Cloning, sequencing, and expression of two Xenopus laevis c-ets-2 protooncogenes

Abstract

In a general approach to identify genes important in the control of genetic expression during development of Xenopus laevis, two complementary DNAs corresponding to two different c-ets-2 genes were cloned and sequenced. One of these complementary DNAs appears to be almost full length. The two variant genes differ in their overlapping sequences by 87 nucleotide substitutions, leading to 17 amino acid modifications in the proteins, 8 of them being conservative. All but one of these changes map outside of the 142 COOH-terminal residues, a region critical for nuclear localization and DNA binding in the ets proteins. Features potentially important for the biological activity of the gene products are conserved. Two transcripts (3.2 and 1.7 kilobases) with maternal characteristics are detected at a constant level from stages II/III of oogenesis to stage 10 of embryogenesis. They later decline to hardly detectable levels at stages 30-40. Variable amounts of the same transcripts are observed in many adult tissues. All of these characteristics support the idea that the ets-2 gene products play an important role during embryogenesis, as well as in adult life. Indeed, they act as ubiquitous transcriptional activators, as recently demonstrated by several investigators (C. V. Gunther, J. A. Nye, R. S. Bryner, and B. J. Graves, Genes & Dev., 4: 667-679, 1990; R. Bosselut, J.F. Duvall, A. Gegonne, M. Bailly, A. Hemar, J. Brady, and J. Ghysdael, EMBO J., 9: 3137-3144, 1990; R. Wasylyk, C. Wasylyk, P. Florès, A. Bègue, D. Leprince, and D. Stéhelin, Nature (Lond.), 346: 191-193, 1990).