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.

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 。在这些恶性肿瘤和疾病中，很少有病毒基因表达，并且几乎从未释放传染性病毒。因此，这种类型的EBV感染称为潜伏期。在潜伏期中观察到的病毒基因表达的三种模式，称为I型，II型和III型。一种称为爱泼斯坦 - 巴尔核抗原1（EBNA1）的核EBV蛋白在所有三种类型的潜伏期中表达，但其功能在潜伏期类型之间有所不同。在II型和III型潜伏期中，EBNA1激活了细胞增殖所需的其他病毒基因的转录，例如LMP1和EBNA2。 II型潜伏期通常在与EBV相关的癌中观察到，而III型潜伏期在与AIDS相关的免疫细胞淋巴瘤，移植后淋巴细胞增生性疾病中观察到，并且当EBV在体外使幼稚的B-Cell无生内。在I型潜伏期期间，EBNA1不会反式激活病毒基因，这在伯基特淋巴瘤等恶性肿瘤中观察到。但是，在此类细胞中，据报道EBNA1反式激活细胞基因的表达。另外，无法激活转录的显性阴性EBNA1的表达严重降低了EBV阳性伯基特淋巴瘤细胞的侵略性增殖，并诱导大多数细胞中的凋亡。令人惊讶的是，与这些结果相反，EBNA1的过表达抑制了EBV阴性伯基特淋巴瘤细胞的生长。因此，EBNA1反式激活的能力对EBV阳性和EBV阴性伯基特的淋巴瘤的生长和存活具有对比影响。最近发表的一项研究表明，EBNA1在Burkitt的淋巴瘤中表达时会诱导活性氧（ROS），从而对基因组稳定性产生负面影响。 EBNA1通过增加细胞色素B-245重链（NOX2）的表达来产生ROS。关于EBNA1的反式激活机理的最新研究表明，EBNA1需要三个结构域进行反式激活：a）两个结合富含富含DNA的且称为挂钩的域； b）一个称为唯一区域1（UR1）的域，其中包含必需的保守的Cys-X-X-Cys基序，该基序允许EBNA1通过协调锌来二聚。 UR1中的两个半胱氨酸受氧化应激（氧化还原）的调节，因此在氧化条件下，EBNA1不会反式激活病毒基因。这些条件还干扰了由EBV在体外转化的B细胞的增殖。我提出了研究EBV免疫性淋巴生物细胞系的增殖所需的EBNA1的功能和结构域，以及EBNA1的功能，对于恶性伯基特淋巴瘤细胞的攻击性增殖所必需的功能。我的研究将确定对潜在EBV感染引起的疾病和恶性肿瘤的新治疗靶标。 公共卫生相关性：NCI SEER癌症统计评论表明，估计有75000名男性和女性将被诊断出患有，今年在美国将死于淋巴瘤。爱泼斯坦 - 巴尔病毒感染导致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剂，从而增加人类健康和福利。