Fol. Biol. 2006, 52, 161-166
Distinct Co-regulation of Endogenous versus Transfected MITF-Dependent Tyrosinase Promoter
The tissue-specific control of gene activation in melanocytes is directed by the microphthalmia-associated transcription factor (MITF), a master regulator of melanocyte development and differentiation. Tyrosinase is a rate-limiting enzyme in melanin biosynthesis and a prototypic MITF target. While the expression of tyrosinase is restricted to pigmented cells, the transfected tyrosinase promoter is active in a broad range of cell types if ectopic MITF is co-expressed. Here we used the E1A oncoprotein and its mutants as repressors of both the transiently transfected and endogenous tyrosinase promoter. We report that the requirement of the E1A N-terminus for repression of the MITF-activated tyrosinase promoter and the sensitivity to derepression by the histone deacetylase inhibitor trichostatin A are distinct when the activity of the transiently transfected or the endogenous promoter is analysed in U2-OS cells. Thus, for transiently transfected versus chromatin-embedded promoter, the activity of obligatory MITF seems to be executed through different mechanisms of transcriptional coactivation.
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Funding
This work is supported by grant from IGA NR/8026-3 and in part by the institutional research project MZO00064211 from the Ministry of Health, Czech Republic.
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This is an open-access article distributed under the terms of the Creative Commons Attribution License.