Sodium sulfite promotes the assembly and secretion of very low-density lipoprotein in HL-7702 hepatocytes

Abstract

This study investigated the effects of Na2SO3 on the fat metabolism in human normal diploid HL-7702 (referred as L-02) hepatocytes. After 24 h and 48 h, treatment with different concentrations of Na2SO3, the intra and extra-hepatocellular triglyceride (TG) contents of L-02 were determined using chemical-enzymatic method. The contents of very low-density lipoprotein (VLDL) and apolipoprotein B100 (apoB100) in the culture supernatants were determined using enzyme-linked immunosorbent assay (ELISA). Western blot was applied to detect the expressions of fatty acid oxidation and fat synthesis related proteins, VLDL assembly and secretion in L-02 cells. Results: Na2SO3 treatment (10 mM, 24 h/48 h) significantly increased the intra TG level in the hepatocytes. Different concentrations of Na2SO3 increased the extra-hepatocellular TG content. After 24 h exposure, the extracellular VLDL levels and secretions of apoB100 in 0.1–10 mM Na2SO3 groups were significantly higher than that of the negative control (P < 0.05). Meanwhile, the expression of CPT1 and SREBP1 protein were significantly reduced by Na2SO3. MTP and TGH protein expressions were significantly elevated in each Na2SO3 treatment group. The expression level of LDLR in hepatocytes was reduced by Na2SO3. Conclusion: Na2SO3 exposure may promote the hepatocellular VLDL assembly and secretion, through increasing of MTP and TGH expressions and inhibiting the uptake of extracelluar VLDL. Keywords: Sodium sulfite, Hepatocytes, VLDL, Fatty acid oxidation, Fat synthesis, VLDL uptake