HP1α is not necessary for the structural maintenance of centromeric heterochromatin

Velichko, Artem K.; Kantidze, Omar L.; Razin, Sergey V.

doi:10.4161/epi.6.3.13866

Cited by 4 publications

(6 citation statements)

References 60 publications

(61 reference statements)

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“…Although these proteins have different functions, their dynamics under HS conditions are very similar. All of them, which have confined specific subnuclear localisation sites, are distributed throughout the nucleoplasm in response to HS, as shown herein and in other studies (Wang et al, 2001 Vanderwaal et al, ; Velichko et al, , 2012). Among these factors, the role of nucleolin in the heat stress response is the one most studied; experimental evidence suggests that nucleolin binds the eukaryotic single‐strand binding protein, RPA, and inhibits DNA replication (Wang et al, ).…”

Section: Discussionsupporting

confidence: 84%

“…The breast cancer cell line, MCF7, was chosen as our primary experimental model. Cells were cultivated at 45.5°C for 30 min; we have reported previously that these conditions represent a HS, as determined by the activation of expression of HSPs (Velichko et al, , ). Moreover, a 45.5‐degree HS is physiologically relevant and does not affect cell viability (Velichko et al, ).…”

Section: Resultsmentioning

confidence: 99%

“…The functions of the other proteins, mentioned above under HS conditions, are not nearly as well characterised. For example, HP1, which is relocated from centromeres to undefined genomic loci in response to HS, is only considered as a potential transcriptional repressor acting during HS (Velichko et al, ). We have demonstrated that another well‐studied nuclear protein, TRF2, is redistributed in the nucleus in response to HS.…”

Section: Discussionmentioning

confidence: 99%

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Heat shock‐induced dissociation of TRF2 from telomeres does not initiate a telomere‐dependent DNA damage response

Petrova

Velichko

Kantidze

et al. 2014

Cell Biology International

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Telomeric repeat binding factor 2 (TRF2) is a well-studied shelterin complex subunit that plays a major role in the protection of chomosome ends and the prevention of the telomere-associated DNA damage response. We show that heat shock induces the dissociation of TRF2 from telomeres in human primary and cancer cell cultures. TRF2 is not simply degraded in response to heat shock, but redistributed thoughout the nucleoplasm. This TRF2 depletion/redistribution does not initiate the DNA damage response at chomosome termini.

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Section: Discussionsupporting

confidence: 84%

Section: Resultsmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Heat shock‐induced dissociation of TRF2 from telomeres does not initiate a telomere‐dependent DNA damage response

Petrova

Velichko

Kantidze

et al. 2014

Cell Biology International

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“…HS slightly reduced H3K9Me3 at periCEN in control-depleted cells; this data may explain recent observation that loading of HP1 (that is H3K9Me3-dependent) is diminished in response to HS. 29 At 37°C, depletion of Daxx resulted in reduction of H3K4Me2 levels at CEN [α-satellite, Fig. 4 left top, (p < 0.01)].…”

Section: Hs Increases Accumulation Of Daxx At Cen/pericen Daxx Is Mamentioning

confidence: 99%

Dualistic function of Daxx at centromeric and pericentromeric heterochromatin in normal and stress conditions

Morozov

Gavrilova²,

Ogryzko

et al. 2012

Nucleus

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Nuclear structures ND10/PML NBs are linked to multiple processes, including the maintenance of intranuclear homeostasis by sequestering proteins into "nuclear depot." This function presumes release of proteins from PML NBs and their redistribution to the alternative, supposedly "active" locations, in response to the external stress application. To further investigate this nuclear depot function, we focused on the intranuclear distribution of protein Daxx that in normal conditions is mainly accumulated at PML NBs, and has a minor association with centromeres and pericentromeres (CEN/periCEN). Here we report that application of physiological Heat Shock (HS) changes this balance forcing very robust and reversible accumulation of Daxx on CEN/periCEN heterochromatin. Heterochromatin architecture is essential for the proper orchestration of nuclear processes, while transcription from this part of genome is required for its maintenance. To understand functional consequences of Daxx deposition at CEN/periCEN, we tested for Daxx-dependency of heterochromatin transcription. Depletion of Daxx reduces accumulation of CEN RNA in normal conditions and periCEN RNA after HS application. Searching for the mechanism of Daxx-dependent regulation of heterochromatin transcription, we found that depletion of Daxx decreases incorporation of transcription-associated histone H3 variant, H3.3, into both CEN and periCEN. Surprisingly, HS-induced deposition of Daxx does not further elevate incorporation of H3.3 into CEN/periCEN that remained steady during stress and recovery. Instead, depletion of Daxx leads to HS-induced changes in the balance of epigenetic modifications at heterochromatin, most dramatically elevating levels of active H3K4Me2 modification at periCEN. We propose dualistic function of Daxx-containing complexes at CEN/periCEN: (1) regulation of H3.3 loading in normal conditions and (2) protection of epigenetic status upon stress-induced accumulation, thus collectively guarding epigenetic identity of CEN/periCEN heterochromatin.

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“…Heterochromatin, which contains highly repetitive DNA and is enriched in H3K9me3 and HP1, occurs in pericentric and subtelomeric regions in the majority of eukaryotes. However, it should be noted that neither HP1 [173,174] nor H3K9 trimethylation [175] is essential for maintaining the heterochromatic chromocenters containing pericentric DNA. In addition, H3K9me3 domains that usually correspond to individual silent genes occur in chromosome arms.…”

Section: Introductionmentioning

confidence: 99%

Nucleosomal packaging of eukaryotic DNA and regulation of transcription

2014

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The eukaryotic nucleus harbors genomic DNA, which is tens of thousands of times greater in linear size than the nuclear diameter. Its high condensation is due to DNA packaging in chromatin, and DNA wrapping around nucleosomal globules is a key step in the process. A histone octamer, which forms the nucleosomal globule, interacts with DNA via electrostatic contacts. DNA-histone interactions are rather tight and prevent nucleosomal DNA from being accessed by various enzymes and transcription factors. At the same time, nucleosomes do not prevent transcription and other processes related to the genetic function of DNA. The review considers the structure and diversity of nucleosomes and the central role they play in regulating transcription. Special emphasis is placed on how internucleosomal interactions contribute to genome accessibility to transcription machinery and how nucleosomes are removed from regulatory elements and transcription units in a controlled manner during transcription elongation.

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HP1α is not necessary for the structural maintenance of centromeric heterochromatin

Cited by 4 publications

References 60 publications

Heat shock‐induced dissociation of TRF2 from telomeres does not initiate a telomere‐dependent DNA damage response

Heat shock‐induced dissociation of TRF2 from telomeres does not initiate a telomere‐dependent DNA damage response

Dualistic function of Daxx at centromeric and pericentromeric heterochromatin in normal and stress conditions

Nucleosomal packaging of eukaryotic DNA and regulation of transcription

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