FUNCTION OF RAS ACTIVITY LATE IN THE CELL CYCLE

细胞ras和细胞周期蛋白D蛋白各自在细胞凋亡中发挥关键作用。 控制细胞增殖。 越来越多的证据表明， 这两个分子之间的重要联系。细胞外生长 信号控制ras活性，而ras活性刺激细胞周期蛋白D 程度. 这两种蛋白的功能是调节细胞周期进程 通过调节细胞周期控制蛋白的活性， GI期：当细胞向另一轮DNA做出承诺时 合成和细胞分裂。 我们现在报告ras和细胞周期蛋白D1可能参与了 在非预期的细胞周期点控制细胞周期进程; 晚期S期和G2期。 基于细胞周期分析程序 在对异步文化进行时间推移分析时， 定量荧光分析方法，我们在这里报告， 细胞周期蛋白D1在S期晚期和整个细胞周期中高水平表达， G2期。 在这项研究中，我们将测试我们的假设， 而细胞周期后期的细胞周期蛋白D表达可能在细胞周期中起着关键作用。 在控制细胞周期进程中的作用。 结论性地证明ras在晚期S-和G2- 阶段，ras活性将通过其与 靶肽。 在特定目标1中，信号通路 也将在细胞周期的后期分析ras的下游。 在具体目标2中，我们将确定ras活性的程度 导致细胞周期蛋白D1在细胞周期晚期表达， 比较ras活性与细胞周期蛋白D1 mRNA水平。 具体目标 3、ras活性和cyclin D1的生物学意义 将分析细胞周期后期的表达。 实验 旨在证明G2期产生的细胞周期蛋白D1 影响G1期细胞周期蛋白D1水平。 此外，我们将测试 细胞周期蛋白D1在有丝分裂前产生的可能性 影响进入静止和下一个G1的长度， 相位 这些研究有可能扩大我们的 理解ras活性在整个细胞中的作用 在细胞增殖的控制周期。

Cellular ras and cyclin D proteins each play critical roles in the control of cellular proliferation. Evidence increasingly indicates an important connection between these two molecules. Extra cellular growth signals control ras activity; while ras activity stimulates cyclin D levels. These two proteins function to regulate cell cycle progression by regulating the activity of cell cycle control proteins in late GI-phase; when the cell makes a commitment to another round of DNA synthesis and cell division. We now report the possible involvement of ras and cyclin D1 in the control of cell cycle progression at an unexpected cell cycle point; late S- and G2-phases. With a cell cycle analytical procedure based upon time lapse analysis of asynchronous cultures coupled with quantitative fluorescence analytical procedures, we report here that cyclin D1 is expressed at high levels late in S-phase and throughout G2-phase. In this study we will test our hypothesis that ras activity and cyclin D expression late in the cell cycle might play a critical role in the control of cell cycle progression. To conclusively demonstrate that ras is active in late S- and G2- phases, ras activity will be analyzed by its association with target peptides. In Specific Aim 1, the signaling pathway downstream of ras will also be analyzed late in the cell cycle. In Specific Aim 2, we will determine to what extent ras activity leads to cyclin D1 expression in late cell cycle stages by comparing ras activity to cyclin D1 mRNA levels. In Specific Aim 3, the biological importance of ras activity and cyclin D1 expression late in the cell cycle will be analyzed. Experiments are designed to demonstrate that cyclin D1 made in G2-phase effects cyclin D1 levels in G1 phase. In addition, we will test the possibility that cyclin D1 produced prior to mitosis influences entry into quiescence and the length of the next G1- phase. These studies have the potential to broaden our understanding of the role of ras activity throughout the cell cycle in the control of cellular proliferation.