Diacylglycerol triggers Rim101 pathway–dependent necrosis in yeast: a model for lipotoxicity

a Schematic illustration of the pathways that lead to DG accumulation in the dga1？ lro1？ DKO and dga1？ lro1？ dgk1？ TKO strains: DG is either transformed into triacylglycerol (TG) by acylation with activated fatty acids (acyl-CoA) or acyl-residues derived from phospholipids through Dga1 or Lro1, respectively, or may be phosphorylated to phosphatidic acid (PA) by the action of Dgk1. The DKO (dga1？ lro1？) mutant is defective for TG formation and therefore accumulates DG. The additional knock out of DGK1 encoding DG kinase, in the TKO strain further increases DG accumulation. Administration of choline directly drains DG into phosphatidylcholine (PC) through the Kennedy pathway and thus facilitates growth of the TKO mutant. b–d Mass spectrometry-assisted quantification of lipids from total yeast cell extracts harvested 12？h after inoculation: total DG (b), DG species (c), and total TG (d). The numbers on the x axis of c indicate the cumulative number of carbon atoms (first number) and the number of double bonds in both acyl-chains (second number after the colon) e Thin layer chromatography performed with the same lipid extracts as were used for MS analysis. Comparison to the standard allows to differentiate between sn-1,3 and sn-1,2 DG species. SE steryl esters, S sterols, PL phospholipids. Statistical significance was assessed using one-way ANOVA for b and d and T-Test for c. Error bars indicate SEM and asterisks in the figures indicate significant differences, *p？<？0.05, **p？<？0.01, ***p？<？0.001, ****p？<？0.000