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New Insights into the Regulation of mTOR Signaling via Ca 2+-Binding Proteins. Int J Mol Sci 2023; 24:ijms24043923. [PMID: 36835331 PMCID: PMC9959742 DOI: 10.3390/ijms24043923] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Revised: 02/09/2023] [Accepted: 02/13/2023] [Indexed: 02/17/2023] Open
Abstract
Environmental factors are important regulators of cell growth and proliferation. Mechanistic target of rapamycin (mTOR) is a central kinase that maintains cellular homeostasis in response to a variety of extracellular and intracellular inputs. Dysregulation of mTOR signaling is associated with many diseases, including diabetes and cancer. Calcium ion (Ca2+) is important as a second messenger in various biological processes, and its intracellular concentration is tightly regulated. Although the involvement of Ca2+ mobilization in mTOR signaling has been reported, the detailed molecular mechanisms by which mTOR signaling is regulated are not fully understood. The link between Ca2+ homeostasis and mTOR activation in pathological hypertrophy has heightened the importance in understanding Ca2+-regulated mTOR signaling as a key mechanism of mTOR regulation. In this review, we introduce recent findings on the molecular mechanisms of regulation of mTOR signaling by Ca2+-binding proteins, particularly calmodulin (CaM).
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Deletion of Notch3 Impairs Contractility of Renal Resistance Vessels Due to Deficient Ca 2+ Entry. Int J Mol Sci 2022; 23:ijms232416068. [PMID: 36555708 PMCID: PMC9788231 DOI: 10.3390/ijms232416068] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/19/2022] [Revised: 12/09/2022] [Accepted: 12/13/2022] [Indexed: 12/23/2022] Open
Abstract
Notch3 plays an important role in the differentiation and development of vascular smooth muscle cells. Mice lacking Notch3 show deficient renal autoregulation. The aim of the study was to investigate the mechanisms involved in the Notch3-mediated control of renal vascular response. To this end, renal resistance vessels (afferent arterioles) were isolated from Notch3-/- and wild-type littermates (WT) and stimulated with angiotensin II (ANG II). Contractions and intracellular Ca2+ concentrations were blunted in Notch3-/- vessels. ANG II responses in precapillary muscle arterioles were similar between the WT and Notch3-/- mice, suggesting a focal action of Notch3 in renal vasculature. Abolishing stored Ca2+ with thapsigargin reduced Ca2+ responses in the renal vessels of the two strains, signifying intact intracellular Ca2+ mobilization in Notch3-/-. EGTA (Ca2+ chelating agent), nifedipine (L-type channel-blocker), or mibefradil (T-type channel-blocker) strongly reduced contraction and Ca2+ responses in WT mice but had no effect in Notch3-/- mice, indicating defective Ca2+ entry. Notch3-/- vessels responded normally to KCl-induced depolarization, which activates L-type channels directly. Differential transcriptomic analysis showed a major down-regulation of Cacna1h gene expression, coding for the α1H subunit of the T-type Ca2+ channel, in Notch3-/- vessels. In conclusion, renal resistance vessels from Notch3-/- mice display altered vascular reactivity to ANG II due to deficient Ca2+-entry. Consequently, Notch3 is essential for proper excitation-contraction coupling and vascular-tone regulation in the kidney.
