Phospholipase A2 (PLA2) enzymes catalyze the hydrolysis of the sn-2 position of glycero-phospholipids to liberate free fatty acids and lysophospholipids. More than one third of the PLA2 enzymes belong to the secreted PLA2 (sPLA2) family, which contains 11 isoforms. Individual sPLA2s exhibit unique tissue and cellular localizations and enzymatic properties, suggesting their distinct pathophysiological roles. Since sPLA2s are secreted, their target membranes should reside in the extracellular spaces. In comparison with the well-established roles of cytosolic PLA2, the biological roles of sPLA2s have remained unclear until recently. However, recent studies using transgenic and knockout mice for several sPLA2 enzymes have revealed their distinct contributions to various biological events by producing lipid mediators, by promoting membrane remodeling, by modifying extracellular non-cellular lipid components such as surfactants and lipoproteins, or by degrading foreign phospholipids such as bacterial membranes and dietary lipids. In this review, emerging biological roles of sPLA2 enzymes in pathophysiology will be discussed.
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