CONTROL OF CELL PROLIFERATION

所有真核细胞的增殖主要受一种 发生在细胞周期的G1期的单一决定--或者 完成细胞周期并分裂或退出细胞周期 并进入静止状态。在正常细胞中，这一决定是受调节的 通过特定的细胞内和细胞外信号，如有丝分裂 增长因素。然而，在转化或致瘤的细胞中，这些 对照被抑制，细胞增殖不受限制。重要 最近，在理解分子基础方面取得了进展。 这一关键的监管过程。在酿酒酵母中，这个决定是 称为Start的开始和完成最终导致DNA复制和 委托细胞完成细胞分裂周期的剩余部分。这个 这一细胞决定的基础是生物化学事件 和激活由CDC28编码的蛋白激酶之间的复合体 基因，和一个积极作用的调节亚基的激酶，细胞周期蛋白。 努力了解控制病毒的分子基础 因此，哺乳动物细胞的增殖最近集中在 这一蛋白激酶家族被称为细胞周期蛋白依赖性激酶，并且 他们的监管者，Cyclins。我们分离出一种新的人类细胞周期蛋白--细胞周期蛋白 E.基于其在功能上替代酿酒酵母的能力 G1期细胞周期蛋白。我们通过生化和生理检测发现， 它可能在调节G1期的增殖方面起着重要作用 哺乳动物细胞周期的阶段--1)Cyclin E结合并激活 细胞周期蛋白依赖性激酶在人类细胞G1期的特异性 2)细胞周期蛋白E在原代人成纤维细胞中的组成表达 加速G1、缩小细胞大小并降低对生长因子的需求 用于细胞增殖；3)在G1中抑制细胞周期的两个因素， 雷帕霉素和转化生长因子-β阻断细胞周期蛋白B/激酶复合体的激活。 我们的总体目标是更全面地了解 细胞周期蛋白E在衰老过程中的生理生化和分子作用 哺乳动物的细胞周期，包括成纤维细胞和淋巴细胞，以及 了解这些操作如何有助于控制细胞 扩散。我们的具体方法将包括分析 结构性细胞周期蛋白E的表达及其抑制的生理效应 细胞周期蛋白E的表达对哺乳动物细胞周期的调控； 用高分辨率双向凝胶电泳法研究细胞周期依赖性 细胞周期蛋白E的修饰及其与细胞周期的相互作用 B与其他蛋白质的相互作用；以及与细胞周期蛋白的生理作用相关 用细胞周期蛋白E分析其分子和生化特性 突变。

The proliferation of all eukaryotic cells is primarily controlled by a single decision which occurs in the G1 phase of the cell cycle -- either to complete the cell cycle and divide or to withdraw from the cell cycle and enter a quiescent state. In normal cells this decision is regulated by specific intracellular and extracellular signals, such as mitogenic growth factors. In transformed or tumorigenic cells, however, these controls are suppressed and cell proliferation is unconstrained. Important advances have been made recently in understanding the molecular basis for this critical regulatory process. In S. cerevisiae, this decision is called START and completion of START culminates in DNA replication and commits the cell to complete the remainder of the cell division cycle. The biochemical event that underlies this cellular decision is the assembly and activation of complex between a protein kinase, encoded by the CDC28 gene, and a positively acting regulatory subunit of the kinase, a cyclin. Efforts to understand the molecular basis for controlling the proliferation of mammalian cells, therefore, have recently focused upon this family of protein kinases, named the cyclin-dependent kinases, and their regulators, the cyclins. We have isolated a new human cyclin, cyclin E, based upon its ability to functionally substitute for the S. cerevisiae G1 cyclins. We have found, by biochemical and physiological assays, that it probably plays a major role in regulating proliferation during the G1 phase of the mammalian cell cycle --1) Cyclin E binds to and activates a cyclin-dependent kinase specifically during the G1 phase of the human cell cycle; 2) Constitutive expression of cyclin E in primary human fibroblasts accelerates G1, reduces cell size and decreases growth factor requirements for cell proliferation; 3) Two factors that inhibit the cell cycle in G1, rapamycin and TGF-beta, block activation of the cyclin B/kinase complex. Our general goal is to develop a more complete picture of the physiological, biochemical and molecular actions of cyclin E during the mammalian cell cycle, both in fibroblasts and lymphocytes, and to understand how these actions contribute to the control of cell proliferation. Our specific approaches will include analyzing the physiological effects of constitutive cyclin E expression and inhibition of cyclin E expression on regulation of the mammalian cell cycle; studying, by high resolution two dimensional PAGE, cell cycle dependent modifications of cyclin E and cell cycle dependent interactions of cyclin B with other proteins; and correlating the physiological actions of cyclin B with its molecular and biochemical properties by analysis of cyclin E mutations.