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KMID : 0620920220540050662
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Experimental & Molecular Medicine
2022 Volume.54 No. 5 p.662 ~ p.672
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Overexpression of V-ATPase B2 attenuates lung injury/fibrosis by stabilizing lysosomal membrane permeabilization and increasing collagen degradation
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Lee Jong-Uk
Hong Ji-Su
Shin Hye-Sun
Ryu Chnag-Beom
Park Sung-Woo
Jeong Sung-Hwan
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Abstract
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Excessive oxidative stress causes lysosomal membrane permeabilization (LMP), which leads to cell death. Vacuolar ATPase (V-ATPase) is the enzyme responsible for pumping H+ into the cytosol and thus maintaining intracellular pH. Previously, we reported that V-ATPase B2 subunit expression is upregulated in the TiO2-exposed lung epithelium. We investigated the role of the lysosomal V-ATPase B2 subunit in oxidative stress-induced alveolar epithelial cell death and in an experimental lung injury/fibrosis model. Overexpression of V-ATPase B2 increased lysosomal pH and lysosomal activities in the cells. In the presence of H2O2, overexpression of V-ATPase B2 increased survival, and silencing of V-ATPase B2 dramatically increased cell death. Overexpression of V-ATPase B2 diminished H2O2-triggered LMP, as evidenced by a reduction in acridine orange staining and leakage of cathepsin D from the lysosome to the cytoplasm. In addition, V-ATPase B2-overexpressing macrophages exhibited significantly enhanced uptake and degradation of collagen. V-ATPase B2-overexpressing transgenic mice showed significant inhibition of the bleomycin-induced increases in lung inflammation and fibrosis. We conclude that V-ATPase B2 is critical for maintaining lysosomal activities against excessive oxidative stress by stabilizing LMP. Our findings reveal a previously unknown role of this V-ATPase subunit in a lung injury and fibrosis model.
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KEYWORD
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Cell adhesion, Experimental models of disease
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