© 1996 American Heart Association, Inc.
Articles |
Fibroblast Growth Factor-2 Decreases Metabolic Coupling and Stimulates Phosphorylation as Well as Masking of Connexin43 Epitopes in Cardiac Myocytes
the St. Boniface General Hospital Research Centre (B.W.D., Y.C., E.K.), Departments of Anatomy and Physiology, and the Manitoba Institute of Cell Biology (D.G.B., D.W.L.), Faculty of Medicine, University of Manitoba, Winnipeg, Canada.
Correspondence to E. Kardami, St. Boniface General Hospital Research Centre, Division of Cardiovascular Sciences, 351 Tache Ave, Winnipeg, Manitoba, Canada R2H 2A6. E-mail ekardami@salk.sbrc.umanitoba.ca.
Cardiac gap junction (GJ) channels, composed of connexins, allow electrical and metabolic couplings between cardiomyocytes, properties important for coordinated action of the heart as well as tissue homeostasis and control of growth and differentiation. Fibroblast growth factor-2 (FGF-2) is an endogenous growth-promoting protein, believed to participate in the short- and long-term responses of the heart to injury. We have examined short-term effects of FGF-2 on cardiac myocyte GJ–mediated metabolic coupling, using cultures of neonatal rat cardiomyocytes. FGF-2 decreased coupling between cardiomyocytes assessed by scrape dye loading as well as microinjection and dye transfer within 30 minutes of administration. Genistein blocked the effects of FGF-2. To determine the mechanism, we next assessed the effect of FGF-2 on expression, distribution, and phosphorylation of connexin43 (Cx43), which is a major cardiomyocyte connexin. FGF-2 did not affect Cx43 mRNA or protein accumulation and synthesis, and it did not change Cx43 localization at sites of intercellular contact as assessed by immunostaining with a polyclonal anti-Cx43 antibody raised against a synthetic peptide containing residues 346 to 363 of Cx43. FGF-2, however, decreased staining intensity at sites of intermyocyte contact when a monoclonal anti-Cx43 antibody was used, suggesting a localized masking of epitope(s) recognized by the monoclonal but not the polyclonal antibody. These epitopes appear to reside within residues 261 to 270 of Cx43, as indicated by full quenching of monoclonal antibody staining with synthetic peptides. In addition, FGF-2 induced a more than twofold increase in Cx43 phosphorylation. Phosphoamino acid analysis indicated increased phosphorylation of Cx43 on serine residues. Although tyrosine phosphorylation of Cx43 was not detected in either treated or control cells, a fraction of Cx43 was immunoprecipitated with anti–phosphotyrosine-specific antibodies in FGF-2–treated myocytes, suggesting interaction (and hence coprecipitation) with phosphotyrosine-containing protein(s). In conclusion, we have identified Cx43 and intercellular communication as targets of FGF-2–triggered and tyrosine phosphorylation–dependent signal transduction in cardiac myocytes. It is suggested that phosphorylation of Cx43 on serine induced by FGF-2 contributes to decreased metabolic coupling between cardiomyocytes.
Key Words: fibroblast growth factor • cardiomyocyte coupling • connexin43 • phosphorylation
This article has been cited by other articles:
 |
|
 |
|
  W. Srisakuldee, M. M. Jeyaraman, B. E. Nickel, S. Tanguy, Z.-S. Jiang, and E. Kardami Phosphorylation of connexin-43 at serine 262 promotes a cardiac injury-resistant state Cardiovasc Res, September 1, 2009; 83(4): 672 - 681. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
A. Hagen, A. Dietze, and S. Dhein Human cardiac gap-junction coupling: effects of antiarrhythmic peptide AAP10 Cardiovasc Res, July 15, 2009; 83(2): 405 - 415. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
D. J. Hausenloy and D. M. Yellon Cardioprotective growth factors Cardiovasc Res, July 15, 2009; 83(2): 179 - 194. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Imamura, H. Negoro, A. Kanematsu, S. Yamamoto, Y. Kimura, K. Nagane, T. Yamasaki, I. Kanatani, N. Ito, Y. Tabata, et al. Basic fibroblast growth factor causes urinary bladder overactivity through gap junction generation in the smooth muscle Am J Physiol Renal Physiol, July 1, 2009; 297(1): F46 - F54. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 R. Lewandowski, K. Procida, R. Vaidyanathan, W. Coombs, J. Jalife, M. S. Nielsen, S. M. Taffet, and M. Delmar RXP-E: A Connexin43-Binding Peptide That Prevents Action Potential Propagation Block Circ. Res., August 29, 2008; 103(5): 519 - 526. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. F. Ek-Vitorin, T. J. King, N. S. Heyman, P. D. Lampe, and J. M. Burt Selectivity of Connexin 43 Channels Is Regulated Through Protein Kinase C-Dependent Phosphorylation Circ. Res., June 23, 2006; 98(12): 1498 - 1505. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 C. Hurtado, M. Prociuk, T. G. Maddaford, E. Dibrov, N. Mesaeli, L. V. Hryshko, and G. N. Pierce Cells expressing unique Na+/Ca2+ exchange (NCX1) splice variants exhibit different susceptibilities to Ca2+ overload Am J Physiol Heart Circ Physiol, May 1, 2006; 290(5): H2155 - H2162. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
