Studies On The Effects Of Natural Chemicals To The Melanogenesis And Activation And Migration Of Amelanotic Melanocytes In Outer Root Shealth Of The Hair Follocles

Melanocyte, possessing the specialized cytoplasmic organization and the biosynthetic apparatus to generate melanin, is a kind of dendritic cell derived from neural crest. The quantity and quality of melanin are the main determination of skin color. Melanin may be either brown-black (eumelanin) or yellow-red (pheomelanin), whose pigmentation in human skin can be divided into constitutive and facultative skin colors. Constitutive, or intrinsic, skin color is a genetically determined degree of cutaneous melanin pigmentation, which is present independent of outside influences. Facultative skin color represents the increased melanin pigmentation above that of the constitutive level; and other environmental factors upon the individual's genetically endowed melanogenic potential.Production of melanin is one of the most well known differentication features of melanocytes, which is a process consistes of many steps of biochemical enzyme-catalyzed reactions and is regulated complicated and precised. The process of the melanogenesis may be summarized in ninestages difined as follows:(1)Migration of pigment cell precursors from the neural crest. (2)Clonal population of skin by melanocytes. (3)Induction of melanogenic genes, including tyrosinase, tyrosinase related protein and melanosomal matrix components. (4)Synthesis of tyrosinase and related melanogenic proteins. (5)Posttranslational processing and glycosylation of tyrosinase. (6)Fusion of vesicles to form melanosomes and initiation of melanogenesis. (7)Control of tyrosinase activity and activity of tyosinase related proteins. (8)Posttyrosinase modification of biosythesis. (9)Modification of melanin. Hypopigmentation or hyperpigmentation may arise from interference with any of these processes. To updata, the investigation about melanogenesis almost developed underneath synthesis of tyrosinase and related mlanogenic proteins. Tyrosinase activity is a key determinant of melanin production in the skin. This enzyme catalysis the early rate-limiting steps of the biosynthetic pathway of melanin: the hydroxylation of tyrosine and the oxidation of dopa. Moreover, the rate of melanin synthesis is correlated with the amount and activity of tyrosinase in the cells. In addition, a positive relationship exists between human skin color and the activity of this enzyme. Melanin production appears to be regulated by a subtle balance between positive (tyrosinase, TRP-1 and TRP-2) and negative (melanogenic inhibitors) melanogenic factors. TRP-1 shares thetwo catalytic properties ascribed to tyrosinase. TRP-2 catalyzes the conversion of DOPAchrome to DHICA (5,6-dihydroxyindole-2-carboxylic acid) and seems to play a key role in the control of the distal steps of the melaninpathway synthesis. In our last researchs, we found some Chinese herbs can increase the activity of tyrosinase in vitro. To further study the melanogenesis action and mechanism of those herbs, we applied some nature chemicals from Chinese traditional medicine and observe their roles on Cloudman S91 melanoma cells and melanocytes from human epidermis. We hope to select a safe and most effective nature chemical for the future treatment of pigmented skin disease.Vitiligo is an acquired melanin pigmentary disorder manifesting itself by expanding depigmented lesions of the skin. Pathologically, absence of melanin and melanocytes from affected epidermis and degeneration of melanocytes and basal keratinocytes are observed in patients with vitiligo. Repigmentation of vitiligo is usually seen in a perifollicular manner. During this process it is thought that amelanotic melanocytes of outer root shealth in human hair follicle often act as a reservoir population of melanocytes. It become activates, proliferate and migrate into depigmented epidermis underneath some stimulator such as radiation with ultraviolet A and narrow-band ultraviolet B,psoralen-ultraviolet A, local applying with cortico steroid and tretinoin. However, the pathogenesis is still not known. It has been reported that some cytokins secreted from keratinocytes around...