Dr. P. Bryant Chase
Ph.D., University of Southern California, 1984
Graduate Faculty Status
Research and Professional Interests:
Biomechanics of cardiac and skeletal muscle; BioNanotechnologyGeneral research areas: Biophysics of muscle tissue, molecular motor proteins, and calcium regulation of contraction; cellular and molecular biomechanics of cardiac and skeletal muscle; BioNanotechnology.
Research tools: Cellular and molecular biomechanical assays of permeabilized cardiac and skeletal muscle; in vitro motility assays; molecular biology; bioinformatics; biochemical and biomechanical modeling.
Major ongoing projects: Functional consequences of mutations in troponin I that cause hypertrophic cardiomyopathy; molecular and cellular biochemical/biomechanical model of striated muscle—a component of NASA/NSBRI’s "digital human." Inquire about additional projects.
The central theme of my research program is to understand the biophysical basis of biological motility, its regulation, and its modulation by cellular metabolism. Much remains to be learned about actomyosin interactions and their regulation, especially in cardiovascular function and diseases, cancer (metastasis), human performance, and bionanotechnology (biological nanomotors and protein mechanics). My experimental work has most often been directed toward answering molecular and cellular questions related to these topics; future experimental directions are, at one end of the spectrum, integrative studies using intact animals and, at the other, investigations at the single molecule level.
Troponin I and cardiac hypertrophy: In terms of clinical significance, the most important application—and currently my main focus—is understanding specific forms of cardiovascular disease, particularly the inherited (familial) forms of hypertrophic cardiomyopathy (FHC) and idiopathic dilated cardiomyopathy (IDC). In the first stage of the project, mutant forms of cardiac troponin I or troponin T are expressed in E. coli for incorporation into molecular and cellular assays that will test for changes in biomechanical function relative to wild type proteins. In its simplest terms, the hypothesis we are testing is whether the mutations cause hypertrophy by inhibiting function (causing compensatory hypertrophy) or by enhancing function (causing exercise-like hypertrophy). In later stages of the project, we will test whether mutants affect cardiac-specific modulations: sarcomere length (Starling’s law) and protein phosphorylation associated with adrenergic stimulation. See Chase et al. (2001) Biophys. J. 80:342a. These studies complement our previous work on troponin C, the calmodulin-like, Ca2+-binding subunit of troponin.
Metabolites, fatigue, and ischemia (intracellular environment): A long-standing problem I have worked on is the cellular basis for contractile deficit in fatigue or ischemia. We use permeabilized cellular preparations—in which we directly control metabolite concentrations (e.g., of ATP, ADP, Pi, [H+], and others)—to study the effects of altered metabolite levels on contractility. Related investigations use structural analogs of inorganic phosphate, aluminum fluoride, and beryllium fluoride. These analogs are interesting for biomechanical studies not only because they permit investigation of Pi in force generation but also for evaluation the physiological relevance of crystallographic structures of myosin motor domain complexes containing these analogs—structures considered central to our understanding of how molecular motors work. Other recent studies involve deoxy-ATP as a substrate for actomyosin. The biomechanical response to changes in metabolite concentration depends on the protein isoform(s) being studied (different proteins from different genes or from alternative splicing of mRNA) and could be altered by FHC-related mutations in cTnI (see above).
Modeling: A third research area is molecular and cellular biochemical and biomechanical modeling. Our Monte-Carlo modeling suggests that biomechanical "tuning" arises from finite stiffness of the proteins, and that this property contributes to apparent cooperativity of force generation in the steady-state, isometric situation. This tuning, observed under load-bearing conditions, will probably be an important design consideration for nanomechanical systems. Future directions for this project include expanding the model to handle larger ensembles of molecules and developing the tools necessary to test the model predictions.
Front row: Katie Tieman, Dr. Chase, Maggie Shoemaker, Myriam Badr.
Schoffstall, B., N. M. Brunet, F. Wang, S. Williams, A. T. Barnes, V. F. Miller, L. A. Compton, L. A. McFadden, D. W. Taylor, R. Dhanarajan, M. Seavy, and P. B. Chase (2006) Ca2+ sensitivity of regulated cardiac thin filament sliding does not depend on myosin isoform. Journal of Physiology 577: 935-944.
Schoffstall, B., A. Clark, and P. B. Chase (2006) Positive inotropic effects of low dATP/ATP ratios on mechanics and kinetics of porcine cardiac muscle. Biophysical Journal 91: 2216–2226.
Huang, L., P. Manandhar, K. Byun, P. B. Chase, and S. Hong (2006) Selective assembly and alignment of actin filaments with desired polarity on solid substrates. Langmuir 22: 8635-8638.
Moreno-Gonzalez , A., T. E. Gilles, A. J. Rivera, P. B. Chase, D. A. Martyn, and M. Regnier (2007) Thin filament regulation of force redevelopment kinetics in rabbit skeletal muscle fibres. Journal of Physiology 579: 313-326.
Kataoka, A., B. C. Tanner, J. M. Macpherson, X. Xu, Q. Wang, M. Regnier, T. L. Daniel, and P. B. Chase (2007) Spatially explicit, nano-mechanical models of the muscle half-sarcomere: Implications for biomechanical tuning in atrophy and fatigue. Acta Astronautica 60: 111-118.
Kataoka, A., C. Hemmer, and P. B. Chase (2007) Computational simulation of hypertrophic cardiomyopathy mutations in troponin I: influence of increased myocyte calcium sensitivity on isometric force, ATPase and [Ca2+]i. Journal of Biomechanics 40: 2044-2052.
