Graduation Date

Summer 8-9-2024

Document Type

Thesis

Degree Name

Master of Science (MS)

Programs

Biochemistry & Molecular Biology

First Advisor

Paul Sorgen, Ph.D.

Abstract

Proper contraction of the heart relies on gap junction channels (GJCs) composed of Cx40 and Cx43 in the atrial and ventricular tissues which mediate electrical conductance in the working myocardium. Also expressed is Cx45, which is limited to the pacemaker system. Studies in diseased human hypertrophic cardiac tissue have shown expression of Cx45 and decrease of Cx43 in the myocardium. Cx43 and Cx45 in vitro form heterometric GJCs, where the channel characteristics (metabolite transfer, electrical conductance, etc.) resemble those of Cx45. There is little-to-no data showing whether GJCs composed of Cx43 and Cx45 in cardiac hypertrophy result in altered conductance. We hypothesize that an increase in Cx45 will result in conductance different from healthy cardiomyocytes, and that this altered conductance increases susceptibility to arrythmias and heart failure. Using GM25256 hiPSCs, GSK-3 and Wnt signaling were modulated to create cardiomyocytes. These cells were transduced with AAV6 vectors encoding Cx43, Cx45, or both. Expression of Cx43 and Cx45 were evaluated by Western blot and immunofluorescence. Our data shows differentiation of the hiPSCs through increased Troponin-T expression. We are currently evaluating the expression and conductance of Cx43 and Cx45 via microelectroarray conductance measurements. This study aims to establish whether heteromeric Cx43/Cx45 channels in cardiac tissue result in increased arrhythmias. If true, Cx45 could be a novel target for clinical therapeutics to restore cardiac function in advanced cardiac disease.

Comments

2024 Copyright, the authors

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