VIRAL SMALL RNPS AND CELL TRANSFORMATION

产品说明：（申请人的描述）正在研究在由两种疱疹病毒转化的淋巴细胞中发现的小核RNA-蛋白质（snRNP）复合物的作用。EB病毒感染并转化人B细胞，是传染性单核细胞增多症的病原体，并且与几种人类癌症相关。松鼠猴疱疹病毒在新世界猴中诱导致命性淋巴瘤和白血病，在新世界猴中转化人和猴T淋巴细胞和白血病，并在培养物中转化人和猴T淋巴细胞。在转化细胞中表达的少数病毒基因产物中有两个EBV编码的EBER和七个H。萨米里编码的HSUR。这些小的核RNA是丰富的、保守的，并且与作为细胞snRNP的组分的宿主自身抗原相关联。然而，EBER和HSUR两者对于转化的病毒生长都是非必需的。提出的实验是基于这样的假设，即EBER和HSUR通过隔离重要的宿主蛋白质来扰乱细胞代谢，从而促进转化。EBER 1结合宿主核糖体蛋白L22的重要部分，其参与某些急性髓性白血病患者的染色体易位。EBER 1与L22相互作用的后果将通过定位60 S核糖体中的L22结合位点并询问L22耗尽的核糖体是否增强核抗原（EBNA）mRNA中上游AUG的通读以增加其在潜伏期期间的翻译来研究。HSUR 1、2和5在其5'末端具有结合HuR的AU 3A基序，HuR是一种宿主蛋白，其过表达稳定了原癌基因、细胞因子和淋巴因子的通常短寿命mRNA。HUR的核质穿梭基序及其与几种蛋白磷酸酶2A（PP 2A）抑制剂的相互作用，其中一种据报道具有肿瘤抑制活性，将通过突变分析进行剖析。将研究AU 3A指导的RNA衰变的亚细胞位置以及HuR和hnRNPD在mRNA稳定性中发挥相反作用的可能性。将研究人乳头瘤病毒E6/E7癌蛋白的表达，以确定PP 2A抑制剂和HuR是否是调节mRNA稳定性的磷酸化级联的组分。在非洲爪蟾系统中，将研究AU 3A指导的mRNA去腺苷化/衰变的机制及其在早期发育过程中的调节。EBER 2和HSUR 3、4、6和7 snRNP的功能的线索将通过鉴定相互作用蛋白来寻找。

DESCRIPTION: (Applicant's Description) The roles of small nuclear RNA- protein (snRNP) complexes found in lymphoid cells transformed by two herpesviruses are being investigated. Epstein-Barr virus infects and transforms human B cells and is the causative agent of infectious mononucleosis, as well as being associated with several human cancers. Herpesvirus saimiri induces fatal lymphomas and leukemias in New World monkeys and transforms human and monkey T lymphocytes and leukemias in New World monkeys and transforms human and monkey T lymphocytes in culture. Among the few viral gene products expressed in transformed cells are the two EBV-encoded EBERs and the seven H. saimiri-encoded HSURs. These small nuclear RNAs are abundant, conserved, and associate with host auto-antigens that are components of cellular snRNPs. Yet, both EBERs and HSURs are non-essential for viral growth of transformation. Proposed experiments are based on the hypothesis that EBERs and HSURs perturb cellular metabolism by sequestering important host proteins, thereby facilitating transformation. EBER1 binds a significant fraction of the host's ribosomal protein L22, whose is involved in chromosomal translocations in some patients with acute myeloid leukemia. Consequences of EBER1 interaction with L22 will be studied by locating the L22 binding site in the 60S ribosome and asking whether L22-depleted ribosomes enhance the read-through of upstream AUGs in nuclear antigen (EBNA) mRNAs to increase their translation during latency. HSURs 1, 2, and 5 have AU3A motifs at their 5' ends that bind HuR, a host protein whose over-expression stabilizes the normally short-lived mRNAs for proto-oncogenes, cytokines and lymphokines. HUR's nucleo- cytoplasmic shuttling motif and its interactions with several protein phosphatase 2A (PP2A) inhibitors, one of which is reported to have tumor suppressor activity will be dissected by mutational analyses. The subcellular location of AU3A-directed RNA decay and the possibility that HuR and hnRNPD play opposing roles in MRNA stability will be investigated. The expression of human papillomavirus E6/E7 oncoproteins will be studied to establish whether the PP2A inhibitors and HuR are components of a phosphorylation cascade regulating mRNA stability. The mechanism of AU3A-directed mRNA deadenylation/decay and its regulation during early development will be studied in the Xenopus system. Clues to the functions of the EBER2 and HSUR 3, 4, 6 and 7 snRNPs will be sought by identifying interaction proteins.