Cardiovascular Research Advance Access first published online on April 25, 2008
This version [Corrected Proof] published online on May 17, 2008
Cardiovascular Research, doi:10.1093/cvr/cvn106
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
Overexpression of human truncated peroxisome proliferator-activated receptor
induces apoptosis in HL-1 cardiomyocytes
1 Division of Cardiovascular Sciences, Centre for Applied Medical Research, University of Navarra, CIMA, Avda. Pío XII 55, 31008 Pamplona, Spain
2 Department of Cardiology and Cardiovascular Surgery, University Clinic, School of Medicine, University of Navarra, Pamplona, Spain
* Corresponding author. Tel: +34 948 194700 (ext. 3000); fax: +34 948 194716. E-mail address: jadimar{at}unav.es
Aims: Our goal was to analyse whether truncated peroxisome proliferator-activated receptor
(PPAR
) overexpression induces apoptosis of cardiomyocytes.
Methods and results: We constructed a recombinant vector of human truncated PPAR
and a mammalian expression vector to transfect PPAR
into a line of murine cardiomyocytes designated HL-1. Four hallmarks of apoptosis were measured in these transfected cells: depolarization of mitochondrial membrane, activation of caspase-3, phosphatidylserine (PS) externalization, and DNA fragmentation. Co-transfection with human cyclic adenosine monophosphate response element-binding protein (CREB) and human CREB binding protein (CBP) and analysis of apoptosis regulatory proteins, Bcl-2 and Bax, were also performed in truncated PPAR
-transfected cells to determine the potential mechanisms by which truncated PPAR
may influence apoptosis. Progressive depolarization of mitochondrial membrane, activation of caspase-3, PS externalization, DNA fragmentation, and cell death were observed in HL-1 cells upon increasing levels of transfected truncated PPAR
. The expression of the antiapoptotic protein Bcl-2 decreased in transfected HL-1 cardiomyocytes, whereas no changes in the proapoptotic protein Bax were observed in these cells. Overexpression of CREB plus CBP abolished the inhibitory effect of truncated PPAR
on Bcl-2 protein.
Conclusion: These results demonstrate that human truncated PPAR
overexpression induces apoptosis in HL-1 cardiomyocytes. In addition, our findings suggest that truncated PPAR
may induce cardiomyocyte apoptosis through the inhibition of the antiapoptotic protein, Bcl-2. It is proposed that competition with CREB for coactivators like CBP could be involved in this inhibitory effect.
KEYWORDS Truncated PPAR
; Apoptosis; Cardiomyocytes
Time for primary review: 30 days