Requirement for protein kinase C in reactive oxygen species-induced apoptosis of vascular smooth muscle cells.
BACKGROUND
Vascular smooth muscle cell (VSMC) apoptosis is a component of a variety of cardiovascular diseases and may be related to reactive oxygen species (ROS). This study was designed to determine the role of protein kinase C (PKC) in ROS-induced VSMC apoptosis.


RESULTS
Rat aortic VSMCs were exposed to H(2)O(2), and the nature of cell death was characterized in the absence or presence of different PKC inhibitors. The results demonstrate that exposure of VSMCs to H(2)O(2) led to a dose-dependent (25 to 100 micromol/L) and time-dependent (peak at 2 minutes) activation of PKC. Among the PKC isoforms alpha, beta, delta, epsilon, and zeta, only PKC-alpha and PKC-epsilon were found to change their intracellular distribution on H(2)O(2) treatment. Apoptosis was the predominant form of cell death when PKC had been activated by H(2)O(2) alone or by H(2)O(2) in the presence of 50 nmol/L phorbol 12-myristate 13-acetate. In contrast, necrosis became the predominant form of cell death when PKC had been downregulated by prolonged exposure to 200 nmol/L phorbol 12,13-dibutyrate or inhibited by 50 nmol/L staurosporine, 100 nmol/L calphostin C, or 30 micromol/L H-7. In addition, caspase-3 was activated in H(2)O(2)-induced VSMC apoptosis but not when PKC was downregulated or inhibited. Inhibition of caspase-3 by 50 micromol/L Ac-DEVD-CHO could significantly attenuate H(2)O(2)-induced apoptosis and was not associated with the induction of necrosis.


CONCLUSIONS
We conclude that in VSMCs, PKC converts the ROS-induced signals from necrotic cell death to the activation of an apoptotic cell death program. These data imply a novel and important role of PKC for the pathogenesis of such vascular diseases as atherosclerosis, restenosis, and hypertension.
Li
P F
PF
Department of Cardiology, Franz Volhard Clinic, Humboldt University Berlin, Germany.
Maasch
C
C
Haller
H
H
Dietz
R
R
von Harsdorf
R
R
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine / Q000494:pharmacology; D000818:Animals; D017209:Apoptosis; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D004797:Enzyme-Linked Immunosorbent Assay; D005434:Flow Cytometry; D006861:Hydrogen Peroxide / Q000494:pharmacology; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D009131:Muscle, Smooth, Vascular / Q000166:cytology / Q000201:enzymology / Q000378:metabolism*; D009281:Naphthalenes / Q000494:pharmacology; D009336:Necrosis; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors* / Q000187:drug effects / Q000378:metabolism*; D051381:Rats; D017382:Reactive Oxygen Species / Q000378:metabolism*; D019311:Staurosporine / Q000494:pharmacology; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology
D004791:Enzyme Inhibitors; D009281:Naphthalenes; D017382:Reactive Oxygen Species; C061465:calphostin complex; D015240:Phorbol 12,13-Dibutyrate; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D006861:Hydrogen Peroxide; D011493:Protein Kinase C; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate