饮食限制与延长寿命.ppt

1、饮食限制 与 延长寿命,生科一班 彭靓（1042041097）,什么是饮食限制？,饮食限制（Dietary restriction, DR） 是指限制食物摄入量至非随意摄入水平 而不会导致营养不良的状况。,The definition,什么是衰老？,衰老（ageing)是一个伴随着可能影响机体衰老的因素，如基因表达、染色体的稳定性、端粒的长度等的遗传性状态改变的过程。,The effect of DR,营养和应激感受器对饮食限制信号的反应能延长寿命，已在从酵母到灵长类的许多物种中均得以证明。 在动物模型中也证明 DR 可以延缓甚至完全避免年龄相关性疾病。包括心血管疾病、癌症、神经退行性病变和糖

2、尿病。短期 DR 还可降低人类发生冠心病和中风的危险。,The epigenetic mechanism,科学家于 1935 年首次报道适当限食可以延长大鼠寿限，迄今 70余年来, 大量实验已表明饮食限制是除遗传操控以外, 最强有力的延缓衰老方法。,Dietary restriction in yeast,Medium DR,What is Sir2?,Sir2, NAD+依赖的去乙酰化酶沉默信息调节子 2 Loss of this gene silencing effect results in sterility,which is a hallmark of ageing in yeast

3、. sir2,point towards activity concerned with modifying epigenetic markings. Sir2 also suppresses recombination at the ribosomal DNA locus,a process that,as cells age, leads to the accumulation of toxic extra-chromosomal ribosomal DNA circles,Severe DR,Dietary restriction in mammal,研究发现热量限制通过保持DNA修复酶

4、的完整对老年大鼠脑有神经保护作用, 并能上调与神经细胞死亡相关的抗凋亡蛋白的表达。,mammal Sirt1,沉默信息调节因子2相关酶1 Histone deacetylase Increased or retained DNA methylation Modulates chromatin stability and gene expression,Ageing is accompanied by changes to the epigenetic status of the genome that are known to influence factors of likely relev

5、ance to ageing such as gene expression ,genome stability and telomere length.,What is ageing?,What is ageing？,Based on the observation that the total methyl-cytosine(甲基胞嘧啶） content of DNA of mammalian cells decreased with time scientists proffered the view that this alteration in DNA methylation mig

6、ht explain reported changes in gene expression with age. Later studies have gone on to show that age-related demethylation(去甲基化） appears to be a passive process associated with attenuated（使减弱） activity of the maintenance DNA methylase DNMT1,which results from reduced expression. Loss of DNA methylation may contribute to genomic ins