Acyl-CoA:diacylglycerol acyltransferases (DGATs) catalyze the last step in 
triglyceride (TG) synthesis. The genes for two DGAT enzymes, DGAT1 and DGAT2, 
have been identified. To examine the roles of liver DGAT1 and DGAT2 in TG 
synthesis and very low density lipoprotein (VLDL) secretion, liver DGAT1- and 
DGAT2-overexpressing mice were created by adenovirus-mediated gene transfection. 
DGAT1-overexpressing mice had markedly increased DGAT activity in the presence 
of the permeabilizing agent alamethicin. This suggests that DGAT1 possesses 
latent DGAT activity on the lumen of the endoplasmic reticulum. 
DGAT1-overexpressing mice showed increased VLDL secretion, resulting in 
increased gonadal (epididymal or parametrial) fat mass but not subcutaneous fat 
mass. The VLDL-mediated increase in gonadal fat mass might be due to the 4-fold 
greater expression of the VLDL receptor protein in gonadal fat than in 
subcutaneous fat. DGAT2-overexpressing mice had increased liver TG content, but 
VLDL secretion was not affected. These results indicate that DGAT1 but not DGAT2 
has a role in VLDL synthesis and that increased plasma VLDL concentrations may 
promote obesity, whereas increased DGAT2 activity has a role in steatosis.