Effects of cis and trans regulatory variations on the expression divergence of heat shock response genes between yeast strains

Phenotypic variation among individuals in a population can be due to DNA sequence variation in protein coding regions or in regulatory elements. Recently, many studies have indicated that mutations in regulatory elements may be the major cause of phenotypic evolution. However, the mechanisms for evolutionary changes in gene expression are still not well understood. Here, we studied the relative roles of cis and trans regulatory changes in Saccharomyces cerevisiae cells to cope with heat stress. It has been found that the expression level of ~ 300 genes was induced at least two fold and that of ~ 500 genes was repressed at least two fold in response to heat shock. From the former set of genes, we randomly selected 65 genes that showed polymorphism(s) between the BY and RM strains for pyrosequencing analysis to explore the relative contributions of cis and trans regulatory variations to the expression divergence between BY and RM. Our data indicated that the expression divergence between BY and RM was mainly due to trans regulatory variations under either the normal condition or the heat stress condition. However, the relative contribution of trans regulatory variation was decreased from 76.9% to 61.5% after the heat shock stress. These results indicated that the cis regulatory variation may play an important role in the adaption to heat stress. In our data, 43.1% (28 genes) of the 65 genes showed the same trend of cis or trans variation effect after the heat shock stress, 35.4% (23 genes) showed an increased cis variation effect and 21.5% (14 genes) showed an increased trans variation effect after the heat shock stress. Thus, our data give insights into the relative roles of cis and trans variations in response to heat shock in yeast.     

转录组与蛋白质组比较研究进展

转录组和蛋白质组比较研究发现,总体而言其间的相关性不高 . 根据数据的类型不同可以将现有的研究分为 4 类：单点比较、两点差异比较、多点时序比较和多点非时序比较 . 对其差异原因的研究和分析表明：除了由实验系统及数据类型不同导致的差异外,转录后蛋白质合成各步骤所受到的限制,以及在此过程中的分子调控也对其有重要的影响;而且不同基因,不同组织和细胞在不同状态下可能也会有差异 . 因此,结合转录组和蛋白质组的表达谱研究倾向于利用蛋白质组和转录组研究的差异和互补性,同时对生物体特定状态下的基因和蛋白质表达水平进行全方位度量,以获得表达谱的全景图,并挖掘受到转录后调控的基因 .