Human c‐myc gene contains a regulatory site similar to consensus of interferon response sequence (IRS)

Abstract

Expression of c‐myc proto oncogene is regulated by multiple mechanisms. Here, we report that the consensus of the regulatory region of interferondependent genes, GGAAAN1−3 GAAA, was found after computer search in the 5'‐terminal flank of human c‐myc gene in position (−76:−67). In vitro transcription of c‐myc gene fragments showed that the consensus region competes with oligonucleotide GGGAAAATGAAACT for binding to specific protein(s). This oligonucleotide was shown to bind selectively the interferon‐dependent positive transcription factor [1]. Transcription of c‐myc fragments lacking 5'‐terminal region up to positions −101 or +71 was initiated at two sites located in the first intron. These sites did not coincide with P1 in vivo RNA cap‐site. Binding of the protein factor(s) to the regulatory region of c‐myc gene −76:−67 blocked the in vitro transcription initiated in the first intron.

c‐Raf kinase binds to N‐terminal domain of c‐Myc

“…2B) as previously described [16]. Mostly Thr and much smaller amount of Ser appeared to be phosphorylated.…”

“…Phosphoamino acid analysis was performed as described earlier [16] with slight modifications. Fusion protein on beads was phosphorylated in vitro with CEM cell lysate as a source of kinase activity as described above, and cleaved with thrombin according to the pro- cedure described in [17].…”

Binding of proteins of HeLa S3 cell extract to oligonucleotides containing the consensus interferon‐response sequence (IRS) and to the IRS‐containing fragment of the human c‐myc gene

“…In the comprehensive presentation by Porter et al [8], it was shown that GGGAAAATGAAACT oligonucleotide competes with the IRS region of the human 6-16 gene, but GGGAAAATGACACT (i. e. the oligonucleotide with one mismatch) does not. The competition was analyzed by a gelretardation technique: the data have shown a high level of specificity of factors binding to the IRS sequence.Recently we proposed the IRS consensus sequence to be as follows : GGAAAN -,GAAA [13]. This consensus differs from analogous sequences that were described previously (see above), which is why the computer search for this consensus showed the presence of corresponding regions in the regula- tory parts of genes that were not characterized earlier as IFNdependent.…”

“…This consensus differs from analogous sequences that were described previously (see above), which is why the computer search for this consensus showed the presence of corresponding regions in the regula- tory parts of genes that were not characterized earlier as IFNdependent. This group of genes includes the human protooncogene c-myc [13].The IRS consensus sequence in the human c-myc gene was located at position -76 to -67 (+ 1 indicates P i cap site): c-myc: GGAAA A GAAA consensus: GGAAA N 1 -3GAAA.Previously we have shown that regulatory protein(s) present in a HeLa S3 cell extract which binds to the IRS region of the human IFN-dependent 6-16 gene can also bind to the IRS of c-myc [13]. Here, we have demonstrated that HeLa S3 nuclear extract contains different protein factors, at least two, that bind preferentially to the IRS sequence of either the cmyc or the 6-16 gene.…”

“…This consensus differs from analogous sequences that were described previously (see above), which is why the computer search for this consensus showed the presence of corresponding regions in the regula- tory parts of genes that were not characterized earlier as IFNdependent. This group of genes includes the human protooncogene c-myc [13].…”