Effect and mechanism of silent information regulator 6 on gluconeogenesis in chronic-on-acute liver failure

Abstract

Objective To investigate the effect and mechanism of silent information regulator 6 (SIRT6) and gluconeogenesis-dependent rate-limiting enzymes in hepatocytes in oxidative stress injury rats and chronic-on-acute (sub-acute) liver failure (ACLF) patients. Methods From August 2016 to May 2018, 10 patients with ACLF from Beijing Youan Hospital Affiliated to Capital Medical University were included in the ACLF group, and 10 normal donors were included in the normal control group. Level of fasting blood glucose, total bilirubin, albumin, and alanine aminotransferase (ALT) were studied. Sprague Dawley rat hepatocytes were isolated and divided into control group (without any intervention), model group (H2O2 intervention for 6 h), mammalian rapamycin target protein (mTOR) activation group (mTOR activation was added to the model group), mTOR inhibition group (mTOR inhibitor was added on the basis of the model group). Protein electrophoresis and polymerase chain reaction was used to detect the relative expression of glucose-6-phosphatase (G6P), phosphoenolpyruvate (PEPCK), SIRT6, and mTOR. Results The ALT and total bilirubin level in ACLF group were significantly higher than those in the normal control group, and the differences were statistically significant (all P<0.05). In ACLF group, level of SIRT6 (0.15±0.07) μg/L and fasting blood glucose (3.19±0.59) mmol/L were significantly lower than those in the normal control group (0.46±0.15) μg/L and (7.07±2.07) mmol/L, the difference was statistically significant (all P<0.05). The relative expression of PEPCK and G6P protein in liver tissue of ACLF group was significantly lower than that of normal control group. The relative expression of SIRT6, PEPCK, and G6P in the model group were lower than those in the control group, and the differences were statistically significant (all P<0.05). When mTOR is activated, the relative expression of PEPCK, G6P, and SIRT6 was higher than those in the model group, and after mTOR inhibition, the relative expression of PEPCK, G6P, and SIRT6 was lower than in the model group. Conclusion ACLF, SIRT6 may inhibit gluconeogenesis, and increased the occurrence of hypoglycemia through activating mTOR signaling pathway. Blocking of SIRT6 levels may slow down the progress of ACLF. Key words: Acute-on-chronic liver failure; Glucose-6-phosphatase; Phosphoenolpyruvate carboxykinase; Silent information regulator 6; Mammalian rapamycin target protein