Induction of dolichyl-saccharide intermediate biosynthesis corresponds to increased long chain cis-isoprenyltransferase activity during the mitogenic response in mouse B cells

• Published in: The Journal of biological chemistry 1994-04, Vol.269 (14), p.10559-10565
• Main Authors: CRICK, D. C, SCOCCA, J. R, RUSH, J. S, FRANK, D. W, KRAG, S. S, WAECHTER, C. J
• Format: Article
• Language: English
• Subjects: Alkyl and Aryl Transferases; Analytical, structural and metabolic biochemistry; Animals; B-Lymphocytes - cytology; B-Lymphocytes - drug effects; B-Lymphocytes - metabolism; Base Sequence; Biological and medical sciences; Carbohydrate Sequence; Carbohydrates; Cell Differentiation - genetics; Cells, Cultured; DNA Primers; Enzyme Induction; Female; Fundamental and applied biological sciences. Psychology; Heterosides; Hydroxymethylglutaryl CoA Reductases - metabolism; Lipopolysaccharides - pharmacology; Lymphocyte Activation; Mice; Mice, Inbred DBA; Mitogens - pharmacology; Molecular Sequence Data; Other biological molecules; Phosphoric Monoester Hydrolases - metabolism; Phosphotransferases (Alcohol Group Acceptor) - metabolism; Polyisoprenyl Phosphate Sugars - metabolism; Transferases - biosynthesis; Transferases - metabolism
• ISSN: 0021-9258; 1083-351X
• DOI: 10.1016/S0021-9258(17)34096-6

There are large increases in the rates of Glc3-Man9GlcNAc2-P-P-Dol (Oligo-P-P-Dol) biosynthesis and protein N-glycosylation during the proliferative response of murine B lymphocytes (B cells) to bacterial lipopolysaccharide (LPS). To learn more about the regulation of dolichyl-saccharide biosynthesis, the possible relationships between developmental changes in specific steps in dolichyl phosphate (Dol-P) and N-acetyl-glucosaminylpyrophosphoryldolichol (GlcNAc-P-P-Dol) biosynthesis and the induction of Oligo-P-P-Dol biosynthesis were investigated. These studies describe an impressive induction of long chain cis-isoprenyltransferase (cis-IPTase) activity, an enzyme system required for the chain elongation stage in de novo Dol-P synthesis, which corresponded to the striking increase in the rate of Oligo-P-P-Dol biosynthesis in LPS-activated B cells. The cellular level and specific activity of cis-IPTase increase 15-fold in LPS-treated cells with relatively unaltered affinity for isopentenyl pyrophosphate. The rates of Dol-P and Oligo-P-P-Dol synthesis increased substantially when cis-IPTase activity was induced, suggesting a regulatory relationship between the level of cis-IPTase activity and lipid intermediate synthesis. Distinctly different developmental patterns were observed for cis-IPTase and HMG-CoA reductase activity, and when sterol biosynthesis was drastically inhibited by lovastatin, the rate of synthesis of Dol-P was slightly higher in the presence of the drug. Modest elevations in the cellular levels of dolichol kinase, Dol-P phosphatase, and UDP-GlcNAc:Dol-P N-acetylglucosaminylphosphoryltransferase (L-G1PT) activities were also observed, but these changes were relatively small compared with the increases in cis-IPTase activity and the rates of Dol-P, Gl-cNAc-P-P-Dol, and Oligo-P-P-Dol synthesis. The expression of the L-G1PT gene is an early event in the developmental program for Oligo-P-P-Dol synthesis, but GlcNAc-P-P-Dol formation is apparently not rate-limiting. In summary, large increases in cis-IPTase activity and the rate of Dol-P biosynthesis appear to play a key regulatory role in the induction of Oligo-P-P-Dol biosynthesis during the proliferative response of B cells to LPS, and the biosynthetic pathways for Dol-P and cholesterol are regulated independently in dividing B cells.