Lipoprotein lipase activity/mass ratio is higher in omental than in subcutaneous adipose tissue

Abstract

Lipoprotein lipase (LPL) is important for lipid deposition in adipose tissue (AT) and responds rapidly to changes in the nutritional state. Animal experiments indicate that short-term regulation of LPL is mainly post-translational. Different processing of LPL in different AT depots may play a role in the distribution of lipids in the body. Lipoprotein lipase mRNA, mass and activity were measured in pieces of omental adipose tissue (OAT) and subcutaneous adipose tissue (SAT) from 15 subjects undergoing gastrointestinal surgery (four male and 11 female subjects, mean age 54 +/- 5 years, BMI 28 +/- 2 kg m(-2)). Lipoprotein lipase activity was higher in OAT than in SAT (18 +/- 2.1 compared with 12 +/- 1.6 mU g(-1), P < 0.01), whereas LPL mass was lower in OAT than in SAT (100 +/- 9 compared with 137 +/- 16 mU g(-1), P < 0.05). Consequently, the specific LPL activity (ratio of activity over mass) was approximately twofold greater in OAT compared with SAT. There was correlation between LPL mRNA and LPL activity in SAT (P < 0.05) and a similar tendency in OAT (P = 0.08). There were strong correlations (P < 0.01) for mRNA abundance as well as for LPL activity between the two depots. In contrast there was no correlation between the LPL mass and LPL mRNA or activity in any of the depots. These results indicate that long-term regulation, as reflected in the mRNA abundance, is similar in the two types of adipose tissue. The displayed activity reflects the mRNA abundance and the fraction of newly synthesized LPL molecules which the post-translational mechanism allows to become/remain active. This fraction was on average twofold greater in OAT compared with SAT.