Lipoprotein lipase is expressed in cultured Schwann cells and functions in lipid synthesis and utilization

Abstract

We have previously demonstrated that lipoprotein lipase (LPL; triacylglycero-protein acylhydrolase, EC 3.1.1.34) is most likely expressed in the non-neuronal cells of the spinal cord, and glial cells may thus be the site of expression in the peripheral nervous system as well. We investigated the expression of LPL in cultured 1.17 cells, an immortalized rat sciatic nerve Schwann cell line. The 1.17 cells were shown to express LPL mRNA by reverse transcriptase-polymerase chain reaction analysis. The 1.17 Schwann cells demonstrated heparin-releasable lipolytic activity that was inhibited by the lipase inhibitor tetrahydrolipstatin in a dose-dependent manner. Preincubation of 1.17 cells with an antirat LPL antiserum reduced the heparin-releasable lipolytic activity to 80“% at 2 and 6 h after addition of the radiolabeled substrate. At 24 h, radioactivity in diacylglycerol and cholesteryl esters was similar in cells treated with anti-LPL antiserum or preimmune serum, whereas 14C incorporation into polar lipids was still reduced by >60”%. Separation of the polar lipids into individual lipid species revealed no specific changes in triolein-derived radioactivity incorporation across the phospholipid species examined. These results suggest that LPL-mediated hydrolysis of exogenous triacylglycerol is an important source of free fatty acids for the Schwann cell and thus may play a critical role in myelin biosynthesis in the peripheral nervous system. —Huey, P. U., T. Marcell, G. C. Owens, J. Etienne, and R. H. Eckel. Lipoprotein lipase is expressed in cultured Schwann cells and functions in lipid synthesis and utilization. J. Lipid. Res. 1998. 39: 2135–2142.

Keywords

• myelin
• phospholipids
• triacylglycerol
• peripheral nerve
• lipolysis