title: Protein kinase C epsilon dependence of the recovery from down-regulation of S1P1 G protein-coupled receptors of T lymphocytes.
abstract: Sphingosine 1-phosphate (S1P) from mononuclear phagocytes and platelets signals T cells predominantly through S1P1 G protein-coupled receptors (Rs) to enhance survival, stimulate and suppress migration, and inhibit other immunologically relevant responses. Cellular S1P1 Rs and their signaling functions are rapidly down-regulated by S1P, through a protein kinase C (PKC)-independent mechanism, but characteristics of cell-surface re-expression of down-regulated S1P1 Rs have not been elucidated. T cell chemotactic responses (CT) to 10 and 100 nm S1P and inhibition of T cell chemotaxis to chemokines (CI) by 1 and 3 microm S1P were suppressed after 1 h of preincubation with 100 nm S1P, but recovered fully after 12-24 h of exposure to S1P. Late recovery of down-regulated CT and CI, but not early down-regulation, was suppressed by PKC and PKCepsilon-selective inhibitors and was absent in T cells from PKCepsilon-null mice. The same PKCepsilon inhibitors blocked S1P-evoked increases in T cell nuclear levels of c-Fos and phosphorylated c-Jun and JunD after 24 h, but not 1 h. A mixture of c-Fos plus c-Jun antisense oligonucleotides prevented late recovery of down-regulated CT and CI, without affecting S1P induction of down-regulation. Similarly, S1P-elicited threonine phosphorylation of S1P1 Rs was suppressed by a selective inhibitor of PKCepsilon after 24 h, but not 1 h. Biochemical requisites for recovery of down-regulated S1P1 Rs thus differ from those for S1P induction of down-regulation.
authors.affiliation: Department of Medicine, University of California, San Francisco, California 94143-0711, USA.
authors.forename: Markus H
authors.initials: MH
authors.lastname: Graeler
authors.forename: Yvonne
authors.initials: Y
authors.lastname: Kong
authors.forename: Joel S
authors.initials: JS
authors.lastname: Karliner
authors.forename: Edward J
authors.initials: EJ
authors.lastname: Goetzl
mesh_terms: D000818:Animals; D015153:Blotting, Western; D015496:CD4-Positive T-Lymphocytes / Q000378:metabolism; D002465:Cell Movement; D002467:Cell Nucleus / Q000378:metabolism; D015536:Down-Regulation; D004797:Enzyme-Linked Immunosorbent Assay; D008246:Lysophospholipids; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D016376:Oligonucleotides, Antisense / Q000378:metabolism; D010766:Phosphorylation; D011493:Protein Kinase C / Q000378:metabolism / Q000502:physiology*; D051744:Protein Kinase C-epsilon; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000378:metabolism / Q000502:physiology*; D043562:Receptors, G-Protein-Coupled; D049312:Receptors, Lysophospholipid; D013110:Sphingosine / Q000031:analogs & derivatives* / Q000378:metabolism; D013601:T-Lymphocytes / Q000378:metabolism*; D013997:Time Factors; D014158:Transcription, Genetic; D014162:Transfection
chemical_list: D008246:Lysophospholipids; D016376:Oligonucleotides, Antisense; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D011956:Receptors, Cell Surface; D043562:Receptors, G-Protein-Coupled; D049312:Receptors, Lysophospholipid; C060506:sphingosine 1-phosphate; C497256:Prkce protein, mouse; D011493:Protein Kinase C; D051744:Protein Kinase C-epsilon; D013110:Sphingosine