Phorbol ester treatment of HL 60 leukemia cells results in increase of beta-(1 -> 4)-galactosyltransferase

We previously showed that HL 60 leukemia cells exhibit various changes in t heir cellular glycans after phorbol la-myristate 13-acetate (PMA) treatment . These changes could originate largely from changes in one or several glyc osyltransferases. In this report, we show using enzymatic measures, fluores cence microscopy, immunoblotting and Northern blot that beta-(1 --> 4)-gala ctosyltransferase I (GalT I) activity was higher (> x 2) in PMA-treated com pared with untreated HL 60 cells. Immunoblotting showed an increased intens ity of the GalT I band at 49 kDa and Northern blot a weak increase of the G alT I transcript band, after PMA treatment. Moreover, Northern blot perform ed after actinomycin-D treatment of the cells, which inhibits transcription , suggests that the observed increase of GalT I expression could originate, in part, from increase of the stability of GalT I transcripts. (C) 2000 El sevier Science Ltd. All rights reserved.