Pillman, K.A.Goodall, G.J.Bracken, C.P.Gantier, M.P.2019-03-252019-03-252019RNA: A publication of the RNA Society, 2019; 25(2):232-2381355-83821469-9001http://hdl.handle.net/2440/118353Most microRNAs (miRNAs) are expressed as a mix of length isoforms (referred to as isomiRs). IsomiR stoichiometry can be differentially impacted upon cell stimulation, as recently evidenced by our group in the context of immune responses induced by type-I interferon (IFN). Here, we revisit published RNA-seq data sets of human and mouse macrophages stimulated with bacterial products at the isomiR level. We demonstrate that for several miRNAs, macrophage stimulation induces changes in isomiR stoichiometry. Critically, we find that changes in miRNA expression can be misinterpreted when miRNAs are quantified by RT-qPCR, as primers directed against canonical miRNA sequences may not equally target the different isomiRs that are regulated endogenously. Beyond the case of phagocyte stimulation, our analyses reinforce the concept that analysis of miRNA expression at the isoform level should become standard practice.en© 2019 Pillman et al.; Published by Cold Spring Harbor Laboratory Press for the RNA Society. This article is distributed exclusively by the RNA Society for the first 12 months after the full-issue publication date (see http://rnajournal.cshlp.org/site/misc/terms.xhtml). After 12 months, it is available under a Creative Commons License (Attribution-NonCommercial 4.0 International), as described at http://creativecommons.org/licenses/by-nc/4.0/.MicroRNA isoform; isomiR; interferon; LPS; RT-qPCR miRNA assays; macrophages; bacterial infectionJournal article003010833110.1261/rna.069047.1180004558557000062-s2.0-85060142184451767Pillman, K.A. [0000-0002-5869-889X]Goodall, G.J. [0000-0003-1294-0692]