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WIN55212-2 Modulates Intracellular Calcium via CB 1 Receptor-Dependent and Independent Mechanisms in Neuroblastoma Cells. Cells 2022; 11:2947. [PMID: 36230909 PMCID: PMC9563019 DOI: 10.3390/cells11192947] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2022] [Revised: 09/13/2022] [Accepted: 09/16/2022] [Indexed: 11/29/2022] Open
Abstract
The CB1 cannabinoid receptor (CB1R) and extracellular calcium (eCa2+)-stimulated Calcium Sensing receptor (CaSR) can exert cellular signaling by modulating levels of intracellular calcium ([Ca2+]i). We investigated the mechanisms involved in the ([Ca2+]i) increase in N18TG2 neuroblastoma cells, which endogenously express both receptors. Changes in [Ca2+]i were measured in cells exposed to 0.25 or 2.5 mM eCa2+ by a ratiometric method (Fura-2 fluorescence) and expressed as the difference between baseline and peak responses (ΔF340/380). The increased ([Ca2+]i) in cells exposed to 2.5 mM eCa2+ was blocked by the CaSR antagonist, NPS2143, this inhibition was abrogated upon stimulation with WIN55212-2. WIN55212-2 increased [Ca2+]i at 0.25 and 2.5 mM eCa2+ by 700% and 350%, respectively, but this increase was not replicated by CP55940 or methyl-anandamide. The store-operated calcium entry (SOCE) blocker, MRS1845, attenuated the WIN55212-2-stimulated increase in [Ca2+]i at both levels of eCa2+. Simultaneous perfusion with the CB1 antagonist, SR141716 or NPS2143 decreased the response to WIN55212-2 at 0.25 mM but not 2.5 mM eCa2+. Co-perfusion with the non-CB1/CB2 antagonist O-1918 attenuated the WIN55212-2-stimulated [Ca2+]i increase at both eCa2+ levels. These results are consistent with WIN55212-2-mediated intracellular Ca2+ mobilization from store-operated calcium channel-filled sources that could occur via either the CB1R or an O-1918-sensitive non-CB1R in coordination with the CaSR. Intracellular pathway crosstalk or signaling protein complexes may explain the observed effects.
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Expression Pattern of Purinergic Signaling Components in Colorectal Cancer Cells and Differential Cellular Outcomes Induced by Extracellular ATP and Adenosine. Int J Mol Sci 2021; 22:ijms222111472. [PMID: 34768902 PMCID: PMC8583864 DOI: 10.3390/ijms222111472] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/07/2021] [Revised: 10/19/2021] [Accepted: 10/20/2021] [Indexed: 12/23/2022] Open
Abstract
The purine nucleotide adenosine triphosphate (ATP) is known for its fundamental role in cellular bioenergetics. However, in the last decades, different works have described emerging functions for ATP, such as that of a danger signaling molecule acting in the extracellular space on both tumor and stromal compartments. Beside its role in immune cell signaling, several studies have shown that high concentrations of extracellular ATP can directly or indirectly act on cancer cells. Accordingly, it has been reported that purinergic receptors are widely expressed in tumor cells. However, their expression pattern is often associated with contradictory cellular outcomes. In this work, we first investigated gene expression profiles through "RNA-Sequencing" (RNA Seq) technology in four colorectal cancer (CRC) cell lines (HT29, LS513, LS174T, HCT116). Our results demonstrate that CRC cells mostly express the A2B, P2X4, P2Y1, P2Y2 and P2Y11 purinergic receptors. Among these, the P2Y1 and P2Y2 coding genes are markedly overexpressed in all CRC cells compared to the HCEC-1CT normal-like colonic cells. We then explored the cellular outcomes induced by extracellular ATP and adenosine. Our results show that in terms of cell death induction extracellular ATP is consistently more active than adenosine against CRC, while neither compound affected normal-like colonic cell survival. Intriguingly, while for the P2Y2 receptor pharmacological inhibition completely abolished the rise in cytoplasmic Ca2+ observed after ATP exposure in all CRC cell lines, Ca2+ mobilization only impacted the cellular outcome for HT29. In contrast, non-selective phosphodiesterase inhibition completely abolished the effects of extracellular ATP on CRC cells, suggesting that cAMP and/or cGMP levels might determine cellular outcome. Altogether, our study provides novel insights into the characterization of purinergic signaling in CRC.
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Abstract
Objective: Interleukin (IL)-33 has been attracting more and more attention as a new member of theIL-1 cytokine family in recent years. However, the underlying mechanisms referred to the regulation of endogenous IL-33 production are not fully illustrated. Paeoniflorin (PF) has been reported to possess multiple pharmacological activities, including anti-inflammation and anti-allergy. In this study, we aimed to investigate the effect of PF on IL-33 production by macrophages and explore the underlying mechanisms.Methods: In vivo, IL-33 production in mice after lipopolysaccharide (LPS) injection together with PF application was detected by enzyme-linked immunosorbent assay (ELISA). In vitro, MTT, Real-time PCR, ELISA, Calcium (Ca2+) imaging and Western blot were used to assess the cytotoxicity of PF, IL-33 expression at mRNA and protein levels, Ca2+ influx, protein kinase C (PKC) activity, nuclear factor-kappa B (NF-κB), and mitogen-activated protein kinase (MAPK) activation in LPS-stimulated RAW264.7 macrophages with PF administration.Results: Our results indicated that PF (5 and 25 mg/kg) significantly reduced the production of TNF-a, IL-1β, and IL-33 in the peritoneal exudate of LPS-treated mice. In vitro assay, upregulation of PF concentration (≥ 20 μM) showed an increased cytotoxicity in RAW264.7 cells during the 24-h cell culture. PF (10 μM) inhibited IL-33 production, Ca2+ influx, PKC activity, NF-κB (p65) activation, and P38MAPK phosphorylation in LPS-treated macrophages. Notably, NF-κB inhibitor (BAY 11-7085), P38MAPK inhibitor (SB203580), and Ca2+ blocker (NiCl2) also curbed LPS-induced IL-33 production, respectively.Conclusions: PF suppresses IL-33 production by macrophages via inhibiting NF-κB and P38MAPK activation associated with the regulation of Ca2+ mobilization.
