Cross-talk between mitochondria and NADPH oxidase: effects of mild mitochondrial dysfunction on angiotensin II-mediated increase in Nox isoform expression and activity in vascular smooth muscle cells.
Mitochondria and NADPH oxidase activation are concomitantly involved in pathogenesis of many vascular diseases. However, possible cross-talk between those ROS-generating systems is unclear. We induced mild mitochondrial dysfunction due to mitochondrial DNA damage after 24 h incubation of rabbit aortic smooth muscle (VSMC) with 250 ng/mL ethidium bromide (EtBr). VSMC remained viable and had 29% less oxygen consumption, 16% greater baseline hydrogen peroxide, and unchanged glutathione levels. Serum-stimulated proliferation was unaltered at 24 h. Although PCR amplification of several mtDNA sequences was preserved, D-Loop mtDNA region showed distinct amplification of shorter products after EtBr. Such evidence for DNA damage was further enhanced after angiotensin-II (AngII) incubation. Remarkably, the normally observed increase in VSMC membrane fraction NADPH oxidase activity after AngII was completely abrogated after EtBr, together with failure to upregulate Nox1 mRNA expression. Conversely, basal Nox4 mRNA expression increased 1.6-fold, while being unresponsive to AngII. Similar loss in AngII redox response occurred after 24 h antimycin-A incubation. Enhanced Nox4 expression was unassociated with endoplasmic reticulum stress markers. Protein disulfide isomerase, an NADPH oxidase regulator, exhibited increased expression and inverted pattern of migration to membrane fraction after EtBr. These results unravel functionally relevant cross-talk between mitochondria and NADPH oxidase, which markedly affects redox responses to AngII.
Wosniak
João
J
Vascular Biology Laboratory, Heart Institute (InCor), University of São Paulo School of Medicine, São Paulo, Brazil.
Santos
Célio X C
CX
Kowaltowski
Alicia J
AJ
Laurindo
Francisco R M
FR
D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D001483:Base Sequence; D015153:Blotting, Western; D002460:Cell Line; D020552:Comet Assay; D004249:DNA Damage / Q000187:drug effects; D004272:DNA, Mitochondrial / Q000187:drug effects; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D005978:Glutathione / Q000378:metabolism; D006801:Humans; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism*; D008928:Mitochondria / Q000187:drug effects / Q000378:metabolism*; D008969:Molecular Sequence Data; D009131:Muscle, Smooth, Vascular / Q000166:cytology*; D032389:Myocytes, Smooth Muscle / Q000187:drug effects / Q000201:enzymology* / Q000378:metabolism*; D019255:NADPH Oxidases / Q000235:genetics / Q000378:metabolism*; D009589:Nitrogen Oxides / Q000378:metabolism; D010101:Oxygen Consumption / Q000235:genetics / Q000502:physiology; D016133:Polymerase Chain Reaction; D011817:Rabbits; D017382:Reactive Oxygen Species / Q000378:metabolism; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D004272:DNA, Mitochondrial; D007527:Isoenzymes; D009589:Nitrogen Oxides; D017382:Reactive Oxygen Species; D014662:Vasoconstrictor Agents; D000804:Angiotensin II; D019255:NADPH Oxidases; D005978:Glutathione