title: Cell cycle-related expression of poly(ADP-ribosyl)transferase in proliferating rat thymocytes.
abstract: The activity profile of poly(ADP-ribosyl)transferase was assayed during a complete cell cycle of rat thymocytes stimulated in the presence of interleukin-2 by concanavalin A or monoclonal antibodies against the T-cell antigen receptor (TCRmAB). Poly ADP-ribosylation was measured in permeabilized cells by the incorporation of [adenine-3H]NAD+ into protein bound poly ADP-ribose. The polymers of ADP-ribose were separated from the monomers using dihydroxyboronyl-Bio-Rex 70 columns. The rate of poly(ADP-ribosyl)ation increases during the G1 phase with a maximum 12 h after stimulation. This increase in activity is due to enhanced de novo synthesis of poly(ADP-ribosyl)transferase which can be abolished by the addition of cycloheximide. The half-life of this enzyme during the induction period was estimated to be 4 h. A second activity peak appears during the S-phase of the cell cycle 48 h after stimulation. The maxima of the poly(ADP-ribosyl)ation rate coincide with elevated immunoreactive enzyme levels at 12 and 48 h of culture assayed by Western blotting. The mRNA levels of pADPRT do not correlate with the first maximum of activity, whereas the second maximum was accompanied by a 5-fold increase of the specific mRNA. These results suggest a translational regulation of pADPRT in the G1 phase of the cell cycle, whereas the second activity peak in the S-phase is due to an increased transcription and translation. The induction of pADPRT activity in the G1 phase of TCRmAB-stimulated cells points to a function of poly(ADP-ribosyl)ation in the proliferation of thymocytes.
authors.affiliation: Institute of Biochemistry, Faculty of Medicine, University of Erlangen-Nürnberg, Germany.
authors.forename: K H
authors.initials: KH
authors.lastname: Wein
authors.forename: R
authors.initials: R
authors.lastname: Netzker
authors.forename: K
authors.initials: K
authors.lastname: Brand
mesh_terms: D000246:Adenosine Diphosphate Ribose / Q000302:isolation & purification; D000818:Animals; D002453:Cell Cycle; D002455:Cell Division; D002478:Cells, Cultured; D003208:Concanavalin A; D004072:Digitonin; D005260:Female; D007376:Interleukin-2; D011065:Poly(ADP-ribose) Polymerases / Q000235:genetics / Q000378:metabolism*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017208:Rats, Wistar; D013936:Thymidine / Q000378:metabolism; D013950:Thymus Gland / Q000201:enzymology*; D013997:Time Factors
chemical_list: D007376:Interleukin-2; D012333:RNA, Messenger; D003208:Concanavalin A; D000246:Adenosine Diphosphate Ribose; D011065:Poly(ADP-ribose) Polymerases; D004072:Digitonin; D013936:Thymidine