The phosphatidylinositol 3-kinase inhibitors wortmannin and LY294002 inhibit autophagy in isolated rat hepatocytes

Eur J Biochem. 1997 Jan 15;243(1-2):240-6. doi: 10.1111/j.1432-1033.1997.0240a.x.

Abstract

Recent studies indicate that phosphatidylinositol 3-kinase is essential in the regulation of many processes dependent on membrane flow. Autophagy is a complex pathway in which cell material, including proteins, can be degraded. Membrane flow plays a pivotal role in this process. To find out whether phosphatidylinositol 3-kinase is also required for autophagy, we tested the effects on autophagy of two structurally unrelated phosphatidylinositol 3-kinase inhibitors, wortmannin and 2-(4-morpholinyl)-8-phenylchromone (LY294002). The addition of low concentrations of each of these inhibitors to incubations of hepatocytes in the absence of amino acids resulted in a strong inhibition of proteolysis. The antiproteolytic effect of wortmannin (IC50 30 nM) and LY294002 (IC50 10 microM) was accompanied by inhibition of autophagic sequestration and not by an increase in lysosomal pH or a decrease in intracellular ATP. No further inhibition of proteolysis by the two compounds was observed when autophagy was already maximally inhibited by high concentrations of amino acids. 3-Methyladenine, which is commonly used as a specific inhibitor of autophagic sequestration, was an inhibitor of phosphatidylinositol 3-kinase, thus providing a target for its action. It is proposed that phosphatidylinositol 3-kinase activity is required for autophagy. 3-Methyladenine inhibits autophagy by inhibition of this enzyme.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adenine / analogs & derivatives
  • Adenine / pharmacology
  • Androstadienes / pharmacology*
  • Animals
  • Autophagy / drug effects*
  • Cell Membrane / physiology
  • Cells, Cultured
  • Chromones / pharmacology*
  • Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / metabolism
  • Enzyme Inhibitors / pharmacology*
  • Liver / cytology*
  • Male
  • Morpholines / pharmacology*
  • Phosphatidylinositol 3-Kinases
  • Phosphorylation
  • Phosphotransferases (Alcohol Group Acceptor) / antagonists & inhibitors*
  • Protein-Serine-Threonine Kinases / metabolism
  • Rats
  • Rats, Wistar
  • Ribosomal Protein S6
  • Ribosomal Protein S6 Kinases
  • Ribosomal Proteins / metabolism
  • Signal Transduction
  • Starvation / physiopathology
  • Wortmannin

Substances

  • Androstadienes
  • Chromones
  • Enzyme Inhibitors
  • Morpholines
  • Ribosomal Protein S6
  • Ribosomal Proteins
  • 2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one
  • 3-methyladenine
  • Phosphatidylinositol 3-Kinases
  • Phosphotransferases (Alcohol Group Acceptor)
  • Protein-Serine-Threonine Kinases
  • Ribosomal Protein S6 Kinases
  • Dipeptidyl-Peptidases and Tripeptidyl-Peptidases
  • dipeptidyl peptidase II
  • Adenine
  • Wortmannin