Differential effects of vanadate on UDP-N-acetylglucosaminyl transferase activity derived from cytosol and nucleosol

Biochem Biophys Res Commun. 2004 Jun 11;318(4):911-5. doi: 10.1016/j.bbrc.2004.04.101.

Abstract

UDP-N-acetylglucosaminyl transferase (OGT) is a key enzyme of a novel signal transduction pathway that regulates protein function through O-linked glycosylation. In the current study, we found that sodium vanadate potently inhibits OGT activity in brain cytosol (IC50 = 55 microM) and nucleosol (IC50 = 150 microM), but fails to alter activity of a related enzyme (UDP-galactosyltransferase). Vanadate also inhibits OGT activity in cytosol (IC50 of 2.3 microM) and nucleosol (IC50 of 130) derived from a stable HeLa cell line that overexpresses OGT. When HeLa cytosol was immunopurified to separate OGT from other cellular proteins, vanadate still inhibited OGT activity (IC50 = 2 microM). We conclude that OGT derived from cytosol exhibits greater vanadate sensitivity than nucleosol OGT and that a large difference exists (25-fold) in vanadate sensitivity when comparing OGT activity in different cell types (IC50 of 55 microM for brain cytosol vs. 2.3 microM for HeLa cytosol). Understanding the mechanism(s) by which a tyrosine phosphatase inhibitor differentially reduces OGT activity should lead to new insights into OGT function and regulation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Brain / enzymology
  • Cell Nucleus / enzymology*
  • Cytosol / enzymology*
  • Enzyme Inhibitors / pharmacology
  • Galactosyltransferases / metabolism
  • HeLa Cells
  • Humans
  • N-Acetylglucosaminyltransferases / antagonists & inhibitors*
  • N-Acetylglucosaminyltransferases / genetics
  • N-Acetylglucosaminyltransferases / metabolism
  • Rats
  • Recombinant Proteins / antagonists & inhibitors
  • Recombinant Proteins / genetics
  • Recombinant Proteins / metabolism
  • Uridine Diphosphate N-Acetylglucosamine / metabolism
  • Vanadates / pharmacology*

Substances

  • Enzyme Inhibitors
  • Recombinant Proteins
  • Vanadates
  • Uridine Diphosphate N-Acetylglucosamine
  • Galactosyltransferases
  • N-Acetylglucosaminyltransferases