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Crosstalk between mitochondrial damage and NAD(P)H oxidase activity in vascular smooth muscle cells
Author(s) -
Júnior João Wosniak,
Santos Célio X. C.,
Laurindo Francisco R.M.
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a724-a
Subject(s) - oxidative stress , nadph oxidase , endoplasmic reticulum , nad(p)h oxidase , chemistry , nad+ kinase , unfolded protein response , oxidase test , reactive oxygen species , endocrinology , medicine , xanthine oxidase , vascular smooth muscle , microbiology and biotechnology , biology , biochemistry , enzyme , smooth muscle
Vascular aging and pathological processes involve mitochondrial (MT) DNA mutations, which lead to MT stress/dysfunction. Possible crosstalk between MT damage and oxidative stress sources such as NAD(P)H oxidase is unknown. Coupling of endoplasmic reticulum (ER) stress to disrupted MT Ca++ signaling was recently shown (Xu et al, 2004). We showed that interaction between ER‐resident protein disulfide isomerase (PDI) and NAD(P)H oxidase is a pathway bridging ER and oxidative stress. Thus, we asked whether MT damage induces ER stress‐linked NAD(P)H oxidase activation. We validated a model of acute mitochondrial stress/dysfunction with minimal DNA damage induced by 24 h‐incubation of rabbit aortic smooth muscle (VSMC) or HEK293 cells with ethidium bromide (EB, 250ng/mL). In this model, VSMC do not undergo apoptosis nor change cell counts at baseline, with angiotensin II (AII) or with serum. Serum‐stimulated proliferation decreased by 31% at 72 hs. VSMC membrane fraction NADPH oxidase activity (lucigenin or Amplex Red assays) was increased by 30–50% after EB, at levels similar to known VSMC oxidase agonists. However, oxidase activation due to AII (100nM, 4h) was markedly abrogated. GSH/GSSG ratio decreased ~40% after EB. After EB, there was increased expression of p22phox subunit and PDI and increased PDI migration to membrane fraction. However, we were unable to show increased expression of ER stress markers Grp78 and Grp94. Thus, MT stress/dysfunction leads to increased baseline NADPH oxidase activity in connection with ER stress‐independent PDI overexpression, but decreased redox signals due to AII. (FAPESP)