Calcium ionophore A23187 induction of spermidine/spermine N1-acetyltransferase activity in bovine lymphocytes.

The divalent cation ionophore A23187 increased the activity in bovine lymphocytes of spermidine/spermine N1-acetyltransferase, a rate-limiting enzyme in polyamine biodegradation. The enzyme was induced in a dose- and time-dependent manner. Induction was suppressed by indomethacin, but not by trifluoperazine (TFP), N-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide (W-7) or palmitoylcarnitine. These results suggest that the activation of phospholipase A2 involves the induction of spermidine/spermine N1-acetyltransferase. Ornithine decarboxylase, a rate-limiting enzyme in polyamine biosynthesis, was not suppressed by indomethacin but was by TFP and W-7. The molecular mechanism of the induction of spermidine/spermine N1-acetyltransferase and ornithine decarboxylase may be different.