This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Request Permissions Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Shizukuda, Y. Articles by Ware, J. A. Search for Related Content PubMed PubMed Citation Articles by Shizukuda, Y. Articles by Ware, J. A. Related Collections Apoptosis Endothelium/vascular type/nitric oxide

(Circulation. 1999;100:1909-1916.)
© 1999 American Heart Association, Inc.

Basic Science Reports

Downregulation of Protein Kinase C Activity Enhances Endothelial Cell Adaptation to Hypoxia

Yukitaka Shizukuda, MD, PhD; Armin Helisch, MD; Ryoji Yokota, MD, PhD; J. Anthony Ware, MD

From the Cardiovascular Division, Department of Medicine, and the Department of Molecular Pharmacology, Albert Einstein College of Medicine/Montefiore Medical Center, Bronx, NY.

Background—Although protein kinase C (PKC) has been implicated in ischemic cell death, the role of individual PKC isoenzymes in the response of endothelial cells (ECs) to hypoxia is unknown.

Methods and Results—To test the effect of hypoxia on the activity of individual PKC isoenzymes, human ECs were exposed to 95% N₂ with 5% CO₂ for 24 hours. This severe hypoxia reduced PKC specific activity in both human umbilical vein ECs (HUVECs) and a HUVEC-derived EC line (ECVs) significantly (80.5±5.7% and 55.5±8.6% of normoxia controls, respectively); the activities of PKC and PKC were unchanged. The protein levels of PKC, PKC, and PKC were unchanged by hypoxia. To determine whether PKC downregulation by hypoxia was linked to EC function, ECVs in which PKC was stably overexpressed (PKC-ECs) were exposed to hypoxia. A significant increase in cell death was observed in PKC-ECs compared with controls (5.8±0.6% versus 2.3±0.4% at 24 hours, 13.2±1.2% versus 4.1±0.4% at 48 hours, P<0.05) during hypoxia. Neither the DNA laddering assay nor TUNEL staining revealed an increase in apoptosis of PKC-ECs exposed to hypoxia, suggesting a hypoxia-induced increase in nonapoptotic cell death of PKC-ECs. Inhibition of NO synthase with N^G-monomethyl-L-arginine (L-NMMA) affected neither the decline in PKC activity nor the EC death induced by hypoxia.

Conclusions—PKC activity is decreased by hypoxia by a mechanism that does not involve NO synthase; this downregulation appears to enhance EC survival during hypoxia by decreasing nonapoptotic cell death.

Key Words: endothelium • hypoxia • cell death • apoptosis • protein kinase C

This article has been cited by other articles:

				A. Siflinger-Birnboim and A. Johnson Protein kinase C modulates pulmonary endothelial permeability: a paradigm for acute lung injury Am J Physiol Lung Cell Mol Physiol, March 1, 2003; 284(3): L435 - L451. [Abstract] [Full Text] [PDF]

				A. Wang, M. Nomura, S. Patan, and J. A. Ware Inhibition of Protein Kinase C{alpha} Prevents Endothelial Cell Migration and Vascular Tube Formation In Vitro and Myocardial Neovascularization In Vivo Circ. Res., March 22, 2002; 90(5): 609 - 616. [Abstract] [Full Text] [PDF]

				Y. Shizukuda and P. M. Buttrick Protein kinase C-zeta modulates thromboxane A2-mediated apoptosis in adult ventricular myocytes via Akt Am J Physiol Heart Circ Physiol, January 1, 2002; 282(1): H320 - H327. [Abstract] [Full Text] [PDF]

				A. Rahman, K. N. Anwar, S. Uddin, N. Xu, R. D. Ye, L. C. Platanias, and A. B. Malik Protein Kinase C-{delta} Regulates Thrombin-Induced ICAM-1 Gene Expression in Endothelial Cells via Activation of p38 Mitogen-Activated Protein Kinase Mol. Cell. Biol., August 15, 2001; 21(16): 5554 - 5565. [Abstract] [Full Text] [PDF]

				Y. Shizukuda, M. E. Reyland, and P. M. Buttrick Protein kinase C-delta modulates apoptosis induced by hyperglycemia in adult ventricular myocytes Am J Physiol Heart Circ Physiol, May 1, 2002; 282(5): H1625 - H1634. [Abstract] [Full Text] [PDF]

				A. Wang, M. Nomura, S. Patan, and J. A. Ware Inhibition of Protein Kinase C{alpha} Prevents Endothelial Cell Migration and Vascular Tube Formation In Vitro and Myocardial Neovascularization In Vivo Circ. Res., March 22, 2002; 90(5): 609 - 616. [Abstract] [Full Text] [PDF]