Decreased Expression of Serine/Arginine-Rich Splicing Factor 1 in T Cells From Patients With Active Systemic Lupus Erythematosus Accounts for Reduced Expression of RasGRP1 and DNA Methyltransferase 1
Decreased Expression of Serine/Arginine-Rich Splicing Factor 1 in T Cells From Patients With Active Systemic Lupus Erythematosus Accounts for Reduced Expression of RasGRP1 and DNA Methyltransferase 1
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DOI：
10.1002/art.40585
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发表时间：
2018-12-01
影响因子：
13.3
通讯作者：
Atsumi, Tatsuya
中科院分区：
文献类型：
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作者：
Kono, Michihiro;Kurita, Takashi;Atsumi, Tatsuya
目的系统性红斑狼疮(SLE)患者的T细胞表达RAS的鸟核苷酸交换因子RASGRP1蛋白水平降低，缺失外显子11的选择性剪接形式(AS)转录增加。富含丝氨酸/精氨酸的剪接因子1(SRSF1)与前信使RNA(Pre-mRNAs)结合，调节SLE T细胞中包括CD3 Zeta在内的多种基因。本研究旨在探讨SRSF1对系统性红斑狼疮患者T细胞中RASGRP1表达的影响。定量聚合酶链式反应检测SRSF1、野生型(WT)RASGRP1和DNA甲基转移酶1(DNMT1)的表达水平。用寡核苷酸-蛋白质下拉实验检测SRSF1与RASGRP1基因第11外显子的直接结合。结果SLE患者T细胞SRSF1表达水平明显低于正常人，且与疾病活动性呈负相关，与RASGRP1-WT、DNMT1表达水平呈正相关。SRSF1直接与RASGRP1基因第11外显子结合。人T细胞中SRSF1的沉默导致RASGRP1-AS/RASGRP1-WT比值升高，RASGRP1蛋白水平下降，而SRSF1在SLE T细胞中的过表达导致RASGRP1的恢复，进而诱导DNMT1/IL-2的表达。我们的发现进一步证明，选择性剪接通过控制多个基因的表达，在SLE患者异常的T细胞功能中发挥核心作用。
Objective T cells from systemic lupus erythematosus (SLE) patients have reduced protein levels of RasGRP1, a guanine nucleotide exchange factor for Ras, and increased transcript of alternatively spliced (AS) forms lacking exon 11. Serine/arginine-rich splicing factor 1 (SRSF1) binds pre-messenger RNA (pre-mRNA) to regulate AS forms of several genes, including CD3 zeta in SLE T cells. This study was undertaken to assess whether SRSF1 controls the expression of RasGRP1 in T cells from patients with SLE.Methods We studied T cells from 45 SLE patients and 18 healthy subjects. Expression levels of SRSF1, wild-type (WT) RasGRP1, and DNA methyltransferase 1 (DNMT1) were assessed by quantitative polymerase chain reaction. Direct binding of SRSF1 to exon 11 of RasGRP1 mRNA was evaluated with an oligonucleotide-protein pulldown assay. Healthy T cells and SLE T cells were treated with SRSF1-specific small interfering RNA or SRSF1 expression vector, respectively, and then evaluated for mRNA/protein expression.Results SRSF1 expression levels were significantly lower in T cells from SLE patients compared to those from healthy subjects, and correlated inversely with disease activity and positively with levels of RasGRP1-WT and DNMT1. SRSF1 bound directly to exon 11 of RasGRP1 mRNA. Silencing of SRSF1 in human T cells led to increased ratios of RasGRP1-AS to RasGRP1-WT and decreased levels of RasGRP1 protein, whereas overexpression of SRSF1 in SLE T cells caused recovery of RasGRP1, which in turn induced DNMT1/interleukin-2 expression.Conclusion SRSF1 controls the alternative splicing of RasGRP1 and subsequent protein expression. Our findings extend evidence that alternative splicing plays a central role in the aberrant T cell function in patients with SLE by controlling the expression of multiple genes.