Human Fibroblasts with Mutations in COL5A1 and COL3A1 Genes Do Not Organize Collagens and Fibronectin in the Extracellular Matrix, Down-regulate α2β1 Integrin, and Recruit αvβ3 Instead of α5β1 Integrin

Abstract

Dermal fibroblasts derived from types I and IV EhlersDanlos syndrome (EDS) patients, carrying mutations in. Functionblocking antibodies to COLLV, COLLIII, or ␣ 2 ␤ 1 integrin induce in control fibroblasts an EDS-like phenotype. These results show that in human fibroblasts ␣ 2 ␤ 1 integrin organization and function are controlled by its ligand, and that the ␣ 2 ␤ 1 -COLL interaction, in turn, regulates FN integrin receptor recruitment: high ␣ 2 ␤ 1 integrin levels induce ␣ 5 ␤ 1 integrin organization, while low ␣ 2 ␤ 1 integrin levels lead to ␣ v ␤ 3 integrin organization. The extracellular matrix (ECM)1 is a complex structure formed by distinct molecular networks that interact with specific cell receptors, triggering numerous responses that play essential roles in cell behavior regulation (1). The ECM provides a substrate for cell migration during embryonic development and wound healing, regulating tissue architecture and morphogenesis (2), and is also signaling variations in the cell microenvironment affecting cell proliferation, differentiation, and death (3-7).Collagens (COLLs) and fibronectin (FN) are major ECM protein components (1, 8 -10). COLLs, the most abundant proteins of connective tissues, are formed by three polypeptide chains, synthesized as propeptide (pro-␣ chains), coiled into triple helices, and encoded by the same or different genes (11). Types I, III, V, and XI COLLs are organized in fibrillar structures and are therefore referred to as fibrillar COLLs. In particular, COLLIII is an ␣ 1 (III) 3 homotrimer encoded by the COL3A1 gene and is mainly distributed in skin, tendon, aorta, and cornea (12), whereas COLLV is a quantitatively minor fibrillar COLL with a broad tissue distribution that regulates COLLI fibrillogenesis (13). COLLV molecules may contain ␣1(V), ␣2(V) and ␣3(V) or ␣1(V) 2 ␣2(V) chains (13).Mutations in COLLs are related to a variety of hereditary connective tissue disorders one of which is Ehlers-Danlos syndrome (EDS), a group of heterogeneous diseases (at least 11 types) caused by alterations in different COLL genes, COL1A1, COL1A2, COL3A1, COL5A1,, and to mutations in lysyl hydroxylase (18) and N-proteinase genes (19), altering the post-translational modification of COLLs. In particular, mutations in COL5A1 and COL5A2 genes have been reported in EDSI patients showing classical signs of the syndrome, i.e. widespread scarring and bruising, skin hyperextensibility, and joint laxity (15-16). Mutations in COL3A1 genes have been disclosed in EDSIV patients showing as common features vascular rupture (vascular type), colonic perforation, thin, translucent skin, and severe bruising (15)(16)(17)(18)(19)(20).FN is a dimeric glycoprotein that triggers cell adhesion, migration, cell cycle progression, and differentiation (4,7,21). FN deposition in vivo represents the initial event during fibrillogenesis of connective tissue matrices occurring during embryogenesis and wound healing (3,22,23). Human skin fibroblasts adhere in vitro through the organization of an ECM mainly composed of FN an...

Fibronectin-dependent collagen I deposition modulates the cell response to fibronectin

“…This defect could be rescued by addition of type I collagen or the CB.7 fragment of collagen containing the fibronectin binding site (23). Cells containing mutations of other collagen genes (␣1 type V or ␣1 type III) are also defective in organizing collagen and fibronectin in the ECM; the defect in fibronectin fibril formation in cells with mutant type V or III collagen is likely due to downregulation of ␣ 5 ␤ 1 -integrin (96). Mutations in type II collagen result in abnormal deposition of both type II collagen and fibronectin.…”

Diminished Type III Collagen Promotes Myofibroblast Differentiation and Increases Scar Deposition in Cutaneous Wound Healing

“…Previous mechanisms by which ECM has been shown to alter cell activity and fate include their ability to modulate integrin expression, regulate growth factor expression and bioavailability, and control matrix metalloproteinase production and activation. Although the detailed mechanism by which Col3 modulates myofibroblast differentiation is currently under investigation, data by Zoppi et al [2004] suggest that Col3 regulation of integrin expression may play a role in this process. Fibroblasts isolated from individuals with vascular EDS express increased ␣ v and decreased ␣ 5 ␤ 1 and ␣ 2 ␤ 1 inte grins compared to those isolated from individuals unaffected by EDS.…”

Extracellular Matrix and Dermal Fibroblast Function in the Healing Wound

“…[63][64][65][66] Likewise, collagen type V has been shown to regulate collagen I fiber assembly, with mice deficient in collagen V demonstrating large structurally abnormal collagen fibrils. 67,68 However its presence has been associated with decreased dermal fibroblast apoptosis, increased Earliest demonstrable histologic appearance and regular histologic appearance of ECM components in human wounds is indicated.…”