REGULATION OF MITOGENIC CYTOKINE INDUCED APOPTOSIS

说明(改编自《调查者摘要》)。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。没有后者，进步就会通过 细胞周期会导致细胞凋亡。申请人已调查了 活化细胞与细胞增殖和凋亡的关系 有或无血清条件下的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， 几种类型的细胞经历了凋亡，这种现象被称为 细胞因子促进的凋亡(CPA)。有趣的是，在这个系统中，血清诱导 Bcl2等细胞生存基因的表达与促有丝分裂因子的关系 诱导bax、c-myc等促凋亡基因的表达 一份血清。通过用表达的cDNA文库转染细胞，然后 通过CPA和新霉素的双重选择，申请者已经确定了一部小说 细胞生存基因SRG-1。该基因位于人类1号染色体上 1p34-1p36.1，一个在许多细胞中参与肿瘤发生的位置 血统。SRG-1编码154个氨基酸的蛋白质。稳定 将SRG-1基因导入BAF/B03细胞，可产生对CPA的抗性。SRG-1也 抑制无血清成纤维细胞c-myc诱导的细胞凋亡。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，除了肝和脾。根据这些初步数据， 申请人建议确定注册会计师的基本机制，并 描述SRG-1在调节CPA中的作用。申请者假设 细胞因子诱导c-myc等基因表达，使细胞容易发生 增殖或发生细胞凋亡。最终结果取决于 激活细胞生存基因的第二信号的存在或不存在 Bc l-2和srg-1。为了检验这一假设，我们设计了以下目标：1) 申请者将确定c-myc、其上游房地产经纪人E2F1和a 下游目标cdc25A在CPA。这些基因将通过转染法进行调节。 在反义和显性负性形式的cdna的控制下 蜕皮激素诱导启动子。2)申请者将确定SRG-1的角色 通过检测其表达模式、细胞存活功能和 相互作用的蛋白质。拟议的实验的完成可能会改善 对细胞动态平衡调控的认识 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.