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Carey RM, Palmer JN, Adappa ND, Lee RJ. Loss of CFTR function is associated with reduced bitter taste receptor-stimulated nitric oxide innate immune responses in nasal epithelial cells and macrophages. Front Immunol 2023; 14:1096242. [PMID: 36742335 PMCID: PMC9890060 DOI: 10.3389/fimmu.2023.1096242] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2022] [Accepted: 01/03/2023] [Indexed: 01/19/2023] Open
Abstract
Introduction Bitter taste receptors (T2Rs) are G protein-coupled receptors identified on the tongue but expressed all over the body, including in airway cilia and macrophages, where T2Rs serve an immune role. T2R isoforms detect bitter metabolites (quinolones and acyl-homoserine lactones) secreted by gram negative bacteria, including Pseudomonas aeruginosa, a major pathogen in cystic fibrosis (CF). T2R activation by bitter bacterial products triggers calcium-dependent nitric oxide (NO) production. In airway cells, the NO increases mucociliary clearance and has direct antibacterial properties. In macrophages, the same pathway enhances phagocytosis. Because prior studies linked CF with reduced NO, we hypothesized that CF cells may have reduced T2R/NO responses, possibly contributing to reduced innate immunity in CF. Methods Immunofluorescence, qPCR, and live cell imaging were used to measure T2R localization, calcium and NO signaling, ciliary beating, and antimicrobial responses in air-liquid interface cultures of primary human nasal epithelial cells and immortalized bronchial cell lines. Immunofluorescence and live cell imaging was used to measure T2R signaling and phagocytosis in primary human monocyte-derived macrophages. Results Primary nasal epithelial cells from both CF and non-CF patients exhibited similar T2R expression, localization, and calcium signals. However, CF cells exhibited reduced NO production also observed in immortalized CFBE41o- CF cells and non-CF 16HBE cells CRISPR modified with CF-causing mutations in the CF transmembrane conductance regulator (CFTR). NO was restored by VX-770/VX-809 corrector/potentiator pre-treatment, suggesting reduced NO in CF cells is due to loss of CFTR function. In nasal cells, reduced NO correlated with reduced ciliary and antibacterial responses. In primary human macrophages, inhibition of CFTR reduced NO production and phagocytosis during T2R stimulation. Conclusions Together, these data suggest an intrinsic deficiency in T2R/NO signaling caused by loss of CFTR function that may contribute to intrinsic susceptibilities of CF patients to P. aeruginosa and other gram-negative bacteria that activate T2Rs.
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Affiliation(s)
- Ryan M Carey
- Department of Otorhinolaryngology-Head and Neck Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - James N Palmer
- Department of Otorhinolaryngology-Head and Neck Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Nithin D Adappa
- Department of Otorhinolaryngology-Head and Neck Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
| | - Robert J Lee
- Department of Otorhinolaryngology-Head and Neck Surgery, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States.,Department of Physiology, Perelman School of Medicine, University of Pennsylvania, Philadelphia, PA, United States
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2
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Sweet Taste Signaling: The Core Pathways and Regulatory Mechanisms. Int J Mol Sci 2022; 23:ijms23158225. [PMID: 35897802 PMCID: PMC9329783 DOI: 10.3390/ijms23158225] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2022] [Revised: 07/23/2022] [Accepted: 07/25/2022] [Indexed: 12/10/2022] Open
Abstract
Sweet taste, a proxy for sugar-derived calories, is an important driver of food intake, and animals have evolved robust molecular and cellular machinery for sweet taste signaling. The overconsumption of sugar-derived calories is a major driver of obesity and other metabolic diseases. A fine-grained appreciation of the dynamic regulation of sweet taste signaling mechanisms will be required for designing novel noncaloric sweeteners with better hedonic and metabolic profiles and improved consumer acceptance. Sweet taste receptor cells express at least two signaling pathways, one mediated by a heterodimeric G-protein coupled receptor encoded by taste 1 receptor members 2 and 3 (TAS1R2 + TAS1R3) genes and another by glucose transporters and the ATP-gated potassium (KATP) channel. Despite these important discoveries, we do not fully understand the mechanisms regulating sweet taste signaling. We will introduce the core components of the above sweet taste signaling pathways and the rationale for having multiple pathways for detecting sweet tastants. We will then highlight the roles of key regulators of the sweet taste signaling pathways, including downstream signal transduction pathway components expressed in sweet taste receptor cells and hormones and other signaling molecules such as leptin and endocannabinoids.
