Cell Cycle Re-entry from quiescence

项目总结/摘要 多细胞生物体的发育、组织更新和长期存活取决于 干细胞的持久性是静止的，但保留重新进入细胞周期自我更新的能力，或 产生可以分化和重新填充组织的后代。这些细胞的释放失调， 静止状态或阻止它们进入静止状态，导致不受控制的增殖和癌症。 相反，失去静止细胞或它们不能重新进入细胞分裂，会破坏器官发育， 阻止组织再生和修复。了解静止状态以及细胞如何控制 在这种状态中的转换和从这种状态中的转换具有根本的重要性。然而，我们对它的了解相对较少，由于 缺乏在自然环境中识别和研究静止细胞的工具。我们建议确定 影响芽殖酵母细胞进入、维持和从静止状态恢复的基因。的 芽殖酵母的静止状态与高等细胞的静止状态有许多共同的重要特征， 基本上是保守的。因此，阻止和维持这种不分裂的静止状态的策略 国家很可能是共享。进入静止期需要G1期稳定但可逆的停滞。我们 定义这种G1停滞的机制，正如预期的那样，我们发现与过渡到 在高等细胞中静止。使用流式细胞术，我们已经表明野生型酵母生长到静止 在第一阶段，细胞分化成至少三种细胞类型，其中只有一种具有静止细胞的特性。我们 可以追踪、量化和纯化这些静止细胞。我们已经观察到产率的相当大的变化， 实验室和野生酵母菌株中静止细胞的寿命。我们正在利用这种自然变异， 新的基因组方法来确定多态性的必需和非必需基因，影响 长寿的静止细胞或调节进入这种状态。我们希望在萌芽中的发现 酵母将为后生动物细胞中这些重要途径的调节提供可测试的模型。

Project Summary/Abstract Development, tissue renewal and long term survival of multi-cellular organisms is dependent upon the persistence of stem cells that are quiescent, but retain the capacity to re-enter the cell cycle to self-renew, or to produce progeny that can differentiate and re-populate the tissue. Deregulated release of these cells from the quiescent state, or preventing them from entering quiescence, results in uncontrolled proliferation and cancer. Conversely, loss of quiescent cells, or their failure to re-enter cell division, disrupts organ development and prevents tissue regeneration and repair. Understanding the quiescent state and how cells control the transitions in and out of this state is of fundamental importance. And yet, we know relatively little about it, due to a lack of tools for identifying and studying quiescent cells in their natural setting. We propose to identify genes that influence the entry, maintenance and recovery from the quiescent state in budding yeast cells. The quiescent state of budding yeast shares many important features with that of higher cells and the cell cycle is fundamentally conserved. As such, the strategies for arresting and maintaining this non-dividing quiescent state are likely to be shared. Entry into quiescence requires a stable but reversible arrest in G1. We are defining the mechanism of this G1 arrest and, as expected, we find striking parallels with the transition to quiescence in higher cells. Using flow cytometry, we have shown that wild type yeast grown to stationary phase differentiate into at least three cells types, only one of which bears the properties of quiescent cells. We can track, quantify and purify these quiescent cells. We have observed considerable variation in the yield and longevity of quiescent cells in lab and wild yeast strains. We are taking advantage of this natural variation and new genomic approaches to identify polymorphisms in essential and non-essential genes that influence the longevity of quiescent cells or regulate the entry into this state. It is our hope that discoveries made in budding yeast will offer testable models for the regulation of these important pathways in metazoan cells.