Conditional Knockout of the RNA-Binding Protein HuR in CD4+ T Cells Reveals a Gene Dosage Effect on Cytokine Production
Conditional Knockout of the RNA-Binding Protein HuR in CD4+ T Cells Reveals a Gene Dosage Effect on Cytokine Production
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DOI：
10.2119/molmed.2013.00127
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发表时间：
2014-01-01
影响因子：
5.7
通讯作者：
Atasoy, Ulus
中科院分区：
文献类型：
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作者：
Gubin, Matthew M.;Techasintana, Patsharaporn;Atasoy, Ulus
RNA结合蛋白(RBPs)在体内调节T细胞分化和细胞因子产生的转录后机制尚不清楚。RBP Hur与不稳定的mRNAs结合，通常导致mRNA稳定性和/或翻译的增加。以前的工作表明，Hur与编码Th2转录因子反式T细胞特异性转录因子(GATA-3)和Th2细胞因子IL-4和IL-13的mRNAs结合，从而调节它们的表达。通过使用一种新的条件性Hur基因敲除(KO)小鼠，在激活的T细胞中缺失HUR，我们发现来自杂合HUR条件(OX40-CRE HUR(fl/+))KO小鼠的Th2极化细胞降低了GATA3，II4和II13mRNAs的稳态水平，而在蛋白质水平上几乎没有变化。令人惊讶的是，纯合子Hur条件性(OX40-Cre Hur(fl/fl))KO小鼠Th2极化的细胞通过不同的机制显示II2、II4和II13mRNA和蛋白质的增加。具体地说，II4在Hur KO T细胞中转录上调，而II2和II13mRNA的稳定性增加。此外，当使用标准的卵白蛋白过敏性呼吸道炎症模型时，HUR条件性KO小鼠表现出与野生型HUR水平的小鼠相似的强烈炎症反应。这些结果揭示了HUR对细胞因子的复杂差异转录后调节，其中基因剂量起着重要作用。这些发现可能对过敏和哮喘以及自身免疫性疾病和感染具有重要意义。
The posttranscriptional mechanisms by which RNA binding proteins (RBPs) regulate T-cell differentiation and cytokine production in vivo remain unclear. The RBP HuR binds to labile mRNAs, usually leading to increases in mRNA stability and/or translation. Previous work demonstrated that HuR binds to the mRNAs encoding the Th2 transcription factor trans-acting T-cell-specific transcription factor (GATA-3) and Th2 cytokines interleukin (IL)-4 and IL-13, thereby regulating their expression. By using a novel conditional HuR knockout (KO) mouse in which HuR is deleted in activated T cells, we show that Th2-polarized cells from heterozygous HuR conditional (OX40-Cre HuR(fl/+)) KO mice had decreased steady-state levels of Gata3, II4 and II13 mRNAs with little changes at the protein level. Surprisingly, Th2-polarized cells from homozygous HuR conditional (OX40-Cre HuR(fl/fl)) KO mice showed increased II2, II4 and II13 mRNA and protein via different mechanisms. Specifically, II4 was transcriptionally upregulated in HuR KO T cells, whereas II2 and II13 mRNA stabilities increased. Additionally, when using the standard ovalbumin model of allergic airway inflammation, HuR conditional KO mice mounted a robust inflammatory response similar to mice with wild-type HuR levels. These results reveal a complex differential posttranscriptional regulation of cytokines by HuR in which gene dosage plays an important role. These findings may have significant implications in allergies and asthma, as well as autoimmune diseases and infection.