Toll-like receptor 4-mediated cAMP production up-regulates B-cell activating factor expression in Raw264.7 macrophages
Toll-like receptor 4-mediated cAMP production up-regulates B-cell activating factor expression in Raw264.7 macrophages
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DOI：
10.1016/j.yexcr.2011.07.003
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发表时间：
2011-10-15
影响因子：
3.7
通讯作者：
Lee, Mi-Hee
中科院分区：
文献类型：
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作者：
Moon, Eun-Yi;Lee, Yu-Sun;Lee, Mi-Hee
B细胞活化因子（BAFF）在成熟B细胞的生成和维持中起作用。脂多糖（LPS）通过激活Toll样受体4（TLR 4）依赖的信号转导增加BAFF表达。在这里，我们研究了通过在Raw 264.7小鼠巨噬细胞中产生cAMP对小鼠BAFF（mBAFF）表达的作用机制。通过用cAMP类似物二丁酰-cAMP（其是蛋白激酶A（PKA）的激活剂，cAMP效应蛋白）处理，mBAFF表达增加。PKA活化通过丝氨酸133（S133）上cAMP-反应元件结合蛋白（CREB）的磷酸化来测量。cAMP的产生和CREB（S133）磷酸化增加LPS刺激。虽然mBAFF启动子活性通过与pS 6-RSV-CREB共转染而增强，但其被siRNA-CREB降低。PKA抑制剂H-89降低对照和LPS刺激的巨噬细胞中CREB（S133）磷酸化和mBAFF表达。另一种主要的cAMP效应蛋白是cAMP响应性鸟嘌呤核苷酸交换因子（Epac），一种Rap GDP交换因子。通过测量Rap 1的活化来判断，用Epac活化剂8-（4-氯-苯硫基）-2 ′-O-甲基腺苷-3 ′，5 ′-环一磷酸（CPT）处理可活化Epac。CPT处理增加了mBAFF表达的基础水平。LPS刺激的mBAFF表达也通过与CPT共处理而略微增强。此外，二丁酰-cAMP和CPT增强骨髓源性巨噬细胞（BMDM）中的mBAFF表达。这些数据表明，PKA和cAMP/Epac 1/Rapt通路的激活可能是基础mBAFF表达所必需的，并且在TLR 4诱导的mBAFF表达中被上调。皇冠版权所有（C）2011由爱思唯尔公司出版。All rights reserved.
B-cell activating factor (BAFF) plays a role in the generation and the maintenance of mature B cells. Lipopolysaccharide (LPS) increased BAFF expression through the activation of toll-like receptor 4 (TLR4)-dependent signal transduction. Here, we investigated the mechanism of action on mouse BAFF (mBAFF) expression by cAMP production in Raw264.7 mouse macrophages. mBAFF expression was increased by the treatment with a cAMP analogue, dibutyryl-cAMP which is the activator of protein kinase A (PKA), cAMP effector protein. PKA activation was measured by the phosphorylation of cAMP-response element binding protein (CREB) on serine 133 (S133). cAMP production and CREB (S133) phosphorylation were augmented by LPS-stimulation. While mBAFF promoter activity was enhanced by the co-transfection with pS6-RSV-CREB, it was reduced by siRNA-CREB. PKA inhibitor, H-89, reduced CREB (S133) phosphorylation and mBAFF expression in control and LPS-stimulated macrophages. Another principal cAMP effector protein is cAMP-responsive guanine nucleotide exchange factor (Epac), a Rap GDP exchange factor. Epac was activated by the treatment with 8-(4-chloro-phenylthio)-2'-O-methyladenosine-3',5'-cyclic monophosphate (CPT), Epac activator, as judged by the measurement of Rap1 activation. Basal level of mBAFF expression was increased by CPT treatment. LPS-stimulated mBAFF expression was also slightly enhanced by co-treatment with CPT. In addition, dibutyryl-cAMP and CPT enhanced mBAFF expression in bone marrow-derived macrophages (BMDM). With these data, it suggests that the activation of PKA and cAMP/Epac1/Rapt pathways could be required for basal mBAFF expression, as well as being up-regulated in the TLR4-induced mBAFF expression. Crown Copyright (C) 2011 Published by Elsevier Inc. All rights reserved.