C-MYC EXPRESSION AND APOPTOSIS IN A B CELL LINE

描述(改编自申请人的摘要)：WEHI231和CH33 未成熟的B细胞系已被广泛用作研究 B细胞耐受通过细胞凋亡的克隆性删除。调查员 最近表明，用抗血清处理这些品系 表面免疫球蛋白或转化生长因子-β-1导致核因子-kappaB/Rel活性降低 转录因子，导致c-myc表达下降，从而诱导 细胞凋亡。CD40结扎从细胞凋亡中解救出来导致维持 核因子-kappaB/Rel和c-Myc的表达。在具体目标1中，对 核因子-kappaB/Rel抑制因子的表达及其在细胞凋亡中的作用 将评估抗-IgM和CD40结扎后的I-kappaB-β。也是 转化生长因子-β1和β-1对I-kappaB-α转录诱导的调控 其通过CD40结扎持续减少的特征将被描述。在……里面 具体目标2，c-Myc水平下降在脑内的功能作用 将继续进行诱导细胞凋亡的工作。MYC已被证明可以诱导 E-box驱动启动子与其合作伙伴相互作用的转录 MAX，或抑制由INR元件驱动的基因转录。这个 调查人员已经确定了Max的另一份成绩单， 在B细胞中作为显性负MAX(DMAX)的蛋白质，它 抑制c-Myc反式激活。调查员提出了这样的表述 Dmax的作用是降低c-Myc在脑内的正向反式激活水平 不成熟的B细胞，c-Myc水平下降导致抑制 基因反式激活。因此，DMAX将被描述为：1)在 不同功能的B细胞阶段；2)作为一种负调控因子 C-Myc促进髓系细胞反式激活和凋亡； 关于c-Myc对INR介导的转录的抑制。最后， 由于MAX结合伙伴Mad1的表达是在以下条件下诱导的 WEHI 231细胞c-Myc表达下降并激活细胞凋亡 微量注射、MAD1表达的调控及其在细胞凋亡中的作用 将被描述为。总而言之，这些研究应该提供重要的 C-Myc癌基因和核因子-kappaB/Rel在乳腺癌中的作用 调控未成熟B细胞的凋亡和诱导耐受 克隆性删除。

DESCRIPTION (Adapted from the Applicant's abstract): The WEHI231 and CH33 immature B-cell lines have served extensively as models for the study of B-cell tolerance through clonal deletion via apoptosis. The investigator has recently shown that treatment of these lines with antisera against surface IgM or TGF-beta-1 leads to a reduction in activity of NF-kappaB/Rel transcription factors, causing a drop in c-myc expression which induces apoptosis. Rescue from apoptosis by CD40 ligation leads to maintenance of NF-kappaB/Rel and c-Myc expression. In Specific Aim 1, the regulation of expression and role in apoptosis of the NF-kappaB/Rel inhibitor I-kappaB-beta following anti-IgM and CD40 ligation will be assessed. Also the control of transcriptional induction of I-kappaB-alpha by TGF-beta-1 and of its sustained reduction by CD40 ligation will be characterized. In Specific Aim 2, the functional role of the drop in c-Myc levels in the induction of apoptosis will be pursued. Myc has been shown to either induce transcription of E-box driven promoters via interaction with its partner MAX, or to repress transcription of genes driven by Inr elements. The investigator has identified an alternate transcript of Max that generates protein functioning as a dominant negative Max (dMax) in B-cells, which inhibits c-Myc transactivation. The investigator proposes that expression of dMax serves to reduce the level of positive transactivation by c-Myc in immature B-cells, such that a drop in c-Myc levels results in de-repression of gene transactivation. Therefore, dMax will be characterized: 1) in different functional B-cell stages; 2) as a negative regulator of c-Myc-promoted transactivation and apoptosis in myeloid cells; and 3) with respect to c-Myc de-repression of Inr-mediated transcription. Finally, since expression of Mad1, the Max binding partner, was induced following the drop in c-Myc expression and activated apoptosis in WEHI 231 cells following microinjection, the regulation of Mad1 expression and its role in apoptosis will be characterized. Together, these studies should provide important insights into the role of the c-Myc oncogene and NF-kappaB/Rel in the control of apoptosis of immature B-cells and the induction of tolerance via clonal deletion.