Tespa1 protein is phosphorylated in response to store-operated calcium entry
Tespa1 protein is phosphorylated in response to store-operated calcium entry
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DOI：
10.1016/j.bbrc.2013.02.128
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发表时间：
2013-04-26
影响因子：
3.1
通讯作者：
Shirasawa, Senji
中科院分区：
文献类型：
--
作者：
Fujimoto, Takahiro;Matsuzaki, Hiroshi;Shirasawa, Senji
我们之前报道过，淋巴细胞中表达的 Tespa1（胸腺细胞表达的正选择相关基因 1）蛋白与 IP3R（肌醇 1,4,5-三磷酸受体）（一种跨越内质网 (ER) 膜的 Ca2+ 通道蛋白）发生物理相互作用。然而，Tespa1 蛋白的生化特征仍然未知。在这项研究中，我们发现 Tespa1 蛋白在胸腺细胞中胞内 Ca2+ 增加时发生翻译后修饰。通过使用各种抑制剂的分析，发现钙库操纵的Ca2+进入（SOCE）是T细胞受体（TCR）刺激诱导的Tespa1蛋白修饰的重要因素。值得注意的是，Ca2+依赖性Tespa1蛋白修饰通过体外蛋白磷酸酶处理得以恢复，表明这种修饰是由于磷酸化造成的。此外，我们检查了 Tespa1 蛋白的 Ca2+ 依赖性磷酸化是否会影响 Tespa1 和 IP3R 蛋白之间的物理关联，结果表明，无论 Tespa1 磷酸化是否存在，这些蛋白的物理关联都得以维持。此外，与 Tespa1 具有显着氨基酸序列同源性的 KRAP 蛋白在 HCT116 人结肠癌细胞和 HEK293 人胚胎肾细胞中也因细胞内 Ca2+ 增加而被翻译后磷酸化，这表明共同的信号传导机制可能有助于 Tespa1 和 KRAP 在不同细胞过程中的分子修饰。所有这些结果表明Tespa1有一种新的分子修饰以及SOCE影响Tespa1-IP3R分子复合物的调控途径的存在。 (C) 2013 Elsevier Inc. 保留所有权利。
We previously reported that Tespa1 (thymocyte-expressed, positive selection-associated gene 1) protein expressed in lymphocytes physically interacts with IP3R (Inositol 1,4,5-trisphosphate receptor), a Ca2+ channel protein spanning endoplasmic reticulum (ER) membrane. However, the biochemical characterization of Tespa1 protein remains unknown. In this study, we have found that Tespa1 protein was posttranslationally modified upon intracellular Ca2+ increase in thymocytes. Through the analyses using various inhibitors, store-operated Ca2+ entry (SOCE) was found to be an essential factor for the Tespa1 protein modification induced by T cell receptor (TCR)-stimulation. Remarkably, the Ca2+-dependent Tespa1 protein modification was restored by in vitro protein phosphatase treatment, indicating that this modification was due to phosphorylation. Moreover, we examined whether Ca2+-dependent phosphorylation of Tespa1 protein would affect the physical association between Tespa1 and IP3R proteins, revealing that physical association of these proteins is maintained regardless of the presence or absence of phosphorylation of Tespa1. In addition, KRAP protein which represents substantial amino acid sequence homology to Tespa1 was also posttranslationally phosphorylated by intracellular Ca2+ increase in HCT116 human colon cancer cells and HEK293 human embryonic kidney cells, suggesting that common signaling mechanism(s) may contribute to the molecular modification of Tespa1 and KRAP in different cellular processes. All these results suggested a novel molecular modification of Tespa1 and the existence of the regulatory pathway that SOCE affects the Tespa1-IP3R molecular complex. (C) 2013 Elsevier Inc. All rights reserved.