Department of Medicine, McGill University, and the McGill University Health Centre Research Institute, Montreal, Quebec, Canada H3A 2B4.
J Cell Biochem. 2011 May;112(5):1268-76. doi: 10.1002/jcb.23018.
We have previously identified the EphA2 receptor tyrosine kinase as a potentially important injury-responsive gene and a transcriptional target of Src kinase activity in renal ischemia-reperfusion injury (IRI). In the present study, we confirmed, using EphA2 gene trap mice that the endogenous EphA2 promoter is strongly activated following renal IRI. We also examined in more detail the mechanisms responsible for Src kinase-induced activation of the -2 kb human EphA2 promoter and found that the minimal Src-responsive elements were contained in the -145 to +137 region of the human EphA2 gene. This region contains a canonical cAMP-responsive element (CRE) that we found to be critical for both basal and Src kinase-induced transcriptional activity. However, despite activation of the prototypical CRE-binding factor CREB by the Src kinase Fyn, siRNA-mediated knockdown of CREB had no significant impact on either basal or Fyn-induced EphA2 promoter activity. Similarly, activation of CREB by the adenylate cyclase agonist forskolin failed to induce EphA2 promoter activation. Thus, Src kinase-induced activation of the EphA2 promoter is CRE-dependent but CREB-independent.
我们之前已经确定 EphA2 受体酪氨酸激酶是一种潜在的重要损伤反应基因，也是肾缺血再灌注损伤 (IRI) 中Src 激酶活性的转录靶标。在本研究中，我们使用 EphA2 基因捕获小鼠证实，内源性 EphA2 启动子在肾 IRI 后被强烈激活。我们还更详细地研究了Src 激酶诱导激活 -2kb 人 EphA2 启动子的机制，发现最小的 Src 反应元件包含在人 EphA2 基因的 -145 到 +137 区域。该区域包含一个典型的 cAMP 反应元件 (CRE)，我们发现该元件对于基础和 Src 激酶诱导的转录活性都至关重要。然而，尽管 Src 激酶 Fyn 激活了典型的 CRE 结合因子 CREB，但 CREB 的 siRNA 介导敲低对基础或 Fyn 诱导的 EphA2 启动子活性均无显著影响。同样，激活剂forskolin 激活 CREB 也未能诱导 EphA2 启动子激活。因此，Src 激酶诱导的 EphA2 启动子激活是 CRE 依赖性的，但与 CREB 无关。
