title: AMP-activated protein kinase mediates T cell activation-induced expression of FasL and COX-2 via protein kinase C theta-dependent pathway in human Jurkat T leukemia cells.
abstract: AMP-activated protein kinase (AMPK), an important regulator of energy homeostasis, is known to be activated during T cell activation. T cell activation by T cell receptor (TCR) engagement or its pharmacological mimics, PMA plus ionomycin (PMA/Io), induces immunomodulatory FasL and cyclooxygenase-2 (COX-2) expression. In this study, we examined the role and mechanisms of AMPK in PMA/Io-induced expression of FasL and COX-2 in Jurkat T human leukemic cells. Inhibition of AMPK by a pharmacological agent, compound C, or AMPKα1 siRNA suppressed expression of FasL and COX-2 mRNAs and proteins in PMA/Io-activated Jurkat cells. It also reduced secretion of FasL protein and prostaglandin E2, a main product of COX-2, in Jurkat cells and peripheral blood lymphocytes activated with PMA/Io or monoclonal anti-CD3 plus anti-CD28. Consistently, inhibition of AMPK blocked promoter activities of FasL and COX-2 in activated Jurkat cells. As protein kinase C theta (PKCθ) is a central molecule for TCR signaling, we examined any possible cross-talk between AMPK and PKCθ in activated T cells. Of particular importance, we found that inhibition of AMPK blocked phosphorylation and activation of PKCθ, suggesting that AMPK is an upstream kinase of PKCθ. Moreover, we showed that AMPK was directly associated with PKCθ and phosphorylated Thr538 of PKCθ in PMA/Io-stimulated Jurkat cells. We also showed that inhibition of PKCθ by rottlerin or dominant negative PKCθ reduced AMPK-mediated transcriptional activation of NF-AT and AP-1 in activated Jurkat cells. Taken together, these results suggest that AMPK regulates expression of FasL and COX-2 via the PKCθ and NF-AT and AP-1 pathways in activated Jurkat cells.
authors.affiliation: Department of Biochemistry and Molecular Biology, School of Medicine, Medical Research Center for Bioreaction to Reactive Oxygen Species, Biomedical Science Institute, Kyung Hee University, Seoul 130-701, Republic of Korea.
authors.forename: Jung Yeon
authors.initials: JY
authors.lastname: Lee
authors.forename: A-Young
authors.initials: AY
authors.lastname: Choi
authors.forename: Young Taek
authors.initials: YT
authors.lastname: Oh
authors.forename: Wonchae
authors.initials: W
authors.lastname: Choe
authors.forename: Eui-Ju
authors.initials: EJ
authors.lastname: Yeo
authors.forename: Joohun
authors.initials: J
authors.lastname: Ha
authors.forename: Insug
authors.initials: I
authors.lastname: Kang
mesh_terms: D055372:AMP-Activated Protein Kinases / Q000276:immunology*; D051546:Cyclooxygenase 2 / Q000235:genetics*; D053222:Fas Ligand Protein / Q000235:genetics*; D005786:Gene Expression Regulation; D006801:Humans; D007527:Isoenzymes / Q000276:immunology*; D019169:Jurkat Cells; D008213:Lymphocyte Activation; D011493:Protein Kinase C / Q000276:immunology*; D000074121:Protein Kinase C-theta; D015398:Signal Transduction; D013601:T-Lymphocytes / Q000166:cytology* / Q000276:immunology
chemical_list: C505661:FASLG protein, human; D053222:Fas Ligand Protein; D007527:Isoenzymes; D051546:Cyclooxygenase 2; C076233:PRKCQ protein, human; D011493:Protein Kinase C; D000074121:Protein Kinase C-theta; D055372:AMP-Activated Protein Kinases