Curriculum Vitae
BS George Washington University 1965
Ph.D University of Connecticut 1970
Postdoc. Muscle Biochemistry and Biophysics (with Professor John Gergely) Boston Biomedical Research Institute 1970-1974
Associate in Neurology, Harvard Medical School 1974-1975
Assistant Professor, Department of Cell Biophysics, Baylor College of Medicine 1975-1977
Associate Professor, Department of Pharmacology and Cell Biophysics, University of Cincinnati 1977-1981
Professor, University of Cincinnati, 1981-1983
Chairman, Department of Molecular & Cellular Pharmacology, University of Miami Miller School of Medicine 1983-2008
Professor, Department of Molecular & Cellular Pharmacology, University of Miami Miller School of Medicine 1983-present
Senior Advisor to the Dean, University of Miami, Miller School of Medicine 2008-present
THE LABORATORY OF JAMES D. POTTER, Ph.D /
DANUTA SZCZESNA-CORDARY, Ph.D.
Pictured from left-right, front row, Yingcai Wang, Fatima deFreitas, Danuta Szczesna-Cordary (PI), James D. Potter (PI) Michelle Jones, Michelle Parvatiyar, José Renato Pinto; second row, Jiang-Sheng Liang, Zoraida Diaz-Perez, Elba Lalor, Yuhui Wen, Georgianna Guzman, Sherlley Sanon, Sanjeev Sirpal, David Dweck, Hannah Wasserman..
RESEARCH PROJECTS IN THE LABORATORY OF
JAMES D. POTTER, Ph.D.
Personnel: Faculty: James D. Potter, Ph.D.(PI), Danuta Szczesna-Cordary, Ph.D. (PI), Associate Professor, Yingcai Wang, Ph.D., Assistant Professor
 Research Associates: Michelle Jones, Jiang-Sheng Liang
Postdoctoral Fellows: David Dweck, Ph.D., José Renato Pinto, Ph.D.
Graduate Students: Michelle Parvatiyar
Undergraduate Students: Sherlley Sanon (University of Miami)
High School Students: Erin Alexander
Collaborators: Michael Ackerman, M.D., Ph.D. (Mayo Clinic), Christopher Ashley, Ph.D. (Oxford University), Nanette Bishopric, M.D. (University of Miami), Jonathan Davis, Ph.D. (Ohio State University), Aldrin Gomes, Ph.D. (University of California, Davis), Bjorn C. Knollmann, M.D./Ph.D. (Vanderbilt University), Joseph Metzger, Ph.D., (University of Michigan), Franklyn Prendergast, M.D./Ph.D. (Mayo Clinic), Keith Webster, Ph.D. (University of Miami).
The major theme of the lab’s current research projects is the study of the cellular signaling events associated with the regulation of cardiac and skeletal muscle contraction in normal and pathological states. The lab currently has three NIH grants, and the abstracts from these grants are listed below:
Cardiac Troponin in Health and Disease
The overall goal of the proposed studies is to eluicidate the molecular mechanisms involved in the regulation of cardiac muscle contraction by troponin (Tn) in health and disease. The current proposal will determine the effect of mutations in cTnT, cTnI and cTnC, known to cause familial hypertrophic cardiomyopathy (FHC or HCM), dilated cardiomyopathy (DCM) and restrictive cardiomyopathy (RCM) on the biochemical, contractile and electrophysiological properties of cardiac muscle. Knock-in mice will be generated expressing cTn subunits that contain mutations known tu cause HCM, DCM and RCM in man and the morphological and in vitro and in vivo properties of these cardiac disease states will be investigated. The following Specific Aims will be pursued:
Specific Aim 1: Physiological Consequences of Troponin - Mediated Genetic Disorders Studied in the HCM, DCM, and RCM Mouse Models. We propose to utilize the following knock-in mice (five of these six have already been produced) to study these three types of cardiomyopathy: (A) HCM: cTnI-R21C and cTnT-R92W; (B) DCM: cTnI- D K183 and cTnT-R141W and (C) RCM: cTnI-K178E and cTnI-R145W. We will perform: i) Biochemical characterization; ii) Fiber studies (to establish Ca 2+ sensitivity of ATPase/force and g app); iii) Force and intracellular [Ca 2+] transients; iv) Tissue analysis; and v) Physiological and electrophysiological characterization.
