title: Gelsolin in complex with phosphatidylinositol 4,5-bisphosphate inhibits caspase-3 and -9 to retard apoptotic progression.
abstract: Apoptosis, or programmed cell death, occurs because of the activation of a protease cascade amplification circuit that includes the critical effector caspase-3. Previously, we identified the widely expressed actin modulatory protein gelsolin as a prominent substrate of caspase-3 and demonstrated that the N-terminal gelsolin cleavage product promotes apoptosis. Here we show that phosphatidylinositol 4,5-bisphosphate and phosphatidylinositol 3, 4-bisphosphate in pure micelles or mixed vesicles prevent caspase-3 cleavage of gelsolin. Moreover, phosphatidylinositol 4, 5-bisphosphate-gelsolin strongly inhibits caspase-3 and -9 activity through the formation of a stable phosphatidylinositol 4, 5-bisphosphate-gelsolin-caspase complex. In addition, phosphatidylinositol 4,5-bisphosphate-gelsolin prevents apoptotic progression mediated by caspase-3 in a cell-free system, and phosphatidylinositol 4,5-bisphosphate-gelsolin-caspase-9 and phosphatidylinositol 4,5-bisphosphate-gelsolin-caspase-3 complexes form in mouse embryonic fibroblasts during apoptosis induction when stimulated with fibronectin, to delay cell death. The results suggest that gelsolin can act as both an effector and an inhibitor of caspase-3, the latter in concert with phosphatidylinositol 4, 5-bisphosphate, and other membrane phospholipids to regulate the onset and progression of apoptosis.
authors.affiliation: Genetics Laboratory, Hematology Division, Brigham and Women's Hospital, Boston, Massachusetts 02115, USA.
authors.forename: T
authors.initials: T
authors.lastname: Azuma
authors.forename: K
authors.initials: K
authors.lastname: Koths
authors.forename: L
authors.initials: L
authors.lastname: Flanagan
authors.forename: D
authors.initials: D
authors.lastname: Kwiatkowski
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D053148:Caspase 3; D053453:Caspase 9; D061945:Caspase Inhibitors; D020169:Caspases / Q000378:metabolism; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005347:Fibroblasts; D018260:Gelsolin / Q000737:chemistry / Q000494:pharmacology*; D006801:Humans; D019169:Jurkat Cells; D007700:Kinetics; D008099:Liver / Q000201:enzymology; D051379:Mice; D019269:Phosphatidylinositol 4,5-Diphosphate / Q000737:chemistry / Q000494:pharmacology*; D018129:Phosphatidylinositol Phosphates / Q000494:pharmacology
chemical_list: D061945:Caspase Inhibitors; D004791:Enzyme Inhibitors; D018260:Gelsolin; D019269:Phosphatidylinositol 4,5-Diphosphate; D018129:Phosphatidylinositol Phosphates; C060980:phosphatidylinositol 3,4-diphosphate; C505407:CASP3 protein, human; C506433:CASP9 protein, human; C505409:Casp3 protein, mouse; C506434:Casp9 protein, mouse; D053148:Caspase 3; D053453:Caspase 9; D020169:Caspases