VLDL Hydrolysis by Hepatic Lipase Regulates PPARδ Transcriptional Responses
Figure 5
Global metabolite profiling identifies specific unsaturated FAs generated by HL hydrolysis of VLDL that activate PPAR transcriptional responses.
(A) Left Panel. Negative ionization mode LC/MS analysis of lipid extracts from HL/VLDL treatment group demonstrated significant increases in levels of long chain fatty acids including palmitic (C16:0), palmitoleic (C16:1), oleic (C18:1), linoleic (C18:2), linolenic (C18:3), arachidonic (C20:4), eicosapentaenoic (C20:5) and docosohexaenoic (C22:6) acid. Absolute nanomoles of fatty acid were calculated using the integrated ion intensity of the internal standard C13 oleic acid. Each experimental condition was performed in triplicate, with results representing the mean +/− SD. Right Panel. The absolute fold change for each fatty acid comparing treatment with HL/VLDL vs GFP/VLDL is shown. *p<.05 vs GFP/VLDL for each fatty acid. (B) COS-7 cells were transfected with PPARδ-LBD and stimulated with the fatty acids fatty acids indicated. Results expressed as the percent of maximal LBD activation measured with PPARδ synthetic agonist GW501516. *p<.05 vs control. (C) FAO cells were treated with indicated concentrations of fatty acid in media with 1% BSA, BSA control or the PPARδ synthetic agonist GW501516 at maximal concentration. Following stimulation RNA was harvested and ADRP expression analyzed by RT-PCR. Results expressed as relative copy number in arbitrary units. *p<.05 vs BSA and control. **p<.05 vs vehicle.