Basic fibroblast growth factor from human keratinocytes is a natural mitogen for melanocytes.

TLDR

Human melanocytes require basic fibroblast growth factor and cAMP to survive and proliferate in pure culture; without these factors they die even in the presence of serum. The study aims to identify the melanocyte growth factor produced by keratinocytes as basic fibroblast growth factor. This was demonstrated by neutralizing antibodies to bFGF and a synthetic peptide that blocks its receptor binding, which abolished the mitogenic activity. Keratinocyte‑derived bFGF, which is cell‑associated, increases after UVB irradiation and is present in keratinocyte transcripts but not melanocytes, sustains melanocyte survival for weeks without added bFGF or cAMP, demonstrating that it is the natural mitogen for normal human melanocytes in vivo.

Abstract

To survive and proliferate in pure culture, human melanocytes require basic fibroblast growth factor (bFGF) and cAMP. Without these factors, even in the presence of serum, the cells die. Melanocytes cultured in the presence of keratinocytes, however, survive for weeks without added bFGF and cAMP. We show here that the growth factor for melanocytes produced by human keratinocytes is bFGF because its activity can be abolished by neutralizing antibodies to bFGF and by a bFGF synthetic peptide that inhibits the binding of the growth factor to its receptor. The melanocyte mitogen in keratinocytes is cell associated and increases after irradiation with ultraviolet B. Northern blots reveal bFGF gene transcripts in keratinocytes but not melanocytes. These studies demonstrate that bFGF elaborated by keratinocytes in vitro sustains melanocyte growth and survival, and they suggest that keratinocyte-derived bFGF is the natural growth factor for normal human melanocytes in vivo.