Murine TRAIL (TNF-related apoptosis inducing ligand) expression induced by T cell activation is blocked by rapamycin, cyclosporin A, and inhibitors of phosphatidylinositol 3-kinase, protein kinase C, and protein tyrosine kinases: evidence for TRAIL induction via the T cell receptor signaling pathway.
TRAIL (TNF-related apoptosis inducing ligand), like other members of the TNF family of proteins, is able to induce apoptosis in sensitive target cells. Recently, cell-surface TRAIL has been shown to be expressed by activated human and mouse T lymphocytes, raising the possibility that TRAIL might be involved in T cell-mediated cytotoxicity and/or immune regulation. In the present study we show by semiquantitative reverse transcriptase polymerase chain reaction (RT-PCR) analysis that activated, but not resting, mouse T cells express abundant TRAIL mRNA. TRAIL transcripts were detectable within 4 h of T cell activation. A panel of pharmacologic inhibitors was used to investigate the signal transduction pathways involved in TRAIL gene induction following T lymphocyte activation. TRAIL gene expression was sensitive to the src-like protein tyrosine kinase (PTK) inhibitor herbimycin A, as well as the more general PTK inhibitor genistein, suggesting the involvement of a src family PTK. The PKC inhibitors staurosporine and calphostin C, and the phosphatidylinositol 3-kinase (PI3-K) inhibitors wortmannin and LY294002, also prevented TRAIL mRNA transcription by activated T cells, indicating a role for PKC and PI3-K. In addition, TRAIL induction was inhibited by cyclosporin A, implicating the Ca(2+)/calmodulin-dependent protein phosphatase calcineurin. TRAIL expression was also blocked by rapamycin, which inhibits p70 S6 kinase involved in CD28 and interleukin (IL)-2 receptor signaling. However, TRAIL mRNA expression was not induced by IL-2, suggesting that TRAIL gene induction is not coupled to the IL-2 receptor. Data obtained by RT-PCR were confirmed at the protein level by immunoblotting with TRAIL-specific antibody. We conclude that TRAIL gene induction is initiated through a T cell receptor-associated signaling pathway similar to that responsible for the expression of cytokine genes such as IL-2.
Musgrave
B L
BL
Department of Microbiology and Immunology, Dalhousie University, Halifax, Nova Scotia, B3H 4H7, Canada.
Phu
T
T
Butler
J J
JJ
Makrigiannis
A P
AP
Hoskin
D W
DW
D000818:Animals; D017209:Apoptosis; D051017:Apoptosis Regulatory Proteins; D001483:Base Sequence; D016572:Cyclosporine / Q000494:pharmacology; D017931:DNA Primers / Q000235:genetics; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D015870:Gene Expression / Q000187:drug effects; D006801:Humans; D066298:In Vitro Techniques; D008024:Ligands; D008213:Lymphocyte Activation; D008562:Membrane Glycoproteins / Q000235:genetics*; D051379:Mice; D008810:Mice, Inbred C57BL; D000081082:Phosphoinositide-3 Kinase Inhibitors; D011493:Protein Kinase C / Q000037:antagonists & inhibitors; D011505:Protein-Tyrosine Kinases / Q000037:antagonists & inhibitors; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D011948:Receptors, Antigen, T-Cell / Q000378:metabolism; D015398:Signal Transduction; D020123:Sirolimus / Q000494:pharmacology; D013601:T-Lymphocytes / Q000276:immunology*; D053221:TNF-Related Apoptosis-Inducing Ligand; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics*
D051017:Apoptosis Regulatory Proteins; D017931:DNA Primers; D004791:Enzyme Inhibitors; D008024:Ligands; D008562:Membrane Glycoproteins; D000081082:Phosphoinositide-3 Kinase Inhibitors; D012333:RNA, Messenger; D011948:Receptors, Antigen, T-Cell; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; C505654:Tnfsf10 protein, mouse; D014409:Tumor Necrosis Factor-alpha; D016572:Cyclosporine; D011505:Protein-Tyrosine Kinases; D011493:Protein Kinase C; D020123:Sirolimus