Cyclic AMP has distinct effects from Ca 2+ in evoking priming and fusion/exocytosis in parotid amylase secretion

Yoshimura, Keiichi; Fujita-Yoshigaki, Junko; Murakami, Masataka; Segawa, Akihisa

doi:10.1007/s00424-002-0844-7

Cited by 23 publications

(18 citation statements)

References 19 publications

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“…Occasionally, one or two stepwise events were seen superimposed on the smooth change in C m . The absence of C m steps was surprising because 1 M Iso has been shown to efficiently induce amylase release from parotid acini (34) and may indicate that adrenergic signaling is compromised in single cells or that another vesicle population whose fusions cannot be resolved as individual events can be induced by lower concentrations of agonist to release amylase.…”

Section: Exocytosis Induced By Camp and Camentioning

confidence: 99%

“…For example, in parotid and pancreatic acinar cells, fluid and protein secretion is regulated by both parasympathetic and sympathetic input. In the parotid, cholinergic or ␤-adrenergic receptor activation evokes rises in cytosolic Ca 2ϩ concentration ([Ca 2ϩ ] i ) and CAMP concentration, respectively, and both messengers can act as intracellular messengers to induce amylase release (34). A primary difference between parotid and pancreatic acinar cells is that robust exocytosis in the parotid can be stimulated by increased cytosolic levels of cAMP.…”

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confidence: 99%

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Spatiotemporal analysis of exocytosis in mouse parotid acinar cells

Chen¹,

Warner²,

Yule³

et al. 2005

American Journal of Physiology-Cell Physiology

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Exocrine cells of the digestive system are specialized to secrete protein and fluid in response to neuronal and/or hormonal input. Although morphologically similar, parotid and pancreatic acinar cells exhibit important functional divergence in Ca2+ signaling properties. To address whether there are fundamental differences in exocytotic release of digestive enzyme from exocrine cells of salivary gland versus pancreas, we applied electrophysiological and optical methods to investigate spatial and temporal characteristics of zymogen-containing secretory granule fusion at the single-acinar cell level by direct or agonist-induced Ca2+ and cAMP elevation. Temporally resolved membrane capacitance measurements revealed that two apparent phases of exocytosis were induced by Ca2+ elevation: a rapidly activated initial phase that could not be resolved as individual fusion events and a second phase that was activated after a delay, increased in a staircaselike fashion, was augmented by cAMP elevation, and likely reflected both sequential compound and multivesicular fusion of zymogen-containing granules. Optical measurements of exocytosis with time-differential imaging analysis revealed that zymogen granule fusion was induced after a minimum delay of ∼200 ms, occurred initially at apical and basolateral borders of acinar cells, and under strong stimulation proceeded from apical pole to deeper regions of the cell interior. Zymogen granule fusions appeared to coordinate subsequent fusions and produced persistent structures that generally lasted several minutes. In addition, parotid gland slices were used to assess secretory dynamics in a more physiological context. Parotid acinar cells were shown to exhibit both similar and divergent properties compared with the better-studied pancreatic acinar cell regarding spatial organization and kinetics of exocytotic fusion of zymogen granules.

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Section: Exocytosis Induced By Camp and Camentioning

confidence: 99%

mentioning

confidence: 99%

Spatiotemporal analysis of exocytosis in mouse parotid acinar cells

Chen¹,

Warner²,

Yule³

et al. 2005

American Journal of Physiology-Cell Physiology

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“…Recently, Yoshimura et al (45) suggested that cAMP sensitizes induced amylase secretion by priming zymogen granule Fig. 8.…”

Section: ϫ12mentioning

confidence: 99%

Mutual dependence of VIP/PACAP and CCK receptor signaling for a physiological role in duck exocrine pancreatic secretion

