Parathyroid hormone-related protein (PTHrP)-dependent regulation of bcl-2 and tissue inhibitor of metalloproteinase (TIMP)-1 in coronary endothelial cells.
BACKGROUND
An increased susceptibility of micro-vascular endothelial cells to apoptosis is considered to be an initial event leading to atherosclerosis. Parathyroid hormone-related peptide (PTHrP) is known to protect endothelial cells against apoptosis by the regulation of the anti-apoptotic gene bcl-2. As tissue inhibitor of metalloproteinase (TIMP-1) expression is regulated by bcl-2, we hypothesized that endothelial expression of PTHrP also regulates the expression of TIMP-1.


METHODS
The steady state mRNA expressions of bcl-2, bax, TIMP-1, and TIMP-2 were analyzed by real-time RT-PCR and their protein expression by immunoblotting. The tissue distribution of PTHrP was investigated in cryosections of hearts from normotensive and hypertensive rats.


RESULTS
Phenylephrine, an alpha(1)-adrenoceptor agonist, increased the expression of PTHrP, bcl-2, and TIMP-1. Transfection of endothelial cells with oligonucleotides directed against PTHrP attenuated this effect. Antisense transfection and TGF-beta(1) (10 ng/ml) decreased the expression of PTHrP, bcl-2, TIMP-1, and TIMP-2, but not that of bax. Endothelial cells were identified as the main source of PTHrP in the heart. Endothelial cells in hearts from spontaneously hypertensive rats showed reduced staining with a PTHrP antibody compared to control normotensive hearts.


CONCLUSIONS
These data suggests that the down-regulation of PTHrP favours atherosclerosis in chronic pressure overload.
Conzelmann
Charlotte
C
Justus-Liebig-Universitat, Physiologisches Institut, Giessen, Germany.
Krasteva
Gabriela
G
Weber
Kerstin
K
Kummer
Wolfgang
W
Schluter
Klaus-Dieter
KD
D000818:Animals; D017209:Apoptosis; D002478:Cells, Cultured; D003331:Coronary Vessels / Q000166:cytology*; D015536:Down-Regulation; D042783:Endothelial Cells / Q000378:metabolism*; D004730:Endothelium, Vascular / Q000166:cytology*; D008297:Male; D044162:Parathyroid Hormone-Related Protein / Q000235:genetics / Q000378:metabolism*; D010656:Phenylephrine / Q000494:pharmacology; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000235:genetics / Q000378:metabolism*; D016372:RNA, Antisense / Q000378:metabolism; D051381:Rats; D017208:Rats, Wistar; D019715:Tissue Inhibitor of Metalloproteinase-1 / Q000235:genetics / Q000378:metabolism*; D019716:Tissue Inhibitor of Metalloproteinase-2 / Q000235:genetics / Q000378:metabolism; D053773:Transforming Growth Factor beta1 / Q000494:pharmacology; D051028:bcl-2-Associated X Protein / Q000235:genetics / Q000378:metabolism
D044162:Parathyroid Hormone-Related Protein; D019253:Proto-Oncogene Proteins c-bcl-2; D016372:RNA, Antisense; D019715:Tissue Inhibitor of Metalloproteinase-1; D053773:Transforming Growth Factor beta1; D051028:bcl-2-Associated X Protein; D019716:Tissue Inhibitor of Metalloproteinase-2; D010656:Phenylephrine