CTCF binds the proximal exonic region of hTERT and inhibits its transcription.
CTCF binds the proximal exonic region of hTERT and inhibits its transcription.
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DOI：
10.1093/nar/gki989
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发表时间：
2005
影响因子：
14.9
通讯作者：
Benhattar J
中科院分区：
文献类型：
--
作者：
Renaud S;Loukinov D;Bosman FT;Lobanenkov V;Benhattar J
催化亚基（hTERT）的表达代表端粒酶活性的限制因素。以前，我们检测到的hTERT基因的近端外显子区（前两个外显子）的转录抑制效应。为了更好地理解所涉及的机制并确定潜在的阻遏物，我们进一步表征了该区域。在hTERT最小启动子下游添加hTERT近端外显子区强烈降低了所有测试细胞（肿瘤、正常和永生化）中的启动子转录活性。无论细胞类型如何，该外显子区域也显著抑制CMV和CDKN2A启动子的转录活性。因此，hTERT外显子区的阻遏作用既不依赖于细胞也不依赖于启动子。然而，启动子和外显子区域之间的距离可以调节这种阻遏作用，这表明核小体定位在转录阻遏中起作用。我们通过电泳迁移率变动分析表明CCCTC结合因子（CTCF）与hTERT的近端外显子区结合。染色质免疫沉淀试验证实了CTCF与该区域的结合。CTCF在hTERT不表达的细胞中与hTERT结合，但在端粒酶阳性的细胞中不结合。此外，CTCF的转录下调RNA干扰去抑制正常端粒酶阴性细胞中hTERT基因的表达。我们的研究结果表明，CTCF通过调节hTERT基因的表达参与了永生的关键细胞机制。
The expression of the catalytic subunit (hTERT) represents the limiting factor for telomerase activity. Previously, we detected a transcriptional repressor effect of the proximal exonic region (first two exons) of the hTERT gene. To better understand the mechanism involved and to identify a potential repressor, we further characterized this region. The addition of the hTERT proximal exonic region downstream of the hTERT minimal promoter strongly reduced promoter transcriptional activity in all cells tested (tumor, normal and immortalized). This exonic region also significantly inhibited the transcriptional activity of the CMV and CDKN2A promoters, regardless of the cell type. Therefore, the repressor effect of hTERT exonic region is neither cell nor promoter-dependent. However, the distance between the promoter and the exonic region can modulate this repressor effect, suggesting that nucleosome positioning plays a role in transcriptional repression. We showed by electrophoretic mobility shift assay that CCCTC-binding factor (CTCF) binds to the proximal exonic region of hTERT. Chromatin immunoprecipitaion assays confirmed the binding of CTCF to this region. CTCF is bound to hTERT in cells in which hTERT is not expressed, but not in telomerase-positive ones. Moreover, the transcriptional downregulation of CTCF by RNA interference derepressed hTERT gene expression in normal telomerase-negative cells. Our results suggest that CTCF participates in key cellular mechanisms underlying immortality by regulating hTERT gene expression.
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DOI：
10.1016/j.bbrc.2004.10.137
发表时间：
2004-12-17
影响因子：
3.1
作者：
Guilleret, I;Benhattar, J
通讯作者：
Benhattar, J
影响因子：
56.9
作者：
FENG, JL;FUNK, WD;VILLEPONTEAU, B
通讯作者：
VILLEPONTEAU, B
影响因子：
9.2
作者：
Beattie, TL;Zhou, W;Harrington, L
通讯作者：
Harrington, L
影响因子：
3.5
作者：
Cong, YS;Wen, JP;Bacchetti, S
通讯作者：
Bacchetti, S
影响因子：
14.9
作者：
Fujimoto, K;Kyo, S;Inoue, M
通讯作者：
Inoue, M