Cultured human keratinocytes synthesize and secrete endothelin-1.
The human epidermal-melanin unit exists as a complex interplay of cell-cell interactions. Melanocytes synthesize melanin and transfer it to the surrounding keratinocytes, which, in turn, produce factors that affect melanocyte homeostasis, growth, and melanization. Endothelin-1 (ET-1), a vasoconstrictor peptide produced by endothelial cells, has recently been shown to stimulate human melanocyte proliferation and tyrosinase activity. To investigate the possibility that keratinocytes synthesize and secrete ET-1, we grew human keratinocytes in a defined serum-free medium and measured ET-1 levels in the keratinocytes and the keratinocyte-conditioned medium. Northern analysis of keratinocyte total RNA also was performed. We found that human keratinocytes express preproET-1 mRNA and translate the message to ET-1 protein, which is secreted into the keratinocyte medium. Human keratinocytes produced ET-1 in a time-dependent manner with total production of 20.1 +/- 1.1 pg ET-1/10(6) cells at 24 h (n = 7). Although total ET-1 production (secreted plus cell-associated ET-1) was similar, the proportion of secreted versus cell-associated ET-1 varied widely among the different donors. We have found that human keratinocytes synthesize and secrete ET-1 in vitro. From these data we believe that the keratinocyte could be an in vivo epidermal source of this melanocyte growth and pigmentation factor.
Yohn
J J
JJ
Department of Dermatology, University of Colorado School of Medicine, Denver.
Morelli
J G
JG
Walchak
S J
SJ
Rundell
K B
KB
Norris
D A
DA
Zamora
M R
MR
D015152:Blotting, Northern; D002478:Cells, Cultured; D019332:Endothelin-1; D016232:Endothelins / Q000096:biosynthesis* / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D015603:Keratinocytes / Q000378:metabolism*; D011498:Protein Precursors / Q000235:genetics; D012333:RNA, Messenger / Q000378:metabolism; D013997:Time Factors
D019332:Endothelin-1; D016232:Endothelins; D011498:Protein Precursors; D012333:RNA, Messenger