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Galaz-Montoya M, Wright SJ, Rodriguez GJ, Lichtarge O, Wensel TG. β 2-Adrenergic receptor activation mobilizes intracellular calcium via a non-canonical cAMP-independent signaling pathway. J Biol Chem 2017; 292:9967-9974. [PMID: 28442571 DOI: 10.1074/jbc.m117.787119] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2017] [Revised: 04/24/2017] [Indexed: 11/06/2022] Open
Abstract
Beta adrenergic receptors (βARs) are G-protein-coupled receptors essential for physiological responses to the hormones/neurotransmitters epinephrine and norepinephrine which are found in the nervous system and throughout the body. They are the targets of numerous widely used drugs, especially in the case of the most extensively studied βAR, β2AR, whose ligands are used for asthma and cardiovascular disease. βARs signal through Gαs G-proteins and via activation of adenylyl cyclase and cAMP-dependent protein kinase, but some alternative downstream pathways have also been proposed that could be important for understanding normal physiological functioning of βAR signaling and its disruption in disease. Using fluorescence-based Ca2+ flux assays combined with pharmacology and gene knock-out methods, we discovered a previously unrecognized endogenous pathway in HEK-293 cells whereby β2AR activation leads to robust Ca2+ mobilization from intracellular stores via activation of phospholipase C and opening of inositol trisphosphate (InsP3) receptors. This pathway did not involve cAMP, Gαs, or Gαi or the participation of the other members of the canonical β2AR signaling cascade and, therefore, constitutes a novel signaling mechanism for this receptor. This newly uncovered mechanism for Ca2+ mobilization by β2AR has broad implications for adrenergic signaling, cross-talk with other signaling pathways, and the effects of βAR-directed drugs.
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Affiliation(s)
- Monica Galaz-Montoya
- From the Verna and Marrs McLean Department of Biochemistry and Molecular Biology and
| | - Sara J Wright
- From the Verna and Marrs McLean Department of Biochemistry and Molecular Biology and
| | - Gustavo J Rodriguez
- From the Verna and Marrs McLean Department of Biochemistry and Molecular Biology and
| | - Olivier Lichtarge
- From the Verna and Marrs McLean Department of Biochemistry and Molecular Biology and.,the Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas 77030
| | - Theodore G Wensel
- From the Verna and Marrs McLean Department of Biochemistry and Molecular Biology and
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2
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ISOBE K, YOKOYAMA T, MORIGUCHI-MORI K, KUMAGAI M, SATOH YI, KUJI A, SAINO T. Role of pituitary adenylyl cyclase-activating polypeptide in intracellular calcium dynamics of neurons and satellite cells in rat superior cervical ganglia . Biomed Res 2017; 38:99-109. [DOI: 10.2220/biomedres.38.99] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Affiliation(s)
- Kanako ISOBE
- Department of Anatomy (Cell Biology), Iwate Medical University
- Division of Special Care Dentistry, Department of Developmental Oral Health Science, School of Dentistry, Iwate Medical University
| | - Takuya YOKOYAMA
- Department of Anatomy (Cell Biology), Iwate Medical University
| | - Kasumi MORIGUCHI-MORI
- Division of Special Care Dentistry, Department of Developmental Oral Health Science, School of Dentistry, Iwate Medical University
| | - Miho KUMAGAI
- Division of Special Care Dentistry, Department of Developmental Oral Health Science, School of Dentistry, Iwate Medical University
| | - Yoh-ichi SATOH
- Department of Anatomy (Cell Biology), Iwate Medical University
- Department of Medical Education, Iwate Medical University
| | - Akiyoshi KUJI
- Division of Special Care Dentistry, Department of Developmental Oral Health Science, School of Dentistry, Iwate Medical University
| | - Tomoyuki SAINO
- Department of Anatomy (Cell Biology), Iwate Medical University
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Bragiel AM, Wang D, Pieczonka TD, Shono M, Ishikawa Y. Mechanisms Underlying Activation of α₁-Adrenergic Receptor-Induced Trafficking of AQP5 in Rat Parotid Acinar Cells under Isotonic or Hypotonic Conditions. Int J Mol Sci 2016; 17:ijms17071022. [PMID: 27367668 PMCID: PMC4964398 DOI: 10.3390/ijms17071022] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2016] [Revised: 06/15/2016] [Accepted: 06/23/2016] [Indexed: 11/18/2022] Open
Abstract
