QUICK SEARCH:   [advanced] Author: Keyword(s): Year:  Vol:  Page:

This Article Full Text Full Text (PDF) Submit a response Alert me when this article is cited Alert me when eLetters are posted Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Taylor, M. S. Articles by Dostmann, W. R. G. Search for Related Content PubMed PubMed Citation Articles by Taylor, M. S. Articles by Dostmann, W. R. G.

Inhibition of cGMP-Dependent Protein Kinase by the Cell-Permeable Peptide DT-2 Reveals a Novel Mechanism of Vasoregulation

Department of Pharmacology, University of Vermont, College of Medicine, Burlington, Vermont (M.S.T., C.O., C.K.N., J.E.B., W.R.G.D.); and German Research Centre for Biotechnology, Chemical Biology, Braunschweig, Germany (W.J.T.)

Cyclic GMP-dependent protein kinase (PKG) serves as an important physiological regulator of vascular reactivity and tone. However, available inhibitors of PKG have exhibited variable effects in intact tissue, hindering the elucidation of the functional role of PKG in blood vessels. In this study, we have determined the effects of our previously engineered potent and selective PKG I inhibitor DT-2 on basal and cGMP-stimulated purified recombinant PKG, and compared DT-2 with commonly used PKG inhibitors (8R,9S,11S)-(–)-9-methoxy-carbamyl-8-methyl-2,3,9,10-tetrahydro-8,11-epoxy-1H,8H,11H-2,7b,11a-trizadibenzo-(a,g)-cycloocta-(c,d,e)-trinden-1-one (KT-5823), Rp-8-(4-chlorophenylthio)-guanosine-3',5'-cyclic monophosphorothioate (Rp-8-pCPT-cGMPS), and (-phenyl-1,N2-etheno-8-bromoguanosine-3',5'-cyclic monophosphorothioate, Rp-isomer (Rp-8-Br-PET-cGMPS). As expected, all inhibitors reduced cGMP-stimulated PKG activity. However, only DT-2 decreased cGMP-independent or basal PKG activity, whereas KT5823 showed no effect and the Rp-compounds actually had partial agonist activity. To evaluate the potential functional impact of this unique inhibition by DT-2 under physiologically relevant conditions, we analyzed the inhibitors in isolated pressurized cerebral arteries. KT-5823 and Rp-8-pCPT-cGMPS demonstrated marginal reversal of vasodilation induced by 8-Br-cGMP. By comparison, DT-2 completely reversed 8-Br-cGMP induced dilations with comparable potency to Rp-8-Br-PET-cGMPS. In fact, DT-2 constricted arteries beyond their starting (pre-8-Br-cGMP) diameters and caused constriction even in the absence of exogenous 8-Br-cGMP, an effect that was not observed with any other inhibitor. The direct constricting effect of DT-2 was essentially abolished in cultured arteries, where PKG expression was reduced by approximately 90%. These findings indicate that DT-2 not only effectively inhibits cGMP-stimulated PKG activity but also reduces basal PKG activity both in vitro and in vivo. Moreover, these distinctive inhibitory properties of DT-2 suggest an important role for constitutive PKG activity in the continuous regulation of cerebral artery tone.

Address correspondence to: Dr. Wolfgang Dostmann, University of Vermont, Department of Pharmacology, Health Science Research Facility 330, 149 Beaumont Avenue, Burlington, VT 05405-0075. E-mail: wolfgang.dostmann{at}uvm.edu

This article has been cited by other articles:

				P. F. Bove, U. V. Wesley, A.-K. Greul, M. Hristova, W. R. Dostmann, and A. van der Vliet Nitric Oxide Promotes Airway Epithelial Wound Repair through Enhanced Activation of MMP-9 Am. J. Respir. Cell Mol. Biol., February 1, 2007; 36(2): 138 - 146. [Abstract] [Full Text] [PDF]

				E. N. Christensen and M. E. Mendelsohn Cyclic GMP-dependent Protein Kinase I{alpha} Inhibits Thrombin Receptor-mediated Calcium Mobilization in Vascular Smooth Muscle Cells J. Biol. Chem., March 31, 2006; 281(13): 8409 - 8416. [Abstract] [Full Text] [PDF]

				T. Krieg, S. Philipp, L. Cui, W. R. Dostmann, J. M. Downey, and M. V. Cohen Peptide blockers of PKG inhibit ROS generation by acetylcholine and bradykinin in cardiomyocytes but fail to block protection in the whole heart Am J Physiol Heart Circ Physiol, April 1, 2005; 288(4): H1976 - H1981. [Abstract] [Full Text] [PDF]