title: Regulation of two isozymes of prostaglandin endoperoxide synthase and thromboxane synthase in human monoblastoid cell line U937.
abstract: The mechanism responsible for the rapid increase of thromboxane A2 synthesis by cells of the human monoblastoid cell line U937, which were differentiated with 12-O-tetradecanoyl-phorbol-13-acetate, induced by lipopolysaccharide (LPS) was studied. Both RNA blot and immunoblot analyses showed that LPS increased the levels of prostaglandin endoperoxide synthase-1 (PES-1) and -2 (PES-2) in a time-dependent manner, and the modes of induction of the two isozymes differed. The maximum PES-1 mRNA level was 1.6 times higher 36 h after than before stimulation by LPS, and that of PES-2 mRNA was elevated about 20-fold at its peak at 12 h after stimulation. Consequently, the immunoreactive PES-1 and PES-2 protein levels also increased time-dependently after LPS stimulation. However, the effects of LPS on the thromboxane synthase mRNA and protein levels were much less marked. These results indicate that LPS-induced thromboxane synthesis by the differentiated cells was regulated at the levels of the two PES isozymes, predominantly at the PES-2 level.
mesh_terms: D001095:Arachidonic Acids / Q000378:metabolism; D002454:Cell Differentiation; D002460:Cell Line; D004790:Enzyme Induction; D004926:Escherichia coli; D015971:Gene Expression Regulation, Enzymologic; D006801:Humans; D015151:Immunoblotting; D007527:Isoenzymes / Q000096:biosynthesis*; D007700:Kinetics; D008070:Lipopolysaccharides / Q000494:pharmacology; D008861:Microsomes / Q000201:enzymology; D011451:Prostaglandin-Endoperoxide Synthases / Q000096:biosynthesis*; D012333:RNA, Messenger / Q000032:analysis / Q000096:biosynthesis; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology; D013930:Thromboxane-A Synthase / Q000096:biosynthesis*; D013997:Time Factors; D014407:Tumor Cells, Cultured
chemical_list: D001095:Arachidonic Acids; D007527:Isoenzymes; D008070:Lipopolysaccharides; D012333:RNA, Messenger; D011451:Prostaglandin-Endoperoxide Synthases; D013930:Thromboxane-A Synthase; D013755:Tetradecanoylphorbol Acetate