Tissue-specific evolutionarily conserved regulation of gene expression

实际上，多细胞生物体中的每个细胞都含有相同的DNA基因组，但每种细胞类型的外观和功能都不同，以履行其在有机体中所需的角色。正是基因组中每个基因在每种细胞类型中表达方式的不同，解释了细胞功能的巨大差异。尽管经过数百万年的进化，脊椎动物的外表千差万别，但它们基本上是由相似的细胞类型和器官组成的。来自不同脊椎动物物种的大脑、肝脏和心脏在同一器官内的共同基因表达多于同一物种内不同器官之间的基因表达。这种共性表明，在每个组织中调节基因表达的机制在进化过程中是高度保守的。然而，我们缺乏对这些机制的了解，也无法准确定位基因组中大多数不在基因中但负责这种非凡的保护的区域。

Virtually every cell in a multicellular organism contains the same DNA genome yet each celltype looks and functions differently to perform its required role in the organism. It is the differences in the way each gene in the genome is expressed in each cell type that accounts for these dramatic differences in cellular functions. Even though there is a wide variety in appearance between vertebrates separated by millions of years of evolution, they are fundamentally made up of similar cell-types and organs. Brain, liver and heart from different vertebrate species share more common gene expression within the same organ than between different organs within the same species. This commonality indicates that the mechanisms that regulate gene expression in each tissue are highly conserved through evolution. We lack, however, an understanding of these mechanisms and are not able to pinpoint most of the regions of the genome that are not in genes, but that are responsible for this remarkable conservation.