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Increase in cellular triacylglycerol content and emergence of large ER-associated lipid droplets in the absence of CDP-DG synthase function.

He Y, Yam C, Pomraning K, Chin JS, Yew JY, Freitag M, Oliferenko S - Mol. Biol. Cell (2014)

Bottom Line: Understanding what determines the cellular amount of neutral lipids and their packaging into lipid droplets is of fundamental and applied interest.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.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.

View Article: PubMed Central - PubMed

Affiliation: Temasek Life Sciences Laboratory, 117604 Singapore Department of Biological Sciences, National University of Singapore, 117543 Singapore.

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S. japonicus bbl1 mutant cells accumulate triacylglycerols. (A) LDs in bbl1 mutant cells are considerably larger than that in the wild type at the restrictive temperature of 36°C. Scale bar, 5 μm. (B) TLC shows that bbl1 mutant cells contain higher amounts of triacylglycerols than the wild type (WT) at both permissive (24°C) and restrictive temperatures (36°C). (C) Mass spectrometry analysis of the triacylglycerol content in WT (blue) and bbl1 (red) mutant cells is consistent with TLC data. Error bars, SDs (n = 5). (A–C) Cells grown in rich yeast extract–based medium.
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Figure 2: S. japonicus bbl1 mutant cells accumulate triacylglycerols. (A) LDs in bbl1 mutant cells are considerably larger than that in the wild type at the restrictive temperature of 36°C. Scale bar, 5 μm. (B) TLC shows that bbl1 mutant cells contain higher amounts of triacylglycerols than the wild type (WT) at both permissive (24°C) and restrictive temperatures (36°C). (C) Mass spectrometry analysis of the triacylglycerol content in WT (blue) and bbl1 (red) mutant cells is consistent with TLC data. Error bars, SDs (n = 5). (A–C) Cells grown in rich yeast extract–based medium.

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.


Increase in cellular triacylglycerol content and emergence of large ER-associated lipid droplets in the absence of CDP-DG synthase function.

He Y, Yam C, Pomraning K, Chin JS, Yew JY, Freitag M, Oliferenko S - Mol. Biol. Cell (2014)

S. japonicus bbl1 mutant cells accumulate triacylglycerols. (A) LDs in bbl1 mutant cells are considerably larger than that in the wild type at the restrictive temperature of 36°C. Scale bar, 5 μm. (B) TLC shows that bbl1 mutant cells contain higher amounts of triacylglycerols than the wild type (WT) at both permissive (24°C) and restrictive temperatures (36°C). (C) Mass spectrometry analysis of the triacylglycerol content in WT (blue) and bbl1 (red) mutant cells is consistent with TLC data. Error bars, SDs (n = 5). (A–C) Cells grown in rich yeast extract–based medium.
© Copyright Policy - creative-commons
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4263451&req=5

Figure 2: S. japonicus bbl1 mutant cells accumulate triacylglycerols. (A) LDs in bbl1 mutant cells are considerably larger than that in the wild type at the restrictive temperature of 36°C. Scale bar, 5 μm. (B) TLC shows that bbl1 mutant cells contain higher amounts of triacylglycerols than the wild type (WT) at both permissive (24°C) and restrictive temperatures (36°C). (C) Mass spectrometry analysis of the triacylglycerol content in WT (blue) and bbl1 (red) mutant cells is consistent with TLC data. Error bars, SDs (n = 5). (A–C) Cells grown in rich yeast extract–based medium.
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.

Bottom Line: Understanding what determines the cellular amount of neutral lipids and their packaging into lipid droplets is of fundamental and applied interest.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.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.

View Article: PubMed Central - PubMed

Affiliation: Temasek Life Sciences Laboratory, 117604 Singapore Department of Biological Sciences, National University of Singapore, 117543 Singapore.

Show MeSH