7beta-Hydroxycholesterol and 25-hydroxycholesterol-induced interleukin-8 secretion involves a calcium-dependent activation of c-fos via the ERK1/2 signaling pathway in THP-1 cells: oxysterols-induced IL-8 secretion is calcium-dependent.
Oxysterols found in oxidized low-density lipoproteins are probably involved in the appearance of atheroma; some are cytotoxic and some able to induce cytokine secretion. An oxysterol-induced interleukin-8 (IL-8) secretion in human monocytes/macrophages has been previously noticed, but the mechanisms remained unclear. In this paper, we investigated the signaling pathways leading to the induction of IL-8 secretion in monocytic THP-1 cells treated with 7beta-hydroxycholesterol, a cytototoxic oxysterol, or with 25-hydroxycholesterol, an oxysterol non-cytotoxic toward this cell line. The oxysterol-induced IL-8 secretion appears to be a calcium-dependent phenomenon as shown by the use of calcium channel blockers, which strongly decreased IL-8 secretion and IL-8 messenger RNA (mRNA) levels. Fluo-3 staining used in flow cytometry and video microscopy revealed an oxysterol-induced Ca(2+) influx, varying according to the oxysterol studied, leading to the activation of the MEK/ERK1/2 pathway as demonstrated by Western blot analysis. ERK activation led to an increase of c-fos mRNA and/or an activation of c-fos. Luciferase reporter gene assay using constructs of the human IL-8 gene promoter and Transam assay revealed the involvement of the AP-1 transcription factor in oxysterol-dependent IL-8 secretion. These results demonstrate that oxysterol-induced IL-8 secretion is a calcium-dependent phenomenon involving the MEK/ERK1/2 pathway leading to the activation of IL-8 gene via AP-1 (c-fos).
Lemaire-Ewing
Stéphanie
S
INSERM U866, Dijon, France.
Berthier
Arnaud
A
Royer
Marie Charlotte
MC
Logette
Emmanuelle
E
Corcos
Laurent
L
Bouchot
André
A
Monier
Serge
S
Prunet
Céline
C
Raveneau
Magalie
M
Rébé
Cédric
C
Desrumaux
Catherine
C
Lizard
Gérard
G
Néel
Dominique
D
D002118:Calcium / Q000378:metabolism*; D002121:Calcium Channel Blockers / Q000494:pharmacology; D002460:Cell Line; D015870:Gene Expression / Q000187:drug effects / Q000276:immunology; D006801:Humans; D006888:Hydroxycholesterols / Q000378:metabolism / Q000494:pharmacology*; D016209:Interleukin-8 / Q000235:genetics / Q000378:metabolism*; D008077:Lipoproteins, LDL / Q000378:metabolism; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000276:immunology*; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism; D009000:Monocytes / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D009543:Nifedipine / Q000494:pharmacology; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000378:metabolism; D014700:Verapamil / Q000494:pharmacology
D002121:Calcium Channel Blockers; D006888:Hydroxycholesterols; D016209:Interleukin-8; D008077:Lipoproteins, LDL; D016760:Proto-Oncogene Proteins c-fos; D012333:RNA, Messenger; D018808:Transcription Factor AP-1; C099252:oxidized low density lipoprotein; C011724:cholest-5-en-3 beta,7 alpha-diol; C007997:25-hydroxycholesterol; D014700:Verapamil; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D009543:Nifedipine; D002118:Calcium