Chromatin from transcribed genes contains HMG17 only downstream from the starting point of transcription.

Dorbic, Tomislav; Wittig, Burghardt

doi:10.1002/j.1460-2075.1987.tb02517.x

Cited by 70 publications

(31 citation statements)

References 27 publications

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“…Early work with nucleosomal core particles had suggested that HMG14/17 interact preferentially with chromatin of actively transcribed genes (for review, see Weisbrod 1982}, but technical limitations of those experiments, which include the rapid exchange of HMG14/17 in vitro {Landsman et al 1986) and variability in the binding of HMG14/17 to core particles (Swerdlow and Varshavsky 1983), had also led to some disagreement regarding the results. In other studies, an enrichment of HMG14/17 in active chromatin was observed by protein-DNA cross-linking (--1.5-to 2.4-fold enrichment; Postnikov et al 1991 ) as well as by immunoffactionation of oligonucleosomes with a monoclonal antibody against HMG17 (-~60-to 100-fold enrichment; Dorbic and Wittig 1987). These experiments did not, however, distinguish whether the enrichment of HMG17 had augmented gene activity or was a consequence of transcription.…”

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confidence: 79%

HMG17 is a chromatin-specific transcriptional coactivator that increases the efficiency of transcription initiation.

Paranjape¹,

Krumm²,

Kadonaga³

1995

Genes Dev.

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We have examined the effect of HMG17 on transcription by RNA polymerase II by the assembly and analysis of HMG17-containing chromatin templates consisting of regularly spaced nucleosomal arrays. Structural analysis of the chromatin indicated that HMG17 is incorporated into chromatin in a physiological manner with the full complement of core histones. The transcriptional studies revealed that HMG17 stimulates transcription in conjunction with the sequence-specific activator GAL4-VP16. This effect was observed with chromatin, but not with non-nucleosomal templates, and required the presence of HMG17 during chromatin assembly. The incorporation of HMG17 into chromatin resulted in a 7-to 40-fold stimulation of GAL4-VP16-activated transcription to levels that were comparable to those observed with histone-free DNA templates. In contrast, transcription from HMG17-containing chromatin was not detectable in the absence of GAL4--VP16 or with a GAL4 derivative [GAL4(1-147)] lacking the VP16 activation domain. Finally, the incorporation of HMG17 into chromatin was found to increase the efficiency of transcription initiation, but not the extent of transcriptional elongation. Thus, HMG17 is a chromatin-specific transcriptional coactivator that increases the efficiency of initiation of transcription by RNA polymerase II.

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mentioning

confidence: 79%

HMG17 is a chromatin-specific transcriptional coactivator that increases the efficiency of transcription initiation.

Paranjape¹,

Krumm²,

Kadonaga³

1995

Genes Dev.

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“…Reverse transcriptase reactions were carried out using Multiscribe reverse transcriptase (Applied Biosystems) and oligo(dT) 16 according to the manufacturer's instructions. An aliquot of the cDNA was used in real-time PCR, using SYBR green (Applied Biosystems) in an ABI PRISM 7900HT sequence detection system according to the manufacturer's instructions.…”

Section: Methodsmentioning

confidence: 99%

“…Immunofluorescence studies have shown that HMGN proteins are localized in many foci within the nucleus and that the foci contain either HMGN1 or HMGN2 (38). They have a slight preference for binding to transcriptionally active genes (16,17,20,39), and it has also been shown that they tend to bind in clusters on arrays of approximately six contiguous nucleosomes (38). However, the organization of HMGN proteins is highly dynamic in live cells, and their association with any specific nucleosome is temporary (37).…”

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confidence: 99%

Chromosomal Proteins HMGN3a and HMGN3b Regulate the Expression of Glycine Transporter 1

