Monoclonal antibodies specific to human ETS-2 oncoprotein: recognition of epitopes clustered on the B domain

Characterization of monoclonal antibodies specific to the transcription factor ETS-2 protein

ETS-2 is a member of the ETS family of transcription factors. ETS-2 was initially characterized as a nuclear oncogene and has been shown to play a role in regulation of apoptosis and cell cycle progression. Members of the ETS family display high sequence homology, thus, there is considerable controversy concerning the specificity of existing ETS-2 polyclonal antibodies that have been used to define ETS-2 function. We therefore embarked on the production of ETS-2 specific monoclonal antibodies. In this report, we describe the production and characterization of six antibodies and the localization of their target epitopes to distinct domains of the ETS-2 protein. Four antibodies are ETS-2 specific and two antibodies cross-react with ETS-1, an ETS family member with the highest amino acid sequence homology to ETS-2. This report provides a comprehensive evaluation of ETS-2 specific monoclonal antibodies verified using ETS-2 null cells. These antibodies can be used for EMSA, Western blotting, immunoprecipitation and immunofluorescence staining experiments. Collectively, these reagents are invaluable molecular tools that should help better understand the biological function of ETS-2.

Ets transcription factors cooperate with Sp1 to activate the human tenascin-C promoter

Tenascin-C (TN-C), an extracellular matrix glycoprotein is expressed during embryonic development, but is present only at low levels in normal adult tissues. TN-C is re-expressed during wound healing, fibrotic diseases and in cancer. To better understand the mechanisms that control TN-C gene expression, we examined the regulation of the human TN-C promoter in human fibroblasts. We demonstrate that a short segment of the TN-C promoter between bp -133 and -27 contains three evolutionarily conserved Ets binding sites (EBS). These three EBSs bind in vitro expressed Fli1 protein and mediate transactivation of the TN-C gene by Fli1. Furthermore, two proximal EBSs contribute significantly to basal activity of the TN-C promoter. GABP, which is present in human fibroblast nuclear extracts, interacts with the two proximal EBSs. In addition, several Sp1 and Sp3 binding sites have been located in close proximity to the EBSs within this promoter region. The studies performed in Drosophila cells demonstrate that either Fli1 or GABPalpha+beta1 functionally interact with Sp1 resulting in a synergistic stimulation of the TN-C promoter activity. In conclusion, this study shows for the first time that the TN-C gene is regulated by Ets proteins, which together with Sp1 act as potent activators of TN-C expression.

Antigenic variation of the Epstein-Barr virus nuclear antigen EBNA1 as revealed by monoclonal antibodies

The Epstein Barr virus (EBV) nuclear antigen EBNA1 plays an essential role in the replication of EBV episomes in latently infected cells and is the only viral protein that is consistently expressed in all programs of latent EBV gene expression. In this study, four monoclonal antibodies (MoAbs) directed to a region (amino acid residues 442-530) of EBNA1 were generated. Competitive enzyme-linked immunosorbent assay (ELISA) experiments using biotinylated MoAbs showed that they recognized distinct epitopes. Reactivity of these MoAbs with various laboratory EBV strains and field EBV isolates was shown to be heterogeneous in that EBNA1 from certain strains (isolates) was recognized and that from others was not. All four MoAbs showed such heterogeneous reactivity, and moreover, each MoAb showed a distinct spectrum of reactivity with these EBV strains (isolates). These results demonstrate an extensive structural variation in this region of EBNA1 as predicted by previous sequencing studies. These MoAbs will be useful as probes to dissect this structural heterogeneity of EBNA1.

Generation and characterization of monoclonal antibodies against the ERGB/FLI-1 transcription factor

Five monoclonal antibodies were produced from mice immunized with recombinant full length human ERGB protein. Among these monoclonal antibodies, four clones did not cross react with other ets family proteins and thus are specific for the ERGB protein; however, one clone did react with the ERG protein, which has high amino acid identity with the ERGB protein. The epitope location of these antibodies was studied using bacterially expressed fragments of the human, ERGB protein. These monoclonal antibodies recognized 51 kDa (p51) and 48 kDa (p48), two ERGB gene-encoded proteins, from human, mouse, and rat cell lines. These results suggest that the monoclonal antibodies can be used in human, mouse, or rat cell lines and will be useful for the biochemical and functional analysis of the ERGB protein.

Optimization of primer sequences for mouse scFv repertoire display library construction

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Characterization and uses of monoclonal antibody derived against DNA binding domain of the ets family of genes

A monoclonal antibody recognizing ets proteins from a variety of species has been developed. This antibody recognizes ets1, ets2, erg, and other related proteins. It has a high affinity for the ets1 protein. The epitope for the pan ets mAb consists of about 13 amino acids. This antibody can be used to isolate and characterize new members of ets gene family derived from a c-DNA expression library, as well as to identify other "ets motif" binding proteins.