THE EXPRESSION AND FUNCTION OF IPLA2B IN B-CELLS

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This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Many cells express a Group VIA phospholipase A2, designated iPLA2B, that does not require calcium for activation, is stimulated by ATP, and is sensitive to inhibition by a bromoenol lactone suicide substrate (BEL). Studies in various cell systems have led to the suggestion that iPLA2B has a role in phospholipids remodeling, signal transduction, cell proliferation, and apoptosis. We have found that pancreatic islets, B-cells, and glucose-responsive insulinoma cells express an iPLA2B that participates in glucose-stimulated insulin secretion but is not involved in membrane phospholipids remodeling. Additionally, recent studies reveal that iPLA2B is involved in pathways that contribute to B-cell proliferation and apaptosis, and that various phospholipid-derived mediators are involved in these processes. Detailed characterization of the enzyme suggests that the B-cells express multiple isoforms of iPLA2B, and we hypothesize that these participate in different cellular functions.