Fibronectin matrix deposition and fibronectin receptor expression in healing and normal skin.
During cutaneous tissue organization, numerous critical interactions occur between cells and the extracellular matrix (ECM). Cell-matrix interactions depend on the presence of ECM receptors. Many ECM receptors, known as integrins, are heterodimeric glycoproteins consisting of one alpha and one beta chain. Integrins containing beta 1 or beta 3 chains are ECM receptors, whereas those containing beta 2 chains are leukocyte cell-cell receptors. We have used porcine cutaneous wounds as a paradigm for tissue organization and probed healing wounds and adjacent normal skin with polyclonal antibodies to fibronectin and fibronectin (alpha 5 beta 1) receptor. During re-epithelialization, the epidermis transits over a provisional matrix containing fibronectin. Migrating epidermal cells expressed fibronectin receptors in a bright linear peripheral pattern. At 10 days, when reepithelialization was complete and the basement membrane was re-established, the fibronectin matrix was markedly reduced and fibronectin-receptor expression was limited to the basolateral aspect of basal cells, as observed in normal epidermis. Beneath the migrating epidermis in 5-d wounds, granulation tissue had filled 80% of the wound space. Day-5 wound fibroblasts did not express fibronectin nor other beta 1 integrin receptors, were randomly oriented, and contained no actin bundles. Fibronectin fibrils were assembled on the surfaces of day-5 wound fibroblasts but formed few linkages between cells. Day-7 wound fibroblasts expressed fibronectin receptors, contained peripheral cytoplasmic actin bundles consistent with a contractile fibroblast phenotype, and were coaligned across the wound in parallel array with interconnecting fibronectin fibrils. The wounds contracted between 7 and 10 days. Thus the migrating epidermis consistently expressed fibronectin receptors. Fibronectin receptors were expressed by fibroblasts just prior to wound contraction.
Clark
R A
RA
Department of Dermatology and Medicine, University of Colorado School of Medicine, Denver.
D000818:Animals; D005109:Extracellular Matrix / Q000378:metabolism*; D005353:Fibronectins / Q000378:metabolism*; D006801:Humans; D016023:Integrins / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism; D017469:Receptors, Fibronectin; D011971:Receptors, Immunologic / Q000378:metabolism*; D012867:Skin / Q000293:injuries / Q000378:metabolism*; D014945:Wound Healing / Q000502:physiology*
D005353:Fibronectins; D016023:Integrins; D011956:Receptors, Cell Surface; D017469:Receptors, Fibronectin; D011971:Receptors, Immunologic