differentiation [3,11,14], in VSMCs on UV-modified collagen is in accordance with this concept and suggests a higher tendency of these cells to so-called "phenotypic modulation", i.e.…”

Fibronectin Fragmentation Is a Feature of Periodontal Disease Sites and Diabetic Foot and Leg Wounds and Modifies Cell Behavior

“…MMP‐1 production was induced by a recombinant extra domain‐A FN fragment in rabbit cartilage explant cultures and chondrocytes, 52 likely through expression of proinflammatory cytokines interleukin (IL)‐1α and −1β. A 90‐kDa FN fragment was expressed by human retinal endothelial cells of diabetic and non‐diabetic origin after exposure to glucose 53 . This FN fragment was strongly attached to MMP‐2 and inhibited MMP‐2 autoactivation.…”

Targeting Invasion Induction as a Therapeutic Strategy for the Treatment of Cancer

“…The cell-binding domain also induces monocytes to extravasate from proximal vessels, enabling them to enter the wound and differentiate into inflammatory macrophages, which have important regulatory functions in wound healing [116]. The cell-binding domain also stimulates normal human endothelial cell motility in vitro [23]. Thus, the invasive/migratory phenotype expressed by epithelial cells and fibroblasts after wounding may result from fibronectin fragmentation and α5β1 integrin-mediated signaling.…”

“…Hence, uPA has been suggested to play an important role in VEGF-stimulated cell migration [139]. Since uPA degrades pFn [14,15], producing fragments that interact with α5β1 integrin to induce angiogenesis [22,23], the induction of uPA and uPAR expression by VEGF may play an in important role in VEGF-mediated endothelial cell sprouting and invasion of the extracellular matrix. This effect could be enhanced by the association of secreted VEGFR-1 with α5β1 integrin [135].…”

“…Digestion of the plasma and cellular forms of fibronectin produces fragments that diffuse from the wound [14,15], and are bound by the α5β1 integrin fibronectin receptors of leukocytes and fibroblasts to induce invasion and formation of the wound provisional matrix [19][20][21]. The interaction of α5β1 with fibronectin fragments also induces invasion of the provisional matrix by endothelial cells to initiate neovascularization [22,23], as well as migration over the provisional matrix by epithelial cells during re-epithelialization [24,25]. Moreover in the absence of α 4 β 1 binding, the interaction of α 5 β 1 with the fibronectin cell binding domain has also been shown to induce MMP-1 expression in cultured fibroblasts [26].…”