Long non-coding RNAs and enhancers.

Long non-coding RNAs (ncRNAs) are emerging as important regulatory factors in mammalian genomics. A number of reports within the last 2 years have identified thousands of actively expressed long ncRNA transcripts with distinct properties. The long ncRNAs show differential expression patterns and regulation in a w ide variety of cells and tissues, adding significant complexity to the understanding of their biological role. Furthermore, genome-wide studies of transcriptional enhancers based on chromatin modifications and enhancer binding proteins have led to the identification of putative enhancers and provided insight into their tissue-specific regulation of gene expression. In an exciting turn of events, new evidence is indicating that long ncRNAs are associated with enhancer regions and that such non-coding transcription correlate with the increased activity of the neighboring genes. Moreover, additional experiments suggest that enhancer-function can be mediated through a transcribed long ncRNA and that this might be a common function for long ncRNAs. Here, we review recent advances made both in the genome-wide characterization of enhancers and in the identification of new classes of long ncRNAs, and discuss the functional overlap of these two classes of regulatory elements.

长链非编码RNA（ncRNAs）在哺乳动物基因组学中逐渐成为重要的调控因子。过去两年内的大量报道已经鉴定出数千种具有独特性质的活跃表达的长链非编码RNA转录本。长链非编码RNA在多种细胞和组织中呈现出差异表达模式和调控，这大大增加了对其生物学作用理解的复杂性。此外，基于染色质修饰和增强子结合蛋白的转录增强子全基因组研究已经导致了假定增强子的鉴定，并为其组织特异性基因表达调控提供了见解。令人兴奋的是，新的证据表明长链非编码RNA与增强子区域相关，并且这种非编码转录与邻近基因活性的增加相关。此外，其他实验表明增强子功能可通过转录的长链非编码RNA介导，并且这可能是长链非编码RNA的一种常见功能。在此，我们综述了在增强子的全基因组特征描述以及新型长链非编码RNA的鉴定方面取得的最新进展，并讨论了这两类调控元件的功能重叠。