Identification of a novel isoform of microphthalmia-associated transcription factor that is enriched in retinal pigment epithelium.
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Amae S, Fuse N, Yasumoto K, Sato S, Yajima I, Yamamoto H, Udono T, Durlu YK, Tamai M, Takahashi K, Shibahara S
Identification of a novel isoform of microphthalmia-associated transcription factor that is enriched in retinal pigment epithelium.
Biochem Biophys Res Commun. 1998 Jun 29;247(3):710-5. doi: 10.1006/bbrc.1998.8838.
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- 9647758 [ View in PubMed]
- Abstract
Mutations at the mouse locus encoding microphthalmia-associated transcription factor (Mitf) affect the development of many cell types, including retinal pigment epithelium (RPE), melanocytes, mast cells, and osteoclasts. Here we have identified a novel Mitf isoform, Mitf-a, and its human homologue MITF-A by cDNA cloning. MITF-A consists of 520 amino acid residues and differs in the amino-terminus from authentic melanocyte-type MITF (MITF-M). MITF-A mRNA is widely expressed and represents a predominant MITF isoform in cultured RPE cells, whereas MITF-M mRNA is exclusively expressed in melanocytes and melanoma cells. In situ hybridization analysis suggested that Mitf-a mRNA is enriched in the prospective RPE of mouse embryo. Moreover, transient cotransfection assays suggested that MITF-A activated transcription of the tyrosinase and tyrosinase-related protein 1 genes. MITF-A/Mitf-a therefore may play an important role in melanogenesis in RPE.