Intergenic IncRNAs and the evolution of gene expression

Eukaryote genomes encode a surprisingly large number of noncoding transcripts. Around two-thirds of human transcribed loci do not encode protein, and many are intergenic and produce long (>200 nucleotides) noncoding RNAs (IncRNAs). Extensive analyses using comparative genomics and transcriptomics approaches have established that IncRNA sequence and transcription tend to turn over rapidly during evolution. Our appreciation of the biological roles of IncRNAs, based only on a handful of transcripts with well-characterized functions, is that IncRNAs have diverse roles in regulating gene expression. These proposed roles together with their rapid rates of evolution suggest that IncRNAs could contribute to the divergent expression patterns observed among species and potentially to the origin of new traits.