DEPP/DEPP1/C10ORF10 regulates hepatic glucose and fat metabolism partly via ROS-induced FGF21.

Decidual protein induced by progesterone (DEPP/DEPP1/C10ORF10) is induced by denying access to food and reduced by refeeding in insulin-sensitive organs in vivo. The negative regulation of DEPP by insulin is also proven in several cell lines. However, the functions of DEPP in insulin-sensitive organs remain unknown. In the present study, we investigated the impact of DEPP on hepatic energy metabolism and addressed the underlying mechanisms. The metabolic effects of DEPP were investigated in mice with adenovirus-mediated hepatic overexpression. Liver triglyceride (TG), glycogen, and serum metabolites were detected by biochemical assays. Energy homeostasis was measured by indirect calorimetry. Quantitative PCR was used to examine expression of genes involved in fatty acid oxidation, ketogenesis, lipogenesis, and gluconeogenesis. To evaluate the role of fibroblast growth factor 21 (FGF21) mediating the metabolic effects of DEPP, FGF21 antibody was administrated intraperitoneally to mice at 24 h after the delivery of adenovirus, and the metabolic alterations were examined. Reactive oxygen species (ROS) levels were measured by catalase activity assay, live cell fluorescence, or quantitative PCR. Effects of DEPP on the phenotype of db/db mice were also assessed. Acute hepatic overexpression of DEPP significantly reduced serum glucose and TG levels, dramatically elevated ß-hydroxybutyrate levels, and improved glucose clearance. Compared with controls, DEPP overexpression reduced food intake, the energy expenditure rate, and the respiratory quotient. DEPP overexpression significantly increased fatty acid oxidation and ketogenesis but suppressed lipid synthesis and gluconeogenesis. Investigations of the underlying mechanisms revealed that DEPP regulates energy metabolism by inducing oxidative stress. With the impairment of the ROS scavenging system and promotion of ROS formation, DEPP overexpression leads to ROS accumulation. FGF21 is upregulated in response to oxidative stress and mediates the effects of DEPP on fatty acid oxidation, ketogenesis, and lipid synthesis but not gluconeogenesis, as evidenced by the fact that the FGF21 antibody dramatically suppressed a DEPP-induced increase of fatty acid oxidation and ketogenesis, reversed the reduction of lipid synthesis, but did not change the suppression of gluconeogenesis. Moreover, overexpression of DEPP in db/ db mice led to a marked reduction in body weight and serum glucose levels and significantly improved insulin sensitivity. Hepatic overexpression of DEPP in mice promotes fatty acid oxidation and ketogenesis and suppresses lipogenesis and gluconeogenesis, which is partly mediated by FGF21 induced by elevated cellular ROS levels.-Li, W., Ji, M., Lin, Y., Miao, Y., Chen, S., Li, H. DEPP/DEPP1/C10ORF10 regulates hepatic glucose and fat metabolism partly via ROS-induced FGF21.

Osthole prevents acetaminophen-induced liver injury in mice.

Acetaminophen (APAP) overdose leads to severe hepatotoxicity. Osthole, a natural coumarin found in traditional Chinese medicinal herbs, has therapeutic potential in the treatment of various diseases. In this study, we investigated the effects of osthole against APAP-induced hepatotoxicity in mice. Mice were administered osthole (100 mg·kg-1·d-1, ip) for 3 d, then on the fourth day APAP (300 mg/kg, ip) was co-administered with osthole. The mice were euthanized post-APAP, their serum and livers were collected for analysis. Pretreatment with osthole significantly attenuated APAP-induced hepatocyte necrosis and the increases in ALT and AST activities. Compared with the mice treated with APAP alone, osthole pretreatment significantly reduced serum MDA levels and hepatic H2O2 levels, and improved liver GSH levels and the GSSG-to-GSH ratio. Meanwhile, osthole pretreatment markedly alleviated the APAP-induced up-regulation of inflammatory cytokines in the livers, and inhibited the expression of hepatic cytochrome P450 enzymes, but it increased the expression of hepatic UDP-glucuronosyltransferases (UGTs) and sulfotransferases (SULTs). Furthermore, osthole pretreatment reversed APAP-induced reduction of hepatic cAMP levels, but pretreatment with H89, a potent selective PKA inhibitor, failed to abolish the beneficial effect of osthole, whereas pretreatment with L-buthionine sulfoximine, a GSH synthesis inhibitor, abrogated the protective effects of osthole on APAP-induced liver injury, and abolished osthole-caused alterations in APAP-metabolizing enzymes. In cultured murine primary hepatocytes and Raw264.7 cells, however, osthole (40 µmol/L) did not alleviate APAP-induced cell death, but it significantly suppressed APAP-caused elevation of inflammatory cytokines. Collectively, we have demonstrated that osthole exerts a preventive effect against APAP-induced hepatotoxicity by inhibiting the metabolic activation of APAP and enhancing its clearance through an antioxidation mechanism.

