Department of Orthopaedics, Washington University School of Medicine, St. Louis, MO, 63110, USA.
Shanghai Center for Bioinformation Technology & Shanghai Engineering Research Center of Pharmaceutical Translation, Shanghai Industrial Technology Institute, 1278 Keyuan Road, Shanghai, 201203, China.
J Autoimmun. 2019 Jul;101:94-108. doi: 10.1016/j.jaut.2019.04.015. Epub 2019 Apr 22.
Store-operated calcium entry (SOCE) modulates cytosolic calcium in multiple cells. Endoplasmic reticulum (ER)-localized STIM1 and plasma membrane (PM)-localized ORAI1 are two main components of SOCE. STIM1:ORAI1 association requires STIM1 oligomerization, its re-distribution to ER-PM junctions, and puncta formation. However, little is known about the negative regulation of these steps to prevent calcium overload. Here, we identified Tmem178 as a negative modulator of STIM1 puncta formation in myeloid cells. Using site-directed mutagenesis, co-immunoprecipitation assays and FRET imaging, we determined that Tmem178:STIM1 association occurs via their transmembrane motifs. Mutants that increase Tmem178:STIM1 association reduce STIM1 puncta formation, SOCE activation, impair inflammatory cytokine production in macrophages and osteoclastogenesis. Mutants that reduce Tmem178:STIM1 association reverse these effects. Furthermore, exposure to plasma from arthritic patients decreases Tmem178 expression, enhances SOCE activation and cytoplasmic calcium. In conclusion, Tmem178 modulates the rate-limiting step of STIM1 puncta formation and therefore controls SOCE in inflammatory conditions.
钙库操纵性钙内流（SOCE）调节多种细胞的细胞浆钙。内质网（ER）定位的 STIM1 和质膜（PM）定位的 ORAI1 是 SOCE 的两个主要组成部分。STIM1:ORAI1 缔合需要 STIM1 寡聚化、其重新分布到 ER-PM 连接处和形成斑点。然而，对于这些步骤的负调控以防止钙过载知之甚少。在这里，我们鉴定了 Tmem178 作为髓系细胞中 STIM1 斑点形成的负调节剂。通过定点突变、共免疫沉淀测定和 FRET 成像，我们确定 Tmem178:STIM1 缔合通过它们的跨膜基序发生。增加 Tmem178:STIM1 缔合的突变体减少 STIM1 斑点形成、SOCE 激活、损害巨噬细胞中的炎症细胞因子产生和破骨细胞生成。减少 Tmem178:STIM1 缔合的突变体逆转这些效应。此外，来自关节炎患者的血浆暴露降低 Tmem178 表达，增强 SOCE 激活和细胞质钙。总之，Tmem178 调节 STIM1 斑点形成的限速步骤，因此在炎症条件下控制 SOCE。