Specific Aim 2: Elucidate the Role that Troponin C, A Molecular Ca 2+ Switch Plays in HCM, DCM AND RCM. The following mutant cTnC knock-in mice are proposed for this study: cTnC-S37G (HCM), cTnC-F20Q (DCM) and cTnC-V44Q (RCM). If, as we hypothesize, cTnC is ultimately responsible for the calcium dependent phenotypic properties underlying HCM, DCM and RCM that are caused by the mutations in either cTnC or TnT and/or TnI, one would expect that making these knock-in mutations in cTnC that alter its Ca 2+ binding affinity and/or other contractile properties of muscle, would prodouce phenotypes in proposed knock-in mice that are similar to those seen in man.
Specific Aim 3: Analysis of the Physiological Measurements in Aim 1 and 2 will be Utilized to Propose Unifying Theories of Mechanisms Responsible for HCM, RCM and DCM. A comprehensive theory or theories regarding the mechanisms responsible for HCM, DCM and RCM will be proposed. We will evaluate the data and group the results according to various cardiomyopathies. The results will be further analyzed for correlations that deine characteristics of HCM, RCM and DCM. Our multidimensional approach will allow elucidation of the mechanisms that are responsible for specific myopathies and the determination of the severity of specific mutations that cause malignant phenotypes and SCD in man. These studies will be critical in understanding the effect these genetic structural changes have on cardiac muscle and how they might lead to the three distinctive disease states.
The Function of Slow Skeletal TnT in Muscle Contraction
The overall goal of the proposed experiments is to determine the molecular mechanisms involved in the regulation of slow skeletal muscle contraction by troponin T (TnT) and to determine what regions of TnT are important for its physiological function. To accomplish this overall goal we will carry out two specific aims:
Specific Aim 1. The Role Of Slow Skeletal Troponin T Isoforms In The Regulation Of Muscle Contraction. Essentially nothing is known about the regulation of slow skeletal muscle by troponin T (TnT) and this is the prime focus of our study which will thoroughly investigate the function of slow skeletal muscle TnT (SSTnT) in the regulation of striated muscle contraction. The main hypothesis to be tested here is that the various N-terminal SSTnT isoforms modulate Ca2+-sensitivity and the relaxation properties of slow skeletal muscle contraction. We will answer the following questions: 1) Is the Ca2+-sensitivity of force development and/or ATPase activity affected by the N- or C-terminal regions of SSTnT? 2) Do SSTnT isoforms directly affect the affinity of TnC for Ca2+ or is there an indirect effect of SSTnT on the Ca2+ sensitivity of contraction (e.g., thin filament or crossbridge effect)? 3) Do the different SSTnT isoforms interact differently with tropomyosin? 4) Do SSTnT isoforms affect the activation and relaxation of force in skinned muscle fibers? 5) Are there other isoforms of SSTnT that have not been previously described? These studies will determine the role of the N-and C-terminal alternatively spliced regions of SSTnT on slow skeletal muscle contraction.
Specific Aim 2. The Role Of Different Regions Of Slow Skeletal Troponin T In The Physiological Function Of Troponin T. To understand the role of different regions of TnT we will carry out the following: 1) Characterization of the region of SSTnT that is important for Ca2+-independent ATPase activity. 2) Characterization of the region(s) of SSTnT that interacts with SSTnI, CTnC (same isoform in slow skeletal and cardiac muscle) and tropomyosin. 3) Investigation of the importance of SSTnI in the function of SSTnT. No functional studies on any region of SSTnT have so far been reported. All the Specific Aims listed above focus on gaining a more detailed understanding of the role of SSTnT in slow skeletal muscle contraction, including the molecular mechanisms of SSTnT-linked activation of muscle contraction.
