Study Of Formaldehyde On Lipid Metabolism Pathway In HepG2 Cells

Objective:To explore the influence of formaldehyde on lipid metabolism in the hepatocytes,including triglyceride metabolism related SREBP-1c-FAS pathway and cholesterol metabolism related Insig-1-SCAP-SREBPs pathway,in order to provide basis for lipid metabolic disorder in the hepatocytes caused by formaldehyde.Methods:HepG2 cells were treated with FA at 0.004,0.02,0.1,0.5,2.5 and 12.5 mmol/L concentrations,negative control(DMEM),1 mmol/L oleic acid(OA)and 2.5 ?g/m L BFA(Brefeldin A),after 24 h and 48 h treatment,cell viability was detected with MTT assay.After treatment with different concentrations of formaldehyde for 24 h and 48 h,the intra and extra-hepatocellular triglyceride(TG)content and free cholesterol(FC)were determined using chemical-enzymatic method;western blot was used to detect the expressions of TG related proteins AMP-activated protein kinase(AMPK?),Phospho-AMP-activated protein kinase(p-AMPK?),Sterol regulatory element binding protein 1c(SREBP-1c),Acetyl-Co A carboxylase(ACC1),Phospho-Acetyl-Co A carboxylase(p-ACC1),Fatty acid synthase(FASN),Sn-1,2-diacylglycerol acyltransferase(DGAT1/2),Carboxylesterase3(CES3),Adipose triglyceride lipase(ATGL)and cholesterol related proteins Sterol regulatory element binding protein 2(SREBP-2),Hydroxy mothylglutaryl coenzyme A reductase(HMGCR),Acyl coenzyme A-cholesterol acyltransferase(ACAT),Insulin induced gene 1(Insig-1),Srebp cleavage activating protein(SCAP),Low-density lipoprotein receptor(LDLR)and intracellular Very low-density lipoprotein(VLDL),Apolipoprotein B100(apo B100),Site-1 protease(S1P)and Site-2 protease(S2P)were determined using ELISA.Results:1.Formaldehyde treatment(0.5~12.5 mmol/L,24 h /48 h)significantly depressed cell viability.2.FA treatment for 24 h increased extracellular TG level in the hepatocytes.The expressions SREBP-1c,ACC1 and FASN proteins significantly increased;DGAT1 protein expressions significantly increased in 0.1 mmol/L FA group,and decreased in other groups;CES3 protein expressions significantly elevated.3.FA treatment for 48 h decreased intracellular TG level in the hepatocytes.p-AMPK? protein expressions significantly increased in 0.1 mmol/L FA treatment group;SREBP-1c,ACC1 and FASN proteins expressions were not changed significantly;DGAT1protein expressions decreased;ATGL protein expressions significantly decreased in 0.004mmol/L FA treatment group.4.After 24 h treatment,intracellular cholesterol level increased in the hepatocytes;The expressions HMGCR protein significantly increased;ACAT protein expressions significantly decreased;SREBP-2 protein expressions significantly decreased;Insig-1protein expressions significantly decreased in 0.004 mmol/L FA and increased in other groups;LDLR protein expressions significantly decreased.5.After 48 h treatment,intracellular cholesterol level increased in the hepatocytes;extracellular cholesterol level decreased in 0.004,0.02 mmol/L FA groups;The expressions of HMGCR protein significantly increased;ACAT protein expressions significantly decreased in 0.02,0.1 mmol/L FA groups;Insig-1 protein expressions significantly decreased in 0.02,0.1 mmol/L FA groups;LDLR protein expressions significantly decreased.Conclusions:1.The high levels of FA treatment could depress cell viability of hepatocytes.2.FA exposure could affect triglyceride synthesis and secretion of hepatocytes through SREBP-1c-FAS pathway.3.FA exposure could affect cholesterol metabolism of hepatocytes through Insig-1-SCAP-SREBPs pathway.