title: n-butyrate reduces the expression of beta-galactoside alpha 2,6-sialyltransferase in Hep G2 cells.
abstract: n-Butyrate, a short chain fatty acid that is produced by colonic bacterial fermentation, is detectable in portal blood and induces differentiation in various human neoplastic cell lines. Earlier reports indicated approximately 20-fold induction in vitro by n-butyrate of the sialyltransferase that catalyzes terminal glycosylation of GM3 ganglioside in HeLa and colon cancer cells. We previously isolated a 1.3-kilobase cDNA for a human beta-galactoside alpha 2,6-sialyltransferase, for which N-linked glycoproteins are the acceptors. We report here that treatment of Hep G2 cells with 5 mM n-butyrate for 24 h reduced beta-galactoside alpha 2,6-sialyltransferase mRNA levels by approximately 90%. Reductions in mRNA level were followed by approximately 75 and approximately 90% reductions, respectively, in specific beta-galactoside alpha 2,6-sialyltransferase enzyme activity after treatment for 24 and 36 h with 5 mM n-butyrate. However, in contrast with earlier reports of enhanced ganglioside synthesis in response to n-butyrate treatment, incubation of Hep G2 cells with n-butyrate did not alter the ganglioside pattern as assessed by thin layer chromatography of lipids extracted from treated cells. Nuclear run-on reactions indicated that the rate of transcription of beta-galactoside, alpha 2,6-sialyltransferase was not altered by treatment with 5 mM n-butyrate for 24 h, but the effects of this treatment on cytoplasmic levels of beta-galactoside alpha 2,6-sialyltransferase mRNA were largely negated by co-treatment with actinomycin D or cycloheximide. Therefore, our results show that n-butyrate reduces expression of mature beta-galactoside alpha 2,6-sialyltransferase mRNA by post-transcriptional mechanisms.
authors.affiliation: Department of Veterans Affairs Medical Center, Department of Medicine, Buffalo, New York.
authors.forename: S
authors.initials: S
authors.lastname: Shah
authors.forename: P
authors.initials: P
authors.lastname: Lance
authors.forename: T J
authors.initials: TJ
authors.lastname: Smith
authors.forename: C S
authors.initials: CS
authors.lastname: Berenson
authors.forename: S A
authors.initials: SA
authors.lastname: Cohen
authors.forename: P J
authors.initials: PJ
authors.lastname: Horvath
authors.forename: J T
authors.initials: JT
authors.lastname: Lau
authors.forename: H
authors.initials: H
authors.lastname: Baumann
mesh_terms: D015703:Antigens, CD / Q000235:genetics / Q000378:metabolism*; D002087:Butyrates / Q000494:pharmacology*; D020148:Butyric Acid; D006528:Carcinoma, Hepatocellular; D002855:Chromatography, Thin Layer; D015180:Electrophoresis, Gel, Two-Dimensional; D005732:Gangliosides / Q000302:isolation & purification; D006031:Glycosylation; D006367:HeLa Cells; D006801:Humans; D012333:RNA, Messenger / Q000378:metabolism; D012799:Sialyltransferases / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured; D000094802:beta-D-Galactoside alpha 2-6-Sialyltransferase
chemical_list: D015703:Antigens, CD; D002087:Butyrates; D005732:Gangliosides; D012333:RNA, Messenger; D020148:Butyric Acid; D012799:Sialyltransferases; D000094802:beta-D-Galactoside alpha 2-6-Sialyltransferase