Rb and p130 regulate RNA polymerase I transcription: Rb disrupts the interaction between UBF and SL-1
Rb and p130 regulate RNA polymerase I transcription: Rb disrupts the interaction between UBF and SL-1
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DOI：
10.1038/sj.onc.1203875
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发表时间：
2000-10-12
期刊：
影响因子：
8
通讯作者：
Rothblum, LI
中科院分区：
文献类型：
--
作者：
Hannan, KM;Hannan, RD;Rothblum, LI
我们之前已经证明，视网膜母细胞瘤易感基因 (Rb) 编码的蛋白质通过抑制 UBF 介导的转录，充当 RNA 聚合酶 I（rDNA 转录）转录的调节因子。在本研究中，我们研究了 Rb 抑制 UBF 依赖性 rDNA 转录的机制，并确定其他 Rb 样蛋白是否具有类似的作用。我们证明了真实或重组的 UBF 和 Rb 直接相互作用，这需要一个功能性的 A/B 口袋。 DNase 足迹和带位移分析表明，Rb 和 UBF 之间的相互作用不会抑制 UBF 与 DNA 的结合，然而，UBF/Rb 复合物的形成确实阻断了 UBF 与 SL-1 的相互作用，正如使用 48 kDa 亚基作为 SL-1 的标记所表明的那样。另外的证据表明，可以在与 UBF 的复合物中发现另一种口袋蛋白 p130，但不是 p107。有趣的是，UBF 的细胞含量在两个生理系统中，p130 与 rDNA 转录速率呈负相关，p130 的过度表达会抑制 rDNA 转录。这些结果表明 p130 可能以与 Rb 类似的方式调节 rDNA 转录。
We have previously demonstrated that the protein encoded by the retinoblastoma susceptibility gene (Rb) functions as a regulator of transcription by RNA polymerase I (rDNA transcription) by inhibiting UBF-mediated transcription. In the present study, we have examined the mechanism by which Rb represses UBF-dependent rDNA transcription and determined if other Rb-like proteins have similar effects. We demonstrate that authentic or recombinant UBF and Rb interact directly and this requires a functional A/B pocket. DNase footprinting and band-shift assays demonstrated that the interaction between Rb and UBF does not inhibit the binding of UBF to DNA, However, the formation of an UBF/Rb complex does block the interaction of UBF with SL-1, as indicated by using the 48 kDa subunit as a marker for SL-1, Additional evidence is presented that another pocket protein, p130 but not p107, can be found in a complex with UBF, Interestingly, the cellular content of p130 inversely correlated with the rate of rDNA transcription in two physiological systems, and overexpression of p130 inhibited rDNA transcription. These results suggest that p130 may regulate rDNA transcription in a similar manner to Rb.