Defective cellular trafficking of aquaporin-5 (AQP5) to the apical plasma membrane (APM) in salivary glands is associated with the loss of salivary fluid secretion. To examine mechanisms of α1-adrenoceptor (AR)-induced trafficking of AQP5, immunoconfocal microscopy and Western blot analysis were used to analyze AQP5 localization in parotid tissues stimulated with phenylephrine under different osmolality. Phenylephrine-induced trafficking of AQP5 to the APM and lateral plasma membrane (LPM) was mediated via the α1A-AR subtype, but not the α1B- and α1D-AR subtypes. Phenylephrine-induced trafficking of AQP5 was inhibited by ODQ and KT5823, inhibitors of nitric oxide (NO)-stimulated guanylcyclase (GC) and protein kinase (PK) G, respectively, indicating the involvement of the NO/ soluble (c) GC/PKG signaling pathway. Under isotonic conditions, phenylephrine-induced trafficking was inhibited by La3+, implying the participation of store-operated Ca2+ channel. Under hypotonic conditions, phenylephrine-induced trafficking of AQP5 to the APM was higher than that under isotonic conditions. Under non-stimulated conditions, hypotonicity-induced trafficking of AQP5 to the APM was inhibited by ruthenium red and La3+, suggesting the involvement of extracellular Ca2+ entry. Thus, α1A-AR activation induced the trafficking of AQP5 to the APM and LPM via the Ca2+/ cyclic guanosine monophosphate (cGMP)/PKG signaling pathway, which is associated with store-operated Ca2+ entry.
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Affiliation(s)
- Aneta M Bragiel
- Department of Medical Pharmacology, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15, Kuramoto-cho, Tokushima 770-8504, Japan.
| | - Di Wang
- Department of Medical Pharmacology, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15, Kuramoto-cho, Tokushima 770-8504, Japan.
| | - Tomasz D Pieczonka
- Department of Medical Pharmacology, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15, Kuramoto-cho, Tokushima 770-8504, Japan.
| | - Masayuki Shono
- Support Center for Advanced Medical Sciences, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15, Kuramoto-cho, Tokushima 770-8504, Japan.
| | - Yasuko Ishikawa
- Department of Medical Pharmacology, Institute of Biomedical Sciences, Tokushima University Graduate School, 3-18-15, Kuramoto-cho, Tokushima 770-8504, Japan.
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4
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Copik AJ, Baldys A, Nguyen K, Sahdeo S, Ho H, Kosaka A, Dietrich PJ, Fitch B, Raymond JR, Ford APDW, Button D, Milla ME. Isoproterenol acts as a biased agonist of the alpha-1A-adrenoceptor that selectively activates the MAPK/ERK pathway. PLoS One 2015; 10:e0115701. [PMID: 25606852 PMCID: PMC4301629 DOI: 10.1371/journal.pone.0115701] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2014] [Accepted: 11/26/2014] [Indexed: 11/24/2022] Open
Abstract
The α1A-AR is thought to couple predominantly to the Gαq/PLC pathway and lead to phosphoinositide hydrolysis and calcium mobilization, although certain agonists acting at this receptor have been reported to trigger activation of arachidonic acid formation and MAPK pathways. For several G protein-coupled receptors (GPCRs) agonists can manifest a bias for activation of particular effector signaling output, i.e. not all agonists of a given GPCR generate responses through utilization of the same signaling cascade(s). Previous work with Gαq coupling-defective variants of α1A-AR, as well as a combination of Ca2+ channel blockers, uncovered cross-talk between α1A-AR and β2-AR that leads to potentiation of a Gαq-independent signaling cascade in response to α1A-AR activation. We hypothesized that molecules exist that act as biased agonists to selectively activate this pathway. In this report, isoproterenol (Iso), typically viewed as β-AR-selective agonist, was examined with respect to activation of α1A-AR. α1A-AR selective antagonists were used to specifically block Iso evoked signaling in different cellular backgrounds and confirm its action at α1A-AR. Iso induced signaling at α1A-AR was further interrogated by probing steps along the Gαq /PLC, Gαs and MAPK/ERK pathways. In HEK-293/EBNA cells transiently transduced with α1A-AR, and CHO_α1A-AR stable cells, Iso evoked low potency ERK activity as well as Ca2+ mobilization that could be blocked by α1A-AR selective antagonists. The kinetics of Iso induced Ca2+ transients differed from typical Gαq- mediated Ca2+ mobilization, lacking both the fast IP3R mediated response and the sustained phase of Ca2+ re-entry. Moreover, no inositol phosphate (IP) accumulation could be detected in either cell line after stimulation with Iso, but activation was accompanied by receptor internalization. Data are presented that indicate that Iso represents a novel type of α1A-AR partial agonist with signaling bias toward MAPK/ERK signaling cascade that is likely independent of coupling to Gαq.
