Endogenous LINE-1 (Long Interspersed Nuclear Element-1) Reverse Transcriptase Activity in Platelets Controls Translational Events Through RNA-DNA Hybrids.
Endogenous LINE-1 (Long Interspersed Nuclear Element-1) Reverse Transcriptase Activity in Platelets Controls Translational Events Through RNA-DNA Hybrids.
复制标题
DOI：
10.1161/atvbaha.117.310552
复制
发表时间：
2018-04
期刊：
影响因子：
--
通讯作者：
Rondina MT
中科院分区：
文献类型：
--
作者：
Schwertz H;Rowley JW;Schumann GG;Thorack U;Campbell RA;Manne BK;Zimmerman GA;Weyrich AS;Rondina MT
有核细胞中内源性逆转录酶 (eRT) 活性的一个来源是长散布元件-1 (LINE-1/L1)，它是一种参与基因表达调节的非 LTR 逆转录转座子。然而，人类血小板（一种无核细胞）中 eRT 活性和 LINE-1 的存在和功能此前尚未确定。我们证明人和鼠血小板具有强大的 eRT 活性，并确定其来源为 LINE-1 核糖核蛋白颗粒 (RNP)。在健康个体或经 RT 抑制剂治疗的 HIV 感染者中分离的血小板中，体外抑制 eRT 可增强整体蛋白质合成和血小板活化。如果艾滋病毒患者接受逆转录酶抑制剂治疗，我们发现这些患者的血小板基础活化增加。接下来我们发现血小板中的 eRT 活性控制着 RNA-DNA 杂交体的产生，RNA-DNA 杂交体充当翻译抑制子。血小板 eRT 的抑制解除了这种 RNA-DNA 杂交诱导的翻译阻断，并且足以增加通过 RNA-DNA 杂交免疫沉淀鉴定的靶 RNA 的蛋白质表达。因此，我们提供了血小板具有 L1 编码的 eRT 活性的第一个证据。我们还证明血小板 eRT 活性可调节血小板高反应性和血栓形成，并控制 RNA-DNA 杂交体的形成，并确定 RNA-DNA 杂交体在人类血小板中作为一种新型翻译控制机制发挥作用。
One source of endogenous reverse transcriptase (eRT) activity in nucleated cells is the Long Interspersed Element-1 (LINE-1/L1), a non-LTR retrotransposon that is implicated in the regulation of gene expression. Nevertheless, the presence and function of eRT activity and LINE-1 in human platelets, an anucleate cell, has not previously been determined. We demonstrate that human and murine platelets possess robust eRT activity and identify the source as being LINE-1 ribonucleoprotein-particles (RNPs). Inhibition of eRT in vitro in isolated platelets from healthy individuals or in persons with HIV treated with RT inhibitors enhanced global protein synthesis and platelet activation. If HIV patients were treated with reverse transcriptase inhibitor, we found that platelets from these patients had increased basal activation. We next discovered that eRT activity in platelets controlled the generation of RNA-DNA hybrids, which serve as translational repressors. Inhibition of platelet eRT lifted this RNA-DNA hybrid-induced translational block and was sufficient to increase protein expression of target RNAs identified by RNA-DNA hybrid immunoprecipitation. Thus, we provide the first evidence that platelets possess L1-encoded eRT activity. We also demonstrate that platelet eRT activity regulates platelet hyperreactivity and thrombosis and controls RNA-DNA hybrid formation, and identify that RNA-DNA hybrids function as a novel translational control mechanism in human platelets.