Fli-1b is generated by usage of differential splicing and alternative promoter.
The proto-oncogene Fli-1, a member of Ets family is rearranged or activated through proviral integration in erythroleukemias, induced by Friends' Murine Leukemia Virus. The DNA binding domain (ETS domain) of Fli-1 is fused to the RNA binding domain of EWS by t(11q24:22q12) chromosomal translocation in Ewing's sarcoma and primitive neuroectodermal tumors. Screening of human cDNA libraries has identified two different 5'-termini and alternatively spliced forms of the human Fli-1 gene (Fli-1b), suggesting the possible existence of two independent promoters. The genomic sequence adjacent to the alternate exon of human Fli-1b gene shows functional promoter activity when cloned in promoter-less CAT expression vector and transfected into QT-6 cells. The transcription initiation (CAP) site and minimum promoter region necessary for function were localized. The 5'-flanking regions of human Fli-1b and mouse Fli-1 show 80% homology suggesting conserved promoter regulatory elements. The Fli-1b 5'-flanking sequence lacks canonical TATA or CCAAT boxes but contains a partially conserved TATA-like sequence at position 242. Several transcription factor binding sequences like ATF/CREB, E2A-PBX1, EBP, PEA-3, ETS-2, Sp-1, c-Myc, TBP, GATA-1 and Oct-3 were conserved in the promoter sequence. Functional promoter assays revealed that Fli-1b promoter shows very strong transcriptional activation compared to Fli-1 promoter. We also showed that variant Fli-1b has transcriptional activation properties similar to those of Fli-1. Fli-1b and Fli-1 show differential expression in various hematopoietic cell lines. This differential expression and promoter activities of Fli-1 and Fli-1b suggests that several mechanisms are involved in Fli-1 gene regulation which are mediated by many transcription factors.
Dhulipala
P D
PD
Department of Human Genetics, Allegheny University of the Health Sciences, Philadelphia, Pennsylvania 19102, USA.
Lee
L
L
Rao
V N
VN
Reddy
E S
ES
D017398:Alternative Splicing / Q000235:genetics*; D000595:Amino Acid Sequence; D000818:Animals; D001483:Base Sequence; D001665:Binding Sites / Q000235:genetics; D015500:Chloramphenicol O-Acetyltransferase / Q000235:genetics; D018076:DNA, Complementary / Q000737:chemistry / Q000235:genetics / Q000302:isolation & purification; D004268:DNA-Binding Proteins / Q000235:genetics* / Q000502:physiology; D015870:Gene Expression / Q000235:genetics; D006801:Humans; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic / Q000235:genetics; D000090063:Proto-Oncogene Mas; D051789:Proto-Oncogene Protein c-fli-1; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger / Q000032:analysis / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D012680:Sensitivity and Specificity; D017422:Sequence Analysis, DNA; D017384:Sequence Deletion / Q000235:genetics; D012689:Sequence Homology, Nucleic Acid; D016385:TATA Box / Q000235:genetics; D015534:Trans-Activators / Q000235:genetics* / Q000502:physiology; D014158:Transcription, Genetic / Q000235:genetics; D014162:Transfection; D014407:Tumor Cells, Cultured / Q000166:cytology / Q000378:metabolism
D018076:DNA, Complementary; D004268:DNA-Binding Proteins; C000715470:MAS1 protein, human; D000090063:Proto-Oncogene Mas; D051789:Proto-Oncogene Protein c-fli-1; D011518:Proto-Oncogene Proteins; D012333:RNA, Messenger; D011993:Recombinant Fusion Proteins; D015534:Trans-Activators; D015500:Chloramphenicol O-Acetyltransferase