HTS for Regulated Muscle Thin Filament Function
A hallmark of sarcomeric gene mutations in cardiomyopathies is their ability to alter the calcium regulation of cardiac muscle contraction. In general, the Ca2+ sensitivity of contraction decreases in dilated (DCM) cardiomyopathy; whereas, in hypertrophic (HCM) and restrictive (RCM) cardiomyopathies, the sensitivity increases. Since multiple forms of cardiomyopathies exist, the identification of new drugs that sensitize (+) or desensitize (–) the Ca2+ sensitivity could potentially reverse (+ or –) these aberrant changes. Therefore, the goal of this proposal is to use high throughput screening (HTS) to identify small molecules that can modulate the Ca2+ sensitivity of cardiac muscle contraction. To achieve this, we will use a model system composed of cardiac muscle regulated thin filaments (RTF) which are comprised of F-actin, tropomyosin and troponin (Tn). The RTF in combination with myosin (thick filament) make up the major proteins found in the contractile apparatus. In the absence of myosin, the RTF retains all of the Ca2+ regulated functions critical for muscle activation and relaxation. The proposed assay will use cardiac Tn (CTn) complexes that contain fluorescently labeled troponin C (CTnC), the Ca2+ binding subunit of the CTn complex. This will allow us to monitor changes in RTF fluorescence that occur when Ca2+ binds to the CTnC regulatory site. Therefore, detecting an increase or decrease (+ or –) in the labeled RTF fluorescence intensity at a fixed [Ca2+] and wavelength in response to a compound or “hit” from the HTS screen will indicate that a change (+ or –) in the apparent Ca2+ affinity of CTnC has occurred. Hits from the HTS will be further validated using two biological secondary screens. Based on the above, the RTF system can provide a robust, stable and physiological assay to identify compounds that specifically alter the RTF Ca2+ sensitivity and not the force via crossbridge-drug interactions. To achieve our goals, this proposal will pursue two Specific Aims. Knowledge gained from these studies can uncover potentially new pharmacological agents for the investigation and treatments of cardiomyopathies, hypertension and other forms of cardiovascular diseases.
Recent References
Szczesna, D., Zhang, R., Zhao, J., Jones, M. and Potter, J.D.: The Role of the NH2- and COOH-terminal Domains of the Inhibitory Region of TnI in the Regulation of Skeletal Muscle Contraction. J. Biol. Chem., 274:1999, pp.29536-29542.
Lipscomb, S., Palmer, R.E., Li, Q., Allhouse, L.D., Miller, T., Potter, J.D., and Ashley, C.C.: A Diazo-2 Study of Relaxation Mechanisms in Frog and Barnacle Muscle Fibres: effects of pH, MgADP, and Inorganic Phosphate. Pflugers Arch. 437:1999, pp. 204-212.
Pan, B-S., Housmans, P.R., Hannon, J.D., Wiedmann, R., Potter, J.D., Kranias, E.G., Shen, Y-T., and Johnson, Jr., R.G., Housmans, P.R. Effects of Isoproterenol on Twitch Contraction of Wild Type and Phospholamban-Deficient Murine Ventricular Myocardium. J. Mol. Cell Cardiol.31:1999, pp. 159-166.
Allhouse, L.D., Potter, J.D. and Ashley, C.C: A Novel Method of Extraction of TnC from Skeletal Muscle Myofibrils. Pflugers Arch (Eur. J. Physiol) 437:1999, pp.695-701.
Moncrieffe, M.C., Eaton, S., Bajzer, Z., Haydock, C., Prendergast, F.G., Potter, J.D. and Laue, T.M.: Rotational and Translational Motion of Troponin C. J. Biol. Chem., 274:1999, pp.17464-17470.
Allhouse, L.D., Guzman, G., Miller, T., Potter, J.D., Li, Q. and Ashley, C.C.: Characterisation of a Mutant of Barnacle Troponin C Lacking Ca2+ Binding Sites at Positions II and IV. Pflugers Arch. (European J. Physiol.) 438:1999, pp.30-39.
Cates, M.S., Berry, M.B., Ho, E.L., Li, Q., Potter, J.D., and Phillips, G.N.: Metal Ion Affinity and Specificity in EF-Hand Proteins: Coordination Geometry and Domain Plasticity in Parvalbumin. Structure Fold Des 7:1999, pp.1269-1278.
Moncrieffe, M.C., Venyaminov, S.Y., Miller, T.E., Guzman, G., Potter, J.D., and Prendergast, F.G.: Optical Spectroscopic Characterization of Single Tryptophan Mutants of Chicken Skeletal Troponin C: Evidence for Inter-domain Interaction. Biochemistry 38:1999, pp.11973-11983.
