McCleary David F, Rine Jasper
Department of Molecular and Cell Biology, University of California at Berkeley, California 94720.
Department of Molecular and Cell Biology, University of California at Berkeley, California 94720
Genetics. 2017 Mar;205(3):1179-1193. doi: 10.1534/genetics.116.196485. Epub 2017 Jan 6.
Calorie restriction extends life span in organisms as diverse as yeast and mammals through incompletely understood mechanisms.The role of NAD-dependent deacetylases known as Sirtuins in this process, particularly in the yeast , is controversial. We measured chronological life span of wild-type and Δ strains over a higher glucose range than typically used for studying yeast calorie restriction. Δ extended life span in high glucose complete minimal medium and had little effect in low glucose medium, revealing a partial role for Sir2 in the calorie-restriction response under these conditions. Experiments performed on cells grown in rich medium with a newly developed genetic strategy revealed that Δ shortened life span in low glucose while having little effect in high glucose, again revealing a partial role for Sir2 In complete minimal media, Sir2 shortened life span as glucose levels increased; whereas in rich media, Sir2 extended life span as glucose levels decreased. Using a genetic strategy to measure the strength of gene silencing at , we determined increasing glucose stabilized Sir2-based silencing during growth on complete minimal media. Conversely, increasing glucose destabilized Sir-based silencing during growth on rich media, specifically during late cell divisions. In rich medium, silencing was far less stable in high glucose than in low glucose during stationary phase. Therefore, Sir2 was involved in a response to nutrient cues including glucose that regulates chronological aging, possibly through Sir2-dependent modification of chromatin or deacetylation of a nonhistone protein.
热量限制通过尚未完全了解的机制延长了从酵母到哺乳动物等多种生物的寿命。在这一过程中，被称为沉默调节蛋白的依赖烟酰胺腺嘌呤二核苷酸的脱乙酰酶的作用，尤其是在酵母中的作用，存在争议。我们在比通常用于研究酵母热量限制更高的葡萄糖范围内测量了野生型和Δ菌株的时序寿命。Δ在高葡萄糖完全基本培养基中延长了寿命，而在低葡萄糖培养基中影响很小，这揭示了在这些条件下Sir2在热量限制反应中的部分作用。用新开发的遗传策略对在丰富培养基中生长的细胞进行的实验表明，Δ在低葡萄糖条件下缩短了寿命，而在高葡萄糖条件下影响很小，这再次揭示了Sir2的部分作用。在完全基本培养基中，随着葡萄糖水平的升高，Sir2缩短了寿命；而在丰富培养基中，随着葡萄糖水平的降低，Sir2延长了寿命。使用一种遗传策略来测量在处基因沉默的强度，我们确定在完全基本培养基上生长期间，增加葡萄糖可稳定基于Sir2的沉默。相反，在丰富培养基上生长期间，尤其是在细胞后期分裂期间，增加葡萄糖会使基于Sir的沉默不稳定。在丰富培养基中，在稳定期高葡萄糖条件下的沉默远不如低葡萄糖条件下稳定。因此，Sir2参与了对包括葡萄糖在内的营养信号的反应，该反应可能通过Sir2依赖的染色质修饰或非组蛋白的去乙酰化来调节时序衰老。
