Expression data from Saccharomyces cerevisiae. Saccharomyces cerevisiae

Alzheimer’s disease (AD) is a progressive neurodegenerative disorder. Oligomers of Amyloid-β peptides (Aβ) are thought to play a pivotal role in AD pathogenesis, yet the mechanisms involved remain unclear. Two major isoforms of Aβ associated with AD are Aβ40 and Aβ42, the latter being more prone to form oligomers and toxic. Humanized yeast models are currently applied to unravel the cellular mechanisms behind Aβ toxicity. Here, we took a systems biology approach to study two yeast AD models which expressed either Aβ40 or Aβ42 in bioreactor cultures. Strict control of oxygen availability and culture pH, strongly affected the chronological lifespan and reduced confounding effects of variations during cell growth. Reduced growth rates and biomass yields were observed upon expression of Aβ42, indicating a redirection of energy from growth to maintenance. Quantitative physiology analyses furthermore revealed reduced mitochondrial functionality and ATP generation in Aβ42 expressing cells, which matched with observed aberrant fragmented mitochondrial structures. Genome-wide expression levels analysis showed that Aβ42 expression triggers strong ER stress and unfolded protein responses (UPR). Expression of Aβ40 induced only mild ER stress, leading to activation of UPR target genes that cope with misfolded proteins, which resulted in hardly affected physiology. The combination of well-controlled cultures and AD yeast models strengthen our understanding of how cells translate different levels of Aβ toxicity signals into particular cell fate programs, and further enhance their role as a discovery platform to identify potential therapies. Overall design: The goal of the present study is to evaluate the impact of Aβ peptides expression on yeast physiology and transcriptome profiles following the growth phases. Saccharomyces cerevisiae expressing Aβ42 and Aβ40 peptide respectively was cultivated in well controlled bioreactors. Samples were taken from duplicate cultures during exponential phase (EX), post-diauxic shift phase (PD), early stationary phase (SP1), late stationary phase (SP2).

阿尔茨海默病（Alzheimer’s disease, AD）是一种进行性神经退行性疾病。β淀粉样肽（Amyloid-β peptides, Aβ）寡聚体被认为在AD发病机制中发挥关键作用，但其相关作用机制仍未阐明。与AD密切相关的Aβ主要存在两种同工型：Aβ40与Aβ42，其中Aβ42更易形成寡聚体且毒性更强。目前，人源化酵母模型被广泛用于解析Aβ毒性的细胞内机制。本研究采用系统生物学策略，对生物反应器培养体系中分别表达Aβ40与Aβ42的两款AD酵母模型开展研究。通过严格调控氧供给与培养液pH，我们精准控制了酵母的时序寿命，并大幅降低了细胞生长过程中变量带来的混杂效应。表达Aβ42的酵母菌株的生长速率与生物量产量均显著下降，提示细胞将能量代谢从增殖生长重定向至基础维持过程。定量生理学分析进一步显示，表达Aβ42的细胞线粒体功能与ATP生成能力均出现损伤，这与观测到的线粒体结构异常碎裂表型高度吻合。全基因组表达谱分析表明，Aβ42的表达会触发强烈的内质网应激（ER stress）与未折叠蛋白反应（unfolded protein responses, UPR）；而Aβ40的表达仅引发轻度内质网应激，仅激活负责清除错误折叠蛋白的UPR靶基因，因此其生理状态几乎未受明显影响。本研究结合了标准化可控培养体系与AD酵母模型，深化了我们对细胞如何将不同水平的Aβ毒性信号转化为特定细胞命运程序的认知，同时进一步凸显了该模型作为潜在治疗靶点发现平台的应用价值。整体实验设计：本研究旨在评估Aβ肽表达对酵母生理学特性与转录组谱的影响，采样覆盖酵母全部生长阶段。将分别表达Aβ42与Aβ40的酿酒酵母（Saccharomyces cerevisiae）置于严格可控的生物反应器中培养，从重复培养的样本中分别于指数生长期（EX）、二次生长转变后阶段（PD）、早期稳定期（SP1）与晚期稳定期（SP2）进行采样。