Szczesna, D., Zhang, R., Zhao, J., Jones, M., Guzman, G. and Potter, J.D.: Altered Regulation of Cardiac Muscle Contraction by Troponin T Mutations that Cause Familial Hypertrophic Cardiomyopathy. J. Biol. Chem. 276: 2000, 624-30.
Moncrieffe, M.C., JuranR c, N., Kemple, M.D., Potter, J.D., Macura, S. and Prendergast, F.G. Structure Fluorescence Correlations in a Single Tryptophan Mutant of Carp Parvalbumin: Solution Structure, Backbone and Sidechain Dynamics. J.Mol. Biol. 297: 2000, 147-63.
Allhouse, L.D., Guzman, G., Li, Q., Miller, T., Lipscomb, S., Potter, J.D., and Ashley, C.C. Investigating the Role of Ca2+-binding Site IV in Barnacle Troponin C. Pflugers Arch. 439: 2000, 600-9.
Kischel, P., Bastide, B., Potter, J.D. and Mounier, Y. The Role of the Ca2+ Regulatory Sites of Skeletal Troponin C in Modulating Muscle Fibre Reactivity to the Ca2+ Sensitizer Bepridil. Br. J. Pharmacol. 131: 2000, 1496-502.
Szczesna, D., Ghosh, D., Li, Q., Gomes, A.V., Guzman, G., Arana, C., Zhi, G., Stull, J.T., Potter, J.D. Abnormal Familial hypertrophic cardiomyopathy mutations in the regulatory light chains of myosin affect their structure, Ca2+ binding and phosphorylation. J. Biol. Chem. 276: 2001, 7086-92.
Miller, T., Szczesna, D., Housmans, P.R., Zhao, J., de Freitas, F., Gomes, A.V., Culbreath, L., McCue, J., Wang, Y., Xu, Y., Kerrick, W.G. and Potter, J.D. Abnormal Contractile Function in Transgenic Mice Expressing an FHC-Linked Troponin T (I79N) Mutation. J. Biol. Chem. 276: 2001, 3743-55.
Knollmann, B.C., Groth, A., Horton, K., de Freitas, F., Miller, T., Bell, M., Morad, M., Weissman, N.J., and Potter, J.D. Inotropic stimulation induces cardiac dysfunction in transgenic mice expressing a troponin T (I79N) mutation linked to familial hypertrophic cardiomyopathy. J. Biol. Chem. 276: 2001, 10039-48.
Christenson, R.H, Duh, S.H., Apple, F.S., Bodor, G.S., Bunk, D.M., Dalluge, J., Panteghini, M., Potter, J.D., Welch, M.J.,Wu, A.H, and Kahn, S.E. Standardization of cardiac troponin I assays: round Robin of ten candidate reference materials. Clin. Chem. 47: 2001, 431-7.
Hernandez, O.M., Housmans, P.R., and Potter, J.D. Invited Review: pathophysiology of cardiac muscle contraction and relaxation as a result of alterations in thin filament regulation. J. Appl. Physiol. 90: 2001, 1125-36.
Harada, K., Arana, C., and Potter, J.D. Magnesium-calcium exchange with the high affinity Ca2+-Mg2+ binding sites of cardiac troponin. J Mol Cell Cardiol 33: 2001, 593-6.
Knollmann B.C. and Potter J. D. Altered Regulation of Cardiac Muscle Contraction by Troponin T Mutations that cause Familial Hypertrophic Cardiomyopathy. Trends Cardiovascular Medicine 11:2001, 206-12.
Szczesna, D. and Potter, J.D.: The Role of Troponin in the Ca2+-Regulation of Skeletal Muscle Contraction. Results Probl Cell Differ 36;2002, 171-90.
Szczesna, D., Jones, M., Zhao, J., Zhi, G., Stull, J.T. and Potter, J.D. Phosphorylation of the Regulatory Light Chains of Myosin Affects Ca2+ Sensitivity of Skeletal Muscle Contraction. J. Appl. Physiol. 92:2002, 1661-70.
Lang, R., Gomes, A.V., Zhao, J., Miller, T., Housmans, P.R. and Potter, J.D. Functional Analysis of a Troponin I Mutation Associated with Hypertrophic Cardiomyopathy. J. Biol. Chem., 277:2002, 11670-8.
