Poster abstracts

Poster number 57 submitted by Justin Pruttivarasin

Large non-coding RNAs: a diverse, evolutionarily young group of transcripts.

Justin Pruttivarasin (Center for RNA Molecular Biology, Case Western Reserve University), Faiza N. Khimji (Georgetown University), Saba Valadkhan (Center of RNA Molecular Biology, Case Western Reserve University)

Abstract:
The function of large non-protein-coding RNAs (ncRNA) has remained largely unknown, but they are thought to play important roles in generating the complexity seen in higher eukaryotes. We are interested in defining the rules that govern the mechanism of function of large non-coding RNAs, since despite a number of recent studies, very little is known about the mechanistic aspects of their function. In order to tackle this question, we created a database of more than one hundred large ncRNAs for which at least a general function has been described. Using bioinformatics analysis tools, we searched for sequence elements in the ncRNAs which might be important for their function, such as the presence of transposable elements, small opening reading frames, microRNA precursors, and the levels of conservation. We also determined if any of these RNAs overlapped in sense or antisense direaction with any known genes. Strikingly, over 20% of the transcripts described as large ncRNAs in the database contain hairpins identical to known miRNA precursors in their exons or introns. In some cases, alternatively splicing leads to removal or inclusion of a miRNA precursor sequence. Interestingly, some ncRNAs contain different miRNA precursors for different alternatively spliced isoforms. About 70% of ncRNAs in the database contain transposable elements (TE). While for most ncRNAs, TEs amount to 10-50% of their sequence, for some the share of TEs can reach as high as 70%, consistent with the rapid evolution of this class of transcripts. About 46% of the ncRNAs contain one or more opening reading frames of greater than 300 nucleotides. Close to 30% of the studied ncRNAs were at least partially antisense to a known transcript. Work is underway to further analyze the various features of known ncRNAs. Ultimately, the insights gained from this study will lead to the development of a functional classification system for these mysterious, novel class of cellular regulators.

Keywords: non-coding RNAs