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Changing the cardiac calcium transient: SERCA2 overexpression versus phospholamban inhibition

  • W. H. Dillmann

Summary

Congestive heart failure is a significant medical problem, and abnormalities in calcium handling leading to a delayed decline in the calcium transient have been identified in failing hearts. Calcium lowering during diastole in cardiac myocytes is markedly influenced by the activity of the calcium ATPase of the sarcoplasmic reticulum which pumps 2 moles of calcium per mole of ATP split from the cytosol into the vesicle of the sarcoplasmic reticulum. In patients with end-stage heart failure, decreases in the level of the SERCA pump have been identified in some reports, however, have not been found by other investigators. To determine if the SERCA2 pump could be overexpressed in the hearts of transgenic mice and what contractile alterations would result, such mice were constructed. No detrimental effects were identified in those animals and a 20% increase in SERCA pump protein lead to an increase in contractile behavior under in vivo conditions and to an accelerated calcium transient and contraction in isolated myocytes under not hemodynamically loaded conditions. Compensatory functions for a hypothyroidism-induced decrease in SERCA pump activity were identified in transgenic SERCA mice. The SERCA2 transgene lead to a functional improvement by compensating for the prolonged relaxation of papillary muscle identified in wild-type hypothyroid mice. Similarly, a compensatory effect could be identified using adenoviral vectors expressing a SERCA transgene upon infection of cardiac myocytes exposed to the phorbol ester PMA which leads to a decrease in endogenous SERCA levels. In addition to improving the calcium transient by increasing the expression of SERCA2 protein levels, diminishing the inhibitory effects of phospholamban should also lead to increased SERCA activity and corresponding improvements in calcium handling and in contractile function. To explore this in further detail a dominant negative mutant of phospholamban was constructed by changing the lysine of position 3 to glutamic acid and the arginine of position 14 to glutamic acid. Adenoviral vectors expressing antisense RNA to phospholamban were also used. Infecting neonatal and adult cardiac myocytes with dominant negative mutants of phospholamban or phospholamban antisense constructs lead to a significant increase in SERCA activity, acceleration of the calcium transient, and increased myo-cyte contractility. The decreased calcium transient occurring in end-stage congestive heart failure may therefore be improved in the future using viral vector-based increases in SERCA transgene expression or in increasing SERCA activity by using phospholamban mutants or antisense constructs.

Keywords

Cardiac Myocytes Calcium Transient Dominant Negative Mutant Calcium Handling Sarcoplasmic Reticulum Calcium 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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References