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Affiliation(s)
- Alicja. J. Copik
- Biochemical Pharmacology, Inflammation Discovery, Roche Palo Alto LLC, 3401 Hillview Drive, Palo Alto, CA 94304, United States of America
| | - Aleksander Baldys
- Nephrology Division, Department of Medicine, Medical University of South Carolina, and Medical and Research Services, Ralph H Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29425, United States of America
| | - Khanh Nguyen
- Discovery Technologies, Roche Palo Alto LLC, 3401 Hillview Drive, Palo Alto, CA 94304, United States of America
| | - Sunil Sahdeo
- Biochemical Pharmacology, Inflammation Discovery, Roche Palo Alto LLC, 3401 Hillview Drive, Palo Alto, CA 94304, United States of America
| | - Hoangdung Ho
- Discovery Technologies, Roche Palo Alto LLC, 3401 Hillview Drive, Palo Alto, CA 94304, United States of America
| | - Alan Kosaka
- Discovery Technologies, Roche Palo Alto LLC, 3401 Hillview Drive, Palo Alto, CA 94304, United States of America
| | - Paul J. Dietrich
- Discovery Technologies, Roche Palo Alto LLC, 3401 Hillview Drive, Palo Alto, CA 94304, United States of America
| | - Bill Fitch
- Discovery Technologies, Roche Palo Alto LLC, 3401 Hillview Drive, Palo Alto, CA 94304, United States of America
| | - John R. Raymond
- Nephrology Division, Department of Medicine, Medical University of South Carolina, and Medical and Research Services, Ralph H Johnson Veterans Affairs Medical Center, Charleston, South Carolina 29425, United States of America
| | - Anthony P. D. W. Ford
- Biochemical Pharmacology, Inflammation Discovery, Roche Palo Alto LLC, 3401 Hillview Drive, Palo Alto, CA 94304, United States of America
| | - Donald Button
- Biochemical Pharmacology, Inflammation Discovery, Roche Palo Alto LLC, 3401 Hillview Drive, Palo Alto, CA 94304, United States of America
| | - Marcos E. Milla
- Biochemical Pharmacology, Inflammation Discovery, Roche Palo Alto LLC, 3401 Hillview Drive, Palo Alto, CA 94304, United States of America
- * E-mail:
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Fukui H, Suyama Y, Iwachido T, Miwa E. Possible Involvement of β1 Receptors in Various Emetogen-Induced Increases in Salivary Amylase Activity in Rats. J Pharmacol Sci 2011; 115:69-74. [DOI: 10.1254/jphs.10265fp] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
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Inagaki T, Ono K, Masuda W, Iida T, Hosokawa R, Inenaga K. Differences in the Ca2+ response resulting from neurotransmitter stimulations of rat parotid acini and ducts. Auton Neurosci 2010; 154:102-7. [PMID: 20096649 DOI: 10.1016/j.autneu.2009.12.005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2009] [Revised: 11/19/2009] [Accepted: 12/09/2009] [Indexed: 10/19/2022]
Abstract
There are few data available regarding the differences in intracellular Ca2+ responses of parotid acinar and ductal cells. This study investigated the Ca2+ mobilization that was induced by the chemical stimulation of acinar and ductal cells from rat parotid glands. In fura-2 loaded parotid cells, carbachol increased the intracellular Ca2+ concentration ([Ca2+](i)) to a greater extent in the acinar cells than in the ductal cells, but noradrenaline increased the [Ca2+](i) in the ductal cells more than in the acinar cells. Although there was no difference in the alpha1-adrenergic receptor agonist phenylephrine-induced Ca2+ mobilization between acini and ducts, the beta-adrenergic receptor agonist isoproterenol increased the [Ca2+](i) in only the ductal cells. Additionally, the effects of non-adrenergic, non-cholinergic neurotransmitters were investigated. Substance P and ATP increased the [Ca2+](i) in parotid acini and/or ducts. A substance P-induced Ca2+ response was observed in only acini, while the ATP-induced Ca2+ response was significantly higher in ducts than in acini. These results suggest that parotid acini have a greater sensitivity to cholinergic and substance P stimulation and a lesser sensitivity to beta-adrenergic and ATP stimulation than the ductal cells. In light of these results, substance P and isoproterenol will be useful for identifying parotid acini and ducts, respectively.
