Oral communication, S5 Fitzpatrick Lecture

Official XXIst International Pigment Cell Conference website - 21-24 Sept 2011, Bordeaux - France | updated: September 04 2011

Functionally distinct melanocyte populations revealed in mice: noncutaneous and dermal melanocytes versus epidermal melanocytes

Unlike the thoroughly investigated melanocyte population in the hair follicle of the epidermis, the growth and differentiation requirements of the melanocytes in the eye, harderian gland and inner ear – the so-called non-cutaneous melanocytes – remain unclear. By using hair follicle reconstitution analysis, we confirmed the inability of dermal or non-cutaneous melanocytes to be involved as follicular melanocytes to regenerating hair follicles during hair reconstitution assay. To investigate a molecular basis of the functional difference, we investigated the in vitro and in vivo effects of the factors that regulate melanocyte development on the stem cells or the precursors of these non-cutaneous melanocytes. Melanocytes in the eye, ear and harderian gland were revealed to be less sensitive to KIT signaling than cutaneous melanocytes. Instead, melanocytes in the eye and harderian gland were stimulated more effectively by endothelin 3 (ET3) or hepatocyte growth factor (HGF) signals than by KIT signaling, and the precursors of these melanocytes expressed the lowest amount of KIT. In transgenic mice induced to express ET3 or HGF in their skin and epithelial tissues from human cytokeratin 14 promoters, the survival and differentiation of non-cutaneous and dermal melanocytes, but not epidermal melanocytes, were enhanced, apparently irrespective of KIT signaling. Thus revealed clear discrimination between non-cutaneous or dermal melanocytes and epidermal melanocytes might be important in the pathogenesis of melanocyte-related diseases and melanomas.

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