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3
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McMahon DB, Kuek LE, Johnson ME, Johnson PO, Horn RL, Carey RM, Adappa ND, Palmer JN, Lee RJ. The bitter end: T2R bitter receptor agonists elevate nuclear calcium and induce apoptosis in non-ciliated airway epithelial cells. Cell Calcium 2022; 101:102499. [PMID: 34839223 PMCID: PMC8752513 DOI: 10.1016/j.ceca.2021.102499] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Revised: 10/21/2021] [Accepted: 10/31/2021] [Indexed: 01/03/2023]
Abstract
Bitter taste receptors (T2Rs) localize to airway motile cilia and initiate innate immune responses in retaliation to bacterial quorum sensing molecules. Activation of cilia T2Rs leads to calcium-driven NO production that increases cilia beating and directly kills bacteria. Several diseases, including chronic rhinosinusitis, COPD, and cystic fibrosis, are characterized by loss of motile cilia and/or squamous metaplasia. To understand T2R function within the altered landscape of airway disease, we studied T2Rs in non-ciliated airway cell lines and primary cells. Several T2Rs localize to the nucleus in de-differentiated cells that typically localize to cilia in differentiated cells. As cilia and nuclear import utilize shared proteins, some T2Rs may target to the nucleus in the absence of motile cilia. T2R agonists selectively elevated nuclear and mitochondrial calcium through a G-protein-coupled receptor phospholipase C mechanism. Additionally, T2R agonists decreased nuclear cAMP, increased nitric oxide, and increased cGMP, consistent with T2R signaling. Furthermore, exposure to T2R agonists led to nuclear calcium-induced mitochondrial depolarization and caspase activation. T2R agonists induced apoptosis in primary bronchial and nasal cells differentiated at air-liquid interface but then induced to a squamous phenotype by apical submersion. Air-exposed well-differentiated cells did not die. This may be a last-resort defense against bacterial infection. However, it may also increase susceptibility of de-differentiated or remodeled epithelia to damage by bacterial metabolites. Moreover, the T2R-activated apoptosis pathway occurs in airway cancer cells. T2Rs may thus contribute to microbiome-tumor cell crosstalk in airway cancers. Targeting T2Rs may be useful for activating cancer cell apoptosis while sparing surrounding tissue.
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Affiliation(s)
- Derek B. McMahon
- Department of Otorhinolaryngology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA,Correspondence: Derek B. McMahon, PhD or Robert J. Lee, PhD, Department of Otorhinolaryngology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA USA, 215-573-9766, (D.B.M.) or (R.J.L)
| | - Li Eon Kuek
- Department of Otorhinolaryngology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Madeline E. Johnson
- Department of Otorhinolaryngology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Paige O. Johnson
- Department of Otorhinolaryngology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Rachel L.J. Horn
- Department of Otorhinolaryngology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Ryan M. Carey
- Department of Otorhinolaryngology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Nithin D. Adappa
- Department of Otorhinolaryngology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - James N. Palmer
- Department of Otorhinolaryngology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA
| | - Robert J. Lee
- Department of Otorhinolaryngology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA,Department of Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania, USA,Correspondence: Derek B. McMahon, PhD or Robert J. Lee, PhD, Department of Otorhinolaryngology, University of Pennsylvania Perelman School of Medicine, Philadelphia, PA USA, 215-573-9766, (D.B.M.) or (R.J.L)
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Asli A, Higazy-Mreih S, Avital-Shacham M, Kosloff M. Residue-level determinants of RGS R4 subfamily GAP activity and specificity towards the G i subfamily. Cell Mol Life Sci 2021; 78:6305-6318. [PMID: 34292354 PMCID: PMC11072900 DOI: 10.1007/s00018-021-03898-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Revised: 06/18/2021] [Accepted: 07/09/2021] [Indexed: 01/01/2023]
Abstract
The structural basis for the GTPase-accelerating activity of regulators of G protein signaling (RGS) proteins, as well as the mechanistic basis for their specificity in interacting with the heterotrimeric (αβγ) G proteins they inactivate, is not sufficiently understood at the family level. Here, we used biochemical assays to compare RGS domains across the RGS family and map those individual residues that favorably contribute to GTPase-accelerating activity, and those residues responsible for attenuating RGS domain interactions with Gα subunits. We show that conserved interactions of RGS residues with both the Gα switch I and II regions are crucial for RGS activity, while the reciprocal effects of "modulatory" and "disruptor" residues selectively modulate RGS activity. Our results quantify how specific interactions between RGS domains and Gα subunits are set by a balance between favorable RGS residue interactions with particular Gα switch regions, and unfavorable interactions with the Gα helical domain.
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Affiliation(s)
- Ali Asli
- The Department of Human Biology, Faculty of Natural Science, University of Haifa, 199 Aba Khoushy Ave., Mt. Carmel, 3498838, Haifa, Israel
| | - Sabreen Higazy-Mreih
- The Department of Human Biology, Faculty of Natural Science, University of Haifa, 199 Aba Khoushy Ave., Mt. Carmel, 3498838, Haifa, Israel
| | - Meirav Avital-Shacham
- The Department of Human Biology, Faculty of Natural Science, University of Haifa, 199 Aba Khoushy Ave., Mt. Carmel, 3498838, Haifa, Israel
| | - Mickey Kosloff
- The Department of Human Biology, Faculty of Natural Science, University of Haifa, 199 Aba Khoushy Ave., Mt. Carmel, 3498838, Haifa, Israel.
