Regulation of angiotensin II-stimulated osteopontin expression in cardiac microvascular endothelial cells: role of p42/44 mitogen-activated protein kinase and reactive oxygen species.
Using spontaneously hypertensive and aortic banded rats, we have shown that expression of myocardial osteopontin, an extracellular matrix protein, coincides with the development of heart failure and is inhibited by captopril, suggesting a role for angiotensin II (ANG II). This study tested whether ANG II induces osteopontin expression in adult rat ventricular myocytes and cardiac microvascular endothelial cells (CMEC), and if so, whether induction is mediated via activation of mitogen-activated protein kinases (p42/44 MAPK) and involves reactive oxygen species (ROS). ANG II (1 microM, 16 h) increased osteopontin expression (fold increase 3.3+/-0.34, n = 12, P < 0.01) in CMEC as measured by northern analysis, but not in ARVM. ANG II stimulated osteopontin expression in CMEC in a time- (within 4 h) and concentration-dependent manner, which was prevented by the AT1 receptor antagonist, losartan. ANG II elicited robust phosphorylation of p42/44 MAPK as measured using phospho-specific antibodies, and increased superoxide production as measured by cytochrome c reduction and lucigenin chemiluminescence assays. These effects were blocked by diphenylene iodonium (DPI), an inhibitor of the flavoprotein component of NAD(P)H oxidase. PD98059, an inhibitor of p42/44 MAPK pathway, and DPI each inhibited ANG II-stimulated osteopontin expression. Northern blot analysis showed basal expression of p22phox, a critical component of NADH/NADPH oxidase system, which was increased 40-60% by exposure to ANG II. These results suggest that p42/44 MAPK is a critical component of the ROS-sensitive signaling pathways activated by ANG II in CMEC and plays a key role in the regulation of osteopontin gene expression. Published 2001 Wiley-Liss, Inc.
Xie
Z
Z
Myocardial Biology Unit, Boston Medical Center, Boston Veterans Affairs Medical Center, 650 Albany Street, Boston, MA 02118, USA.
Pimental
D R
DR
Lohan
S
S
Vasertriger
A
A
Pligavko
C
C
Colucci
W S
WS
Singh
K
K
D014013:1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium Salt / Q000494:pharmacology; D000804:Angiotensin II / Q000494:pharmacology*; D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D015152:Blotting, Northern; D003331:Coronary Vessels / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007202:Indicators and Reagents / Q000494:pharmacology; D019808:Losartan / Q000494:pharmacology; D008297:Male; D026901:Membrane Transport Proteins; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism*; D009252:NADPH Dehydrogenase / Q000235:genetics / Q000378:metabolism; D019255:NADPH Oxidases; D009861:Onium Compounds / Q000494:pharmacology; D053495:Osteopontin; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D017382:Reactive Oxygen Species / Q000378:metabolism*; D012795:Sialoglycoproteins / Q000235:genetics / Q000378:metabolism*; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D000959:Antihypertensive Agents; D004791:Enzyme Inhibitors; D007202:Indicators and Reagents; D026901:Membrane Transport Proteins; D009861:Onium Compounds; D010750:Phosphoproteins; D017382:Reactive Oxygen Species; C506895:SPP1 protein, human; D012795:Sialoglycoproteins; C506897:Spp1 protein, rat; D014662:Vasoconstrictor Agents; D053495:Osteopontin; D000804:Angiotensin II; D014013:1,2-Dihydroxybenzene-3,5-Disulfonic Acid Disodium Salt; C007517:diphenyleneiodonium; D019255:NADPH Oxidases; C086986:CYBA protein, human; D009252:NADPH Dehydrogenase; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3; D020928:Mitogen-Activated Protein Kinases; D019808:Losartan