FUNCTION OF RAS ACTIVITY LATE IN THE CELL CYCLE

细胞ras和细胞周期蛋白D在细胞周期调控中发挥重要作用。 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 级别。这两种蛋白质的功能是调节细胞周期进程。 通过调节晚期细胞周期控制蛋白的活性 Gi期；当细胞承诺另一轮DNA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 在一个意想不到的细胞周期点控制细胞周期进程； S晚期和G2期。基于细胞周期分析程序 基于时延分析的异步文化耦合 定量荧光分析程序，我们在此报告 细胞周期蛋白D1在S晚期和整个细胞中都有高水平的表达 G2期。在这项研究中，我们将检验我们的假设，即RAS活性 在细胞周期的晚期，细胞周期蛋白D的表达可能起到关键作用 在控制细胞周期进程中的作用。 为了确凿地证明RAS在S晚期和G2- 各阶段，RAS活动将通过其与 靶标多肽。在特定目标1中，信号通路 Ras下游也将在细胞周期的后期进行分析。 在具体目标2中，我们将确定RAS活动程度 通过以下途径导致细胞周期晚期细胞周期蛋白D1的表达 将ras活性与细胞周期蛋白D1mRNA水平进行比较。以特定的目标 3、ras活性和细胞周期蛋白d1的生物学意义 在细胞周期后期的表达将被分析。实验 旨在证明在G2期产生的细胞周期蛋白D1 对G1期细胞周期蛋白D1水平的影响。此外，我们还将测试 细胞周期蛋白D1在有丝分裂前产生的可能性 影响进入静止状态和下一个G1的长度- 相位。这些研究有可能扩大我们的 了解ras活性在整个细胞中的作用 控制细胞增殖的循环。

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.