Research Themes:
Biomaterials and Regenerative Medicine
Molecular and Cellular Engineering

Education

PhD (biology-neurobiology), University of Southern California, 1991
MS (exercise physiology), Portland State University, 1983
BA (history) and B.A. (political science), PSU, 1980

Research Interests

• Regulation of muscle contraction
   
• Chemo-mechanical transduction
  
• Neuromuscular plasticity

Contact Information

Department of Bioengineering
University of Washington
Box 355061
William H. Foege Building, Room N310F
Phone: 206-616-4325, 206-221-5763
Fax: 206-685-3300
E-mail
Web site: http://www.bioeng.washington.edu/regnier/

Research Description

The Heart And Muscle Mechanics (HAMM) lab uses basic research to understand both cardiac and skeletal muscle function, and applied research to understand and treat diseases.

Basic Research
The rate at which muscles can produce force or shorten is an important factor in the control of movement. These parameters are also important in cardiac contractions where they control the amount and rate of blood pumped by the heart.

At the cellular level the rates of muscle force development and shortening are determined by interactions of the proteins actin and myosin, and these interactions are fueled by the hydrolysis of ATP. This thermodynamic process of chemical energy conversion into mechanical work (chemo-mechanical transduction) is controlled by calcium binding to a group of regulatory proteins associated with actin.The mechanisms by which these proteins regulate muscle force and shortening are still poorly understood, however, due to the complex and cooperative interactions that occur during contractions. There is increasing evidence of significant differences between cardiac and skeletal muscle contractile regulation, which likely results from different isoforms of thick and thin filament proteins.

To study these questions we have developed a variety of molecular and cellular techniques.Caged compounds, pharmaceutical agents and mechanical transients are used to study actin-myosin interactions, the calcium binding dynamics of the regulatory proteins and the kinetic relationships between these two processes. We also extract native regulatory proteins from muscle and replace them with regulatory proteins modified by site-directed mutagenesis to determine how protein structure modifies contractile activation and kinetics. Site-directed mutants mimicking those found in cardiomyopathies are used as models for functional deficits with disease.

Labeling these proteins with fluorescent tags can give a detailed picture of the relationship between protein structure and function. Mechanical measurements are made from single, isolated cardiac and skeletal muscle cells. An exciting and correlative approach we employ is to make mechanical measurements from isolated contractile and regulatory proteins using sophisticated equipment that allows characterization of force and speed at the nano– and micro-scale.

The information gathered from these experiments is used to develop state of the art mathematical models of the relationship between protein structures and interactions, the contractile lattice geometry, chemo-mechanical transduction and the regulation of contraction by calcium.  We collaborate with the Daniel (Mathematical Biology) and Daggett (Bioengineering) labs on these projects, often using large computer clusters and cloud computing.  This research is important for simulation of protein engineering strategies to improve muscle performance and treatment of cardiac and skeletal muscle diseases.

Applied Research
Pathologies such as diabetes, hypertrophic cardiomyopathy, hypothyroidism and heart failure, as well as ischemia/reperfusion injury, involve alterations in the contractile and regulatory proteins of myocardium.

Changes in protein isoforms resulting from disease or mutation often impair cardiac function during normal activation of the heart or during strenuous activity. Similar types of contractile protein alterations are found in skeletal muscle diseases, such as distal arthrogryposis and idiopathic clubfoot. A long-term objective of our research is to use tools such as protein and tissue engineering to design effective preventions and therapies for cardiac and skeletal myopathies. 

In collaboration with the Murry and Ratner labs (and others), we are working on methods to improve cardiac function following myocardial infarct (heart attack). One experimental approach involves transplantation of cardiomyocytes or engineered tissue constructs into damaged regions. Ongoing experiments access cell survivability and contractile properties, effects on non-infarct regions and methods to improve the incorporation of transplanted cells into the host tissue. An additional exciting approach is to re-engineer sarcomere proteins and substrate conditions to improve the contractile function of diseased or failing cardiac and skeletal muscle.  These engineering proteins are currently being delivered using viral transfection strategies.

