title: The essential role of p53 in hyperpigmentation of the skin via regulation of paracrine melanogenic cytokine receptor signaling.
abstract: Hyperpigmentation of the skin is characterized by increases in melanin synthesis and deposition. Although considered a significant psychosocial distress, little is known about the detailed mechanisms of hyperpigmentation. Recently, the tumor suppressor protein p53 has been demonstrated to promote ultraviolet B-induced skin pigmentation by stimulating the transcription of a melanogenic cytokine, POMC (pro-opiomelanocortin), in keratinocytes. Given that p53 can be activated by various kinds of diverse stresses, including sun exposure, inflammation, and aging, this finding led us to examine the involvement of p53 in cytokine receptor signaling, which might result in skin hyperpigmentation. Immunohistochemical and reverse transcription-PCR analyses revealed the increased expression and phosphorylation of p53 in the epidermis of hyperpigmented spots, accompanied by the higher expression of melanogenic cytokines, including stem cell factor, endothelin-1, and POMC. The involvement of p53 in hyperpigmentation was also indicated by the significantly higher expression of p53 transcriptional targets in the epidermis of hyperpigmented spots. Treatment of human keratinocytes and melanocytes with known p53 activators or inhibitors, including pifithrin-alpha (PFT), demonstrated significant increases or decreases, respectively, in the expression of melanogenic factors, including cytokines and their receptors. Additionally, PFT administration abolished stem cell factor-induced phosphorylation of mitogen-activated protein kinase in human melanocytes. Furthermore, when organ-cultured hyperpigmented spots, in vitro human skin substitutes, and mouse skin were treated with PFT or p53 small interfering RNA, the expression of melanogenic cytokines and their receptors was significantly decreased, as were levels of tyrosinase and melanogenesis. Taken together, these data reveal the essential role of p53 in hyperpigmentation of the skin via the regulation of paracrine-cytokine signaling, both in keratinocytes and in melanocytes.
authors.affiliation: Kao Biological Science Laboratories, Haga, Tochigi 321-3497, Japan.
authors.forename: Daiki
authors.initials: D
authors.lastname: Murase
authors.forename: Akira
authors.initials: A
authors.lastname: Hachiya
authors.forename: Yasuko
authors.initials: Y
authors.lastname: Amano
authors.forename: Atsushi
authors.initials: A
authors.lastname: Ohuchi
authors.forename: Takashi
authors.initials: T
authors.lastname: Kitahara
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Takema
mesh_terms: D000375:Aging / Q000187:drug effects / Q000378:metabolism / Q000528:radiation effects; D000818:Animals; D052160:Benzothiazoles / Q000494:pharmacology; D016207:Cytokines / Q000378:metabolism*; D000078404:Epidermal Cells; D004817:Epidermis / Q000378:metabolism*; D005260:Female; D005786:Gene Expression Regulation / Q000187:drug effects / Q000528:radiation effects; D006801:Humans; D007249:Inflammation / Q000378:metabolism; D015603:Keratinocytes / Q000166:cytology / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000528:radiation effects*; D008543:Melanins / Q000096:biosynthesis*; D008544:Melanocytes / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D008875:Middle Aged; D019899:Paracrine Communication / Q000187:drug effects / Q000528:radiation effects*; D011333:Pro-Opiomelanocortin / Q000096:biosynthesis*; D018121:Receptors, Cytokine; D012880:Skin Pigmentation / Q000187:drug effects / Q000528:radiation effects*; D014050:Toluene / Q000031:analogs & derivatives / Q000494:pharmacology; D014158:Transcription, Genetic / Q000187:drug effects / Q000528:radiation effects; D016159:Tumor Suppressor Protein p53 / Q000819:agonists / Q000037:antagonists & inhibitors / Q000378:metabolism*; D014466:Ultraviolet Rays
chemical_list: D052160:Benzothiazoles; D016207:Cytokines; D008543:Melanins; D018121:Receptors, Cytokine; C495901:TP53 protein, human; D016159:Tumor Suppressor Protein p53; D014050:Toluene; D011333:Pro-Opiomelanocortin; C121565:pifithrin