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.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors
  • Cloning, Molecular
  • DNA-Binding Proteins / chemistry*
  • Gene Expression Regulation / genetics
  • Humans
  • In Situ Hybridization
  • Membrane Glycoproteins*
  • Mice
  • Microphthalmia-Associated Transcription Factor
  • Molecular Sequence Data
  • Monophenol Monooxygenase / genetics
  • Neoplasm Proteins*
  • Oxidoreductases*
  • Pigment Epithelium of Eye / chemistry*
  • Proteins / genetics
  • RNA, Messenger / analysis
  • Sequence Analysis, DNA
  • Sequence Homology, Amino Acid
  • Transcription Factors / chemistry
  • Transcriptional Activation
  • Tumor Cells, Cultured


  • Basic Helix-Loop-Helix Leucine Zipper Transcription Factors
  • DNA-Binding Proteins
  • MITF protein, human
  • Membrane Glycoproteins
  • Microphthalmia-Associated Transcription Factor
  • Mitf protein, mouse
  • Neoplasm Proteins
  • Proteins
  • RNA, Messenger
  • TFEB protein, human
  • Transcription Factors
  • Oxidoreductases
  • TYRP1 protein, human
  • Tyrp1 protein, mouse
  • tyrosinase-related protein-1
  • Monophenol Monooxygenase

Associated data

  • GENBANK/AB006909
  • GENBANK/AB006989
  • GENBANK/AB009397