Decorin Regulates Endothelial Cell Motility on Collagen I through Activation of Insulin-like Growth Factor I Receptor and Modulation of α2β1 Integrin Activity

Abstract

The proteoglycan decorin is expressed by sprouting but not quiescent endothelial cells, and angiogenesis is dysregulated in its absence. Previously, we have shown that decorin core protein can bind to and activate insulin-like growth factor-I receptor (IGF-IR) in endothelial cells. In this study, we show that decorin promotes ␣2␤1 integrin-dependent endothelial cell adhesion and migration on fibrillar collagen type I. We provide evidence that decorin modulates cell-matrix interaction in this context by stimulating cytoskeletal and focal adhesion reorganization through activation of the IGF-IR and the small GTPase Rac. Further, the glycosaminoglycan moiety of decorin interacts with ␣2␤1, but not ␣1␤1 integrin, at a site distinct from the collagen I-binding A-domain, to allosterically modulate collagen I-binding activity of the integrin. We propose that induction of decorin expression in angiogenic, as opposed to quiescent, endothelial cells promotes a motile phenotype in an interstitial collagen I-rich environment by both signaling through IGF-IR and influencing ␣2␤1 integrin activity.

The integrin needle in the stromal haystack: emerging role in corneal physiology and pathology

“…On the other hand, overexpression of decorin in the keratocytes blocked TGF-β-mediated myofibroblast transformation of keratocytes (Mohan et al 2010), while decorin gene therapy inhibited corneal scarring (Mohan et al 2011). Also, decorin interacted with α2β1 in endothelial cells and modulated the collagen I binding activity of the integrin (Fiedler et al 2008). Since α2β1 is also expressed in keratocytes, it should be interesting to know whether such integrin-decorin interaction has a part in stromal wound healing.…”

Platelet adhesion to decorin but not collagen I correlates with the integrin 2 dimorphism E534K, the basis of the human platelet alloantigen (HPA)-5 system

“…5 Decorin was purified from cultured human fibroblast matrices without denaturing and/or precipitation as described. 6 The presence of decorin in a 90-150 kDa protein complex and the core protein decoron at roughly 46 kDa, and the absence of collagen I or III were established by immunoblot assay.…”

Impact of bidirectional relationships between streptococcus anginosus group and host tissue matrix components on cellular activity: role in establishment of infection

“…A migration assay was performed using endothelial cells cultured as spheroids [17]. Briefly, single uniform spheroids were prepared from 1000 EA.hy926 cells per well of a 96-well round bottom hydrophobic plate, suspended in Waymaouth MAB 87/3 medium supplemented with 5% heat-inactivated foetal calf serum and 30% methyl cellulose (Sigma Aldrich) for 48 h, 37°C, 5% CO 2 .…”

“…Briefly, single uniform spheroids were prepared from 1000 EA.hy926 cells per well of a 96-well round bottom hydrophobic plate, suspended in Waymaouth MAB 87/3 medium supplemented with 5% heat-inactivated foetal calf serum and 30% methyl cellulose (Sigma Aldrich) for 48 h, 37°C, 5% CO 2 . Spheroids were transferred, one per well of a flat bottomed 96-well hydrophilic plate, pre-coated with 0.125 mg of type 1 collagen (extracted from rat tail [17]) and cultured in 100 µl Waymouth medium supplemented with 0.5% heat-inactivated foetal calf serum, and 0 ng/ml or 100 ng/ml of SAG supernatant, 37 o C, 5% CO 2 for 0-72 h. Cells migrating away from the spheroid bodies, eventually form a ring of cells resembling sprout-like extensions associated with angiogenesis. For spheroids located close to the centre of the well, cell migration was recorded as digital images after 6 h and then every 24 h over 3 days.…”

“…Of note, targeted deletion of decorin in mice resulted in irregularly sized and shaped collagen fibril bundles, many with an over-large morphology, which was most evident in the PDL [14]. Decorin has also been proposed to influence cell signalling and proliferation of both PDL and endothelial cells either by direct binding to cell surface receptors [14][15][16][17] or by binding of growth factors in the matrix and regulating their release [11,18]. As a consequence of the constant physical forces placed on this tissue, collagens within the PDL have amongst the highest turn-over rates of all connective tissues within the body, [19] resulting in the constant renewal of the periodontal fibres, the alveolar bone proper and the anchoring Sharpey's inserts.…”