Lotus germ extract rejuvenates aging fibroblasts via restoration of disrupted proteostasis by the induction of autophagy

Cell aging attenuates cellular functions, resulting in time-dependent disruption of cellular homeostasis, which maintains the functions of proteins and organelles. Mitochondria are important organelles responsible for cellular energy production and various metabolic processes, and their dysfunction is strongly related to the progression of cellular aging. Here we demonstrate that disruption of proteostasis attenuates mitochondrial function before the induction of DNA damage signaling by proliferative and replicative cellular aging. We found that lotus (Nelumbo nucifera Gaertn.) germ extract clears abnormal proteins and agglutinates via autophagy-mediated restoration of mitochondrial function and cellular aging phenotypes. Pharmacological analyses revealed that DAPK1 expression was suppressed in aging cells, and lotus germ extract upregulated DAPK1 expression by stimulating the acetylation of histones and then induced autophagy by activating the DAPK1-Beclin1 signaling pathway. Furthermore, treatment of aging fibroblasts with lotus germ extract stimulated collagen production and increased contractile ability in three-dimensional cell culture. Thus, time-dependent accumulation of abnormal proteins and agglutinates suppressed mitochondrial function in cells in the early stage of aging, and reactivation of mitochondrial function by restoring proteostasis rejuvenated aging cells. Lotus germ extract rejuvenates aging fibroblasts via the DAPK1-Beclin1 pathway-induced autophagy to clear abnormal proteins and agglutinates.