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Investigating the Role of Nuclear Pore Complex and Nucleocytoplasmic Transport Alterations in Multiple Sclerosis and Related Neurodegenerative Diseases

Date

2024-05-01

Journal Title

Journal ISSN

Volume Title

Publisher

ORCID

0000-0003-3780-139X

Type

Thesis

Degree Level

Masters

Abstract

Multiple sclerosis (MS), classically known as an autoimmune, demyelinating disease of the central nervous system, has a significant neurodegenerative component which underlies permanent disability in MS patients. Current MS treatments are immunomodulatory and can decrease relapses, but no treatments target neurodegeneration, which drives disease progression. Dysfunctional RNA binding proteins (RBPs) are a common mechanism of many neurodegenerative diseases, including MS. The nuclear pore complex (NPC) and nucleocytoplasmic transport are critical to the proper functioning of cells, but are altered in neurodegenerative diseases, including Huntington’s disease, amyotrophic lateral sclerosis, and Alzheimer’s disease. Previous RNA sequencing data from our lab identified differentially expressed genes related to the NPC and nucleocytoplasmic transport in cells with knockdown of an RBP. The function of the NPC and nucleocytoplasmic transport has yet to be studied in MS. I hypothesized that the NPC is perturbed in MS and a related model of RBP dysfunction, affecting normal nucleocytoplasmic transport, potentially contributing to neurodegeneration. Knockdown of the RBP heterogeneous nuclear ribonucleoprotein A1 (hnRNP A1) in Neuro2a cells (a neuronal-like cell line), a model of RBP dysfunction, significantly affected the structure of the nuclear envelope. Next, I generated a novel method to classify Lamin B staining patterns of the nuclear envelope to improve analyses and reduce bias. Using this method, I replicated the finding that hnRNP A1 loss alters the nuclear envelope. The structure of the NPC itself was significantly affected and the expression of two NPC proteins was decreased. Then, using a previous RNA sequencing dataset of hnRNP A1 knockdown, I performed gene ontology analysis and found alterations in pathways related to the NPC and nucleocytoplasmic transport, providing support to the role of the NPC and nucleocytoplasmic transport play in the pathogenesis of MS. The nuclear envelope remained intact, but active nucleocytoplasmic transport was perturbed, leading to mislocalization of a protein undergoing continuous transport through the NPC. I then validated my findings in human tissues and determined that Lamin B staining was significantly altered in MS compared to controls. These results demonstrate that dysfunctional RBPs can affect the nuclear envelope and the NPC. Perturbations in nucleocytoplasmic transport can lead to further protein mislocalization, exacerbating RBP dysfunction and nuclear RNA accumulation thereby affecting protein synthesis. Dysfunctional nucleocytoplasmic transport, which can lead to neuronal cell death, is a novel mechanism implicated in the pathogenesis of MS.

Description

Keywords

Nuclear pore complex, Nucleocytoplasmic transport

Citation

Degree

Master of Science (M.Sc.)

Department

Anatomy, Physiology, and Pharmacology

Program

Anatomy, Physiology, and Pharmacology

Part Of

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DOI

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