Schoffstall, B., and P. B. Chase (2008) Increased intracellular [dATP] enhances cardiac contraction in embryonic chick cardiomyocytes. Journal of Cellular Biochemistry 104: 2217-2227.
Manandhar, P., K. Chen, K. Aledealat, G. Mihajlović, C. S. Yun, M. Field, G. S. Sullivan, G. F. Strouse, P. B. Chase, S. von Molnár, and P. Xiong (2009) The detection of specific biomolecular interactions with micro-Hall magnetic sensors. Nanotechnology 20: 355501.
Butcher, M. T., P. B. Chase, J. W. Hermanson, A. M. Clark, N. N. Brunet, and J. E. Betram (2010) Contractile properties of muscle fibers from the forelimb deep and superficial digital flexors of horses. American Journal of Physiology - Regulatory, Integrative and Comparative Physiology 299: R996-R1005.
Aledealat, K., G. Mihajlović, K. Chen, M. Field, G. J. Sullivan, P. Xiong, P. B. Chase, and S. von Molnár (2010) Dynamic micro-Hall detection of superparamagnetic beads in a microfluidic channel. Journal of Magnetism and Magnetic Materials 322: L69-L72.
Bai, F., A. Weis, A. K. Takeda, P. B. Chase, and M. Kawai (2011) Enhanced active cross-bridges during diastole: molecular pathogenesis of tropomyosin’s HCM mutations. Biophysical Journal 100: 1014-1023.
Mathur, M. C., P. B. Chase, and J. M. Chalovich (2011) Several cardiomyopathy causing mutations on tropomyosin either stabilize the inactive state or actomyosin or alter the binding properties of tropomyosin. Biochemical and Biophysical Research Communications 406: 74-78.
Cheng, Y., K. Chen, N. L. Meyer, J. Yuan, L. S. Hirst, P. B. Chase, and P. Xiong (2011) Functionalized SnO2 nanobelt field-effect transistor sensors for label-free detection of cardiac troponin. Biosensors and Bioelectronics 26: 4538-4544.
Schoffstall, B., V. A. LaBarbera, N. M. Brunet, B. J. Gavino, L. Herring, S. Heshmati, B. H. Kraft, V. Inchausti, N. L. Meyer, D. Moonoo, A. K. Takeda, and P. B. Chase (2011) Interaction between troponin and myosin enhances contractile activity of myosin in cardiac muscle. DNA and Cell Biology 30: 653-659.
Asumda, F. Z., and P. B. Chase (2011) Age-related changes in rat bone marrow mesenchymal stem cell plasticity. BMC Cell Biology 12: 44.
Wang, F., N. M. Brunet, J. R. Grubich, E. Bienkiewicz, T. M. Asbury, L. A. Compton, G. Mihajlović, V. F. Miller, and P. B. Chase (2011) Facilitated cross-bridge interactions with thin filaments by familial hypertrophic cardiomyopathy mutations in α-tropomyosin. Journal of Biomedicine and Biotechnology 2011: 435271.
Asumda, F. Z., and P. B. Chase (2012) Nuclear cardiac troponin and tropomyosin are expressed early in cardiac differentiation of rat mesenchymal stem cells. Differentiation 83: 106-115.
Chase, P. B., S. Hong, A. Månsson, and P. Xiong (2012) Editorial: Bionanotechnology and Nanomedicine. Journal of Biomedicine and Biotechnology 2012: 763967.
Hira, S. M., K. Aledealat, K. Chen, M. Field, G. J. Sullivan, P. B. Chase, P. Xiong, S. von Molnár, and G. F. Strouse (2012) Detection of target ssDNA using a micro-fabricated Hall magnetometer with correlated optical readout. Journal of Biomedicine and Biotechnology 2012: 492730.
Brunet, N. M., G. Mihajlović, K. Aledealat, F. Wang, P. Xiong, S. von Molnár, and P. B. Chase (2012) Micro-mechanical thermal assays of Ca2+-regulated thin filament function and modulation by hypertrophic cardiomyopathy mutants of human cardiac troponin. Journal of Biomedicine and Biotechnology 2012: 657523.
Loong, C. K., M. A. Badr, and P. B. Chase (2012) Tropomyosin flexural rigidity and single Ca2+ regulatory unit dynamics: implications for cooperative regulation of cardiac muscle contraction and cardiomyocyte hypertrophy. Frontiers in Physiology (Frontiers in Striated Muscle Physiology) 3: 80. [equal contributions by Loong and Badr]
Loong, C. K., H. Zhou, and P. B. Chase (2012) Persistence length of human cardiac α-tropomyosin measured by single molecule direct probe microscopy. PLoS One 7: e39676.
Loong, C. K., H. Zhou, and P. B. Chase (2012) Familial hypertrophic cardiomyopathy related E180G mutation increases flexibility of human cardiac α-tropomyosin. FEBS Letters 586: 3503-3507.
Loong, C. K., A. Takeda, M. A. Badr, J. S. Rogers, and P. B. Chase (2013) Slowed dynamics of thin filament regulatory units reduces Ca2+-sensitivity of cardiac biomechanical function. Cellular and Molecular Bioengineering . [In press; equal contributions by Loong and Takeda]
Karatzaferi, C., and P. B. Chase (2013) Editorial for Research Topic special issue: Muscle fatigue and muscle weakness: what we know and what we wish we did. Frotiers in Physiology (Frontiers in Striated Muscle Physiology) . [In press]