CELL CYCLE AND CELL DEATH STUDIES IN THE OCULAR LENS

眼透镜为研究细胞周期调控提供了一个理想的系统 终末分化。 透镜由两种单元类型组成： 能够进行细胞增殖的上皮细胞，以及 有丝分裂后的纤维细胞。 我假设 上皮细胞向纤维细胞的分化将导致 调节细胞周期的基因活性的改变。 在 为了帮助验证这一假设，将α A-晶状体蛋白启动子 用于指导转基因动物中基因表达的晶状体特异性改变， 小鼠 转基因和非转基因小鼠将用于研究两个 可能对细胞周期至关重要的基因的一般类别 分化过程中的控制：肿瘤抑制因子和细胞周期蛋白依赖性 激酶。 本申请的具体目的是：（1）评估 视网膜母细胞瘤（RB）蛋白在细胞周期控制中的作用， 透镜纤维细胞的终末分化; 2）评估p53的作用 在SV 4 O大T抗原诱导透镜肿瘤中的作用; 3）测定 伴随纤维细胞的细胞周期蛋白依赖性激酶的变化 分化; 4）表征由Rb诱导的细胞死亡 在纤维细胞中失活;和5）遗传逆转透镜 全长T抗原诱导的肿瘤发生。 我们的初步 实验表明，与Rb结合的病毒蛋白的表达 和/或p53可以诱导透镜细胞肿瘤发生或程序性细胞死亡。 因此，细胞周期可以在透镜细胞中改变， 和意想不到的后果。 拟议的研究应提供见解 进入细胞周期调节在体内，不仅为透镜，但为其他 经历终末分化或肿瘤转化的细胞。

The ocular lens provides an ideal system to study cell cycle regulation during terminal differentiation. The lens is composed of two cell types: the epithelial cells, which are capable of cellular proliferation, and the fiber cells, which are post-mitotic. I hypothesize that the differentiation of epithelial cells into fiber cells will cause alterations in activity of the genes that regulate the cell cycle. In order to help test this hypothesis, the alphaA-crystallin promoter will be used to direct lens-specific alterations in gene expression in transgenic mice. Transgenic and non-transgenic mice will be used to study two general classes of genes that are likely to be critical for cell cycle control during differentiation: tumor suppressors and cyclin-dependent kinases. The Specific Aims of this grant application are: l) to assess the role of the retinoblastoma (rb) protein in cell cycle control and terminal differentiation of lens fiber cells; 2) to assess the role of p53 in the induction of lens tumors by SV4O large T antigen; 3) to assay for changes in cyclin dependent kinases that accompany fiber cell differentiation; 4) to characterize the cell death that is induced by rb inactivation in fiber cells; and 5) to genetically reverse lens tumorigenesis induced by full-length T antigen. Our preliminary experiments have shown that expression of viral proteins that bind to rb and/or p53 can induce lens cell tumorigenesis or programmed cell death. Therefore, the cell cycle can be altered in lens cells with fascinating and unexpected consequences. The proposed studies should provide insights into cell cycle regulation in vivo, not only for the lens, but for other cells undergoing terminal differentiation or neoplastic transformation.