Angiotensin II-induced over-activation of p47phox in fibroblasts from hypertensives: which role in the enhanced ERK1/2 responsiveness to angiotensin II?
BACKGROUND
Fibroblasts are involved in the remodeling of the heart and of the vasculature associated to arterial hypertension, and an abnormal extracellular signal-regulated kinase 1/2 (ERK1/2) activation by angiotensin II (Ang II) plays a pivotal role in this process. However, the intracellular pathways leading to cell hypertrophy and hyperplasia, as well as to collagen production, are still incompletely known.


OBJECTIVE
To investigate the role of superoxide anion (O2) and of nicotinamide adenine dinucleotide phosphate (NAD(P)H) oxidase in Ang II-stimulated ERK1/2 over-activation in fibroblasts from hypertensive patients.


METHODS
O2 production was measured in skin fibroblasts from hypertensives (HT, n = 11) and from normotensive controls (NT, n = 10) by electron spin resonance technique. ERK1/2 phosphorylation and p47phox NAD(P)H oxidase subunit translocation were measured by western blot.


RESULTS
Ang II (1 micromol/l) induced a larger p47phox subunit translocation and increased intracellular O2 production to a larger extent in HT in comparison to NT and this effect was blocked by apocynin, an inhibitor of the NAD(P)H oxidase. Ang II increased ERK1/2 phosphorylation more in HT than in NT. The Ang II-induced ERK1/2 phosphorylation was inhibited by apocynin in a dose-dependent manner in NT, but not in HT.


CONCLUSIONS
The chain of cellular events leading to increased ERK1/2 responsiveness to Ang II in hypertension include an exaggerated response of p47phox, NAD(P)H oxidase and O2, but it is partially resistant to apocynin. Therefore, NAD(P)H-dependent reactive oxygen species (ROS) production is not the only determinant of the exaggerated ERK1/2 responsiveness in fibroblasts of hypertensives (HT).
Papparella
Italia
I
Department of Clinical and Experimental Medicine, University of Padova Medical School, Padova, Italy.
Ceolotto
Giulio
G
Lenzini
Livia
L
Mazzoni
Martina
M
Franco
Lorenzo
L
Sartori
Michelangelo
M
Ciccariello
Laura
L
Semplicini
Andrea
A
D000098:Acetophenones / Q000494:pharmacology; D000328:Adult; D000804:Angiotensin II / Q000378:metabolism* / Q000494:pharmacology; D000975:Antioxidants / Q000494:pharmacology; D002462:Cell Membrane / Q000201:enzymology; D002478:Cells, Cultured; D003600:Cytosol / Q000201:enzymology; D005347:Fibroblasts / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D005609:Free Radicals / Q000378:metabolism; D006801:Humans; D006973:Hypertension / Q000378:metabolism*; D020935:MAP Kinase Signaling System / Q000187:drug effects / Q000502:physiology; D008875:Middle Aged; D019950:Mitogen-Activated Protein Kinase 1 / Q000378:metabolism*; D048052:Mitogen-Activated Protein Kinase 3 / Q000378:metabolism*; D019255:NADPH Oxidases; D010750:Phosphoproteins / Q000378:metabolism*; D010766:Phosphorylation / Q000187:drug effects; D017382:Reactive Oxygen Species / Q000378:metabolism; D014662:Vasoconstrictor Agents / Q000378:metabolism* / Q000494:pharmacology
D000098:Acetophenones; D000975:Antioxidants; D005609:Free Radicals; D010750:Phosphoproteins; D017382:Reactive Oxygen Species; D014662:Vasoconstrictor Agents; D000804:Angiotensin II; C056165:acetovanillone; D019255:NADPH Oxidases; C060505:neutrophil cytosolic factor 1; D019950:Mitogen-Activated Protein Kinase 1; D048052:Mitogen-Activated Protein Kinase 3