Divergent FUS phosphorylation in primate and mouse cells following double-strand DNA damage

• Type of Material: Article
• Authors: Michelle A. Johnson, Emory University; Qiudong Deng, Emory University; Georgia Taylor, Emory University; Zachary McEachin, Emory University; Anthony Chan, Emory University; Jessica Root, Emory University; Gary Bassell, Emory University; Thomas Kukar, Emory University
• Language: English
• Date: 2021-04-23
• Publisher: Elsevier
• Publication Version: Author Accepted Manuscript (After Peer Review)
• Copyright Statement: © 2020 The Authors. Published by Elsevier Inc.
• License: Creative Commons Attribution-NonCommercial-NoDerivs 4.0 International
• Final Published Version (URL): http://dx.doi.org/10.1016/j.nbd.2020.105085
• Title of Journal or Parent Work: NEUROBIOLOGY OF DISEASE
• Volume: 146
• Grant/Funding Information: This work was supported by the National Institutes of Health (NIH)/NINDS grants (R01 NS093362, R01 NS105971), a New Vision Research Investigator Award, an Emory Alzheimer’s Disease Center Pilot Grant P50AG025688, the Alzheimer’s Drug Discovery Foundation and the Association for Frontotemporal Degeneration (ADDF/AFTD), the Bluefield Project to Cure Frontotemporal Dementia, and the BrightFocus Foundation to Thomas Kukar.
• Keywords: DNA damage; DNA-dependent protein kinase (DNA-PK); Frontotemporal dementia (FTD); Phosphorylation; Amyotrophic lateral sclerosis (ALS); Fused in sarcoma (FUS); Species specific response; Calicheamicin γ1 (CLM)

Abstract

Fused in sarcoma (FUS) is a RNA/DNA protein involved in multiple nuclear and cytoplasmic functions including transcription, splicing, mRNA trafficking, and stress granule formation. To accomplish these many functions, FUS must shuttle between cellular compartments in a highly regulated manner. When shuttling is disrupted, FUS abnormally accumulates into cytoplasmic inclusions that can be toxic. Disrupted shuttling of FUS into the nucleus is a hallmark of ~10% of frontotemporal lobar degeneration (FTLD) cases, the neuropathology that underlies frontotemporal dementia (FTD). Multiple pathways are known to disrupt nuclear/cytoplasmic shuttling of FUS. In earlier work, we discovered that double-strand DNA breaks (DSBs) trigger DNA-dependent protein kinase (DNA-PK) to phosphorylate FUS (p-FUS) at N-terminal residues leading to the cytoplasmic accumulation of FUS. Therefore, DNA damage may contribute to the development of FTLD pathology with FUS inclusions. In the present study, we examined how DSBs effect FUS phosphorylation in various primate and mouse cellular models. All cell lines derived from human and non-human primates exhibit N-terminal FUS phosphorylation following calicheamicin γ1 (CLM) induced DSBs. In contrast, we were unable to detect FUS phosphorylation in mouse-derived primary neurons or immortalized cell lines regardless of CLM treatment, duration, or concentration. Despite DNA damage induced by CLM treatment, we find that mouse cells do not phosphorylate FUS, likely due to reduced levels and activity of DNA-PK compared to human cells. Taken together, our work reveals that mouse-derived cellular models regulate FUS in an anomalous manner compared to primate cells. This raises the possibility that mouse models may not fully recapitulate the pathogenic cascades that lead to FTLD with FUS pathology.