S. Somekawa, S. Fukuhara, Y. Nakaoka, H. Fujita, Y. Saito, and N. Mochizuki Enhanced Functional Gap Junction Neoformation by Protein Kinase A-Dependent and Epac-Dependent Signals Downstream of cAMP in Cardiac Myocytes Circ. Res., September 30, 2005; 97(7): 655 - 662. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
F. Sheikh, C. J.A. Hirst, Y. Jin, M. E. Bock, R. R. Fandrich, B. E. Nickel, B. W. Doble, E. Kardami, and P. A. Cattini Inhibition of TGF{beta} signaling potentiates the FGF-2-induced stimulation of cardiomyocyte DNA synthesis Cardiovasc Res, December 1, 2004; 64(3): 516 - 525. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. Schulz and G. Heusch Connexin 43 and ischemic preconditioning Cardiovasc Res, May 1, 2004; 62(2): 335 - 344. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Z.-S. Jiang, W. Srisakuldee, F. Soulet, G. Bouche, and E. Kardami Non-angiogenic FGF-2 protects the ischemic heart from injury, in the presence or absence of reperfusion Cardiovasc Res, April 1, 2004; 62(1): 154 - 166. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B. W. Doble, X. Dang, P. Ping, R. R. Fandrich, B. E. Nickel, Y. Jin, P. A. Cattini, and E. Kardami Phosphorylation of serine 262 in the gap junction protein connexin-43 regulates DNA synthesis in cell-cell contact forming cardiomyocytes J. Cell Sci., January 22, 2004; 117(3): 507 - 514. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 J. C. SAEZ, V. M. BERTHOUD, M. C. BRANES, A. D. MARTINEZ, and E. C. BEYER Plasma Membrane Channels Formed by Connexins: Their Regulation and Functions Physiol Rev, October 1, 2003; 83(4): 1359 - 1400. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. A. Detillieux, F. Sheikh, E. Kardami, and P. A. Cattini Biological activities of fibroblast growth factor-2 in the adult myocardium Cardiovasc Res, January 1, 2003; 57(1): 8 - 19. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. A.B. van Veen, H. V.M. van Rijen, and T. Opthof Cardiac gap junction channels: modulation of expression and channel properties Cardiovasc Res, August 1, 2001; 51(2): 217 - 229. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
B. W. Doble, P. Ping, and E. Kardami The {epsilon} Subtype of Protein Kinase C Is Required for Cardiomyocyte Connexin-43 Phosphorylation Circ. Res., February 18, 2000; 86(3): 293 - 301. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
T. Toyofuku, M. Yabuki, K. Otsu, T. Kuzuya, M. Tada, and M. Hori Functional Role of c-Src in Gap Junctions of the Cardiomyopathic Heart Circ. Res., October 15, 1999; 85(8): 672 - 681. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. T. Kurjiaka, T. D. Steele, M. V. Olsen, and J. M. Burt Gap junction permeability is diminished in proliferating vascular smooth muscle cells Am J Physiol Cell Physiol, December 1, 1998; 275(6): C1674 - C1682. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 B. Nadarajah, H. Makarenkova, D. L. Becker, W. H. Evans, and J. G. Parnavelas Basic FGF Increases Communication between Cells of the Developing Neocortex J. Neurosci., October 1, 1998; 18(19): 7881 - 7890. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
N. Homma, J. L. Alvarado, W. Coombs, K. Stergiopoulos, S. M. Taffet, A. F. Lau, and M. Delmar A Particle-Receptor Model for the Insulin-Induced Closure of Connexin43 Channels Circ. Res., July 13, 1998; 83(1): 27 - 32. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. TAKAHASHI and Y. OKAMURA Ion Channels and Early Development of Neural Cells Physiol Rev, April 1, 1998; 78(2): 307 - 337. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
Z.-S. Jiang, R. R. Padua, H. Ju, B. W. Doble, Y. Jin, J. Hao, P. A. Cattini, I. M. C. Dixon, and E. Kardami Acute protection of ischemic heart by FGF-2: involvement of FGF-2 receptors and protein kinase C Am J Physiol Heart Circ Physiol, March 1, 2002; 282(3): H1071 - H1080. [Abstract] [Full Text] [PDF]
|
|