REGULATION OF MITOGENIC CYTOKINE INDUCED APOPTOSIS

描述（改编自研究者摘要）。细胞增殖需要 参与细胞周期进程的基因的协调激活以及 维持细胞活力的基因。如果没有后者， 细胞周期将导致细胞凋亡。申请人已调查 细胞增殖与凋亡的关系 促有丝分裂细胞因子和生长因子。 当在没有血清的情况下用细胞因子或生长因子刺激时， 几种细胞类型经历了凋亡，这种现象被称为 苦参碱促进细胞凋亡（CPA）。有趣的是，在这个系统中，血清诱导 细胞存活基因如bcl-2的表达，而促有丝分裂细胞因子 诱导促凋亡基因包括bax和c-myc的表达 血清。通过用表达cDNA文库筛选细胞，然后 通过CPA和新霉素的双重选择，申请人鉴定了一种新的 细胞存活基因SRG-1。该基因位于人类1号染色体上， 1 p34 -1p36.1，在许多细胞中与肿瘤发生有关的位置， 血统SRG-1编码154个氨基酸的蛋白质。稳定 转染SRG-1的BAF/B 03细胞对CPA具有抗性。SRG-1还 抑制c-myc驱动的血清剥夺成纤维细胞凋亡。SRG-1高度 在一些肿瘤和活化的T细胞中表达，但在大多数肿瘤中未检测到。 正常组织，除了肝脏和脾脏。根据这些初步数据， 申请人建议确定CPA的机制，并 描述SRG-1在调节CPA中的作用。申请人假设 细胞因子会诱导c-myc等基因的表达， 增殖或经历凋亡。最终结果取决于 存在或不存在激活细胞存活基因的第二信号， Bcl-2和SRG-1。以下目的是为了检验假设：1） 申请人将确定c-myc的作用，其上游Realtor E2 F1和 CPA中的下游靶标cdc 25 A。这些基因将通过转染进行调节 反义和显性负性形式的cDNA的控制下， 蜕皮激素诱导型启动子。2)申请人将确定SRG-1的作用 通过检测其表达模式，细胞存活功能， 相互作用的蛋白质完成拟议的实验可能会改善 对细胞内稳态调节的理解 炎症、发育、衰老和肿瘤发生。

DESCRIPTION (Adapted from Investigator's Abstract). Cell proliferation requires coordinated activation of genes involved in cell cycle progression as well as genes for maintaining cell viability. Without the latter, progression through the cell cycle will lead to apoptosis. The applicant has investigated the relationship between cell proliferation and apoptosis by activating cells with mitogenic cytokines and growth factors in the presence or absence of serum. When stimulated with cytokines or growth factors in the absence of serum, several cell types underwent apoptosis, a phenomenon referred to as cytokine-promoted apoptosis (CPA). Interestingly, in this system, serum induces expression of cell survival genes such as bcl-2 while mitogenic cytokines induce expression of pro-apoptotic genes including bax and c-myc in the absence of serum. By transfecting cells with an expression cDNA library, followed by double selection with CPA and neomycin, the applicant has identified a novel cell survival gene SRG-1. This gene is located on human chromosome 1 at 1p34-1p36.1, a location implicated in tumorigenesis in a number of cell lineages. SRG-1 encodes a putative protein of 154 amino acids. Stable transfection of SRG-1 to BAF/B03 cells confers resistance to CPA. SRG-1 also inhibits c-myc-driven apoptosis in serum-deprived fibroblasts. SRG-1 is highly expressed in some tumors and in activated T cells, but is not detected in most normal tissues, except liver and spleen. Based on these preliminary data, the applicant proposes to determine the mechanism underlying CPA and to characterize the role of SRG-1 in regulating CPA. The applicant hypothesizes that cytokines induce expression of genes like c-myc, which predispose cells to proliferation or undergo apoptosis. The ultimate outcome is determined by the presence or absence of second signals which activate cell survival genes such as Bcl-2 and SRG-1. The following aims are designed to test the hypothesis: 1) The applicant will establish the role of c-myc, its upstream Realtor E2F1 and a downstream target cdc25A in CPA. These genes will be modulated by transfection of the cDNA in anti-sense and dominant negative forms under the control of the ecdysone-inducible promoter. 2) The applicant will determine the role of SRG-1 in CPA by examining its expression pattern, cell survival functions, and interacting proteins. The completion of the proposed experiments may improve the understanding of the regulation of cellular homeostasis during inflammation, development, aging and tumorigenesis.