INVESTIGATION OF THE INFLUENCE OF EXTRACELLULAR-MATRIX PROTEINS ON NORMAL HUMAN MELANOCYTE MORPHOLOGY AND MELANOGENIC ACTIVITY

Several studies have indicated that extracellular matrix (ECM) protein s can influence melanocyte behaviour in vitro. However, the choice of medium is known to have a profound effect on melanocyte behaviour and it is currently difficult to ascribe which reported effects are due to ECM proteins and those which are attributable to the medium used in t hese different studies, The purpose of this study was to learn more ab out the influence of ECM proteins on melanocyte function by examining a range of cell-derived and individual ECM proteins for their impact o n melanocyte tyrosinase activity in cells cultured under conditions of varying mitogenic drive. We found that ECM derived from human dermal fibroblasts, bovine endothelial cells and a human endothelial cell lin e as well as collagen I, collagen IV, fibronectin, and to a lesser ext ent laminin, were all capable of increasing tyrosinase activity in cul tures of normal melanocytes. Effects of these ECM were seen most consi stently in media with relatively few mitogens, for example ECM protein s influenced melanocyte morphology and this was seen most readily in c ells cultured in medium without any mitogens (which ordinarily fails t o support melanocyte survival). This study illustrates that ECM protei ns can influence melanocyte morphology, proliferation, and tyrosinase activity in vitro and supports a possible role of ECM proteins in the regulation of melanocyte function in vivo.