Osthole pretreatment alleviates TNBS-induced colitis in mice via both cAMP/PKA-dependent and independent pathways.

Osthole, a natural coumarin found in traditional Chinese medicinal plants, has shown multiple biological activities. In the present study, we investigated the preventive effects of osthole on inflammatory bowel disease (IBD). Colitis was induced in mice by infusing TNBS into the colonic lumen. Before TNBS treatment, the mice received osthole (100 mg·kg-1·d-1, ip) for 3 d. Pretreatment with osthole significantly ameliorated the clinical scores, colon length shortening, colonic histopathological changes and the expression of inflammatory mediators in TNBS-induced colitis. Pretreatment with osthole elevated serum cAMP levels; but treatment with the PKA inhibitor H89 (10 mg·kg-1·d-1, ip) did not abolish the beneficial effects of osthole on TNBS-induced colitis. In mouse peritoneal macrophages, pretreatment with osthole (50 µmol/L) significantly attenuated the LPS-induced elevation of cytokines at the mRNA level; inhibition of PKA completely reversed the inhibitory effects of osthole on IL-1ß, IL-6, COX2, and MCP-1 but not on TNFα. In Raw264.7 cells, the p38 inhibitor SB203580 markedly suppressed LPS-induced upregulation of the cytokines, whereas the PKA inhibitors H89 or KT5720 did not abolish the inhibitory effects of SB203580. Moreover, in LPS-stimulated mouse peritoneal macrophages, SB203580 strongly inhibited the restored expression of IL-1ß, IL-6, COX2, and MCP-1, which was achieved by abolishing the suppressive effects of osthole with the PKA inhibitors. Western blot analysis showed that osthole significantly suppressed the phosphorylation of p38, which was induced by TNBS in mice or by LPS in Raw264.7 cells. Inhibition of PKA partially reversed the suppressive effects of osthole on p38 phosphorylation in LPS-stimulated cells. Collectively, our results suggest that osthole is effective in the prevention of TNBS-induced colitis by reducing the expression of inflammatory mediators and attenuating p38 phosphorylation via both cAMP/PKA-dependent and independent pathways, among which the cAMP/PKA-independent pathway plays a major role.

Liver Regeneration Is Impaired in Mice with Acute Exposure to a Very Low Carbohydrate Diet.

BACKGROUND: The metabolic response to hepatic insufficiency has been implicated in the regulators of normal liver regeneration. Modulation of nutritional factors has been demonstrated to affect liver regeneration. Diets containing very low carbohydrate and high fat levels cause a unique metabolic state, the effect of which on liver regeneration is unknown. METHODS: Mice were placed on standard mice chow (ND) or a very low carbohydrate diet (VLCD) after 70% partial hepatectomy (PH). After 48 h, mice on VLCD were placed back to ND. The serum metabolic profiles, hepatic lipid content, and gene expression profile were examined. The dynamics of liver regeneration were detected at timed points. Activation of signaling pathways was examined. RESULTS: VLCD feeding caused hypoglycemia and elevation of serum ß-hydroxybutyrate and free fatty acids in mice after PH. It increased hepatic triglyceride contents, enhanced fatty acid oxidation, and reduced lipid synthesis. Mice on VLCD exhibited diminished hepatocellular mitotic frequency, a reduced BrdU incorporation and liver mass regeneration ratio, and delayed expression of PCNA. Expressions of IL-6 and TNFα in liver and serum were downregulated. Meanwhile, phosphorylation of STAT3, Erk, and AKT was delayed compared with controls. CONCLUSIONS: VLCD feeding delayed liver regeneration, probably because of the suppression of TNFα-IL-6-STAT3 signaling and delayed activation of Erk and AKT induced by the unique metabolic effects of this diet.