# Nucleation and Dissolution Mechanism Underlying ALS/FTLD-linked FUS Condensates > **NIH NIH F31** · JOHNS HOPKINS UNIVERSITY · 2022 · $46,752 ## Abstract PROJECT SUMMARY Fused in sarcoma (FUS) is an RNA binding protein which can readily undergo liquid-liquid phase separation (LLPS) to perform its proper functions in the nucleus. Mutations in FUS and/or cellular stress lead to mislocalization of FUS from the nucleus to the cytosol and aberrant LLPS, leading to the formation of toxic aggregates that are more gel-like or solid-like than wild type (WT) FUS whose condensates have dynamic liquid- like properties. Toxic aggregates of mutant FUS is a hallmark of age-dependent neurodegenerative diseases such as amyotrophic lateral sclerosis (ALS) and frontotemporal lobar dementia (FTLD) which are characterized by a progressive loss of motor neurons and eventual death in patients. I propose to identify mechanisms underlying the formation of cytotoxic FUS aggregates which contribute to the death of motor neurons and disease progression. Specifically, I propose to utilize single molecule techniques to investigate the nucleation and dissolution mechanisms underlying FUS aggregation and the underlying interactions driving FUS LLPS which become perturbed in disease-linked mutants. Aim 1 will quantify the oligomerization status of FUS in cells under WT, stressed and mutant conditions using single molecule pulldown (SiMPull) analysis. This aim will test the impact of multiple ALS/FTLD-linked FUS mutations multiple forms of stress on FUS oligomerization in a localization-dependent manner. Aim 2 will utilize in vitro nucleation and dissolution assays to compare the nucleation pattern of WT versus mutant FUS oligomers and will identify the mechanism of action underlying FUS condensate assembly. In addition, aim 2 will test the interactions necessary to maintain FUS condensates using dissolution assays with a panel of various dissolving agents that will perturb hydrophobic, electrostatic, and RNA interactions, to investigate the effects of loss of respective interactions on FUS oligomers. Aim 3 will investigate the role of FUS-RNA interactions in FUS nucleation by determining the RNA sequences, lengths, and structures necessary for nucleating and maintaining FUS condensates, and will identify interactions that are disrupted in ALS/FTLD-linked mutant FUS condensates. This proposal is strengthened by contributions from three collaborators (see support letters), all of whom are experts on ALS, LLPS, or can provide technical support. The activities planned under this award including collaborations, professional development opportunities, engaging and participating in scientific conferences, mentoring undergraduates in the lab, and improving scientific communication and critical thinking skills will allow me to successfully complete my PhD and prepare me for a postdoctoral position and later, to attain a career in academia. This proposal will allow me to pursue my long- term career goal and will utilize single molecule techniques to gain a better mechanistic understanding of ALS/FTLD-linked FUS mutants to prevent disease p... ## Key facts - **NIH application ID:** 10474309 - **Project number:** 5F31NS124267-02 - **Recipient organization:** JOHNS HOPKINS UNIVERSITY - **Principal Investigator:** Nathalie Ashley Djaja - **Activity code:** F31 (R01, R21, SBIR, etc.) - **Funding institute:** NIH - **Fiscal year:** 2022 - **Award amount:** $46,752 - **Award type:** 5 - **Project period:** 2021-08-01 → 2024-07-31 ## Primary source NIH RePORTER: https://reporter.nih.gov/project-details/10474309 ## Citation > US National Institutes of Health, RePORTER application 10474309, Nucleation and Dissolution Mechanism Underlying ALS/FTLD-linked FUS Condensates (5F31NS124267-02). Retrieved via AI Analytics 2026-05-23 from https://api.ai-analytics.org/grant/nih/10474309. Licensed CC0. --- *[NIH grants dataset](/datasets/nih-grants) · CC0 1.0*