Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: EC:1.10.3.1 (tyrosinase)
 9,065 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

In this study, we used melb-a melanoblasts as a model to study mechanisms involved in stimulating melanocyte function in vitiliginous skin following exposure to 8-methoxypsoralen (8MOP). Melanin content and tyrosinase activity increased 3- and 7-fold, respectively, in melanoblasts treated with 8MOP for 6 d compared with untreated controls. The intracellular signal pathways involved in 8MOP-induced effects on melanoblasts were investigated, particularly the roles of protein kinase A and protein kinase C. Forskolin, a protein kinase A activator, mimicked and enhanced the 8MOP stimulation of melanoblast pigmentation whereas a protein kinase C activator, 1-oleoyl-2-acetylglycerol, had no effect, indicating that the protein kinase A pathway is involved rather than the protein kinase C pathway. Those observations were confirmed using inhibitors of the protein kinase A or protein kinase C pathways. Western blot and semiquantitative reverse transcriptase polymerase chain reaction were performed to assess the protein and mRNA expression levels of microphthalmia-associated transcription factor and tyrosinase in melanoblasts treated with 8MOP for 3 h, 6 h, 1 d, 3 d, or 6 d. Incubation with 8MOP stimulated microphthalmia-associated transcription factor protein and mRNA levels within 3 h, but, in contrast, tyrosinase mRNA and protein levels did not increase following 8MOP treatment until 1 d after treatment. The proteasome inhibitor lactacystin blocked the proteasome-mediated proteolysis of tyrosinase, and its effect on proteasomal function was enhanced by 8MOP. Taken together, these results show that 8MOP functions by initially stimulating levels of microphthalmia-associated transcription factor expression via activation of the protein kinase A pathway, which thereby stimulates tyrosinase expression and function and eventually leads to dramatic increases in melanin production by melanoblasts.
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PMID:Stimulation of melanoblast pigmentation by 8-methoxypsoralen:the involvement of microphthalmia-associated transcription factor, the protein kinase a signal pathway, and proteasome-mediated degradation. 1248 19

Microphthalmia transcription factor (Mitf) is implicated as the master gene for survival of melanocytes, as well as a key transcription factor regulating the expression of major melanogenic proteins. We have shown that Mitf is a novel prognostic marker in patients with melanoma and that it plays a role in melanoma differentiation. Melanocyte-stimulating hormone up-regulates Mitf expression. Forskolin is a known alpha-melanocyte-stimulating hormone agonist. This study was undertaken to determine if forskolin induces differentiation in UISO-Mel-6 cell lines. Forskolin inhibits cell proliferation and increases the expression of Mitf and tyrosinase related protein-1. It also increases extracellular melanin production. In addition, we showed by flow cytometry that forskolin decrease the number of cells in S-phase without engaging the cells in apoptosis. Our results suggest that Forskolin induces differentiation in melanoma cells via Mitf pathway.
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PMID:Induction of microphthalmia transcription factor (Mitf) by forskolin and stimulation of melanin release in UISO-Mel-6 cells. 1802 52