Discovery of genes that extend yeast lifespan: Aging in immobilized cell reactors

发现延长酵母寿命的基因：固定化细胞反应器中的老化

• 批准号: 7897590
• 负责人: Raphael F Rosenzweig
• 金额: $ 13.6万
• 依托单位: UNIVERSITY OF MONTANA
• 依托单位国家: 美国
• 财政年份: 2009
• 资助国家: 美国
• 起止时间: 2009-08-13 至 2011-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/7897590
• 关键词: Age; Aging; Alginates; Biology of Aging; Biomass; Bioreactors; Caloric Restriction; Cell Aging; Cell Maintenance; Cell division; Cells; Collection; Data; Environment; Ethanol; Eukaryota; Fellowship; Gene Deletion; Gene Expression; Genes; Genetic; Genetic Determinism; Genetic Screening; Genomics; Homologous Gene; Human; Immobilization; Immobilized Cells; Individual; Interphase Cell; Investigation; Life; Longevity; Mammals; Metabolic; Metabolism; Microbe; Mothers; Mutation; Nutrient; Pathway interactions; Phase; Physiological; Play; Population; Proteins; Quality of life; Relative (related person); Reproduction; Resistance; Resources; Role; Saccharomyces cerevisiae; Solid; Stress; System; Time; Yeasts; cell age; cell growth; feeding; gene discovery; improved; insight; longevity gene; member; mutant; sugar; symposium; tool

DESCRIPTION (provided by applicant): - Many of our deepest insights into the biology of aging have been gained using the simple Eukaryote Saccharomyces cerevisiae. Foundational studies using yeast have led to the discovery of the role played by the silent information regulator protein Sir2 in modulating replicative lifespan, and the roles played by Ras2, Cyr1 and Sch9 in modulating chronological lifespan. Each of these genes has a homologue with similar function in higher Eukaryotes, including mammals. These discoveries have generated excitement about the prospects for extending lifespan and improving quality of life for older members of the human population. To date, all investigations into the genetic mechanisms that extend chronological lifespan in yeast have focused on the viability of non-growing planktonic cells in stationary-phase batch culture. There, cells enter a physiological state where metabolism is reprogrammed to efficiently use stored resources for the purpose of cell maintenance. Not surprisingly, screens for mutants which alter chronological lifespan under these conditions have produced a collection of genes whose activities influence resistance to stress. But yeast populations largely cease to reproduce in another, very different environmental context. Continuously or semi-continuously fed bioreactors populated by yeast immobilized in semi-solid beads can be maintained for weeks, or even months. These reactors continue to produce close-to-theoretical yields of ethanol but very little biomass, relative to substrate input. Herein, we present demographic, physiological and genomic data that illuminate features of the immobilized state, features that we contend make this system ideally suited for the study of chronological aging. We propose to follow on from these results with an investigation into the mechanism(s) that enable yeast to live for extended periods of time in a calorically un-restricted environment wherein metabolic flux appears to be maximized at the expense of cell growth and reproduction. The Specific Aims of this investigation are threefold; we will: (1) Determine in wild-type yeast whether long-term immobilization alters chronological lifespan and global gene expression relative to aging planktonic cultures; (2) Establish, relative to wild-type, whether mutations known to alter both replicative and chronological lifespan in planktonic cells produce similar alterations in aging immobilized cells. (3) Conduct a large-scale genetic screen of single-gene-deletion yeast strains cultured in the immobilized and planktonic states (a) to discover new classes of longevity genes that act in undescribed pathways, and (b) to establish whether there are common determinants of chronological longevity under calorically-restricted and non-calorically-restricted conditions. PROJECT NARRATIVE - Many of our deepest insights into the biology of aging have been gained using the simple microbe, Bakers yeast. Individual yeast cells have a finite lifespan, and they age in two ways: mother cells age as they undergo successive rounds of cell division; non-dividing cells also age and eventually die. Caloric restriction appears to extend lifespan in all species studied, including yeast. But controversy surrounds the issue of whether caloric restriction is a proximal or ultimate cause of longevity. To date, all studies on the genetics on non-dividing cells have imposed caloric restriction, making this variable impossible to tease out. Yeast can be confined within semi-solid alginate beads and exposed to excess nutrients. There, they convert sugar to ethanol at extremely high rates, but do so with little or no cell division. We will exploit this system as a tool to discover whether lifespan extension is possible under calorically non- restrictive conditions, and if so, we aim to discover underlying genetic determinants.

描述（由申请人提供）：-我们对衰老生物学的许多最深刻的见解都是使用简单的真核酵母酿酒酵母获得的。使用酵母的基础研究发现了沉默信息调节蛋白Sir 2在调节复制寿命中所起的作用，以及Ras 2，Cyr 1和Sch 9在调节时序寿命中所起的作用。这些基因中的每一个在高等真核生物（包括哺乳动物）中具有类似功能的同源物。这些发现使人们对延长寿命和改善老年人生活质量的前景感到兴奋。到目前为止，所有的调查遗传机制，延长时间的寿命在酵母集中在非生长的增殖细胞在静止期分批培养的活力。在那里，细胞进入一种生理状态，其中新陈代谢被重新编程，以有效地利用储存的资源来维持细胞。毫不奇怪，在这些条件下筛选出的改变时间寿命的突变体已经产生了一系列基因，这些基因的活性影响了对压力的抵抗力。但是酵母菌群在另一个非常不同的环境中基本上停止繁殖。由固定在半固体珠中的酵母填充的连续或半连续进料的生物反应器可以维持数周或甚至数月。这些反应器继续产生接近理论产率的乙醇，但相对于底物输入，生物质非常少。在此，我们提出了人口统计学，生理学和基因组数据，阐明了固定状态的特征，我们认为这些特征使该系统非常适合于时间老化的研究。我们建议从这些结果中继续研究使酵母能够在热量不受限制的环境中长时间存活的机制，其中代谢通量似乎以细胞生长和繁殖为代价而最大化。本研究的具体目的有三个：（1）确定野生型酵母中长期固定是否会改变相对于老化的增殖培养物的时间寿命和整体基因表达;（2）确定相对于野生型，已知改变增殖细胞中复制和时间寿命的突变是否会在老化的固定细胞中产生类似的改变。(3)对在固定和非固定状态下培养的单基因缺失酵母菌株进行大规模遗传筛选，（a）以发现在未描述的途径中起作用的新类型的长寿基因，和（B）以确定在热量限制和非热量限制条件下是否存在时间寿命的共同决定因素。 项目叙述-我们对衰老生物学的许多最深刻的见解都是使用简单的微生物，面包酵母。单个酵母细胞的寿命是有限的，它们以两种方式衰老：母细胞随着连续几轮的细胞分裂而衰老;非分裂细胞也会衰老并最终死亡。 热量限制似乎延长了所有研究物种的寿命，包括酵母。但是，围绕热量限制是否是长寿的近端或最终原因的问题存在争议。到目前为止，所有关于非分裂细胞遗传学的研究都对热量进行了限制，使得这个变量不可能梳理出来。 酵母可以被限制在半固体藻酸盐珠中并暴露于过量的营养物中。在那里，它们以极高的速度将糖转化为乙醇，但几乎没有细胞分裂。我们将利用这一系统作为一种工具，以发现在热量非限制性条件下是否有可能延长寿命，如果有，我们的目标是发现潜在的遗传决定因素。