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Affiliation(s)
- Tomohiro Inagaki
- Department of Biosciences, Kyushu Dental College, 2-6-1 Manazuru, Kokurakitaku, Kitakyushu, Fukuoka 803-8580, Japan
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7
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Imai A, Fukuda M, Yoshie S, Nashida T, Shimomura H. Redistribution of Rab27-specific effector Slac2-c, but not Slp4-a, after isoproterenol-stimulation in rat parotid acinar cells. Arch Oral Biol 2009; 54:361-8. [PMID: 19185850 DOI: 10.1016/j.archoralbio.2008.12.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2008] [Revised: 12/02/2008] [Accepted: 12/31/2008] [Indexed: 12/16/2022]
Abstract
Small GTPase Rab27 has been implicated in the regulation of different types of membrane trafficking, including melanosome transport and various regulated secretion events. We have previously shown that Rab27 and its effectors, Slac2-c/MyRIP and Slp4-a/granuphilin-a, are involved in the control of isoproterenol (IPR)-induced amylase release from rat parotid acinar cells. The ability of Rab to interact with the specific effectors is important. However, little is known about the fate of these effectors after beta-adrenergic stimulation in parotid acinar cells. The present study investigated changes in intracellular redistribution of Slac2-c and Slp4-a in parotid acinar cells after IPR treatment. Subcellular fractionation studies detected Slac2-c and Slp4-a in the apical plasma membrane (APM) and secretory granules under resting conditions. After 5min of IPR treatment, Slac2-c was rapidly recruited to the luminal site, but after 30 min, the amount of Slac2-c in the APM fraction was reduced by approximately 80% compared to the increased level after 5 min of IPR treatment. Such reductions in Slac2-c are likely caused by the translocation of Slac2-c from the APM to the cytosol. In addition, we found that Slac2-c in the cytosolic fraction, but not other fractions, disappeared in the presence of Ca(2+). Since Slac2-c contains multiple PEST-like sequences (i.e., potential signals for rapid protein degradation), we suggest that Slac2-c is Ca(2+)-dependently proteolyzed in the cytosol after exocytosis. In contrast, intracellular localization and expression levels of Slp4-a in parotid acinar cells were unaltered even after beta-stimulation, indicating completely different fates for the two Rab27 effectors after beta-stimulation.
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Affiliation(s)
- Akane Imai
- Department of Biochemistry, School of Life Dentistry at Niigata, The Nippon Dental University, 1-8, Hamaura-cho, Chuo-ku, Niigata 951-8580, Japan.
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8
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Romanenko VG, Nakamoto T, Srivastava A, Begenisich T, Melvin JE. Regulation of membrane potential and fluid secretion by Ca2+-activated K+ channels in mouse submandibular glands. J Physiol 2007; 581:801-17. [PMID: 17379640 PMCID: PMC2075181 DOI: 10.1113/jphysiol.2006.127498] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
We have recently shown that the IK1 and maxi-K channels in parotid salivary gland acinar cells are encoded by the K(Ca)3.1 and K(Ca)1.1 genes, respectively, and in vivo stimulated parotid secretion is severely reduced in double-null mice. The current study tested whether submandibular acinar cell function also relies on these channels. We found that the K(+) currents in submandibular acinar cells have the biophysical and pharmacological footprints of IK1 and maxi-K channels and their molecular identities were confirmed by the loss of these currents in K(Ca)3.1- and K(Ca)1.1-null mice. Unexpectedly, the pilocarpine-stimulated in vivo fluid secretion from submandibular glands was essentially normal in double-null mice. This result and the possibility of side-effects of pilocarpine on the nervous system, led us to develop an ex vivo fluid secretion assay. Fluid secretion from the ex vivo assay was substantially (about 75%) reduced in animals with both K(+) channel genes ablated - strongly suggesting systemic complications with the in vivo assay. Additional experiments focusing on the membrane potential in isolated submandibular acinar cells revealed mechanistic details underlying fluid secretion in K(+) channel-deficient mice. The membrane potential of submandibular acinar cells from wild-type mice remained strongly hyperpolarized (-55 +/- 2 mV) relative to the Cl(-) equilibrium potential (-24 mV) during muscarinic stimulation. Similar hyperpolarizations were observed in K(Ca)3.1- and K(Ca)1.1-null mice (-51 +/- 3 and -48 +/- 3 mV, respectively), consistent with the normal fluid secretion produced ex vivo. In contrast, acinar cells from double K(Ca)3.1/K(Ca)1.1-null mice were only slightly hyperpolarized (-35 +/- 2 mV) also consistent with the ex vivo (but not in vivo) results. Finally, we found that the modest hyperpolarization of cells from the double-null mice was maintained by the electrogenic Na(+),K(+)-ATPase.
