p38β Mitogen-Activated Protein Kinase Signaling Mediates Exenatide-Stimulated Microglial β-Endorphin Expression
p38β Mitogen-Activated Protein Kinase Signaling Mediates Exenatide-Stimulated Microglial β-Endorphin Expression
复制标题
p38 β 丝裂原激活蛋白激酶信号介导艾塞那肽刺激的小胶质细胞 β-内啡肽表达
DOI：
10.1124/mol.116.107102
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发表时间：
2017-05-01
影响因子：
3.6
通讯作者：
Wang, Yong-Xiang
中科院分区：
文献类型：
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作者：
Wu, Hai-Yun;Mao, Xiao-Fang;Wang, Yong-Xiang
最近的研究发现，胰高血糖素样肽-1受体（GLP-1 Rs）的激活通过小胶质细胞β -内啡肽的表达介导神经保护和抗痛觉。本研究旨在探讨小胶质细胞-内啡肽的潜在信号机制。GLP-1Rs和β -内啡肽在小胶质细胞原代培养中共表达。GLP-1 R激动剂艾塞那肽浓度依赖性刺激β -内啡肽前体基因POMC和肽的小胶质表达，EC50值分别为4.1和7.5 nM。艾塞那肽还能显著提高培养的原代小胶质细胞内cAMP水平和p-蛋白激酶A （PKA）、p-p38和p-cAMP反应元件结合蛋白（CREB）的表达。此外，艾塞那肽诱导的POMC小胶质细胞表达被特异性抑制腺苷酸环化酶和PKA、p38和CREB激活的试剂完全阻断。此外，使用短干扰RNA （siRNA）敲除p38 β（而不是p38 α）可消除艾塞那肽诱导的小胶质细胞p38磷酸化和POMC表达。相比之下，脂多糖增加了p38的小胶质细胞活化，p38 α的下调（而不是p38 β）部分抑制了促炎因子（包括肿瘤坏死因子α、白细胞介素-1 β和白细胞介素-6）的表达。艾塞那肽诱导的p38和CREB磷酸化也被PKA抑制剂和siRNA/p38 β完全阻断，但不被siRNA/p38 α阻断。7天鞘内注射siRNA/p38 β（而不是siRNA/p38 α）完全阻断艾塞那肽诱导的脊髓p38激活，β -内啡肽表达和机械性抗异痛，尽管siRNA/p38 β和siRNA/p38 α没有抗异痛作用。据我们所知，我们的研究结果首次显示了pka依赖性p38 β -丝裂原激活蛋白激酶/CREB信号级联与GLP-1R激动剂介导的小胶质细胞b-内啡肽表达之间的因果关系。p38 α和p38 β激活在炎症和伤害感觉中的不同作用也被强调。
Recent discoveries established that activation of glucagon-like peptide-1 receptors (GLP-1 Rs) mediates neuroprotection and antinociception through microglial beta-endorphin expression. This study aimed to explore the underlying signaling mechanisms of microglial beta-endorphin. GLP-1Rs and beta-endorphin were coexpressed in primary cultures of microglia. Treatment with the GLP-1 R agonist exenatide concentration-dependently stimulated microglial expression of the beta-endorphin precursor gene proopiomelanocortin (POMC) and peptides, with EC50 values of 4.1 and 7.5 nM, respectively. Exenatide also significantly increased intracellular cAMP levels and expression of p-protein kinase A (PKA), p-p38, and p-cAMP response element binding protein (CREB) in cultured primary microglia. Furthermore, exenatide-induced microglial expression of POMC was completely blocked by reagents that specifically inhibit adenylyl cyclase and activation of PKA, p38, and CREB. In addition, knockdown of p38 beta (but not p38 alpha) using short interfering RNA (siRNA) eliminated exenatide-induced microglial p38 phosphorylation and POMC expression. In contrast, lipopolysaccharide increased microglial activation of p38, and knockdown of p38 alpha (but not p38 beta) partially suppressed expression of proinflammatory factors (including tumor necrosis factor-alpha, interleukin-1 beta, and interleukin-6). Exenatide-induced phosphorylation of p38 and CREB was also totally blocked by the PKA inhibitor and siRNA/p38 beta, but not by siRNA/p38 alpha. Seven-day intrathecal injections of siRNA/p38 beta (but not siRNA/p38 alpha) completely blocked exenatide-induced spinal p38 activation, beta-endorphin expression, and mechanical antiallodynia in rats with established neuropathy, although siRNA/p38 beta and siRNA/p38 alpha were not antiallodynic. To our knowledge, our results are the first to show a causal relationship between the PKA-dependent p38 beta mitogen-activated protein kinase/CREB signal cascade and GLP-1R agonism-mediated microglial b-endorphin expression. The differential role of p38 alpha and p38 beta activation in inflammation and nociception was also highlighted.