Integrin receptors of human melanocytes in vivo and of melanocytes isolated and cultured from in vitro reconstituted normal human epidermis were investigated. Melanocytes were studied by high-resolution immunocytochemistry of in situ epidermis and were found to expose only the integrin subunits α3, α6, αvand β1 on their plasma membrane surface. Instead, cultured normal melanocytes expressed α3β1, α5β1, α6β1 and αvβ3, which were immunoprecipitated from both metabolically and surface-labeled cells. Betal integrins were diffused on the adhesion surface, while αvβ3 was clustered in focal contacts both in control cells and upon dendrite induction with phorbol 12-myristate 13-acetate (PMA). The functional roles of integrins were studied in vitro by cell adhesion, spreading and migration assays. The sum of the data indicated that, in normal human melanocytes: (i) adhesion to defined substrata is mainly mediated by specific β1 integrins; (ii) spreading is mainly modulated by αvβ3; (iii) the β1 and β3 heterodimers cooperate in regulating migration. The in vitro expression of two integrins (αvβ3 and α5β1) that are not exposed in situ, and their role in the spreading and migratory properties of melanocytes, strongly suggest that they are involved in regenerating a normally pigmented epidermis during wound healing by controlling melanocyte spreading and migration over a provisional matrix. Tumor promoters, such as PMA, selectively increased the expression of α3β1. We suggest that this integrin might be involved in melanocyte migration on the newly formed basement membrane during wound healing as well as in intercellular recognition of adjacent keratinocytes.
|Number of pages||12|
|Journal||Journal of Cell Science|
|Publication status||Published - May 1993|
ASJC Scopus subject areas
- Cell Biology