Modeling neurodevelopmental disorder-associatedhAGO1mutations inC. elegansArgonauteALG-1

Abstract

ABSTRACTMicroRNAs (miRNA) are endogenous non-coding RNAs important for post-transcriptional regulation of gene expression. miRNAs associate with Argonaute proteins to bind to the 3’ UTR of target genes and confer target repression. Recently, multiplede novocoding variants in the human Argonaute geneAGO1(hAGO1) have been reported to cause a neurodevelopmental disorder (NDD) with intellectual disability (ID). Most of the altered amino acids are conserved between the miRNA-associated Argonautes inH. sapiensandC. elegans, suggesting thehAGO1mutations could disrupt evolutionarily conserved functions in the miRNA pathway. To investigate how thehAGO1mutations may affect miRNA biogenesis and/or functions, we genetically modeled four of thehAGO1 de novovariants (referred to as NDD mutations) by introducing the identical mutations to theC. elegans hAGO1 homolog, alg-1. This array of mutations caused distinct effects onC. elegansmiRNA functions, miRNA populations, and downstream gene expression, indicative of profound alterations in aspects of miRNA processing and miRISC formation and/or activity. Specifically, we found that thealg-1NDD mutations cause allele-specific disruptions in mature miRNA profiles both in terms of overall abundances and association with mutant ALG-1. We also observed allele-specific profiles of gene expression with altered translational efficiency and/or mRNA abundance. The sets of perturbed genes include human homologs whose dysfunction is known to cause NDD. We anticipate that these cross-clade genetic studies may advance the understanding of fundamental Argonaute functions and provide insights into the conservation of miRNA-mediated post-transcriptional regulatory mechanisms.