Undergraduate Honors Theses

Thesis Defended

Spring 2019

Document Type

Thesis

Type of Thesis

Departmental Honors

Department

Molecular, Cellular, & Developmental Biology

First Advisor

Bradley Olwin

Abstract

Skeletal muscle is required for breathing and voluntary movement and loss of muscle mass is a significant contributor to humans’ inability to stay active throughout their entire lifespan. Skeletal muscle consists of multinucleated cells and there is no comprehensive data on the gene expression of the hundreds of nuclei located in a single myofiber required for contraction, attachment to tendons and force generation. Typical methodologies to examine gene expression of single cells cannot be performed on skeletal muscle because individual cells are large and multinucleated. Single nucleus sequencing can be exploited to examine differential gene expression that likely occurs among the hundreds of myonuclei organized within the myofiber. Isolation of nuclei from skeletal muscle previously done masked variability that exists in different muscles and types. I devised a protocol to isolate nuclei from a single muscle. I validated the method and performed it in multiple muscle groups, allowing the study of different expression profiles from a single mouse. The established protocol was employed in conjunction with single nucleus RNA Sequencing to investigate differential gene expression in the nuclei of adult, aged, and injured muscle. Preliminary analysis of adult muscle indicates clusters of myonuclei and mononucleated cells. There was widespread misregulation in aged muscle, myonuclei genes were expressed in all clusters and some of the mononucleated populations were undetected. Satellite cell nuclei present in uninjured aged muscle have become activated, impairing the longevity of muscle maintenance. This work could provide new therapeutic targets to prevent the age induced loss of muscle regeneration.

Available for download on Sunday, April 11, 2021

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