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Affiliation(s)
- Victor G Romanenko
- Center for Oral Biology in the Aab Institute of Biomedical Sciences and Department of Pharmacology and Physiology, University of Rochester School of Medicine and Dentistry, Rochester, NY 14642, USA
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Tanimura A, Tojyo Y. [Regulation of fluid and electrolyte secretion and exocytosis in salivary acinar cells]. Nihon Yakurigaku Zasshi 2006; 127:249-55. [PMID: 16755075 DOI: 10.1254/fpj.127.249] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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10
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Thompson J, Begenisich T. Membrane-delimited inhibition of maxi-K channel activity by the intermediate conductance Ca2+-activated K channel. ACTA ACUST UNITED AC 2006; 127:159-69. [PMID: 16418402 PMCID: PMC2151496 DOI: 10.1085/jgp.200509457] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
The complexity of mammalian physiology requires a diverse array of ion channel proteins. This diversity extends even to a single family of channels. For example, the family of Ca2+-activated K channels contains three structural subfamilies characterized by small, intermediate, and large single channel conductances. Many cells and tissues, including neurons, vascular smooth muscle, endothelial cells, macrophages, and salivary glands express more than a single class of these channels, raising questions about their specific physiological roles. We demonstrate here a novel interaction between two types of Ca2+-activated K channels: maxi-K channels, encoded by the KCa1.1 gene, and IK1 channels (KCa3.1). In both native parotid acinar cells and in a heterologous expression system, activation of IK1 channels inhibits maxi-K activity. This interaction was independent of the mode of activation of the IK1 channels: direct application of Ca2+, muscarinic receptor stimulation, or by direct chemical activation of the IK1 channels. The IK1-induced inhibition of maxi-K activity occurred in small, cell-free membrane patches and was due to a reduction in the maxi-K channel open probability and not to a change in the single channel current level. These data suggest that IK1 channels inhibit maxi-K channel activity via a direct, membrane-delimited interaction between the channel proteins. A quantitative analysis indicates that each maxi-K channel may be surrounded by four IK1 channels and will be inhibited if any one of these IK1 channels opens. This novel, regulated inhibition of maxi-K channels by activation of IK1 adds to the complexity of the properties of these Ca2+-activated K channels and likely contributes to the diversity of their functional roles.
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Affiliation(s)
- Jill Thompson
- Department of Pharmacology, University of Rochester Medical Center, Rochester, NY 14642, USA
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Nezu A, Morita T, Tanimura A, Tojyo Y. Comparison of agonist-induced Ca2+ responses in rat submandibular acini and ducts. Arch Oral Biol 2005; 50:585-92. [PMID: 15848152 DOI: 10.1016/j.archoralbio.2004.07.014] [Citation(s) in RCA: 14] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2004] [Accepted: 07/19/2004] [Indexed: 10/26/2022]
Abstract
Changes in intracellular Ca(2+) concentration ([Ca(2+)]i) induced by agonists were simultaneously monitored in rat submandibular acini and ducts using a Ca(2+) imaging system. Substance P (SP) elicited marked increases in [Ca(2+)]i in acini but not in ducts. Carbachol (CCh) increased [Ca(2+)]i in both acini and ducts, but the maximal level was higher in acini than in ducts. In contrast, epinephrine (Epi) also induced an increase in [Ca(2+)]i in acini and ducts, but to a greater extent in ducts than in acini. Isoproterenol (ISO) caused a small but significant increase in [Ca(2+)]i in ducts but not acini. Reverse transcriptase-polymerase chain reaction (RT-PCR) analysis using total RNA extracted from highly purified acinar and ductal cells showed that substance P receptor mRNA was present in acini at higher levels than in ducts. In contrast, alpha(1a)-adrenoceptor mRNA was more strongly expressed in ducts than in acini. The muscarinic receptors (M(3) and M(5)) and beta-adrenoceptors (beta(1) and beta(2)) were expressed at equivalent levels in both cell types. These results confirm that acini and ducts exhibit significant differences in agonist-induced Ca(2+) responses. Furthermore, substance P- and epinephrine-induced Ca(2+) responses were consistent with receptor mRNA expression in acini and ducts, but carbachol- and isoproterenol-induced [Ca(2+)]i increases were not.
