Disease relevance of FLII

• Ewing's sarcoma, a highly malignant neoplasm, is characterized by an 11;22 translocation [t(11;22) (q24;q12)], resulting in the fusion of genes FLII and EWS [1].
• In vitro, cells derived from Ewing sarcoma (ES) with the characteristic somatic rearrangement between the genes EWS and FLII can be induced to differentiate toward a neuronal phenotype by exposure to agents such as dibutyryl cyclic AMP (db cAMP) or retinoic acid [2].
• The secondary structure of the ets domain of human Fli-1 resembles that of the helix-turn-helix DNA-binding motif of the Escherichia coli catabolite gene activator protein [3].
• In addition, Fli-1 binding of the GPIX Ets site was identified in antibody supershift experiments in nuclear extracts derived from hematopoietic human erythroleukemia cells [4].
• Therefore, we propose that Ews/Fli-1 contributes to the etiology of ES/PNET by subverting the differentiation program of its neural crest precursor cell to a less differentiated and more proliferative state [5].

High impact information on FLII

• Here we use these fragments to screen human complementary DNA libraries to show that the translocation alters the open reading frame of an expressed gene on chromosome 22 gene by substituting a sequence encoding a putative RNA-binding domain for that of the DNA-binding domain of the human homologue of murine Fli-1 [6].
• T cells express multiple members of the Ets gene family including Ets-1, Ets-2, GABP alpha, Elf-1, and Fli-1 [7].
• Co-transfection experiments in Q2bn fibroblasts showed cooperative activation of the EOS47 proximal promoter by c-Myb, Ets-1/Fli-1, GATA-1 and C/EBPalpha [8].
• The Ets-1/Fli-1 and C/EBPalpha proteins were the most potent activators, and acted with high synergy through juxtaposed binding sites located approximately 60 bp upstream of the transcription start site [8].
• Southern blot analysis of somatic-cell hybrids and/or FISH analysis of lymphoblastoid cell lines from 12 SMS patients demonstrates the deletion of one copy of FLI in all SMS patients analyzed [9].

Biological context of FLII

• We have constructed a transgenic mouse carrying the complete human FLII gene and shown that the FLII transgene is capable of rescuing the embryonic lethality of the homozygous targeted Fliih mutation [10].
• We have cloned the FLII gene and determined its nucleotide sequence (14.1 kb) [11].
• The homologous human FLII gene encodes a 1269-residue protein with 58% amino acid sequence identity and is deleted in Smith-Magenis syndrome [11].
• FLII has 29 introns, compared with 13 in Caenorhabditis elegans and 3 in D. melanogaster [11].
• The FLII gene lies adjacent to LLGL, the human homologue of the D. melanogaster tumor suppressor gene lethal(2) giant larvae [11].

Anatomical context of FLII

• Skeletal and cardiac muscles are particularly rich in the 3.3-kb FLAP message, and the FLI message as well [12].
• FLI has a C-terminal gelsolin-like domain which binds actin and therefore the association of TRIP with the FLI LRR may provide a link between the actin cytoskeleton and RNA in mammalian cells [13].
• MATERIALS AND METHODS: RT-PCR assays for the EWS-FLII, EWS-ERG, PAX3-FKHR, PAX7-FKHR, and EWS-WTI fusion transcripts were performed on RNA extracted from the primary tumor tissue, bone marrow, and body fluids obtained at initial presentation and relapse [14].
• In addition, expression of Fli-1 was identified immunohistochemically in megakaryocytes derived from CD34(+) cells treated with the megakaryocyte differentiation and proliferation factor, thrombopoietin [4].
• To test the effect on endogenous genes, we stably overexpressed Fli-1 in K562 cells, a line rich in GATA-1 [15].

Associations of FLII with chemical compounds

• CONCLUSIONS: Molecular detection of EWS-Fli1 fusion transcripts in formalin-fixed paraffin-embedded material by nested RT-PCR is feasible and is useful for the diagnosis and differential diagnosis of ES/pPNETs [16].
• Regulation of the megakaryocytic glycoprotein IX promoter by the oncogenic Ets transcription factor Fli-1 [4].
• These reciprocal functional interactions extended to other nuclear receptors such as thyroid hormone and retinoic acid receptors, as well as to Fli1, an ERG-related ETS factor [17].
• In this report, we show that the recombinant Fli-1 protein expressed in bacteria binds to DNA in a sequence-specific manner [18].
• Functional interference between retinoic acid or steroid hormone receptors and the oncoprotein Fli-1 [19].

Physical interactions of FLII

• We map the minimal domains required for the interaction and show that the zinc fingers of GATA-1 interact with the Ets domain of Fli-1 [15].
• The ets family member Tel binds to the Fli-1 oncoprotein and inhibits its transcriptional activity [20].
• Furthermore, Fli-1 binding to the COL1A2 is enhanced via Sp1-dependent interaction [21].
• In the majority of Ewing's family tumors, chromosomal translocation t(11;22) leads to aberrant fusion of RNA-binding protein EWS with DNA-binding ETS transcriptional factor Fli-1 [22].

Regulatory relationships of FLII

• We propose that Fli-1 inhibits COL1A2 promoter activity by competition with Ets-1 [21].
• Our studies showed that PKD1 promoter-luciferase reporter gene expression is downregulated by cotransfected Fli-1 and is upregulated by cotransfected Ets-1 [23].
• Overexpression of Fli-1 inhibits the retinoic acid-induced activation of genes carrying a functional retinoic acid response element (RARE) [19].

Other interactions of FLII

• We report the identification of two related genes, LRRFIP1 and LRRFIP2, encoding proteins that interact with the LRR domain of human FLI using the yeast two-hybrid system [24].
• We present two patients with SMS who have interstitial deletions at 17p11.2 but are not deleted for currently available commercial FISH probes that include FLII; both patients have deletions that are demonstrated with probes containing the RAI1 gene [25].
• Fli-1 and CD99 were detected in 90% and 55% of cases, respectively [26].
• The involvement of the ET-specific fusion transcript EWS/Fli-1 in modulating the HLA-A and -B locus antigens is likely to occur by the upregulation of c-myc in these tumors [27].
• Here we report the physical interaction of Fli-1 with GATA-1, a well-characterized, zinc finger transcription factor critical for both erythroid and megakaryocytic differentiation [15].

Analytical, diagnostic and therapeutic context of FLII

• Binding to FLI LRR was corroborated by co-immunoprecipitation with FLI LRR [12].
• Overexpression of Fli-1 induced the expression of the endogenous GPIX and GPIbalpha genes as measured by Northern blot and fluorescence-activated cell sorter analysis [15].
• Sequence analysis revealed two domains of ets homology, one at the 5' and the other at the 3' end of the Fli-1 gene [28].
• Immunofluorescence revealed that in the neuroblastoma-Ews/Fli-1 infectant cell lines, p53 went from a punctate-pattern of cytoplasmic sequestration to increased nuclear localization [29].
• Herein, we utilize chromatin immunoprecipitation to examine the presence of Ets-1, Fli-1, and GATA-1 on these promoters in vivo [30].

References