Cyclic AMP‐like effects of polyamines on phosphatidylcholine synthesis and protein phosphorylation in human promyelocytic leukemia HL60 cells

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Abstract
Spermine or putrescine increased cAMP levels through a catalase‐sensitive mechanism, resulting in, most notably, a dephosphorylation of protein A (M r 45 000, pI 5.15) and protein B (M r 45000, pI 4.9) and slightly increased phosphatidylcholine (PC) synthesis in HL60 cells. Exogenous dibutyryl cAMP mimicked the polyamine effects. 12‐O‐Tetradecanoyl phorbol‐13‐acetate (TPA) also promoted the protein dephosphorylation and PC synthesis, the effects augmented by R59022 and mimicked by exogenous 1‐oleoyl‐2‐acetylglycerol. The effects of spermine (or dibutyryl cAMP) and TPA on PC synthesis were synergistic. It was suggested that cAMP‐dependent protein kinase and protein kinase C might mediate, in an independent but interrelated manner, the effects of polyamines and TPA.