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

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.

• Authors: K Mori, Y Wada, J Mimuro, M Matsuda, Y Yoshikuni, K Kimura, Y Sakata
• Journal: Biochimica et biophysica acta (Biochim Biophys Acta) Vol. 1226 Issue 3 Pg. 300-6 (Jul 18 1994) ISSN: 0006-3002 [Print] Netherlands
• PMID: 8054362 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)

Chemical References

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

Topics

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