E1A-CtBP interactions in oncogenic transformations

描述（由申请方提供）：腺病毒E1 A C-末端CR 4区通过高度保守的序列基序PLDLS与细胞CtBP家族蛋白CtBP 1和CtBP 2相互作用。CtBP 1和CtBP 2作为转录辅抑制因子，在脊椎动物的发育、肿瘤发生和凋亡调控中发挥重要作用。它们在某些发育过程中是功能冗余的，而在某些其他过程中则发挥独特的作用。CtBP 2是高度核化的，CtBP 1是核和胞质的。CtBPs通过募集几种组蛋白修饰酶组分如组蛋白脱乙酰酶、甲基转移酶和组蛋白脱甲基酶来介导序列特异性转录抑制。此外，CtBP蛋白复合物还含有介导蛋白质SUMO修饰的E2和E3酶。腺病毒E1 A突变体与CtBPs相互作用不足，表现出与Ras癌基因合作的超转化表型。表达E1 A CR 4突变体和Ras癌基因的转化细胞具有高度致瘤性和转移性。我们推测E1 A与CtBP的相互作用可能调节与E1 A的N-末端区域相关的细胞蛋白的活性。此外，E1 A与CtBP的相互作用也可能导致细胞CtBP靶基因模式的显著变化。目的1：研究E1 A C端CR 4区和CtBPs对E1 A N端Ras癌基因协同活性的影响。目的2阐明CtBP 2独特的转录活性，并确定E1 A对CtBP 2介导的细胞靶基因表达调控的影响。目的3：研究E1 A对CtBP 1胞浆和核功能的影响。目的4阐明CtBP相关SUMO化机制在转录抑制中的作用。 与公共卫生的相关性：大约三分之一的人类癌症在Ras癌基因中含有致癌突变。类似地，Myc癌基因也在人类恶性肿瘤中起主导作用。E1 A和Myc共享的某些功能与Ras致癌转化合作，而E1 A与CtBP的相互作用拮抗这种活性。我们提出的研究将利用从病毒癌蛋白E1 A的研究中获得的知识，以揭示潜在的新的肿瘤发生机制，并提出抑制人类这一过程的策略。

DESCRIPTION (provided by applicant): Adenovirus E1A C-terminal CR4 region interacts with the cellular CtBP family proteins, CtBP1 and CtBP2 through a highly conserved sequence motif, PLDLS. CtBP1 and CtBP2 function as transcriptional corepressors and play critical roles during development, oncogenesis and apoptosis regulation in vertebrates. They are functionally redundant for several developmental processes while exerting unique activities with regard to certain other processes. CtBP2 is highly nuclear and CtBP1 is both nuclear and cytosolic. The CtBPs mediate sequence specific transcriptional repression by recruitment of several histone modifying enzymatic constituents such as histone deacetylases, methyl transferases and a histone demethylase. Additionally, the CtBP protein complex also contains E2 and E3 enzymes that mediate SUMO modification of proteins. Adenovirus E1A mutants deficient in interaction with CtBPs exhibit a hyper-transforming phenotype in cooperation with the Ras oncogene. The transformed cells expressing E1A CR4 mutant and the Ras oncogene are highly tumorigenic and metastatic. We hypothesize that interaction of E1A with CtBP might modulate the activities of cellular proteins associated with the N-terminal region of E1A. Additionally, interaction of E1A with CtBP might also cause significant changes in the pattern of cellular CtBP target genes. In Aim 1, we will determine the effects of E1A C-terminal CR4 region and CtBPs on the Ras oncogene cooperating activity of the E1A N-terminal region. Aim 2 will elucidate the unique transcriptional activities of CtBP2 and to determine the effect of E1A on CtBP2- mediated regulation of expression of cellular target genes. Aim 3 will determine the effect of E1A in the cytosolic and nuclear functions of CtBP1. Aim 4 will elucidate the role of CtBP-associated SUMOylation machinery in transcriptional repression. Relevance to Public Health: About one third of all human cancers contain oncogenic mutations in the Ras oncogene. Similarly, the Myc oncogene also plays a dominant role in human malignancies. Certain functions shared by E1A and Myc cooperate with Ras oncogenic transformation while interaction of E1A with CtBP antagonizes such activity. Our proposed studies will harness the knowledge gained from the study of the viral oncoprotein E1A to unravel potential new mechanisms governing oncogenesis and suggest strategies to inhibit the process in humans.