Brd2 is a novel protein kinase and plays a role in cell cycle-responsive transcription. Recent studies show that Brd2 contributes to E2F-1 regulated cell cycle progression. In this process, Brd2 exhibits scaffold or transcriptional adapter functions and mediates recruitment of both E2F-1 transcription factors and chromatin-remodelling activity to the E2F-1-resposive promoter. In the present study, we show that Brd2 is also a TBP-associated protein and a 26 amino acids peptide in the first bromodomain of Brd2 is essential for Brd2-TBP interaction. We found that serum stimulation of serum starved NIH/3T3 cells efficiently induces the formation of the Brd2-E2F-1-TBP complex in vivo. In this process, Brd2 plays a pivotal role in the recruitment of TBP into a E2F-1 transcriptional complex, as tested in overexpression assay and at the endogenous level. Furthermore, the 26 amino acid peptide that mediates Brd2-TBP interaction is proved to be critical for Brd2-dependent transactivation on E2F-1-responsive promoters, and moreover, Brd2 and E2F-1 may cooperatively participate in various serum-induced transactivation processes in Luciferase-reporter assays. Thus taken together, because Brd2 may recruit a HAT in its transactivational complex and E2F-1 has been found to stimulate transcription by recruiting acetyltransferase and cofactors GCN5, we predict that Brd2 and E2F-1 may act in a cooperative way to introduce an optimal environment for TBP binding to the TATA-element of gene promoters.

中文翻译：

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Brd2是与TBP相关的蛋白质，可响应血清刺激而将TBP募集到E2F-1转录复合物中。

Brd2是一种新型的蛋白激酶，在细胞周期反应性转录中起作用。最近的研究表明Brd2有助于E2F-1调节细胞周期进程。在此过程中，Brd2表现出支架或转录衔接子功能，并介导E2F-1转录因子的募集和对E2F-1受体启动子的染色质重塑活性。在本研究中，我们显示Brd2也是TBP相关蛋白，Brd2的第一个溴结构域中的26个氨基酸的肽对于Brd2-TBP相互作用至关重要。我们发现血清刺激血清饥饿的NIH / 3T3细胞有效诱导体内Brd2-E2F-1-TBP复合物的形成。在此过程中，Brd2在将TBP募集到E2F-1转录复合物中的过程中起着关键作用，正如在过表达测定中和在内源性水平上所测试的那样。此外，已证明介导Brd2-TBP相互作用的26个氨基酸肽对于依赖于E2F-1响应启动子的Brd2依赖性反式激活至关重要，而且，Brd2和E2F-1可能协同参与各种血清诱导的反式激活过程。萤光素酶报告基因测定。综上所述，由于Brd2可能在其反式激活复合物中募集HAT，并且已经发现E2F-1通过募集乙酰转移酶和辅助因子GCN5来刺激转录，因此我们预测Brd2和E2F-1可能以协作的方式引入最佳环境。 TBP与基因启动子的TATA元件的结合。Brd2和E2F-1可能参与萤光素酶报告基因测定中各种血清诱导的反式激活过程。综上所述，由于Brd2可能在其反式激活复合物中募集HAT，并且已经发现E2F-1通过募集乙酰转移酶和辅助因子GCN5来刺激转录，因此我们预测Brd2和E2F-1可能以协作的方式引入最佳环境。 TBP与基因启动子的TATA元件的结合。Brd2和E2F-1可能参与萤光素酶报告基因测定中各种血清诱导的反式激活过程。综上所述，由于Brd2可能在其反式激活复合物中募集HAT，并且已经发现E2F-1通过募集乙酰转移酶和辅助因子GCN5来刺激转录，因此我们预测Brd2和E2F-1可能以协作的方式引入最佳环境。 TBP与基因启动子的TATA元件的结合。