  1. 1.
    Antipenko QY, Spielman AL, Kirchberger MA (1997) Comparison of the effects of phospholamban and jasmone on the calcium pump of cardiac sarcoplasmic reticulum. J Biol Chem 272:2852–2860PubMedCrossRefGoogle Scholar
  2. 2.
    ATPase of cardiac sarcoplasmic reticulum are critical for functional association with phospholamban. J Biol Chem 269:22929–22932Google Scholar
  3. 3.
    Baker DL, Hashimoto K, Grupp IL, Ji Y, Reed T, Loukianov E, Grupp G, Bhagwhat A, Hoit B, Walsh R et al (1998) Targeted overexpression of the sarcoplasmic reticulum Ca2+ ATPase increases cardiac contractility in transgenic mouse hearts. Circulation Research 83(12):1205–1214PubMedCrossRefGoogle Scholar
  4. 4.
    Bassani RA, Bassani JW, Bers DM (1992] Mitochondrial and sarcolemmal Ca2+ transport reduce [Ca2+]i during caffeine contractures in rabbit cardiac myocytes. Journal of Physiology 453:591–608PubMedGoogle Scholar
  5. 5.
    Bers DM, Berlin JR (1995) Kinetics of [Ca]i decline in cardiac myocytes depend on peak [Ca]i. American Journal of Physiology 268 (Pt 1):C271–C277PubMedGoogle Scholar
  6. 6.
    Bluhm WF, Meyer M, Sayen MR, Swanson EA, Dillmann WH (1999) Overexpression of sarcoplasmic reticulum Ca2+ -ATPase improves cardiac contractile function in hypothyroid mice. Cardiovascular Research 43:382–388PubMedCrossRefGoogle Scholar
  7. 7.
    Carafoli E (1987) Intracellular calcium homeostasis. Annu Rev Biochem 56:395–433PubMedCrossRefGoogle Scholar
  8. 8.
    Chu G, Dorn GW, Luo W, Harrer M, Kadambi VJ, Walsh RA, Kranias EG (1997) Monomeric phospholamban overexpression in transgenic mouse hearts. Circ Res 91:485–492CrossRefGoogle Scholar
  9. 9.
    Giordano FJ, He H, McDonough P, Meyer M, Sayen MR, Dillmann WH (1997) Adenovirus-mediated gene transfer reconstitutes depressed sarcoplasmic reticulum Ca2+ ATPase levels and shortens prolonged cardiac myocyte Ca2+ transients. Circulation 96:400–403PubMedCrossRefGoogle Scholar
  10. 10.
    Gwathmey JK, Copolas L, MacKinnon R, Schoen FJ, Feldman MD, Grossman W, Morgan JP (1987) Abnormal intracellular calcium handling in myocardium from patients with end-stage heart failure. Circ Res 61:70–76PubMedCrossRefGoogle Scholar
  11. 11.
    He H, Giordano FJ, Hilal-Dandan R, Rockman HA, McDonough PM, Sayen MR, Swanson E, Dillmann WH (1997) Overexpression of the rat sarcoplasmic reticulum (SR) Ca2+ ATPase gene in the heart of transgenic mice accelerates calcium transients and cardiac relaxation. J Clin Invest 100:380–389PubMedCrossRefGoogle Scholar
  12. 12.
    He H, Meyer M, Martin JL, McDonough PM, Ho P, Xiaojing L, Wilbur YW, HilalDandan R, Dillmann WH (1999) Effects of mutant and antisense RNA of phospholamban on SR Ca2+-ATPase activity and cardiac myocyte contractility. Circulation 100:974–980PubMedCrossRefGoogle Scholar
  13. 13.
    Ho PD, Zechner DK, He H, Dillmann WH, Glembotski CG, McDonough PM (1998) The Raf-MEK-ERK cascade represents a common pathway for alteration of intracellular calcium by ras and protein kinase C in cardiac myocytes. Journal of Biological Chemistry 273(34):21730–21735PubMedCrossRefGoogle Scholar
  14. 14.
    Kimura Y, Kurzydlowski K, Tada M, MacLennan DH (1997) Phospholamban inhibitory function is activated by depolymerization. J Biol Chem 272:15061–15064PubMedCrossRefGoogle Scholar
  15. 15.
    Lenfant C (1994) Report of the task force on research in heart failure. Circulation 90:1118–1123PubMedCrossRefGoogle Scholar
  16. 16.
    Luo W, Grupp IL, Harrer J, Ponniah S, Grupp G, Duffy JJ, Doetschman T, Kranias EG (1994) Targeted ablation of the phospholamban gene is associated with markedly enhanced myocardial contractility and loss of β-agonist stimulation. Circ Res 75:401–409PubMedCrossRefGoogle Scholar
  17. 17.
    Mestril R, Giordano FJ, Conde AG, Dillmann WH (1996) Adenovirus-mediated gene transfer of a heat shock protein 70 (hsp 70i) protects against simulated ischemia. Journal of Molecular and Cellular Cardiology 28(12):2351–2358PubMedCrossRefGoogle Scholar
  18. 18.
    Meyer M, Schillinger W, Pieske B, Holubarsch C, Heilmann C, Posival H, Kuwajima G, Mikoshiba K, Just H, Hasenfuß G (1995) Alterations of sarcoplasmic reticulum proteins in failing human dilated cardiomyopathy. Circulation 92:778–784PubMedCrossRefGoogle Scholar
  19. 19.
    Movsesian MA, Karimi M, Green K, Jones LR (1994) Ca2+-transporting ATPase, phospholamban, and calsequestrin levels in nonfailing and failing human myocardium. Circulation 90:653–657PubMedCrossRefGoogle Scholar
  20. 20.
    Tian R, Shen W, Dillmann WH, Ingwall JS (1998) Enhanced lusitrophy with unaltered energetics in mouse hearts overexpressing SERCA2. Circulation (Suppl) 98(17):727 (abstract)Google Scholar
  21. 21.
    Yao A, Su Z, Dillmann WH, Barry WH (1998) Sarcoplasmic reticulum function in murine ventricular myocytes overexpressing SR CaATPase. Journal of Molecular and Cellular Cardiology 30(12):2711–2718PubMedCrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2000

Authors and Affiliations

  • W. H. Dillmann
    • 1
  1. 1.University of CaliforniaSan DiegoUSA

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