Cytokine secretion requires phosphatidylcholine synthesis

J Cell Biol. 2008 Jun 16;181(6):945-57. doi: 10.1083/jcb.200706152.

Abstract

Choline cytidylyltransferase (CCT) is the rate-limiting enzyme in the phosphatidylcholine biosynthetic pathway. Here, we demonstrate that CCT alpha-mediated phosphatidylcholine synthesis is required to maintain normal Golgi structure and function as well as cytokine secretion from the Golgi complex. CCT alpha is localized to the trans-Golgi region and its expression is increased in lipopolysaccharide (LPS)-stimulated wild-type macrophages. Although LPS triggers transient reorganization of Golgi morphology in wild-type macrophages, similar structural alterations persist in CCT alpha-deficient cells. Pro-tumor necrosis factor alpha and interleukin-6 remain lodged in the secretory compartment of CCT alpha-deficient macrophages after LPS stimulation. However, the lysosomal-mediated secretion pathways for interleukin-1 beta secretion and constitutive apolipoprotein E secretion are unaltered. Exogenous lysophosphatidylcholine restores LPS-stimulated secretion from CCT alpha-deficient cells, and elevated diacylglycerol levels alone do not impede secretion of pro-tumor necrosis factor alpha or interleukin-6. These results identify CCT alpha as a key component in membrane biogenesis during LPS-stimulated cytokine secretion from the Golgi complex.

Publication types

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

MeSH terms

  • Animals
  • Bacterial Infections / metabolism
  • Biomarkers / metabolism
  • Cytokines / metabolism*
  • Diglycerides / biosynthesis
  • Golgi Apparatus / drug effects
  • Golgi Apparatus / metabolism
  • Interleukin-6 / metabolism
  • Lipopolysaccharides / pharmacology
  • Macrophages / cytology
  • Macrophages / enzymology
  • Macrophages / metabolism
  • Macrophages / microbiology
  • Mice
  • Models, Biological
  • Nucleotidyltransferases / deficiency
  • Phosphatidylcholines / biosynthesis*
  • Protein Processing, Post-Translational / drug effects
  • Sphingomyelins / biosynthesis
  • Tumor Necrosis Factor-alpha / metabolism

Substances

  • Biomarkers
  • Cytokines
  • Diglycerides
  • Interleukin-6
  • Lipopolysaccharides
  • Phosphatidylcholines
  • Sphingomyelins
  • Tumor Necrosis Factor-alpha
  • Nucleotidyltransferases