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Greenberg HZE, Carlton-Carew SRE, Zargaran AK, Jahan KS, Birnbaumer L, Albert AP. Heteromeric TRPV4/TRPC1 channels mediate calcium-sensing receptor-induced relaxations and nitric oxide production in mesenteric arteries: comparative study using wild-type and TRPC1 -/- mice. Channels (Austin) 2019; 13:410-423. [PMID: 31603369 PMCID: PMC7426016 DOI: 10.1080/19336950.2019.1673131] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
We have previously provided pharmacological evidence that stimulation of calcium-sensing receptors (CaSR) induces endothelium-dependent relaxations of rabbit mesenteric arteries through activation of heteromeric TRPV4/TRPC1 channels and nitric oxide (NO) production. The present study further investigates the role of heteromeric TRPV4/TRPC1 channels in these CaSR-induced vascular responses by comparing responses in mesenteric arteries from wild-type (WT) and TRPC1-/- mice. In WT mice, stimulation of CaSR induced endothelium-dependent relaxations of pre-contracted tone and NO generation in endothelial cells (ECs), which were inhibited by the TRPV4 channel blocker RN1734 and the TRPC1 blocking antibody T1E3. In addition, TRPV4 and TRPC1 proteins were colocalised at, or close to, the plasma membrane of endothelial cells (ECs) from WT mice. In contrast, in TRPC1-/- mice, CaSR-mediated vasorelaxations and NO generation were greatly reduced, unaffected by T1E3, but blocked by RN1734. In addition, the TRPV4 agonist GSK1016790A (GSK) induced endothelium-dependent vasorelaxations which were blocked by RN1734 and T1E3 in WT mice, but only by RN1734 in TRPC1-/- mice. Moreover, GSK activated cation channel activity with a 6pS conductance in WT ECs but with a 52 pS conductance in TRPC1-/- ECs. These results indicate that stimulation of CaSR activates heteromeric TRPV4/TRPC1 channels and NO production in ECs, which are responsible for endothelium-dependent vasorelaxations. This study also suggests that heteromeric TRPV4-TRPC1 channels may form the predominant TRPV4-containing channels in mouse mesenteric artery ECs. Together, our data further implicates CaSR-induced pathways and heteromeric TRPV4/TRPC1 channels in the regulation of vascular tone.
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Affiliation(s)
- Harry Z E Greenberg
- Vascular Biology Research Centre, Molecular & Clinical Sciences Research Institute, St. George's, University of London, London, UK
| | - Simonette R E Carlton-Carew
- Vascular Biology Research Centre, Molecular & Clinical Sciences Research Institute, St. George's, University of London, London, UK
| | - Alexander K Zargaran
- Vascular Biology Research Centre, Molecular & Clinical Sciences Research Institute, St. George's, University of London, London, UK
| | - Kazi S Jahan
- Vascular Biology Research Centre, Molecular & Clinical Sciences Research Institute, St. George's, University of London, London, UK
| | - Lutz Birnbaumer
- Laboratory of Neurobiology, National Institute of Environmental Health Sciences, Research Triangle Park, NC, USA.,Institute of Biomedical Research (BIOMED), Catholic University of Argentina, Buenos Aires, Argentina
| | - Anthony P Albert
- Vascular Biology Research Centre, Molecular & Clinical Sciences Research Institute, St. George's, University of London, London, UK
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Abstract
BACKGROUND Functional dyspepsia is a heterogeneous disorder lacking an established therapeutic strategy. Historical treatment attempts with pepsin products were shrugged off, as a simple calculation shows that quantitative substitution is pointless. However, such attempts might have been right for the wrong reason. SUMMARY Today, the role of pepsins is primarily seen in the provision of signalling amino acids (especially phenylalanine and tryptophan) and peptides, which initiate processes promoting digestion. Proteolysis benefits from pepsin variants showing, contrary to common belief, activities of up to a pH value of 5.0. Non-clinical and clinical studies support the view that liberated amino acids produce a variety of direct and indirect effects. Signal chains stimulated by (mostly aromatic) amino acids lead to secretion of gastrin and cholecystokinin (CCK), mediated, respectively, by CCK2 (gastrin) and Ca2+-sensing receptors in the parietal cell, and Ca2+-sensing receptors in the antral and duodenal mucosa. Thus, CCK effects such as secretion of pancreatic enzymes and promotion of gastric accommodation are (also) consequential to peptic liberation of amino acids. Key Message: As functional dyspepsia represents a heterogeneous disorder, it may be intriguing to view pepsin as a potential (although still to be proven) treatment modality, distinguished by a diversity of pro-digestive effects.
