Diminishment of α-MSH anti-inflammatory activity in MC1r siRNA-transfected RAW264.7 macrophages
Diminishment of α-MSH anti-inflammatory activity in MC1r siRNA-transfected RAW264.7 macrophages
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DOI：
10.1189/jlb.0707463
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发表时间：
2008-07-01
影响因子：
5.5
通讯作者：
Taylor, Andrew W.
中科院分区：
文献类型：
--
作者：
Li, Dayu;Taylor, Andrew W.
神经肽α-黑素细胞刺激激素（α-MSH）是巨噬细胞介导的炎症的有力抑制剂，巨噬细胞表达至少两种受体，即结合α-MSH的黑皮质素1和3受体（MC 1 r和MC 3r）。尽管α-MSH在巨噬细胞中的抗炎活性已得到充分证实，但α-MSH在巨噬细胞中的活性机制尚不清楚。本研究旨在探讨巨噬细胞表达的MCr中哪些与α-MSH对LPS刺激的巨噬细胞的免疫抑制活性相关。为了解决这个问题，我们用MC 1 r小干扰（si）RNA转染RAW264.7巨噬细胞，该RNA特异性靶向小鼠MC 1 r mRNA。转染后24 h和48 h MC 1 r mRNA表达分别下降82%和67%。有一个显着的损失α-MSH抑制NO的产生和TNF-α的生产MC 1 r siRNA转染的巨噬细胞刺激LPS。α-MSH对LPS刺激的NF-κ B和p38磷酸化的细胞内活化的抑制作用同样减弱。此外，通过siRNA转染减少MC 1 r的表达对MC 3r在巨噬细胞中的表达和功能没有影响。这些发现表明，α-MSH抑制LPS诱导的巨噬细胞炎症活性需要MC 1 r的表达。结果表明，尽管所有的MCr都是G偶联蛋白，但它们在巨噬细胞中可能不一定通过相同的细胞内途径发挥作用。
The neuropeptide alpha-melanocyte-stimulating hormone (alpha-MSH) is a powerful suppressor of inflammation mediated by macrophages, which express at least two receptors, melanocortin 1 and 3 receptors (MC1r and MC3r) that bind alpha-MSH. Albeit, the anti-inflammatory activity of alpha-MSH has been well documented in macrophages, the mechanisms of alpha-MSH activity in macrophages are not clearly understood. This study is to investigate which of the MCr expressed on macrophages is associated with the immunosuppressive activities of alpha-MSH on LPS-stimulated macrophages. To address this question, we transfected RAW264.7 macrophage cells with MC1r small interfering (si) RNA, which specifically targets mouse MC1r mRNA. The diminution of MC1r mRNA expression was 82% at 24 h and 67% at 48 h after transfection. There was a significant loss in alpha-MSH suppression of NO generation and TNF-alpha production by MC1r siRNA-transfected macrophages stimulated with LPS. There was an equally diminished alpha-MSH suppression of LPS-stimulated intracellular activation of NF-kappa B and p38 phosphorylation. In addition, the diminishment of MC1r expression by siRNA transfection had no influence on MC3r expression and function in the macrophages. These findings demonstrate that alpha-MSH suppression of LPS-induced inflammatory activity in macrophages requires expression of MC1r. The results imply that although all of the MCr are G-coupled proteins, they may not necessarily function through the same intracellular pathways in macrophages.