Sticky fingers at work: Palmitoylation-dependent MC1R activation

Pharmacologic manipulation of skin pigmentation

Skin complexion is among the most recognizable phenotypes between individuals and is mainly determined by the amount and type of melanin pigment deposited in the epidermis. Persons with dark skin complexion have more of a brown/black pigment known as eumelanin in their epidermis whereas those with fair skin complexions have less. Epidermal eumelanin acts as a natural sunblock by preventing incoming UV photons from penetrating into the skin and therefore protects against UV mutagenesis. By understanding the signaling pathways and regulation of pigmentation, strategies can be developed to manipulate skin pigmentation to improve UV resistance and to diminish skin cancer risk.

Ultraviolet Radiation and Melanomagenesis: From Mechanism to Immunotherapy

Melanoma is the deadliest form of skin cancer, and nearly 90% of melanomas are believed to be caused by ultraviolet radiation (UVR), mainly from sunlight. UVR induces DNA damage, forming products such as cyclobutane pyrimidine dimers (CPD) and 6-4-pyrimidone photoproducts (6-4PP) in a wavelength-dependent manner and causes oxidative DNA damage. These DNA lesions lead to DNA mutations and contribute to the formation of melanoma. In this review, we discuss the protective role of melanocytes against UV-induced DNA damage and how genetic variations, including those in p53 and melanocortin-1 receptor (MC1R), or epigenetic histone modifications in melanocytes result in a tendency toward melanoma. We also provide a summary of prevention and treatment strategies against melanoma, including the most recent immunotherapies. Collectively, this work contributes to the understanding of the molecular pathogenesis of UV-induced melanoma.

Effect of polysaccharide FMP-1 from Morchella esculenta on melanogenesis in B16F10 cells and zebrafish

Polysaccharides from Morchella esculenta are known to exhibit diverse bioactivities, while an anti-melanogenesis effect has been barely addressed. Herein, the anti-melanogenesis activity of a heteropolysaccharide from M. esculenta (FMP-1) was investigated in vitro and in vivo. FMP-1 had no significant cytotoxic effect on B16F10 melanoma cells as well as zebrafish larvae, but did reduce melanin contents and tyrosinase activities in both of them. Treatment with FMP-1 also effectively suppressed the expression of melanogenesis-related proteins, including MC1R, MITF, TRP-1 and TRP-2, through decreasing the phosphorylation of cyclic adenosine monophosphate response element-binding protein (CREB). Moreover, the mitogen-activated protein kinase (MAPK) pathway was observed mediating FMP-1's inhibitory effect against melanin production. Specifically, FMP-1 treatment markedly inhibited the activation of phosphorylation of p38 mitogen-activated protein kinase. These results suggested that FMP-1's inhibitory effect against melanogenesis is mediated by the inhibition of CREB and p38 signaling pathways, thereby resulting in the downstream repression of melanogenesis-related proteins and the subsequent melanin production. These data provide insight into FMP-1's potential anti-melanogenesis effect in food and cosmetic industries.