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Stress-induced transcription of satellite III repeats.

Jolly C, Metz A, Govin J, Vigneron M, Turner BM, Khochbin S, Vourc'h C - J. Cell Biol. (2003)

Bottom Line: These stress-induced structures, which form primarily on the 9q12 region in humans through direct binding of HSF1 to satellite III repeats, do not colocalize with transcription sites of known hsp genes.In this paper, we show that nuclear stress granules correspond to RNA polymerase II transcription factories where satellite III repeats are transcribed into large and stable RNAs that remain associated with the 9q12 region, even throughout mitosis.This work not only reveals the existence of a new major heat-induced transcript in human cells that may play a role in chromatin structure, but also provides evidence for a transcriptional activity within a locus considered so far as heterochromatic and silent.

View Article: PubMed Central - PubMed

Affiliation: INSERM U309, Institut A. Bonniot, 38706 La Tronche cedex, France. caroline.jolly@ujf-grenoble.fr

ABSTRACT
Exposure of mammalian cells to stress induces the activation of heat shock transcription factor 1 (HSF1) and the subsequent transcription of heat shock genes. Activation of the heat shock response also correlates with a rapid relocalization of HSF1 within a few nuclear structures termed nuclear stress granules. These stress-induced structures, which form primarily on the 9q12 region in humans through direct binding of HSF1 to satellite III repeats, do not colocalize with transcription sites of known hsp genes. In this paper, we show that nuclear stress granules correspond to RNA polymerase II transcription factories where satellite III repeats are transcribed into large and stable RNAs that remain associated with the 9q12 region, even throughout mitosis. This work not only reveals the existence of a new major heat-induced transcript in human cells that may play a role in chromatin structure, but also provides evidence for a transcriptional activity within a locus considered so far as heterochromatic and silent.

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CBP is recruited to nuclear stress granules during heat shock. Transiently expressed CBP-HA (red) was codetected with HSF1 (green) in HeLa cells. In non–heat-shocked cells, CBP displays a fine punctate staining dispersed throughout the nucleoplasm. At 42°C, a fraction of the protein colocalizes with HSF1 in the granules. Bar, 5 μm.
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fig3: CBP is recruited to nuclear stress granules during heat shock. Transiently expressed CBP-HA (red) was codetected with HSF1 (green) in HeLa cells. In non–heat-shocked cells, CBP displays a fine punctate staining dispersed throughout the nucleoplasm. At 42°C, a fraction of the protein colocalizes with HSF1 in the granules. Bar, 5 μm.

Mentions: To confirm that the presence of acetylated histones within the granules is a stress-induced event, we investigated the possibility that a histone acetyltransferase (HAT) is also recruited to the granules upon stress. Therefore, we analyzed the distribution of transiently expressed fusion proteins encoding either GCN5, Tip60, or CREB binding protein (CBP) in HeLa cells (Col et al., 2001; Legube et al., 2002). GCN5 and Tip60 both displayed a punctate nuclear staining that was unaffected by stress (unpublished data). In contrast, a fraction of the overexpressed CBP protein was detected at 42°C in a few granular structures that coincided with HSF1-containing granules, in addition to the persisting punctate nucleoplasmic staining (Fig. 3). CBP is thus able to relocate to the granules during stress, likely accounting for the stress-induced accumulation of acetylated histones within these structures.


Stress-induced transcription of satellite III repeats.

Jolly C, Metz A, Govin J, Vigneron M, Turner BM, Khochbin S, Vourc'h C - J. Cell Biol. (2003)

CBP is recruited to nuclear stress granules during heat shock. Transiently expressed CBP-HA (red) was codetected with HSF1 (green) in HeLa cells. In non–heat-shocked cells, CBP displays a fine punctate staining dispersed throughout the nucleoplasm. At 42°C, a fraction of the protein colocalizes with HSF1 in the granules. Bar, 5 μm.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC2171959&req=5

fig3: CBP is recruited to nuclear stress granules during heat shock. Transiently expressed CBP-HA (red) was codetected with HSF1 (green) in HeLa cells. In non–heat-shocked cells, CBP displays a fine punctate staining dispersed throughout the nucleoplasm. At 42°C, a fraction of the protein colocalizes with HSF1 in the granules. Bar, 5 μm.
Mentions: To confirm that the presence of acetylated histones within the granules is a stress-induced event, we investigated the possibility that a histone acetyltransferase (HAT) is also recruited to the granules upon stress. Therefore, we analyzed the distribution of transiently expressed fusion proteins encoding either GCN5, Tip60, or CREB binding protein (CBP) in HeLa cells (Col et al., 2001; Legube et al., 2002). GCN5 and Tip60 both displayed a punctate nuclear staining that was unaffected by stress (unpublished data). In contrast, a fraction of the overexpressed CBP protein was detected at 42°C in a few granular structures that coincided with HSF1-containing granules, in addition to the persisting punctate nucleoplasmic staining (Fig. 3). CBP is thus able to relocate to the granules during stress, likely accounting for the stress-induced accumulation of acetylated histones within these structures.

Bottom Line: These stress-induced structures, which form primarily on the 9q12 region in humans through direct binding of HSF1 to satellite III repeats, do not colocalize with transcription sites of known hsp genes.In this paper, we show that nuclear stress granules correspond to RNA polymerase II transcription factories where satellite III repeats are transcribed into large and stable RNAs that remain associated with the 9q12 region, even throughout mitosis.This work not only reveals the existence of a new major heat-induced transcript in human cells that may play a role in chromatin structure, but also provides evidence for a transcriptional activity within a locus considered so far as heterochromatic and silent.

View Article: PubMed Central - PubMed

Affiliation: INSERM U309, Institut A. Bonniot, 38706 La Tronche cedex, France. caroline.jolly@ujf-grenoble.fr

ABSTRACT
Exposure of mammalian cells to stress induces the activation of heat shock transcription factor 1 (HSF1) and the subsequent transcription of heat shock genes. Activation of the heat shock response also correlates with a rapid relocalization of HSF1 within a few nuclear structures termed nuclear stress granules. These stress-induced structures, which form primarily on the 9q12 region in humans through direct binding of HSF1 to satellite III repeats, do not colocalize with transcription sites of known hsp genes. In this paper, we show that nuclear stress granules correspond to RNA polymerase II transcription factories where satellite III repeats are transcribed into large and stable RNAs that remain associated with the 9q12 region, even throughout mitosis. This work not only reveals the existence of a new major heat-induced transcript in human cells that may play a role in chromatin structure, but also provides evidence for a transcriptional activity within a locus considered so far as heterochromatic and silent.

Show MeSH
Related in: MedlinePlus