|Edward P. Debold
Assistant Professor of Kinesiology, University of Massachusetts
Ph.D.: Marquette University
Muscle Myosin in Cardiovascular Disease and Muscular Fatigue
Muscle generates the force and motion required to power a wide range of important tasks, from walking to the pumping of blood by the heart. The ability to accomplish these tasks is ultimately derived from the nano-scale motions of muscle's motor enzyme, myosin. At the molecular level, myosin generates force and motion through the rotation of a long alpha helical region of myosin (a.k.a. lever-arm) while it is strongly bound to its molecular partner, actin, in a process ultimately powered by ATP hydrolysis. Advances in single molecule biophysical techniques have provided researchers with the ability to directly observe these nanometer scale motions of myosin, offering unprecedented insight into the molecular function of muscle. These advances are also helping to reveal the root molecular causes of muscle dysfunction, such as heart failure and muscular fatigue.
In the Muscle Biophysics Laboratory we use fluorescence microscopy and single molecule laser-trap techniques to gain unique insight into the molecular events that underlie basic muscle function in health and disease. In one approach, we take advantage of point mutations in contractile proteins, for example those associated with genetic cardiomyopathies, to determine the relationship between the structure and function of several muscle contractile proteins. The functional properties are quantified using the in vitro motility assay, and unitary measures of myosin's displacement and actin binding lifetime using a "three-bead" single molecule laser-trap assay. In a related approach we determine the molecular mechanics and kinetics of myosin under conditions that simulate extreme stress such as during a heart attack or severe muscular fatigue. We hope these lines of investigation will both improve our basic understanding of muscle function and reveal the root molecular causes of related diseases, ultimately leading to improved treatments.
Debold EP. Recent insights into muscle fatigue at the cross-bridge level..Front Physiol. 2012;3:151. Epub 2012 Jun 1.
Debold, E.P., S.E. Beck and David Warshaw. Effect of low pH on single skeletal muscle myosin mechanics and kinetics. American Journal of Physiology (Cell. Physiol.)295:C173-179, 2008.
Schmitt Joachim P., Debold, E.P.(co-first author), Ferhaan Ahmad, Amy Armstrong, Andrea Frederico, David A. Conner, Ulrike Mende, Martin J. Lohse, David Warshaw, Christine E. Seidman, and J. G. Seidman. Cardiac myosin missense mutations cause dilated cardiomyopathy in mouse models and depress molecular motor function. Proceedings of the National Academy of Science 103:14525-14530, 2006.
Debold, E.P., Amy Armstrong, Andrea Frederico, J.G. Seidman, David Warshaw. Hypertrophic and dilated cardiomyopathy myosin mutations studied using a novel load-clamped laser trap assay. American Journal of Physiololgy (Heart Circ. Physiol.) 293:H284-291, 2007.
Debold, E.P., Romatowski, J., and R. Fitts. The depressive effect of Pi on the force-calcium relationship in skinned single muscle fibers is temperature dependent. American Journal of Physiology (Cell Physiol.) 290:C1041-50, 2006.
Debold, E.P., J. B. Patlak, D. M. Warshaw. Slip sliding away: load dependence of velocity generated by skeletal muscle myosin molecules in the laser trap. Biophysical Journal 89: L34-6, 2005.
Debold, E.P., Dave, H. and Fitts, R.H. Fiber type and temperature dependence of inorganic phosphate: implications for fatigue. American Journal of Physiology (Cell Physiol.): 287:C673-C681, 2004.