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SATB1 Mediates Long-Range Chromatin Interactions: A Dual Regulator of Anti-Apoptotic BCL2 and Pro-Apoptotic NOXA Genes.

Yang Y, Wang Z, Sun L, Shao L, Yang N, Yu D, Zhang X, Han X, Sun Y - PLoS ONE (2015)

Bottom Line: Decreased SATB1 levels switched the mbr-BCL2 loop to mbr-NOXA loop, and thus changed expression of these two genes.The SATB1-mediated dynamic switch of the chromatin loop structures was essential for the cooperative expression of the BCL2 and NOXA genes in apoptosis.Notably, the role of SATB1 was specific, since inhibition of SATB1 degradation by caspase-6 inhibitor or caspase-6-resistant SATB1 mutant reversed expression of BCL-2 and NOXA in response to apoptotic stimulation.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Human Functional Genomics of Jiangsu Province, Nanjing medical University, Nanjing, PR China; Department of Cell Biology, Nanjing Medical University, Nanjing, PR China.

ABSTRACT
Aberrant expression of special AT-rich binding protein 1 (SATB1), a global genomic organizer, has been associated with various cancers, which raises the question of how higher-order chromatin structure contributes to carcinogenesis. Disruption of apoptosis is one of the hallmarks of cancer. We previously demonstrated that SATB1 mediated specific long-range chromosomal interactions between the mbr enhancer located within 3'-UTR of the BCL2 gene and the promoter to regulate BCL2 expression during early apoptosis. In the present study, we used chromosome conformation capture (3C) assays and molecular analyses to further investigate the function of the SATB1-mediated higher-order chromatin structure in co-regulation of the anti-apoptotic BCL2 gene and the pro-apoptotic NOXA gene located 3.4Mb downstream on Chromosome 18. We demonstrated that the mbr enhancer spatially juxtaposed the promoters of BCL2 and NOXA genes through SATB1-mediated chromatin-loop in Jurkat cells. Decreased SATB1 levels switched the mbr-BCL2 loop to mbr-NOXA loop, and thus changed expression of these two genes. The SATB1-mediated dynamic switch of the chromatin loop structures was essential for the cooperative expression of the BCL2 and NOXA genes in apoptosis. Notably, the role of SATB1 was specific, since inhibition of SATB1 degradation by caspase-6 inhibitor or caspase-6-resistant SATB1 mutant reversed expression of BCL-2 and NOXA in response to apoptotic stimulation. This study reveals the critical role of SATB1-organized higher-order chromatin structure in regulating the dynamic equilibrium of apoptosis-controlling genes with antagonistic functions and suggests that aberrant SATB1 expression might contribute to cancer development by disrupting the co-regulated genes in apoptosis pathways.

No MeSH data available.


Related in: MedlinePlus

SATB1-induced chromatin loop conversion in the co-regulation of the BCL2 and NOXA genes in cellular response to apoptosis.Jurkat cells were treated with 5μM camptothecin for 2 h to induce apoptosis, and were subsequently harvested. The vehicle control for camptothecin is an equal volume of DMSO. The apoptosis rates were determined by FCM (A) and the degradation of SATB1 was confirmed by Western blot analysis (B). The distal chromatin interactions and gene transcriptional activities were determined by q-3C assays and real-time PCR. The frequency of mbr-BCL2 chromatin loop was significantly reduced, while the frequency of mbr-NOXA chromatin loop was increased in camptothecin-treated cells (C). These findings were coupled with opposite changes in mRNA levels of the BCL2 and NOXA genes (D). These results, together with those described above, suggested that SATB1 was able to co-regulate expression of the BCL2 and NOXA genes at the high-order chromatin structure level.
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pone.0139170.g004: SATB1-induced chromatin loop conversion in the co-regulation of the BCL2 and NOXA genes in cellular response to apoptosis.Jurkat cells were treated with 5μM camptothecin for 2 h to induce apoptosis, and were subsequently harvested. The vehicle control for camptothecin is an equal volume of DMSO. The apoptosis rates were determined by FCM (A) and the degradation of SATB1 was confirmed by Western blot analysis (B). The distal chromatin interactions and gene transcriptional activities were determined by q-3C assays and real-time PCR. The frequency of mbr-BCL2 chromatin loop was significantly reduced, while the frequency of mbr-NOXA chromatin loop was increased in camptothecin-treated cells (C). These findings were coupled with opposite changes in mRNA levels of the BCL2 and NOXA genes (D). These results, together with those described above, suggested that SATB1 was able to co-regulate expression of the BCL2 and NOXA genes at the high-order chromatin structure level.

