Effect of glycosidase inhibitors on the biosynthesis of alpha 2-plasmin inhibitor and antithrombin III in Hep G2 cells

Biochim Biophys Acta. 1994 Jul 18;1226(3):300-6. doi: 10.1016/0925-4439(94)90041-8.

Abstract

We studied the effect of the glucosidase I inhibitor, N-methyl-1-deoxynojirimycin (MdN) and the mannosidase inhibitor, 1-deoxymannojirimycin (dMM) on the biosynthesis and secretion of alpha 2-plasmin inhibitor (alpha 2-PI) and antithrombin III (ATIII) in cultures of human hepatoma (Hep-G2) cells. Incubation with 1 mM MdN decreased secreted alpha 2-PI activity and antigen levels by about 40%, whereas those of ATIII were not affected. Neither inhibitor affected the messenger RNA levels as determined by Northern blotting. Pulse-chase studies using [35S]-methionine showed that MdN decreased alpha 2-PI and ATIII secretion rates. By the 18 h chase, MdN had decreased secreted alpha 2-PI to 50-60%, with little effect on ATIII. Intracellular forms of alpha 2-PI or ATIII synthesized by cells treated with 1 mM MdN were sensitive to endoglycosidase H (Endo H), whereas almost all the secreted forms were resistant, suggesting the presence of complex-type oligosaccharides. In the presence of 1 mM dMM, cells synthesized Endo H-sensitive alpha 2-PI and ATIII with similar secretion rates. These results suggest that retention of glucose on N-linked oligosaccharides not only retards the exit of alpha 2-PI and ATIII, but also changes the catabolic rate of alpha 2-PI in the endoplasmic reticulum.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 1-Deoxynojirimycin / analogs & derivatives*
  • 1-Deoxynojirimycin / pharmacology*
  • Animals
  • Antithrombin III / biosynthesis*
  • Dogs
  • Glycoside Hydrolases / antagonists & inhibitors*
  • Glycoside Hydrolases / genetics
  • Hexosaminidases
  • Humans
  • Mannosidases / antagonists & inhibitors
  • Mannosidases / genetics
  • Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase
  • RNA, Messenger / analysis
  • Tumor Cells, Cultured / metabolism
  • alpha-2-Antiplasmin / biosynthesis*

Substances

  • RNA, Messenger
  • alpha-2-Antiplasmin
  • 1-Deoxynojirimycin
  • Antithrombin III
  • Glycoside Hydrolases
  • Hexosaminidases
  • Mannosidases
  • Mannosyl-Glycoprotein Endo-beta-N-Acetylglucosaminidase
  • N-methyldeoxynojirimycin