Molecular cloning of cDNA encoding a human TFEC isoform, a newly identified transcriptional regulator.
TFEC is a transcriptional repressor originally identified in rat chondrosarcoma and contains a basic helix-loop-helix and leucine zipper (bHLH/LZ) structure. TFEC shares a closely related bHLH/LZ structure with microphthalmia-associated transcription factor (MITF) and TFE3. In the course of cDNA cloning for a factor structurally related to MITF which is also a regulator for cell differentiation, we have isolated cDNA clones from a THP-1 human monocytic leukemia cell line. These cDNAs encode a protein of 347 amino acids, termed TFECL, a human homolog of a putative rat TFEC isoform. TFECL contains an acidic domain that corresponds to a transcriptional activation domain of TFE3 but its equivalent region is deleted in rat TFEC. We explored a function of TFECL using a melanocyte-specific tyrosinase gene and a ubiquitously expressed heme oxygenase-1 gene, each promoter containing the cis-acting CANNTG motifs. By transient coexpression assays, we showed that TFECL is able to activate or inhibit transcription of a reporter gene linked to either the tyrosinase or the heme oxygenase-1 gene promoter, depending on cell types. These results suggest that TFECL may function as a transcriptional activator under certain conditions.
Yasumoto
K
K
Department of Applied Physiology and Molecular Biology, Tohoku University School of Medicine, Sendai, Miyagi, Japan.
Shibahara
S
S
D000595:Amino Acid Sequence; D001483:Base Sequence; D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D003001:Cloning, Molecular; D018076:DNA, Complementary / Q000235:genetics*; D004268:DNA-Binding Proteins / Q000235:genetics*; D006801:Humans; D051739:Microphthalmia-Associated Transcription Factor; D008969:Molecular Sequence Data; D014157:Transcription Factors / Q000235:genetics*; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
D051778:Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; D018076:DNA, Complementary; D004268:DNA-Binding Proteins; C497234:MITF protein, human; D051739:Microphthalmia-Associated Transcription Factor; C069203:TFE3 protein, human; C082272:TFEC protein, human; D014157:Transcription Factors