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Liu CH, Chang HK, Lee SP, Shieh RC. Activation of the Ca 2+-sensing receptors increases currents through inward rectifier K + channels via activation of phosphatidylinositol 4-kinase. Pflugers Arch 2016; 468:1931-43. [PMID: 27838849 DOI: 10.1007/s00424-016-1901-y] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/17/2016] [Revised: 10/26/2016] [Accepted: 11/06/2016] [Indexed: 10/25/2022]
Abstract
Inward rectifier K+ channels are important for maintaining normal electrical function in many cell types. The proper function of these channels requires the presence of membrane phosphoinositide 4,5-bisphosphate (PIP2). Stimulation of the Ca2+-sensing receptor CaR, a pleiotropic G protein-coupled receptor, activates both Gq/11, which decreases PIP2, and phosphatidylinositol 4-kinase (PI-4-K), which, conversely, increases PIP2. How membrane PIP2 levels are regulated by CaR activation and whether these changes modulate inward rectifier K+ are unknown. In this study, we found that activation of CaR by the allosteric agonist, NPSR568, increased inward rectifier K+ current (I K1) in guinea pig ventricular myocytes and currents mediated by Kir2.1 channels exogenously expressed in HEK293T cells with a similar sensitivity. Moreover, using the fluorescent PIP2 reporter tubby-R332H-cYFP to monitor PIP2 levels, we found that CaR activation in HEK293T cells increased membrane PIP2 concentrations. Pharmacological studies showed that both phospholipase C (PLC) and PI-4-K are activated by CaR stimulation with the latter played a dominant role in regulating membrane PIP2 and, thus, Kir currents. These results provide the first direct evidence that CaR activation upregulates currents through inward rectifier K+ channels by accelerating PIP2 synthesis. The regulation of I K1 plays a critical role in the stability of the electrical properties of many excitable cells, including cardiac myocytes and neurons. Further, synthetic allosteric modulators that increase CaR activity have been used to treat hyperparathyroidism, and negative CaR modulators are of potential importance in the treatment of osteoporosis. Thus, our results provide further insight into the roles played by CaR in the cardiovascular system and are potentially valuable for heart disease treatment and drug safety.
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Greenberg HZE, Shi J, Jahan KS, Martinucci MC, Gilbert SJ, Vanessa Ho WS, Albert AP. Stimulation of calcium-sensing receptors induces endothelium-dependent vasorelaxations via nitric oxide production and activation of IKCa channels. Vascul Pharmacol 2016; 80:75-84. [PMID: 26772767 PMCID: PMC4830458 DOI: 10.1016/j.vph.2016.01.001] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 12/09/2015] [Accepted: 01/02/2016] [Indexed: 11/25/2022]
Abstract
Stimulation of vascular calcium-sensing receptors (CaSRs) is reported to induce both constrictions and relaxations. However, cellular mechanisms involved in these responses remain unclear. The present study investigates the effect of stimulating CaSRs on vascular contractility and focuses on the role of the endothelium, nitric oxide (NO) and K(+) channels in these responses. In wire myography studies, increasing [Ca(2+)]o from 1mM to 6mM induced concentration-dependent relaxations of methoxamine pre-contracted rabbit mesenteric arteries. [Ca(2+)]o-induced relaxations were dependent on a functional endothelium, and were inhibited by the negative allosteric CaSR modulator Calhex-231. [Ca(2+)]o-induced relaxations were reduced by inhibitors of endothelial NO synthase, guanylate cyclase, and protein kinase G. CaSR activation also induced NO production in freshly isolated endothelial cells (ECs) in experiments using the fluorescent NO indicator DAF-FM. Pre-treatment with inhibitors of large (BKCa) and intermediate (IKCa) Ca(2+)-activated K(+) channels (iberiotoxin and charybdotoxin), and Kv7 channels (linopirdine) also reduced [Ca(2+)]o-induced vasorelaxations. Increasing [Ca(2+)]o also activated IKCa currents in perforated-patch recordings of isolated mesenteric artery ECs. These findings indicate that stimulation of CaSRs induces endothelium-dependent vasorelaxations which are mediated by two separate pathways involving production of NO and activation of IKCa channels. NO stimulates PKG leading to BKCa activation in vascular smooth muscle cells, whereas IKCa activity contributes to endothelium-derived hyperpolarisations.
