Poster abstracts
Poster number 146 submitted by Megan Westwood
Investigating structural features of pre-miR-122 that affect Dicer processing
Megan N. Westwood (Biophysics, University of Michigan), Sarah C. Keane (Biophysics, University of Michigan)
Abstract:
Proper cellular function depends on both protein coding and non-coding (nc) RNAs. Mature microRNAs (miRNAs) play a critical role in post-transcriptional regulation of gene expression, regulating more than half of human messenger RNAs. MiRNAs are transcribed from DNA into primary (pri-) miRNAs which are processed in the nucleus to make precursor (pre-) miRNAs. Subsequent cytoplasmic processing of pre-miRNAs involves Dicer and transactivation response element RNA-binding protein (TRBP) to produce mature miRNAs. Pre-miR-122 is a tissue-specific miRNA that is highly expressed in the liver and aberrant expression of miR-122 is a hallmark of various tumors and cancers including hepatocellular carcinoma. Pre-miR-122 has no known RNA-binding proteins that modulate its biogenesis post-transcriptionally. Therefore, pre-miR-122 may possess intrinsic structural properties that regulate its processing. To gain atomic-level insight into the structure(s) of pre-miR-122, I will use nuclear magnetic resonance (NMR) spectroscopy. Interestingly, secondary structure predictions and NOEs observed near the apical loop suggest that pre-miR-122 may adopt alternative conformations. Comparative processing assays with Dicer:TRBP between the wildtype and mutant RNAs, designed to stabilize specific alternative structures, will be used to assess which structural features regulate its biogenesis. Future work will include using NMR dynamics experiments to quantify the populations and rate constants of conformational exchange. Together, this work will provide unprecedented insight into the structural and dynamic features of pre-miR-122 to understand how its biogenesis is regulated post-transcriptionally.
Keywords: microRNA