Faculty Responsibilities

Friday Seminar by Dr. Shivani Kansal


Speaker      :    Dr Shivani Kansal  

Topic           :  " To Hunt or To Tease…Factors regulating miRNA
                               targeting activity".
 
Date &         :    April 1, 2022
Time                 3.30 pm via online mode
Category: Research
Posted by: bedineel

To Hunt or To Tease…

Factors regulating miRNA targeting activity…

 

 miRNAs are short 21-24 nt RNA entities that are known as master regulators of post-transcriptional gene silencing. They are known to be architects across critical plant development stages and junctions as well shape stress responses under adverse conditions. miRNAs bind to a near-perfect complimentary site in the target mRNA and mediate their degradation via loading onto the AGO enriched-RISC complexes. However, what are the factors that actually tag an mRNA to be a target of a miRNA remains a mystery which is slowly being investigated and solved. In the past decade, individual research groups have established that presence of a near perfect complementary site is not the sole criteria for being a target of a miRNA. Li et al. 2014 and Zheng et al. 2017 show that the miRNA targeting activity is somewhat tolerant to central mismatches in the miRNA binding site, which earlier was considered as absolute deterrent for targeting. There are factors such as miRNA:mRNA stoichiometry, the sequence/site flanking the miRNA binding site, presence of RNA secondary structures upstream of miRNA binding site are some of the factors that fine tune the silencing activity of miR159. Ma et al, 2021 add to the information by describing that how regulation of miRNA accumulation itself is critical to its activity which is further governed at transcriptional and biogenesis levels. This mystery seems to have a very intricate network of factors that influence the miRNA activity which is now being described using the terms - ‘clearance’ or ‘rheostat’ modes of activity. 
 

References:

 

  • Li J, Reichel M, Millar AA (2014) Determinants beyond Both Complementarity and Cleavage Govern MicroR159 Efficacy in Arabidopsis. PLoS Genet 10(3): e1004232. doi:10.1371/journal.pgen.1004232
  • Zheng Z, Reichel M, Deveson I, Wong G, Li J, Millar AA. Target RNA Secondary Structure Is a Major Determinant of miR159 Efficacy. Plant Physiol. 2017 Jul;174(3):1764-1778. doi: 10.1104/pp.16.01898. Epub 2017 May 17. PMID: 28515145; PMCID: PMC5490886.
  • Ma X, Denyer T, Javelle M, Feller A, Timmermans MCP. Genome-wide analysis of plant miRNA action clarifies levels of regulatory dynamics across developmental contexts. Genome Res. 2021. 31: 811-822. doi:10.1101/gr.270918.120