Abstract
Recently, it has been reported that the protein kinase C (PKC) beta isoform plays a critical role in the development of hypertrophy and heart failure. The purpose of the present study was to clarify the mechanism by which activation of PKCbeta led to depressed cardiac function. Thus, we used a PKCbeta2 overexpressing mouse, an animal model of heart failure, to examine mechanical properties and Ca2+ signals of isolated left ventricular cardiomyocytes. The percentage of shortening, rate of shortening, and rate of relengthening of cardiomyocytes were markedly reduced in PKCbeta2 overexpression mice compared to wild-type control mice, although the baseline level and amplitude of Ca2+ signals were similar. These findings suggested a decreased myofilament responsiveness to Ca2+ in transgenic hearts. Therefore, the incorporation of [32P] inorganic phosphate into cardiac myofibrillar proteins was studied in Langendorff-perfused hearts. There was a significant increase in the degree of phosphorylation of troponin I in PKCbeta2-overexpressing transgenic mice. The depressed cardiomyocyte function improved after the superfusion of a PKCbeta selective inhibitor. These findings indicate that in vivo PKCbeta2-mediated phosphorylation of troponin I may decrease myofilament Ca2+ responsiveness, and thus causes cardiomyocyte dysfunction. Since chronic and excess activation of PKCbeta2 plays a direct and contributory role in the progression of cardiac dysfunction, the PKCbeta selective inhibitor may provide a new therapeutic modality in the setting of heart failure.
Full Text
The Full Text of this article is available as a PDF (226.4 KB).
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Akella A. B., Ding X. L., Cheng R., Gulati J. Diminished Ca2+ sensitivity of skinned cardiac muscle contractility coincident with troponin T-band shifts in the diabetic rat. Circ Res. 1995 Apr;76(4):600–606. doi: 10.1161/01.res.76.4.600. [DOI] [PubMed] [Google Scholar]
- Bell D. S. Diabetic cardiomyopathy. A unique entity or a complication of coronary artery disease? Diabetes Care. 1995 May;18(5):708–714. doi: 10.2337/diacare.18.5.708. [DOI] [PubMed] [Google Scholar]
- Chu G., Dorn G. W., 2nd, Luo W., Harrer J. M., Kadambi V. J., Walsh R. A., Kranias E. G. Monomeric phospholamban overexpression in transgenic mouse hearts. Circ Res. 1997 Oct;81(4):485–492. doi: 10.1161/01.res.81.4.485. [DOI] [PubMed] [Google Scholar]
- D'Angelo D. D., Sakata Y., Lorenz J. N., Boivin G. P., Walsh R. A., Liggett S. B., Dorn G. W., 2nd Transgenic Galphaq overexpression induces cardiac contractile failure in mice. Proc Natl Acad Sci U S A. 1997 Jul 22;94(15):8121–8126. doi: 10.1073/pnas.94.15.8121. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Edes I., Kranias E. G. Phospholamban and troponin I are substrates for protein kinase C in vitro but not in intact beating guinea pig hearts. Circ Res. 1990 Aug;67(2):394–400. doi: 10.1161/01.res.67.2.394. [DOI] [PubMed] [Google Scholar]
- Fabiato A., Fabiato F. Effects of pH on the myofilaments and the sarcoplasmic reticulum of skinned cells from cardiace and skeletal muscles. J Physiol. 1978 Mar;276:233–255. doi: 10.1113/jphysiol.1978.sp012231. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Fan D., Wannenburg T., de Tombe P. P. Decreased myocyte tension development and calcium responsiveness in rat right ventricular pressure overload. Circulation. 1997 May 6;95(9):2312–2317. doi: 10.1161/01.cir.95.9.2312. [DOI] [PubMed] [Google Scholar]
- Gao W. D., Atar D., Liu Y., Perez N. G., Murphy A. M., Marban E. Role of troponin I proteolysis in the pathogenesis of stunned myocardium. Circ Res. 1997 Mar;80(3):393–399. [PubMed] [Google Scholar]
- Gu X., Bishop S. P. Increased protein kinase C and isozyme redistribution in pressure-overload cardiac hypertrophy in the rat. Circ Res. 1994 Nov;75(5):926–931. doi: 10.1161/01.res.75.5.926. [DOI] [PubMed] [Google Scholar]
- Gunteski-Hamblin A. M., Song G., Walsh R. A., Frenzke M., Boivin G. P., Dorn G. W., 2nd, Kaetzel M. A., Horseman N. D., Dedman J. R. Annexin VI overexpression targeted to heart alters cardiomyocyte function in transgenic mice. Am J Physiol. 1996 Mar;270(3 Pt 2):H1091–H1100. doi: 10.1152/ajpheart.1996.270.3.H1091. [DOI] [PubMed] [Google Scholar]
- Gwathmey J. K., Hajjar R. J. Effect of protein kinase C activation on sarcoplasmic reticulum function and apparent myofibrillar Ca2+ sensitivity in intact and skinned muscles from normal and diseased human myocardium. Circ Res. 1990 Sep;67(3):744–752. doi: 10.1161/01.res.67.3.744. [DOI] [PubMed] [Google Scholar]
