MITF-CM, a newly identified isoform of microphthalmia-associated transcription factor, is expressed in cultured mast cells

M. Shiohara, T. Shigemura, T. Suzuki, M. Tanaka, E. Morii, H. Ohtsu, S. Shibahara, K. Koike

Research output: Contribution to journalArticlepeer-review

5 Citations (Scopus)

Abstract

The microphthalmia-associated transcription factor (MITF) gene encodes a basic helix-loop-helix and leucin zipper protein. In this study, we identified a novel MITF isoform, MITF-CM, which possesses a unique amino terminus. Exon 1CM is located 84 kb upstream of the exon encoding the B1b domain. MITF-CM was expressed in the human mast cell line HMC-1, the human basophilic cell line KU812, and CB-derived mast cells cultured for 10 weeks as well as bone marrow mononuclear cells. Transient transfection of MITF-CM cDNA in COS-7 cells resulted in the expression of a 64-kDa protein, detected by Western blotting, and nuclear localization of the protein, detected by immunostaining. The transient cotransfection of a luciferase construct under the control of the tyrosinase promoter and MITF-CM cDNA increased luciferase activity threefold. In contrast, none of the MITF isoforms transactivated both the tryptase and chymase gene promoters, indicating differences in the gene transactivation system between humans and mice.

Original languageEnglish
Pages (from-to)215-226
Number of pages12
JournalInternational Journal of Laboratory Hematology
Volume31
Issue number2
DOIs
Publication statusPublished - 2009 Apr

Keywords

  • Cultured mast cells
  • Microphthalmia-associated transcription factor
  • Tryptase
  • Tyrosinase

ASJC Scopus subject areas

  • Hematology
  • Clinical Biochemistry
  • Biochemistry, medical

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