Fli-1b is generated by usage of differential splicing and alternative promoter

Oncogene. 1998 Sep 3;17(9):1149-57. doi: 10.1038/sj.onc.1202030.

Abstract

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.

Publication types

  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Alternative Splicing / genetics*
  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Binding Sites / genetics
  • Chloramphenicol O-Acetyltransferase / genetics
  • DNA, Complementary / chemistry
  • DNA, Complementary / genetics
  • DNA, Complementary / isolation & purification
  • DNA-Binding Proteins / genetics*
  • DNA-Binding Proteins / physiology
  • Gene Expression / genetics
  • Humans
  • Molecular Sequence Data
  • Promoter Regions, Genetic / genetics
  • Proto-Oncogene Protein c-fli-1
  • Proto-Oncogene Proteins*
  • RNA, Messenger / analysis
  • RNA, Messenger / genetics
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Sensitivity and Specificity
  • Sequence Analysis, DNA
  • Sequence Deletion / genetics
  • Sequence Homology, Nucleic Acid
  • TATA Box / genetics
  • Trans-Activators / genetics*
  • Trans-Activators / physiology
  • Transcription, Genetic / genetics
  • Transfection
  • Tumor Cells, Cultured / cytology
  • Tumor Cells, Cultured / metabolism

Substances

  • DNA, Complementary
  • DNA-Binding Proteins
  • Proto-Oncogene Protein c-fli-1
  • Proto-Oncogene Proteins
  • RNA, Messenger
  • Recombinant Fusion Proteins
  • Trans-Activators
  • Chloramphenicol O-Acetyltransferase