Betaine Promotes LKB1-AMPK Activation Inhibits UVB-Mediated Senescence of Human Epidermal Keratinocytes Through Autophagy Induction

Betaine demonstrations antioxidative activity, enhances organic osmolytic activity and is an important cofactor in methylation. However, the main mechanisms betaine-induced autophagy in human dermal skin cells are not yet completely understood. Therefore, we hypothesized that betaine induces of autophagy. Thus, the autophagic effects exerted by betaine through activation of LKB1-AMPK signaling in human dermal fibroblasts (HDFs) and human epidermal keratinocytes (HEKs) were assessed. Betaine enhanced LKB1 and AMPK phosphorylation in HEKs, and LKB1, AMPK induced autophagy through mTOR downregulation. Beatine-induced autophagy was inhibited in cells transiently transfected with AMPK siRNA. Increased autophagosome activity was confirmed by LC3B-II formation and by increased perinuclear LC3B-II puncta in betaine-treated HEKs. according to our in vitro findings, and in vivo studies in HR-1 hairless mice demonstrated that betaine treatment significantly reduced the activity of the senescence-associated marker β-galactosidase (SA-β-gal) and increased p-LKB1 and p-AMPK levels compared with UVB-irradiated skin tissues. Collectively, our findings suggest that betaine-dependent autophagy diminishes mouse skin senescence and betaine may reduce HEK senescence through an LKB1-AMPK-dependent mechanism.