Poster abstracts

Poster number 144 submitted by Bing Zhang

Mechanistic Analysis of The Function of A Large Non-coding RNA

BING ZHANG (Department of Biochemistry, Case Western Reserve University), Lalith Gunawardane (Department of Biochemistry, Case Western Reserve University), Fereshteh Kenari , Saba Valadkhan (Department of Biochemistry, Case Western Reserve University)

Abstract:


The results of the ENCODE project and other large scale transcriptome analyses suggest that while over 75% of the human genome is transcribed into RNA, ORFs and their associated UTRs occupy only 2% of the genome. It is estimated that the human genome contains over 70,000 large non-protein coding transcripts (lncRNAs); however, many aspects of the biology and function of this novel class of cellular regulators are almost completely unknown.
We have analyzed a ~2700 nucleotide long nuclear transcript that is spliced and polyadenylated but has no protein-coding capacity. Interestingly, we found that the expression of the lncRNA is induced when cells are exposed to stressful conditions in several different cell types, including cells of mesodermal and ectodermal origin. We analyzed the expression of factors that are involved in cellular stress response and apoptosis in cells that either overexpressed the lncRNA or in which the RNA was knocked down using shRNA-mediated strategies. After exposure to stress, the knockdown cells exhibited an impaired cellular stress response and a much higher death rate compared to controls, while the overexpression cells showed an elevated level of stress response and a cellular stress-resistant phenotype. Analysis of the stress response factors indicated that some but not all heat shock proteins had a higher basal level in the overexpression cells even in the absence of stress and thus, the elevated expression of the lncRNA seemed to “pre-condition” the cells for tolerance of stress. Interestingly, in the knockdown cells, the induction of heat shock proteins after stress was both delayed and reduced in magnitude. We made a series of truncation mutations in the lncRNA and could show that deletion of part of the RNA close to its 5' end abolished its ability to impart stress resistance in transfected cells, while the other mutants did not have this effect. Together, these data indicate that this lncRNA plays an important role in regulation of the stress response and cellular survival under stressful conditions and demonstrates the power of lncRNAs as a novel class of regulatory molecules in higher eukaryotes.

Keywords: large non coding RNA, lncRNA, Stress