show Abstracthide AbstractHuntington's disease (HD) is an inherited and incurable neurodegenerative disorder caused by CAG repeat expansions in the huntingtin (HTT) gene. The resulting mutant HTT protein alters cellular physiology at multiple levels, inducing toxicity and cell death. The mechanisms directly causing toxicity are partially understood, thus precluding the development of effective therapeutic strategies. Here we identified novel suppressors of mutant HTT toxicity by performing a genome-wide screen in pluripotent stem cells, followed by hit validation both in zebrafish and mouse HD models. The candidate suppressors identified were strongly enriched for HD-associated processes. We focused on Metal regulatory transcription factor 1 (Mtf1), a transcription factor controlling metal homeostasis in the cell. Forced expression of Mtf1 counteracts cell death, oxidative stress and transcriptional alterations caused by mutant HTT in pluripotent cells. In zebrafish, Mtf1 reduces malformations and apoptosis induced by mutant HTT, while Mtf1 delivery by Adeno-Associated viral (AAV) vectors ablated motor defects observed in an HD mouse model. Our data reveal that delivery of Mtf1 might act as a novel therapeutic strategy against HD and potentially other neurodegenerative disorders. Overall design: Library Preparation Total RNA was quantified using the Qubit 2.0 fluorimetric Assay (Thermo Fisher Scientific). Libraries were prepared from (125* - 250** - 250***) ng of total RNA using a 3'DGE mRNA-seq (research*/clinical**/diagnostic***) grade sequencing service (Next Generation Diagnostics srl)1 which included library preparation, quality assessment and sequencing on a NovaSeq 6000 sequencing system using a single-end, 100 cycle strategy (Illumina Inc.). Bioinformatics workflow The raw data were analyzed by Next Generation Diagnostics srl proprietary 3'DGE mRNA-seq pipeline (v2.0) which involves a cleaning step by quality filtering and trimming, alignment to the reference genome and counting by gene. We have filtered out all genes having < 1 cpm in less than n_min samples and Perc MM reads > 20% simultaneously. Differential expression analysis was performed using edgeR.