[Angiotensin II up-regulates osteopontin mRNA expression of RAW264.7 macrophages via p38MAPK signaling].
OBJECTIVE
To investigate the changes of osteopontin (OPN) mRNA expression induced by angiotensin II (AngII) in RAW264.7 macrophages, and to determine the role of p38 mitogen-activated protein kinase (p38MAPK) signaling in up-regulation of OPN mRNA expression.


METHODS
RT-PCR was used for examining the OPN mRNA expression, and the phosphorylation of p38MAPK and activating transcription factor2 (ATF2) was detected by Western blot.


RESULTS
(1) AngII (1 micromol/L) enhanced the expression of OPN mRNA in RAW264.7 macrophages with time-dependent, including 0.9 fold, 2.3 folds and 2.4 folds up-regulation at 6, 12, 24 h, respectively (all P < 0.01), whereas there was no significant change in negative control at 0 h and 24 h, suggesting that the mRNA expression of OPN is inducible. (2) Following excitation by Ang II in vitro, there was substantial up-regulation of OPN mRNA expression in RAW264.7 macrophages with dose-dependent; with a dose of 1 micromol/L incubated for 12 h, Ang II increased the OPN mRNA expression by 2.6 folds (P < 0.01). (3) Pre-treatment with SB202190 (5 micromol/L) for 30 min in RAW264.7 macrophages before AngII (1 micromol/L) used, the expression of OPN mRNA was inhibited by 61.7% (P < 0.01); but no marked inhibition had happened at the time of treatment with both SB202190 (5 micromol/L) and Ang II (1 micromol/L) added at the same time and with SB202190 (5 micromol/L) for 120 min after Ang II (1 micromol/L) used. (4) Pre-treatment with SB202190 (1, 5, 10 micromol/L) for 30 min in RAW264.7 macrophages before Ang II (1 micromol/L) used, the expression of OPN mRNA was decreased by 43.4%, 63.0% and 65.5%, respectively (all P < 0.01). (5) There was a maximal expression of p38MAPK phosphorylation at 15 approximately 30 min induced by Ang II (1 micromol/L) in RAW264.7 macrophages, and the maximal expression of phosphorylated ATF2 was at 30 approximately 45 min. (6) Pre-treatment with SB202190 (1, 5 micromol/L) for 30 min in RAW264.7 macrophages before Ang II (1 micromol/L) used, the expression of p38MAPK phosphorylation was inhibited markedly with dose-dependent, and the phosphorylation of p38MAPK was decreased by 61.7% (P < 0.01) after the SB202190 (5 micromol/L) was used.


CONCLUSIONS
Angiotensin II may up-regulate osteopontin mRNA expression of RAW264.7 macrophages via p38MAPK signaling.
Lou
Ning
N
Department of Nephrology, The First Affiliated Hospital, Sun Yat-sen University, Guangzhou 510080, China.
Yu
Xue-qing
XQ
Zhu
Sheng-lang
SL
Zheng
Xun-hua
XH
Dong
Xiu-qing
XQ
Li
Xiao-yan
XY
D000804:Angiotensin II / Q000494:pharmacology*; D002460:Cell Line; D006801:Humans; D008264:Macrophages / Q000166:cytology / Q000378:metabolism*; D053495:Osteopontin; D010766:Phosphorylation; D012333:RNA, Messenger / Q000096:biosynthesis / Q000235:genetics; D012795:Sialoglycoproteins / Q000096:biosynthesis* / Q000235:genetics; D015398:Signal Transduction; D015854:Up-Regulation; D048051:p38 Mitogen-Activated Protein Kinases / Q000502:physiology*
D012333:RNA, Messenger; C506895:SPP1 protein, human; D012795:Sialoglycoproteins; D053495:Osteopontin; D000804:Angiotensin II; D048051:p38 Mitogen-Activated Protein Kinases