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Affiliation(s)
- Akihiro Nezu
- Department of Dental Pharmacology, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido 061-0293, Japan.
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Looms D, Tritsaris K, Pedersen AM, Nauntofte B, Dissing S. Nitric oxide signalling in salivary glands. J Oral Pathol Med 2002; 31:569-84. [PMID: 12406302 DOI: 10.1034/j.1600-0714.2002.00047.x] [Citation(s) in RCA: 36] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022]
Abstract
Nitric oxide (NO) plays multiple roles in both intracellular and extracellular signalling mechanisms with implications for health and disease. This review focuses on the role of NO signalling in salivary secretion. Attention will be paid primarily to endogenous NO production in acinar cells resulting from specific receptor stimulation and to NO-regulated Ca2+ homeostasis. Due to the fact that NO readily crosses membranes by simple diffusion, endogenous NO may play a physiological role in processes as diverse as modifying the secretory output, controlling blood supply to the gland, modulating transmitter output from nerve endings, participating in the host defence barrier, and affecting growth and differentiation of surrounding tissue. Furthermore, the role of NO in the pathogenesis of human oral diseases will be considered.
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Affiliation(s)
- Dagnia Looms
- Department of Medical Physiology, Faculty of Health Sciences, Panum Institute, University of Copenhagen, Denmark
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Busch L, Sterin-Borda L, Borda E. Differences in the regulatory mechanism of amylase release by rat parotid and submandibular glands. Arch Oral Biol 2002; 47:717-22. [PMID: 12356503 DOI: 10.1016/s0003-9969(02)00057-2] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
It is not known whether the mechanisms involved in amylase release in submandibular and parotid glands are similar. Here, the participation of different signalling pathways in amylase release by the parotid and submandibular glands of the male rat was compared by studying the secretory response after beta-adrenergic stimulation. The beta-adrenergic agonist isoproterenol induced an increase of cAMP in both salivary glands, but while in the parotid it triggered amylase release, in the submandibular it was unable to increase amylase secretion. Parotid amylase release was dependent on adenylate cyclase activation, as SQ-22536 inhibited the secretory effect. In contrast, submandibular amylase secretion did not depend on the intracellular concentration of cAMP, as SQ-22536 did not modify its secretory response. Moreover, other activators of adenylate cyclase, such as forskolin and prostaglandin E2, also failed to modify amylase release by the submandibular gland. Neither ionophores nor calcium-blocking agents, as well as calcium-calmodulin and nitric oxide synthase inhibitors, were effective in modifying basal amylase release by the submandibular gland. However, the disruption of microfilaments with cytochalasin B, but not the disruption of microtubules with colchicine, prevented amylase release in that gland. It is concluded that amylase exocytosis in the submandibular gland is a constitutive non-regulated phenomenon, as it is independent of extracellular or intracellular signals. It depends only on the integrity of the microfilaments, probably used by the vesicles to travel from the Golgi apparatus to the plasma membrane.
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Affiliation(s)
- Lucila Busch
- Pharmacology Unit, School of Dentistry, University of Buenos Aires, Marcelo T. de Alvear 2142, 1122AAH, Buenos Aires, Argentina.
