Transcriptional regulation of c-Fes in myeloid leukemia cells.
The c-Fes proto-oncogene encodes a myeloid-specific protein-tyrosine kinase that is expressed preferentially in differentiated myeloid cells, but not in early myeloblast progenitor cells. To examine the basis for the phenotypic expression of c-Fes, the transcription initiation sites of the human c-Fes gene were mapped in myeloid leukemia cells and regulatory elements in the genomic c-Fes sequence were characterized. Two major transcription initiation sites were found in the myeloid leukemia cell line THP-1 which delineated exon 1 to be 72-83 bp. When the activity of the CAT reporter gene under the control of the c-Fes promoter region, untranslated exon 1 and intron 1 was measured in TF-1, K562 and MCF-7 cells, only TF-1 cells exhibited chloramphenicol acetyltransferase activity. In contrast, all cell lines supported reporter gene activity when intron 1 was deleted. Deletion analyses revealed a negative regulatory region in intron 1, which was localized by Southwestern analysis and DNA footprinting to a 14 bp region. This negative regulatory region suppressed reporter CAT activity in K562 and TF-1 cells when inserted downstream to the SV40 early promoter. These results suggest that the tissue-specific expression of c-Fes may result, in part, from the negative regulation of transcription in myeloid and nonmyeloid cells.
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Department of Pharmacology, Georgetown University Medical Center, Washington, DC 20007, USA.
Borellini
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F
Koch
W H
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Huang
K X
KX
Glazer
R I
RI
D001483:Base Sequence; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D018983:DNA Footprinting; D017931:DNA Primers; D006801:Humans; D007438:Introns; D015464:Leukemia, Myelogenous, Chronic, BCR-ABL Positive / Q000235:genetics*; D008969:Molecular Sequence Data; D011505:Protein-Tyrosine Kinases; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins / Q000235:genetics*; D051578:Proto-Oncogene Proteins c-fes; D012045:Regulatory Sequences, Nucleic Acid; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
D017931:DNA Primers; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D011518:Proto-Oncogene Proteins; D015500:Chloramphenicol O-Acetyltransferase; D011505:Protein-Tyrosine Kinases; C496645:FES protein, human; D051578:Proto-Oncogene Proteins c-fes