title: Myosin IIB and F-actin control apical vacuolar morphology and histamine-induced trafficking of H-K-ATPase-containing tubulovesicles in gastric parietal cells.
abstract: Selective inhibitors of myosin or actin function and confocal microscopy were used to test the role of an actomyosin complex in controlling morphology, trafficking, and fusion of tubulovesicles (TV) containing H-K-ATPase with the apical secretory canaliculus (ASC) of primary-cultured rabbit gastric parietal cells. In resting cells, myosin IIB and IIC, ezrin, and F-actin were associated with ASC, whereas H-K-ATPase localized to intracellular TV. Histamine caused fusion of TV with ASC and subsequent expansion resulting from HCl and water secretion; F-actin and ezrin remained associated with ASC whereas myosin IIB and IIC appeared to dissociate from ASC and relocalize to the cytoplasm. ML-7 (inhibits myosin light chain kinase) caused ASC of resting cells to collapse and most myosin IIB, F-actin, and ezrin to dissociate from ASC. TV were unaffected by ML-7. Jasplakinolide (stabilizes F-actin) caused ASC to develop large blebs to which actin, myosin II, and ezrin, as well as tubulin, were prominently localized. When added prior to stimulation, ML-7 and jasplakinolide prevented normal histamine-stimulated transformations of ASC/TV and the cytoskeleton, but they did not affect cells that had been previously stimulated with histamine. These results indicate that dynamic pools of actomyosin are required for maintenance of ASC structure in resting cells and for trafficking of TV to ASC during histamine stimulation. However, the dynamic pools of actomyosin are not required once the histamine-stimulated transformation of TV/ASC and cytoskeleton has occurred. These results also show that vesicle trafficking in parietal cells shares mechanisms with similar processes in renal collecting duct cells, neuronal synapses, and skeletal muscle.
authors.affiliation: Department of Molecular and Cell Biology, University of California, Berkeley, California; and.
authors.forename: Paramasivam
authors.initials: P
authors.lastname: Natarajan
authors.forename: James M
authors.initials: JM
authors.lastname: Crothers
authors.forename: Jared E
authors.initials: JE
authors.lastname: Rosen
authors.forename: Stephanie L
authors.initials: SL
authors.lastname: Nakada
authors.forename: Milap
authors.initials: M
authors.lastname: Rakholia
authors.forename: Curtis T
authors.initials: CT
authors.lastname: Okamoto
authors.forename: John G
authors.initials: JG
authors.lastname: Forte
authors.forename: Terry E
authors.initials: TE
authors.lastname: Machen
mesh_terms: D000199:Actins / Q000378:metabolism*; D000818:Animals; D001381:Azepines / Q000494:pharmacology; D001692:Biological Transport / Q000187:drug effects / Q000502:physiology; D002468:Cell Physiological Phenomena / Q000187:drug effects; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000494:pharmacology; D017506:H(+)-K(+)-Exchanging ATPase / Q000378:metabolism; D009281:Naphthalenes / Q000494:pharmacology; D024501:Nonmuscle Myosin Type IIB / Q000378:metabolism*; D010295:Parietal Cells, Gastric / Q000378:metabolism / Q000473:pathology; D011817:Rabbits; D022161:Transport Vesicles / Q000187:drug effects / Q000502:physiology
chemical_list: D000199:Actins; D001381:Azepines; D004791:Enzyme Inhibitors; D009281:Naphthalenes; C070571:ML 7; D024501:Nonmuscle Myosin Type IIB; D017506:H(+)-K(+)-Exchanging ATPase
keywords: F-actin; membrane dynamics; nonmuscle myosin II; vesicle trafficking