Mentions: Apoptosis is a biological process tightly regulated by the pro-apoptotic and anti-apoptotic proteins. To address whether the SATB1-mediated chromatin loop conversion was involved in regulation of the cooperative response of the BCL2 and NOXA genes to apoptosis stimulation, we analyzed the change in chromatin loops, transcriptional activity of the genes, and SATB1 level in Jurkat cells treated with camptothecin. Cells were incubated with 5μM camptothecin and harvested after 2 h, when early apoptosis occurred and SATB1 was degraded to 70%. (Fig 4). The chromatin loop conversion was determined by quantitative 3C assays (q-3C). As indicated in Fig 4, the frequency of interaction between the BCL2 promoter and mbr (mbr-BCL2 chromatin loop) was significantly reduced, while the frequency of interaction between the NOXA promoter and mbr (mbr-NOXA chromatin loop) was increased in camptothecin-treated cells. Consistently, real-time PCR results showed that camptothecin treatment induced opposite changes in mRNA levels of the BCL2 and NOXA genes. The BCL2 mRNA decreased by 50%, while the NOXA mRNA increased by approximately two folds (Fig 4). These data indicated that the.SATB1-mediated conversion between the mbr-BCL2 chromatin loop and the mbr-NOXA chromatin loop was directly involved in the coordinated regulation of the BCL2 and NOXA genes in the cellular apoptotic response.


SATB1 Mediates Long-Range Chromatin Interactions: A Dual Regulator of Anti-Apoptotic BCL2 and Pro-Apoptotic NOXA Genes.

Yang Y, Wang Z, Sun L, Shao L, Yang N, Yu D, Zhang X, Han X, Sun Y - PLoS ONE (2015)

SATB1-induced chromatin loop conversion in the co-regulation of the BCL2 and NOXA genes in cellular response to apoptosis.Jurkat cells were treated with 5μM camptothecin for 2 h to induce apoptosis, and were subsequently harvested. The vehicle control for camptothecin is an equal volume of DMSO. The apoptosis rates were determined by FCM (A) and the degradation of SATB1 was confirmed by Western blot analysis (B). The distal chromatin interactions and gene transcriptional activities were determined by q-3C assays and real-time PCR. The frequency of mbr-BCL2 chromatin loop was significantly reduced, while the frequency of mbr-NOXA chromatin loop was increased in camptothecin-treated cells (C). These findings were coupled with opposite changes in mRNA levels of the BCL2 and NOXA genes (D). These results, together with those described above, suggested that SATB1 was able to co-regulate expression of the BCL2 and NOXA genes at the high-order chromatin structure level.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4589335&req=5

