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Highly specific, membrane-permeant peptide blockers of cGMP-dependent protein kinase Iα inhibit NO-induced cerebral dilation

Department of Pharmacology, Department of Molecular Physiology and Biophysics, University of Vermont, College of Medicine, Burlington, VT 05405-0068, USA.
Proceedings of the National Academy of Sciences (Impact Factor: 9.81). 01/2001; 97(26):14772-7. DOI: 10.1073/pnas.97.26.14772
Source: PubMed

ABSTRACT Arrays of octameric peptide libraries on cellulose paper were screened by using (32)P-autophosphorylated cGMP-dependent protein kinase Ialpha (cGPK) to identify peptide sequences with high binding affinity for cGPK. Iterative deconvolution of every amino acid position in the peptides identified the sequence LRK(5)H (W45) as having the highest binding affinity. Binding of W45 to cGPK resulted in selective inhibition of the kinase with K(i) values of 0.8 microM and 560 microM for cGPK and cAMP-dependent protein kinase (cAPK), respectively. Fusion of W45 to membrane translocation signals from HIV-1 tat protein (YGRKKRRQRRRPP-LRK(5)H, DT-2) or Drosophila Antennapedia homeo-domain (RQIKIWFQNRRMKWKK-LRK(5)H, DT-3) proved to be an efficient method for intracellular delivery of these highly charged peptides. Rapid translocation of the peptides into intact cerebral arteries was demonstrated by using fluorescein-labeled DT-2 and DT-3. The inhibitory potency of the fusion peptides was even greater than that for W45, with K(i) values of 12.5 nM and 25 nM for DT-2 and DT-3, respectively. Both peptides were still poor inhibitors of cAPK. Selective inhibition of cGPK by DT-2 or DT-3 in the presence of cAPK was demonstrated in vitro. In pressurized cerebral arteries, DT-2 and DT-3 substantially decreased NO-induced dilation. This study provides functional characterization of a class of selective cGPK inhibitor peptides in vascular smooth muscle and reveals a central role for cGPK in the modulation of vascular contractility.

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    • "Recently, peptide inhibitors that are highly selective for PKG-I have been discovered using a phage display library approach (Dostmann et al., 2000). DT-2 and DT-3 are 1000-fold more selective for PKG vs. PKA and exhibit a 100-fold selectivity for PKG-I vs. PKG-II (Dostmann et al., 2000). These inhibitors, thus, represent useful pharmacological tools when the need to determine the contribution of PKG-I in a biological response arises. "
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