Defining the subcellular distribution and metabolic channeling of phosphatidylinositol

J Cell Biol. 2020 Mar 2;219(3):e201906130. doi: 10.1083/jcb.201906130.

Abstract

Phosphatidylinositol (PI) is an essential structural component of eukaryotic membranes that also serves as the common precursor for polyphosphoinositide (PPIn) lipids. Despite the recognized importance of PPIn species for signal transduction and membrane homeostasis, there is still a limited understanding of the relationship between PI availability and the turnover of subcellular PPIn pools. To address these shortcomings, we established a molecular toolbox for investigations of PI distribution within intact cells by exploiting the properties of a bacterial enzyme, PI-specific PLC (PI-PLC). Using these tools, we find a minor presence of PI in membranes of the ER, as well as a general enrichment within the cytosolic leaflets of the Golgi complex, peroxisomes, and outer mitochondrial membrane, but only detect very low steady-state levels of PI within the plasma membrane (PM) and endosomes. Kinetic studies also demonstrate the requirement for sustained PI supply from the ER for the maintenance of monophosphorylated PPIn species within the PM, Golgi complex, and endosomal compartments.

Publication types

  • Comparative Study
  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism
  • Biosensing Techniques
  • COS Cells
  • Cell Membrane / metabolism*
  • Chlorocebus aethiops
  • HEK293 Cells
  • Humans
  • Intracellular Membranes / metabolism*
  • Kinetics
  • Luminescent Proteins / genetics
  • Luminescent Proteins / metabolism
  • Microscopy, Confocal
  • Phosphatidylinositol Phosphates / metabolism*
  • Phosphatidylinositols / metabolism*
  • Recombinant Fusion Proteins / genetics
  • Recombinant Fusion Proteins / metabolism
  • Second Messenger Systems
  • Type C Phospholipases / genetics
  • Type C Phospholipases / metabolism

Substances

  • Bacterial Proteins
  • Luminescent Proteins
  • Phosphatidylinositol Phosphates
  • Phosphatidylinositols
  • Recombinant Fusion Proteins
  • Type C Phospholipases