West

Castellini

Duncan

et al. 2004

Molecular and Cellular Biology

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HMGN proteins promote chromatin unfolding, enhance access to nucleosomes, and modulate transcription from chromatin templates. It is not known whether they act indiscriminately as general modulators of transcription or whether they regulate specific gene expression. Here, we investigated the role of HMGN3, a recently discovered HMGN family member, in transcription in vivo. We created cell lines overexpressing HMGN3a or its splice variant, HMGN3b, and analyzed their gene expression profiles using microarrays and reverse transcriptase PCR. We found that ectopic expression of HMGN3a alters the expression of approximately 0.8% of genes. Both HMGN3a and HMGN3b upregulate the expression of the glycine transporter 1 gene (Glyt1). Glyt1 encodes a membrane transporter that regulates the glycine concentration in synaptic junctions. Both GLYT1 and HMGN3 are highly expressed in glia cells and the eye, and we show that both proteins are coexpressed in the retina. Chromatin immunoprecipitation assays showed that HMGN3 protein is recruited to a region of the Glyt1 gene encompassing the Glyt1a transcriptional start site. These results suggest that HMGN3 regulates Glyt1 expression and demonstrate that members of the HMGN family can regulate the transcription of specific genes.In eukaryotes, all of the DNA is complexed with histone proteins and packaged into a highly folded, well-ordered, and dynamic structure called chromatin. This packaging modulates the ability of regulatory factors to access their DNA targets and plays a major role in regulating various nuclear activities, including transcription (18,48). Chromatin folding is modulated by numerous nuclear factors including nucleosome remodeling complexes, histone-modifying enzymes, and architectural proteins such as linker histones and HMG proteins. Members of the HMG superfamily interact with chromatin and DNA and affect a wide range of DNA-dependent activities such as transcription, replication, and recombination (9).One of the HMG families, the HMGN family, is comprised of small, basic proteins that bind specifically to nucleosomes (8). HMGN proteins are highly conserved and found only in vertebrates. The two founding members of the family, HMGN1 and HMGN2 (formerly named HMG-14 and HMG-17) (8), have been studied extensively. They contain a highly conserved nucleosome binding domain, a bipartite nuclear localization signal, and a C-terminal chromatin-unfolding domain (12, 47). When incorporated into minichromosomes, HMGN proteins confer a more open chromatin structure that is more sensitive to nucleases and that is transcribed and replicated more efficiently (13,14,35,46,50). Their ability to unfold chromatin also enhances the rate of DNA repair, as recently demonstrated in mice lacking HMGN1 (5).Although HMGN proteins display little or no DNA sequence specificity when binding to nucleosomes (45), several lines of evidence indicate that HMGN binding within the nucleus is nonrandom. Immunofluorescence studies have shown that HMGN proteins are localized in many foci within t...

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“…When oviduct and liver are compared as expressing and nonexpressing tissues (21)(22)(23), one obtains the generally accepted indirect correlation between methylation and gene expression-i.e., methylated CpG residues indicate the inactive state (liver), and unmethylated CpGs indicate the active state (oviduct). When macrophages and erythrocytes are compared as hormone-insensitive tissues having an active and inactive lysozyme locus, respectively (10), the gene is seen to be undermethylated in both expression states.…”

Section: Discussionmentioning

confidence: 99%

Lack of correlation between DNA methylation and transcriptional inactivation: the chicken lysozyme gene.

Wölfl

Schräder²,

Wittig³

1991

Proc. Natl. Acad. Sci. U.S.A.

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We have analyzed the methylation state of all nine CpG sites in the Otrascription start region (-420 to +250 base pairs) of the chicken lysozyme gene by genomic sequencing. One of these sites, at -81, lies within the promoter, seven are clustered within the first exon, and the last is in the first intron. Five cell types and tissues have been investigated to study the relationship between methylation level and gene expression. For each cell type used, the majority of CpG sites showed a similar level of methylation. Of two genenonexpressing tissues, erythrocytes are hypomethylated, whereas liver is methylated at most of its CpG sites. For gene-expressing tissues, oviduct is completely unmethylated, whereas HD-1l culture cells are methylated. Thus no correlation is observed between degree of CpG methylation and level of expression of the lysozyme gene. The observed methylation patterns are discussed in terms of possible features of the local chromatin structure.

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Chromatin from transcribed genes contains HMG17 only downstream from the starting point of transcription.

Cited by 70 publications

References 27 publications

HMG17 is a chromatin-specific transcriptional coactivator that increases the efficiency of transcription initiation.

HMG17 is a chromatin-specific transcriptional coactivator that increases the efficiency of transcription initiation.

Chromosomal Proteins HMGN3a and HMGN3b Regulate the Expression of Glycine Transporter 1

Lack of correlation between DNA methylation and transcriptional inactivation: the chicken lysozyme gene.

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