Cardiac myosin binding protein-C (cMyBP-C) is a trans-filament protein which, at its N'-region, connects thick and thin filaments to regulate cardiac contractility. The overall objective of the studies contained in this renewal of R01HL-105826 is to define the N'-region of cMyBP-C as a critical regulator of cardiac contractility. In particular, C0-C1f, which interacts only with actin, is generated by proteolysis of cMyBP-C during ischemia/reperfusion (I/R) injury and heart failure. On the other hand, C0-C2 interacts with both actin and myosin, connecting thin and thick filaments to regulate sarcomere function. On the basis of these findings, we will 1) use a novel transgenic mouse model expressing cMyBP-C (cMyBP-C110kDa) in which the C0-C1f region was ablated to study the necessity and sufficiency of this domain in regulating cardiac contractility and 2) use adeno-associated virus 9 (AAV9)-mediated expression of (i) recombinant C0-C2 to determine the sufficiency of N'-terminal C0-C2 in bundling thick and thin filaments in vivo and (ii) recombinant C0-C2?CTS, in which the calpain-targeted site (CTS) has been ablated, to determine its therapeutic potential in improving cardiac function pre- and post-I/R injury. The molecular mechanisms underlying the regulation of cMyBP-C and, in turn, its impact on sarcomere structure and function, are largely unknown. Our short-term goal is to elucidate the specific role(s) of the N'-region of cMyBP-C in the regulation of cardiac function, whereas our long-term goal is to determine the mechanisms by which cMyBP-C stabilizes sarcomeric structure and function, thereby conferring cardioprotection during I/R injury.
SPECIFIC AIM 1 will test the hypothesis that the C0-C1f domain of cMyBP-C, which is cleaved and released during I/R injury, is necessary for regulating cardiac function. Transgenic cMyBP-C110kDa mice will be used to determine the critical role of the N'-region of cMyBP-C at the sarcomere and whole-heart levels, compared to the control non-transgenic mice.
SPECIFIC AIM 2 will test the hypothesis that the C0-C2 domains of cMyBP-C are sufficient to bundle thick and thin filaments and to regulate normal cardiac function. AAV9-mediated expression of recombinant C0-C2 will be used to prevent or rescue contractile dysfunction in mouse models that lack either the N'-region (C0-C1f) or full-length cMyBP-C in vivo.
SPECIFIC AIM 3 will test the hypothesis that expression of recombinant C0-C2?CTS in vivo confers cardioprotection during I/R injury. Recombinant C0-C2?CTS protein is protected from calpain-mediated degradation. We expect AAV9-mediated expression of recombinant C0-C2?CTS to significantly reduce infarct size and apoptosis, as well as preserve contractile function during I/R injury. Together, these studies will determine the necessity and sufficiency of the N'-region (both C0-C1f and C0-C2) of cMyBP-C to regulate cardiac function, and, hence, provide therapy for myocardial injury and heart failure occurring during I/R injury.

Public Health Relevance

The long-term objective is to understand the functional consequences of cardiac myosin binding protein-C on heart function. In particular, the proposed studies will determine the specific role(s) of the amino terminal-region of cardiac myosin binding protein-C in regulating sarcomere structure and function at the cardiac sarcomeric and whole-heart levels, leading to the development of potential cardioprotective therapeutic approaches to improve cardiac function in heart failure.

Agency
National Institute of Health (NIH)
Institute
National Heart, Lung, and Blood Institute (NHLBI)
Type
Research Project (R01)
Project #
2R01HL105826-05A1
Application #
9104884
Study Section
Cardiac Contractility, Hypertrophy, and Failure Study Section (CCHF)
Program Officer
Adhikari, Bishow B
Project Start
2011-01-01
Project End
2020-02-28
Budget Start
2016-04-01
Budget End
2017-02-28
Support Year
5
Fiscal Year
2016
Total Cost
Indirect Cost
Name
Loyola University Chicago
Department
Physiology
Type
Schools of Medicine
DUNS #
791277940
City
Maywood
State
IL
Country
United States
Zip Code
60153
McNamara, James W; Sadayappan, Sakthivel (2018) Skeletal myosin binding protein-C: An increasingly important regulator of striated muscle physiology. Arch Biochem Biophys 660:121-128
Sadayappan, Sakthivel (2018) My Life, My Heart, and My(osin) Binding Protein-C. Circ Res 122:918-920
Viswanathan, Shiv Kumar; Puckelwartz, Megan J; Mehta, Ashish et al. (2018) Association of Cardiomyopathy With MYBPC3 D389V and MYBPC3?25bpIntronic Deletion in South Asian Descendants. JAMA Cardiol 3:481-488
McNamara, James W; Grimes, Kelly M; Sadayappan, Sakthivel (2018) Basic Cardiovascular Sciences Scientific Sessions 2018. Circ Res 123:1024-1029
Lin, Brian Leei; Song, Taejeong; Sadayappan, Sakthivel (2017) Myofilaments: Movers and Rulers of the Sarcomere. Compr Physiol 7:675-692
Lynch 4th, Thomas L; Kuster, Diederik W D; Gonzalez, Beverly et al. (2017) Cardiac Myosin Binding Protein-C Autoantibodies are Potential Early Indicators of Cardiac Dysfunction and Patient Outcome in Acute Coronary Syndrome. JACC Basic Transl Sci 2:122-131
Lynch 4th, Thomas L; Ismahil, Mohamed Ameen; Jegga, Anil G et al. (2017) Cardiac inflammation in genetic dilated cardiomyopathy caused by MYBPC3 mutation. J Mol Cell Cardiol 102:83-93
Viswanathan, Shiv Kumar; Sanders, Heather K; McNamara, James W et al. (2017) Hypertrophic cardiomyopathy clinical phenotype is independent of gene mutation and mutation dosage. PLoS One 12:e0187948
Sadayappan, Sakthivel (2017) The Myofilament Field Revisited in the Age of Cellular and Molecular Biology. Circ Res 121:601-603
Sadayappan, Sakthivel (2017) Cardiovascular Early Careers: Past and Present. Circ Res 121:100-102

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