Published online before print March 15, 2007, doi: 10.1161/01.RES.0000264058.28808.cc
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Submitted on July 18, 2006
Revised on March 3, 2007
Accepted on March 7, 2007
Regulation of Cardiac cAMP Synthesis and Contractility by Nucleoside Diphosphate Kinase B/G Protein 
Dimer Complexes
Hans-Joerg Hippe *;
From the Innere Medizin III - Kardiologie (H.-J.H., M.L., H.K., N.F., H.A.K., F.N.), Universität Heidelberg, Heidelberg, Germany, 
Institut für Experimentelle und Klinische Pharmakologie und Toxikologie (S.L., T.W.), Universität Heidelberg, Mannheim, Germany, ¶Institut für Experimentelle und Klinische Pharmakologie und Toxikologie (T.E.), Universität Hamburg, Hamburg, Germany.
* To whom correspondence should be addressed. E-mail: hans-joerg.hippe{at}med.uni-heidelberg.de.
Heterotrimeric G proteins are pivotal regulators of myocardial contractility. In addition to the receptor-induced GDP/GTP exchange, G protein 
subunits can be activated by a phosphate transfer via a plasma membrane-associated complex of nucleoside diphosphate kinase B (NDPK B) and G protein 
-dimers (G). To investigate the physiological role of this phosphate transfer in cardiomyocytes, we generated a G12-dimer carrying a single amino acid exchange at the intermediately phosphorylated His-266 in the 1 subunit (G1H266L2). Recombinantly expressed G1H266L2 were integrated into heterotrimeric G proteins in rat cardiomyocytes but were deficient in intermediate G phosphorylation. Compared with wild-type G12 (G1WT2), overexpression of G1H266L2 suppressed basal cAMP formation up to 55%. A similar decrease in basal cAMP production occurred when the formation of NDPK B/G complexes was attenuated by siRNA-mediated NDPK B knockdown. In adult rat cardiomyocytes expressing G1H266L2, the basal contractility was suppressed by 
50% which correlated to similarly reduced basal cAMP levels and reduced Ser16-phosphorylation of phospholamban. In the presence of the -adrenoceptor agonist isoproterenol, the total cAMP formation and contractility were significantly lower in G1H266L2 than in G1WT2 expressing cardiomyocytes. However, the relative isoproterenol-induced increased was not affected by G1H266L2.
We conclude that the receptor-independent activation of G proteins via NDPK B/G complexes requires the intermediate phosphorylation of G protein subunits at His-266. Our results highlight the histidine kinase activity of NDPK B for G and demonstrate its contribution to the receptor-independent regulation of cAMP synthesis and contractility in intact cardiomyocytes.
Key words: G proteins • NDPK • cardiomyocytes • cAMP • contractility
Related Article:
- G Proteins: More Than Transducers of Receptor-Generated Signals?
- Stefan Engelhardt and Francesca Rochais
Circ. Res. 2007 100: 1109-1111.[Extract] [Full Text] [PDF]
This article has been cited by other articles:
 |
|
 |
|
  H.-J. Hippe, N. M. Wolf, I. Abu-Taha, R. Mehringer, S. Just, S. Lutz, F. Niroomand, E. H. Postel, H. A. Katus, W. Rottbauer, et al. The interaction of nucleoside diphosphate kinase B with G{beta}{gamma} dimers controls heterotrimeric G protein function PNAS, September 22, 2009; 106(38): 16269 - 16274. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Klumpp and J. Krieglstein Reversible Phosphorylation of Histidine Residues in Proteins from Vertebrates Sci. Signal., March 10, 2009; 2(61): pe13 - pe13. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 H. Korhonen, B. Fisslthaler, A. Moers, A. Wirth, D. Habermehl, T. Wieland, G. Schutz, N. Wettschureck, I. Fleming, and S. Offermanns Anaphylactic shock depends on endothelial Gq/G11 J. Exp. Med., February 16, 2009; 206(2): 411 - 420. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. Engelhardt and F. Rochais G Proteins: More Than Transducers of Receptor-Generated Signals? Circ. Res., April 27, 2007; 100(8): 1109 - 1111. [Full Text] [PDF]
|
|