Familial hypertrophic cardiomyopathy (FHC) is the leading cause of sudden cardiac death in both preadolescents and adolescents. The hallmark of the disorder is myocardial hypertrophy of the left ventricle, which results in an obstruction of blood flow through the left ventricular outflow tract. FHC has been associated with well over 100 mutations, primarily in proteins of the contractile apparatus of the heart. The molecular mechanisms involved in the pathogenesis of FHC are not well understood. For this study, in vitro motility assays (IVM) were conducted to assess the relationship between structure and function of cardiac thin filaments and to elucidate the molecular basis for sequelae of FHC caused by point mutations in the human cardiac regulatory proteins. Our research aims to contribute to the study of FHC by the accomplishment of the following innovations: 1) Development of a simple strategy to express recombinant human cardiac regulatory proteins in E. coli for molecular assays of human cardiac contractility. 2) Fabrication of a thermo-electric controller that allows rapid and reversible characterization over a broad temperature range of the effects of FHC mutations in troponin and tropomyosin using IVM assays. My research yielded the following novel physiological findings 1) Ca2+-sensitivity of human cardiac thin filament sliding is affected by some of the FHC mutations in the cardiac regulatory proteins, but not by changes in myosin isoform, indicating that Ca2+-sensitivity does not depend upon the kinetics of cross-bridge cycling. This finding implies that the hypertrophic response is communicated through different pathways depending whether the mutation is in troponin, tropomyosin, or myosin 2) Troponin and tropomyosin affect the temperature sensitivity as well as the maximum speed of unloaded filament sliding by reducing the myosin cross-bridge duty ratio. Our results suggest that the duty ratio also might be affected by clinically relevant mutations in troponin and tropomyosin. Finally, functional characterization of troponin, bearing FHC mutations in subunit I, subunit T, or both subunits, predicts structural relationships of the thin filament. / A Dissertation submitted to the Program in Molecular Biophysics in partial fulfillment of the requirements for the degree of Doctor of Philosophy. / Fall Semester, 2006. / October 25, 2006. / Troponin, Calciun Sensitivity, Temperature, Familial Hypertrophic Cardiomyopathy, Thermal Stability, Cross-Bridge Cycle, Tropomyosin / Includes bibliographical references. / P. Bryant Chase, Professor Directing Dissertation; Peng Xiong, Outside Committee Member; Timothy S. Moerland, Committee Member; Peter G. Fajer, Committee Member; Thomas C. S. Keller, III, Committee Member.
| Identifer | oai:union.ndltd.org:fsu.edu/oai:fsu.digital.flvc.org:fsu_181124 |
| Contributors | Brunet, Nicolas (authoraut), Chase, P. Bryant (professor directing dissertation), Xiong, Peng (outside committee member), Moerland, Timothy S. (committee member), Fajer, Peter G. (committee member), Keller, Thomas C. S. (committee member), Program in Molecular Biophysics (degree granting department), Florida State University (degree granting institution) |
| Publisher | Florida State University, Florida State University |
| Source Sets | Florida State University |
| Language | English, English |
| Detected Language | English |
| Type | Text, text |
| Format | 1 online resource, computer, application/pdf |
| Rights | This Item is protected by copyright and/or related rights. You are free to use this Item in any way that is permitted by the copyright and related rights legislation that applies to your use. For other uses you need to obtain permission from the rights-holder(s). The copyright in theses and dissertations completed at Florida State University is held by the students who author them. |
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