Tanabe Kumiko, Kozawa Osamu, Iida Hiroki
Department of Anesthesiology and Pain Medicine, Gifu University Graduate School of Medicine, Gifu 501-1194, Japan.
Department of Pharmacology, Gifu University Graduate School of Medicine, Gifu 501-1194, Japan.
Cell Signal. 2016 Jan;28(1):19-24. doi: 10.1016/j.cellsig.2015.10.009. Epub 2015 Oct 23.
We previously reported that interleukin (IL)-1β induces IL-6 synthesis via activation of the IκB/NFκB pathway, p38 mitogen-activated protein (MAP) kinase, stress-activated protein kinase/c-Jun N-terminal kinase (SAPK/JNK), and signal transducer and activator of transcription (STAT)3, but not p44/p42 MAP kinase in rat glioma cell line, C6 cells and that cAMP enhances the IL-6 synthesis. However, the details behind enhancement of IL-1β-induced IL-6 synthesis by cAMP remain to be elucidated. In the present study, we investigated the exact mechanism of cAMP underlying the amplification of IL-1β-induced IL-6 synthesis in C6 cells. 8-Bromo cAMP significantly enhanced IL-1β-induced STAT3 phosphorylation without affecting phosphorylation of IκB, p38 MAP kinase or SAPK/JNK. In addition, we found that forskolin, a direct activator of adenylyl cyclase, significantly enhanced IL-1β-induced STAT3 phosphorylation. Janus family of tyrosine kinase (JAK) inhibitor I markedly suppressed the amplification by 8-bromo cAMP of IL-1β-induced IL-6 release. IL-1β induced JAK2 phosphorylation, and FLLL32, a specific JAK2 inhibitor, significantly reduced IL-1β-stimulated IL-6 release. 4-Cyano-3-methylisoquinoline, an inhibitor of protein kinase A (PKA), significantly attenuated the enhancing effect of 8-bromo cAMP on IL-1β-induced STAT3 phosphorylation. 8-Bromo cAMP markedly induced JAK2 phosphorylation. PKA siRNA transfection reduced enhancement of IL-1β-induced IL-6 release by 8-bromo cAMP. In conclusion, our results strongly suggest that the adenylyl cyclase/cAMP/PKA pathway upregulates IL-1β-induced IL-6 synthesis through enhancement of the JAK2/STAT3 pathway in C6 glioma cells.
我们之前报道过，白细胞介素（IL）-1β通过激活IκB/NFκB途径、p38丝裂原活化蛋白（MAP）激酶、应激激活蛋白激酶/c-Jun氨基末端激酶（SAPK/JNK）以及信号转导和转录激活因子（STAT）3来诱导IL-6的合成，但在大鼠胶质瘤细胞系C6细胞中不通过p44/p42 MAP激酶诱导，并且环磷酸腺苷（cAMP）可增强IL-6的合成。然而，cAMP增强IL-1β诱导的IL-6合成背后的具体细节仍有待阐明。在本研究中，我们探究了cAMP在C6细胞中放大IL-1β诱导的IL-6合成的具体机制。8-溴环磷酸腺苷显著增强了IL-1β诱导的STAT3磷酸化，而不影响IκB、p38 MAP激酶或SAPK/JNK的磷酸化。此外，我们发现腺苷酸环化酶的直接激活剂福斯可林显著增强了IL-1β诱导的STAT3磷酸化。酪氨酸激酶（JAK）家族抑制剂I显著抑制了8-溴环磷酸腺苷对IL-1β诱导的IL-6释放的放大作用。IL-1β诱导JAK2磷酸化，而特异性JAK2抑制剂FLLL32显著降低了IL-1β刺激的IL-6释放。蛋白激酶A（PKA）抑制剂4-氰基-3-甲基异喹啉显著减弱了8-溴环磷酸腺苷对IL-1β诱导的STAT3磷酸化的增强作用。8-溴环磷酸腺苷显著诱导JAK2磷酸化。PKA小干扰RNA转染降低了8-溴环磷酸腺苷对IL-1β诱导的IL-6释放的增强作用。总之，我们的结果强烈表明，腺苷酸环化酶/cAMP/PKA途径通过增强C6胶质瘤细胞中的JAK2/STAT3途径上调IL-1β诱导的IL-6合成。
