AUTHOR=Pandey Manish , Luhur Arthur , Sokol Nicholas S. , Chawla Geetanjali 

TITLE=Molecular Dissection of a Conserved Cluster of miRNAs Identifies Critical Structural Determinants That Mediate Differential Processing

JOURNAL=Frontiers in Cell and Developmental Biology

VOLUME=10

YEAR=2022

URL=https://www.frontiersin.org/journals/cell-and-developmental-biology/articles/10.3389/fcell.2022.909212

DOI=10.3389/fcell.2022.909212

ISSN=2296-634X

ABSTRACT=<p>Differential processing is a hallmark of clustered microRNAs (miRNAs) and the role of position and order of miRNAs in a cluster together with the contribution of stem-base and terminal loops has not been explored extensively within the context of a polycistronic transcript. To elucidate the structural attributes of a polycistronic transcript that contribute towards the differences in efficiencies of processing of the co-transcribed miRNAs, we constructed a series of chimeric variants of <italic>Drosophila let-7-Complex</italic> that encodes three evolutionary conserved and differentially expressed miRNAs (<italic>miR-100</italic>, <italic>let-7</italic> and <italic>miR-125</italic>) and examined the expression and biological activity of the encoded miRNAs. The kinetic effects of Drosha and Dicer processing on the chimeric precursors were examined by <italic>in vitro</italic> processing assays. Our results highlight the importance of stem-base and terminal loop sequences in differential expression of polycistronic miRNAs and provide evidence that processing of a particular miRNA in a polycistronic transcript is in part determined by the kinetics of processing of adjacent miRNAs in the same cluster. Overall, this analysis provides specific guidelines for achieving differential expression of a particular miRNA in a cluster by structurally induced changes in primary miRNA (pri-miRNA) sequences.</p>