Budding yeast longevity

描述(申请人提供)：多细胞生物体的寿命依赖于组织动态平衡，而组织动态平衡又依赖于干细胞群体的持久性，这些干细胞群体处于静止状态，但保留了重新进入细胞周期自我更新的长期能力，或者产生能够分化和重新填充组织的后代。这些细胞从静止状态释放，或阻止它们进入静止状态，会导致不受控制的增殖和癌症。相反，静止细胞的丧失或无法重新进入细胞分裂，会扰乱器官发育，阻止老化细胞中的组织再生和修复。了解静止状态以及细胞如何控制进入和离开该状态的转换是至关重要的。然而，由于缺乏，我们对它知之甚少。 用于识别和研究处于自然环境中的静止细胞的工具。发芽酵母的静止状态与高等细胞有许多重要的特征，细胞周期从根本上是保守的。因此，逮捕和维持这种不分青红皂白的静止状态的战略很可能是共同的。我们建议识别影响静止酵母细胞的调节和寿命的基因，目的是为在更复杂的环境中定义静止提供工具和可测试的模型。以前关于酵母在不分裂状态下的寿命或时间老化的研究，都涉及监测固定相培养物的长期生存能力，但这些培养物在年龄和状态上都是不同的。我们已经证明，培养到稳定期的野生型酵母至少分化为三种细胞类型，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的细胞。这些技术进步使我们能够识别阻止或促进进入和维持静止状态的突变体和多态。我们可以监测衰老过程，并在同种年龄匹配的静止细胞群体中识别延长寿命的途径。我们在实验室和野生酵母菌株中观察到静止细胞的产量和寿命有相当大的差异。我们将利用这种变异和新的基因组学方法来识别影响静止细胞寿命或调节进入这种状态的基因和基因组。我们已经鉴定出野生二倍体酵母不能产生孢子但非常有效地进入静止期，反之亦然。这表明这些是不同的细胞命运，根据它们所处的环境，这些二倍体已经进化出调控障碍来指定路径选择。我们将利用这些极端的表型来识别这些调节者。我们希望，在发芽酵母中的发现将为调节后生动物细胞中的这些重要途径提供可测试的模型。

DESCRIPTION (provided by applicant): Longevity in multi-cellular organisms is dependent upon tissue homeostasis, which in turn depends on the persistence of stem cell populations that are quiescent, but retain the long-term 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 in aging cells. 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. The quiescent stateof 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. We propose to identify genes that influence the regulation and longevity of quiescent yeast cells with the goal of providing tools and testable models for defining quiescence in more complex settings. Previous studies of the longevity of yeast in the non-dividing state, or chronological aging, have all involved monitoring the long-term viability of stationary phase cultures, but these cultures are heterogeneous both in age and state. 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. These technical advances allow us to identify mutants and polymorphisms that prevent or promote entry and maintenance of the quiescent state. We can monitor the aging process and identify life-extending pathways in a homogenous population of age-matched quiescent cells. We have observed considerable variation in the yield and longevity of quiescent cells in lab and wild yeast strains. We will take advantage of this variatio and new genomic approaches to identify genes and groups of genes that influence the longevity of quiescent cells or regulate the entry into this state. We have identified wild diploid yeast tha fail to sporulate but enter quiescence very efficiently, and vice versa. This suggests that these are alternative cell fates and, depending on their environment, these diploids have evolved regulatory barriers to specify pathway choice. We will exploit these extreme phenotypes to identify these regulators. It is our hope that discoveries made in budding yeast will offer testabl models for the regulation of these important pathways in metazoan cells.