title: A retroviral-derived peptide phosphorylates protein kinase D/protein kinase Cmu involving phospholipase C and protein kinase C.
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.
authors.affiliation: Division of Allergy and Immunology, Department of Pediatrics, University of South Florida, All Children's Hospital, St. Petersburg, FL 33701, USA.
authors.forename: Voravich
authors.initials: V
authors.lastname: Luangwedchakarn
authors.forename: Noorbibi K
authors.initials: NK
authors.lastname: Day
authors.forename: Remi
authors.initials: R
authors.lastname: Hitchcock
authors.forename: Pam G
authors.initials: PG
authors.lastname: Brown
authors.forename: Danica L
authors.initials: DL
authors.lastname: Lerner
authors.forename: Rajivi P
authors.initials: RP
authors.lastname: Rucker
authors.forename: George J
authors.initials: GJ
authors.lastname: Cianciolo
authors.forename: Robert A
authors.initials: RA
authors.lastname: Good
authors.forename: Soichi
authors.initials: S
authors.lastname: Haraguchi
mesh_terms: D001120:Arginine / Q000502:physiology; D045744:Cell Line, Tumor; D004075:Diglycerides / Q000032:analysis; D004305:Dose-Response Relationship, Drug; D005822:Genetic Vectors; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins; D019169:Jurkat Cells; D010455:Peptides / Q000494:pharmacology*; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism*; D012190:Retroviridae / Q000235:genetics; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism; D013997:Time Factors; D014759:Viral Envelope Proteins / Q000494:pharmacology*
chemical_list: D004075:Diglycerides; D036341:Intercellular Signaling Peptides and Proteins; D010455:Peptides; D014759:Viral Envelope Proteins; D001120:Arginine; C053692:CKS 17; C089212:protein kinase D; D011493:Protein Kinase C