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Aquaporin 8 is involved in H 2 O 2 -mediated differential regulation of metabolic signaling by α 1 - and β-adrenoceptors in hepatocytes. FEBS Lett 2020; 594:1564-1576. [PMID: 32115689 DOI: 10.1002/1873-3468.13763] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Revised: 01/16/2020] [Accepted: 02/12/2020] [Indexed: 12/20/2022]
Abstract
Reactive oxygen species participate in regulating intracellular signaling pathways. Herein, we investigated the reported opposite effects of hydrogen peroxide (H2 O2 ) on metabolic signaling mediated by activated α1 - and β-adrenoceptors (ARs) in hepatocytes. In isolated rat hepatocytes, stimulation of α1 -AR increases H2 O2 production via NADPH oxidase 2 (NOX2) activation. We find that the H2 O2 thus produced is essential for α1 -AR-mediated activation of the classical hepatic glycogenolytic, gluconeogenic, and ureagenic responses. However, H2 O2 inhibits β-AR-mediated activation of these metabolic responses. We show that H2 O2 mediates its effects on α1 -AR and β-AR by permeating cells through aquaporin 8 (AQP8) channels and promoting Ca2+ mobilization. Thus, our findings reveal a novel NOX2-H2 O2 -AQP8-Ca2+ signaling cascade acting downstream of α1 -AR in hepatocytes, which, by negatively regulating β-AR signaling, establishes negative crosstalk between the two pathways.
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Intracellular Ca 2+ mobilization pathway via bradykinin B 1 receptor activation in rat trigeminal ganglion neurons. J Physiol Sci 2019; 69:199-209. [PMID: 30182285 PMCID: PMC10717581 DOI: 10.1007/s12576-018-0635-3] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2018] [Accepted: 08/20/2018] [Indexed: 10/28/2022]
Abstract
Bradykinin (BK) and its receptors, B1 and B2, in trigeminal ganglion (TG) neurons are involved in the regulation of pain. Recent studies have revealed that B1 receptors are expressed in neonatal rat TG neurons; however, the intracellular signaling pathway following B1 receptor activation remains to be elucidated. To investigate the mechanism by which B1 receptor activation leads to intracellular Ca2+ mobilization, we measured the intracellular free Ca2+ concentration ([Ca2+]i) in primary-cultured TG neurons. The application of Lys-[Des-Arg9]BK (B1 receptor agonist) increased the [Ca2+]i in these TG neurons even in the absence of extracellular Ca2+. Pretreatment with inhibitors of ryanodine receptors or sarco/endoplasmic reticulum Ca2+-ATPase suppressed the increase in Lys-[Des-Arg9]BK-induced [Ca2+]i. The Lys-[Des-Arg9]BK-induced [Ca2+]i increase was unaffected by phospholipase-C inhibitor. B1 receptor activation-induced [Ca2+]i increase was suppressed by phosphodiesterase inhibitor and enhanced by adenylyl cyclase inhibitor. These results suggest that B1 receptor activation suppresses intracellular cAMP production via adenylyl cyclase inhibition and mobilizes intracellular Ca2+ via ryanodine receptors that access intracellular Ca2+ stores.
