PR39 inhibits apoptosis in hypoxic endothelial cells: role of inhibitor apoptosis protein-2.
BACKGROUND
PR39 is a proline- and arginine-rich peptide implicated in wound healing and myocardial ischemia protection. To determine the potential mechanisms of PR39 in ischemia, we examined the role of PR39 in hypoxia-induced apoptosis in vascular endothelial cells.


RESULTS
Hypoxia results in an increase of apoptosis in bovine aortic endothelial cells (BAECs), as determined by terminal deoxynucleotidyl transferase-mediated dUTP biotin nick-end labeling (TUNEL) analysis and caspase-3 activity. Hypoxia induced 66.2+/-2.7% TUNEL-positive cells, whereas in the presence of synthesized PR39 peptide, TUNEL-positive cells were reduced to 29.6+/-1.9% (P<0.05). After 24 hours of hypoxia, the addition of PR39 reduced caspase-3 activity to 3.17+/-0.47 pMol/min from 10.52+/-0.55 pMol/min in hypoxic BAECs. Moreover, PR39 increased inhibitor of apoptosis protein-2 (IAP-2) gene and protein expression by 3-fold in a time- and dose-dependent manner. The induction of IAP-2 by PR39 conferred an increase in IAP-2 gene transcription and IAP-2 mRNA stability. Furthermore, inhibiting IAP-2 with second mitochondria-derived activator of caspase (Smac) and with small interfering RNA targeting IAP-2 abrogated the ability of PR39 to reduce caspase-3 activity.


CONCLUSIONS
We provide the first direct evidence for PR39 as an antiapoptotic factor in endothelial cells during hypoxia. These data suggest that PR39 inhibits hypoxia-induced apoptosis and decreases caspase-3 activity in endothelial cells through an increase of IAP-2 expression.
Wu
Jiaping
J
Angiogenesis Research Center, Division of Cardiology, Beth Israel Deaconess Medical Center, Harvard Medical School, Boston, Mass 02215, USA.
Parungo
Cherie
C
Wu
Guifu
G
Kang
Peter M
PM
Laham
Roger J
RJ
Sellke
Frank W
FW
Simons
Michael
M
Li
Jian
J
D000595:Amino Acid Sequence; D000818:Animals; D023181:Antimicrobial Cationic Peptides / Q000494:pharmacology* / Q000502:physiology; D017209:Apoptosis / Q000187:drug effects*; D051017:Apoptosis Regulatory Proteins; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology; D053148:Caspase 3; D061945:Caspase Inhibitors; D020169:Caspases / Q000502:physiology; D002417:Cattle; D015687:Cell Hypoxia; D004305:Dose-Response Relationship, Drug; D042783:Endothelial Cells / Q000166:cytology / Q000187:drug effects*; D004730:Endothelium, Vascular / Q000166:cytology*; D004789:Enzyme Activation / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects; D006801:Humans; D020287:In Situ Nick-End Labeling; D051034:Inhibitor of Apoptosis Proteins; D047908:Intracellular Signaling Peptides and Proteins; D024101:Mitochondrial Proteins / Q000235:genetics / Q000502:physiology; D008969:Molecular Sequence Data; D014176:Protein Biosynthesis; D011506:Proteins / Q000235:genetics / Q000502:physiology; D034741:RNA, Small Interfering / Q000235:genetics; D014162:Transfection
D023181:Antimicrobial Cationic Peptides; D051017:Apoptosis Regulatory Proteins; D002352:Carrier Proteins; D061945:Caspase Inhibitors; C412403:DIABLO protein, human; D051034:Inhibitor of Apoptosis Proteins; D047908:Intracellular Signaling Peptides and Proteins; D024101:Mitochondrial Proteins; D011506:Proteins; D034741:RNA, Small Interfering; C072212:PR 39; C505407:CASP3 protein, human; D053148:Caspase 3; D020169:Caspases