© 1999 by European Society of Cardiology
Copyright © 1999, European Society of Cardiology
Overexpression of long or short FGFR-1 results in FGF-2-mediated proliferation in neonatal cardiac myocyte cultures
aDepartment of Human Anatomy and Cell Sciences, Institute of Cardiovascular Sciences, St. Boniface Hospital Research Centre, 351 Tache Avenue, Winnipeg, Manitoba, Canada R2H 2A6
bDepartment of Physiology, University of Manitoba, 730 William Avenue, Winnipeg, Manitoba, Canada R3E 3J7
Peter_Cattini{at}UManitoba.CA
* Corresponding author. Tel.: +204-789-3735; fax: +204-789-3734
Objective: The type 1 fibroblast growth factor receptor (FGFR-1) is the only high affinity receptor for fibroblast growth factor-2 (FGF-2) in the rat myocardium, and is essential for normal growth and development of the heart. Levels of FGFR-1 are developmentally regulated, being high in embryonic cardiac myocytes. Also, FGFR-1 exists as both ‘long’ and ‘short’ isoforms, and there is a switch from predominant expression of the ‘long’ isoform in the embryo to the ‘short’ isoform in the adult heart. Both the decrease in receptor levels and the isoform switch in postnatal cardiac myocytes correlate with a loss of proliferative potential. We investigated whether an increase in either ‘long’ or ‘short’ FGFR-1 isoforms could stimulate proliferation in postnatal rat cardiac myocyte cultures. Methods and Results: Previously we cloned cDNAs corresponding to ‘long’ (L) and ‘short’ (S) FGFR-1 isoforms from embryonic mouse hearts. Hybrid FGFR-1(L) and (S) genes, directed by a myosin light chain-2 promoter and SV40 enhancer sequences, were generated and used to transiently transfect neonatal rat cardiac myocytes. Overexpression of FGFR-1 mRNA and protein was detected by RNA blotting and immunocytochemistry. Ligand-crosslinking confirmed the presence of specific receptors capable of binding FGF-2 on the cell membrane. Overexpression of either FGFR-1(L) or (S) was associated with stimulation of proliferation as assessed by significant increases in bromodeoxyuridine uptake (DNA synthesis) and cell number. To determine whether this response was FGF-2 specific, the level of FGF-2 was assessed in the culture medium of cardiac myocytes overexpressing FGFR-1 isoforms. A three-fold increase was detected in the media of cardiac myocytes overexpressing either FGFR-1(L) or (S) compared to control levels. Neutralization of this FGF-2 with antibodies inhibited the proliferative response. Conclusion: Overexpression of either FGFR-1(L) or (S) resulted in an increase in FGF-2-mediated proliferation of postnatal rat cardiac myocytes.
KEYWORDS Myocyte; Growth factors; Receptors; Gene expression; Cell culture/isolation
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  S. Y. Lu, D. P. Sontag, K. A. Detillieux, and P. A. Cattini FGF-16 is released from neonatal cardiac myocytes and alters growth-related signaling: a possible role in postnatal development Am J Physiol Cell Physiol, May 1, 2008; 294(5): C1242 - C1249. [Abstract] [Full Text] [PDF]
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