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Kavaliauskienė I, Domarkienė I, Ambrozaitytė L, Barauskienė L, Meškienė R, Arasimavičius J, Irnius A, Kučinskas V. Association study of taste preference: Analysis in the Lithuanian population. Food Sci Nutr 2021; 9:4310-4321. [PMID: 34401081 PMCID: PMC8358374 DOI: 10.1002/fsn3.2401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2021] [Revised: 05/05/2021] [Accepted: 05/22/2021] [Indexed: 12/20/2022] Open
Abstract
Taste has strong evolutionary basis in the sense of survival by influencing our behavior to obtain food/medicine or avoid poisoning. It is a complex trait and varies among individuals and distinct populations. We aimed to investigate the association between known genetic factors (673 SNPs) and taste preference in the Lithuanian population, as well as to determine a reasonable method for qualitative evaluation of a specific taste phenotype for further genetic analysis. Study group included individuals representing six ethnolinguistic regions of Lithuania. Case and control groups for each taste were determined according to the answers selected to the taste-specific and frequency of specific food consumption questions. Sample sizes (case/control) for each taste are as follows: sweetness (55/179), bitterness (82/208), sourness (32/259), saltiness (42/249), and umami (96/190). Genotypes were extracted from the Illumina HumanOmniExpress-12v1.1 arrays' genotyping data. Analysis was performed using PLINK v1.9. We found associations between the main known genetic factors and four taste preferences in the Lithuanian population: sweetness-genes TAS1R3, TAS1R2, and GNAT3 (three SNPs); bitterness-genes CA6 and TAS2R38 (six SNPs); sourness-genes PKD2L1, ACCN2, PKD1L3, and ACCN1 (48 SNPs); and saltiness-genes SCNN1B and TRPV1 (five SNPs). We found our questionnaire as a beneficial aid for qualitative evaluation of taste preference. This was the first initiative to analyze genetic factors related to taste preference in the Lithuanian population. Besides, this study reproduces, supports, and complements results of previous limited taste genetic studies or ones that lack comprehensive results concerning distinct (ethnic) human populations.
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Affiliation(s)
- Ingrida Kavaliauskienė
- Department of Human and Medical GeneticsInstitute of Biomedical ScienceFaculty of MedicineVilnius UniversityVilniusLithuania
| | - Ingrida Domarkienė
- Department of Human and Medical GeneticsInstitute of Biomedical ScienceFaculty of MedicineVilnius UniversityVilniusLithuania
| | - Laima Ambrozaitytė
- Department of Human and Medical GeneticsInstitute of Biomedical ScienceFaculty of MedicineVilnius UniversityVilniusLithuania
| | - Lina Barauskienė
- Department of Human and Medical GeneticsInstitute of Biomedical ScienceFaculty of MedicineVilnius UniversityVilniusLithuania
| | - Raimonda Meškienė
- Department of Human and Medical GeneticsInstitute of Biomedical ScienceFaculty of MedicineVilnius UniversityVilniusLithuania
| | - Justas Arasimavičius
- Department of Human and Medical GeneticsInstitute of Biomedical ScienceFaculty of MedicineVilnius UniversityVilniusLithuania
| | - Algimantas Irnius
- Department of Human and Medical GeneticsInstitute of Biomedical ScienceFaculty of MedicineVilnius UniversityVilniusLithuania
| | - Vaidutis Kučinskas
- Department of Human and Medical GeneticsInstitute of Biomedical ScienceFaculty of MedicineVilnius UniversityVilniusLithuania
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Kohanski MA, Brown L, Orr M, Tan LH, Adappa ND, Palmer JN, Rubenstein RC, Cohen NA. Bitter taste receptor agonists regulate epithelial two-pore potassium channels via cAMP signaling. Respir Res 2021; 22:31. [PMID: 33509163 PMCID: PMC7844973 DOI: 10.1186/s12931-021-01631-0] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2020] [Accepted: 01/20/2021] [Indexed: 11/20/2022] Open
Abstract
Background Epithelial solitary chemosensory cell (tuft cell) bitter taste signal transduction occurs through G protein coupled receptors and calcium-dependent signaling pathways. Type II taste cells, which utilize the same bitter taste signal transduction pathways, may also utilize cyclic adenosine monophosphate (cAMP) as an independent signaling messenger in addition to calcium. Methods In this work we utilized specific pharmacologic inhibitors to interrogate the short circuit current (Isc) of polarized nasal epithelial cells mounted in Ussing chambers to assess the electrophysiologic changes associated with bitter agonist (denatonium) treatment. We also assessed release of human β-defensin-2 from polarized nasal epithelial cultures following treatment with denatonium benzoate and/or potassium channel inhibitors. Results We demonstrate that the bitter taste receptor agonist, denatonium, decreases human respiratory epithelial two-pore potassium (K2P) current in polarized nasal epithelial cells mounted in Ussing chambers. Our data further suggest that this occurs via a cAMP-dependent signaling pathway. We also demonstrate that this decrease in potassium current lowers the threshold for denatonium to stimulate human β-defensin-2 release. Conclusions These data thus demonstrate that, in addition to taste transducing calcium-dependent signaling, bitter taste receptor agonists can also activate cAMP-dependent respiratory epithelial signaling pathways to modulate K2P currents. Bitter-agonist regulation of potassium currents may therefore serve as a means of rapid regional epithelial signaling, and further study of these pathways may provide new insights into regulation of mucosal ionic composition and innate mechanisms of epithelial defense.
