NADPH oxidase-derived H(2)O(2) contributes to angiotensin II-induced aldosterone synthesis in human and rat adrenal cortical cells.
BACKGROUND
The Renin-Angiotensin-Aldosterone-System plays a pivotal role in hypertension. Angiotensin II (Ang II) is a major regulator of aldosterone synthesis and secretion, and it is known to facilitate reactive oxygen species (ROS) generation in many cell types.


OBJECTIVE
Here, we assessed the role of ROS signaling in Ang II-induced aldosterone synthesis by focusing on the regulation of aldosterone synthase (CYP11B2), a cytochrome P450 oxidase that catalyzes the final step in aldosterone biosynthetic pathway.


RESULTS
Ang II increased CYP11B2 activity, mRNA and protein with a concomitant elevation of 6-Carboxy- 2',7'-dichlorodihydrofluorescein diacetate fluorescence, malondialdehyde and protein carbonyl levels (indices of ROS), NADPH oxidase (Nox) activity, and H(2)O(2) levels in human and rat adrenal cortical cells. The expression of nuclear receptor related 1 protein, a transcription factor known to regulate CYP11B2 expression, was also augmented by Ang II. These Ang II-evoked effects were either abolished or attenuated by pretreatment of cells with either Ang II type I receptor (AT(1)R) antagonist, or antioxidants or Nox inhibitor or siRNA silencing of Nox1, 2 and 4, or inhibitors of phospholipase C and protein kinase C. Exogenous H(2)O(2) mimicked the facilitatory effects of Ang II on CYP11B2 activity, mRNA, and protein expression, and these changes were significantly reduced by PEG-catalase.


METHODS
ROS, particularly H(2)O(2), is identified as a key regulator of aldosterone production.


CONCLUSIONS
Our results suggest that Ang II facilitates CYP11B2 activity and the ensuing aldosterone production via activation of AT(1)R-Nox-H(2)O(2) signaling pathway.
Department of Medicine, Institute for Integrative Physiology, University of Chicago, Chicago, IL 60637-1470, USA.
Senthilkumar B
SB
Rajamohan
Gayatri
G
Raghuraman
Nanduri R
NR
Prabhakar
Ganesh K
GK
Kumar
D000302:Adrenal Cortex / Q000166:cytology / Q000201:enzymology* / Q000378:metabolism; D000450:Aldosterone / Q000096:biosynthesis*; D000804:Angiotensin II / Q000502:physiology*; D057911:Angiotensin Receptor Antagonists / Q000494:pharmacology; D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D045744:Cell Line, Tumor; D019405:Cytochrome P-450 CYP11B2 / Q000235:genetics / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D015870:Gene Expression; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D006861:Hydrogen Peroxide / Q000378:metabolism*; D066298:In Vitro Techniques; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000378:metabolism; D008297:Male; D008562:Membrane Glycoproteins / Q000378:metabolism; D008928:Mitochondria / Q000201:enzymology / Q000378:metabolism; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases / Q000037:antagonists & inhibitors / Q000378:metabolism*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors / Q000378:metabolism; D057126:Nuclear Receptor Subfamily 4, Group A, Member 2 / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D011945:Receptors, Angiotensin / Q000378:metabolism; D013481:Superoxides / Q000378:metabolism; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors / Q000378:metabolism; D015854:Up-Regulation
D057911:Angiotensin Receptor Antagonists; D000975:Antioxidants; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D008562:Membrane Glycoproteins; C539882:NR4A2 protein, human; D057126:Nuclear Receptor Subfamily 4, Group A, Member 2; D011945:Receptors, Angiotensin; D013481:Superoxides; D000804:Angiotensin II; D000450:Aldosterone; D006861:Hydrogen Peroxide; D019001:Nitric Oxide Synthase; D019405:Cytochrome P-450 CYP11B2; C056558:CYBB protein, human; D000074662:NADPH Oxidase 2; D019255:NADPH Oxidases; D010738:Type C Phospholipases