p53 mediates phospholipid headgroup scavenging [RNA-seq]

A growing number of studies have shown that p53 modulates metabolic pathways to support diverse biological functions. Given that p53 is most widely known to act as a transcriptional activator, this raises the possibility that p53 transcriptional activity governs metabolic reprogramming. Here, we performed targeted metabolomics and lipidomic analysis which revealed an increase in the de novo biosynthesis of phosphatidylethanolamine (PE) upon p53 activation. Elevated levels of phosphoethanolamine (PEtn), the PE headgroup, in p53 active cells are sustained through PE headgroup recycling, which is partially mediated through the transcriptional activation of autophagy by p53. Disruption of phospholipid headgroup recycling through genetic perturbation of the CDP-ethanolamine pathway results in defects in cell-state specific perturbations in growth and gene expression. Notably, we observe restructuring of endoplasmic reticulum (ER)-mitochondria contacts in cells where headgroup recycling was abrogated, likely an attempt to maintain lipid homeostasis, and this reorganization is reversed when flux through the CDP-Etn pathway is restored. Together, these results suggest that lipid recycling to be an additional tool in the p53 arsenal supporting cellular fitness. Overall design: KPnull cells engineered to express a doxycycline-inducible vector without cDNA (Vector) or various forms of p53 (WT, wild-type; TAD1m, TAD1 p53 mutant; TAD2m, TAD2 p53 mutant; TAD1/2m, TAD1/2 p53 mutant) cultured with or without doxycycline for two days. KPsh cells grown on or off doxycycline for ten days. Cells were collected in duplicate or triplicate, followed by total RNA extraction using TRIzol.