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Bruce JIE, Shuttleworth TJ, Giovannucci DR, Yule DI. Phosphorylation of inositol 1,4,5-trisphosphate receptors in parotid acinar cells. A mechanism for the synergistic effects of cAMP on Ca2+ signaling. J Biol Chem 2002; 277:1340-8. [PMID: 11694504 DOI: 10.1074/jbc.m106609200] [Citation(s) in RCA: 124] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Acetylcholine-evoked secretion from the parotid gland is substantially potentiated by cAMP-raising agonists. A potential locus for the action of cAMP is the intracellular signaling pathway resulting in elevated cytosolic calcium levels ([Ca(2+)](i)). This hypothesis was tested in mouse parotid acinar cells. Forskolin dramatically potentiated the carbachol-evoked increase in [Ca(2+)](i), converted oscillatory [Ca(2+)](i) changes into a sustained [Ca(2+)](i) increase, and caused subthreshold concentrations of carbachol to increase [Ca(2+)](i) measurably. This potentiation was found to be independent of Ca(2+) entry and inositol 1,4,5-trisphosphate (InsP(3)) production, suggesting that cAMP-mediated effects on Ca(2+) release was the major underlying mechanism. Consistent with this hypothesis, dibutyryl cAMP dramatically potentiated InsP(3)-evoked Ca(2+) release from streptolysin-O-permeabilized cells. Furthermore, type II InsP(3) receptors (InsP(3)R) were shown to be directly phosphorylated by a protein kinase A (PKA)-mediated mechanism after treatment with forskolin. In contrast, no evidence was obtained to support direct PKA-mediated activation of ryanodine receptors (RyRs). However, inhibition of RyRs in intact cells, demonstrated a role for RyRs in propagating Ca(2+) oscillations and amplifying potentiated Ca(2+) release from InsP(3)Rs. These data indicate that potentiation of Ca(2+) release is primarily the result of PKA-mediated phosphorylation of InsP(3)Rs, and may largely explain the synergistic relationship between cAMP-raising agonists and acetylcholine-evoked secretion in the parotid. In addition, this report supports the emerging consensus that phosphorylation at the level of the Ca(2+) release machinery is a broadly important mechanism by which cells can regulate Ca(2+)-mediated processes.
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Affiliation(s)
- Jason I E Bruce
- Department of Pharmacology & Physiology, School of Medicine and Dentistry, University of Rochester Medical Center, Rochester, New York 14642, USA.
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15
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Nezu A, Tanimura A, Tojyo Y. Characterization of the ca2 + response mediated by activation of beta-adrenoceptors in rat submandibular ducts. JAPANESE JOURNAL OF PHARMACOLOGY 2000; 84:25-31. [PMID: 11043449 DOI: 10.1254/jjp.84.25] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
The Ca2+ signaling mediated by activation of beta-adrenoceptors was studied in a purified preparation of ducts from rat submandibular glands. At concentrations above 1 nM, isoproterenol (ISO) caused a small but significant increase in cytosolic Ca2+ concentration ([Ca2+]i). The ISO-induced increase in [Ca2+]i was completely inhibited by the beta-adrenoceptor antagonist propranolol but not by the alpha-adrenoceptor antagonist phentolamine. Forskolin was able to mimic the Ca2+ response to ISO. These results suggest that the ISO-induced increase in [Ca2+]i in rat submandibular ducts is mediated by an accumulation of cAMP resulting from activation of beta-adrenoceptors. In the absence of extracellular Ca2+, ISO or forskolin caused a transient increase in [Ca2+]i, indicating Ca2+ mobilization from intracellular Ca2+ stores. Further, stimulation with ISO failed to mobilize Ca2+ after the depletion of intracellular Ca2+ stores by phenylephrine or carbachol, suggesting that the cAMP-mediated increase in [Ca2+]i is due to a Ca2+ release from inositol trisphosphate (IP3)-sensitive Ca2+ stores. As ISO did not stimulate a detectable production of IP3, the cAMP-mediated Ca2+ mobilization may be evoked by a mechanism different from activation of phosphoinositide hydrolysis.
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Affiliation(s)
- A Nezu
- Department of Dental Pharmacology, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Japan
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16
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Fujita-Yoshigaki J. Simulation of regulated exocytosis of amylase from salivary parotid acinar cells by a consecutive reaction model comprising two sequential first-order reactions. J Theor Biol 2000; 204:165-77. [PMID: 10887899 DOI: 10.1006/jtbi.2000.2009] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Amylase secretion from parotid acinar cells results from stimulus-regulated fusion of apical membrane and secretory granules that contain amylase. The time course of amylase secretion induced by various secretagogues has been reported. Calcium-mobilizing agonists such as carbamylcholine and substance P induce rapid and transient secretion while cAMP-mobilizing agonists such as isoproterenol cause long-term secretion. Combination of these two types of agonists results in a rapid and high rate of secretion. To explain the various time courses of these stimulations, it was assumed that amylase secretion is a consecutive reaction that consists of two first-order reactions. It was postulated that secretory granules were classified into three states: (A) pre-docked, (B) docked, and (C) fusion. The simple simulation could explain the time course of amylase secretion induced by various secretagogues by simply changing the rate constants for docking (reaction A to B) and fusion (reaction B to C) steps. It was also found that calcium mainly enhances the last fusion step and that cAMP activates the docking step. The amount of docked granules is estimated to be quite small, which accounts for why amylase secretion is regulated mainly by cAMP. The effects of the two types of secretagogues were synergistic, meaning that their intracellular signaling pathways are independent. At the same time, this also suggests that basal and enhanced secretion induced by two types of agonists have the same exocytotic process and that two stimuli independently activate the same machinery that mediates docking or fusion. This simulation is useful in analysis of the effects of secretion modulators and the molecular mechanism of amylase secretion.
