The Novel Oncogene Jcf1 in Development and Oncogenesis

描述（由申请人提供）：对momulv诱导的大鼠T细胞淋巴瘤的共同整合位点进行全基因组筛选，鉴定出一种新的致癌基因Jcf1，这是本提案的主题。jcf1在癌基因中是独特的，它在动物中促进原发肿瘤细胞的生长，但在培养中是可有可无的。该基因编码的蛋白全长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 box和一个leucine rich repeat (LRR)，定位于细胞核中。强调JmjC结构域（被认为参与染色质修饰和重塑）的重要性的是，在146个克隆的前病毒整合中发现了另外三个靶向基因，这些基因也编码含有JmjC结构域的蛋白质。以F-box/LRR结构域为诱饵的双杂交筛选发现了几个参与转录、DNA修复和细胞凋亡调控的相互作用蛋白。此外，在极低水平表达jcf1的细胞系中，稳定或短暂转染jcf1可诱导内源基因的表达，从而证实jcf1是一种调节基因表达。NIH 3T3细胞的血清饥饿和IL-2依赖性T细胞淋巴瘤系的IL-2饥饿导致jcf1表达急剧下降。再次暴露于血清或IL-2分别快速诱导jcf1，提示jcf1可能在细胞周期G1期的细胞再进入和进展中起作用。此外，jcf1的表达在培养的骨髓单核细胞分化过程中下降到无法检测的水平，这表明它可能在骨髓细胞分化中起作用。jcf1是一种高度保守的蛋白。利用先前存在的jcf1果蝇突变体，通过在基因的前两个内含子插入P元素产生，我们证明了DJcf1在发育过程中是必需的。本文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.