miR-224对Rac1/Cdc42通路介导的类风湿关节炎成纤维样滑膜细胞迁移和侵袭的调控

Fibroblast-like synoviocytes (FLS) are characterized by enhancing migration and invasion, which contribute to the pathogenesis of rheumatoid arthritis (RA). Recent studies implied that miR-224 regulates migration and invasion in some cancer cells, where Rho GTPases are possibly involved. Our previous researches indicated that Rho GTPases are the major components in the regulation of migration and invasion in RA FLS. Expression of miR-224 decreased significantly in RA FLS, and overexpression of miR-224 by miRNA mimics inhibited migration and invasion in RA FLS. Based on the previous findings, we will further investigate the role and possible mechanism of miR-224 in the regulation of migration and invasion in RA FLS through activating Rho GTPases. We will also determine the in vivo effect of miR-224 in modulating Rho GTPases expression as well as improving pathological changes in RA by severe combined immunodeficiency (SCID) model and collagen-induced arthritis (CIA) model. Our research will provide evidence for the role of miR-224 in joint destruction, and will help find new targets for RA treatment.

成纤维样滑膜细胞（FLS）异常迁移和侵袭是类风湿关节炎（RA）滑膜病变持续进展和关节破坏的关键环节，其调控机制尚未完全清楚。近年发现miR-224可能通过影响Rho蛋白家族的Cdc42参与调控肿瘤细胞迁移和侵袭，但miR-224是否参与RA的关节滑膜病变仍不清楚。我们前期研究发现，Rho蛋白在调控RA FLS迁移和侵袭方面起重要作用，miR-224在RA滑膜中表达明显下降，上调miR-224表达能显著抑制RA FLS迁移和侵袭。因此，基于我们以往的工作基础，本课题拟通过研究miR-224对RA FLS迁移和侵袭的调节作用及其是否通过Rho蛋白（Rac1/Cdc42）信号通路介导；并利用严重免疫缺陷小鼠和胶原诱导关节炎模型，观察体内调节miR-224表达对RA FLS迁移、侵袭及关节损害的改善作用，旨在探讨miR-224对RA滑膜侵袭和关节破坏的调控作用，为寻找治疗RA的新靶点提供新的思路。

成纤维样滑膜细胞（FLS）是RA滑膜的基本成分，其活性增加，迁移、侵袭能力增强是RA关节病变的重要环节之一。本课题利用分子生物学技术，发现在RA FLS中，miR-224的表达较正常人或骨关节炎（OA）FLS明显下降。在炎症因子TNF-α或LPS的刺激下，miR-224的表达进一步下降，相反，治疗RA的药物如地塞米松或甲氨蝶呤能促进RA FLS中miR-224的表达。采用miRNA mimics或inhibitors过表达或抑制RA FLS或正常人FLS中miR-224的表达，发现miR-224能抑制RA FLS的迁移、侵袭和骨架蛋白重排。此外，miR-224能抑制MMP-1和MMP-3的表达。机制研究发现，miR-224与Rho蛋白家族成员Rac1及Cdc42的3’UTR均有结合位点。miR-224可抑制Rac1及Cdc42的蛋白水平，从而抑制细胞的迁移、侵袭能力。上述研究提示，miR-224参与了RA FLS活化、迁移、侵袭的调控过程，通过干预miR-224可能可以抑制RA的关节破坏。