EBNA1 Functions Required in Burkitt's Lymphomas and Other Immortalized B-Cells

伯基特淋巴瘤和其他永生化 B 细胞所需的 EBNA1 功能

• 批准号: 7911413
• 负责人: Amber Teresa Keizerweerd
• 金额: $ 2.88万
• 依托单位: LSU HEALTH SCIENCES CENTER
• 依托单位国家: 美国
• 财政年份: 2010
• 资助国家: 美国
• 起止时间: 2010-07-01 至 2014-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7911413
• 关键词: AIDS Related Immunoblastic Lymphoma; AT-Hook Motifs; Affect; Apoptosis; B Cell Proliferation; B-Cell Lymphomas; B-Lymphocytes; Binding; Burkitt Lymphoma; Carcinoma; Cell Proliferation; Cells; Communicable Diseases; Cysteine; DNA; Diagnosis; Disease; Dominant-Negative Mutation; Epstein-Barr Virus Infections; Gene Expression; Genes; Genetic Transcription; Genome Stability; Goals; Growth; Health; Herpesviridae; Human; Human Herpesvirus 4; In Vitro; Individual; LMP1; Lymphoma; Lymphoproliferative Disorders; Malignant - descriptor; Malignant Neoplasms; Nasopharynx Carcinoma; Nuclear; Nuclear Antigens; Oncogenic; Oxidation-Reduction; Oxidative Stress; Pattern; Publishing; Reactive Oxygen Species; Reporting; Research; Social Welfare; Stomach Carcinoma; Therapeutic; Transactivation; Transplantation; Viral Genes; Viral Proteins; Virus; Woman; Zinc; cancer statistics; cytochrome b245; infected B cell; lymphoblastoid cell line; men; new therapeutic target; public health relevance

DESCRIPTION (provided by applicant): Epstein-Barr Virus (EBV) is an oncogenic human herpesvirus predominantly infecting B-lymphocytes that is etiologically associated with Burkitt's lymphoma, AIDS-related immunoblastic lymphomas, post- transplant lymphoproliferative disease, nasopharyngeal carcinoma, and gastric carcinoma. Very few viral genes are expressed in these malignancies and diseases, and infectious virus is almost never released. Therefore, this type of EBV infection is called latency. There are three patterns of viral gene expression observed during latency, termed Type I, Type II and Type III. A nuclear EBV protein called the Epstein-Barr nuclear antigen 1 (EBNA1) is expressed during all three types of latency, but its function differs between latency types. In Type II and Type III latency, EBNA1 activates transcription of other viral genes required for cell proliferation, such as LMP1 and EBNA2. Type II latency is usually observed in EBV-associated carcinomas, whereas Type III latency is observed in AIDS-related immunoblastic lymphomas, post-transplant lymphoproliferative disease, and when EBV immortalizes naive B-cells in vitro. EBNA1 does not transactivate viral genes during Type I latency, which is observed in malignancies such as Burkitt's lymphomas. However, in such cells, EBNA1 has been reported to transactivate the expression of cellular genes. In addition, expression of a dominant-negative EBNA1 that cannot activate transcription severely reduces the aggressive proliferation of EBV-positive Burkitt's lymphoma cells, and induces apoptosis in the majority of cells. Surprisingly, in contrast to these results, over-expression of EBNA1 inhibits the growth of EBV-negative Burkitt's lymphoma cells. Therefore, the ability of EBNA1 to transactivate has contrasting effects on the growth and survival of EBV-positive and EBV-negative Burkitt's lymphomas. A study published recently demonstrates that EBNA1 induces reactive oxygen species (ROS) when expressed in Burkitt's lymphomas, and thereby negatively affects genomic stability. EBNA1 generates ROS by increasing the expression of cytochrome b-245 heavy chain (NOX2). Recent studies on the transactivation mechanism of EBNA1 have shown that EBNA1 needs three domains to transactivate: a) two domains that bind AT-rich DNA, and are termed AT-hooks; and b) a domain called unique region 1 (UR1) that contains an essential conserved cys-x-x-cys motif that permits EBNA1 to dimerize by coordinating zinc. The two cysteines in UR1 are regulated by oxidative stress (redox), such that under oxidative conditions, EBNA1 does not transactivate viral genes. These conditions also interfere with the proliferation of B-cells transformed by EBV in vitro. I propose investigating the functions and domains of EBNA1 required for proliferation of EBV-immortalized lymphoblastoid cell lines, and EBNA1 functions necessary for the aggressive proliferation of malignant Burkitt's lymphoma cells. My studies will identify new therapeutic targets against diseases and malignancies caused by latent EBV infections. PUBLIC HEALTH RELEVANCE: The NCI SEER Cancer Statistics Review indicates that an estimated 75000 men and women will be diagnosed with, and 20,000 individuals will die from lymphoma this year in the US. Infection by Epstein-Barr virus results in 30-50% of B-cell lymphomas. This goal of my research is to yield therapeutics that decrease those numbers, and therefore augment human health and welfare.

