A role for tyrosinase-related protein 1 in 4-tert-butylphenol-induced toxicity in melanocytes: Implications for vitiligo.
Vitiligo presents with depigmented cutaneous lesions following localized melanocyte death. Multiple factors contribute to cell death, including genetically determined susceptibility to trauma, and environmental factors, such as exposure to 4-tert-butylphenol (4-TBP). We demonstrate that 4-TBP induces oxidative stress that is more readily overcome by melanocytes from normally pigmented individuals than from two individuals with vitiligo. The antioxidant catalase selectively and significantly reduced death of melanocytes derived from two individuals with vitiligo, indicating a role for oxidative stress in vitiligo pathogenesis. In normal melanocytes, oxidative stress results in reduced expression of microphthalmia-associated transcription factor (MITF). Melanocyte-stimulating hormone-induced expression of MITF protein caused increased sensitivity to 4-TBP, whereas sensitivity of melanomas correlated with MITF expression. MITF stimulates melanin synthesis by up-regulating expression of melanogenic enzymes such as tyrosinase-related protein-1 (Tyrp1). Although melanin content per se did not affect sensitivity to 4-TBP, expression of Tyrp1 significantly increased sensitivity. Melanocytes and melanomas that express functional Tyrp1 were significantly more sensitive to 4-TBP than Tyrp1-null cells. Thus, normal melanocytes respond to 4-TBP by reducing expression of MITF and Tyrp1. We hypothesize that melanocytes in vitiligo demonstrate reduced ability to withstand oxidative stress due, partly, to a disruption in MITF regulation of Tyrp1.
Manga
Prashiela
P
Department of Dermatology, University of Cincinnati, PO Box 670592, Cincinnati, OH 45267-0592, USA.
Sheyn
David
D
Yang
Fan
F
Sarangarajan
Rangaprasad
R
Boissy
Raymond E
RE
D016923:Cell Death / Q000187:drug effects; D002478:Cells, Cultured; D015536:Down-Regulation / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D008543:Melanins / Q000378:metabolism; D008544:Melanocytes / Q000187:drug effects*; D008545:Melanoma / Q000473:pathology; D051739:Microphthalmia-Associated Transcription Factor / Q000235:genetics; D018384:Oxidative Stress / Q000187:drug effects; D010088:Oxidoreductases / Q000378:metabolism*; D010636:Phenols / Q000633:toxicity*; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D014820:Vitiligo / Q000473:pathology*; D000521:alpha-MSH / Q000494:pharmacology
D008543:Melanins; D051739:Microphthalmia-Associated Transcription Factor; D010636:Phenols; D012333:RNA, Messenger; D000521:alpha-MSH; D010088:Oxidoreductases; C064056:tyrosinase-related protein-1; C006862:butylphen