Linker histones versus HMG1/2: a struggle for dominance?

Zlatanova, Jordanka; Holde, Kensal van

doi:10.1002/(sici)1521-1878(199807)20:7<584::aid-bies10>3.0.co;2-w

Cited by 54 publications

(22 citation statements)

References 51 publications

(48 reference statements)

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“…Several in vitro studies have suggested that competition with nuclear proteins, mainly HMG proteins, might affect the binding of H1 to chromatin (12,29,43,64). Our studies indicate that such a competition occurs in living cells.…”

Section: Discussionmentioning

confidence: 99%

“…These non-histones decompact the higher-order chromatin structure and promote the binding of nuclear regulatory factors (1,12,49,58). Footprinting analysis and in vitro binding assays (29,64) showed that the chromatin binding sites of the HMG proteins are similar to those of H1 and suggested that HMG proteins and H1 compete for the same binding sites, and recent photobleaching experiments demonstrated that HMGN proteins affect the binding of H1 to chromatin in living cells (16). Photobleaching techniques like fluorescence recovery after photobleaching (FRAP), which is used to monitor the intracellular mobility of molecules in living cells, revealed that the interaction of chromatin binding proteins with their nuclear targets is temporary and that these proteins constantly move throughout the entire nucleus (45).…”

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confidence: 99%

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Network of Dynamic Interactions between Histone H1 and High-Mobility-Group Proteins in Chromatin

Catez

Yang

Tracey

et al. 2004

Molecular and Cellular Biology

246

262

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Histone H1 and the high-mobility group (HMG) proteins are chromatin binding proteins that regulate gene expression by modulating the compactness of the chromatin fiber and affecting the ability of regulatory factors to access their nucleosomal targets. Histone H1 stabilizes the higher-order chromatin structure and decreases nucleosomal access, while the HMG proteins decrease the compactness of the chromatin fiber and enhance the accessibility of chromatin targets to regulatory factors. Here we show that in living cells, each of the three families of HMG proteins weakens the binding of H1 to nucleosomes by dynamically competing for chromatin binding sites. The HMG families weaken H1 binding synergistically and do not compete among each other, suggesting that they affect distinct H1 binding sites. We suggest that a network of dynamic and competitive interactions involving HMG proteins and H1, and perhaps other structural proteins, constantly modulates nucleosome accessibility and the local structure of the chromatin fiber.The chromatin fiber is a dynamic, malleable structure that is targeted by numerous regulatory factors that modify the histones and the DNA and remodel the structure of the nucleosome. The dynamics of the chromatin fiber reflect the combined action of numerous chromatin modifiers, including architectural proteins such as histone H1 and members of the high-mobility group (HMG) protein superfamily. The interaction of histone H1 with nucleosomes stabilizes the higherorder, compact chromatin structure (57, 61), thereby restricting the ability of regulatory factors, nucleosome remodeling complexes, and histone modifiers to access their chromatin binding sites (17,27,28,30,32,34). Loss of H1 results in both up regulation and down regulation of specific gene expression (2,26,53,56), suggesting that the protein affects the action of both positive and negative transcriptional regulators. Experiments with H1 knockout mice demonstrate the existence of cellular mechanisms that strive to maintain a constant level of H1 and that reduction of H1 beyond a critical point is not compatible with normal embryonic development (21). Thus, factors that modulate the interaction of H1 with nucleosomes may affect a variety of chromatin-related processes and participate in genetic regulatory mechanisms.The HMG superfamily is composed of three families: HMGB, HMGA, and HMGN, each family being characterized by a distinct DNA or chromatin binding motif (12). These non-histones decompact the higher-order chromatin structure and promote the binding of nuclear regulatory factors (1,12,49,58). Footprinting analysis and in vitro binding assays (29,64) showed that the chromatin binding sites of the HMG proteins are similar to those of H1 and suggested that HMG proteins and H1 compete for the same binding sites, and recent photobleaching experiments demonstrated that HMGN proteins affect the binding of H1 to chromatin in living cells (16). Photobleaching techniques like fluorescence recovery after photobleaching (FRAP), which is used...

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Section: Discussionmentioning

confidence: 99%

mentioning

confidence: 99%

Network of Dynamic Interactions between Histone H1 and High-Mobility-Group Proteins in Chromatin

Catez

Yang

Tracey

et al. 2004

Molecular and Cellular Biology

246

262

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“…HMG proteins and histone H1 bind to similar sites on chromatin and can compete with each other for chromatin binding (21,22,60,148). Consequently, Ishikawa and coworkers proposed that HMGA proteins displace histone H1 from SAHF (45).…”

Section: Incorporation Of Other Sahf Componentsmentioning

confidence: 99%

Remodeling of chromatin structure in senescent cells and its potential impact on tumor suppression and aging

Adams

2007

Gene

162

135

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Cellular senescence is an important tumor suppression process, and a possible contributor to tissue aging. Senescence is accompanied extensive changes in chromatin structure. In particular, many senescent cells accumulate specialized domains of facultative heterochromatin, called Senescence Associated Heterochromatin Foci (SAHF), which are thought to repress expression of proliferationpromoting genes, thereby contributing to senescence-associated proliferation arrest. This article reviews our current understanding of the structure, assembly and function of these SAHF at a cellular level. The possible contribution of SAHF to tumor suppression and tissue aging is also critically discussed.

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“…Footprinting analysis and in vitro binding assays (26,27) showed that the chromatin binding sites of histone H1 are similar to those of the high mobility group (HMG) proteins, and suggested that histone H1 and HMG proteins compete for the same binding sites.…”

Section: Discussionmentioning

confidence: 99%

Potential role of β-elemene on histone H1 in the H22 ascites hepatoma cell line

2012

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Abstract. β-elemene is extracted from the Chinese medicinal herb Curcuma Wenyujin. It has a broad-spectrum antitumor effect on many types of cancer. However, the exact mechanism of action of β-elemene in hepatocellular carcinoma (HCC) remains unknown. Histone H1 is thought to act as a repressor of transcription by promoting the compaction of chromatin into higher order structures. We found that histone H1 plays an important role in the antitumor function of β-elemene. In this study, histone H1 expression in the H22 murine hepatocellular carcinoma cell line was confirmed, with P388D1 cells serving as a positive control. Furthermore, H22 cells were cultured with β-elemene for different time-points in vitro and treated with different dose-dependent β-elemene in an experimental H22 HCC xenograft transplantation model to confirm whether β-elemene inhibited the growth of H22 tumor cells. In addition, measurements of histone H1 expression both in vitro and in vivo enabled us to demonstrate that β-elemene affects the expression of histone H1 only at the protein level, but is not involved in regulation at the gene level. Our results clearly show that the effect of β-elemene on inhibiting the growth of H22 tumor cells is time-and dose-dependent. In conclusion, β-elemene inhibits the growth of H22 cells by enhancing the expression of histone H1 only at the protein level. This finding may provide insight into a new mechanism of the antitumor action of β-elemene.

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Linker histones versus HMG1/2: a struggle for dominance?

Cited by 54 publications

References 51 publications

Network of Dynamic Interactions between Histone H1 and High-Mobility-Group Proteins in Chromatin

Network of Dynamic Interactions between Histone H1 and High-Mobility-Group Proteins in Chromatin

Remodeling of chromatin structure in senescent cells and its potential impact on tumor suppression and aging

Potential role of β-elemene on histone H1 in the H22 ascites hepatoma cell line

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