RT Journal Article SR Electronic T1 Exploiting variability of single cells to uncover the in vivo hierarchy of miRNA targets JF bioRxiv FD Cold Spring Harbor Laboratory SP 035097 DO 10.1101/035097 A1 Andrzej J. Rzepiela A1 Arnau Vina-Vilaseca A1 Jeremie Breda A1 Souvik Ghosh A1 Afzal P. Syed A1 Andreas J. Gruber A1 William A. Grandy A1 Katja Eschbach A1 Christian Beisel A1 Erik van Nimwegen A1 Mihaela Zavolan YR 2015 UL http://biorxiv.org/content/early/2015/12/23/035097.abstract AB MiRNAs are post-transcriptional repressors of gene expression that may additionally reduce the cell-to-cell variability in protein expression, induce correlations between target expression levels and provide a layer through which targets can influence each other’s expression as ‘competing RNAs’ (ceRNAs). Here we combined single cell sequencing of human embryonic kidney cells in which the expression of two distinct miRNAs was induced over a wide range, with mathematical modeling, to estimate Michaelis-Menten (KM)-type constants for hundreds of evolutionarily conserved miRNA targets. These parameters, which we inferred here for the first time in the context of the entire network of endogenous miRNA targets, vary over ~2 orders of magnitude. They reveal an in vivo hierarchy of miRNA targets, defined by the concentration of miRNA-Argonaute complexes at which the targets are most sensitively down-regulated. The data further reveals miRNA-induced correlations in target expression at the single cell level, as well as the response of target noise to the miRNA concentration. The approach is generalizable to other miRNAs and post-transcriptional regulators and provides a deeper understanding of gene expression dynamics.