Xiao

Cui

2004

American Journal of Physiology-Regulatory, Integrative and Comp

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Unlike in rodents, CCK has not been established as a physiological regulator in avian exocrine pancreatic secretion. In the isolated duck pancreatic acini, 1 nM CCK was required for stimulation of amylase secretion, maximal effect being achieved at 10 nM; picomolar CCK was without effect. Vasoactive intestinal peptide (VIP)/pituitary adenylate cyclase activating peptide (PACAP) receptor (VPAC) agonists PACAP-38 and PACAP-27 (10-12-10-7 M) alone had no effect, but made picomolar CCK effective. VPAC agonist VIP 10-10-10-7 M stimulated amylase secretion marginally, but made CCK 10-12-10-10 M effective also. PACAP-27 and VIP both shifted the maximal CCK concentration from 10-8 to 10-9 M. This sensitizing effect was mimicked by forskolin. CCK dose dependently induced intracellular Ca2+ concentration ([Ca2+]i) oscillations. PACAP-38 (1 nM), PACAP-27 (1 nM), VIP (10 nM), or forskolin (10 μM) alone did not stimulate [Ca2+]i increase, neither did they modulate CCK (1 nM)-induced oscillations; but when they were added to cells simultaneously exposed to subthreshold CCK (10 pM), calcium spikes emerged. Amylase secretion induced by the simultaneous presence of 10 pM CCK and VPAC agonists was completely blocked by removing extracellular calcium, but the protein kinase C inhibitor staurosporine (1 μM) was without effect. CCK (10 nM)-induced secretion was inhibited by CCK1 receptor antagonist FK480 (1 μM). Gastrin from 10-12 to 10-6 M did not stimulate amylase secretion nor did it (100 nM) induce [Ca2+]i increase. The above data suggest that duck pancreatic acini possess both CCK1 and VPAC receptors; simultaneous activation of both is required for each to play a physiological role.

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“…Colchicine may affect some intracellular signaling sites between receptors and Cl − channels, in turn modulating protein secretion, channel activity, and receptor function (4,12,19,24 (4,5,24,37). The interaction between Ca 2+ and cAMP signaling systems enhances amylase secretion (21,39), but this enhancement does not require cortical actin integrity. Exocytosis of amylase consists of three types of processes: constitutive-like exocytosis, minor regulated exocytosis, and major regulated exocytosis (6).…”

Section: Discussionmentioning

confidence: 99%

“…This interaction modulates both signaling systems (28), which exert different actions on amylase secretion (6,23,39) and translocation of Rap1 (8), but a similar action on cofilin dephosphorylation (35). Some of these processes might be sensitive to changes in the cytoskeletal integration.…”

Section: References Interaction Of Camentioning

confidence: 99%

Involvement of cytoskeletal integrity in the regulation of Cl- and amylase secretion from rat parotid acinar cells

et al. 2008

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The cytoskeleton serves as a signal modulator for Ca 2+ and cAMP-regulated cell functions including the secretion of ions and granule contents. The interaction between Ca 2+ and cAMP signaling systems potentiates amylase secretion and suppresses Cl − secretion in the parotid glands. In this study, we investigated the role of the cytoskeleton in the modulation of Cl − and amylase secretion from rat parotid acinar cells upon activation of each intracellular signaling system and their interaction. Cytochalasin D markedly inhibited the Ca 2+ -activated outwardly rectifying Cl − current at positive membrane potentials and carbachol (CCh)-induced Cl − currents in the whole-cell configuration at −80 mV, whereas colchicine enhanced Cl − currents. Cytochalasin D, but not colchicine, markedly inhibited CCh-induced Cl − secretion. Synergistic actions of CCh and forskolin on Cl − and amylase secretion were observed even in the presence of cytochalasin D. These results suggest that the synergistic effects of Ca 2+ and cAMP signaling systems on amylase and Cl − secretion do not require actin filament integrity but that secretion by the two signals themselves does require actin filament integrity.Actin and tubulin cytoskeletons are involved in the regulation of cell morphology and intracellular transport. They also affect the membrane permeability and secretory functions of glandular cells; cytoskeletal integrity modulates amylase secretion by β-adrenergic agonists (4,5,24,37) and cytoskeletal organization is related to the regulation of ion channels (1, 12), exchangers (16) and transporters (7) involved in the secretion of salivary fluid during cholinergic stimulation (22,27). Cytoskeletal integrity might regulate Cl −

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Cyclic AMP has distinct effects from Ca 2+ in evoking priming and fusion/exocytosis in parotid amylase secretion

Cited by 23 publications

References 19 publications

Spatiotemporal analysis of exocytosis in mouse parotid acinar cells

Spatiotemporal analysis of exocytosis in mouse parotid acinar cells

Mutual dependence of VIP/PACAP and CCK receptor signaling for a physiological role in duck exocrine pancreatic secretion

Involvement of cytoskeletal integrity in the regulation of Cl- and amylase secretion from rat parotid acinar cells

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