title: Opposing changes in N-acetylglucosaminyltransferase-V and -III during the cell cycle and all-trans retinoic acid treatment of hepatocarcinoma cell line.
abstract: The changes in N-acetylglucosaminyltransferase-V and -III (GnT-V, GnT-III) during the cell-cycle of synchronized 7721 human hepatocarcinoma cell line were investigated. Using an HPLC method to assay GnT and flow cytometry (FCM) for cell cycle analysis, it was found that GnT-V showed the highest activity, but GnT-III reached the lowest activity when G(2)/M cells were most abundant. In contrast, GnT-V declined to the minimum while GnT-III elevated to maximum when G(0)/G(1) cells were most predominant. The opposing changes were more obvious when the activities of GnT-V and GnT-III were expressed as relative activities (activity of GnT-V or GnT-III/the sum of activities of GnT-V plus GnT-IV plus GnT-III). These opposing changes of GnT-V and GnT-III during the cell cycle might result from the different regulatory mechanisms of GnT-V and GnT-III expression in the cell cycle. The alterations in the structures of cell surface N-glycans were compatible with the changes of the activities of GnTs. The results from immunocytochemistry and Northern blot showed that the protein and mRNA contents of GnT-V were not significantly changed during the cell cycle. The activity of a cell cycle regulating protein kinase, p34(cdc2) kinase, correlated to the activity of GnT-V. These findings suggested that the change of GnT-V activity in cell cycle was not the consequence of the alteration of gene transcription or enzyme protein synthesis, but might be caused by the post-translational regulation. The decrease in GnT-V and the corresponding increase in GnT-III activities were also found after the cells were treated with all-trans retinoic acid (ATRA), and the mechanism of this might be different from that in the cell cycle.
authors.affiliation: Key Laboratory of Glycoconjugate Research, Ministry of Health, Department of Biochemistry, Shanghai Medical University, Shanghai, PR China.
authors.forename: H B
authors.initials: HB
authors.lastname: Guo
authors.forename: A L
authors.initials: AL
authors.lastname: Jiang
authors.forename: T Z
authors.initials: TZ
authors.lastname: Ju
authors.forename: H L
authors.initials: HL
authors.lastname: Chen
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology; D006528:Carcinoma, Hepatocellular / Q000473:pathology; D002453:Cell Cycle / Q000502:physiology; D018844:Cyclin-Dependent Kinases; D005434:Flow Cytometry; D016193:G1 Phase / Q000502:physiology; D016195:G2 Phase / Q000502:physiology; D006735:Horseradish Peroxidase / Q000378:metabolism; D006801:Humans; D007150:Immunohistochemistry; D037102:Lectins / Q000378:metabolism; D008938:Mitosis / Q000502:physiology; D017351:N-Acetylglucosaminyltransferases / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D016192:Resting Phase, Cell Cycle / Q000502:physiology; D014212:Tretinoin / Q000494:pharmacology*; D014407:Tumor Cells, Cultured; D000095043:Cyclin-Dependent Kinase-Activating Kinase
chemical_list: D000970:Antineoplastic Agents; D037102:Lectins; D012333:RNA, Messenger; D014212:Tretinoin; D006735:Horseradish Peroxidase; D017351:N-Acetylglucosaminyltransferases; C054599:beta-1,4-mannosyl-glycoprotein beta-1,4-N-acetylglucosaminyltransferase; C052254:alpha-1,6-mannosylglycoprotein beta 1,6-N-acetylglucosaminyltransferase; D017346:Protein Serine-Threonine Kinases; D018844:Cyclin-Dependent Kinases; D000095043:Cyclin-Dependent Kinase-Activating Kinase