Blocking exosomal secretion aggravates 1,4-Benzoquinone-induced mitochondrial fission activated by the AMPK/MFF/Drp1 pathway in HL-60 cells

Extracellular vesicles-derived long noncoding RNAs participated in benzene hematotoxicity by mediating apoptosis and autophagy

Benzene is a common contaminant in the workplace and wider environment, which induces hematotoxicity. Our previous study has implicated that lncRNAs mediated apoptosis and autophagy induced by benzene. Nevertheless, the roles of extracellular vesicle(EVs)-derived lncRNAs in benzene toxicity are unknown. However, the role of EVs and EVs-derived lncRNAs in benzene-induced toxicity remains unclear. In this research, we explored the function of EVs and EVs-derived lncRNAs in cell-cell communication through benzene-induced apoptosis and autophagy. Our findings demonstrated that EVs derived from 1,4-BQ-treated cells treated cells and coculture with 1,4-BQ-treated cells enhanced apoptosis and autophagy via regulating the pathways of PI3K-AKT-mTOR and chaperone-mediated autophagy. Treating with GW4869 in 1,4-BQ-treated cells significantly inhibited EV secretion, which reduced apoptosis and autophagy. Furthermore, we identified a set of differentially expressed autophagy- and apoptosis-related lncRNAs using EVs-derived lncRNA sequencing. Among them, 8 candidate lncRNAs were upregulated in EVs derived from 1,4-BQ-treated cells, as determined by lncRNA sequencing and qRT-PCR. Importantly, these lncRNAs were also increased in the serum EVs of benzene-exposed workers. 1,4-BQ-treated cells released EVs that transfer differentially expressed lncRNAs, thereby inducing apoptosis and autophagy in the recipient cells. The above results support the hypothesis that EVs-derived lncRNAs participate in intercellular communication during benzene-induced hematotoxicity and function as potential biomarkers for risk assessment of benzene-exposed workers.

Blocking exosomal secretion aggravated 1,4-benzoquinone-induced cytotoxicity

Benzene exposure inhibits the hematopoietic system and leads to the occurrence of various types of leukemia. However, the mechanism underlying the hematotoxicity of benzene is still largely unclear. Emerging evidence has shown that exosomes are involved in toxic mechanisms of benzene. To understand the effect of 1,4-benzoquinone (PBQ; an active metabolite of benzene in bone marrow) on the exosomal release characteristics and role of exosomal secretion in PBQ-induced cytotoxicity. Exosomes were isolated from PBQ-treated HL-60 cells, purified by ultracentrifugation, and verified by transmission electron microscopy, nanoparticle tracking analysis and the presence of specific biomarkers. Our results showed that PBQ increased exosomal secretion in a dose-dependent manner, reaching a peak in 3 h at 10 μM PBQ treatment and then slowly decreasing in HL-60 cells. The exosomes contained miRNAs, which have been reported to be associated with benzene exposure or benzene poisoning. In particular, mir-34a-3p and mir-34A-5p were enriched in exosomes derived from PBQ-treated cells. In addition, the inhibition of exosomal release by GW4869 (an inhibitor of exosomal release) exacerbated PBQ-induced cytotoxicity, including increased intracellular reactive oxygen species levels, decreased mitochondrial membrane potential, and increased the apoptosis rate. Our findings illustrated that exosomes secretion plays an important role in antagonizing PBQ-induced cytotoxicity and maintaining cell homeostasis.

Depletion of serum-derived exosomes aggravates heat stress-induced damage of bovine mammary epithelial cells

BACKGROUND

Exosomes are involved in intercellular communication, affecting many physiological and pathological process. The present study evaluated the effects of serum exosomes on the function of bovine mammary epithelial cells (BMECs) and milk synthesis under heat stress.

METHODS AND RESULTS

We cultured the BMECs in fetal bovine serum (FBS) or exosome-free FBS medium and examined, their viability using CCK-8 kit. The results showed that culturing the cells in an exosome-free medium decreased viability and increased the levels of reactive oxygen species. The BMECs cultured in the exosome-free medium had reduced mitochondrial membrane potential, decreased manganese superoxide dismutase activity, and disrupted mitochondrial dynamics. They exhibited apoptosis due to upregulated Drp1, Fis1, Bax and HSP70. Lastly, we observed downregulation of milk fat and lactoprotein-related genes: mTOR, PPARγ, p-mTOR and ADD1 and SREBP1, ELF5, and CSN2, respectively, after culturing the cells in an exosome-free medium. These negative effects of the exosome-free medium on the BMECs could be further reinforced under heat stress.

CONCLUSION

Our results demonstrated that exosomes from serum are critical for maintaining the normal function of BMECs.