Replacement of Retinyl Esters by Polyunsaturated Triacylglycerol Species in Lipid Droplets of Hepatic Stellate Cells during Activation
Figure 7
Incorporation of exogenous arachidonic acid into TAG is increased in activated HSCs.
A. Overview of the omega-6 fatty acid synthesis pathway. B. Analysis of deuterated 18:2 and 20:4 incorporation in several TAG-PUFA species. Freshly isolated HSCs were incubated for seven days with 25 µM 18:2-d4 or 25 µM 20:4-d8. After neutral lipid extraction, HPLC-MS was performed as described. Values are expressed relative to the level of the respective undeuturated TAG species present at day 7. The results represent the means ± SEM of three experiments. C, D. Freshly isolated HSCs were incubated at day 0, 3 or 6 with 25 µM 20:4-d8 for 24 h. Subsequently, neutral lipids were extracted and HPLC-APCI-MS analysis was performed. C. Contour plots of HPLC-APCI-MS analysis of HSC at day 0 and 7 in the m/z 880–1050 region. Positions of unlabeled species are indicated with a straight line and relative position of species with one or two d8-labeled acyl chains are indicated by dotted lines. Arrowheads indicate TAG species with three d8-labeled acyl chains. D. Quantification of several TAG species containing d8-labeled acyl chains during HSC activation. The results represent the means ± SEM of three experiments.