Elimination of dysfunctional mitochondria through mitophagy suppresses benzo[a]pyrene-induced apoptosis

Benzo(a)pyrene inhibits endometrial cell apoptosis in early pregnant mice via the WNT5A pathway

Benzo(a)pyrene (BaP) is an endocrine-disrupting pollutant present in various aspects of daily life, and studies have demonstrated that BaP exerts reproductive toxicity. We previously showed that BaP damages endometrial morphology and decreases the number of implantation sites in early pregnant mice, but the mechanisms underlying these effects remain unclear. The endometrial function is crucial for implantation, which is associated with endometrial cell apoptosis. In this study, we focused on the effect of BaP on endometrial cell apoptosis and the role of WNT signaling during this process. Pregnant mice were gavaged with corn oil (control group) or 0.2 mg·kg^-1 ·day ^-1 BaP (treatment group) from Days 1 to 6 of pregnancy. BaP impaired endometrial function by decreasing the expression of HOXA10 and BMP2, two markers of receptivity and decidualization. WNT5A and β-catenin were activated in the BaP group. BaP affected the expression of apoptosis-related proteins and inhibited the apoptosis of endometrial stromal cells. In vitro, human endometrial stromal cells (HESCs) were treated with different concentrations of BaP (dimethyl sulfoxide (DMSO); 5, 10 µM). WNT5A and β-catenin were also upregulated in the BaP treatment group. HESC apoptosis was restrained by BaP. Inhibiting WNT5A by SFRP5 partially restored the effect of BaP on apoptosis. In summary, these results suggested that BaP exposure during early pregnancy activates WNT5A/β-catenin signaling pathway, which inhibits the endometrial cell apoptosis and potentially destroys endometrial function.

Monitoring and Measuring Mammalian Autophagy

Macroautophagy (autophagy) is a conserved lysosomal-based intracellular degradation pathway. Here, we present different methods used for monitoring autophagy at cellular level. The methods involve Atg8/LC3 detection and quantification by Western blot, autophagic flux measurement through Western blot, direct fluorescence microscopy or indirect immunofluorescence, and finally traffic light assay using tf-LC3-II. Monitoring autophagic flux is experimentally challenging but obviously a prerequisite for the proper investigation of the process. These methods are suitable for screening purposes and can be used for measurements in cell lysates as well as in living cells. These assays have proven useful for the identification of genes and small molecules that regulate autophagy in mammalian cells.