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
Authors: A-Young Choi
Young Taek Oh
Wonchae Choe
Joohun Ha
Insug Kang
Jung Yeon Lee
Eui-Ju Yeo
Journal: Cellular Signalling (2012)
Discipline: MOLECULAR BIOLOGY & GENETICS
Keywords: AMP-activated protein kinase (AMPK); T cell activation; FasL; COX-2; PMA/Io
Affiliations: 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.

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. 

Retracted: No

PubPeer comments:
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 This is one of the many papers that uses rottlerin as a means to inhibit this isoform of PKC. Yet rottlerin has no such effect on the purified enzyme (see Davies et al., Biochem. J. (2000) 351, 95u2013105 and Bain et al. Biochem. J. (2007) 408, 297u2013315). Therefore, the effects of rottlerin in cells and animals have to be mediated indirectly on PKC theta , 
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 Interestingly, the article has a Corrigendum (published December 2018) which addresses western blot figures not yet brought up in the above comments: https: doi.org 10.1016 j.cellsig.2018.09.015  *The authors regret that there were errors in the western blot data for PKCu03b8 (Fig. 5A) and u03b1-tubulin band (Fig. 8B) of the above paper. The corrected Figs. 5A and 8B are shown below. The corrections do not influence either the validity of the published data or the conclusion described in the paper. The authors would like to apologise for any inconvenience caused.* **Corrected figures:** ![file] **Original figures:** Figure 5A ![file] Figure 8B ![file] This article would really benefit from making the original uncropped WB data available. Could the authors please check the concerns mentioned above? , 
 The RT-PCR GAPDH band in Figure 8A and the alpha-tubulin blot in Figure 8B simply inverted color and reused the same image with different name. ![file] ,