Composition of Mammalian Eumelanins: Analyses of DHICA‐Derived Units in Pigments From Hair and Melanoma Cells

Wilczek, Adam; Kondoh, Hirofumi; Mishima, Yutaka

doi:10.1111/j.1600-0749.1996.tb00090.x

Cited by 25 publications

(16 citation statements)

References 19 publications

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“…In contrast, pheomelanin is present at comparatively low levels in these skin types ( 2-8%). While this kind of precise compositional breakdown for human epidermal melanin has not previously been reported in the literature, the data are consistent with earlier findings by Wilczek et al (28), who used a similar combination of spectrophotometric and HPLC methods to show approximately 19-23% DHICA content in the melanin from dark brown and black human hair.…”

Section: Discussionsupporting

confidence: 91%

“…Another likely source of error in this experiment comes from the assumption that yields of PTCA and AHP/AT from DHICA-eumelanin and pheomelanin are consistently 2 and 20%, respectively, in all skin samples examined. The value of 2% is consistent with the yield of PTCA previously reported for a sepia melanin and a pure DHICA melanin standard (21,28). However, we accept that this is probably an average approximation, and that the yield of PTCA actually varies in different samples by as much as 91% (unpublished observations).…”

Section: Discussionsupporting

confidence: 90%

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Variation in Melanin Content and Composition in Type V and VI Photoexposed and Photoprotected Human Skin: The Dominant Role of DHI

Alaluf

Heath

Carter

et al. 2001

Pigment Cell Research

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A combination of techniques, including high-performance liquid chromatography (HPLC), spectrophotometric measurements, and a novel method for quantifying melanosome morphology, were applied to the analysis of melanin content and composition in highly pigmented (Fitzpatrick type V and VI) human skin. We found that total epidermal melanin content is significantly elevated in photoexposed type V and VI skin (approximately 1.6 x), while analysis of individual melanin components suggests that pheomelanin content increases only slightly, whereas 5,6-dihydroxyindole-2-carboxylic acid (DHICA)-eumelanin and to a greater extent 5,6-dihydroxyindole (DHI)-eumelanin content are both markedly elevated. Analysis of the relative composition of epidermal melanin in these subjects revealed that DHI-eumelanin is the largest single component (approximately 60-70%), followed by DHICA-eumelanin (25-35%), with pheomelanin being a relatively minor component (2-8%). Moreover, there was a comparative enrichment of DHI-eumelanin at photoexposed sites, with a corresponding decline in the relative contributions from DHICA-eumelanin and pheomelanin. There was also a good correlation and close agreement between the concentration of spheroidal melanosomes determined by morphological image analysis and the concentration of pheomelanin determined by a combination of HPLC and spectrophotometric analysis (r = 0.89, P < 0.02). This study demonstrates the usefulness of melanosome morphology analysis as a sensitive new method for the quantification of melanin composition in human skin. The data also suggest that DHI-eumelanin formation is the dominant pathway for melanin synthesis in heavily pigmented (Fitzpatrick V and VI) skin types in vivo, and is the favoured pathway when melanin production is increased in chronically photoexposed skin.

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Section: Discussionsupporting

confidence: 91%

Section: Discussionsupporting

confidence: 90%

Variation in Melanin Content and Composition in Type V and VI Photoexposed and Photoprotected Human Skin: The Dominant Role of DHI

Alaluf

Heath

Carter

et al. 2001

Pigment Cell Research

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“…However, the absence of TRP‐2 in human eumelanic hair bulbs supports the recent finding that melanins of human eumelanic hairs contain low yield of DHICA‐melanins as compared with other mammalian eumelanic hairs e.g. mice, hamster and sheep (24, 49, 50).…”

Section: Discussionsupporting

confidence: 72%

Absence of TRP‐2 in Melanogenic Melanocytes of Human Hair

Commo

Gaillard

Thibaut

et al. 2004

Pigment Cell Research

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Skin and hair colour mostly depend on the activity of melanogenic melanocytes. Numerous proteins involved in melanocyte function have been identified including pMel-17, Mitf-M, Sox10, tyrosinase, tyrosinase related proteins-1 (TRP-1) and -2 (TRP-2). In the hair, melanogenic activity occurs only during the anagen phase of the hair cycle. In order to evaluate the implications of some known melanogenic proteins in human hair pigmentation, we performed immunohistochemical studies to reveal the expression of pMel-17, Mitf-M, tyrosinase, TRP-1 and TRP-2 in active bulb melanocytes of eumelanic brown and black anagen hairs of different ethnic origins, e.g. brown Caucasian, black Asian and African hairs. The labelling was compared with that observed in Caucasian and African scalp epidermis (interfollicular epidermis) melanocytes. We found that while pMel-17, TRP-1 and TRP-2 were expressed in epidermal melanocytes irrespective of ethnic origin and melanin content of the scalp epidermis, Mitf-M and tyrosinase expression were clearly evidenced only in pigmented epidermis, e.g. African scalps. Regarding human hair, pMel-17, Mitf-M, tyrosinase and TRP-1 were detected in a similar manner in active bulb melanocytes of brown and black hairs. In contrast and unexpectedly, TRP-2 could not be detected in hair bulb melanocytes, whatever the hair colour and ethnic origin. The lack of TRP-2 was further confirmed by western blot analyses. Reverse transcriptase-polymerase chain reaction (RT-PCR) performed on hair bulb mRNA demonstrated that Mitf-M, tyrosinase and TRP-1 amplimer signals were easily detected, whereas the TRP-2 amplimer signal was barely detectable. Furthermore Sox10 was not detected in hair bulb. Altogether our results suggest that the absence of detectable level of TRP-2 is due to transcriptional control in active melanocytes of human eumelanic hair bulbs. According to the absence of TRP-2 in melanin-producing melanocytes of brown and black hair bulbs, one must consider that eumelanogenesis as well as brown and black colour do not require TRP-2 expression in human hair.

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“…11). Further, we found that the proportion of DHICA-derived units in mammalian eumelanin from hair and melanoma cells to be much higher in rodent pigment compared with human eumelanin (87).…”

Section: Mishima Institute Formentioning

confidence: 74%

Composition of Mammalian Eumelanins: Analyses of DHICA‐Derived Units in Pigments From Hair and Melanoma Cells

Cited by 25 publications

References 19 publications

Variation in Melanin Content and Composition in Type V and VI Photoexposed and Photoprotected Human Skin: The Dominant Role of DHI

Variation in Melanin Content and Composition in Type V and VI Photoexposed and Photoprotected Human Skin: The Dominant Role of DHI

Absence of TRP‐2 in Melanogenic Melanocytes of Human Hair

New Era of Cell Re‐Discovery Led to the Control of Melanogenesis/Melanoma: A Scientific Journey into Terra Incognita

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