- Inoguchi T., Battan R., Handler E., Sportsman J. R., Heath W., King G. L. Preferential elevation of protein kinase C isoform beta II and diacylglycerol levels in the aorta and heart of diabetic rats: differential reversibility to glycemic control by islet cell transplantation. Proc Natl Acad Sci U S A. 1992 Nov 15;89(22):11059–11063. doi: 10.1073/pnas.89.22.11059. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Ishii H., Jirousek M. R., Koya D., Takagi C., Xia P., Clermont A., Bursell S. E., Kern T. S., Ballas L. M., Heath W. F. Amelioration of vascular dysfunctions in diabetic rats by an oral PKC beta inhibitor. Science. 1996 May 3;272(5262):728–731. doi: 10.1126/science.272.5262.728. [DOI] [PubMed] [Google Scholar]
- Ito N., Kagaya Y., Weinberg E. O., Barry W. H., Lorell B. H. Endothelin and angiotensin II stimulation of Na+-H+ exchange is impaired in cardiac hypertrophy. J Clin Invest. 1997 Jan 1;99(1):125–135. doi: 10.1172/JCI119123. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Jideama N. M., Noland T. A., Jr, Raynor R. L., Blobe G. C., Fabbro D., Kazanietz M. G., Blumberg P. M., Hannun Y. A., Kuo J. F. Phosphorylation specificities of protein kinase C isozymes for bovine cardiac troponin I and troponin T and sites within these proteins and regulation of myofilament properties. J Biol Chem. 1996 Sep 20;271(38):23277–23283. doi: 10.1074/jbc.271.38.23277. [DOI] [PubMed] [Google Scholar]
- Kadambi V. J., Ponniah S., Harrer J. M., Hoit B. D., Dorn G. W., 2nd, Walsh R. A., Kranias E. G. Cardiac-specific overexpression of phospholamban alters calcium kinetics and resultant cardiomyocyte mechanics in transgenic mice. J Clin Invest. 1996 Jan 15;97(2):533–539. doi: 10.1172/JCI118446. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Khoury S. F., Hoit B. D., Dave V., Pawloski-Dahm C. M., Shao Y., Gabel M., Periasamy M., Walsh R. A. Effects of thyroid hormone on left ventricular performance and regulation of contractile and Ca(2+)-cycling proteins in the baboon. Implications for the force-frequency and relaxation-frequency relationships. Circ Res. 1996 Oct;79(4):727–735. doi: 10.1161/01.res.79.4.727. [DOI] [PubMed] [Google Scholar]
- Kiss E., Ball N. A., Kranias E. G., Walsh R. A. Differential changes in cardiac phospholamban and sarcoplasmic reticular Ca(2+)-ATPase protein levels. Effects on Ca2+ transport and mechanics in compensated pressure-overload hypertrophy and congestive heart failure. Circ Res. 1995 Oct;77(4):759–764. doi: 10.1161/01.res.77.4.759. [DOI] [PubMed] [Google Scholar]
- Le Prigent K., Lagadic-Gossmann D., Feuvray D. Modulation by pH0 and intracellular Ca2+ of Na(+)-H+ exchange in diabetic rat isolated ventricular myocytes. Circ Res. 1997 Feb;80(2):253–260. doi: 10.1161/01.res.80.2.253. [DOI] [PubMed] [Google Scholar]
- Mope L., McClellan G. B., Winegrad S. Calcium sensitivity of the contractile system and phosphorylation of troponin in hyperpermeable cardiac cells. J Gen Physiol. 1980 Mar;75(3):271–282. doi: 10.1085/jgp.75.3.271. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Nishizuka Y. The role of protein kinase C in cell surface signal transduction and tumour promotion. Nature. 1984 Apr 19;308(5961):693–698. doi: 10.1038/308693a0. [DOI] [PubMed] [Google Scholar]
- Noland T. A., Jr, Kuo J. F. Protein kinase C phosphorylation of cardiac troponin I or troponin T inhibits Ca2(+)-stimulated actomyosin MgATPase activity. J Biol Chem. 1991 Mar 15;266(8):4974–4978. [PubMed] [Google Scholar]
- Paul K., Ball N. A., Dorn G. W., 2nd, Walsh R. A. Left ventricular stretch stimulates angiotensin II--mediated phosphatidylinositol hydrolysis and protein kinase C epsilon isoform translocation in adult guinea pig hearts. Circ Res. 1997 Nov;81(5):643–650. doi: 10.1161/01.res.81.5.643. [DOI] [PubMed] [Google Scholar]
- Rapundalo S. T., Solaro R. J., Kranias E. G. Inotropic responses to isoproterenol and phosphodiesterase inhibitors in intact guinea pig hearts: comparison of cyclic AMP levels and phosphorylation of sarcoplasmic reticulum and myofibrillar proteins. Circ Res. 1989 Jan;64(1):104–111. doi: 10.1161/01.res.64.1.104. [DOI] [PubMed] [Google Scholar]
- Tobacman L. S., Lee R. Isolation and functional comparison of bovine cardiac troponin T isoforms. J Biol Chem. 1987 Mar 25;262(9):4059–4064. [PubMed] [Google Scholar]
- Wagoner L. E., Walsh R. A. The cellular pathophysiology of progression to heart failure. Curr Opin Cardiol. 1996 May;11(3):237–244. doi: 10.1097/00001573-199605000-00003. [DOI] [PubMed] [Google Scholar]
- Wakasaki H., Koya D., Schoen F. J., Jirousek M. R., Ways D. K., Hoit B. D., Walsh R. A., King G. L. Targeted overexpression of protein kinase C beta2 isoform in myocardium causes cardiomyopathy. Proc Natl Acad Sci U S A. 1997 Aug 19;94(17):9320–9325. doi: 10.1073/pnas.94.17.9320. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Wolff M. R., Buck S. H., Stoker S. W., Greaser M. L., Mentzer R. M. Myofibrillar calcium sensitivity of isometric tension is increased in human dilated cardiomyopathies: role of altered beta-adrenergically mediated protein phosphorylation. J Clin Invest. 1996 Jul 1;98(1):167–176. doi: 10.1172/JCI118762. [DOI] [PMC free article] [PubMed] [Google Scholar]