A Haploid Genetic Screening Method for Proteins Influencing Mammalian Nonsense-Mediated mRNA Decay Activity

Despite a long appreciation for the role of nonsense-mediated mRNA decay (NMD) in the destruction of faulty, disease-causing mRNAs, as well as its role in the maintenance of normal, endogenous transcript abundance, systematic unbiased methods for uncovering modifiers of NMD activity in mammalian cells remain scant. Here we present and validate a haploid genetic screening method for identifying proteins and processes that stimulate NMD activity involving a 3′-untranslated region exon-junction complex. This reporterbased screening method can be adapted for interrogating other pathways whose output can be measured by the intracellular production of fluorescent proteins.