Reverse Transcriptase Activity in Megakaryocytes and Platelets

巨核细胞和血小板中的逆转录酶活性

• 批准号: 7359528
• 负责人: Andrew S Weyrich
• 金额: $ 22.58万
• 依托单位: UNIVERSITY OF UTAH
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-07-01 至 2011-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7359528
• 关键词: 2' -Deoxythymidine; Abbreviations; Affect; B-Cell Lymphomas; Blood Platelets; Cell Nucleus; Cells; Clinical; Code; Complementary DNA; DNA; Elements; Eukaryotic Cell; Family; Functional RNA; Gene Expression; Genes; Genetic Transcription; Genome; Genomics; HERVs; HIV; Hemophilia A; Human; Human Activities; Individual; Information Distribution; Interleukin-1; Introns; L1 Elements; Link; Long Terminal Repeats; Megakaryocytes; Megakaryocytopoieses; Messenger RNA; Mitochondrial DNA; Molecular Chaperones; Muscle; Nuclear; Nucleic Acids; Open Reading Frames; Pathway interactions; Patients; Pattern; Phosphotransferases; Platelet Transfusion; Process; Proteins; RNA; RNA Splicing; RNA-Binding Proteins; RNA-Directed DNA Polymerase; Retrotransposon; Reverse Transcriptase Inhibitors; Reverse Transcription; Role; Signal Transduction; Site; Small Nuclear RNA; Small Nuclear Ribonucleoproteins; Spliceosomes; Stereotyping; Stimulus; Structure; Testing; Thalassemia; Thromboplastin; Thrombopoiesis; Time; Untranslated Regions; Uridine; Work; Zidovudine; cell growth; endonuclease; human FRAP1 protein; human stem cells; insight; mRNA Precursor; mTOR protein; non-nucleoside reverse transcriptase inhibitors; novel; response

DESCRIPTION (provided by applicant): The nucleus controls gene expression patterns that characterize the function of individual cells. Responses that occur in the nucleus, such as transcription and splicing of pre-mRNA, are elaborate processes that utilize many factors. Because platelets circulate without a nucleus, they have been stereotyped as a cell that lacks complexity and is devoid of nuclear functions. However, our group has recently shown that platelets carry a functional spliceosome and in response to activating signals, platelets splice pre- mRNA into mature, translatable messages. This result was unexpected because pre- mRNA splicing was previously thought to reside only in the nucleus. Possession of a functional spliceosome demonstrates remarkable specialization and intricate information transfer from parental megakaryocytes to terminally differentiated platelets. It also raises the possibility that megakaryocytes endow platelets with other novel gene expression pathways during thrombopoiesis. Recent evidence indicates that the long interspersed nuclear element (LINE-1; also referred to as L1 elements) family of retrotransposons harbor reverse transcriptase activity that regulates cellular growth, differentiation and gene expression. This suggests that L1 elements may regulate megakaryopoiesis and proplatelet formation. If transferred to proplatelets, L1 elements may also control functional responses in mature, circulating platelets. Whether L1 elements control megakaryocyte and platelet function, however, has not been tested. Therefore, in this R21 application we will explore the possibility that megakaryocytes and platelets possess functional L1 elements. In specific aim 1 we will characterize the L1 machinery in megakaryocytes. We will determine if L1 encoded proteins are present in human stem cell-derived megakaryocytes and if they regulate megakaryocyte differentiation and proplatelet formation. In aim 2 we will characterize the L1 machinery in mature, human platelets. We will determine if L1 elements are present in platelets and if they possess reverse transcriptase activity. We also determine if L1 elements control previously-unrecognized functions of platelets that include insertion of L1 sequences into mitochondrial DNA and reverse transcription of mRNA into cDNA. Studies in aim 2 will examine responses in freshly-isolated platelets and in stored platelets that would otherwise be used for platelet transfusions. Together these studies will provide novel insight into the cellular activities of human megakaryocytes and platelets. Studies in aim 2 will also provide important clinical information, especially in regards to HIV-infected patients who are medicated with reverse transcriptase inhibitors and patients who receive platelet transfusions.

描述（由申请人提供）：细胞核控制表征单个细胞功能的基因表达模式。发生在细胞核中的反应，如前体mRNA的转录和剪接，是利用许多因素的复杂过程。由于血小板在循环中没有细胞核，因此它们被定型为缺乏复杂性和缺乏核功能的细胞。然而，我们的研究小组最近发现，血小板携带一个功能性剪接体，并对激活信号作出反应，血小板将前mRNA剪接成成熟的、可翻译的信息。这个结果是出乎意料的，因为以前认为前mRNA剪接只存在于细胞核中.拥有一个功能性剪接体表现出显着的专业化和复杂的信息从父母的巨核细胞到终末分化的血小板。这也提出了巨核细胞在血小板生成过程中赋予血小板其他新的基因表达途径的可能性。最近的证据表明，逆转录转座子的长散布核元件（LINE-1;也称为L1元件）家族具有调节细胞生长、分化和基因表达的逆转录酶活性。这表明L1元件可能调节巨核细胞和前血小板的形成。如果转移到前血小板，L1元件也可以控制成熟的循环血小板的功能反应。然而，L1元件是否控制巨核细胞和血小板功能还没有被测试。因此，在R21的应用中，我们将探索巨核细胞和血小板具有功能性L1元件的可能性。在具体目标1中，我们将描述巨核细胞中的L1机制。我们将确定L1编码的蛋白质是否存在于人类干细胞衍生的巨核细胞中，以及它们是否调节巨核细胞分化和前血小板形成。在目标2中，我们将描述成熟的人血小板中的L1机制。我们将确定血小板中是否存在L1元件，以及它们是否具有逆转录酶活性。我们还确定，如果L1元件控制血小板，包括插入L1序列到线粒体DNA和逆转录成cDNA的mRNA的功能以前未被认识到。目标2中的研究将检查新鲜分离的血小板和储存的血小板的反应，否则将用于血小板输注。这些研究将为人类巨核细胞和血小板的细胞活性提供新的见解。目标2的研究还将提供重要的临床信息，特别是关于接受逆转录酶抑制剂治疗的艾滋病毒感染患者和接受血小板输注的患者。