Upregulation and stabilization of senescence marker protein-30 by epigallocatechin gallate against tert-butyl hydroperoxide-induced liver injury in vitro and in vivo.

Senescence marker protein-30 (SMP30), a novel ageing marker, suppresses oxidative stress in the liver. However, studies on phytochemical-mediated regulation of SMP30 expression are lacking. Here, we showed that epigallocatechin gallate (EGCg), a polyphenol abundant in green tea, positively regulates SMP30 expression in the rat hepatoma-derived Fao cells. EGCg maintained SMP30 expression even in the presence of cycloheximide, a protein synthesis inhibitor. Furthermore, treatment of cells with tert-butyl hydroperoxide (tert-BHP), an oxidative promoter, decreased SMP30 expression and ERK1/2 phosphorylation, while EGCg treatment inhibited these effects. Male mice (7-week-old) were divided into 4 groups-Control (saline), tert-BHP (1.5 mmol/kg tert-BHP), EGCg + tert-BHP (30 mg/kg/day of EGCg and 1.5 mmol/kg tert-BHP), and EGCg (30 mg/kg/day). After oral EGCg administration for 6 consecutive days, EGCg + tert-BHP group mice were administered tert-BHP. The tert-BHP-administered mice showed decreased SMP30 expression in the liver and increased aspartate aminotransferase and alanine transaminase (hepatic injury marker enzymes) activities; however, EGCg treatment attenuated these changes. Thus, EGCg-induced SMP30 upregulation may alleviate tert-BHP-induced liver injury. The findings of this study offer new perspectives of the anti-ageing properties of EGCg.

Resveratrol Upregulates Senescence Marker Protein 30 by Activating AMPK/Sirt1-Foxo1 Signals and Attenuating H2O2-Induced Damage in FAO Rat Liver Cells.

Resveratrol (RSV) is a polyphenol with numerous biological functions, including anti-inflammatory, antioxidant, and anti-aging activities. The novel senescence marker protein-30 (SMP30) indicates aging, and it suppresses hepatic oxidative stress. However, the effects of RSV on SMP30 expression regulation remain unclear. We observed that RSV positively regulates SMP30 expression in rat hepatoma-derived FAO cells. However, this was abolished by Compound C and EX-527 that specifically inhibit AMP-activated protein kinase (AMPK) and Silent Information Regulator T1 (Sirt1), respectively. We predicted binding sites for AMPK, forkhead box protein O1 (Foxo1), and Sirt1 downstream molecules as possible SMP30 promoters using the JASPAR and UniProtKB databases. We identified a Foxo1 binding site in the promoter region of SMP30. Inhibiting Foxo1 with AS1842527 also decreased the RSV-induced upregulation of SMP30 expression. Moreover, RSV suppressed the substantial downregulation of SMP30 expression caused by oxidative stress and hydrogen peroxide (H2O2) and released accumulated lactate dehydrogenase. These results demonstrate that, as a novel food factor, RSV-induced upregulation of SMP30 by activating AMPK/Sirt1-Foxo1 signaling and may attenuates H2O2-induced oxidative damage. The findings of this study offer new perspectives of the anti-ageing properties of RSV.

Release of SMP30 in Extracellular Vesicles under Conditions of Ascorbic Acid Deficiency Is Involved with Acute Phase Response in ODS Rat.

Senescence marker protein-30 (SMP30) is a senescence marker molecule that exhibits lactonase activity in the ascorbic acid (AsA) biosynthesis pathway, except in primate mammals, including humans. Although numerous studies have shown that hepatic AsA deficiency causes acute-phase responses, details of the relationship between SMP30 expression and acute-phase responses in AsA-deficient conditions remain to be elucidated. Here, we investigated the effects of AsA deficiency on the relationship between SMP30 and acute liver injury in osteogenic disorder Shionogi (ODS) rats, which have a hereditary defect in AsA biosynthesis. Male-ODS rats (4 wk old) were pair-fed an AsA-free diet with distilled or 0.1% AsA-dissolved water for 14 d. Under AsA-deficient conditions, hepatic SMP30 protein level was decreased and liver injury markers, the serum aspartate aminotransferase/alanine transaminase ratio and cytokine-induced neutrophil chemoattractant-1 (CINC-1) concentration, were elevated. In contrast, SMP30 protein level in extracellular vesicles (EVs) was significantly increased in addition to the positive acute proteins haptoglobin and asialoglycoprotein receptor 1 (ASGPR1), hepatic-derived specific markers expression under AsA-deficient conditions. AsA deficiency also activated signal transducer and activator of transcription 3 (STAT3) which is linked to EVs release in the liver. These results suggest that the release of SMP30 in EVs by AsA deficiency is involved with acute-phase responses.