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Restricted cell functions on micropillars are alleviated by surface-nanocoating with amino groups. J Cell Sci 2018; 131:jcs.207001. [PMID: 29122983 DOI: 10.1242/jcs.207001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2017] [Accepted: 11/05/2017] [Indexed: 01/13/2023] Open
Abstract
The topographical and chemical surface features of biomaterials are sensed by the cells, affecting their physiology at the interface. When placed on titanium, we recently discovered osteoblasts attempted caveolae-mediated phagocytosis of the sharp-edged microstructures. This active, energy-consuming process resulted in decreased osteoblastic cell functions (e.g. secretion of extracellular matrix proteins). However, chemical modification with plasma polymerized allylamine (PPAAm) was able to amplify osteoblast adhesion and spreading, resulting in better implant osseointegration in vivo In the present in vitro study, we analyzed whether this plasma polymer nanocoating is able to attenuate the microtopography-induced changes of osteoblast physiology. On PPAAm, we found cells showed a higher cell interaction with the geometrical micropillars by 30 min, and a less distinct reduction in the mRNA expression of collagen type I, osteocalcin and fibronectin after 24 h of cell growth. Interestingly, the cells were more active and sensitive on PPAAm-coated micropillars, and react with a substantial Ca2+ ion mobilization after stimulation with ATP. These results highlight that it is important for osteoblasts to establish cell surface contact for them to perform their functions.
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What goes up must come down: A tripartite Dok-3/Grb2/SHIP1 inhibitory module limits BCR signaling. Eur J Immunol 2017; 46:2507-2511. [PMID: 27813071 DOI: 10.1002/eji.201646705] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2016] [Revised: 09/20/2016] [Accepted: 09/27/2016] [Indexed: 01/30/2023]
Abstract
Properly regulated immunity requires precise integration of activating and inhibitory signals. As for other lymphocytes, B cells express an antigen-specific activating receptor, the B-cell antigen receptor (BCR), and inhibitory receptors (e.g. FcγRIIb) that exercise checkpoint control on B-cell activation. Moreover, following BCR engagement, CD19 recruits proteins that amplify BCR signaling, while CD22 initiates a negative feedback loop by recruiting proteins that inhibit BCR signaling. Initial BCR signaling is mediated by protein tyrosine kinases and lipid kinases; inhibitory receptors directly antagonize the actions of these enzymes by recruiting protein tyrosine phosphatases and lipid phosphatases and positioning them close to actively signaling BCRs. Previously it was thought that inhibitory receptors such as FcγRIIb and CD22 were essential for bringing these phosphatases near the BCR. In this issue of the European Journal of Immunology, Manno et al. show that a tripartite inhibitory module consisting of the adaptor proteins Dok-3 and Grb2 and the lipid phosphatase SHIP1 binds directly to activated BCRs and limits the Ca2+ mobilization that is required for B lymphocyte activation. This reveals that the BCR can be both an activating and inhibitory receptor, one that activates signaling enzymes while initiating a negative feedback loop that prevents excessive signaling.
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Tumor necrosis factor regulates NMDA receptor-mediated airway smooth muscle contractile function and airway responsiveness. Am J Physiol Lung Cell Mol Physiol 2016; 311:L467-80. [PMID: 27371735 DOI: 10.1152/ajplung.00382.2015] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2015] [Accepted: 06/30/2016] [Indexed: 12/25/2022] Open
Abstract
We have shown that N-methyl-d-aspartate receptors (NMDA-Rs) are receptor-operated calcium entry channels in human airway smooth muscle (HASM) during contraction. Tumor necrosis factor (TNF) augments smooth muscle contractility by influencing pathways that regulate intracellular calcium flux and can alter NMDA-R expression and activity in cortical neurons and glial cells. We hypothesized that NMDA-R-mediated Ca(2+) and contractile responses of ASM can be altered by inflammatory mediators, including TNF. In cultured HASM cells, we assessed TNF (10 ng/ml, 48 h) effect on NMDA-R subunit abundance by quantitative PCR, confocal imaging, and immunoblotting. We observed dose- and time-dependent changes in NMDA-R composition: increased obligatory NR1 subunit expression and altered regulatory NR2 and inhibitory NR3 subunits. Measuring intracellular Ca(2+) flux in Fura-2-loaded HASM cultures, we observed that TNF exposure enhanced cytosolic Ca(2+) mobilization and changed the temporal pattern of Ca(2+) flux in individual myocytes induced by NMDA, an NMDA-R selective analog of glutamate. We measured airway responses to NMDA in murine thin-cut lung slices (TCLS) from allergen-naive animals and observed significant airway contraction. However, NMDA acted as a bronchodilator in TCLS from house dust mice-challenged mice and in allergen-naive TCLS subjected to TNF exposure. All contractile or bronchodilator responses were blocked by a selective NMDA-R antagonist, (2R)-amino-5-phosphonopentanoate, and bronchodilator responses were prevented by N(G)-nitro-l-arginine methyl ester (nitric oxide synthase inhibitor) or indomethacin (cyclooxygenase inhibitor). Collectively, we show that TNF augments NMDA-R-mediated Ca(2+) mobilization in HASM cells, whereas in multicellular TCLSs allergic inflammation and TNF exposure leads to NMDA-R-mediated bronchodilation. These findings reveal the unique contribution of ionotrophic NMDA-R to airway hyperreactivity.
