Kim Seon Sook, Lee Eun Hye, Lee Kooyeon, Jo Su-Hyun, Seo Su Ryeon
Department of Molecular Bioscience, College of Biomedical Science, Institute of Bioscience & Biotechnology, Kangwon National University, Chuncheon 200-701, Republic of Korea.
Department of Bio-Health Technology, College of Biomedical Science, Institute of Bioscience & Biotechnology, Kangwon National University, Chuncheon 200-701, Republic of Korea.
Biochem Biophys Res Commun. 2015 Apr 17;459(4):604-9. doi: 10.1016/j.bbrc.2015.02.155. Epub 2015 Mar 7.
Calcineurin is a calcium/calmodulin-dependent phosphatase that has been implicated in T cell activation through the induction of nuclear factors of activated T cells (NFAT). We have previously suggested that endogenous regulator of calcineurin (RCAN1, also known as DSCR1) is targeted by protein kinase A (PKA) for the control of calcineurin activity. In the present study, we characterized the PKA-mediated phosphorylation site in RCAN1 by mass spectrometric analysis and revealed that PKA directly phosphorylated RCAN1 at the Ser 93. PKA-induced phosphorylation and the increase in the half-life of the RCAN1 protein were prevented by the substitution of Ser 93 with Ala (S93A). Furthermore, the PKA-mediated phosphorylation of RCAN1 at Ser 93 potentiated the inhibition of calcineurin-dependent pro-inflammatory cytokine gene expression by RCAN1. Our results suggest the presence of a novel phosphorylation site in RCAN1 and that its phosphorylation influences calcineurin-dependent inflammatory target gene expression.
钙调神经磷酸酶是一种钙/钙调蛋白依赖性磷酸酶，通过诱导活化T细胞核因子（NFAT）参与T细胞活化。我们之前曾提出，钙调神经磷酸酶的内源性调节因子（RCAN1，也称为DSCR1）是蛋白激酶A（PKA）的作用靶点，用于控制钙调神经磷酸酶的活性。在本研究中，我们通过质谱分析对RCAN1中PKA介导的磷酸化位点进行了表征，发现PKA直接在Ser 93位点磷酸化RCAN1。用丙氨酸替代Ser 93（S93A）可阻止PKA诱导的磷酸化以及RCAN1蛋白半衰期的延长。此外，PKA介导的RCAN1在Ser 93位点的磷酸化增强了RCAN1对钙调神经磷酸酶依赖性促炎细胞因子基因表达的抑制作用。我们的结果表明RCAN1中存在一个新的磷酸化位点，其磷酸化影响钙调神经磷酸酶依赖性炎症靶基因的表达。