Gomes, A.V., Harada, K., and Potter, J.D. Cation Signaling in Striated Muscle Contraction. R. Solaro and R.L. Moss (eds), Molecular Control of Mechanisms in Striated Muscle Contraction. Klumer Academic Publishers. 2002, 163-197.
Gomes, A.V., Potter, J.D. The role of troponins in muscle contraction. IUBMB Life 54:2002, 322-33.
Gomes, A.V., Guzman, G., Zhao, J., Potter, J.D. Cardiac troponin T isoforms affect the Ca2+ sensitivity and inhibition of force development. Insights into the role of troponin T isoforms in the heart. J. Biol. Chem. 277;2002, 35341-9.
Knollmann, B.C., Kirchhof, P., Sirenko, S.G., Degen, H., Greene, A.E., Schober, T., Mackow, J.C., Fabritz, L, Potter, J.D., Morad, M. Familial hypertrophic cardiomyopathy-linked mutant troponin T causes stress-induced ventricular tachycardia and Ca2+-dependent action potential remodeling. Circ. Res. 92;2003, 428-36.
Venkatraman, G., Harada, K., Gomes, A.V., Kerrick, G.W., Potter, J.D. Different functional properties of Troponin T mutants that cause dilated cardiomyopathy . J. Biol. Chem. 278; 2003, 41670-41676.
Harada, K., Potter, J.D. FHC Mutations from Different Functional Regions of Troponin T Result in Different Effects on the pH- and Ca2+- Sensitivity of Cardiac Muscle contraction . J. Biol. Chem. 279; 2004, 14488-14495.
Gomes, A.V., Potter, J.D. Molecular and Cellular Aspects of Troponin Cardiomyopathies. Ann. New York Acad. Sci. 1015; 2004, 214-224.
Gomes, A.V. and Potter, J.D. Cellular and Molecular Aspects of Familial Hypertrophic Cardiomyopathy caused by Mutations in the Cardiac Troponin I Gene. Mol. & Cell. Biochem., 263:99-114, 2004.
Gomes, A.V., Barnes, J.A., Harada, K. and Potter, J.D.The Role of Troponin T in Disease. Mol. & Cell. Biochem., 263:115-129, 2004.
Gomes, A.F., Venkatraman, G. Davis, J.P., Tikunova, S.B., Engel, P., Solaro, R.J. and Potter, J.D.Cardiac Troponin T Isoforms affect the Ca 2+ Sensitivity of Force Development in the presence of Slow Skeletal Troponin I: Insights into the Role of Troponin T isoforms in the Fetal Heart.
J. Biol. Chem., 279 (48):49579-49587, 2004
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Blunt, B.C., Chen, Y., Potter, J.D. and Hoffman, P.A. Modest actomyosin energy conservation increases myocardial postischemic function. Amer. J. of Phys.288:H1088-H1096, 2005.
Dweck, D., Reyes-Alfonso, Jr., A. and Potter, J.D. Expanding the Range of Free Calcium Regulation in Biological Solutions. Analytical Biochem:303-15, 2005.
Gomes, A.V., Harada, K. and Potter, J.D. A mutation in the N-terminus of Troponin I that is associated with Hypertrophic cardiomyopathy affects the Ca2+-sensitivity phosphorylation kinetics and proteolytic susceptibility of troponin. J. Mol. & Cell. Card. 39:754-65, 2005.
Hernandez, O., Szczesna-Cordary, D., Miller, T., Zhao, J., Knollmann, B.C., Sirenko, S.G., Diaz, Z., Guzman, G., Xu, Y., Wang, Y., Kerrick, W.G.L. and Potter, J.D. F1101 and R278C Troponin T Mutations that Cause Familial Hypertrophic Cardiomyopathy Affect Muscle Contraction in Transgenic Mice and Reconstituted Human Cardiac Fibers. J. Biol. Chem. 280:37183-37194, 2005
Chang, A.N., Harada K., Ackerman, and Potter, J.D. Functional Consequence of Familial Hypertrophic and Dilated Cardiomyopathy Causing Mutations in α-Tropomyosin. J. Biol. Chem. 280:34343-34349, 2005
Gomes, A.V., Liang, J. and Potter, J.D. Mutations in Human Cardiac Troponin I that are associated with Restrictive Cardiomyopathy affect basal ATPase Activity and the Calcium Sensitivity of Force Development. J. Biol. Chem. 280:30909-30915, 2005.
