Induction of melanocyte-specific microphthalmia-associated transcription factor by Wnt-3a

J Biol Chem. 2000 May 12;275(19):14013-6. doi: 10.1074/jbc.c000113200.

Abstract

Microphthalmia-associated transcription factor (Mitf) plays a critical role in the development of neural crest-derived melanocytes. Here, we show that exogenously added Wnt-3a protein, an intercellular signaling molecule, up-regulates the expression of endogenous melanocyte-specific Mitf (Mitf-M) mRNA in cultured melanocytes. The melanocyte-specific promoter of the human MITF gene (MITF-M promoter) contains a functional LEF-1-binding site, which is bound in vitro by LEF-1 and confers the preferential expression on a reporter gene in melanocytes and melanoma cells, as judged by the transient transfection assays. Moreover, the LEF-1-binding site is required for the transactivation of a reporter gene by LEF-1, beta-catenin, or their combination. Exogenously added Wnt-3a protein also transactivates the MITF-M promoter via the LEF-1-binding site; this activation was abolished when a dominant-negative form of LEF-1 was coexpressed. These results suggest that Wnt-3a signaling recruits beta-catenin and LEF-1 to the LEF-1-binding site of the MITF-M promoter. Therefore, the present study identifies Mitf-M/MITF-M as a direct target of Wnt signaling.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Base Sequence
  • Cells, Cultured
  • DNA
  • DNA-Binding Proteins / genetics
  • Eye Abnormalities / genetics*
  • Gene Expression Regulation, Developmental / physiology
  • Humans
  • Melanocytes / metabolism*
  • Microphthalmia-Associated Transcription Factor
  • Promoter Regions, Genetic
  • Proteins / metabolism
  • Proteins / physiology*
  • Signal Transduction
  • Transcription Factors / metabolism
  • Transcription Factors / physiology*
  • Wnt Proteins
  • Wnt3 Protein
  • Wnt3A Protein

Substances

  • DNA-Binding Proteins
  • MITF protein, human
  • Microphthalmia-Associated Transcription Factor
  • Proteins
  • Transcription Factors
  • WNT3A protein, human
  • Wnt Proteins
  • Wnt3 Protein
  • Wnt3A Protein
  • DNA