Department of Molecular and Cell Biology, The University of Texas at Dallas, Richardson, Texas, United States of America.
PLoS One. 2013 Nov 6;8(11):e78253. doi: 10.1371/journal.pone.0078253. eCollection 2013.
The upstream Gγ-globin cAMP-response element (G-CRE) plays an important role in regulating Gγ-globin expression through binding of ATF2 and its DNA-binding partners defined in this study. ATF2 knockdown resulted in a significant reduction of γ-globin expression accompanied by decreased ATF2 binding to the G-CRE. By contrast, stable ATF2 expression in K562 cells increased γ-globin transcription which was reduced by ATF2 knockdown. Moreover, a similar effect of ATF2 on γ-globin expression was observed in primary erythroid progenitors. To understand the role of ATF2 in γ-globin expression, chromatographically purified G-CRE/ATF2-interacting proteins were subjected to mass spectrometry analysis; major binding partners included CREB1, cJun, Brg1, and histone deacetylases among others. Immunoprecipitation assays demonstrated interaction of these proteins with ATF2 and in vivo GCRE binding in CD34(+) cells undergoing erythroid differentiation which was correlated with γ-globin expression during development. These results suggest synergism between developmental stage-specific recruitments of the ATF2 protein complex and expression of γ-globin during erythropoiesis. Microarray studies in K562 cells support ATF2 plays diverse roles in hematopoiesis and chromatin remodeling.
上游 Gγ-珠蛋白 cAMP 反应元件 (G-CRE) 通过结合本研究中定义的 ATF2 及其 DNA 结合伙伴，在调节 Gγ-珠蛋白表达中发挥重要作用。ATF2 敲低导致 γ-珠蛋白表达显著减少，同时 ATF2 与 G-CRE 的结合减少。相比之下，K562 细胞中稳定表达的 ATF2 增加了 γ-珠蛋白转录，而 ATF2 敲低则降低了 γ-珠蛋白转录。此外，在原代红细胞祖细胞中也观察到 ATF2 对 γ-珠蛋白表达的类似影响。为了了解 ATF2 在 γ-珠蛋白表达中的作用，对色谱纯化的 G-CRE/ATF2 相互作用蛋白进行了质谱分析；主要结合伙伴包括 CREB1、cJun、Brg1 和组蛋白去乙酰化酶等。免疫沉淀试验表明这些蛋白与 ATF2 相互作用，并在经历红细胞分化的 CD34(+) 细胞中体内结合 GCRE，这与发育过程中 γ-珠蛋白表达相关。这些结果表明，ATF2 蛋白复合物的发育阶段特异性募集与红细胞生成过程中 γ-珠蛋白的表达之间存在协同作用。K562 细胞中的微阵列研究支持 ATF2 在造血和染色质重塑中发挥多种作用。
