C-MYC EXPRESSION AND APOPTOSIS IN A B CELL LINE

描述（改编自申请人的摘要）：WEHI 231和CH 33 不成熟的B细胞系已广泛用作研究 通过细胞凋亡通过克隆删除的B细胞耐受。 研究者 最近表明，用抗 表面IgM或TGF-β 1导致NF-κ B/Rel活性降低 转录因子，导致c-myc表达下降， 凋亡 通过CD 40连接拯救细胞凋亡导致维持细胞凋亡。 NF-κ B/Rel和c-Myc表达。 在具体目标1中， NF-kappaB/Rel抑制剂的表达及其在细胞凋亡中的作用 将评估抗IgM和CD 40连接后的I-kappaB-β。 也 TGF-β-1对I-κ B-α转录诱导的控制， 将表征其通过CD 40连接的持续降低。 在 具体目标2，c-Myc水平下降在肿瘤中的功能作用， 将继续进行细胞凋亡的诱导。 Myc已经被证明可以诱导 E-box驱动启动子通过与其配偶体相互作用的转录 MAX，或抑制由Inr元件驱动的基因的转录。 的 调查人员发现了麦克斯的另一份记录， 在B细胞中作为显性负Max（dMax）的蛋白质， 抑制c-Myc转录激活。 研究人员建议， dMax的作用是降低c-Myc的正反式激活水平， 不成熟的B细胞，使得c-Myc水平的下降导致去抑制 基因反式激活 因此，dMax将被表征为：1）在 不同功能性B细胞阶段; 2）作为 c-Myc-促进髓样细胞中的反式激活和凋亡;以及3） 关于Inr介导的转录的c-Myc去阻遏。 最后， 由于在诱导后诱导了Max结合配偶体Mad 1的表达， 在WEHI 231细胞中，C-Myc表达下降并激活凋亡， 显微注射，Mad 1的表达调控及其在细胞凋亡中的作用 将被定性。 总之，这些研究应该提供重要的 深入了解c-Myc癌基因和NF-κ B/Rel在 控制未成熟B细胞的凋亡和通过免疫调节诱导耐受 克隆缺失

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.