TY  - JOUR
A1  - Neuschäfer-Rube, Frank
A1  - Pathe-Neuschäfer-Rube, Andrea
A1  - Hippenstiel, Stefan
A1  - Püschel, Gerhard Paul
T1  - PGE(2) enhanced TNF alpha-mediated IL-8 induction in monocytic cell lines and PBMC
JF  - Cytokine
N2  - Background & purpose: Recent studies suggested a role of prostaglandin E-2 (PGE(2)) in the expression of the chemokine IL-8 by monocytes. The function of EP4 receptor for TNF alpha-induced IL-8 expression was studied in monocytic cell lines. Experimental approach: IL-8 mRNA and protein induction as well as IL-8 promoter activity and transcription factor activation were assessed in monocytic cell lines, primary blood mononuclear cells (PBMC) and transgenic HEK293 cells expressing the EP4 receptor. Key results: In monocytic cell lines THP-1, MonoMac and U937 PGE(2) had only a marginal impact on IL-8 induction but strongly enhanced TNFa-induced IL-8 mRNA and protein synthesis. Similarly, in PBMC IL-8 mRNA induction was larger by simultaneous stimulation with TNF alpha and PGE(2) than by either stimulus alone. The EP4 receptor subtype was the most abundant EP receptor in all three cell lines and in PBMC. Stimulation of THP-1 cells with an EP4 specific agonist enhanced TNF alpha-induced IL-8 mRNA and protein formation to the same extent as PGE(2). In HEK293 cells expressing EP4, but not in wild type HEK293 cells lacking EP4, PGE(2) enhanced TNFainduced IL-8 protein and mRNA synthesis. In THP-1 cells, the enhancement of TNF alpha-mediated IL-8 mRNA induction by PGE(2) was mimicked by a PICA-activator. Furthermore in these cells PGE(2) induced expression of transcription factor C/EBPS, enhanced NF-KB activation by TNFa and inhibited TNF alpha-mediated AP-1 activation. PGE(2) and TNF alpha synergistically activated transcription factor CREB, induced C/EBPS expression and enhanced the activity of an IL-8 promoter fragment containing-223 bp upstream of the transcription start site. Conclusions and implications: These findings suggest that a combined stimulation of TNF alpha and PGE(2)/EP4 signal chains in monocytic cells leads to maximal IL-8 promoter activity, as well as IL-8 mRNA and protein induction, by activating the PICA/CREB/C/EB1313 as well as NF-kappa B signal chains.
KW  - Monocyte
KW  - Prostaglandin receptor EP4
KW  - IL-8 transcription
KW  - Signal transduction
KW  - Tumor necrosis factor alpha
Y1  - 2018
U6  - https://doi.org/10.1016/j.cyto.2018.06.020
SN  - 1043-4666
SN  - 1096-0023
VL  - 113
SP  - 105
EP  - 116
PB  - Elsevier
CY  - London
ER  - 
TY  - JOUR
A1  - Gerhardt, Matthias
A1  - Walz, Michael
A1  - Beta, Carsten
T1  - Signaling in chemotactic amoebae remains spatially confined to stimulated membrane regions
JF  - Journal of cell science
N2  - Recent work has demonstrated that the receptor-mediated signaling system in chemotactic amoeboid cells shows typical properties of an excitable system. Here, we delivered spatially confined stimuli of the chemoattractant cAMP to the membrane of differentiated Dictyostelium discoideum cells to investigate whether localized receptor stimuli can induce the spreading of excitable waves in the G-protein-dependent signal transduction system. By imaging the spatiotemporal dynamics of fluorescent markers for phosphatidylinositol (3,4,5)-trisphosphate (PIP3), PTEN and filamentous actin, we observed that the activity of the signaling pathway remained spatially confined to the stimulated membrane region. Neighboring parts of the membrane were not excited and no receptor-initiated spatial spreading of excitation waves was observed. To generate localized cAMP stimuli, either particles that carried covalently bound cAMP molecules on their surface were brought into contact with the cell or a patch of the cell membrane was aspirated into a glass micropipette to shield this patch against freely diffusing cAMP molecules in the surrounding medium. Additionally, the binding site of the cAMP receptor was probed with different surface-immobilized cAMP molecules, confirming results from earlier ligand-binding studies.
KW  - Signal transduction
KW  - Excitable dynamics
KW  - Dictyostelium
KW  - cAMP
KW  - PIP3
KW  - PIP2
KW  - PI3K
KW  - PTEN
KW  - Micropipette aspiration
KW  - cAMP receptor
KW  - Patch clamp
Y1  - 2014
U6  - https://doi.org/10.1242/jcs.161133
SN  - 0021-9533
SN  - 1477-9137
VL  - 127
IS  - 23
SP  - 5115
EP  - 5125
PB  - Company of Biologists Limited
CY  - Cambridge
ER  -