Expression of beta 1, beta 3, beta 4, and beta 5 integrins by human epidermal keratinocytes and non-differentiating keratinocytes.

Abstract

Abstract. We have compared the adhesive properties and integrin expression profiles of cultured human epidermal keratinocytes and a strain of nondifferentiating keratinocytes (ndk). Both cell types adhered to fibronectin, laminin, and collagen types I and IV, but ndk adhered more rapidly and at lower coating concentrations of the proteins . Antibody blocking experiments showed that adhesion of both cell types to fibronectin was mediated by the a5ß, integrin and to laminin by a 3ß1 in synergy with a2ß1 . Keratinocytes adhered to collagen with 01201, but an antibody to a2 did not inhibit adhesion of ndk to collagen . Both cell types adhered to vitronectin by a, containing integrins. Immunoprecipitation of surface-iodinated and metabolically labeled cells showed that in addition to a 2ß1, a3ß1, and a5ß1, both keratinocytes and ndk expressed a6ß4 and T HE integrins constitute a large family of cell surface molecules involved in cell-cell and cell-matrix interactions. Integrins are heterodimers, consisting of non-covalently associated a and ß subunits, both of which are transmembrane glycoproteins (Hynes, 1987) . The integrins are presently classified on the basis that one ß subunit can associate with several different a subunits : the 01 and 03 subgroups are widely expressed and are principally involved in cell-matrix interactions, whereas 0, integrins are expressed on leukocytes and are involved in cell-cell interactions (reviewed by Hemler, 1990) . However, it is now apparent that one a subunit can also associate with different ß subunits, examples being the a6ß, and a6ß4 integrins (Sonnenberg et al ., 1988a,b ;Kajiji et al., 1989) and the a,ß,, C1 .ß3, or a,ß5 integrins (Bodary and McLean, 1990;Vogel et al., 1990;Cheresh et al., 1989 ;Ramaswamy et al., 1990) . Heterodimer composition is important in determining ligand specificity (Cheresh et al., 1989; Bodary andMcLean, 1990; Sonnenberg etal ., 1990x ;Vogel et al., 1990), but there is also evidence that the same integrin can have different functions when expressed on different cell types (Elices and Hemler, 1989;Languino et al., 1989).Dr. Adams' present address

Expression of αvβ6integrin in oral leukoplakia

“…Basal keratinocytes do not normally express α v β 3 and α v β 6 integrins (Breuss et al, 1995;Haapasalmi et al, 1995). α v β 5 has been detected from the same areas of normal buccal mucosa (Adams and Watt, 1991). On the other hand, it has been also reported to be absent from normal gingival epithelium (Larjava et al, 1993).…”

Expression of Desmosomal Proteins in Rat Keratinocytes during In Vitro Differentiation.

“…Rat proliferative keratinocytes also expressed integrin β1 and the expression was down-regulated by exogenous Ca 2+ . In contrast to the induction of desmosomal proteins, human keratinocytes decrease expression of integrin β1 protein and mRNA during differentiation [1,17,33]. These results suggested that keratinocyte integrins not only mediate adhesion to extracellular matrix but also regulate the initiation of the terminal differentiation.…”

“…64(2): 123-127, 2002 The epidermis consists of multiple layers of keratinocytes. When keratinocytes of the basal layer withdraw from the cell cycle and become committed to the terminal differentiation, they detach from the basement membrane and migrate into the suprabasal layers [1,6,7,12]. During the differentiation, human keratinocytes express several proteins, transglutaminase and substrates of this enzyme such as involucrin and filaggrin, which form the cornified envelope in the keratinized layer of the epidermis.…”

“…Expression of these integrins is restricted to the basal, proliferative cell layer. In particular, integrin β1 plays a crucial role in terminal differentiation within the epidermis [1,6,7,33].It is well known that the proliferation and differentiation of cultured keratinocytes are regulated by the Ca 2+ concentration in the culture medium. Shifting cells from low Ca 2+ medium to high Ca 2+ medium results in inhibition of proliferation followed by stratification and commitment to the terminal differentiation program [9,10,23,24,28].…”

“…Expression of these integrins is restricted to the basal, proliferative cell layer. In particular, integrin β1 plays a crucial role in terminal differentiation within the epidermis [1,6,7,33].…”