Natural Antisense Transcripts Mediate Discordant and Corcodant Regulation of Gene Expression
Mohammad Ali Faghihi and Claes Wahlestedt
from: Non-coding RNAs and Epigenetic Regulation of Gene Expression: Drivers of Natural Selection (Edited by: Kevin V. Morris). Caister Academic Press, U.K. (2012)
One prominent and complex class of regulatory RNAs is natural antisense transcripts. Natural antisense transcripts (also known as antisense RNAs or antisense transcripts) are RNA molecules that are transcribed from the opposite DNA strand and are often overlapping in part with mRNA of conventional sense genes. Transcription of antisense RNA, similar to sense RNA, is tissue and cell line specific. Indeed a large fraction of antisense transcripts is expressed in specific regions of the brain, supporting involvement of these regulatory RNAs in sophisticated brain functions as well as in complex neurological disorders. Recent research on natural antisense transcripts, including several large-scale expression-profiling studies, has conclusively established the existence of antisense transcripts in eukaryotic genomes. In fact, the consensus opinion is that natural antisense transcripts, most of which represent non-protein-coding RNAs, transcribed abundantly in the mammalian genome. However, there are many unanswered questions that still exist concerning antisense transcripts biological functions and their heterogeneous mode of actions in various cells. For instance, what fraction of antisense RNAs may have functional significance, and how many different regulatory mechanisms may exist for these RNA molecules? Natural antisense transcripts appear to be utilizing various cellular pathways, but it is still not clear which intrinsic properties of antisense RNA molecules or extrinsic features, such as protein interactions, cellular and developmental context are decisive for the selection of any given pathway. How is the expression of these non-protein-coding RNAs regulated in various cells, and what are the extrinsic factors that affect the transcription of antisense RNAs? Considering tissue- and cell type-specific expression patterns of antisense RNAs and their heterogeneous proposed functions, natural antisense transcripts appear to be a heterogeneous group of regulatory RNAs with a wide variety of biological roles read more ...