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Affiliation(s)
- J Fujita-Yoshigaki
- Department of Physiology, Nihon University School of Dentistry at Matsudo, Chiba, Japan.
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Watson EL, Jacobson KL, Singh JC, Idzerda R, Ott SM, DiJulio DH, Wong ST, Storm DR. The type 8 adenylyl cyclase is critical for Ca2+ stimulation of cAMP accumulation in mouse parotid acini. J Biol Chem 2000; 275:14691-9. [PMID: 10799557 DOI: 10.1074/jbc.275.19.14691] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Capacitative Ca(2+) entry stimulates cAMP synthesis in mouse parotid acini, suggesting that one of the Ca(2+)-sensitive adenylyl cyclases (AC1 or AC8) may play an important role in the regulation of parotid function (Watson, E. L., Wu, Z., Jacobson, K. L., Storm, D. R., Singh, J. C., and Ott, S. M. (1998) Am. J. Physiol. 274, C557-C565). To evaluate the role of AC1 and AC8 in Ca(2+) stimulation of cAMP synthesis in parotid cells, acini were isolated from AC1 mutant (AC1-KO) and AC8 mutant (AC8-KO) mice and analyzed for Ca(2+) stimulation of intracellular cAMP levels. Although Ca(2+) stimulation of intracellular cAMP levels in acini from AC1-KO mice was indistinguishable from wild type mice, acini from AC8-KO mice showed no Ca(2+)-stimulated cAMP accumulation. This indicates that AC8, but not AC1, plays a major role in coupling Ca(2+) signals to cAMP synthesis in parotid acini. Interestingly, treatment of acini from AC8-KO mice with agents, i.e. carbachol and thapsigargin that increase intracellular Ca(2+), lowered cAMP levels. This decrease was dependent upon Ca(2+) influx and independent of phosphodiesterase activation. Immunoblot analysis revealed that AC5/6 and AC3 are expressed in parotid glands. Inhibition of calmodulin (CaM) kinase II with KN-62, or inclusion of the CaM inhibitor, calmidazolium, did not prevent agonist-induced inhibition of stimulated cAMP accumulation. In vitro studies revealed that Ca(2+), independently of CaM, inhibited isoproterenol-stimulated AC. Data suggest that agonist augmentation of stimulated cAMP levels is due to activation of AC8 in mouse parotid acini, and strongly support a role for AC5/6 in the inhibition of stimulated cAMP levels.
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Affiliation(s)
- E L Watson
- Department of Oral Biology, University of Washington, Seattle, Washington 98195, USA.
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Tanimura A, Nezu A, Tojyo Y, Matsumoto Y. Isoproterenol potentiates alpha-adrenergic and muscarinic receptor-mediated Ca2+ response in rat parotid cells. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:C1282-7. [PMID: 10362590 DOI: 10.1152/ajpcell.1999.276.6.c1282] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The effects of the cAMP pathway on the Ca2+ response elicited by phospholipase C-coupled receptor stimulations were studied in rat parotid cells. Although 1 microM isoproterenol (Iso) itself had no effect on the cytosolic Ca2+ concentration, the pretreatment with Iso potentiated Ca2+ responses evoked by phenylephrine. The potentiating effect of Iso was attributed to a shifting of the concentration-response curves of phenylephrine to the left and an increase in the maximal response. Half-maximal potentiation occurred at 3 nM Iso. Iso also potentiated the Ca2+ response elicited by carbachol. The potentiating effect of Iso was mimicked by forskolin (10 microM) and dibutyryl adenosine 3',5'-cyclic monophosphate (2 mM) and was blocked by 10 microM H-89. Iso potentiated the phenylephrine-induced Ca2+ response in the absence of extracellular Ca2+, but Iso did not increase the inositol trisphosphate (IP3) production induced by phenylephrine. These results suggest that the potentiation of the Ca2+ response can be attributed to a sensitization of IP3 receptors by cAMP-dependent protein kinase.
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Affiliation(s)
- A Tanimura
- Department of Dental Pharmacology, School of Dentistry, Health Sciences University of Hokkaido, Ishikari-Tobetsu, Hokkaido 061-0293, Japan.
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