text: Adipose tissue as a source of nicotinamide N-methyltransferase and homocysteine.
  Nicotinamide N-methyltransferase (NNMT) catalyses the conversion of nicotinamide to 1-methylnicotinamide and plays an important role in hepatic detoxification reactions. Here we show that, in addition to the liver, 3T3-L1 adipocytes as well as human and murine adipose tissue explants express high amounts of enzymatically active NNMT. NNMT mRNA levels and enzyme activity increased in 3T3-L1 cells in a differentiation-dependent manner. Homocysteine, the atherogenic product of the NNMT-catalyzed reaction, was secreted from 3T3-L1 cells or adipose tissue cultures. Homocysteine release increased during 3T3-L1 differentiation and was reduced when adipose tissue was treated with the NNMT inhibitor 1-methylnicotinamide. Nicotinic acid (NA), a widely used drug to lower elevated plasma lipid levels, induced NNMT enzyme activity in white adipose tissue of mice. In tissue culture nicotinamide treatment led to an increase in adipose tissue homocysteine secretion. These data support the concept that adipose tissue NNMT contributes to the increased plasma homocysteine levels in patients treated with NA.
entities.id: T10 T11 T12 T13 T14 T15 T16 T17 T18 T19 T1 T20 T21 T22 T23 T24 T25 T2 T3 T4 T5 T6 T7 T8 T9
entities.type: CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL GENE-Y GENE-Y GENE-Y CHEMICAL GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y GENE-Y CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL CHEMICAL
entities.text: NA 1-methylnicotinamide nicotinamide homocysteine nicotinamide N homocysteine Nicotinamide N-methyltransferase NNMT NNMT Nicotinamide NNMT NNMT NNMT NNMT NNMT nicotinamide N-methyltransferase homocysteine NA N Homocysteine Homocysteine nicotinamide 1-methylnicotinamide Nicotinic acid