Year

2020

Season

Spring

Paper Type

Master's Thesis

College

College of Arts and Sciences

Degree Name

Master of Science in Biology (MS)

Department

Biology

NACO controlled Corporate Body

University of North Florida. Department of Biology

First Advisor

Dr. David Waddell, Ph.D.

Second Advisor

Dr. Frank Smith, Ph.D.

Third Advisor

Dr. Michael Lentz, Ph.D.

Abstract

Skeletal muscle atrophy is a debilitating condition that can arise due to aging, cancer, corticosteroid use, and denervation. To better characterize the molecular genetic events of neurogenic atrophy, a previous study analyzed gene expression patterns in gastrocnemius muscle following sciatic nerve transection and found for the first time that Zinc Finger Protein 593 (Zfp593) and 1700029J07RIK are expressed in skeletal muscle and are induced in response to denervation. Quantitative PCR confirmed that Zfp593 and 1700029J07RIK are expressed in both proliferating myoblasts and differentiated myotubes. To assess sub-cellular location, GFP-tagged Zfp593 and 1700029J07RIK were expressed in C2C12 cells. Zfp593 was found to localize to the nucleus, while 1700029J07RIK was localized to the nuclear envelope and cytoskeleton of proliferating myoblasts, but to the nucleus of differentiated myotubes. The Zfp593 protein possesses a putative zinc finger domain and is believed to function as a modulator of the Oct-1 transcription factor. However, ectopic expression of Zfp593 did not affect the ability of Oct-1 or Oct-2 to inhibit an Oct reporter gene in muscle cells. Zfp593 overexpression in cultured muscle cells resulted in significant repression of muscle cell differentiation and attenuation of ERK1/2 and p38 phosphorylation but did not vitiate protein synthesis. 1700029J07RIK overexpression also resulted in inhibition of muscle cell differentiation and a significant reduction in ERK1/2 phosphorylation. Additionally, 1700029J07RIK overexpression attenuated AKT phosphorylation and inhibited Gli2 protein levels, along with cytoskeleton proteins desmin, vimentin, and tubulin. Interestingly, we found that 1700029J07RIK overexpression stabilized Nesprin-1 protein during muscle cell differentiation. The discovery that Zfp593 and 1700029J07RIK are expressed in skeletal muscle combined with the observation that they are induced in response to neurogenic atrophy furthers our understanding of the molecular genetic events of muscle wasting.

Available for download on Saturday, May 03, 2025

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