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Affiliation(s)
- Michael A Kohanski
- Department of Otorhinolaryngology-Head and Neck Surgery, Division of Rhinology, University of Pennsylvania Medical Center, Perelman School of Medicine, 5th Floor Ravdin Building, 3400 Spruce Street, Philadelphia, PA, USA.
| | - Lauren Brown
- Cystic Fibrosis Center, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Melissa Orr
- Cystic Fibrosis Center, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Li Hui Tan
- Department of Otorhinolaryngology-Head and Neck Surgery, Division of Rhinology, University of Pennsylvania Medical Center, Perelman School of Medicine, 5th Floor Ravdin Building, 3400 Spruce Street, Philadelphia, PA, USA
| | - Nithin D Adappa
- Department of Otorhinolaryngology-Head and Neck Surgery, Division of Rhinology, University of Pennsylvania Medical Center, Perelman School of Medicine, 5th Floor Ravdin Building, 3400 Spruce Street, Philadelphia, PA, USA
| | - James N Palmer
- Department of Otorhinolaryngology-Head and Neck Surgery, Division of Rhinology, University of Pennsylvania Medical Center, Perelman School of Medicine, 5th Floor Ravdin Building, 3400 Spruce Street, Philadelphia, PA, USA
| | - Ronald C Rubenstein
- Cystic Fibrosis Center, The Children's Hospital of Philadelphia, Philadelphia, PA, USA.,Department of Pediatrics, University of Pennsylvania, Perelman School of Medicine, Philadelphia, PA, USA.,Division of Allergy and Pulmonary Medicine, Department of Pediatrics, Washington University in St. Louis School of Medicine, St. Louis, MO, USA
| | - Noam A Cohen
- Department of Otorhinolaryngology-Head and Neck Surgery, Division of Rhinology, University of Pennsylvania Medical Center, Perelman School of Medicine, 5th Floor Ravdin Building, 3400 Spruce Street, Philadelphia, PA, USA.,Corporal Michael J. Crescenz Veterans Administration Medical Center, Philadelphia, PA, USA.,Monell Chemical Senses Institute, Philadelphia, PA, USA
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7
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Schroer AB, Branyan KW, Gross JD, Chantler PD, Kimple AJ, Vandenbeuch A, Siderovski DP. The stability of tastant detection by mouse lingual chemosensory tissue requires Regulator of G protein Signaling-21 (RGS21). Chem Senses 2021; 46:6414340. [PMID: 34718440 DOI: 10.1093/chemse/bjab048] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The T1R and T2R families of G protein-coupled receptors (GPCRs) initiate tastant perception by signaling via guanine nucleotide exchange and hydrolysis performed by associated heterotrimeric G proteins (Gαβγ). Heterotrimeric G protein signal termination is sped up by Gα-directed GTPase-accelerating proteins (GAPs) known as the Regulators of G protein Signaling (RGS proteins). Of this family, RGS21 is highly expressed in lingual epithelial cells and we have shown it acting in vitro to decrease the potency of bitterants on cultured cells. However, constitutive RGS21 loss in mice reduces organismal response to GPCR-mediated tastants-opposite to expectations arising from observed in vitro activity of RGS21 as a GAP and inhibitor of T2R signaling. Here, we show reduced quinine aversion and reduced sucrose preference by mice lacking RGS21 does not result from post-ingestive effects, as taste-salient brief-access tests confirm the reduced bitterant aversion and reduced sweetener preference seen using two-bottle choice testing. Eliminating Rgs21 expression after chemosensory system development, via tamoxifen-induced Cre recombination in eight week-old mice, led to a reduction in quinine aversive behavior that advanced over time, suggesting that RGS21 functions as a negative regulator to sustain stable bitter tastant reception. Consistent with this notion, we observed downregulation of multiple T2R proteins in the lingual tissue of Rgs21-deficient mice. Reduced tastant-mediated responses exhibited by mice lacking Rgs21 expression either since birth or in adulthood has highlighted the potential requirement for a GPCR GAP to maintain the full character of tastant signaling, likely at the level of mitigating receptor downregulation.
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Affiliation(s)
- Adam B Schroer
- Department of Neuroscience, West Virginia University School of Medicine, 64 Medical Center Drive, Morgantown, WV 26506, USA
| | - Kayla W Branyan
- Division of Exercise Physiology, West Virginia University School of Medicine, 64 Medical Center Drive, Morgantown, WV 26506, USA
| | - Joshua D Gross
- Department of Cell Biology, Duke University Medical Center, 307 Research Drive, Durham, NC 27710, USA
| | - Paul D Chantler
- Division of Exercise Physiology, West Virginia University School of Medicine, 64 Medical Center Drive, Morgantown, WV 26506, USA
| | - Adam J Kimple
- Department of Otolaryngology and Marsico Lung Institute, UNC School of Medicine , 170 Manning Drive, Chapel Hill, NC 27599-7070, USA
| | - Aurelie Vandenbeuch
- Department of Otolaryngology, University of Colorado-Denver, Anschutz Medical Campus, 12700 E. 19th Avenue, Aurora, CO 80045, USA
| | - David P Siderovski
- Department of Pharmacology & Neuroscience, Graduate School of Biomedical Sciences, University of North Texas Health Science Center, 3500 Camp Bowie Blvd, Fort Worth, TX 76107, USA
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Bloxham CJ, Foster SR, Thomas WG. A Bitter Taste in Your Heart. Front Physiol 2020; 11:431. [PMID: 32457649 PMCID: PMC7225360 DOI: 10.3389/fphys.2020.00431] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2020] [Accepted: 04/08/2020] [Indexed: 12/11/2022] Open
Abstract
The human genome contains ∼29 bitter taste receptors (T2Rs), which are responsible for detecting thousands of bitter ligands, including toxic and aversive compounds. This sentinel function varies between individuals and is underpinned by naturally occurring T2R polymorphisms, which have also been associated with disease. Recent studies have reported the expression of T2Rs and their downstream signaling components within non-gustatory tissues, including the heart. Though the precise role of T2Rs in the heart remains unclear, evidence points toward a role in cardiac contractility and overall vascular tone. In this review, we summarize the extra-oral expression of T2Rs, focusing on evidence for expression in heart; we speculate on the range of potential ligands that may activate them; we define the possible signaling pathways they activate; and we argue that their discovery in heart predicts an, as yet, unappreciated cardiac physiology.
