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Activin A (Act A), a member of the transforming growth factor-beta (TGF-β), reduces neuronal apoptosis during cerebral ischemia through Act A/Smads signaling pathway. However, little is known about the effect of Act A/Smads pathway on autophagy in neurons. Here, we found that oxygen-glucose deprivation (OGD)-induced autophagy was suppressed by exogenous Act A in a concentration-dependent manner and enhanced by Act A/Smads pathway inhibitor (ActRIIA-Ab) in neuronal PC12 cells. These results indicate that Act A/Smads pathway negatively regulates autophagy in OGD-treated PC12 cells. In addition, we found that c-Jun N-terminal kinase (JNK) and p38 mitogen-activated protein (MAP) kinase pathways are involved in the OGD-induced autophagy. The activation of JNK and p38 MAPK pathways in OGD-treated PC12 cells was suppressed by exogenous Act A and enhanced by ActRIIA-Ab. Together, our results suggest that Act A/Smads signaling pathway negatively regulates OGD-induced autophagy via suppression of JNK and p38 MAPK pathways in neuronal PC12 cells. [ABSTRACT FROM AUTHOR]

Dysregulation of autophagy in endothelial cells plays a vital role in cardiovascular dysfunction and atherosclerosis. Accumulating evidence shows that miRNAs regulate autophagy in various cell types by targeting autophagy-related genes. In the present study, we found that a co-culture of human umbilical vein endothelial cells (HUVECs) with human aortic smooth muscle cells (HAoSMCs) inhibited autophagy activity in HUVECs. Furthermore, we isolated exosomes secreted by HAoSMCs, and confirmed that the exosomes contain miR-221/222. We investigated the role of miR-221/222 transferred by HAoSMC-derived exosomes in HUVECs. These exosomes induced an increase of miR-221/222 expression and a down-regulation of phosphatase and tensin homolog deleted on chromosome ten (PTEN) in HUVECs. Dual luciferase reporter assays revealed that miR-221/222 could bind to the 3′UTR of PTEN, which implied that PTEN was a direct target of miR-221/222. The expression of PTEN could be down-regulated by miR-221/222 over-expression. Then, we detected the expression of PTEN, LC3, ATG5, SQSTM1/p62, Beclin-1, Akt, and phospho-Akt in HUVECs transfected with miR-221/222 mimics and inhibitors. Our results demonstrated that miR-221/222 overexpression inhibited the expression of PTEN and subsequently activated Akt signaling, and eventually down-regulated the expression of LC3II, ATG5 and Beclin-1, and elevated the expression of SQSTM1/p62. This phenomenon can be reversed by the transfection of miR-221/222 inhibitors. These data suggested that miR-221/222 from HAoSMC-derived exosomes inhibited autophagy in HUVECs by modulating PTEN/Akt signaling pathway. [ABSTRACT FROM AUTHOR]