Dual Role of RNA-binding Protein HuR in Binding mRNA and miRNA

Kumar, Ravi (2015) Dual Role of RNA-binding Protein HuR in Binding mRNA and miRNA. Masters thesis, Indian Institute of Science Education and Research Kolkata.

PDF (MS dissertation of Ravi Kumar) Ravi_Kumar_13IP024.pdf - Submitted Version Restricted to Repository staff only Download (1MB)

Abstract

RNA binding proteins having multiple binding domains could facilitate recognition of longer stretches of RNA along with recognition of binding sequences that are either separated via intervening stretches of nucleotides, or those belonging to different RNA molecules. HuR is a well known RNA binding protein having three RNA recognition motifs which generally known to binds with the UTR of mRNAs having an AU rich element (ARE). This helps in mRNA stability and rescue from translation inhibition by miRNAs. In our study, we focus on how different motifs of HuR are involve in binding with the 3’UTR of PDCD4 mRNA and its translation inhibitor miRNA miR-21. Our results suggest that RRM1 is the primary binding motif for the ARE within the 3’UTR PDCD4 mRNA whereas RRM2 shows much lower binding in comparison with RRM1, but when RRM2 together comes in play with RRM1, binding affinity increases up to ~7 fold with respect to individual RRM2. We have observed that RRM2 shows stronger binding affinity with miR-21 with respect to RRM1 and RRM3. Hence HuR being a multimeric modular protein exhibits its dual behaviour by utilising its various modules or motifs in which RRM1 appears to primary binding motif for the mRNA, whereas RRM2 appears to be the primary determinant for miRNA binding. The preliminary experiment of simultaneous binding ability of HuR to PDCD4 mRNA and miRNA suggests that as individual HuR molecule has role in binding to ARE containing mRNA and in sequestration of miRNA. Thereby it can rescue miRNA mediated translation inhibition much more rapidly under various stress responses. In future study we therefore will try to investigate the mechanism of binding of HuR to the ARE containing mRNA and miRNA using NMR based approach.

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