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Modeling analysis of inositol 1,4,5-trisphosphate receptor-mediated Ca2+ mobilization under the control of glucagon-like peptide-1 in mouse pancreatic β-cells. Am J Physiol Cell Physiol 2016; 310:C337-47. [PMID: 26741144 PMCID: PMC4888524 DOI: 10.1152/ajpcell.00234.2015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/10/2015] [Accepted: 11/19/2015] [Indexed: 01/22/2023]
Abstract
Glucagon-like peptide-1 (GLP-1) is an intestinally derived blood glucose-lowering hormone that potentiates glucose-stimulated insulin secretion from pancreatic β-cells. The secretagogue action of GLP-1 is explained, at least in part, by its ability to stimulate cAMP production so that cAMP may facilitate the release of Ca(2+) from inositol trisphosphate receptor (IP3R)-regulated Ca(2+) stores. However, a quantitative model has yet to be provided that explains the molecular mechanisms and dynamic processes linking GLP-1-stimulated cAMP production to Ca(2+) mobilization. Here, we performed simulation studies to investigate how GLP-1 alters the abilities of Ca(2+) and IP3 to act as coagonists at IP3R Ca(2+) release channels. A new dynamic model was constructed based on the Kaftan model, which demonstrates dual steady-state allosteric regulation of the IP3R by Ca(2+) and IP3. Data obtained from β-cells were then analyzed to understand how GLP-1 facilitates IP3R-mediated Ca(2+) mobilization when UV flash photolysis is used to uncage Ca(2+) and IP3 intracellularly. When the dynamic model for IP3R activation was incorporated into a minimal cell model, the Ca(2+) transients and oscillations induced by GLP-1 were successfully reconstructed. Simulation studies indicated that transient and oscillatory responses to GLP-1 were produced by sequential positive and negative feedback regulation due to fast activation and slow inhibition of the IP3R by Ca(2+). The slow rate of Ca(2+)-dependent inhibition was revealed to provide a remarkable contribution to the time course of the decay of cytosolic Ca(2+) transients. It also served to drive and pace Ca(2+) oscillations that are significant when evaluating how GLP-1 stimulates insulin secretion.
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Inhibitory effect of acteoside on melittin-induced catecholamine exocytosis through inhibition of Ca(2+)-dependent phospholipase A2 and extracellular Ca(2+) influx in PC12 cells. Arch Pharm Res 2015; 38:1913-20. [PMID: 25899996 DOI: 10.1007/s12272-015-0601-z] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2014] [Accepted: 04/06/2015] [Indexed: 01/12/2023]
Abstract
To investigate the inhibitory effect of acteoside on the process of exocytosis induced by melittin, we measured Ca(2+) mobilization, arachidonic acid (AA) release and catecholamine exocytosis in PC12 chromaffin cells. Melittin significantly increased the intracellular Ca(2+) mobilization via receptor-operated calcium channel but not the intracellular Ca(2+) release. It caused AA release via activation of Ca(2+)-dependent phospholipase A2 (PLA2) and catecholamine secretion in a dose-dependent manner. Acteoside dose-dependently inhibited the release of AA and intracellular Ca(2+) mobilization induced by melittin. Acteoside reduced the catecholamine release and raised the amount of intracellular chromogranin A which is co-released with catecholamine from melittin-stimulated PC12 cells. Taken together, our results suggest that acteoside could suppress the exocytosis via inhibition of Ca(2+)-dependent PLA2 and extracellular Ca(2+) influx in PC12 cells stimulated by melittin.
