A genome-wide Drosophila RNAi screen identifies DYRK-family kinases as regulators of NFAT

Down's syndrome is caused by an extra chromosome; somehow a 1.5-fold increase in the dosage of a gene or genes on chromosome 21 causes the wide-reaching effects associated with the condition. A study using ‘knockout’ mice now identifies two genes as candidates for involvement. A 1.5-fold increase in dosage of DSCR1 and DYRK1a destabilizes the regulation of signalling pathways involving the NFAT transcription factor. The discovery follows the surprise finding that NFATc1-4 and calcineurin mutant mice demonstrate nearly all the characteristics of Down's syndrome. In an unrelated paper, a genome-wide RNAi screen reveals conserved regulators of NFAT in Drosophila. NFAT is a purely vertebrate transcription factor, but this work breaks new ground by using Drosophila cells to study the function of a protein artificially introduced from a mammalian species. Pathways regulating the subcellular localization of NFAT proteins are strongly conserved across species and this new approach can identify new regulators of a transcription factor normally expressed in vertebrates.