Mesenchymal stem cells enhance autophagy of human intrahepatic biliary epithelial cells in vitro

Exosomal cargos modulate autophagy in recipient cells via different signaling pathways

Vesicular system of mammalian cells is composed of two intracellular and extracellular vesicles systems, which contributes to the intra/intercellular communication and cellular homeostasis. These systems mediate transferring of biological molecules like proteins, nucleic acids, and lipids inside the cytoplasm, and between the cells. By the present study, authors describe molecular crosslink between exosome biogenesis and autophagy and take a certain focus on the autophagic cargos of exosomes and signaling pathways involved in exosome-induced autophagy in target cells and vice versa. Autophagy the generation of double-phospholipid vesicles, is a process that engulfs damaged proteins and organelles, share molecular similarity and function synergy with exosomes biogenesis for degradation or exocytosis of certain cargo. Exosomes, the smallest subtype of extracellular vesicles, originating from the membrane of the multivesicular body located inside cells demonstrate key roles in the intracellular and intercellular communication. Growing evidence demonstrates the interaction between exosome biogenesis and autophagy both at intertwined molecular pathways and crossbred vesicles known as amphisomes. Crosstalk between exosome biogenesis and autophagy contributes to maintain cellular homeostasis under external and internal stresses. Moreover, these processes can modulate each other via different signaling pathways. Exosomes contain autophagic cargos that induce autophagy via the cascade of molecular events in target cells, which called here exosome-induced autophagy. Taken together, crosstalk between exosome biogenesis and autophagy plays pivotal roles in cell homeostasis. Shedding light on the interaction between endomembrane systems may promote our knowledge about the relation between exosome and autophagy pathways in lysosome-related disorders against treatments; proposing a theoretical approach for therapy.

Ligustilide protects PC12 cells from oxygen-glucose deprivation/reoxygenation-induced apoptosis via the LKB1-AMPK-mTOR signaling pathway

Autophagy has been shown to have a protective effect against brain damage. Ligustilide (LIG) is a bioactive substance isolated from Ligusticum chuanxiong, a traditional Chinese medicine. LIG has a neuroprotective effect; however, it is unclear whether this neuroprotective effect involves autophagy. In this study, PC12 cells were treated with 1 × 10^–5–1 × 10^–9 M LIG for 0, 3, 12 or 24 hours, and cell proliferation was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assay. Treatment with 1 × 10^–6 M LIG for 3 hours had the greatest effect on cell proliferation, and was therefore used for subsequent experiments. PC12 cells were pre-treated with 1 × 10^–6 M LIG for 3 hours, cultured in 95% N₂/5% CO₂ in Dulbecco’s modified Eagle’s medium without glucose or serum for 4 hours, and then cultured normally for 16 hours, to simulate oxygen-glucose deprivation/reoxygenation (OGD/R). Cell proliferation was assessed with the MTS assay. Apoptosis was detected by flow cytometry. The expression levels of apoptosis-related proteins, Bcl-2 and Bax, autophagy-related proteins, Beclin 1 and microtubule-associated protein l light chain 3B (LC3-II), and liver kinase B1 (LKB1)-5′-adenosine monophosphate-activated protein kinase (AMPK)-mammalian target of rapamycin (mTOR) signaling pathway-related proteins were assessed by western blot assay. Immunofluorescence staining was used to detect LC3-II expression. Autophagosome formation was observed by electron microscopy. LIG significantly decreased apoptosis, increased Bcl-2, Beclin 1 and LC3-II expression, decreased Bax expression, increased LC3-II immunoreactivity and the number of autophagosomes, and activated the LKB1-AMPK-mTOR signaling pathway in PC12 cells exposed to OGD/R. The addition of the autophagy inhibitor 3-methyladenine or dorsomorphin before OGD/R attenuated the activation of the LKB1-AMPK-mTOR signaling pathway in cells treated with LIG. Taken together, our findings show that LIG promotes autophagy and protects PC12 cells from apoptosis induced by OGD/R via the LKB1-AMPK-mTOR signaling pathway.