Department of Microbiology and Immunology, Indiana University School of Medicine, Indianapolis, IN 46202, USA.
J Immunol. 2012 Aug 15;189(4):1689-98. doi: 10.4049/jimmunol.1101484. Epub 2012 Jul 13.
CD1d molecules are MHC class I-like molecules that present lipid Ags to NKT cells. Although we have previously shown that several different cell signaling molecules can play a role in the control of Ag presentation by CD1d, a defined mechanism by which a cell signaling pathway regulates CD1d function has been unclear. In the current study, we have found that the Rho kinases, Rho-associated, coiled-coil containing protein kinase (ROCK)1 and ROCK2, negatively regulate both human and mouse CD1d-mediated Ag presentation. Inhibition of ROCK pharmacologically, through specific ROCK1 and ROCK2 short hairpin RNA, or by using dendritic cells generated from ROCK1-deficient mice all resulted in enhanced CD1d-mediated Ag presentation compared with controls. ROCK regulates the actin cytoskeleton by phosphorylating LIM kinase, which, in turn, phosphorylates cofilin, prohibiting actin fiber depolymerization. Treatment of APCs with the actin filament depolymerizing agent, cytochalasin D, as well as knockdown of LIM kinase by short hairpin RNA, resulted in enhanced Ag presentation to NKT cells by CD1d, consistent with our ROCK inhibition data. Therefore, our overall results reveal a model whereby CD1d-mediated Ag presentation is negatively regulated by ROCK via its effects on the actin cytoskeleton.
CD1d 分子是 MHC 类 I 样分子，可将脂质抗原呈递给 NKT 细胞。尽管我们之前已经表明，几种不同的细胞信号分子可以在 CD1d 介导的抗原呈递中发挥作用，但细胞信号通路调节 CD1d 功能的明确机制尚不清楚。在本研究中，我们发现 Rho 激酶（Rho-associated, coiled-coil containing protein kinase，ROCK）1 和 ROCK2 负调控人源和鼠源 CD1d 介导的抗原呈递。通过特定的 ROCK1 和 ROCK2 短发夹 RNA 进行 ROCK 的药理学抑制，或使用源自 ROCK1 缺陷型小鼠的树突状细胞，均与对照组相比，增强了 CD1d 介导的抗原呈递。ROCK 通过磷酸化 LIM 激酶来调节肌动蛋白细胞骨架，而 LIM 激酶又磷酸化原肌球蛋白，从而阻止肌动蛋白纤维解聚。用细胞松弛素 D 处理 APCs（即肌动蛋白丝解聚剂），以及通过短发夹 RNA 敲低 LIM 激酶，均导致 CD1d 介导的抗原呈递给 NKT 细胞增强，与我们的 ROCK 抑制数据一致。因此，我们的总体结果揭示了一个模型，即 CD1d 介导的抗原呈递受 ROCK 通过其对肌动蛋白细胞骨架的影响负调控。
