Absence of TRP‐2 in Melanogenic Melanocytes of Human Hair

Abstract

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.

Age‐induced hair greying – the multiple effects of oxidative stress

“…Indeed, individuals with grey and white scalp hairs have much reduced greying at their eyelashes and eyebrows, suggesting possible differences between hair follicles of these locations. TRP-2 is expressed in eyelash and eyebrow bulbar melanocytes, whereas it is absent from the scalp hair bulb melanocytes of same individuals [82][83][84]. More studies are needed to better understand the differences between hair follicles of different locations in relation to their protection from the loss of pigment production.…”

Anisaldehyde, a Melanogenesis Potentiator

“…Thus, anisaldehyde is capable of protecting from human skin damage (Shoji et al, 1997), for example by UV irradiation (Eller et al, 1994). The same concept may be applicable to develop an anti-white hair agent, although hair pigmentation involves complex biochemical reactions (Fitzpatrick et al, 1967;Commo et al, 2004). The fact that anisaldehyde was characterized from many edible plants as a flavor substance should cause it to be superior compared to nonnatural melanogenesis enhancing agents.…”

Eyelashes: Anatomical and Physiological Features, Eyelash Loss and Trichomegaly: Review

“…5 Yakın zamanlı bir çalışmada, kirpik melanositlerinde TRP-2'nin yoğun eksprese edildiği ve bu yüzden de kirpiklerin yaşa bağlı beyazlamadığı gösterilmiştir. 2 Son yıllarda, dış kök kılıfında yer alan epidermal büyüme faktör reseptörleri (EGFR)'nin kıl bü-yümesinde kritik role sahip olduğu gösterilmiştir.…”