Bar-Even Arren, Paulsson Johan, Maheshri Narendra, Carmi Miri, O'Shea Erin, Pilpel Yitzhak, Barkai Naama
Department of Molecular Genetics, Weizmann Institute of Science, Rehovot 76100, Israel.
Nat Genet. 2006 Jun;38(6):636-43. doi: 10.1038/ng1807. Epub 2006 May 21.
Noise in gene expression is generated at multiple levels, such as transcription and translation, chromatin remodeling and pathway-specific regulation. Studies of individual promoters have suggested different dominating noise sources, raising the question of whether a general trend exists across a large number of genes and conditions. We examined the variation in the expression levels of 43 Saccharomyces cerevisiae proteins, in cells grown under 11 experimental conditions. For all classes of genes and under all conditions, the expression variance was approximately proportional to the mean; the same scaling was observed at steady state and during the transient responses to the perturbations. Theoretical analysis suggests that this scaling behavior reflects variability in mRNA copy number, resulting from random 'birth and death' of mRNA molecules or from promoter fluctuations. Deviation of coexpressed genes from this general trend, including high noise in stress-related genes and low noise in proteasomal genes, may indicate fluctuations in pathway-specific regulators or a differential activation pattern of the underlying gene promoters.
基因表达中的噪声在多个层面产生，如转录和翻译、染色质重塑以及特定途径的调控。对单个启动子的研究表明了不同的主要噪声来源，这就提出了一个问题，即在大量基因和条件下是否存在普遍趋势。我们检测了在11种实验条件下生长的细胞中43种酿酒酵母蛋白质的表达水平变化。对于所有类型的基因以及在所有条件下，表达方差大致与均值成正比；在稳态和对扰动的瞬态响应过程中也观察到了相同的比例关系。理论分析表明，这种比例行为反映了mRNA拷贝数的变异性，这是由mRNA分子的随机“产生和消亡”或启动子波动导致的。共表达基因偏离这一普遍趋势，包括应激相关基因中的高噪声和蛋白酶体基因中的低噪声，可能表明特定途径调节因子的波动或潜在基因启动子的差异激活模式。
