Increased phosphorylation of the carboxyl-terminal domain of RNA polymerase II and loading of polyadenylation and cotranscriptional factors contribute to regulation of the Ig heavy chain mRNA in plasma cells
Increased phosphorylation of the carboxyl-terminal domain of RNA polymerase II and loading of polyadenylation and cotranscriptional factors contribute to regulation of the Ig heavy chain mRNA in plasma cells
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DOI：
10.4049/jimmunol.179.11.7663
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发表时间：
2007-12-01
影响因子：
4.4
通讯作者：
Milcarek, Christine
中科院分区：
文献类型：
--
作者：
Shell, Scott A.;Martincic, Kathleen;Milcarek, Christine
B 细胞产生 Ig H 链 (IgH) mRNA 和蛋白质，主要是膜结合的特定形式。浆细胞产生的 IgH mRNA 量高出 20 至 50 倍，其中大部分被加工成分泌特异性形式；这种转变是由 RNA 加工的实质性变化介导的，但 IgH 转录率仅小幅增加。我们研究了 IgG2a H 链基因上 RNA 聚合酶 II (RNAP-II) 的负载和 C 端结构域 (CTD) 的磷酸化，比较了代表 B (A20) 和浆细胞 (AxJ) 的两种小鼠细胞系，它们表达相同的 H 链基因，但其 RNA 以不同的方式加工。使用染色质免疫沉淀和实时 PCR，我们检测到浆细胞中靠近 IgH 启动子的 RNAP-II CTD 的 RNAP-II 以及 Ser-2 和 Ser-5 磷酸化增加。与 A20 细胞相比，我们检测到 AxJ 中 IgH 基因 5' 端的几个 3' 端加工因子 ELL2 和 PC4 的关联性增加。聚合酶进展和因子关联受到 5,6-二氯苯并咪唑核苷的抑制，5,6-二氯苯并咪唑核苷是一种干扰 Ser-2 添加到 RNAP-II 的 CTD 的药物。总而言之，这些数据表明 CTD 磷酸化和聚合酶上的聚腺苷酸化/ELL2/PC4 因子负载在选择 IgH 基因的分泌性 Poly(A) 位点中的作用。
B cells produce Ig H chain (IgH) mRNA and protein, primarily of the membrane-bound specific form. Plasma cells produce 20- to 50-fold higher amounts of IgH mRNA, most processed to the secretory specific form; this shift is mediated by substantial changes in RNA processing but only a small increase in IgH transcription rate. We investigated RNA polymerase II (RNAP-II) loading and phosphorylation of its C-terminal domain (CTD) on the IgG2a H chain gene, comparing two mouse cell lines representing B (A20) and plasma cells (AxJ) that express the identical H chain gene whose RNA is processed in different ways. Using chromatin immunoprecipitation and real-time PCR, we detected increased RNAP-II and Ser-2 and Ser-5 phosphorylation of RNAP-II CTD close to the IgH promoter in plasma cells. We detected increased association of several 3' end-processing factors, ELL2 and PC4, at the 5' end of the IgH gene in AxJ as compared with A20 cells. Polymerase progress and factor associations were inhibited by 5,6-dichlorobenzimidazole riboside, a drug that interferes with the addition of the Ser-2 to the CTD of RNAP-II. Taken together, these data indicate a role for CTD phosphorylation and polyadenylation/ELL2/PC4 factor loading on the polymerase in the choice of the secretory poly(A) site for the IgH gene.