Honors & Awards

• American Heart Association Established Investigator

Selected Publications

• Stevens, K.R., K.L. Kreutziger, S.K. Dupras, F.S.  Korte, M. Regnier, V. Muskheli, M.B. Nourse, K. Bendixen, H. Reinecke, C.E. Murry. (In Press), Scaffold-free, Vascularized, Tissue-Engineered Human Cardiac Muscle: Physiological Function and Transplantation.  PNAS
• Moreno-Gonzalez, A., F. S. Korte, J. Dai, K. Chen, M. Schrader, B. Ho, H. Reinecke, C. E. Murry and M. Regnier (In Press), Neonatal cardiomyocytes transplanted into infarcted rat hearts mature, contract and enhance function of remote myocardium.  JMCC.  Pre-print available online.
• Smith, L., C. Tainter, M. Regnier and D. A. Martyn. (2009).  Cooperative crossbridge activation of thin filaments contributes to the Frank-Starling mechanism in cardiac muscle.  Biophys. J. 96:3692-3702.
• Razamova, M. V., K. L. Bezold, A. Tu, M. Regnier and S. P. Harris. (2008). Contribution of the myosin binding protein-C motif to functional effects in permeabilized rat trabeculae. J. Gen. Physiol. 132:575-585.
• Nitta, Takahiro, A. Tanahashi, Y. Obara, M. Hirano, M. Razumova, M. Regnier and H. Hess. (2008). Comparing guiding track requirements for myosin- and kinesin-powered molecular shuttles. Nano Letters Online at http://pubs.acs.org/cgi-bin/abstract.cgi/nalefd/asap/abs/nl8010885.html.
• Kreutziger, K. L., N. Piroddi, B. Scellini, C. Tesi, C. Poggesi and M. Regnier (2008). Thin filament Ca2+ binding properties and regulatory unit interactions alter kinetics of tension development and relaxation in rabbit skeletal muscle.  J.Physiol.  586:3683-3700.
• Tanner, B. C. W., M. Regnier and T. L. Daniel. (2008). A spatially-explicit model of muscle contraction explains a relationship between activation phase, power, and ATP utilization in insect flight.  J. Exp. Biol. 211:180-186.
• Kreutziger, K. L., T. E. Gillis, J. P. Davis, S. B. Tikunova and M. Regnier. (2007). Influence of enhanced troponin C Ca2+ binding affinity on cooperative thin filament activation in skeletal muscle. J. Physiol. 583:337-350.
• Tanner, B. C. W., T. L. Daniel and M. Regnier. (2007). Sarcomere lattice geometry influences cooperative myosin binding in spatially-explicit, compliant myofilament models. PLOS Comp. Biol. 3(7): e115 doi:10.1371/journal.pcbi.0030115.
• Shaffer, J. F., M. V. Razumova, A. Y. Tu, M. Regnier and S. P. Harris. (2007). Myosin S2 is not required for effects of cMyBP-C on motility.  FEBS Letters 581:1501-1504.
• Gillis, T. E., D. A. Martyn, A. J. Rivera and M. Regnier. (2007). Investigation of thin filament near-neighbor regulatory unit interactions during skinned cardiac and skeletal muscle force development. J. Physiol. 580:561-576
• Martyn, D. A., L. Smith, K. L. Kreutziger, S. Xu, L. C. Yu, and M. Regnier. (2007). The effects of force inhibition by sodium vanadate on crossbridge binding, tension development and Ca2+-activation in cardiac muscle. Biophys. J.92:1-12.
• Moreno-Gonzalez, A., T. E. Gillis, 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. J. Physiol.  579:313-326.
• Chase, P. B., A. Kataoka, B. C. W. Tanner, J. M. Macpherson, Xiagraong Xu, Q. Wang, M. Regnier and T. L. Daniel. (2007), Spatially explicit, nano-mechanical models of the muscle half-sarcomere: implications for biomechanical tuning in atrophy and fatigue.  Acta Astronautica.60:111-118.
• Razumova, M. V., J. F. Shaffer, A. Y. Tu, G. V. Flint, M. Regnier and S. P. Harris. (2006). Effects of N-terminal domains of myosin binding protein-C in an in vitro motility assay: evidence for long-lived cross bridges. J.Biol. Chem. 281:35846-35854.
• Bell, M. G., E. B. Lankford, G. E. Gonye, G. C. Ellis-Davies, M. Regnier, D. A. Martyn and R. J. Barsotti. (2006). Kinetics of cardiac thin-filament activation probed by fluorescence polarization of rhodamine-labeled troponin C in skinned guinea pig trabeculae. Biophys. J. 90:531-543.
• Clemmens, E. W., M. Entezari, D. A. Martyn, and M. Regnier. (2005). Different effects of cardiac vs. skeletal muscle regulatory proteins on in vitro measures of actin filament speed and force. J. Physiol. 566:737-46.
• Moreno-Gonzalez, A., J. Fredlund and M. Regnier. (2005). Cardiac TnC and a site I skeletal TnC mutant alter Ca2+ vs. crossbridge contribution to force development in rabbit skeletal fibres J. Physiol 562:873-884.
• Regnier, M., H. Martin, R. J. Barsotti, A. J. Rivera, D. A. Martyn, and E. Clemmens.  (2004). Crossbridge vs. thin filament contributions to the level and rate of force development in cardiac muscle.  Biophys. J. 87: 1815-18247.
• Gordon, A. M., E. Homsher and M. Regnier. (2000). Regulation of contraction in striated muscle. (Invited Review) Physiol. Rev. 80:853-924.
• Adhikari, B. B., M. Regnier, A. J. Rivera, K. L Kreutziger, and D. A. Martyn.  (2004). Cardiac length dependence of force and force redevelopment kinetics with altered crossbridge cycling.  Biophys J. 87: 1784-1794.
• Sieck, G. C. and M. Regnier. (2001). Plasticity and energetic demands of contraction in skeletal and cardiac muscle. (Invited Review). J. Applied Physiol. 90:1158-1164.
• Gordon, A.M., M. Regnier and E. Homsher. (2001). Skeletal and cardiac muscle contractile activation: tropomyosin ‘rocks and rolls’. (Invited Review). NIPS. 16:49-55.
• Regnier, M and E. Homsher. (1998). The effect of ATP analogues on post-hydrolytic and force development steps in skinned skeletal muscle fibers. Biophys. J. 74:3059-3071.
• Regnier, M., D. M. Lee, and E. Homsher. (1998). ATP analogues as substrates for muscle contraction: Muscle mechanics and kinetics of nucleoside triphosphate binding and hydrolysis.  Biophys. J. 74:3044-3058.