Mechanisms of skin tanning in different racial/ethnic groups in response to ultraviolet radiation.

Ultraviolet radiation stimulates pigmentation in human skin, but the mechanism(s) whereby this increase in melanin production (commonly known as tanning) occurs is not well understood. Few studies have examined the molecular consequences of UV on human skin of various racial backgrounds in situ. We investigated the effects of UV on human skin of various races before and at different times after a single 1 minimal erythemal dose UV exposure. We measured the distribution of DNA damage that results, as well as the melanin content/distribution and the expression of various melanocyte-specific genes. The density of melanocytes at the epidermal:dermal junction in different types of human skin are remarkably similar and do not change significantly within 1 wk after UV exposure. The expression of melanocyte-specific proteins (including TYR (tyrosinase), TYRP1 (tyrosinase-related protein 1), DCT (tyrosinase-related protein 2), MART1 (melanoma antigens recognized by T-cells) gp100 (Pmel17/silver), and MITF (micropthalmia transcription factor)) increased from 0 to 7 d after UV exposure, but the melanin content of the skin increased only slightly. The most significant change, however, was a change in the distribution of melanin from the lower layer upwards to the middle layer of the skin, which was more dramatic in the darker skin. These results provide a basis for understanding the origin of different skin colors and responses to UV within different races.

[1]  S Shibahara,et al.  Regulation of pigment cell-specific gene expression by MITF. , 2000, Pigment cell research.

[2]  G. Barsh,et al.  The melanocortin 1 receptor is the principal mediator of the effects of agouti signaling protein on mammalian melanocytes. , 2001, Journal of cell science.

[3]  J. Bancroft,et al.  Theory and Practice of Histological Techniques , 1990 .

[4]  Sharon A Miller,et al.  UV‐induced DNA damage and melanin content in human skin differing in racial/ethnic origin , 2003, FASEB journal : official publication of the Federation of American Societies for Experimental Biology.

[5]  T. Downie,et al.  Theory and Practice of Histological Techniques Edited by J.D. Bancroft & A. Stevens, Churchill Livingstone, Edinburgh, 740 pages, £55.00 , 1990 .

[6]  V. Ferrans,et al.  Influence of α‐melanocyte‐stimulating hormone and of ultraviolet radiation on the transfer of melanosomes to keratinocytes , 2002, FASEB journal : official publication of the Federation of American Societies for Experimental Biology.

[7]  B L Diffey,et al.  The standard erythema dose: a new photobiological concept , 1997, Photodermatology, photoimmunology & photomedicine.

[8]  Thomas B. Fitzpatrick,et al.  Dermatology in general medicine , 1971 .

[9]  S. Alaluf,et al.  The impact of epidermal melanin on objective measurements of human skin colour. , 2002, Pigment cell research.

[10]  D. Whiteman,et al.  Determinants of melanocyte density in adult human skin , 1999, Archives of Dermatological Research.

[11]  S. Jee,et al.  The patterns of melanosome distribution in keratinocytes of human skin as one determining factor of skin colour , 2003, The British journal of dermatology.

[12]  V. Hearing,et al.  Specific identification of an authentic clone for mammalian tyrosinase. , 1989, The Journal of biological chemistry.

[13]  J. Nordlund.  The pigmentary system : physiology and pathophysiology , 1998 .

[14]  R. Halder,et al.  Skin cancer in African Americans , 1995, Cancer.

[15]  G. Barsh,et al.  Modulation of murine melanocyte function in vitro by agouti signal protein , 1997, The EMBO journal.

[16]  R. Stern,et al.  Nonmelanoma cancers of the skin. , 1992, The New England journal of medicine.

[17]  B. Kågedal,et al.  UVB irradiation induces melanocyte increase in both exposed and shielded human skin. , 1989, The Journal of investigative dermatology.

[18]  W S Oetting,et al.  The tyrosinase gene and oculocutaneous albinism type 1 (OCA1): A model for understanding the molecular biology of melanin formation. , 2000, Pigment cell research.

[19]  V. Hearing,et al.  The Seiji memorial lecture: the melanosome: an ideal model to study cellular differentiation. , 2003, Pigment cell research.

[20]  Kazuhiro Takahashi,et al.  Microphthalmia‐associated transcription factor interacts with LEF‐1, a mediator of Wnt signaling , 2002, The EMBO journal.

[21]  K Takahashi,et al.  Microphthalmia-associated transcription factor (MITF): multiplicity in structure, function, and regulation. , 2001, The journal of investigative dermatology. Symposium proceedings.

[22]  Bruce K. Armstrong,et al.  Sun exposure and non-melanocytic skin cancer , 1994, Cancer Causes & Control.

[23]  Li Jin,et al.  Skin pigmentation, biogeographical ancestry and admixture mapping , 2003, Human Genetics.

[24]  W. C. Quevedo,et al.  General Biology of Mammalian Pigmentation , 2007 .

[25]  V. Ferrans,et al.  Production of melanocyte-specific antibodies to human melanosomal proteins: expression patterns in normal human skin and in cutaneous pigmented lesions. , 2001, Pigment cell research.

[26]  N. Kollias,et al.  Minimum erythema dose determination in individuals of skin type V and VI with diffuse reflectance spectroscopy. , 1994, Photodermatology, photoimmunology & photomedicine.

[27]  S. Ramaswamy,et al.  MLANA/MART1 and SILV/PMEL17/GP100 are transcriptionally regulated by MITF in melanocytes and melanoma. , 2003, The American journal of pathology.

[28]  H. Maibach,et al.  Pigmentation and Pigmentary Disorders , 1993 .

[29]  M. Tachibana,et al.  MITF: a stream flowing for pigment cells. , 2000, Pigment cell research.

[30]  B. Fuller,et al.  Regulation of the catalytic activity of preexisting tyrosinase in black and Caucasian human melanocyte cell cultures. , 2001, Experimental cell research.

[31]  E. Appella,et al.  A model for melanosome biogenesis based on the purification and analysis of early melanosomes , 2001, Proceedings of the National Academy of Sciences of the United States of America.