Differential requirement of members of the MAPK family for CCL2 expression by hepatic stellate cells.
Hepatic stellate cells (HSC) coordinate the liver wound-healing response through secretion of several cytokines and chemokines, including CCL2 (formerly known as monocyte chemoattractant protein-1). In this study, we evaluated the role of different proteins of the MAPK family (ERK, p38(MAPK), and JNK) in the regulation of CCL2 expression by HSC, as an index of their proinflammatory activity. Several mediators activated all three MAPK, including TNF, IL-1, and PDGF. To assess the relative role of the different MAPKs, specific pharmacological inhibitors were used; namely, SB203580 (p38(MAPK)), SP600125 (JNK), and PD98059 (MEK/ERK). The efficacy and specificity of the different inhibitors in our cellular system were verified analyzing the enzymatic activity of the different MAPKs using in vitro kinase assays and/or testing the inhibition of phosphorylation of downstream substrates. SB203580 and SP600125 dose-dependently inhibited CCL2 secretion and gene expression induced by IL-1 or TNF. In contrast, inhibition of ERK did not affect the upregulation of CCL2 induced by the two cytokines. Finally, activin A was also found to stimulate CCL2 expression and to activate ERK, JNK, p38, and their downstream targets. Unlike in cells exposed to proinflammatory cytokines, all three MAPKs were required to induce CCL2 secretion in response to activin. We conclude that members of the MAPK family differentially regulate cytokine-induced chemokine expression in human HSC.
Marra
Fabio
F
Dipartimento di Medicina Interna, University of Florence, Viale Morgagni 85, I-50137 Florence, Italy. f.marra@dmi.unifi.it
Delogu
Wanda
W
Petrai
Ilaria
I
Pastacaldi
Sabrina
S
Bonacchi
Andrea
A
Efsen
Eva
E
Aleffi
Sara
S
Bertolani
Cristiana
C
Pinzani
Massimo
M
Gentilini
Paolo
P
D028341:Activins / Q000494:pharmacology; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D022781:Hepatocytes / Q000378:metabolism*; D006801:Humans; D028322:Inhibin-beta Subunits / Q000494:pharmacology; D007375:Interleukin-1 / Q000494:pharmacology; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases / Q000502:physiology*; D010982:Platelet-Derived Growth Factor / Q000494:pharmacology; D014409:Tumor Necrosis Factor-alpha / Q000494:pharmacology; D048051:p38 Mitogen-Activated Protein Kinases
D004791:Enzyme Inhibitors; D007375:Interleukin-1; D010982:Platelet-Derived Growth Factor; D014409:Tumor Necrosis Factor-alpha; C422405:activin A; D028341:Activins; D028322:Inhibin-beta Subunits; D048031:JNK Mitogen-Activated Protein Kinases; D020928:Mitogen-Activated Protein Kinases; D048051:p38 Mitogen-Activated Protein Kinases