描述（由申请方提供）：EB病毒（EBV）是一种主要感染B淋巴细胞的致癌人类疱疹病毒，与伯基特淋巴瘤、艾滋病相关免疫母细胞性淋巴瘤、移植后淋巴组织增生性疾病、鼻咽癌和胃癌在病因学上相关。在这些恶性肿瘤和疾病中表达的病毒基因很少，感染性病毒几乎从不释放。因此，这种类型的EBV感染被称为潜伏期。在潜伏期期间观察到三种病毒基因表达模式，称为I型、II型和III型。一种称为EB病毒核抗原1（EBNA 1）的核EBV蛋白在所有三种潜伏期中都有表达，但其功能在潜伏期类型之间存在差异。在II型和III型潜伏期，EBNA 1激活细胞增殖所需的其他病毒基因的转录，如LMP 1和EBNA 2。II型潜伏期通常在EBV相关的癌中观察到，而III型潜伏期在AIDS相关的免疫母细胞淋巴瘤、移植后淋巴增生性疾病以及当EBV在体外使幼稚B细胞永生化时观察到。EBNA 1在I型潜伏期期间不反式激活病毒基因，这在恶性肿瘤如伯基特淋巴瘤中观察到。然而，在这样的细胞中，EBNA 1已被报道反式激活细胞基因的表达。此外，不能激活转录的显性阴性EBNA 1的表达严重降低了EBV阳性伯基特淋巴瘤细胞的侵袭性增殖，并诱导大多数细胞的凋亡。令人惊讶的是，与这些结果相反，EBNA 1的过表达抑制EBV阴性伯基特淋巴瘤细胞的生长。因此，EBNA 1的反式激活能力对EBV阳性和EBV阴性伯基特淋巴瘤的生长和存活具有对比效应。最近发表的一项研究表明，EBNA 1在伯基特淋巴瘤中表达时诱导活性氧（ROS），从而对基因组稳定性产生负面影响。EBNA 1通过增加细胞色素B-245重链（NOX 2）的表达产生ROS。最近对EBNA 1的反式激活机制的研究表明，EBNA 1需要三个结构域来进行反式激活：a）两个结合富含AT的DNA的结构域，称为AT-钩;和B）称为独特区1（UR 1）的结构域，其包含必需的保守cys-x-x-cys基序，其允许EBNA 1通过配位锌而二聚化。UR 1中的两个半胱氨酸受氧化应激（氧化还原）调节，因此在氧化条件下，EBNA 1不会反式激活病毒基因。这些条件也干扰体外由EBV转化的B细胞的增殖。我建议调查EBNA 1的功能和结构域所需的EBV永生化淋巴母细胞系的增殖，和恶性伯基特淋巴瘤细胞的侵袭性增殖所需的EBNA 1功能。我的研究将确定新的治疗靶点，以对抗潜伏性EBV感染引起的疾病和恶性肿瘤。 公共卫生关系：NCI SEER癌症统计回顾表明，估计今年美国将有75000名男性和女性被诊断患有淋巴瘤，20，000人将死于淋巴瘤。EB病毒感染导致30-50%的B细胞淋巴瘤。我的研究目标是产生减少这些数字的治疗方法，从而增加人类的健康和福利。