title: Phospholipases stimulate secretion in RBL mast cells.
abstract: Roles for glycerophospholipids in exocytosis have been proposed, but remain controversial. Phospholipases are stimulated following the activation of the high-affinity receptor for immunoglobulin E (IgE) in mast cells. To study the biochemical sequelae that lead to degranulation, broken cell systems were employed. We demonstrate that the addition of three distinct types of exogenous phospholipases (i.e., bcPLC, scPLD, and tfPLA(2)), all of which hydrolyze phosphatidylcholine (PC), trigger degranulation in permeabilized RBL-2H3 cells, a mucosal mast cell line. Production of bioactive lipids by these phospholipases promotes release of granule contents through the plasma membrane and acts downstream of PKC, PIP(2), and Rho subfamily GTPases in regulated secretion. These exogenous phospholipase-induced degranulation pathways circumvent specific factors activated following stimulation of the IgE receptor as well as in ATP- and GTP-dependent intracellular pathways. Taken together, these results suggest that regulated secretion may be achieved in vitro in the absence of cytosolic factors via phospholipase activation and that products of PC hydrolysis can promote exocytosis in mast cells.
authors.affiliation: Department of Molecular Medicine, Veterinary Medical Center, and Field of Biochemistry, Molecular and Cellular Biology, Cornell University, Ithaca, New York 14853-6401, USA.
authors.forename: J S
authors.initials: JS
authors.lastname: Cohen
authors.forename: H A
authors.initials: HA
authors.lastname: Brown
mesh_terms: D000818:Animals; D001409:Bacillus cereus / Q000201:enzymology; D001426:Bacterial Proteins; D001427:Bacterial Toxins / Q000494:pharmacology; D001692:Biological Transport; D015550:Cell Degranulation / Q000187:drug effects; D002462:Cell Membrane / Q000276:immunology / Q000378:metabolism; D016360:Clostridioides difficile / Q000502:physiology; D003594:Cytoplasmic Granules / Q000201:enzymology / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D007150:Immunohistochemistry; D015471:Leukemia, Basophilic, Acute / Q000201:enzymology / Q000378:metabolism; D008407:Mast Cells / Q000201:enzymology* / Q000378:metabolism*; D008565:Membrane Proteins / Q000276:immunology / Q000378:metabolism; D009281:Naphthalenes / Q000494:pharmacology; D009355:Neomycin / Q000494:pharmacology; D010739:Phospholipase D / Q000037:antagonists & inhibitors / Q000378:metabolism*; D051381:Rats; D013302:Streptomyces / Q000201:enzymology; D014407:Tumor Cells, Cultured / Q000201:enzymology / Q000378:metabolism; D010738:Type C Phospholipases / Q000037:antagonists & inhibitors / Q000378:metabolism*
chemical_list: D001426:Bacterial Proteins; D001427:Bacterial Toxins; D004791:Enzyme Inhibitors; D008565:Membrane Proteins; D009281:Naphthalenes; C031815:toxB protein, Clostridium difficile; D010738:Type C Phospholipases; D010739:Phospholipase D; D009355:Neomycin; C058819:calphostin C