Andrographolide Enhances Nuclear Factor-κB Subunit p65 Ser536 Dephosphorylation through Activation of Protein Phosphatase 2A in Vascular Smooth Muscle Cells
Andrographolide Enhances Nuclear Factor-κB Subunit p65 Ser536 Dephosphorylation through Activation of Protein Phosphatase 2A in Vascular Smooth Muscle Cells
复制标题
DOI：
10.1074/jbc.m110.123968
复制
发表时间：
2011-02-25
影响因子：
4.8
通讯作者：
Sheu, Joen R.
中科院分区：
文献类型：
--
作者：
Hsieh, Cheng Y.;Hsu, Ming J.;Sheu, Joen R.
最近的研究表明，转录因子核因子（NF）-κ B抑制可能有助于穿心莲，穿心莲属植物的丰富组成部分的保护性抗炎作用。然而，穿心莲内酯抑制NF-κ B信号传导的确切机制仍不清楚。因此，我们研究了穿心莲内酯抑制大鼠血管平滑肌细胞（VSMCs）中NF-κ B B信号传导的机制，这些细胞暴露于促炎刺激、LPS和IFN-γ。穿心莲内酯可抑制LPS/IFN-γ诱导的大鼠VSMCs诱导型一氧化氮合酶和基质金属蛋白酶9的表达。穿心莲内酯还抑制LPS/IFN-γ诱导的p65核转位、DNA结合活性、p65 Ser（536）磷酸化和NF-κ B报告基因活性。然而，IKK磷酸化和下游抑制性κ B α磷酸化和降解并没有被穿心莲内酯在LPS/IFN-γ刺激的VSMCs中的存在所改变。中性鞘磷脂酶和蛋白磷酸酶2A（PP 2A）的选择性抑制可以阻止这些穿心莲内酯的抑制作用。此外，在大鼠颈动脉损伤模型中，穿心莲内酯可增加VSMCs中神经酰胺的形成和PP 2A活性，并抑制新生内膜的形成。这些结果表明，穿心莲内酯引起中性鞘磷脂酶介导的神经酰胺的形成和PP 2A活化，使p65 Ser（536）去磷酸化，导致NF-κ B失活，随后在LPS和IFN-γ刺激的大鼠VSMC中诱导型一氧化氮合酶下调。
Recent studies have demonstrated that transcription factor nuclear factor (NF)-kappa B inhibition may contribute to the protective anti-inflammatory actions of andrographolide, an abundant component of plants of the genus Andrographis. However, the precise mechanism by which andrographolide inhibits NF-kappa B signaling remains unclear. We thus investigated the mechanism involved in andrographolide suppression of NF-kappa B signaling in rat vascular smooth muscle cells (VSMCs) exposed to proinflammatory stimuli, LPS, and IFN-gamma. Andrographolide was shown to suppress LPS/IFN-gamma-induced inducible nitric-oxide synthase and matrix metalloprotease 9 expression in rat VSMCs. Andrographolide also inhibited LPS/IFN-gamma-induced p65 nuclear translocation, DNA binding activity, p65 Ser(536) phosphorylation, and NF-kappa B reporter activity. However, IKK phosphorylation and downstream inhibitory kappa B alpha phosphorylation and degradation were not altered by the presence of andrographolide in LPS/IFN-gamma-stimulated VSMCs. These andrographolide inhibitory actions could be prevented by selective inhibition of neutral sphingomyelinase and protein phosphatase 2A (PP2A). Furthermore, andrographolide was demonstrated to increase ceramide formation and PP2A activity in VSMCs and to inhibit neointimal formation in rat carotid injury models. These results suggest that andrographolide caused neutral sphingomyelinase-mediated ceramide formation and PP2A activation to dephosphorylate p65 Ser(536), leading to NF-kappa B inactivation and subsequent inducible nitric-oxide synthase down-regulation in rat VSMCs stimulated by LPS and IFN-gamma.