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Affiliation(s)
- Conor J Bloxham
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, St Lucia, QLD, Australia
| | - Simon R Foster
- Department of Biochemistry and Molecular Biology, Monash Biomedicine Discovery Institute, Monash University, Clayton, VIC, Australia
| | - Walter G Thomas
- School of Biomedical Sciences, Faculty of Medicine, The University of Queensland, St Lucia, QLD, Australia
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Purnell PR, Addicks BL, Zalzal HG, Shapiro S, Wen S, Ramadan HH, Setola V, Siderovski DP. Single Nucleotide Polymorphisms in Chemosensory Pathway Genes GNB3, TAS2R19, and TAS2R38 Are Associated with Chronic Rhinosinusitis. Int Arch Allergy Immunol 2019; 180:72-78. [PMID: 31137020 DOI: 10.1159/000499875] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/16/2019] [Accepted: 03/22/2019] [Indexed: 12/19/2022] Open
Abstract
BACKGROUND Chronic rhinosinusitis (CRS) is a multifaceted disease with a significant genetic component. The importance of taste receptor signaling has recently been highlighted in CRS; single nucleotide polymorphisms (SNPs) of bitter tastant-responsive G-protein-coupled receptors have been linked with CRS and with altered innate immune responses to multiple bacterially derived signals. OBJECTIVE To determine in CRS the frequency of six SNPs in genes with known bitter tastant signaling function. METHODS Genomic DNA was isolated from 74 CRS volunteers in West Virginia, and allele frequency was determined and compared with demographically matched data from the 1,000 Genomes database. RESULTS For two SNPs in a gene recently associated with bitterant signaling regulation, RGS21, there were no associations with CRS (although the frequency of the minor allele of RGS21, rs7528947, was seen to increase with increasing Lund-Mackay CT staging score). Two TAS2R bitter taste receptor gene variants (TAS2R19 rs10772420 and TAS2R38 rs713598), identified in prior CRS genetics studies, were found to have similar associations in this study. CONCLUSION Unique to our study is the establishment of an association between CRS in this patient population and GNB3 SNP rs5443, a variation in an established G protein component downstream of bitterant receptor signal transduction.
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Affiliation(s)
- Phillip R Purnell
- Department of Otolaryngology, Head and Neck Surgery, West Virginia University School of Medicine, Morgantown, West Virginia, USA
| | - Benjamin L Addicks
- Department of Otolaryngology, Head and Neck Surgery, West Virginia University School of Medicine, Morgantown, West Virginia, USA
| | - Habib G Zalzal
- Department of Otolaryngology, Head and Neck Surgery, West Virginia University School of Medicine, Morgantown, West Virginia, USA
| | - Scott Shapiro
- Department of Otolaryngology, Head and Neck Surgery, West Virginia University School of Medicine, Morgantown, West Virginia, USA
| | - Sijin Wen
- Department of Biostatistics, West Virginia University School of Public Health, Morgantown, West Virginia, USA
| | - Hassan H Ramadan
- Department of Otolaryngology, Head and Neck Surgery, West Virginia University School of Medicine, Morgantown, West Virginia, USA
| | - Vincent Setola
- Department of Physiology and Pharmacology, West Virginia University School of Medicine, Morgantown, West Virginia, USA.,Department of Neuroscience, West Virginia University School of Medicine, Morgantown, West Virginia, USA.,Department of Behavioral Medicine and Psychiatry, West Virginia University School of Medicine, Morgantown, West Virginia, USA
| | - David P Siderovski
- Department of Physiology and Pharmacology, West Virginia University School of Medicine, Morgantown, West Virginia, USA,
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Squires KE, Montañez-Miranda C, Pandya RR, Torres MP, Hepler JR. Genetic Analysis of Rare Human Variants of Regulators of G Protein Signaling Proteins and Their Role in Human Physiology and Disease. Pharmacol Rev 2018; 70:446-474. [PMID: 29871944 DOI: 10.1124/pr.117.015354] [Citation(s) in RCA: 49] [Impact Index Per Article: 8.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Regulators of G protein signaling (RGS) proteins modulate the physiologic actions of many neurotransmitters, hormones, and other signaling molecules. Human RGS proteins comprise a family of 20 canonical proteins that bind directly to G protein-coupled receptors/G protein complexes to limit the lifetime of their signaling events, which regulate all aspects of cell and organ physiology. Genetic variations account for diverse human traits and individual predispositions to disease. RGS proteins contribute to many complex polygenic human traits and pathologies such as hypertension, atherosclerosis, schizophrenia, depression, addiction, cancers, and many others. Recent analysis indicates that most human diseases are due to extremely rare genetic variants. In this study, we summarize physiologic roles for RGS proteins and links to human diseases/traits and report rare variants found within each human RGS protein exome sequence derived from global population studies. Each RGS sequence is analyzed using recently described bioinformatics and proteomic tools for measures of missense tolerance ratio paired with combined annotation-dependent depletion scores, and protein post-translational modification (PTM) alignment cluster analysis. We highlight selected variants within the well-studied RGS domain that likely disrupt RGS protein functions and provide comprehensive variant and PTM data for each RGS protein for future study. We propose that rare variants in functionally sensitive regions of RGS proteins confer profound change-of-function phenotypes that may contribute, in newly appreciated ways, to complex human diseases and/or traits. This information provides investigators with a valuable database to explore variation in RGS protein function, and for targeting RGS proteins as future therapeutic targets.
