The Novel Oncogene Jcf1 in Development and Oncogenesis

描述(由申请人提供)：对MoMuLV诱导的大鼠T细胞淋巴瘤的常见整合位点进行全基因组筛查，导致鉴定出一种新的癌基因Jcf1，它是本提案的主题。Jcf1在致癌基因中是独一无二的，因为它促进了动物原代肿瘤细胞的生长，但在培养中是必不可少的。该基因编码的蛋白质全长1336个氨基酸，包含一个Jumonji(JmjC)结构域、一个CXXC/PHD2锌指结构域、一个F盒和一个富含亮氨酸的重复序列(LRR)，定位于细胞核内。JmjC结构域被认为参与染色质修饰和重塑，强调其重要性的是，在146个克隆的前病毒中发现了另外三个整合有靶向基因的基因，这些基因也编码含有JmjC结构域的蛋白。以F-box/LRR结构域为诱饵的双杂交筛选鉴定出几种相互作用的蛋白质，它们参与转录、DNA修复和细胞凋亡的调节。此外，稳定或瞬时表达该基因的细胞株Jcf1诱导了内源基因的表达，从而证实了Jcf1是一个调节基因的表达。NIH3T3细胞的血清饥饿和IL-2依赖的T细胞淋巴瘤细胞系的IL-2饥饿导致Jcf1表达急剧下降。再次暴露于血清或IL-2可迅速诱导Jcf1，提示Jcf1可能通过细胞周期的G1期参与细胞的再入和进展。此外，在培养的骨髓单核细胞系分化过程中，Jcf1的表达下降到检测不到的水平，这表明它可能在髓系细胞的分化中起作用。Jcf1是一种高度保守的蛋白质。利用先前存在的Jcf1Drosphila突变体，通过在基因的前两个内含子中插入P元素而产生的突变体，我们证明了DJcf1在发育过程中是必需的。这里提出的实验将利用分子生物学、组织培养和遗传策略来解决Jcf1在发育和肿瘤发生中的作用。

DESCRIPTION (provided by applicant): A genome-wide screen for loci of common integration in MoMuLV-induced rat T cell lymphomas, led to the identification of a novel oncogene, Jcf1, which is the subject of this proposal. Jcf1is unique among oncogenes, in that it promotes the growth of primary tumor cells in animals but is dispensable in culture. The protein encoded by this gene is 1336 amino acids long, contains a jumonji (JmjC) domain, a CXXC/PHD2 zinc finger domain, an F box and a leucine rich repeat (LRR) and is localized in the nucleus. Underscoring the importance of the JmjC domain, which is thought to be involved in chromatin modification and remodeling, was the finding that three additional provirus integrations among 146 cloned had targeted genes that also encode JmjC domain-containing proteins. A two-hybrid screen using the F-box/LRR domain as the bait identified several interacting proteins that are involved in transcription, DNA repair and the regulation of apoptosis. Moreover, stable or transient transfections of Jcf1in cell lines that express this gene at very low levels induced the expression of the endogenous gene, thus confirming that Jcf1is a regulator gene expression. Serum starvation of NIH 3T3 cells and IL-2 starvation of an IL-2 dependent T cell lymphoma line led to a precipitous drop in Jcf1expression. Reexposure to serum or IL-2 respectively induced Jcf1rapidly, suggesting that Jcf1may have a role in the reentry and progression of cells through the G1 phase of the cell cycle. Moreover, the expression of Jcf1declined to undetectable levels in the course of differentiation of a myelomonocytic cell line in culture suggesting that it may have a role in myeloid cell differentiation. Jcf1is a highly conserved protein. Using preexisting Jcf1Drosphila mutants, generated by P element insertions in the first two introns of the gene, we demonstrated that DJcf1 is required during development. Experiments proposed here will utilize molecular biology, tissue culture and genetic strategies to address the role of Jcf1in development and oncogenesis.