HTLV-I Tax activates the anaphase promoting complex

HTLV-I Tax 激活后期促进复合物

基本信息

批准号：
7409986
负责人：
CHOU-ZEN GIAM
金额：
$ 27.65万
依托单位：
HENRY M. JACKSON FDN FOR THE ADV MIL/MED
依托单位国家：
美国
项目类别：
财政年份：
2005
资助国家：
美国
起止时间：
2005-06-23 至 2010-04-30
项目状态：
已结题

来源：
https://reporter.nih.gov/project-details/7409986
关键词：
Address Adenoviruses Adult Adult Lymphoma Anaphase Aneuploidy Appendix Atypical lymphocyte Binding Biochemical Biochemical Genetics Biologic Characteristic Blood Cell Cycle Cell Cycle Arrest Cell Cycle Stage Cell Nucleus Cells Characteristics Chromosomal Instability Chromosome abnormality Chromosomes Cleaved cell Clinical Code Commit Complex Cyclin A Cyclin B Cyclin E Cyclin-Dependent Kinases Cyclins DNA DNA Sequence Rearrangement Data Defect Development Diploidy Exhibits Fibroblasts Genes Genetic Genetic Transcription Genome Hela Cells Human Human Papillomavirus Individual Infection Lentivirus Vector Life Cycle Stages Link Malignant Neoplasms Manuscripts Mediating Metaphase Mitosis Mitotic Names Nature Oncogene Proteins Phase Phenotype Play Polylobated T-Lymphocyte Polyubiquitination Proliferating Property Research Retroviral Vector Rodent Role Saccharomyces cerevisiae Saccharomycetales Schedule Spinal Cord Diseases Staging Suppressor Mutations T-Cell Leukemia T-Lymphocyte Taxes Telefacsimile Thinking Time Toes Trans-Activators Trisomy 3 Trisomy 7 Tropical Spastic Paraparesis Viral Viral Oncogene Virus WI 38 cell Yeasts adult leukemia anaphase-promoting complex base cell growth cell transformation cyclin B1 cyclin-dependent kinase inhibitor 1B experience human PTTG1 protein inhibitor/antagonist leukemia/lymphoma micronucleus multicatalytic endopeptidase complex nervous system disorder senescence tax Genes ubiquitin-protein ligase yeast genetics

项目摘要

DESCRIPTION (provided by applicant): How HTLV-I infection progresses from clinical latency to adult T-cell leukemia/lymphoma (ATL) is not well understood but involves the unique viral transactivator/oncoprotein, Tax. Unlike cells of other leukemia, ATL cells are often aneuploid with highly lobulated or convoluted nuclei, earning them the name of "flower" cells. Atypical lymphocytes that are binucleated or contain cleaved/cerebriform nuclei are also readily seen in the blood smears of HTLV-I-infected individuals. These pathological findings suggest that mitotic aberrations accompany HTLV-I viral replication and are likely to play an important role in the development of malignancy. We have discovered that naive cells (S. cerevisiae, HeLa, and human diploid fibroblast) that express Tax for the first time become stalled in S/G2/M progression. They then undergo faulty mitosis characterized by severe chromosome aneuploidy, and formation of micronucleated, binucleated and multinucleated cells. We have shown further that Tax causes a significant reduction in Pds1p/securin (the anaphase inhibitor) and Clb2p/cyclin B levels in yeast, rodent, and human cells. This loss of Pds1p/securin and Clb2p/cyclin B1 occurs during S/G2, and strongly correlates with the aforementioned mitotic aberrations. Taking advantage of the genetics of S. cerevisiae, we have found that the unscheduled degradation of Pds1p and Clb2p can be linked to the aberrant activation (by Tax) of an E3 ubiquitin ligase, the Cdc20-associated anaphase promoting complex (APC[Cdc20]), which regulates metaphase to anaphase transition by targeting the timely polyubiquitination and destruction of cyclin A, securin and cyclin B1. Guided by yeast genetics, we have further demonstrated that Tax directly binds and activates human APC[Cdc20] during S phase, ahead of the normal schedule. The cell cycle aberrations induced by Tax does not end with just mitotic abnormalities. We have discovered recently that immediately after experiencing the mitotic crisis described above, Tax+ HeLa cells become permanently arrested in G1, and enter into a senescence-like state with drastically elevated levels of p21[CIP1/WAF1 and p27[KIP1]. Importantly, this senescence phenotype can be explained by the unscheduled activation of APC[Cdc20] and the loss of Skp2 (most likely APC-mediated), the substrate-recognition subunit of SCF[Skp2], a distinct E3 ubiquitin ligase that targets P21[CIP1/WAF1] and p27[KIP1] degradation. Interestingly, the severe mitotic crisis and senescence detected in previously Tax-naive cells are not seen in HTLV-I transformed T-cells, which produce Tax abundantly. This suggests that HTLV-I transformed cells may harbor specific "suppressor" mutations that allow them to escape the senescence state induced by Tax. In this application, we seek to investigate further (1) the mechanism by which Tax activates APC[Cdc20], (2) the biological characteristics of and biochemical basis for the senescence-like state induced by Tax, and (3) the "suppressor" mechanism(s) in HTLV-I transformed cells that allow them to escape the rapid senescence induced by Tax.

