Increase in cellular triacylglycerol content and emergence of large ER-associated lipid droplets in the absence of CDP-DG synthase function.
Bottom Line: Using two species of fission yeast, we show that cycling cells deficient in the function of the ER-resident CDP-DG synthase Cds1 exhibit markedly increased triacylglycerol content and assemble large lipid droplets closely associated with the ER membranes.We demonstrate that these unusual structures recruit the triacylglycerol synthesis machinery and grow by expansion rather than by fusion.Our results suggest that interfering with the CDP-DG route of phosphatidic acid utilization rewires cellular metabolism to adopt a triacylglycerol-rich lifestyle reliant on the Kennedy pathway.
Affiliation: Temasek Life Sciences Laboratory, 117604 Singapore Department of Biological Sciences, National University of Singapore, 117543 Singapore.Show MeSH
Mentions: We did not observe large neutral lipid deposits surrounded by the ER in bbl1 cells at 24°C, although the BODIPY 493/503–stained LDs exhibited some degree of clustering (Figure 2A). Thin-layer chromatography (TLC) analysis indicated that the amount of TGs was higher in bbl1 cells than in the wild-type control even at 24°C but increased further after shifting to 36°C (Figure 2B). Direct measurements of the TG content by mass spectrometry showed an approximately twofold increase in the amount of the entire spectrum of TGs but not sterol esters in bbl1 cells as compared with the control (Figure 2C and Supplemental Figure S2). On the basis of these observations, we concluded that bbl1 mutant cells exhibited a considerable increase in TG abundance and abnormal LD morphology.
Affiliation: Temasek Life Sciences Laboratory, 117604 Singapore Department of Biological Sciences, National University of Singapore, 117543 Singapore.