Venkatraman, G., Gomes, A.V., Kerrick, G.W. and Potter, J.D. Characterization of Troponin T Dilated Cardiomyopathy Mutations in the Fetal Troponin Isoform.
J. Biol. Chem.280:17584-17592, 2005.
Blunt, B.C., Chen, Y., Potter, J.D. and Hofmann, P.A. Modest actomyosin energy conservation increases myocardial postischemic function.
Amer. J. of Phys.288:H1088-H1088-1096, 2005.
Westermann, D., Knollmann, B.C., Steendijk, P., Potter, J.D., Schultheiss, H-P and Tschöpe, C. Diltiazem treatment prevents diastolic heart failure in mice with familial hypertrophic cardiomyopathy. Eur. J. Heart Fail. 8:115-21, 2006.
Sirenko, S.G., Potter, J.D. and Knollmann, B.C. Differential Effect of Troponin T Mutations on the Inotropic Responsiveness of Mouse Hearts – Role of Myofilament Ca2+ Sensitivity Increase. J. Physiol. 575:201-213, 2006.
Wang, Y., Szczesna-Cordary, D., Craig, R., Diaz-Perez, Z., Guzman, G., Miller, T. and Potter, J.D. Fast Skeletal Muscle Regulatory Light Chain is Required for Fast and Slow Skeletal Muscle Development. FASEB J., 21:2205-2214, 2007.
Rodenbaugh, D., Wang, W., Davis, J., Edwards, T., Potter, J.D. and Metzger, J. Parvalbumin Isoforms Differentially Accelerate Cardiac Myocyte Relaxation Kinetics in an Animal Model of Diastolic Dysfunction.Am J Physiol Heart Circ Physiol 293:H1705-1713, 2007.
Shen, X., Franzini-Armstrong, C., Lopez, J.R., Jones, L.R., Kobayashi, Y.M., Wang, Y., Kerrick, W.G.L., Caswell, A.H., Potter, J.D., Miller, T., Allen, P.D. and Perez, C.F. Triadins Modulate Intracellular Ca2+ Homeostasis but are not Essential for Excitation-Contraction Coupling in Skeletal Muscle. J. Biol. Chem. 282(52):37864-74, 2008.
Lounes, K.C., Demeler, B., Anderson, D.E., Gomes, A.W., Potter, J.D., Nassar, R. and Anderson, P.A.W. Cardiac Troponin T Forms a Tetramer In Vitro.. Biochem. 47(7):1970-1976, 2008.
Pinto, J.R., Parvatiyar, M.S., Jones, M.A., Liang, J. and Potter, J.D. A Troponin T Mutation that Causes Infantile Restrictive Cardiomyopathy Increases Ca2+ Sensitivity of Force Development and Impairs the Inhibitory Properties of Troponin. J. Biol. Chem. 283(4):2156-66, 2008
Chang, A.N., Parvatiyar, M.S. and Potter, J.D. Troponin and Cardiomyopathy. Biochem. & Biophys. Res. 369:74-81 2008.
Wen, Y., Pinto, J.R., Gomes, A.V., Xu, Y., Wang, Y., Wang, Y., Potter, J.D. and Kerrick, W.G.L. Functional Consequences of the Human Cardiac Troponin I Hypertrophic Cardiomyopathy Mutation R145G in Transgenic Mice. J Biol. Chem. (In Press), 2008.
Landstrom, A.P., Parvatiyar, M.S., Pinto, J.R., Marquardt, M.L., Bos, J.M., Tester, D.J., Ommen, S.R., Potter, J.D. and Ackerman, M.J. Molecular and functional characterization of novel hypertrophic cardiomyopathy susceptibility mutations in TNNC1-encoded troponin C.. JMCC (In Press), 2008.
Dweck, D., Hus, N. and Potter, J.D. Challenging current paradigms related to cardiomyopathies: Are changes in the Ca2+ sensitivity from myofilaments containing cardiac troponin C mutations (G159D and L29Q) good predictors of the phenotypic outcomes? J. Bio. Chem. (In Press), 2008.
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