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Affiliation(s)
- Katherine E Squires
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia (K.E.S., C.M.-M., J.R.H.); and School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia (R.R.P., M.P.T.)
| | - Carolina Montañez-Miranda
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia (K.E.S., C.M.-M., J.R.H.); and School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia (R.R.P., M.P.T.)
| | - Rushika R Pandya
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia (K.E.S., C.M.-M., J.R.H.); and School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia (R.R.P., M.P.T.)
| | - Matthew P Torres
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia (K.E.S., C.M.-M., J.R.H.); and School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia (R.R.P., M.P.T.)
| | - John R Hepler
- Department of Pharmacology, Emory University School of Medicine, Atlanta, Georgia (K.E.S., C.M.-M., J.R.H.); and School of Biological Sciences, Georgia Institute of Technology, Atlanta, Georgia (R.R.P., M.P.T.)
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Perschbacher KJ, Deng G, Fisher RA, Gibson-Corley KN, Santillan MK, Grobe JL. Regulators of G protein signaling in cardiovascular function during pregnancy. Physiol Genomics 2018; 50:590-604. [PMID: 29702036 PMCID: PMC6139632 DOI: 10.1152/physiolgenomics.00037.2018] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
G protein-coupled receptor signaling mechanisms are implicated in many aspects of cardiovascular control, and dysfunction of such signaling mechanisms is commonly associated with disease states. Investigators have identified a large number of regulator of G protein signaling (RGS) proteins that variously contribute to the modulation of intracellular second-messenger signaling kinetics. These many RGS proteins each interact with a specific set of second-messenger cascades and receptor types and exhibit tissue-specific expression patterns. Increasing evidence supports the contribution of RGS proteins, or their loss, in the pathogenesis of cardiovascular dysfunctions. This review summarizes the current understanding of the functional contributions of RGS proteins, particularly within the B/R4 family, in cardiovascular disorders of pregnancy including gestational hypertension, uterine artery dysfunction, and preeclampsia.
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Affiliation(s)
| | - Guorui Deng
- Department of Pharmacology, University of Iowa , Iowa City, Iowa
| | - Rory A Fisher
- Department of Pharmacology, University of Iowa , Iowa City, Iowa
| | - Katherine N Gibson-Corley
- Department of Pathology, University of Iowa , Iowa City, Iowa
- UIHC Center for Hypertension Research, University of Iowa , Iowa City, Iowa
| | - Mark K Santillan
- Department of Obstetrics & Gynecology, University of Iowa , Iowa City, Iowa
- UIHC Center for Hypertension Research, University of Iowa , Iowa City, Iowa
- Abboud Cardiovascular Research Center, University of Iowa , Iowa City, Iowa
| | - Justin L Grobe
- Department of Pharmacology, University of Iowa , Iowa City, Iowa
- UIHC Center for Hypertension Research, University of Iowa , Iowa City, Iowa
- Abboud Cardiovascular Research Center, University of Iowa , Iowa City, Iowa
- Fraternal Order of Eagles' Diabetes Research Center, University of Iowa , Iowa City, Iowa
- Obesity Education & Research Initiative, University of Iowa , Iowa City, Iowa
- Iowa Neuroscience Institute, University of Iowa , Iowa City, Iowa
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12
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Schroer AB, Gross JD, Kaski SW, Wix K, Siderovski DP, Vandenbeuch A, Setola V. Development of Full Sweet, Umami, and Bitter Taste Responsiveness Requires Regulator of G protein Signaling-21 (RGS21). Chem Senses 2018; 43:367-378. [PMID: 29701767 PMCID: PMC6276893 DOI: 10.1093/chemse/bjy024] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023] Open
Abstract
The mammalian tastes of sweet, umami, and bitter are initiated by activation of G protein-coupled receptors (GPCRs) of the T1R and T2R families on taste receptor cells. GPCRs signal via nucleotide exchange and hydrolysis, the latter hastened by GTPase-accelerating proteins (GAPs) that include the Regulators of G protein Signaling (RGS) protein family. We previously reported that RGS21, uniquely expressed in Type II taste receptor cells, decreases the potency of bitter-stimulated T2R signaling in cultured cells, consistent with its in vitro GAP activity. However, the role of RGS21 in organismal responses to GPCR-mediated tastants was not established. Here, we characterized mice lacking the Rgs21 fifth exon. Eliminating Rgs21 expression had no effect on body mass accumulation (a measure of alimentation), fungiform papillae number and morphology, circumvallate papillae morphology, and taste bud number. Two-bottle preference tests, however, revealed that Rgs21-null mice have blunted aversion to quinine and denatonium, and blunted preference for monosodium glutamate, the sweeteners sucrose and SC45647, and (surprisingly) NaCl. Observed reductions in GPCR-mediated tastant responses upon Rgs21 loss are opposite to original expectations, given that loss of RGS21-a GPCR signaling negative regulator-should lead to increased responsiveness to tastant-mediated GPCR signaling (all else being equal). Yet, reduced organismal tastant responses are consistent with observations of reduced chorda tympani nerve recordings in Rgs21-null mice. Reduced tastant-mediated responses and behaviors exhibited by adult mice lacking Rgs21 expression since birth have thus revealed an underappreciated requirement for a GPCR GAP to establish the full character of tastant signaling.
