Negative and positive regulation by a short segment in the 5'-flanking region of the human cytomegalovirus major immediate-early gene.

Ets-2 Repressor Factor (ERF) mediates repression of the human cytomegalovirus major immediate-early promoter in undifferentiated non-permissive cells

“…For example, there are numerous nuclear factor-1 (NF-1) sites within the MIEP and the 18 and 19 bp repeat sequences contain NF-kB and cyclic AMPresponsive element binding protein (CREB) binding sites respectively (Meier & Stinski, 1996). Conversely, several studies using non-permissive cells have shown that the modulator and the 21 bp repeats are responsible for the inhibition of MIEP activity in such cells (Nelson et al, 1987;Lubon et al, 1989;Kothari et al, 1991).…”

“…For example, there are numerous nuclear factor-1 (NF-1) sites within the MIEP and the 18 and 19 bp repeat sequences contain NF-kB and cyclic AMPresponsive element binding protein (CREB) binding sites respectively (Meier & Stinski, 1996). Conversely, several studies using non-permissive cells have shown that the modulator and the 21 bp repeats are responsible for the inhibition of MIEP activity in such cells (Nelson et al, 1987;Lubon et al, 1989;Kothari et al, 1991).In vivo, monocytes have been identified as an important site of HCMV latency (Taylor-Wiedeman et al, 1991); these cells carry the viral genome in the absence of lytic (productive) gene expression. Experiments in our laboratory and those of others have shown that the differentiation of peripheral blood monocytes to macrophages (monocytederived macrophages; MDMs) results in the induction of endogenous HCMV IE gene expression and reactivation of virus (Taylor-Wiedeman et al, 1994;Soderberg-Naucler et al, 1997).…”

Strong conservation of the constitutive activity of the IE1/2 transcriptional control region in wild-type strains of human cytomegalovirus.

“…1) ; the upstream primer bound at position k1974, thereby including the so-called modulator upstream of the enhancer and promoter region. Several published reports indicate that the modulator element can repress the transcriptional activity of the IE1\2 enhancer\ promoter in a cell type-dependent manner when investigated by transient transfection or by in vitro transcription experiments Lubon et al, 1989 ;Nelson et al, 1987 ;Shelbourn et al, 1989). The downstream primer bound at position j966, within exon 2 of the IE1\2 gene.…”

“…Human teratocarcinoma cell lines have been shown to be particularly sensitive to deletions within the region upstream of the IE1\2 enhancer (Lubon et al, 1989 ;Nelson et al, 1987 ;Shelbourn et al, 1989). Since we wanted to determine whether the variations detected could influence expression levels in these cells, additional transfection experiments were performed using Tera-2 and NT-2\D1 cells together with constructs containing the IE1\2 transcriptional control regions of strains 1, 2, 4, 5 and the reference strain AD169 (Fig.…”

“…Surprisingly, whereas the so-called unique region containing binding sites for nuclear factor NF-1 showed slightly higher sequence variability, the strict nucleotide sequence conservation of the enhancer was also observed in the upstream modulator region. Although several studies have demonstrated a modulatory influence of this cis-acting element in transient expression analyses and in vitro transcription experiments, deletion of the modulator from the HCMV genome did not affect transcription from the IE1\2 gene region appreciably after infection of several cell types (Lubon et al, 1989 ;Nelson et al, 1987 ;Sinclair et al, 1992 ;Shelbourn et al, 1989 ;Liu et al, 1994 ;Meier & Stinski, 1997). It has also been reported that a hypothetical ORF UL127 spans the modulator region, possibly contributing to the function of this region (Meier & Stinski, 1997).…”