Model Animal Research Center, MOE Key Laboratory of Model Animal for Disease Research, Medical School, Nanjing University, China.
BMB Rep. 2011 Jul;44(7):490-5. doi: 10.5483/BMBRep.2011.44.7.490.
Transcription factor AP-2α involves in the process of mammalian embryonic development and tumorigenesis. Many studies have shown that AP-2α functions in association with other interacting proteins. In a two-hybrid screening, the regulatory subunit β of protein casein kinase 2 (CK2β) was identified as an interacting protein of AP-2α; we confirmed this interaction using in-vitro GST pull-down and in-vivo co-immunoprecipitation assays; in an endogenous co-immunoprecipitation experiment, we further found the catalytic subunit α of protein casein kinase 2 (CK2α) also exists in the complex. Phosphorylation analysis revealed that AP-2α was phosphorylated by CK2 kinase majorly at the site of Ser429, and such phosphorylation could be blocked by CK2 specific inhibitor 4,5,6,7-tetrabromobenzotriazole (TBB) in a dose-dependent manner. Luciferase assays demonstrated that both CK2α and CK2β enhanced the transcription activity of AP-2α; moreover, CK2β increased the stability of AP-2α. Our data suggest a novel cellular function of CK-2 as a transcriptional co-activator of AP-2α.
转录因子 AP-2α 参与哺乳动物胚胎发育和肿瘤发生的过程。许多研究表明，AP-2α 与其他相互作用的蛋白质共同发挥作用。在双杂交筛选中，蛋白激酶 CK2 的调节亚基β（CK2β）被鉴定为 AP-2α 的相互作用蛋白；我们使用体外 GST 下拉和体内共免疫沉淀实验证实了这种相互作用；在一个内源性共免疫沉淀实验中，我们进一步发现蛋白激酶 CK2 的催化亚基α（CK2α）也存在于复合物中。磷酸化分析表明，AP-2α 主要在丝氨酸 429 位点被 CK2 激酶磷酸化，这种磷酸化可以被 CK2 特异性抑制剂 4,5,6,7-四溴苯并三唑（TBB）以剂量依赖的方式阻断。荧光素酶实验表明，CK2α 和 CK2β 均增强了 AP-2α 的转录活性；此外，CK2β 增加了 AP-2α 的稳定性。我们的数据表明 CK-2 作为 AP-2α 的转录共激活因子具有新的细胞功能。