描述（由申请人提供）：HTLV-I 感染如何从临床潜伏期进展为成人 T 细胞白血病/淋巴瘤 (ATL) 尚不清楚，但涉及独特的病毒反式激活因子/癌蛋白 Tax。与其他白血病细胞不同，ATL 细胞通常是非整倍体，具有高度分叶或卷曲的细胞核，因此被称为“花”细胞。在 HTLV-I 感染者的血涂片中也很容易看到双核或含有分裂/脑状细胞核的非典型淋巴细胞。这些病理学发现表明，有丝分裂畸变伴随着HTLV-I病毒复制，并且可能在恶性肿瘤的发展中发挥重要作用。我们发现首次表达 Tax 的初始细胞（酿酒酵母、HeLa 和人二倍体成纤维细胞）在 S/G2/M 进程中陷入停滞。然后，它们经历以严重染色体非整倍体为特征的错误有丝分裂，并形成微核、双核和多核细胞。我们进一步表明，Tax 会导致酵母、啮齿动物和人类细胞中 Pds1p/securin（后期抑制剂）和 Clb2p/cyclin B 水平显着降低。 Pds1p/securin 和 Clb2p/cyclin B1 的丢失发生在 S/G2 期间，并且与上述有丝分裂畸变密切相关。利用酿酒酵母的遗传学优势，我们发现 Pds1p 和 Clb2p 的意外降解可能与 E3 泛素连接酶（Cdc20 相关的后期促进复合物 (APC[Cdc20]) 的异常激活（通过 Tax）有关。），它通过针对细胞周期蛋白 A、securin 和 cyclin A 的及时多泛素化和破坏来调节中期到后期的转变。细胞周期蛋白B1。在酵母遗传学的指导下，我们进一步证明了Tax在S期直接结合并激活人类APC[Cdc20]，提前于正常时间表。 Tax 引起的细胞周期畸变并不仅仅以有丝分裂异常结束。我们最近发现，在经历上述有丝分裂危机后，Tax+ HeLa 细胞立即永久停滞在 G1 期，并进入类衰老状态，p21[CIP1/WAF1 和 p27[KIP1] 水平急剧升高。重要的是，这种衰老表型可以通过 APC[Cdc20] 的意外激活和 Skp2 的丢失（很可能是 APC 介导的）来解释，Skp2 是 SCF[Skp2] 的底物识别亚基，SCF[Skp2] 是一种针对 P21 的独特 E3 泛素连接酶。 CIP1/WAF1] 和 p27[KIP1] 降解。有趣的是，在先前未接触过Tax的细胞中检测到的严重有丝分裂危机和衰老在大量产生Tax的HTLV-I转化T细胞中并未观察到。这表明HTLV-I转化细胞可能含有特定的“抑制”突变，使它们能够逃避Tax诱导的衰老状态。在本申请中，我们试图进一步研究（1）Tax激活APC[Cdc20]的机制，（2）Tax诱导的衰老样状态的生物学特性和生化基础，以及（3）“抑制剂” HTLV-I 转化细胞中的机制使它们能够逃避由 Tax 引起的快速衰老。