Williams L M, Ridley A J
Ludwig Institute for Cancer Research, Royal Free and University College Medical School, London, United Kingdom.
J Immunol. 2000 Feb 15;164(4):2028-36. doi: 10.4049/jimmunol.164.4.2028.
The bacterial endotoxin LPS is a potent stimulator of monocyte and macrophage activation and induces adhesion of monocytes. Morphological changes in response to LPS have not been characterized in detail, however, nor have the signaling pathways mediating LPS-induced adhesion been elucidated. We have found that LPS rapidly induced adhesion and spreading of peripheral blood monocytes, and that this was inhibited by the Src family kinase inhibitor PP1 and the phosphatidylinositide 3-kinase inhibitor LY294002. LPS also stimulated actin reorganization, leading to the formation of filopodia, lamellipodia, and membrane ruffles in Bac1 mouse macrophages. Proline-rich tyrosine kinase 2 (Pyk2), a tyrosine kinase related to focal adhesion kinase, and paxillin, a cytoskeletal protein that interacts with Pyk2, were both tyrosine phosphorylated in response to LPS in monocytes and macrophages. Both tyrosine phosphorylation events were inhibited by PP1 and LY294002. Adhesion also stimulated tyrosine phosphorylation of Pyk2 and paxillin in monocytes, and this was further enhanced by LPS. Finally, Pyk2 and paxillin colocalized within membrane ruffles in LPS-stimulated cells. These results indicate that LPS stimulation of monocytes and macrophages results in rapid morphological changes and suggest that Pyk2 and/or paxillin play a role in this response.
细菌内毒素脂多糖（LPS）是单核细胞和巨噬细胞激活的强效刺激物，并可诱导单核细胞黏附。然而，LPS引起的形态学变化尚未得到详细描述，介导LPS诱导黏附的信号通路也未阐明。我们发现，LPS能迅速诱导外周血单核细胞黏附与铺展，而Src家族激酶抑制剂PP1和磷脂酰肌醇3激酶抑制剂LY294002可抑制这种现象。LPS还能刺激肌动蛋白重排，导致Bac1小鼠巨噬细胞中丝状伪足、片状伪足和膜皱褶的形成。富含脯氨酸的酪氨酸激酶2（Pyk2）是一种与黏着斑激酶相关的酪氨酸激酶，桩蛋白是一种与Pyk2相互作用的细胞骨架蛋白，在单核细胞和巨噬细胞中，它们在LPS刺激下均发生酪氨酸磷酸化。这两种酪氨酸磷酸化事件均被PP1和LY294002抑制。黏附也能刺激单核细胞中Pyk2和桩蛋白的酪氨酸磷酸化，而LPS可进一步增强这种作用。最后，在LPS刺激的细胞中，Pyk2和桩蛋白在膜皱褶内共定位。这些结果表明，LPS刺激单核细胞和巨噬细胞会导致快速的形态学变化，并提示Pyk2和/或桩蛋白在这一反应中发挥作用。
