Functional analysis of microphthalmia-associated transcription factor in pigment cell-specific transcription of the human tyrosinase family genes.
Tyrosinase, tyrosinase-related protein-1 (TRP-1), and TRP-2 are the enzymes involved in melanin biosynthesis and are preferentially expressed in pigment cells. Their human gene promoters share the 11-base pair M box containing a CATGTG motif, which was shown here to be bound in vitro by microphthalmia-associated transcription factor (MITF). Transient cotransfection analysis showed that MITF overexpression increased the expression of a reporter gene under the control of the human tyrosinase or TRP-1 gene promoter but not the TRP-2 promoter. The promoter activation caused by MITF is dependent on each CATGTG motif of the distal enhancer element, the M box, and the initiator E box of the tyrosinase gene and the TRP-1 M box. Furthermore, a truncated MITF lacking the carboxyl-terminal 125 amino acid residues transactivated the tyrosinase promoter less efficiently than did MITF, suggesting that MITF's carboxyl terminus contains a transcriptional activation domain, but unexpectedly such a truncated MITF remarkably transactivated the TRP-2 gene promoter. These results suggest that MITF is sufficient to direct pigment cell-specific transcription of the tyrosinase and TRP-1 genes but not the TRP-2 gene.
Yasumoto
K
K
Department of Applied Physiology and Molecular Biology, Tohoku University School of Medicine, Aoba-ku, Sendai, Japan.
Yokoyama
K
K
Takahashi
K
K
Tomita
Y
Y
Shibahara
S
S
D001483:Base Sequence; D004268:DNA-Binding Proteins / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic; D006367:HeLa Cells; D006801:Humans; D007370:Interferon Type I / Q000235:genetics*; D019746:Intramolecular Oxidoreductases; D007535:Isomerases / Q000235:genetics*; D008562:Membrane Glycoproteins; D051739:Microphthalmia-Associated Transcription Factor; D008850:Microphthalmos / Q000235:genetics*; D008969:Molecular Sequence Data; D014442:Monophenol Monooxygenase / Q000235:genetics*; D016297:Mutagenesis, Site-Directed; D010088:Oxidoreductases; D011401:Promoter Regions, Genetic; D011506:Proteins / Q000235:genetics*; D012333:RNA, Messenger / Q000235:genetics; D013329:Structure-Activity Relationship; D014157:Transcription Factors; D014158:Transcription, Genetic; D015533:Transcriptional Activation
D004268:DNA-Binding Proteins; D007370:Interferon Type I; C497234:MITF protein, human; D008562:Membrane Glycoproteins; D051739:Microphthalmia-Associated Transcription Factor; D011506:Proteins; D012333:RNA, Messenger; D014157:Transcription Factors; D010088:Oxidoreductases; C489799:TYRP1 protein, human; C064056:tyrosinase-related protein-1; D014442:Monophenol Monooxygenase; D007535:Isomerases; D019746:Intramolecular Oxidoreductases; C042501:dopachrome isomerase