Developmental regulation of specific protein interactions with an enhancerlike binding site far upstream from the avian very-low-density apolipoprotein II gene.

Hoodless, Pamela A.; Roy, Rabindra; Ryan, Aimee K.; Haché, Robert J.G.; Vasa, Monika; Deeley, Roger G.

doi:10.1128/mcb.10.1.154

Cited by 10 publications

(10 citation statements)

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“…After the chicks hatched, the levels of the mRNA in the liver decreased a further three-to fivefold until they reached the levels found in adult roosters. This pattern of expression was similar to that of the site 1 binding activity, as measured previously by gel retardation assay (31). To address the possibility that the levels of mRNA and active protein may 48 h or 2 weeks after treatment.…”

Section: Resultsmentioning

confidence: 94%

“…These studies have generated alternative suggestions that YB-1 binds to damaged DNA (30,43) or single-stranded CT-rich DNA (38) or that it is an RNA binding protein (15,49). The oligonucleotide we have used has a number of enhancer-like structural characteristics, but it does not contain a CCAAT box in either orientation (31). The site does contain several copies of the sequence CCA on both strands and a single reverse CCAA motif (Table 1).…”

Section: Resultsmentioning

confidence: 99%

“…Earlier studies of site 1 demonstrated that it competed effectively with sites to which the liver-enriched factor C/EBP was known to bind, although reciprocal competition was not observed (31). Consequently, we examined the ability of chkYB-1 to bind to an oligonucleotide corresponding to a sequence optimized for binding to C/EBP and containing a reverse CCAAT sequence (39).…”

Section: Resultsmentioning

confidence: 99%

“…Acquisition of this ability coincides with demethylation of an MspI site located 2.6 kb upstream from the major transcriptional initiation site of the apoVLDLII gene. The MspI recognition sequence has been shown to be part of a protein binding site containing two enhancer core sequences (11,31). Gel observations raised the possibility that different proteins may interact with the site in embryonic and adult liver or that the proteins involved may be modified during embryogenesis.…”

mentioning

confidence: 99%

“…We have referred to the protein as chkYB-1, rather than EFla, to be consistent with nomenclature used for other species. The oligonucleotide used for screening corresponded to a protein binding site in the 5'-flanking region of the estrogendependent very-low-density apolipoprotein II (apoVLDLII) gene, which, as we have shown previously, undergoes developmentally programmed demethylation (31).…”

mentioning

confidence: 99%

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Cloning and characterization of chicken YB-1: regulation of expression in the liver.

Grant¹,

Deeley²

1993

Mol. Cell. Biol.

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A cDNA expression library constructed from day 9 embryonic liver was screened with a previously identified protein binding site in the flanking region of the liver-specific, estrogen-dependent avian apoVLDLII gene. Two of the clones isolated were shown to encode the chicken homolog of the Y-box binding protein, YB-1 (dbpb), which we have designated chkYB-1. This protein was originally identified in avian extracts by virtue of its ability to bind to two reverse CCAAT motifs in the Rous sarcoma virus enhancer. Since its identification, additional nucleic acid binding properties have been ascribed to its homologs, or closely related proteins, in other species. We have determined the sequence of chkYB-1, investigated its ability to bind to sites known to be involved in tissue-specific expression in the liver, and examined factors influencing its hepatic expression. These studies have demonstrated that the level of chkYB-1 mRNA in the liver decreases steadily throughout embryogenesis and for several weeks posthatching until adult levels are attained. We present several lines of evidence that YB-1 expression in the liver is positively associated with DNA synthesis or cell proliferation. Its binding characteristics indicate that the protein can interact specifically with a number of binding sites for liver!-enriched or specific factors. In addition, although it is not particularly asymmetric in terms of base composition, we find a marked preference in binding to the pyrimidine-rich strand of these sites regardless of the presence or polarity of an intact CCAAT box. The increased levels of expression of YB-1 during proliferation combined with its binding characteristics suggest that it may be involved in the reduced expression of liver-specific genes observed at early stages of development or during liver regeneration.A large number of elements involved in the regulation of eukaryotic genes contain a variation of the motif CCAAT as a subsequence (33). Sites containing such motifs have been shown to be recognized by a number of different trans-acting factors, some of which display restricted tissue distribution and others of which are ubiquitous (2, 44). A requirement for sequences in addition to the CCAAT motif has been demonstrated for some factors, but others display an ability to bind an array of sites with apparently little structural similarity other than the motif itself (9,18,19,29,39,61). A particularly striking example of the latter group is provided by the avian factor EFla, which was initially identified in crude nuclear protein extracts by virtue of its ability to bind to a site in the Rous sarcoma virus (RSV) long terminal repeat (LTR) (21,29,51,62). This protein has been purified and shown to bind to sites in the RSV LTR either as a homodimer or as a heterodimer formed with a second protein designated EFlb. Subsequently, EFla was shown to be capable of interacting with a number of binding sites for trans-acting factors that contain the sequence CCAAT in the noncoding DNA strand.DNA binding proteins that ha...

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Section: Resultsmentioning

confidence: 94%