Phosphatidylinositol-5-phosphate 4-kinases regulate cellular lipid metabolism by facilitating autophagy
By Mark Lundquist, M. Goncalves, Ryan M. Loughran, Elite Possik, Tarika Vijayaraghavan, A. Yang, C. Pauli, Archna Ravi, A. Verma, Zhiwei Yang and 13 more. 2018
95 citations recorded by the source corpus.
Summary While the majority of phosphatidylinositol-4, 5-bisphosphate (PI-4, 5-P2) in mammalian cells is generated by the conversion of phosphatidylinositol-4-phosphate (PI-4-P) to PI-4, 5-P2, a small fraction can be made by phosphorylating phosphatidylinositol-5-phosphate (PI-5-P). The physiological relevance of this second pathway is not clear. Here, we show that deletion of the genes encoding the two most active enzymes in this pathway, Pip4k2a and Pip4k2b, in the liver of mice causes a large enrichment in lipid droplets and in autophagic vesicles during fasting. These changes are due to a defect in the clearance of autophagosomes, which halts autophagy and reduces the supply of nutrients salvaged through this pathway. Similar defects in autophagy are seen in nutrient-starved Pip4k2a−/−Pip4k2b−/− mouse embryonic fibroblasts and in C. elegans lacking the PI5P4K ortholog. These results suggest that this alternative pathway for PI-4, 5-P2 synthesis evolved, in part, to enhance the ability of multicellular organisms to survive starvation.
Subfields: Cell Biology, Epidemiology, Pharmacology
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Citations in the corpus
- Targeting the PI5P4K lipid kinase family in cancer using covalent inhibitors (2020, background): “Recently, PI5P4K was demonstrated to be necessary for the proper completion of autophagy in mouse models (Lundquist et al., 2018).”