Graduation Date

11-2014

Document Type

Master's Thesis

Degree Name

Master of Science

Department or Program

Biological Sciences

Department or Program Chair

Maggie Louie, PhD

First Reader

Kiowa Bower, PhD

Second Reader

Mohammed El Majdoubi, PhD

Abstract

Huntington’s disease (HD) is a heritable neurodegenerative disorder that affects muscle coordination and diminishes cognitive abilities, by affecting the medium spiny neurons in the brain. In HD patients, neurons are damaged and destroyed because of the toxicity of the mutant Huntington protein (mHtt). The mechanism of how mHtt protein affects the neurons is unknown. In this study we explored the effects of mHtt expression by looking at changes in huntingtin localization, changes in the expression and co-localization of related proteins and differences in cell morphology. We examine how this expression affects the cytoskeletal structures using neural stem cells Q7 (wild type) and Q140 (mHtt) and differentiated neurons as a model for studying HD. In addition we looked at the interference of mHtt protein with RRAS, the downstream signaling components of Plexin/Semaphorin pathway of the neurons. Our work began with optimization of the growth conditions of the cell lines of our model cell system. We then focused on developing protocols for differentiation into neurons, and continued with immunocytochemistry studies and confocal microscopy for imaging the fluorescently labeled cells. We found differences in growth rate and morphology between Q7 and Q140 cell lines. We studied the effects of mHtt protein on the differentiation process of the neurons and noticed differences in the mHtt protein expression between both differentiated cell lines. There is evidence that mHtt interferes with cell adhesion, motility, and molecules related to signaling and cytoskeleton remodeling. The results of these studies leave us with a well-characterized tool for the study of HD.

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