Characterization of a novel c-Jun N-terminal Kinase (JNK) inhibitory peptide.
Summary of "Characterization of a novel c-Jun N-terminal Kinase (JNK) inhibitory peptide."
An improved understanding of the roles of protein kinases in intracellular signaling and disease progression has driven significant advances in protein kinase inhibitor discovery. Peptide inhibitors that target the kinase protein substrate-binding site have continued to attract attention. Here, we describe a novel c-Jun N-terminal Kinase (JNK) inhibitory peptide, PYC71N, which inhibits JNK activity in vitro towards a range of recombinant protein substrates including the transcription factors c-Jun, ATF2, Elk1 and the microtubule regulatory protein DCX. Analysis in cell culture studies confirmed the actions of a cell-permeable version of PYC71 to inhibit c-Jun phosphorylation during acute hyperosmotic stress. The analysis of the in vitro data for the kinetics of this inhibition indicated a substrate-inhibitor complex-mediated inhibition of JNK by PYC71N. Alanine scanning replacement studies revealed the importance of two residues (PYC71N Phe-9 or Phe-11 within an F-X-F motif) for JNK inhibition. The importance of these residues was confirmed through interaction studies showing that each change decreased interaction of the peptide with c-Jun. Furthermore, PYC71N interacted with both non-phosphorylated (inactive) JNK1 and the substrate, c-Jun, but did not recognize active JNK1. In contrast, a previously characterized JNK inhibitory peptide, truncated inhibitory region of JIP (TIJIP), showed stronger interaction with active JNK1. Competition binding analysis confirmed that PYC71N inhibited the interaction of c-Jun with JNK1. Taken together, our results define novel properties of the PYC71N peptide as well as differences from the characterized TIJIP, and highlight the value of these peptides to probe the biochemistry of JNK-mediated substrate interactions and phosphorylation.
Affiliation
Journal Details
This article was published in the following journal.
Name: The Biochemical journal
ISSN: 1470-8728
Pages:
Links
- PubMed Source: http://www.ncbi.nlm.nih.gov/pubmed/21162712
- DOI: http://dx.doi.org/10.1042/BJ20101244
Medical and Biotech [MESH] Definitions
Receptor, Par-2
A G-protein-coupled, proteinase-activated receptor that is expressed in a variety of tissues including ENDOTHELIUM; LEUKOCYTES; and the GASTROINTESTINAL TRACT. The receptor is activated by TRYPSIN, which cleaves off the N-terminal peptide from the receptor. The new N-terminal peptide is a cryptic ligand for the receptor. The uncleaved receptor can also be activated by the N-terminal peptide present on the activated THROMBIN RECEPTOR and by small synthetic peptides that contain the unmasked N-terminal sequence.
C-peptide
The middle segment of proinsulin that is between the N-terminal B-chain and the C-terminal A-chain. It is a pancreatic peptide of about 31 residues, depending on the species. Upon proteolytic cleavage of proinsulin, equimolar INSULIN and C-peptide are released. C-peptide immunoassay has been used to assess pancreatic beta cell function in diabetic patients with circulating insulin antibodies or exogenous insulin. Half-life of C-peptide is 30 min, almost 8 times that of insulin.
Peptide Phi
A 27-amino acid peptide with histidine at the N-terminal and isoleucine amide at the C-terminal. The exact amino acid composition of the peptide is species dependent. The peptide is secreted in the intestine, but is found in the nervous system, many organs, and in the majority of peripheral tissues. It has a wide range of biological actions, affecting the cardiovascular, gastrointestinal, respiratory, and central nervous systems.
Receptors, Thrombin
A family of proteinase-activated receptors that are specific for THROMBIN. They are found primarily on PLATELETS and on ENDOTHELIAL CELLS. Activation of thrombin receptors occurs through the proteolytic action of THROMBIN, which cleaves the N-terminal peptide from the receptor to reveal a new N-terminal peptide that is a cryptic ligand for the receptor. The receptors signal through HETEROTRIMERIC GTP-BINDING PROTEINS. Small synthetic peptides that contain the unmasked N-terminal peptide sequence can also activate the receptor in the absence of proteolytic activity.
Glicentin
A 69-amino acid peptide derived from the N-terminal of PROGLUCAGON. It is mainly produced by the INTESTINAL L CELLS. Further processing of glicentin yield a 30-amino acid N-terminal peptide (glicentin-related polypeptide) and a 37-amino acid peptide OXYNTOMODULIN. Both glicentin and oxyntomodulin can reduce digestive secretions and delay gastric emptying.
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