[Intervention study to inhibit the glucose metabolic remodeling in hepatocytes induced by high-selenium in vitro].

Objective: To observe the effect of exogenous serine or glycine on the synthesis of selenoprotein and endogenous serine and the expression of metabolic enzymes in hepatocytes cultured with high-selenium in vitro and its dose-response relationship.

Methods: The experiment was divided into two parts, namely a inhibition experiment and a dose-response experiment, using L02 cells as the intervention target. In the inhibition experiment, the blank control group, high-Se(SeMet) group, serine intervention group and high-Se+serine intervention group were set up. Both SeMet and serine were given at a level of 0.05 μmol/L, and the blank control group was given the same volumes of saline. In the dose-response experiment, the concentration of SeMet was 0.05 μmol/L, and the intervention concentration gradients of serine or glycine were 0, 0.05, 0.1, 0.5, 1, 5, 10, 50, 100 and 500 μmol/L. The expression of phosphoglycerate dehydrogenase(PHGDH)、serine hydroxymethyltransferase 1(SHMT1)、methylenetetrahydrofolate reductase(MTHFR)、selenoprotein P(SELENOP) and glutathione peroxidase 1(GPX1)was detected by Western Blot(WB).

Results: (1)In the inhibition experiment, compared with the blank control group, the expression of selenium proteins(GPX1 and SELENOP) in L02 cells of the other three groups were significantly increased(P<0.05). Compared with the high expression of PHGDH in L02 cells of high-Se group, the expressions of PHGDH, SHMT1 and MTHFR in high-Se + serine group were significantly decreased(P<0.05). (2) In the dose-response experiment, the expression of PHGDH enzyme in L02 cells gradually decreased with the increase of the concentration of exogenous serine or glycine, showing an obvious dose-dependent effect. In contrast, none of the other metabolic enzymes(SHMT1 and MTHFR) showed similar trends in protein expression.

Conclusion: The upregulated expression of PHGDH, the key enzyme in the de novo synthesis pathway of serine in hepatocytes cultured with high-selenium can be inhibited feedback by exogenous serine or endogenous serine transformed from exogenous glycine directly.