Phoenixin-14 Ameliorates Cellular Senescence Against Morphine in M17 Neuronal Cells.

Drug dependence on morphine is commonly accompanied by neurodegenerative disorders. A previous study showed that prolonged exposure to morphine induces cellular senescence in neuronal cells by reducing telomere length. Phoenixin-14 is a newly discovered brain peptide with pleiotropic roles. However, it is unknown whether phoenixin-14 possesses a beneficial property against morphine-induced cellular senescence. Our results show that morphine reduced the expression of G protein-coupled receptor 173 (GPR173) in M17 neuronal cells. Therefore, we speculated that phoenixin-14, as a ligand for GPR173, may be involved in the morphine-mediated response in M17 cells. Further, we found that phoenixin-14 mitigated morphine-induced oxidative stress by reducing the reactive oxygen species (ROS) production and increasing superoxide dismutase (SOD) activity in M17 neuronal cells. The morphine-induced cellular senescence in M17 neuronal cells was prevented by phoenixin-14. Phoenixin-14 resolved the morphine-caused cell cycle arrest with significant changes in the expression levels of p21, cyclin-dependent kinases 6 (CDK6), and p-Rb. It also elevated the telomerase activity and restored the expressions of human telomerase reverse transcriptase (hTERT) and TERF2 in morphine-induced M17 neuronal cells. Furthermore, phoenixin-14 restored the yes-associated protein (YAP) expression against morphine in M17 neuronal cells. Knockdown of YAP abolished the beneficial effects of phoenixin-14 on cellular senescence against morphine induction. Taken together, these aggregate data demonstrate that phoenixin-14 prevented cellular senescence against morphine induction in M17 neuronal cells via regulating YAP expression.