Department of Molecular and Cell Biology, University of Texas at Dallas, Richardson, TX 75080, USA.
Blood Cells Mol Dis. 2011 Jun 15;47(1):12-22. doi: 10.1016/j.bcmd.2011.03.003. Epub 2011 Apr 15.
In response to sodium butyrate and trichostatin A treatment in erythroid cells, p38 mitogen activated protein kinase (MAPK) mediates fetal hemoglobin (HbF) induction by activating cAMP response element binding protein 1 (CREB1). To expand on this observation, we completed studies to determine the role of p38 MAPK in steady-state γ-globin regulation. We propose that p38 signaling regulates Gγ-globin transcription during erythroid maturation through its downstream effector CREB1 which binds the Gγ-globin cAMP response element (G-CRE). We demonstrated that a loss of p38 or CREB1 function by siRNA knockdown resulted in target gene silencing. Moreover, gain of p38 or CREB1 function augments γ-globin transcription. These regulatory effects were conserved under physiological conditions tested in primary erythroid cells. When the G-CRE was mutated in a stable chromatin environment Gγ-globin promoter activity was nearly abolished. Furthermore, introduction of mutations in the G-CRE abolished Gγ-globin activation via p38 MAPK/CREB1 signaling. Chromatin immunoprecipitation assays (ChIP) demonstrated that CREB1 and its binding partner CREB binding protein (CBP) co-localize at the G-CRE region. These data support the role of p38 MAPK/CREB1 signaling in Gγ-globin gene transcription under steady-state conditions.
针对红系细胞中的丁酸钠和曲古抑菌素 A 处理，丝裂原活化蛋白激酶 p38（MAPK）通过激活 cAMP 反应元件结合蛋白 1（CREB1）介导胎儿血红蛋白（HbF）的诱导。为了进一步研究这一现象，我们完成了研究以确定 p38 MAPK 在稳定状态 γ-珠蛋白调节中的作用。我们提出，p38 信号通过其下游效应物 CREB1 调节红细胞成熟过程中的 Gγ-珠蛋白转录，该效应物结合 Gγ-珠蛋白 cAMP 反应元件（G-CRE）。我们证明，通过 siRNA 敲低丧失 p38 或 CREB1 功能会导致靶基因沉默。此外，p38 或 CREB1 功能的获得增强了 γ-珠蛋白转录。这些调节作用在原代红细胞中测试的生理条件下是保守的。当 G-CRE 在稳定的染色质环境中发生突变时，Gγ-珠蛋白启动子活性几乎被完全抑制。此外，通过 p38 MAPK/CREB1 信号通路引入 G-CRE 突变会消除 Gγ-珠蛋白的激活。染色质免疫沉淀分析（ChIP）表明，CREB1 及其结合伙伴 CREB 结合蛋白（CBP）在 G-CRE 区域共定位。这些数据支持 p38 MAPK/CREB1 信号在稳定状态条件下 Gγ-珠蛋白基因转录中的作用。
