Abrogating effect of a xanthophyll carotenoid astaxanthin on the stem cell factor-induced stimulation of human epidermal pigmentation.
We established a model for the stem cell factor (SCF)-associated stimulation of human epidermal equivalent (HEE) pigmentation. The addition of SCF (at 5 nM) gradually stimulated the visible pigmentation of HEEs over 14 days of treatment. A time course study using real-time RT-PCR and western blotting analysis demonstrated that the expression of all melanocyte-specific genes and proteins examined was gradually up-regulated over 7-10 days of treatment with SCF. The addition of astaxanthin (Ax) at concentrations of 1, 4, or 8 μM markedly abolished the SCF- but not the endothelin (EDN)1-elicited increase in visible pigmentation over 14 days in a dose-dependent manner, with almost complete inhibition at 8 μM. While no degeneration of the epidermal tissue was visible at day 14 by HE staining, melanin deposition throughout the epidermis was markedly reduced in the Ax-treated HEEs at day 14 compared to untreated controls. Ax significantly reduced the eumelanin content of HEEs to the non-SCF-stimulated level at concentrations of 4 or 8 μM compared with untreated controls. Real-time RT-PCR and western blotting of Ax-treated HEEs revealed that the SCF-stimulated expression of tyrosinase (TYR), TYR-related protein-1 (TYRP1), and Pmel17, as well as microphthalmia-associated transcription factor (MITF), is significantly suppressed by Ax at the transcriptional and translational levels. Studies using cultured normal human melanocytes revealed that pre-treatment with Ax interrupts the SCF- but not the EDN1-induced stimulation of TYR activity, and there was no direct inhibitory effect of Ax on TYR activity in vitro. These findings indicate that Ax attenuates SCF-stimulated pigmentation by directly interrupting SCF-associated intracellular signaling linkages through increased expression of MITF, which leads to the stimulated expression of melanogenic genes and proteins in a reactive oxygen species depletion-independent mechanism.
School of Bioscience and Biotechnology, Tokyo University of Technology, Hachioji, Japan.
Hiroaki
H
Nakajima
Katsunori
K
Fukazawa
Yuki
Y
Wakabayashi
Kazumasa
K
Wakamatsu
Kazuhiro
K
Senda
Genji
G
Imokawa
D002478:Cells, Cultured; D019332:Endothelin-1 / Q000378:metabolism; D004789:Enzyme Activation / Q000187:drug effects / Q000276:immunology; D004817:Epidermis / Q000187:drug effects*; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D017495:Hyperpigmentation / Q000378:metabolism*; D008544:Melanocytes / Q000187:drug effects / Q000378:metabolism*; D008562:Membrane Glycoproteins / Q000235:genetics / Q000378:metabolism; D051739:Microphthalmia-Associated Transcription Factor / Q000235:genetics / Q000378:metabolism; D014442:Monophenol Monooxygenase / Q000235:genetics / Q000378:metabolism; D010088:Oxidoreductases / Q000235:genetics / Q000378:metabolism; D012880:Skin Pigmentation / Q000187:drug effects*; D019089:Stem Cell Factor / Q000037:antagonists & inhibitors* / Q000494:pharmacology; D024341:Xanthophylls / Q000494:pharmacology; D058951:gp100 Melanoma Antigen / Q000378:metabolism
D019332:Endothelin-1; D008562:Membrane Glycoproteins; D051739:Microphthalmia-Associated Transcription Factor; D019089:Stem Cell Factor; D024341:Xanthophylls; D058951:gp100 Melanoma Antigen; C005948:astaxanthine; D010088:Oxidoreductases; C489799:TYRP1 protein, human; D014442:Monophenol Monooxygenase