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: Similar to the cds1bbl1 mutant in S. japonicus, cds1-9 S. pombe cells formed large LDs associated with the ER membranes upon shift to the restrictive temperature of 36°C (Figure 6A). In the rich yeast extract–based medium, the average droplet volume dramatically increased, whereas the number of droplets decreased (Figure 6B; number of LDs per cell at 36°C was 23 ± 4 and 6 ± 2 for the wild type and cds1-9 mutant, respectively). Of note, we observed higher number of LDs when cells were grown in minimal medium (number of LDs per cell at 36°C was 34 ± 5 and 29 ± 7 for the wild type and cds1-9 mutant, respectively). Of interest, the overall abundance of TG in both wild-type and cds1-9 cells also strongly depended on growth conditions, with cells grown in the rich yeast extract medium showing considerably higher TG content (Supplemental Figure S6A).
Affiliation: Temasek Life Sciences Laboratory, 117604 Singapore Department of Biological Sciences, National University of Singapore, 117543 Singapore.