title: Degranulation in RBL-2H3 cells: regulation by calmodulin pathway.
abstract: Involvement of the calmodulin pathway in Ca2+-induced degranulation was evaluated in RBL-2H3 mast cells. Pretreatment of RBL-2H3 cells with a calmodulin antagonist, W-13, blocked ionomycin-dependent release of beta-hexosaminidase into the supernatant, although W-13 treatment alone slightly but significantly increased the release. Ca2+/calmodulin activates various protein kinases and phosphatases including myosin-light chain kinase (MLCK), calmodulin-dependent protein kinases (CaMKs), and calcineurin. When RBL-2H3 cells were pretreated with a MLCK inhibitor, ML-7, or a CaMKs inhibitor, KN-93, the ionomycin-dependent release of beta-hexosaminidase into the supernatant was inhibited. In addition, pretreatment with calcineurin inhibitors, cyclosporin A and FR901725, resulted in blockage of the ionomycin-dependent release of beta-hexosaminidase into the supernatant. Our results indicate that Ca2+/calmodulin, activated calmodulin, is indispensable for Ca2+-induced degranulation, and that within the calmodulin pathways, at least MLCK, CaMKs and calcineurin positively regulate the release of granules initiated by increasing cytosolic Ca2+ concentrations in RBL-2H3 cells.
mesh_terms: D000818:Animals; D001381:Azepines / Q000494:pharmacology; D019703:Calcineurin / Q000378:metabolism; D002118:Calcium / Q000378:metabolism; D017871:Calcium-Calmodulin-Dependent Protein Kinases / Q000378:metabolism; D002147:Calmodulin / Q000378:metabolism*; D015550:Cell Degranulation; D002460:Cell Line; D045744:Cell Line, Tumor; D016572:Cyclosporine / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005786:Gene Expression Regulation; D015759:Ionomycin / Q000494:pharmacology; D015471:Leukemia, Basophilic, Acute / Q000473:pathology; D009219:Myosin-Light-Chain Kinase / Q000378:metabolism; D009281:Naphthalenes / Q000494:pharmacology; D010456:Peptides, Cyclic / Q000494:pharmacology; D051381:Rats; D013449:Sulfonamides / Q000494:pharmacology; D013997:Time Factors; D001619:beta-N-Acetylhexosaminidases / Q000378:metabolism
chemical_list: D001381:Azepines; D002147:Calmodulin; D009281:Naphthalenes; D010456:Peptides, Cyclic; D013449:Sulfonamides; C070571:ML 7; D015759:Ionomycin; C033772:N-(4-aminobutyl)-5-chloro-2-naphthalenesulfonamide; D016572:Cyclosporine; D017871:Calcium-Calmodulin-Dependent Protein Kinases; D009219:Myosin-Light-Chain Kinase; D019703:Calcineurin; D001619:beta-N-Acetylhexosaminidases; D002118:Calcium