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Affiliation(s)
- Harry Z E Greenberg
- Vascular Biology Research Centre, Institute of Cardiovascular & Cell Sciences, St. George's, University of London, Cranmer Terrace, London SW17 0RE, UK.
| | - Jian Shi
- Vascular Biology Research Centre, Institute of Cardiovascular & Cell Sciences, St. George's, University of London, Cranmer Terrace, London SW17 0RE, UK
| | - Kazi S Jahan
- Vascular Biology Research Centre, Institute of Cardiovascular & Cell Sciences, St. George's, University of London, Cranmer Terrace, London SW17 0RE, UK
| | - Matthew C Martinucci
- Vascular Biology Research Centre, Institute of Cardiovascular & Cell Sciences, St. George's, University of London, Cranmer Terrace, London SW17 0RE, UK
| | - Steven J Gilbert
- Vascular Biology Research Centre, Institute of Cardiovascular & Cell Sciences, St. George's, University of London, Cranmer Terrace, London SW17 0RE, UK
| | - W-S Vanessa Ho
- Vascular Biology Research Centre, Institute of Cardiovascular & Cell Sciences, St. George's, University of London, Cranmer Terrace, London SW17 0RE, UK
| | - Anthony P Albert
- Vascular Biology Research Centre, Institute of Cardiovascular & Cell Sciences, St. George's, University of London, Cranmer Terrace, London SW17 0RE, UK
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Wang P, Wang L, Wang S, Li S, Li Y, Zhang L. Effects of calcium-sensing receptors on apoptosis in rat hippocampus during hypoxia/reoxygenation through the ERK1/2 pathway. Int J Clin Exp Pathol 2015; 8:10808-10815. [PMID: 26617793 PMCID: PMC4637608] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 06/26/2015] [Indexed: 06/05/2023]
Abstract
OBJECTIVES To explore the effects of calcium-sensing receptors (CaSR) on apoptosis in rat hippocampus during hypoxia/reoxygenation (H/R). METHODS After rat hippocampus was isolated, the cultures were subjected to H/R, and meanwhile gadolinium chloride (GdCl3, agonist of CaSR) and NPS 2390 (antagonists of CaSR) were added to reperfusion solution. The number of hippocampal neuron, cell viability and apoptosis rate were determined by inverted microscope, 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) and flow cytometer (FCM), respectively. Besides, caspase-3, Bax, cytochrome C (Cyt-c), extracellular signal-regulated protein kinase (ERK) 1/2, pERK1/2, P38 and pP38 were analyzed by Western blotting. RESULTS The hippocampal neuron number and cell viability were significantly decreased during H/R, and were further significantly reduced when co-treatment with CaSR agonist GdCl3. But the effects of GdCl3 were attenuated by NPS-2390. Whereas, apoptosis rate, the expression level of caspase-3, Bax and Cyt-c were all significantly increased under H/R condition, and was further significantly increased by GdCl3, but were reversed by NPS-2390 (P < 0.05). Moreover, there were no significant differences in expression of ERK1/2, P38 and pP38 among different groups. However, the expression of pERK1/2 was significantly increased during H/R, but was significantly reduced by NPS 2390 (P < 0.05). CONCLUSION The results suggest that CaSR might play significant roles in the induction of hippocampus apoptosis in rat during H/R through phosphorylation of ERK1/2.
