Molecular Signal Transduction Section, Laboratory of Allergic Diseases, NIAID, National Institutes of Health, Bethesda, Maryland 20892, USA.
J Biol Chem. 2011 Jun 24;286(25):22219-26. doi: 10.1074/jbc.M111.228924. Epub 2011 Apr 29.
RGS13, a member of the regulator of G protein signaling (RGS) family, inhibits G protein-coupled receptor signaling in B cells and mast cells (MCs) and suppresses IgE-antigen-induced MC degranulation and anaphylaxis. Although RGS13 expression is induced by immune receptor and chemokine receptor stimulation, the molecular regulation of RGS13 transcription is unknown. Here, we investigated the role of two p53 response elements (REs) in the regulation of RGS13 promoter activity and expression. We found that a 1000-bp DNA fragment upstream of the ATG translation start site (TSS) had promoter activity in reporter gene assays, and deletion or mutation of a p53-binding motif nearest the TSS abolished promoter activity. Notably, p53 bound to both REs in the RGS13 promoter in vivo as assessed by chromatin immunoprecipitation, suggesting that the p53 RE most distal to the TSS is physiologically inactive. We detected reduced RGS13 expression in MCs exogenously expressing p53 or treated with doxorubicin, which induces genotoxic stress and leads to p53 accumulation. RNA silencing of p53 up-regulated RGS13 expression in B lymphocytes, and bone marrow-derived MCs from p53(-/-) mice had increased RGS13 expression. Finally, p53-depleted B cells with increased RGS13 expression had reduced Ca(2+) mobilization in response to sphingosine 1-phosphate. These studies indicate that p53 may modulate immune responses through suppression of RGS13 transcription in MCs and B cells.
RGS13 是 G 蛋白信号调节因子（RGS）家族的成员，可抑制 B 细胞和肥大细胞（MC）中的 G 蛋白偶联受体信号转导，并抑制 IgE-抗原诱导的 MC 脱颗粒和过敏反应。尽管 RGS13 的表达受免疫受体和趋化因子受体刺激诱导，但 RGS13 转录的分子调节尚不清楚。在这里，我们研究了两个 p53 反应元件（RE）在调节 RGS13 启动子活性和表达中的作用。我们发现，在报告基因测定中，起始翻译 ATG 附近 1000bp 的 DNA 片段具有启动子活性，并且靠近 TSS 的 p53 结合基序缺失或突变会使启动子活性丧失。值得注意的是，通过染色质免疫沉淀法评估，p53 在体内与 RGS13 启动子中的两个 RE 结合，这表明与 TSS 最远的 p53 RE 在生理上是无活性的。我们发现，在过表达 p53 或用阿霉素（一种诱导遗传毒性应激并导致 p53 积累的药物）处理的 MC 中，RGS13 的表达减少。在 B 淋巴细胞中，p53 的 RNA 沉默上调了 RGS13 的表达，并且 p53(-/-) 小鼠的骨髓衍生 MC 中 RGS13 的表达增加。最后，p53 耗尽的 B 细胞中 RGS13 表达增加，导致对鞘氨醇 1-磷酸的 Ca(2+) 动员减少。这些研究表明，p53 可能通过抑制 MC 和 B 细胞中 RGS13 的转录来调节免疫反应。
