Dysregulation of RNA metabolism in FUS mutant human motor neurons: implications for Amyotrophic Lateral Sclerosis (ALS) Riccardo De Santis1,2, Vincenzo Alfano2, Alessio Colantoni2, Valeria de Turris1, Laura Santini2, Maria Giovanna Garone1,2, Giovanna Peruzzi1, Emanuel Wyler3, Markus Landthaler3, Irene Bozzoni2, Alessandro Rosa1,2,* 1Center for Life Nano Science, Istituto Italiano di Tecnologia, Rome, Italy; 2Department of Biology and Biotechnology Charles Darwin, Sapienza University of Rome, Rome, Italy; 3Max Delbrück Center for Molecular Medicine, Berlin, Germany *Corresponding Author
The motor neuron disease Amyotrophic Lateral Sclerosis (ALS) has been genetically linked to mutations in several RNA binding proteins (RBPs), including FUS, which is associated to severe and juvenile ALS. Increasing evidence points to the gain of toxic functions of mutant FUS as the major pathological mechanism, however the pathways leading to neurodegeneration remain largely unknown. To define the aberrant activities acquired by mutant FUS in the human motor neuron (hMN), we have generated human iPSCs carrying ALS FUS mutations introduced by gene editing and isogenic FUS wild type controls (Lenzi et al., 2015). We recently described alterations in the transcriptome and microRNA pathways in mutant iPSCs-derived hMNs (De Santis et al., 2017). Notably, mutant FUS is aberrantly localized in the cytoplasm and may alter cellular functions without affecting RNA levels, for instance by mislocalizing bound transcripts and/or dysregulating their translation. We defined the repertoire of RNA molecules bound by mutant FUS in hMNs by PAR-CLIP analysis. We found that the ALS mutation causes a major shift in FUS partners. Interestingly, transcripts encoding for RBPs are significantly enriched among mutant FUS interactors. We show that FUS binding to target 3'UTR resulted in increased protein levels. Interestingly, RBPs targeted by FUS have been found aberrantly upregulated and localized in pathological inclusions in both sporadic and familial ALS patients. Thus the relevance of our findings might be of broader interest to define the pathological mechanisms underlying ALS.
References: - Lenzi et al. (2015). Disease Models and Mechanisms 8: 755-766 - De Santis et al. (2017). Stem Cell Reports 9: 1450-1462
Funding: AriSLA pilot grant 2016 ''StressFUS''
Credits: None available.
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