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NMDA receptors mediate contractile responses in human airway smooth muscle cells. Am J Physiol Lung Cell Mol Physiol 2015; 308:L1253-64. [PMID: 25888577 DOI: 10.1152/ajplung.00402.2014] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/22/2014] [Accepted: 04/15/2015] [Indexed: 01/12/2023] Open
Abstract
Human airway smooth muscle (HASM) exhibits enhanced contractility in asthma. Inflammation is associated with airway hypercontractility, but factors that underpin these features are not fully elucidated. Glutamate toxicity associated with increased plasma glutamate concentrations was observed in airway inflammation, suggesting that multisubunit glutamate receptors, N-methyl-d-aspartate receptors (NMDA-R) contribute to airway hyperreactivity. We tested the hypothesis that HASM expresses NMDA-R subunits that can form functional receptors to mediate contractile responses to specific extracellular ligands. In cultured HASM cells, we measured NMDA-R subunit mRNA and protein abundance by quantitative PCR, immunoblotting, flow cytometry, and epifluorescence immunocytochemistry. We measured mRNA for a number of NMDA-R subunits, including the obligatory NR1 subunit, which we confirmed to be present as a protein. In vitro and ex vivo functional NMDA-R activation in HASM cells was measured using intracellular calcium flux (fura-2 AM), collagen gel contraction assays, and murine thin-cut lung slices (TCLS). NMDA, a pharmacological glutamate analog, induced cytosolic calcium mobilization in cultured HASM cells. We detected three different temporal patterns of calcium response, suggesting the presence of heterogeneous myocyte subpopulations. NMDA-R activation also induced airway contraction in murine TCLS and soft collagen gels seeded with HASM cells. Responses in cells, lung slices, and collagen gels were mediated by NMDA-R, as they could be blocked by (2R)-amino-5-phosphonopentanoate, a specific NMDA-R inhibitor. In summary, we reveal the presence of NMDA-R in HASM that mediate contractile responses via glutamatergic mechanisms. These findings suggest that accumulation of glutamate-like ligands for NMDA-R associated with airway inflammation contributes directly to airway hyperreactivity.
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Effects of C18 Fatty Acids on Intracellular Ca(2+) Mobilization and Histamine Release in RBL-2H3 Cells. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2014; 18:241-7. [PMID: 24976764 PMCID: PMC4071177 DOI: 10.4196/kjpp.2014.18.3.241] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 02/19/2014] [Revised: 03/20/2014] [Accepted: 04/23/2014] [Indexed: 11/15/2022]
Abstract
To investigate the underlying mechanisms of C18 fatty acids (stearic acid, oleic acid, linoleic acid and α-linolenic acid) on mast cells, we measured the effect of C18 fatty acids on intracellular Ca2+ mobilization and histamine release in RBL-2H3 mast cells. Stearic acid rapidly increased initial peak of intracellular Ca2+ mobilization, whereas linoleic acid and α-linolenic acid gradually increased this mobilization. In the absence of extracellular Ca2+, stearic acid (100 µM) did not cause any increase of intracellular Ca2+ mobilization. Both linoleic acid and α-linolenic acid increased intracellular Ca2+ mobilization, but the increase was smaller than that in the presence of extracellular Ca2+. These results suggest that C18 fatty acid-induced intracellular Ca2+ mobilization is mainly dependent on extracellular Ca2+ influx. Verapamil dose-dependently inhibited stearic acid-induced intracellular Ca2+ mobilization, but did not affect both linoleic acid and α-linolenic acid-induced intracellular Ca2+ mobilization. These data suggest that the underlying mechanism of stearic acid, linoleic acid and α-linolenic acid on intracellular Ca2+ mobilization may differ. Linoleic acid and α-linolenic acid significantly increased histamine release. Linoleic acid (C18:2: ω-6)-induced intracellular Ca2+ mobilization and histamine release were more prominent than α-linolenic acid (C18:3: ω-3). These data support the view that the intake of more α-linolenic acid than linoleic acid is useful in preventing inflammation.
