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Engineering a delta protein kinase C inhibitor that selectively inhibits interaction and phosphorylation of one substrate of the multi‐substrate kinase (582.3)
Author(s) -
Qvit Nir,
Disatnik MarieHelene,
MochlyRosen Daria
Publication year - 2014
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.28.1_supplement.582.3
Subject(s) - phosphorylation , protein kinase c , kinase , microbiology and biotechnology , chemistry , protein kinase a , biology
Rationale: Many kinases phosphorylate multiple substrates. To assess the role of an individual phosphorylation event without using laborious mutagenesis studies, selective pharmacological tools that inhibit phosphorylation of specific one substrate are needed. We focused on delta protein kinase C (δPKC) because δPKC activation after heart attack leads to cardiac damage. We reasoned that since pyruvate dehydrogenase kinase (PDK) phosphorylation by δPKC leads to inhibition of ATP production, it might be critical in the injurious effect δPKC after heart attack. To determine if of the many substrates of δPKC, PDK is the substrate that mediates this injurious effect in the heart, we designed a selective inhibitor of δPKC binding and phosphorylation of PDK. Methods: We designed a short peptide inhibitor that mimics a unique interaction between PDK and δPKC to selectively inhibit δPKC phosphorylation of PDK. This protein‐protein interaction inhibitory peptide (PPIIP) was used in vitro, in cells and in intact heart, in models of heart attack. Results: PDK/δPKC interaction was inhibited by PPIIP in vitro and in vivo. PDK/δPKC PPIIP selectively inhibited phosphorylation of PDK without affecting phosphorylation of several other δPKC substrates. Treatment with PDK/δPKC PPIIP inhibited myocardial infarction‐induced PDK phosphorylation without inhibiting the phosphorylation of other δPKC substrates. Further, PDK/δPKC PPIIP treatment led to a 50% reduction in infarct size, in release of cardiac enzyme (a measure of cell lysis) and in JNK phosphorylation, all markers of cardiac injury. Conclusion: PDK/δPKC PPIIP is a selective inhibitor of PDK phosphorylation by δPKC. Of the several δPKC‐mediated phosphorylation events following heart attack, δPKC‐induced PDK phosphorylation is sufficient to cause cardiac injury as a selective inhibitor of this phosphorylation event alone was sufficient to provide great reduction in δPKC‐mediated cardiac injury after heart attack.