Nucleation and dissolution mechanism underlying amyotrophic lateral sclerosis/frontotemporal lobar dementia-linked fused in sarcoma condensates

Nathalie A Djaja; Matthew T Chang; Freya R Beinart; Vivian M Morris; Laura R Ganser; Sua Myong

doi:10.1016/j.isci.2023.106537

Nucleation and dissolution mechanism underlying amyotrophic lateral sclerosis/frontotemporal lobar dementia-linked fused in sarcoma condensates

iScience. 2023 Mar 31;26(4):106537. doi: 10.1016/j.isci.2023.106537. eCollection 2023 Apr 21.

Authors

Nathalie A Djaja¹, Matthew T Chang², Freya R Beinart³, Vivian M Morris⁴, Laura R Ganser², Sua Myong^{1

5}

Affiliations

¹ Program in Cellular Molecular Developmental Biology and Biophysics, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA.
² Department of Biophysics, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA.
³ Department of Biology, Kenyon College, 106 College Park Dr, Gambler, OH 43022, USA.
⁴ Lymphoid Malignancy Branch, National Cancer Institute, National Institutes of Health, Building 10, Bethesda, MD 20814, USA.
⁵ T.C. Jenkins Department of Biophysics, Johns Hopkins University, 3400 N. Charles Street, Baltimore, MD 21218, USA.

Abstract

Fused in sarcoma (FUS) is a nuclear RNA-binding protein. Mutations in FUS lead to the mislocalization of FUS from the nucleus to the cytosol and formation of pathogenic aggregates in neurodegenerative diseases including amyotrophic lateral sclerosis (ALS) and frontotemporal lobar dementia (FTLD), yet with unknown molecular mechanisms. Using mutant and stress conditions, we visualized FUS localization and aggregate formation in cells. We used single-molecule pull-down (SiMPull) to quantify the native oligomerization states of wildtype (WT) and mutant FUS in cells. We demonstrate that the NLS mutants exhibited the highest oligomerization (>3) followed by other FUS mutants (>2) and WT FUS which is primarily monomeric. Strikingly, the mutant FUS oligomers are extremely stable and resistant to treatment by high salt, hexanediol, RNase, and Karyopherin-β2 and only soluble in GdnHCl and SDS. We propose that the increased oligomerization units of mutant FUS and their high stability may contribute to ALS/FTLD pathogenesis.

Keywords: Biophysics; Molecular interaction; Properties of biomolecules.

Abstract

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