Lipopolysaccharide-induced sensitization of adenylyl cyclase activity in murine macrophages
Lipopolysaccharide-induced sensitization of adenylyl cyclase activity in murine macrophages
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DOI：
10.1152/ajpcell.00171.2005
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发表时间：
2006-01-01
影响因子：
5.5
通讯作者：
Emala, CW
中科院分区：
文献类型：
--
作者：
Osawa, Y;Lee, HT;Emala, CW
已知LPS在脓毒症期间调节巨噬细胞应答，包括细胞因子释放、吞噬作用和增殖。尽管升高cAMP的kagents逆转LPS诱导的巨噬细胞功能，但LPS本身是否调节cAMP以及LPS诱导的增殖降低是否通过cAMP依赖性途径调节尚不清楚。在存在或不存在前列腺素信号传导、蛋白激酶、CaM、G（i）蛋白和NF-κ B易位或转录/翻译的抑制剂的情况下，用LPS处理小鼠巨噬细胞（RAW 264.7细胞）。测定LPS对CaMKII磷酸化和相关腺苷酸环化酶（AC）亚型表达的影响。LPS引起毛喉素刺激的AC活性的显著剂量（5 - 10，000 ng/ml）和时间（1 - 8 h）依赖性增加，其通过用SN 50（NF-κ B B抑制剂）、放线菌素D或放线菌酮预处理而被消除，表明该效应是通过NF-κ B依赖性转录和新蛋白质合成介导的。此外，LPS降低了CaMKII的磷酸化状态，并且用CaM拮抗剂预处理减弱了LPS诱导的AC敏化。LPS、cAMP或PKA活化各自独立地降低巨噬细胞增殖。然而，NF-κ B的抑制对LPS诱导的增殖减少没有影响，表明LPS诱导的巨噬细胞增殖减少可以通过PKA非依赖性信号传导途径进行。两者合计，这些发现表明，LPS诱导AC活性的敏化，通过增强CaM的刺激作用和减弱CaMK II对CaMK敏感的AC亚型的抑制作用。
LPS is known to modulate macrophage responses during sepsis, including cytokine release, phagocytosis, and proliferation. Although kagents that elevate cAMP reverse LPS-induced macrophage functions, whether LPS itself modulates cAMP and whether LPS-induced decreases in proliferation are modulated via a cAMP-dependent pathway are not known. Murine macrophages (RAW264.7 cells) were treated with LPS in the presence or absence of inhibitors of prostaglandin signaling, protein kinases, CaM, G(i) proteins, and NF-kappa B translocation or transcription/translation. LPS effects on CaMKII phosphorylation and the expression of relevant adenylyl cyclase (AC) isoforms were measured. LPS caused a significant dose (5 - 10,000 ng/ml)- and time ( 1 - 8 h)- dependent increase in forskolin-stimulated AC activity that was abrogated by pretreatment with SN50 (an NF-kappa B inhibitor), actinomycin D, or cycloheximide, indicating that the effect is mediated via NF-kappa B-dependent transcription and new protein synthesis. Furthermore, LPS decreased the phosphorylation state of CaMKII, and pretreatment with a CaM antagonist attenuated the LPS-induced sensitization of AC. LPS, cAMP, or PKA activation each independently decreased macrophage proliferation. However, inhibition of NF-kappa B had no effect on LPS-induced decreased proliferation, indicating that LPS-induced decreased macrophage proliferation can proceed via PKA-independent signaling pathways. Taken together, these findings indicate that LPS induces sensitization of AC activity by augmenting the stimulatory effect of CaM and attenuating the inhibitory effect of CaMKII on isoforms of AC that are CaMK sensitive.