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Affiliation(s)
- Adam B Schroer
- Department of Physiology, Pharmacology, and Neuroscience, West Virginia School of Medicine, One Medical Center Drive, Morgantown, WV, USA
| | - Joshua D Gross
- Department of Physiology, Pharmacology, and Neuroscience, West Virginia School of Medicine, One Medical Center Drive, Morgantown, WV, USA
| | - Shane W Kaski
- Department of Physiology, Pharmacology, and Neuroscience, West Virginia School of Medicine, One Medical Center Drive, Morgantown, WV, USA
| | - Kim Wix
- Department of Physiology, Pharmacology, and Neuroscience, West Virginia School of Medicine, One Medical Center Drive, Morgantown, WV, USA
| | - David P Siderovski
- Department of Physiology, Pharmacology, and Neuroscience, West Virginia School of Medicine, One Medical Center Drive, Morgantown, WV, USA
| | - Aurelie Vandenbeuch
- Department of Otolaryngology, University of Colorado - Denver, Anschutz Medical Campus, Aurora, CO, USA
| | - Vincent Setola
- Department of Physiology, Pharmacology, and Neuroscience, West Virginia School of Medicine, One Medical Center Drive, Morgantown, WV, USA
- Department of Behavioral Medicine and Psychiatry, West Virginia School of Medicine, Morgantown, WV, USA
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13
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Freund JR, Mansfield CJ, Doghramji LJ, Adappa ND, Palmer JN, Kennedy DW, Reed DR, Jiang P, Lee RJ. Activation of airway epithelial bitter taste receptors by Pseudomonas aeruginosa quinolones modulates calcium, cyclic-AMP, and nitric oxide signaling. J Biol Chem 2018; 293:9824-9840. [PMID: 29748385 DOI: 10.1074/jbc.ra117.001005] [Citation(s) in RCA: 72] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2017] [Revised: 04/17/2018] [Indexed: 12/12/2022] Open
Abstract
Bitter taste receptors (taste family 2 bitter receptor proteins; T2Rs), discovered in many tissues outside the tongue, have recently become potential therapeutic targets. We have shown previously that airway epithelial cells express several T2Rs that activate innate immune responses that may be important for treatment of airway diseases such as chronic rhinosinusitis. It is imperative to more clearly understand what compounds activate airway T2Rs as well as their full range of functions. T2R isoforms in airway motile cilia (T2R4, -14, -16, and -38) produce bactericidal levels of nitric oxide (NO) that also increase ciliary beating, promoting clearance of mucus and trapped pathogens. Bacterial quorum-sensing acyl-homoserine lactones activate T2Rs and stimulate these responses in primary airway cells. Quinolones are another type of quorum-sensing molecule used by Pseudomonas aeruginosa To elucidate whether bacterial quinolones activate airway T2Rs, we analyzed calcium, cAMP, and NO dynamics using a combination of fluorescent indicator dyes and FRET-based protein biosensors. T2R-transfected HEK293T cells, several lung epithelial cell lines, and primary sinonasal cells grown and differentiated at the air-liquid interface were tested with 2-heptyl-3-hydroxy-4-quinolone (known as Pseudomonas quinolone signal; PQS), 2,4-dihydroxyquinolone, and 4-hydroxy-2-heptylquinolone (HHQ). In HEK293T cells, PQS activated T2R4, -16, and -38, whereas HHQ activated T2R14. 2,4-Dihydroxyquinolone had no effect. PQS and HHQ increased calcium and decreased both baseline and stimulated cAMP levels in cultured and primary airway cells. In primary cells, PQS and HHQ activated levels of NO synthesis previously shown to be bactericidal. This study suggests that airway T2R-mediated immune responses are activated by bacterial quinolones as well as acyl-homoserine lactones.
