Cell Cycle G2/M Pathway Modulated by Viral Protein R

病毒蛋白 R 调节细胞周期 G2/M 通路

• 批准号: 6943012
• 负责人: RICHARD YUQI ZHAO
• 金额: $ 21.57万
• 依托单位: UNIVERSITY OF MARYLAND BALTIMORE
• 依托单位国家: 美国
• 财政年份: 2002
• 资助国家: 美国
• 起止时间: 2002-09-01 至 2008-08-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6943012
• 关键词: DNA damage; DNA replication; casein kinase; caseins; cell cycle; cell cycle proteins; enzyme activity; gene mutation; human immunodeficiency virus 1; immunoprecipitation; phosphoprotein phosphatase; phosphorylation; polymerase chain reaction; protein kinase; protein protein interaction; tyrosine; virus protein; yeasts

DESCRIPTION (provided by applicant): Progression of cells from G2 phase of the cell cycle to mitosis is a tightly regulated process that requires activation of the Cdc2 kinase, which determines onset of mitosis in all eukaryotic cells. In fission yeast (Schizosaccharomyces pombe), the activity of Cdc2 is regulated by the phosphorylation status of tyrosine 15 (Tyr 15) on Cdc2, which is phosphorylated by Wee1 and Mik1 tyrosine kinases during late G2 and is rapidly dephosphorylated by the Cdc25 phosphatase to trigger entry into mitosis. Cdc25, Wee1 and Mik1 are the targets of two well-characterized regulatory pathways, the DNA damage and DNA replication checkpoints, which both cause cell cycle arrest by inhibitory phosphorylation of Tyr15 on Cdc2 primarily through inhibition of Cdc25.The viral protein R (Vpr) of HIV-1 induces G2 arrest in cells from distantly related eukaryotes, including fission yeast and human. Similar to the two checkpoint pathways, Vpr also induces G2 arrest in fission yeast through inhibitory phosphorylation of Tyr15. However, Vpr does not use any of the early or late steps in the checkpoint pathways, and instead it acts primarily through activation of Wee1, protein phosphatase 2A (PP2A) and to a lesser extent inhibition of Cdc25, suggesting that Vpr induces G2 arrest through a novel PP2A-mediated regulatory pathway. The goal of this proposal is to use fission yeast as a model system to test this hypothesis and to elucidate this new G2/M regulatory pathway. The three specific aims are to 1) define the regulatory effects of PP2A on Wee1 and Cdc25 when Vpr induces G2 arrest; 2) characterize a potential protein complex of Vpr with PP2A and casein kinase II alpha (CKIIa) and define the role of this complex in Vpr-induced G2 arrest, and 3) characterize four multicopy Vpr-specific suppressors (Wos2 and Vsp24C8)/enhancers (Rad25 and Sum1) and their role in Vprinduced G2 arrest. These proposed studies will provide a comprehensive framework for this new cell cycle control pathway and provide insights into fundamental aspects of this new G2/M surveillance system of eukaryotic cells.

描述（由申请人提供）：细胞从G2阶段的进展 细胞周期至有丝分裂是一个严格调节的过程，需要激活 Cdc2激酶，该激酶决定了所有真核细胞中有丝分裂的发作。 在裂变酵母（schizosacchomyces pombe）中，调节Cdc2的活性 通过酪氨酸15（Tyr 15）在Cdc2上的磷酸化状态， 在G2晚期，由WEE1和MIK1酪氨酸激酶磷酸化，迅速 由CDC25磷酸酶脱磷酸化，以触发有丝分裂。 cdc25， WEE1和MIK1是两个特征良好的调节途径的目标，即 DNA损伤和DNA复制检查点，这两者都会导致细胞周期 通过Tyr15对Cdc2的抑制性磷酸化抑制主要通过 CDC25的抑制作用。HIV-1的病毒蛋白R（VPR）诱导G2停滞 来自遥远相关的真核生物的细胞，包括裂变酵母和人。 与两个检查点途径相似，VPR还引起了G2逮捕 通过Tyr15的抑制性磷酸化酵母。但是，VPR不使用 检查点途径中的任何早期或晚期的步骤，相反 主要通过激活WEE1，蛋白质磷酸酶2a（PP2A）和A CDC25的抑制程度较小，这表明VPR诱导了G2停滞 通过一种新型的PP2A介导的调节途径。该提议的目的是 使用裂变酵母作为模型系统来检验此假设并阐明 这项新的G2/M监管途径。三个具体目标是1）定义 当VPR诱导G2停滞时，PP2A对WEE1和CDC25的调节作用； 2） 表征VPR的潜在蛋白质复合物与PP2A和酪蛋白激酶II alpha（CKIIA），并定义了该建筑物在VPR引起的G2逮捕中的作用，并且 3）表征四个多拷贝VPR特异性抑制器（WOS2和 VSP24C8）/增强子（RAD25和SUM1）及其在VPRAPPRATS诱导的G2停滞中的作用。 这些拟议的研究将为这个新细胞提供一个全面的框架 循环控制途径，并提供有关此新的基本方面的见解 真核细胞的G2/M监测系统。