FEBS letters
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In the search for a functional role of cytoskeletal proteins in the mechanism(s) of stimulus-secretion coupling, we have previously demonstrated that the actomyosin system might be involved in the transport of cations across the plasma membrane of bovine adrenal chromaffin cells [(1986) J. Biol. Chem. 261, 5745-5750]. ⋯ F-Actin-destabilizing agents, such as cytochalasin D or DNase 1, were found to promote Ca2+-stimulated (as well as basal) secretion. By contrast, stabilizers, like phalloidin, produced the opposite effect. It is concluded that stimulus-secretion coupling in chromaffin cells might require the reorganization of actin for modulating both ion transport across the plasma membrane and exocytotic secretion per se.
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The existence of a 15(S)-hydroxy-5,6-oxido-7,9,13-trans-11-cis-eicosatetraenoic acid intermediate in the biosynthesis of lipoxins A and B has recently been proposed. In the present study, human leukocytes were exposed to 15-HETE and the divalent cation ionophore A23187 and alcohol trapping studies were performed. The products containing alkyltetraenes were isolated and characterized. ⋯ To gain further evidence for the role of 5(6)-epoxytetraene intermediate in the biosynthesis of lipoxins, (15)-hydroxy-5,6-oxido-7,9,13-trans-11-cis-eicosatetraenoic acid was prepared by total chemical synthesis. When added to purified human liver cytosolic epoxide hydrolase, the epoxide was rapidly and quantitatively converted into LXA. The results provide further evidence for the role of a 5(6)epoxytetraene intermediate in the biosynthesis of lipoxins.