Background: Hypoxia is a well-known factor in the promotion of apoptosis, which contributes to the development of numerous cardiac diseases, such as heart failure and myocardial infarction. Inhibiting apoptosis is an important therapeutic strategy for the treatment of related heart diseases caused by ischemia/hypoxic injury. Previous studies have demonstrated that BAG3 plays an important role in cardiomyocyte apoptosis and survival. However, the role of BAG3 in hypoxia-induced cardiomyocyte apoptosis remains to be clarified. Here, we demonstrate that BAG3 is induced by hypoxia stimuli in cultured cardiomyocytes. Methods: BAG3 expression level was measured in H9c2 cells treated with hypoxia for 48 h. Cell proliferation and apoptosis were tested using MTT assay and Annexin V FITC-PI staining assay, respectively. The mRNA or protein expression level of BAG3, LC3-I, LC3-II, Atg5, NF-κB p65 and phosphorylated NF-κB p65 were assessed by qRT-PCR and western blot assay, respectively. Resluts: Overexpression of BAG3 inhibited cell apoptosis and promoted proliferation in hypoxia-injured H9c2 cells. Furthermore, autophagy and NF-κB were activated by BAG3 overexpression, and the NF-κB inhibitor PDTC could inhibit the activation of autophagy induced by BAG3 overexpression. In addition, the autophagy inhibitor 3-MA partly impeded the inhibitory effect of BAG3 on hypoxia-induced cardiomyocyte apoptosis. Conclusion: these results suggested that overexpression of BAG3 promoted cell proliferation and inhibited apoptosis by activating autophagy though the NF-κB signaling pathway in hypoxia-injured cardiomyocytes.

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Changes in land use and land cover (LULC) influence meteorological fields and biogenic emissions, further affecting the atmospheric chemistry and air quality. Combining the satellite measurements and WRF‐Chem model simulations, we evaluate the impacts of the LULC change between 2001 and 2018 on the summertime ozone (O3) formation in North China Plain and surrounding areas (NCPs). Satellite measurements have revealed that from Taihang to Yanshan Mountain, the fraction of broadleaf and needle forest coverage has increased by 5%–20% and the urban area has increased by up to 25% in the NCP. Additionally, the vegetation density has increased significantly in the NCPs except for urban areas. The LULC change generally enhances biogenic volatile compounds emissions in the NCPs, particularly over Taihang and Yanshan mountain, but the O3 variation is divergent. The maximum daily 8‐ihr average (MDA8) O3 concentrations are reduced by 1%–7% over Taihang and Yanshan Mountain because the raised vegetation density increases O3 dry deposition velocity to accelerate the O3 loss. The raised vegetation density enhances the evapotranspiration to decrease the near‐surface temperature by 0.1°C–1.5°C, which also generates a divergence in the low‐level atmosphere in the NCPs, causing secondary northerly or easterly winds in the NCP. The O3 enhancement along the coastal areas of the NCP is attributed to the perturbation of wind fields and photolysis induced by the LULC change. The divergent variation of the MDA8 O3 concentrations in the NCP is generally caused by the variations of biogenic emissions and photolysis.

Transboundary transport plays an important role in air pollution formation in China. The coastal area of south China (CA‐SCHN) frequently experiences air pollution in spring and autumn, but the contribution of transboundary transport to the air quality is still not clear. Meteorological field analyses reveal that large‐scale synoptic patterns over east China in spring and autumn provide favorable situations facilitating southward transport of air pollutants originated from the North China Plain (NCP) and Yangtze River Delta (YRD). A springtime case study using the WRF‐Chem model shows that trans‐boundary transport of air pollutants from the NCP and YRD contributes to 27% and 46% of ozone (O3) and fine particulate matter (PM2.5) concentrations in the CA‐SCHN, respectively. In the autumn case, the contribution is around 11% for O3 and 24% for PM2.5. In the spring, air pollutants in the NCP and YRD are transported over seas by large‐scale synoptic systems to the South China Sea and re‐circulated by the sea breeze to the CA‐SCHN during daytime. In the autumn, the transport is driven by northerly winds over the land induced by large‐scale synoptic systems, and is also modulated by the local mountain‐valley breeze circulation. The results provide support for design and implementation of air pollutants control strategies in the CA‐SCHN.