GSBS Dissertations and Theses

Approval Date

8-14-2015

Document Type

Master's Thesis

Academic Program

Biochemistry and Molecular Pharmacology

Department

Neurology

First Thesis Advisor

Daryl A. Bosco, PhD

Keywords

stress granules, Mutant FUS, Fused in Sarcoma/Translocated in Liposarcoma, Amyotrophic Lateral Sclerosis, ALS

Subjects

Theses, UMMS; Amyotrophic Lateral Sclerosis; Stress, Physiological; Cytoplasmic Granules; Oxidative Stress; RNA-Binding Protein FUS

Abstract

During stress, eukaryotes regulate protein synthesis in part through formation of cytoplasmic, non-membrane-bound complexes called stress granules (SGs). SGs transiently store signaling proteins and stalled translational complexes in response to stress stimuli (e.g. oxidative insult, DNA damage, temperature shifts and ER dysfunction). The functional outcome of SGs is proper translational regulation and signaling, allowing cells to overcome stress.

The fatal motor neuron disease Amyotrophic Lateral Sclerosis (ALS) develops in an age-related manner and is marked by progressive neuronal death, with cytoplasmic protein aggregation, excitotoxicity and increased oxidative stress as major hallmarks. Fused in Sarcoma/Translocated in Liposarcoma (FUS) is an RNA-binding protein mutated in ALS with roles in RNA and DNA processing. Most ALS-associated FUS mutations cause FUS to aberrantly localize in the cytoplasm due to a disruption in the nuclear localization sequence. Intriguingly, pathological inclusions in human FUSALS cases contain aggregated FUS as well as several SG-associated proteins. Further, cytoplasmic mutant FUS incorporates into SGs, which increases SG volume and number, delays SG assembly, accelerates SG disassembly, and alters SG dynamics.

I posit that mutant FUS association with stress granules is a toxic gain-of-function in ALS that alters the function of SGs by interaction with SG components. Here, I show that mutant FUS incorporates in to SGs via its Cterminal RGG motifs, the methylation of which is not required for this localization. Further, I identify protein interactions specific to full-length mutant FUS under stress conditions that are potentially capable of interacting with FUS in SGs. Finally, I demonstrate a potential change in the protein composition of SGs upon incorporation of mutant FUS. These findings advance the field of ALS and SG biology, thereby providing groundwork for future investigation.

DOI

10.13028/M2XK58

Rights and Permissions

Copyright is held by the author, with all rights reserved.

Available for download on Monday, August 27, 2018

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