pone.0139170.g004: SATB1-induced chromatin loop conversion in the co-regulation of the BCL2 and NOXA genes in cellular response to apoptosis.Jurkat cells were treated with 5μM camptothecin for 2 h to induce apoptosis, and were subsequently harvested. The vehicle control for camptothecin is an equal volume of DMSO. The apoptosis rates were determined by FCM (A) and the degradation of SATB1 was confirmed by Western blot analysis (B). The distal chromatin interactions and gene transcriptional activities were determined by q-3C assays and real-time PCR. The frequency of mbr-BCL2 chromatin loop was significantly reduced, while the frequency of mbr-NOXA chromatin loop was increased in camptothecin-treated cells (C). These findings were coupled with opposite changes in mRNA levels of the BCL2 and NOXA genes (D). These results, together with those described above, suggested that SATB1 was able to co-regulate expression of the BCL2 and NOXA genes at the high-order chromatin structure level.
Mentions: Apoptosis is a biological process tightly regulated by the pro-apoptotic and anti-apoptotic proteins. To address whether the SATB1-mediated chromatin loop conversion was involved in regulation of the cooperative response of the BCL2 and NOXA genes to apoptosis stimulation, we analyzed the change in chromatin loops, transcriptional activity of the genes, and SATB1 level in Jurkat cells treated with camptothecin. Cells were incubated with 5μM camptothecin and harvested after 2 h, when early apoptosis occurred and SATB1 was degraded to 70%. (Fig 4). The chromatin loop conversion was determined by quantitative 3C assays (q-3C). As indicated in Fig 4, the frequency of interaction between the BCL2 promoter and mbr (mbr-BCL2 chromatin loop) was significantly reduced, while the frequency of interaction between the NOXA promoter and mbr (mbr-NOXA chromatin loop) was increased in camptothecin-treated cells. Consistently, real-time PCR results showed that camptothecin treatment induced opposite changes in mRNA levels of the BCL2 and NOXA genes. The BCL2 mRNA decreased by 50%, while the NOXA mRNA increased by approximately two folds (Fig 4). These data indicated that the.SATB1-mediated conversion between the mbr-BCL2 chromatin loop and the mbr-NOXA chromatin loop was directly involved in the coordinated regulation of the BCL2 and NOXA genes in the cellular apoptotic response.

Bottom Line: Decreased SATB1 levels switched the mbr-BCL2 loop to mbr-NOXA loop, and thus changed expression of these two genes.The SATB1-mediated dynamic switch of the chromatin loop structures was essential for the cooperative expression of the BCL2 and NOXA genes in apoptosis.Notably, the role of SATB1 was specific, since inhibition of SATB1 degradation by caspase-6 inhibitor or caspase-6-resistant SATB1 mutant reversed expression of BCL-2 and NOXA in response to apoptotic stimulation.

View Article: PubMed Central - PubMed

Affiliation: Key Laboratory of Human Functional Genomics of Jiangsu Province, Nanjing medical University, Nanjing, PR China; Department of Cell Biology, Nanjing Medical University, Nanjing, PR China.

ABSTRACT
Aberrant expression of special AT-rich binding protein 1 (SATB1), a global genomic organizer, has been associated with various cancers, which raises the question of how higher-order chromatin structure contributes to carcinogenesis. Disruption of apoptosis is one of the hallmarks of cancer. We previously demonstrated that SATB1 mediated specific long-range chromosomal interactions between the mbr enhancer located within 3'-UTR of the BCL2 gene and the promoter to regulate BCL2 expression during early apoptosis. In the present study, we used chromosome conformation capture (3C) assays and molecular analyses to further investigate the function of the SATB1-mediated higher-order chromatin structure in co-regulation of the anti-apoptotic BCL2 gene and the pro-apoptotic NOXA gene located 3.4Mb downstream on Chromosome 18. We demonstrated that the mbr enhancer spatially juxtaposed the promoters of BCL2 and NOXA genes through SATB1-mediated chromatin-loop in Jurkat cells. Decreased SATB1 levels switched the mbr-BCL2 loop to mbr-NOXA loop, and thus changed expression of these two genes. The SATB1-mediated dynamic switch of the chromatin loop structures was essential for the cooperative expression of the BCL2 and NOXA genes in apoptosis. Notably, the role of SATB1 was specific, since inhibition of SATB1 degradation by caspase-6 inhibitor or caspase-6-resistant SATB1 mutant reversed expression of BCL-2 and NOXA in response to apoptotic stimulation. This study reveals the critical role of SATB1-organized higher-order chromatin structure in regulating the dynamic equilibrium of apoptosis-controlling genes with antagonistic functions and suggests that aberrant SATB1 expression might contribute to cancer development by disrupting the co-regulated genes in apoptosis pathways.

No MeSH data available.


Related in: MedlinePlus