Experiments proposed here test the hypothesis that modulation of the structure, activity, and isoform population of troponin (TnI) are important determinants of the relative susceptibility of hearts to injury resulting from ischemia/reperfusion. We have focused on TnI, a key thin filament regulatory protein, in view of evidence that the extent of ischemia/reperfusion injury has been correlated: 1) with cardiac development which involves isoform switching from the embryonic slow skeletal (ssTnI) to the adult cardiac (cTnI) isoform, 2) with specific proteolysis of TnI, and 3) with protein kinase (PKC) dependent phosphorylation of TnI. Our approach involves the use of hearts of two transgenic (TG) mouse models with specific and functionally significant alterations in TnI. One transgenic model (ssTnI- TG) expresses the embryonic/neonatal isoform, slow skeletal TnI (ssTnI), in place of adult cardiac TnI (cTnI). The other transgenic model (cTnIS43,45A- TG) express a mutant, in which functionally significant serine PKC sites have been rendered non-phosphorylatable by mutation to alanines.
The specific aims are:
Aim #1) to compare the effects of ischemia/reperfusion of pressure developed by NTG control hearts with both ssTnI-TG and cTnIS43,45A-TG hearts, Aim #2) to determine whether proteolytic breakdown of cTnI is altered in hearts containing myofilaments in which cTnI is replaced with either ssTnI or cTnIS43,45A, Aim #3) to determine whether the functional properties (pH, length dependence of Ca2+-activation and tension cost) of myofilaments isolated from hearts stressed by ischemia/reperfusion are altered differently in NTG and the two TG models, and Aim #4) to determine whether treatment of hearts with calcium-sensitizers (CGP 48506 and EMD 57033), alters the functional consequences of ischemia/reperfusion NTG and TG models. Experiments proposed here provide new evidence on the molecular basis of ischemia/reperfusion injury in both neonatal and adult myocardium. The results are also of significance with regard to the design of future therapies.

National Institute of Health (NIH)
National Heart, Lung, and Blood Institute (NHLBI)
Research Scientist Development Award - Research & Training (K01)
Project #
Application #
Study Section
Special Emphasis Panel (ZHL1-CSR-K (F1))
Program Officer
Commarato, Michael
Project Start
Project End
Budget Start
Budget End
Support Year
Fiscal Year
Total Cost
Indirect Cost
University of Illinois at Chicago
Schools of Medicine
United States
Zip Code
Jagatheesan, Ganapathy; Rajan, Sudarsan; Ahmed, Rafeeq P H et al. (2010) Striated muscle tropomyosin isoforms differentially regulate cardiac performance and myofilament calcium sensitivity. J Muscle Res Cell Motil 31:227-39
Jagatheesan, Ganapathy; Rajan, Sudarsan; Schulz, Emily M et al. (2009) An internal domain of beta-tropomyosin increases myofilament Ca(2+) sensitivity. Am J Physiol Heart Circ Physiol 297:H181-90
Warren, Chad M; Arteaga, Grace M; Rajan, Sudarsan et al. (2008) Use of 2-D DIGE analysis reveals altered phosphorylation in a tropomyosin mutant (Glu54Lys) linked to dilated cardiomyopathy. Proteomics 8:100-5
Jagatheesan, Ganapathy; Rajan, Sudarsan; Petrashevskaya, Natalia et al. (2007) Rescue of tropomyosin-induced familial hypertrophic cardiomyopathy mice by transgenesis. Am J Physiol Heart Circ Physiol 293:H949-58
Rajan, Sudarsan; Ahmed, Rafeeq P H; Jagatheesan, Ganapathy et al. (2007) Dilated cardiomyopathy mutant tropomyosin mice develop cardiac dysfunction with significantly decreased fractional shortening and myofilament calcium sensitivity. Circ Res 101:205-14
Arteaga, Grace M; Warren, Chad M; Milutinovic, Sanja et al. (2005) Specific enhancement of sarcomeric response to Ca2+ protects murine myocardium against ischemia-reperfusion dysfunction. Am J Physiol Heart Circ Physiol 289:H2183-92
Wolska, Beata M; Arteaga, Grace M; Pena, James R et al. (2002) Expression of slow skeletal troponin I in hearts of phospholamban knockout mice alters the relaxant effect of beta-adrenergic stimulation. Circ Res 90:882-8