Polyamine regulation of heat-shock-induced spermidine N1-acetyltransferase activity.
The enzyme spermidine/spermine N1-acetyltransferase (N1-SAT) is rapidly induced by heat shock in CHO and A549 cells, with activity declining by 24 h. Depletion of intracellular polyamines by alpha-difluoromethylornithine, an inhibitor of ornithine decarboxylase, blocks this induction. Re-addition of putrescine to these cultures restores the response to heat shock, with a concomitant increase in intracellular N1-acetylspermidine. Diaminopropane is more than twice as effective as the naturally occurring diamine putrescine, suggesting that the propylamine moiety of spermidine is involved in the regulation of N1-SAT induction. Inhibitor studies indicate transcriptional activation and that the enzyme has an apparent half-life of 30-60 min. A second heat shock rapidly inhibits induced N1-SAT activity, which decays with a half-life of 2-3 min. Despite its induction by heat, N1-SAT is not a stable enzyme, suggesting that the activity observed is not due to a modification of an existing peptide, but is due to a transcriptional event, which may justify the inclusion of this enzyme in the family of heat-shock proteins.
Fuller
D J
DJ
University of Arizona Cancer Center, Department of Radiation Oncology, Tucson 85724.
Carper
S W
SW
Clay
L
L
Chen
J R
JR
Gerner
E W
EW
D000123:Acetyltransferases / Q000032:analysis / Q000096:biosynthesis*; D000818:Animals; D001679:Biogenic Amines / Q000502:physiology*; D002478:Cells, Cultured; D006224:Cricetinae; D003513:Cycloheximide / Q000494:pharmacology; D003609:Dactinomycin / Q000494:pharmacology; D003959:Diamines / Q000494:pharmacology; D000518:Eflornithine / Q000494:pharmacology; D004790:Enzyme Induction; D006358:Hot Temperature; D006801:Humans; D011700:Putrescine / Q000494:pharmacology; D014158:Transcription, Genetic; D000099228:Diamine N-Acetyltransferase
D000123:Acetyltransferases; D001679:Biogenic Amines; D003513:Cycloheximide; D003609:Dactinomycin; D003959:Diamines; D000518:Eflornithine; D011700:Putrescine; D000099228:Diamine N-Acetyltransferase