Key result
Cardiac-specific Nox4 overexpression in mice led to an ≈10-fold increase in Nox4 protein and an 8-fold increase in reactive oxygen species, causing cardiac fibrosis and hypertrophy.
Why the study?
Does Nox4 upregulation induce cardiac remodeling and does Nox4 inhibition with GKT137831 attenuate it in a transgenic mouse model?
Does Nox4 upregulation induce cardiac remodeling and does Nox4 inhibition with GKT137831 attenuate it in a transgenic mouse model?
Answers are grounded in this paper and cite their sources.
Nox4 upregulation drives cardiac fibrosis and hypertrophy via Akt-mTOR and NFκB pathways, highlighting Nox4 inhibition as a potential therapeutic strategy for cardiac remodeling.
BACKGROUND: NADPH oxidase 4 (Nox4) has been implicated in cardiac remodeling, but its precise role in cardiac injury remains controversial. Furthermore, little is known about the downstream effector signaling pathways activated by Nox4-derived reactive oxygen species in the myocardium. We investigated the role of Nox4 and Nox4-associated signaling pathways in the development of cardiac remodeling. METHODS AND RESULTS: Cardiac-specific human Nox4 transgenic mice (c-hNox4Tg) were generated. Four groups of mice were studied: (1) control mice, littermates that are negative for hNox4 transgene but Cre positive; (2) c-hNox4 Tg mice; (3) angiotensin II (AngII)-infused control mice; and (4) c-hNox4Tg mice infused with AngII. The c-hNox4Tg mice exhibited an ≈10-fold increase in Nox4 protein expression and an 8-fold increase in the production of reactive oxygen species, and manifested cardiac interstitial fibrosis. AngII infusion to control mice increased cardiac Nox4 expression and induced fibrosis and hypertrophy. The Tg mice receiving AngII exhibited more advanced cardiac remodeling and robust elevation in Nox4 expression, indicating that AngII worsens cardiac injury, at least in part by enhancing Nox4 expression. Moreover, hNox4 transgene and AngII infusion induced the expression of cardiac fetal genes and activated the Akt-mTOR and NFκB signaling pathways. Treatment of AngII-infused c-hNox4Tg mice with GKT137831, a Nox4/Nox1 inhibitor, abolished the increase in oxidative stress, suppressed the Akt-mTOR and NFκB signaling pathways, and attenuated cardiac remodeling. CONCLUSIONS: Upregulation of Nox4 in the myocardium causes cardiac remodeling through activating Akt-mTOR and NFκB signaling pathways. Inhibition of Nox4 has therapeutic potential to treat cardiac remodeling.
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Zhao et al. (2015) studied Cardiac remodeling. Nox4 overexpression (c-hNox4Tg) and Angiotensin II infusion vs. Control mice was evaluated on Cardiac remodeling (fibrosis and hypertrophy). Cardiac-specific Nox4 overexpression in mice led to an ≈10-fold increase in Nox4 protein and an 8-fold increase in reactive oxygen species, causing cardiac fibrosis and hypertrophy.
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