1. A retroviral-derived peptide phosphorylates protein kinase D/protein kinase Cmu involving phospholipase C and protein kinase C.
- Author
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Luangwedchakarn V, Day NK, Hitchcock R, Brown PG, Lerner DL, Rucker RP, Cianciolo GJ, Good RA, and Haraguchi S
- Subjects
- Arginine physiology, Cell Line, Tumor, Diglycerides analysis, Dose-Response Relationship, Drug, Genetic Vectors, Humans, Intercellular Signaling Peptides and Proteins, Jurkat Cells, Phosphorylation, Retroviridae genetics, Signal Transduction, T-Lymphocytes drug effects, T-Lymphocytes metabolism, Time Factors, Peptides pharmacology, Protein Kinase C metabolism, T-Lymphocytes enzymology, Viral Envelope Proteins pharmacology
- Abstract
CKS-17, a synthetic peptide representing a unique amino acid motif which is highly conserved in retroviral transmembrane proteins and other immunoregulatory proteins, induces selective immunomodulatory functions, both in vitro and in vivo, and activates intracellular signaling molecules such as cAMP and extracellular signal-regulated kinases. In the present study, using Jurkat T-cells, we report that CKS-17 phosphorylates protein kinase D (PKD)/protein kinase C (PKC) mu. Total cell extracts from CKS-17-stimulated Jurkat cells were immunoblotted with an anti-phospho-PKCmu antibody. The results show that CKS-17 significantly phosphorylates PKD/PKCmu in a dose- and time-dependent manner. Treatment of cells with the PKC inhibitors GF 109203X and Ro 31-8220, which do not act directly on PKD/PKCmu, attenuates CKS-17-induced phosphorylation of PKD/PKCmu. In contrast, the selective protein kinase A inhibitor H-89 does not reverse the action of CKS-17. Furthermore, a phospholipase C (PLC) selective inhibitor, U-73122, completely blocks the phosphorylation of PKD/PKCmu by CKS-17 while a negative control U-73343 does not. In addition, substitution of lysine for arginine residues in the CKS-17 sequence completely abrogates the ability of CKS-17 to phosphorylate PKD/PKCmu. These results clearly indicate that CKS-17 phosphorylates PKD/PKCmu through a PLC- and PKC-dependent mechanism and that arginine residues play an essential role in this activity of CKS-17, presenting a novel modality of the retroviral peptide CKS-17 and molecular interaction of this compound with target cells.
- Published
- 2003
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