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Affiliation(s)
- Peng Wang
- Department of Anesthesiology, Affiliated Hospital of Qingdao University Qingdao, Shandong, P. R. China
| | - Li Wang
- Department of Anesthesiology, Affiliated Hospital of Qingdao University Qingdao, Shandong, P. R. China
| | - Shilei Wang
- Department of Anesthesiology, Affiliated Hospital of Qingdao University Qingdao, Shandong, P. R. China
| | - Shuhong Li
- Department of Anesthesiology, Affiliated Hospital of Qingdao University Qingdao, Shandong, P. R. China
| | - Yu Li
- Department of Anesthesiology, Affiliated Hospital of Qingdao University Qingdao, Shandong, P. R. China
| | - Lin Zhang
- Department of Anesthesiology, Affiliated Hospital of Qingdao University Qingdao, Shandong, P. R. China
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Wang P, Wang L, Wang S, Li S, Li Y, Zhang L. Effects of calcium-sensing receptors on apoptosis in rat hippocampus during hypoxia/re-oxygenation through the ERK1/2 pathway. Int J Clin Exp Med 2015; 8:12858-12865. [PMID: 26550201 PMCID: PMC4612886] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/20/2015] [Accepted: 06/21/2015] [Indexed: 06/05/2023]
Abstract
OBJECTIVES To explore the effects of calcium-sensing receptors (CaSR) on apoptosis in rat hippocampus during hypoxia/re-oxygenation (H/R). METHODS After post-culturing of isolated rat hippocampus, the cultures were subjected to H/R, meanwhile gadolinium chloride (GdCl3, agonist of CaSR) and NPS 2390 (antagonists of CaSR) was added to reperfusion solution. The number of hippocampal neuron, cell proliferation assay and apoptosis rate was determined by inverted microscope, 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) and flow cytometer (FCM). Besides, caspase-3, Bax, cytochrome C (Cyt-c), extracellular signal-regulated protein kinase (ERK) 1/2, pERK1/2, P38 and pP38 were analyzed by western blotting. RESULTS The hippocampal neuron number and cell viability were significantly decreased after H/R treatment, and were further significantly reduced when co-treatment with CaSR agonist GdCl3. But the effects of GdCl3 were attenuated by NPS-2390. Whereas, apoptosis rate, the expression level of caspase-3, Bax and Cyt-c were all significantly increased under H/R condition, and was further significantly increased by GdCl3, but were reversed by NPS-2390 (P < 0.05). Moreover, there were no significant differences in expression of ERK1/2, P38 and pP38 among different groups. However, the expression of pERK1/2 was significantly increased after H/R treatment, but was significantly reduced by NPS 2390 (P < 0.05). CONCLUSION The results suggest that CaSR might play significant roles in the induction of hippocampus apoptosis in rat during H/R through phosphorylation of ERK1/2.
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Affiliation(s)
- Peng Wang
- Department of Anesthesiology, Affiliated Hospital of Qingdao University Qingdao, Shandong, P.R. China
| | - Li Wang
- Department of Anesthesiology, Affiliated Hospital of Qingdao University Qingdao, Shandong, P.R. China
| | - Shilei Wang
- Department of Anesthesiology, Affiliated Hospital of Qingdao University Qingdao, Shandong, P.R. China
| | - Shuhong Li
- Department of Anesthesiology, Affiliated Hospital of Qingdao University Qingdao, Shandong, P.R. China
| | - Yu Li
- Department of Anesthesiology, Affiliated Hospital of Qingdao University Qingdao, Shandong, P.R. China
| | - Lin Zhang
- Department of Anesthesiology, Affiliated Hospital of Qingdao University Qingdao, Shandong, P.R. China
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Choi KH, Shin CH, Yang SW, Cheong HI. Autosomal dominant hypocalcemia with Bartter syndrome due to a novel activating mutation of calcium sensing receptor, Y829C. Korean J Pediatr 2015; 58:148-53. [PMID: 25932037 PMCID: PMC4414630 DOI: 10.3345/kjp.2015.58.4.148] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 09/15/2013] [Revised: 10/15/2013] [Accepted: 10/21/2013] [Indexed: 11/27/2022]
Abstract
The calcium sensing receptor (CaSR) plays an important role in calcium homeostasis. Activating mutations of CaSR cause autosomal dominant hypocalcemia by affecting parathyroid hormone secretion in parathyroid gland and calcium resorption in kidney. They can also cause a type 5 Bartter syndrome by inhibiting the apical potassium channel in the thick ascending limb of the loop of Henle in the kidney. This study presents a patient who had autosomal dominant hypocalcemia with Bartter syndrome due to an activating mutation Y829C in the transmembrane domain of the CaSR. Symptoms of hypocalcemia occurred 12 days after birth and medication was started immediately. Medullary nephrocalcinosis and basal ganglia calcification were found at 7 years old and at 17 years old. Three hypercalcemic episodes occurred, one at 14 years old and two at 17 years old. The Bartter syndrome was not severe while the serum calcium concentration was controlled, but during hypercalcemic periods, the symptoms of Bartter syndrome were aggravated.
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Affiliation(s)
- Keun Hee Choi
- Department of Pediatrics, Seoul National University Children's Hospital, Seoul, Korea
| | - Choong Ho Shin
- Division of Endocrinology and Metabolism, Department of Pediatrics, Seoul National University Children's Hospital, Seoul, Korea
| | - Sei Won Yang
- Division of Endocrinology and Metabolism, Department of Pediatrics, Seoul National University Children's Hospital, Seoul, Korea
| | - Hae Il Cheong
- Department of Pediatrics, Seoul National University Children's Hospital, Seoul, Korea. ; Research Coordination Center for Rare Diseases, Seoul National University Hospital, Seoul, Korea. ; Kidney Research Institute, Medical Research Center, Seoul National University College of Medicine, Seoul, Korea
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