Hepatic PEMT activity mediates liver health, weight gain, and insulin resistance.

Phosphatidylethanolamine (PE) N-methyltransferase (PEMT) accounts for ∼30% of hepatic phosphatidylcholine (PC) biosynthesis. Pemt-/- mice fed a high-fat diet are protected against diet-induced obesity (DIO) and insulin resistance (IR) but develop nonalcoholic fatty liver disease (NAFLD) associated with a decreased PC:PE ratio. We investigated whether the lack of hepatic PEMT or the lack of PEMT in other tissues (where it is expressed at low levels) is responsible for or contributes to the protection against DIO and IR in Pemt-/- mice. Furthermore, we investigated whether decreasing PEMT expression with antisense oligonucleotides (ASOs) would result in metabolic benefits in both lean and obese mice without negatively impacting liver health. We both restored hepatic PEMT in Pemt-/- mice via adeno-associated virus delivery and decreased hepatic PEMT with ASOs in wild-type and ob/ob mice. Weight gain, insulin sensitivity, and indices of liver function were determined. We report that the protection against DIO and IR and the development of NAFLD is dependent on hepatic PEMT activity. NAFLD, associated with a significant decrease in the hepatic PC:PE ratio, was exacerbated by PEMT deficiency in obese mice, suggesting that phospholipid insufficiency promotes NAFLD progression during obesity or overnutrition. Hepatic PEMT is critical for maintaining phospholipid balance, which is crucial for a healthy liver.-Wan, S., van der Veen, J. N., Bakala N'Goma, J.-C., Nelson, R. C., Vance, D. E., Jacobs, R. L. Hepatic PEMT activity mediates liver health, weight gain, and insulin resistance.