Department of Surgery, Cell Biology Group, University of Maryland School of Medicine, MD 21201, USA, Baltimore Veterans Affairs Medical Center, Baltimore, MD 21201, USA, Department of Pathology, University of Maryland School of Medicine, MD 21201, USA and Laboratory of Genetics, National Institute on Aging-IRP, NIH, Baltimore, MD 21224, USA.
Nucleic Acids Res. 2013 Sep;41(16):7905-19. doi: 10.1093/nar/gkt565. Epub 2013 Jun 26.
Stromal interaction molecule 1 (Stim1) functions as a sensor of Ca2+ within stores and plays an essential role in the activation of store-operated Ca2+ entry (SOCE). Although lowering Stim1 levels reduces store-operated Ca2+ entry and inhibits intestinal epithelial repair after wounding, the mechanisms that control Stim1 expression remain unknown. Here, we show that cellular Stim1 abundance is controlled posttranscriptionally via factors that associate with 3'-untranslated region (3'-UTR) of stim1 mRNA. MicroRNA-195 (miR-195) and the RNA-binding protein HuR competed for association with the stim1 3'-UTR and regulated stim1 mRNA decay in opposite directions. Interaction of miR-195 with the stim1 3'-UTR destabilized stim1 mRNA, whereas the stability of stim1 mRNA increased with HuR association. Interestingly, ectopic miR-195 overexpression enhanced stim1 mRNA association with argonaute-containing complexes and increased the colocalization of tagged stim1 RNA with processing bodies (P-bodies); the translocation of stim1 mRNA was abolished by HuR overexpression. Moreover, decreased levels of Stim1 by miR-195 overexpression inhibited cell migration over the denuded area after wounding but was rescued by increasing HuR levels. In sum, Stim1 expression is controlled by two factors competing for influence on stim1 mRNA stability: the mRNA-stabilizing protein HuR and the decay-promoting miR-195.
基质相互作用分子 1（Stim1）作为细胞内钙库中的钙传感器发挥作用，在钙库操纵性钙内流（SOCE）的激活中起着至关重要的作用。尽管降低 Stim1 水平可减少钙库操纵性钙内流，并抑制创伤后的肠道上皮修复，但控制 Stim1 表达的机制仍不清楚。在这里，我们表明细胞内 Stim1 的丰度通过与 stim1 mRNA 3'-非翻译区（3'-UTR）结合的因子进行转录后控制。微小 RNA-195（miR-195）和 RNA 结合蛋白 HuR 竞争与 stim1 3'-UTR 结合，并以相反的方向调节 stim1 mRNA 的降解。miR-195 与 stim1 3'-UTR 的相互作用使 stim1 mRNA 不稳定，而 HuR 结合则增加 stim1 mRNA 的稳定性。有趣的是，外源性 miR-195 过表达增强了 stim1 mRNA 与含有 Argonaute 的复合物的结合，并增加了标记的 stim1 RNA 与处理体（P 体）的共定位；HuR 过表达可消除 stim1 mRNA 的易位。此外，miR-195 过表达降低 Stim1 水平可抑制创伤后裸区的细胞迁移，但通过增加 HuR 水平可挽救这一现象。总之，Stim1 的表达受两种竞争影响 stim1 mRNA 稳定性的因素控制：mRNA 稳定蛋白 HuR 和促进降解的 miR-195。
