Role of HuR and p38MAPK in ultraviolet B-induced post-transcriptional regulation of COX-2 expression in the human keratinocyte cell line HaCaT.
COX-2 (cyclooxygenase-2) is a pivotal player in inflammatory processes, and ultraviolet radiation is a known stimulus for COX-2 expression in skin cells. Here, an induction of COX-2 expression in HaCaT human keratinocytes was observed only upon exposure of cells to UVB (280-320 nm) but not to UVA radiation (320-400 nm), as demonstrated by reverse transcription-PCR and Western blotting. Prostaglandin E(2) levels were elevated in cell culture supernatants of HaCaT cells exposed to UVB. COX-2 mRNA stability was dramatically increased by UVB irradiation. Both the stabilization of COX-2 mRNA and the enhancement of COX-2 steady-state mRNA and protein levels caused by UVB were prevented both by inhibition and small interfering RNA-induced depletion of p38(MAPK), a kinase strongly activated upon exposure to UVB, suggesting p38(MAPK)-dependent mRNA stabilization as a mechanism of UVB-induced COX-2 expression. A dramatic decrease in COX-2 expression induced by UVB was elicited by small interfering RNA-based depletion of a stress-responsive mRNA stabilizing protein regulated by p38(MAPK), i.e. HuR; UVB-induced elevation of COX-2 mRNA and protein levels coincided with an accumulation of HuR in the cytoplasm and was attenuated in cells depleted of HuR. Moreover, UVB-induced generation of prostaglandin E(2) by HaCaT cells was blunted by HuR depletion, suggesting that stress kinases (such as p38(MAPK)) as well as HuR are excellent targets for approaches aiming at interfering with induction of COX-2 expression by UVB.
Fernau
Niklas S
NS
From the Leibniz-Institut für Umweltmedizinische Forschung, D-40225 Düsseldorf, Germany.
Fugmann
Dominik
D
From the Leibniz-Institut für Umweltmedizinische Forschung, D-40225 Düsseldorf, Germany.
Leyendecker
Martin
M
From the Leibniz-Institut für Umweltmedizinische Forschung, D-40225 Düsseldorf, Germany.
Reimann
Kerstin
K
From the Leibniz-Institut für Umweltmedizinische Forschung, D-40225 Düsseldorf, Germany.
Grether-Beck
Susanne
S
From the Leibniz-Institut für Umweltmedizinische Forschung, D-40225 Düsseldorf, Germany.
Galban
Stefanie
S
From the Leibniz-Institut für Umweltmedizinische Forschung, D-40225 Düsseldorf, Germany.
Ale-Agha
Niloofar
N
From the Leibniz-Institut für Umweltmedizinische Forschung, D-40225 Düsseldorf, Germany.
Krutmann
Jean
J
From the Leibniz-Institut für Umweltmedizinische Forschung, D-40225 Düsseldorf, Germany.
Klotz
Lars-Oliver
LO
From the Leibniz-Institut für Umweltmedizinische Forschung, D-40225 Düsseldorf, Germany. Electronic address: LarsOliver.Klotz@uni-duesseldorf.de.
D000954:Antigens, Surface / Q000235:genetics / Q000378:metabolism*; D015153:Blotting, Western; D002460:Cell Line; D002470:Cell Survival / Q000528:radiation effects; D051546:Cyclooxygenase 2 / Q000235:genetics* / Q000378:metabolism; D003593:Cytoplasm / Q000378:metabolism / Q000528:radiation effects; D015232:Dinoprostone / Q000378:metabolism; D004307:Dose-Response Relationship, Radiation; D051959:ELAV Proteins; D000067780:ELAV-Like Protein 1; D005786:Gene Expression Regulation / Q000528:radiation effects; D015971:Gene Expression Regulation, Enzymologic / Q000528:radiation effects; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D015603:Keratinocytes / Q000166:cytology / Q000378:metabolism / Q000528:radiation effects*; D008301:Maleimides / Q000494:pharmacology; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D034622:RNA Interference; D020871:RNA Stability / Q000528:radiation effects; D016601:RNA-Binding Proteins / Q000235:genetics / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014466:Ultraviolet Rays; D048051:p38 Mitogen-Activated Protein Kinases / Q000235:genetics / Q000378:metabolism*
D000954:Antigens, Surface; D051959:ELAV Proteins; D000067780:ELAV-Like Protein 1; C098770:ELAVL1 protein, human; D007211:Indoles; D008301:Maleimides; D016601:RNA-Binding Proteins; D051546:Cyclooxygenase 2; C496540:PTGS2 protein, human; D011493:Protein Kinase C; D048051:p38 Mitogen-Activated Protein Kinases; D015232:Dinoprostone; C088060:bisindolylmaleimide