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Abstract
Cell signaling is an essential requirement for mammalian cell invasion by Trypanosoma cruzi. Depending on the parasite strain and the parasite developmental form, distinct signaling pathways may be induced. In this short review, we focus on the data coming from studies with metacyclic trypomastigotes (MT) generated in vitro and tissue culture-derived trypomastigotes (TCT), used as counterparts of insect-borne and bloodstream parasites, respectively. During invasion of host cells by MT or TCT, intracellular Ca2+ mobilization and host cell lysosomal exocytosis are triggered. Invasion mediated by MT surface molecule gp82 requires the activation of mammalian target of rapamycin (mTOR), phosphatidylinositol 3-kinase (PI3K), and protein kinase C (PKC) in the host cell, associated with Ca2+-dependent disruption of the actin cytoskeleton. In MT, protein tyrosine kinase, PI3K, phospholipase C, and PKC appear to be activated. TCT invasion, on the other hand, does not rely on mTOR activation, rather on target cell PI3K, and may involve the host cell autophagy for parasite internalization. Enzymes, such as oligopeptidase B and the major T. cruzi cysteine proteinase cruzipain, have been shown to generate molecules that induce target cell Ca2+ signal. In addition, TCT may trigger host cell responses mediated by transforming growth factor β receptor or integrin family member. Further investigations are needed for a more complete and detailed picture of T. cruzi invasion.
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Intracellular Ca Mobilization and Beta-hexosaminidase Release Are Not Influenced by 60 Hz-electromagnetic Fields (EMF) in RBL 2H3 Cells. THE KOREAN JOURNAL OF PHYSIOLOGY & PHARMACOLOGY : OFFICIAL JOURNAL OF THE KOREAN PHYSIOLOGICAL SOCIETY AND THE KOREAN SOCIETY OF PHARMACOLOGY 2011; 15:313-7. [PMID: 22128265 DOI: 10.4196/kjpp.2011.15.5.313] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/11/2011] [Revised: 10/15/2011] [Accepted: 10/21/2011] [Indexed: 11/15/2022]
Abstract
The effects of extremely low frequency electromagnetic fields (EMF) on intracellular Ca(2+) mobilization and cellular function in RBL 2H3 cells were investigated. Exposure to EMF (60 Hz, 0.1 or 1 mT) for 4 or 16 h did not produce any cytotoxic effects in RBL 2H3 cells. Melittin, ionomycin and thapsigargin each dose-dependently increased the intracellular Ca(2+) concentration. The increase of intracellular Ca(2+) induced by these three agents was not affected by exposure to EMF (60 Hz, 1 mT) for 4 or 16 h in RBL 2H3 cells. To investigate the effect of EMF on exocytosis, we measured beta-hexosaminidase release in RBL 2H3 cells. Basal release of beta-hexosaminidase was 12.3±2.3% in RBL 2H3 cells. Exposure to EMF (60 Hz, 0.1 or 1 mT) for 4 or 16 h did not affect the basal or 1 µM melittin-induced beta-hexosaminidase release in RBL 2H3 cells. This study suggests that exposure to EMF (60 Hz, 0.1 or 1 mT), which is the limit of occupational exposure, has no influence on intracellular Ca(2+) mobilization and cellular function in RBL 2H3 cells.
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Two-pore channels for integrative Ca signaling. Commun Integr Biol 2011; 3:12-7. [PMID: 20539775 DOI: 10.4161/cib.3.1.9793] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2009] [Accepted: 08/12/2009] [Indexed: 11/19/2022] Open
Abstract
Two-pore channels (TPCs) are related to voltage-gated Ca(2+) and Na(+) channels. They most likely work as dimers with each of the two TPC protein subunits containing two pore-forming domains. Recent studies suggest that TPCs are expressed on the membranes of endosomes and lysosomes where they form receptors for nicotinic acid adenine dinucleotide phosphate (NAADP), the most potent Ca(2+) mobilizing messenger inside cells. Upon activation by NAADP, Ca(2+) release from endolysosomal stores through TPCs triggers cytoplasmic Ca(2+) signals. Because of discrete localizations of these acidic vesicles and their small, albeit variable, sizes, the Ca(2+) signals from endolysosomes are local and, perhaps, represent unique elementary Ca(2+) events. These localized signals can be converted into regenerative global Ca(2+) waves by triggering Ca(2+)-induced Ca(2+) release from endoplasmic reticulum. We will discuss the implications of these findings and the significance of TPCs in integrative Ca(2+) signaling in animal cells.
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