A dominant negative mutant of microphthalmia transcription factor (MITF) lacking two transactivation domains suppresses transcription mediated by wild type MITF and a hyperactive MITF derivative
Language English Country Denmark Media print
Document type Journal Article, Research Support, Non-U.S. Gov't
PubMed
14717844
DOI
10.1046/j.1600-0749.2003.00108.x
PII: 108
Knihovny.cz E-resources
- MeSH
- Transcriptional Activation physiology MeSH
- DNA-Binding Proteins genetics metabolism MeSH
- Genes, Dominant MeSH
- Transcription, Genetic physiology MeSH
- Herpes Simplex Virus Protein Vmw65 genetics metabolism MeSH
- Humans MeSH
- Mice MeSH
- Cell Line, Tumor MeSH
- Promoter Regions, Genetic physiology MeSH
- Gene Expression Regulation, Enzymologic physiology MeSH
- Recombinant Proteins genetics metabolism MeSH
- Suppression, Genetic physiology MeSH
- Protein Structure, Tertiary genetics physiology MeSH
- Microphthalmia-Associated Transcription Factor MeSH
- Transcription Factors genetics metabolism MeSH
- Monophenol Monooxygenase genetics metabolism MeSH
- Artificial Gene Fusion MeSH
- Genes, Viral genetics MeSH
- Animals MeSH
- Check Tag
- Humans MeSH
- Mice MeSH
- Animals MeSH
- Publication type
- Journal Article MeSH
- Research Support, Non-U.S. Gov't MeSH
- Names of Substances
- DNA-Binding Proteins MeSH
- Herpes Simplex Virus Protein Vmw65 MeSH
- MITF protein, human MeSH Browser
- Mitf protein, mouse MeSH Browser
- Recombinant Proteins MeSH
- Microphthalmia-Associated Transcription Factor MeSH
- Transcription Factors MeSH
- Monophenol Monooxygenase MeSH
Microphthalmia transcription factor (MITF) positively regulates transcription of differentiation-related genes in several cell lineages, including melanocytes. Recent data also indicate a new important role for MITF as a factor that appears to be required for survival of melanoma cells, suggesting a possibility that abrogation of MITF function in transformed melanocytes could lead to a decreased survival via attenuating anti-apoptotic signals. Therefore, to gain a better understanding of the role which MITF plays in melanoma cell survival, it is important to find efficient means of abolishing the transactivation of its target genes. Recently, a dominant negative MITF lacking the N-terminus has been shown to down-regulate tyrosinase and Trp1 expression in normal melanocytes and mouse B16 melanoma cells. Here, a dominant negative mutant of the melanocyte-specific isoform of MITF is described carrying deletions of both N- and C-terminal transactivation domains. Cotransfection of this mutant resulted in a complete inhibition of the wild type MITF function as tested on both the reporter-linked tyrosinase promoter and an endogenous, ectopic MITF-triggered tyrosinase gene in U2-OS cells. The dominant negative construct also strongly repressed the activity of a hyperactive MITF-Vp16 chimera. Importantly, deletion of both activation domains was necessary to eliminate the residual transcription activity observed when only the N-terminal domain was removed and to achieve the repressive effect in human melanoma cells. If the activity of MITF plays a role in the long-term survival of malignant melanocytes, overexpression of a strong dominant negative MITF mutant might be a useful strategy to suppress its transactivation function.
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