Lysocardiolipin acyltransferase regulates TGF-β mediated lung fibroblast differentiation.

Lysocardiolipin acyltransferase (LYCAT), a cardiolipin remodeling enzyme, plays a key role in mitochondrial function and vascular development. We previously reported that reduced LYCAT mRNA levels in peripheral blood mononuclear cells correlated with poor pulmonary function outcomes and decreased survival in IPF patients. Further LYCAT overexpression reduced lung fibrosis, and LYCAT knockdown accentuated experimental pulmonary fibrosis. NADPH Oxidase 4 (NOX4) expression and oxidative stress are known to contribute to lung fibroblast differentiation and progression of fibrosis. In this study, we investigated the role of LYCAT in TGF-β mediated differentiation of human lung fibroblasts to myofibroblasts, and whether this occurred through mitochondrial superoxide and NOX4 mediated hydrogen peroxide (H2O2) generation. Our data indicated that LYCAT expression was up-regulated in primary lung fibroblasts isolated from IPF patients and bleomycin-challenged mice, compared to controls. In vitro, siRNA-mediated SMAD3 depletion inhibited TGF-β stimulated LYCAT expression in human lung fibroblasts. ChIP immunoprecipitation assay revealed TGF-β stimulated SMAD2/3 binding to the endogenous LYCAT promoter, and mutation of the SMAD2/3 binding sites (-179/-183 and -540/-544) reduced TGF-β-stimulated LYCAT promoter activity. Overexpression of LYCAT attenuated TGF-β-induced mitochondrial and intracellular oxidative stress, NOX4 expression and differentiation of human lung fibroblasts. Further, pretreatment with Mito-TEMPO, a mitochondrial superoxide scavenger, blocked TGF-β-induced mitochondrial superoxide, NOX4 expression and differentiation of human lung fibroblasts. Treatment of human lung fibroblast with NOX1/NOX4 inhibitor, GKT137831, also attenuated TGF-β induced fibroblast differentiation and mitochondrial oxidative stress. Collectively, these results suggest that LYCAT is a negative regulator of TGF-β-induced lung fibroblast differentiation by modulation of mitochondrial superoxide and NOX4 dependent H2O2 generation, and this may serve as a potential therapeutic target for human lung fibrosis.

Huang LS ，Jiang P ，Feghali-Bostwick C ，Reddy SP ，Garcia JGN ，Natarajan V ... -  《-》

The mitochondrial cardiolipin remodeling enzyme lysocardiolipin acyltransferase is a novel target in pulmonary fibrosis.

Huang LS ，Mathew B ，Li H ，Zhao Y ，Ma SF ，Noth I ，Reddy SP ，Harijith A ，Usatyuk PV ，Berdyshev EV ，Kaminski N ，Zhou T ，Zhang W ，Zhang Y ，Rehman J ，Kotha SR ，Gurney TO ，Parinandi NL ，Lussier YA ，Garcia JG ，Natarajan V ... -  《-》

Metformin attenuates lung fibrosis development via NOX4 suppression.

Sato N ，Takasaka N ，Yoshida M ，Tsubouchi K ，Minagawa S ，Araya J ，Saito N ，Fujita Y ，Kurita Y ，Kobayashi K ，Ito S ，Hara H ，Kadota T ，Yanagisawa H ，Hashimoto M ，Utsumi H ，Wakui H ，Kojima J ，Numata T ，Kaneko Y ，Odaka M ，Morikawa T ，Nakayama K ，Kohrogi H ，Kuwano K ... -  《RESPIRATORY RESEARCH》

EM703 improves bleomycin-induced pulmonary fibrosis in mice by the inhibition of TGF-beta signaling in lung fibroblasts.

Li YJ ，Azuma A ，Usuki J ，Abe S ，Matsuda K ，Sunazuka T ，Shimizu T ，Hirata Y ，Inagaki H ，Kawada T ，Takahashi S ，Kudoh S ，Omura S ... -  《RESPIRATORY RESEARCH》

Regulation of mitochondrial oxidative stress by β-arrestins in cultured human cardiac fibroblasts.

Oxidative stress in cardiac fibroblasts (CFs) promotes transformation to myofibroblasts and collagen synthesis leading to myocardial fibrosis, a precursor to heart failure (HF). NADPH oxidase 4 (Nox4) is a major source of cardiac reactive oxygen species (ROS); however, mechanisms of Nox4 regulation are unclear. β-arrestins are scaffold proteins that signal in G-protein-dependent and -independent pathways; for example, in ERK activation. We hypothesize that β-arrestins regulate oxidative stress in a Nox4-dependent manner and increase fibrosis in HF. CFs were isolated from normal and failing adult human left ventricles. Mitochondrial ROS/superoxide production was quantitated using MitoSox. β-arrestin and Nox4 expressions were manipulated using adenoviral overexpression or short interfering RNA (siRNA)-mediated knockdown. Mitochondrial oxidative stress and Nox4 expression in CFs were significantly increased in HF. Nox4 knockdown resulted in inhibition of mitochondrial superoxide production and decreased basal and TGF-β-stimulated collagen and α-SMA expression. CF β-arrestin expression was upregulated fourfold in HF. β-arrestin knockdown in failing CFs decreased ROS and Nox4 expression by 50%. β-arrestin overexpression in normal CFs increased mitochondrial superoxide production twofold. These effects were prevented by inhibition of either Nox or ERK. Upregulation of Nox4 seemed to be a primary mechanism for increased ROS production in failing CFs, which stimulates collagen deposition. β-arrestin expression was upregulated in HF and plays an important and newly identified role in regulating mitochondrial superoxide production via Nox4. The mechanism for this effect seems to be ERK-mediated. Targeted inhibition of β-arrestins in CFs might decrease oxidative stress as well as pathological cardiac fibrosis.

Philip JL ，Razzaque MA ，Han M ，Li J ，Theccanat T ，Xu X ，Akhter SA ... -  《-》