The proto-oncogene c-ets is preferentially expressed in lymphoid cells.

Abstract

The transforming sequences of the avian acute leukemia virus, E26, contain two distinct oncogenes, v-mybE and v-ets, fused together. By using a probe containing v-ets sequences, polyadenylated transcripts of the c-ets proto-oncogene were detected in avian tissues; they included a major 7.0-kilobase and a minor 2.0-kilobase species. These c-ets mRNAs were detected at high levels only in lymphoid organs and in avian T and B lymphoid cell lines. A similar pattern of c-ets transcription was observed in human hematopoietic cell lines, with transcripts detected in lymphoid B and T cells but not in erythroid or myeloid cells. The E26 oncogene was inserted into an inducible expression vector, and a 90-kilodalton protein (bp9O) was produced in bacteria. Rabbit antisera raised to purified bp9O precipitated p135gamYybEets, the v-mybE-ets polyprotein expressed in E26-transformed cells, and also reacted with p50vmsbA, the transforming protein of the avian myeloblastosis virus. Antiserum to bp9O was absorbed with a bacterially synthesized v-mybA protein to remove anti-myb activity. The absorbed anti-bp9O serum retained the ability to immunoprecipitate p135gag9-YbetS from E26-transformed cells and specifically reacted with a 56-kilodalton polypeptide (p56) detected in chicken lymphoid organs and in T and B lymphocytes of both avian and human origin. The data suggest that p56 is a translational product of the c-ets proto-oncogene and imply that p56 may be involved in regulating the growth of lymphoid cells.

A thymus-specific member of the HMG protein family regulates the human T cell receptor C alpha enhancer.

“…Although these data suggest that TCF-2a is identical to c-ets-1, several observations indicate that recognition of the TCF-2e~ site is more complex. First, TCF-2e~-binding activity appears to be restricted to T cells, whereas c-ets-1 is abundant in B cells and macrophages, as well as T cells (Chen 1985;Bhat et al 1989). In addition, Southwestern experiments indicate that TCF-2~ is a 63-kD protein (M.L.…”

Expression and function of Ets transcription factors in mammalian development: a regulatory network

“…However, as these cells mature, Erg expression is markedly reduced (Figure 1). The downregulation of Erg during T-cell di erentiation may be necessary for maturation (Barton et al, 1998), as is observed for Ets1 in T cell activation (Bhat et al, 1990;Bories et al, 1995;Chen, 1985;Muthusamy et al, 1995). Expression of Erg during embryonic development of the vascular tree progressively decreases with endothelial maturation.…”

“…Preferential expression of Ets1 occurs in B, T and NK cells of adult mice, with high levels in the CD3+ subclass of peripheral T cells (Figure 1) (Barton et al, 1998;Bassuk and Leiden, 1997;Bhat et al, 1989;Chen, 1985). Ets1 is not required for the development of B and T cell lineages, but appears to be essential for their survival and maturation (Bories et al, 1995;Muthusamy et al, 1995).…”

“…Regulation of the Ets1 gene occurs at both the transcriptional and posttranslational levels during T-cell activation (Bhat et al, 1989;Pognonec et al, 1988). Ets1 is highly expressed in quiescent mature T cells and is critical to the maintenance of T cells in the G0 phase of the cell cycle (Bhat et al, 1990;Bories et al, 1995;Chen, 1985;Muthusamy et al, 1995). Following T-cell activation, a transcriptionally active form of Ets1 is inactivated (Pognonec et al, 1988;Bhat et al, 1990;Rabault and Ghysdael, 1994).…”

Sequence-specific DNA binding of the proto-oncoprotein ets-1 defines a transcriptional activator sequence within the long terminal repeat of the Moloney murine sarcoma virus.

“…These data suggest that a protein with the DNA-binding activity of ets-1 functions as a transcriptional activator. It is reasonable to propose that ets-1 is the EL4 cell protein that functions as an activator of the LTR-mediated expression, since RNA and protein products of the mammalian and chicken ets-1 genes have been reported to be expressed preferentially in lymphoid cells (Chen 1985;Ghysdael et al 1986;Bhat et al 1987Bhat et al , 1989, including mouse EL4 cells. However, if the DNA-binding domain of ets-1 is encoded by the highly conserved region of the ets gene family (as hypothesized above), the data cannot eliminate other ets family members as possible transcriptional activators in EL4 cells.…”