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Affiliation(s)
- Jenna R Freund
- From the Departments of Otorhinolaryngology-Head and Neck Surgery and
| | | | | | - Nithin D Adappa
- From the Departments of Otorhinolaryngology-Head and Neck Surgery and
| | - James N Palmer
- From the Departments of Otorhinolaryngology-Head and Neck Surgery and
| | - David W Kennedy
- From the Departments of Otorhinolaryngology-Head and Neck Surgery and
| | - Danielle R Reed
- the Monell Chemical Senses Center, Philadelphia, Pennsylvania 19104
| | - Peihua Jiang
- the Monell Chemical Senses Center, Philadelphia, Pennsylvania 19104
| | - Robert J Lee
- From the Departments of Otorhinolaryngology-Head and Neck Surgery and .,Physiology, University of Pennsylvania Perelman School of Medicine, Philadelphia, Pennsylvania 19104 and
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Wolf A, Renner B, Tomazic PV, Mueller CA. Gustatory Function in Patients With Chronic Rhinosinusitis. Ann Otol Rhinol Laryngol 2018; 127:229-234. [DOI: 10.1177/0003489418754583] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Affiliation(s)
- Axel Wolf
- Medical University of Graz, Department of Otothinolaryngology, Head and Neck Surgery, Graz, Austria
| | - Bertold Renner
- University of Erlangen-Nuernberg, Institute of Experimental and Clinical Pharmacology and Toxicology, Erlangen, Germany
| | - Peter V. Tomazic
- Medical University of Graz, Department of Otothinolaryngology, Head and Neck Surgery, Graz, Austria
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Riedel K, Sombroek D, Fiedler B, Siems K, Krohn M. Human cell-based taste perception - a bittersweet job for industry. Nat Prod Rep 2017; 34:484-495. [PMID: 28393162 DOI: 10.1039/c6np00123h] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Abstract
Covering: 2000 to 2016On the molecular level humans sense food by a variety of specialized tissues which express sensory receptors to handle nutritive value. In general, this means the interplay of gustatory, olfactory, trigeminal and haptic sensation is translated into perception and leads, in terms of taste, to descriptions like sweet, bitter, salty, sour and umami. Further perceptions include astringent, cool, hot, prickle, lingering, kokumi and fatty to name predominant characterizations. It is still not fully understood how this plethora of impressions can be perceived by quite a limited number of receptors obviously being the initial compilers to judge palatability. However, since the discovery of mammalian taste receptors (TASRs) almost 30 years ago the use of taste receptors in cell-based screening campaigns is advancing in industrial approaches. The article will highlight the impacts and the limits of cell-based guided identification of taste modulators for food applications with an emphasis on sweet, bitter and savory taste as well as implications emerging from natural products.
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Affiliation(s)
- K Riedel
- BRAIN AG, Darmstädter Str. 34-36, 64673 Zwingenberg, Germany.
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Abstract
The present review examines the pig as a model for physiological studies in human subjects related to nutrient sensing, appetite regulation, gut barrier function, intestinal microbiota and nutritional neuroscience. The nutrient-sensing mechanisms regarding acids (sour), carbohydrates (sweet), glutamic acid (umami) and fatty acids are conserved between humans and pigs. In contrast, pigs show limited perception of high-intensity sweeteners and NaCl and sense a wider array of amino acids than humans. Differences on bitter taste may reflect the adaptation to ecosystems. In relation to appetite regulation, plasma concentrations of cholecystokinin and glucagon-like peptide-1 are similar in pigs and humans, while peptide YY in pigs is ten to twenty times higher and ghrelin two to five times lower than in humans. Pigs are an excellent model for human studies for vagal nerve function related to the hormonal regulation of food intake. Similarly, the study of gut barrier functions reveals conserved defence mechanisms between the two species particularly in functional permeability. However, human data are scant for some of the defence systems and nutritional programming. The pig model has been valuable for studying the changes in human microbiota following nutritional interventions. In particular, the use of human flora-associated pigs is a useful model for infants, but the long-term stability of the implanted human microbiota in pigs remains to be investigated. The similarity of the pig and human brain anatomy and development is paradigmatic. Brain explorations and therapies described in pig, when compared with available human data, highlight their value in nutritional neuroscience, particularly regarding functional neuroimaging techniques.
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17
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Rowell TR, Tarran R. Will chronic e-cigarette use cause lung disease? Am J Physiol Lung Cell Mol Physiol 2015; 309:L1398-409. [PMID: 26408554 PMCID: PMC4683316 DOI: 10.1152/ajplung.00272.2015] [Citation(s) in RCA: 81] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2015] [Accepted: 09/22/2015] [Indexed: 12/22/2022] Open
Abstract
Chronic tobacco smoking is a major cause of preventable morbidity and mortality worldwide. In the lung, tobacco smoking increases the risk of lung cancer, and also causes chronic obstructive pulmonary disease (COPD), which encompasses both emphysema and chronic bronchitis. E-cigarettes (E-Cigs), or electronic nicotine delivery systems, were developed over a decade ago and are designed to deliver nicotine without combusting tobacco. Although tobacco smoking has declined since the 1950s, E-Cig usage has increased, attracting both former tobacco smokers and never smokers. E-Cig liquids (e-liquids) contain nicotine in a glycerol/propylene glycol vehicle with flavorings, which are vaporized and inhaled. To date, neither E-Cig devices, nor e-liquids, are regulated by the Food and Drug Administration (FDA). The FDA has proposed a deeming rule, which aims to initiate legislation to regulate E-Cigs, but the timeline to take effect is uncertain. Proponents of E-Cigs say that they are safe and should not be regulated. Opposition is varied, with some opponents proposing that E-Cig usage will introduce a new generation to nicotine addiction, reversing the decline seen with tobacco smoking, or that E-Cigs generally may not be safe and will trigger diseases like tobacco. In this review, we shall discuss what is known about the effects of E-Cigs on the mammalian lung and isolated lung cells in vitro. We hope that collating this data will help illustrate gaps in the knowledge of this burgeoning field, directing researchers toward answering whether or not E-Cigs are capable of causing disease.
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Affiliation(s)
- Temperance R Rowell
- Marsico Lung Institute and Department of Cell Biology & Physiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Robert Tarran
- Marsico Lung Institute and Department of Cell Biology & Physiology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
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18
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Devillier P, Naline E, Grassin-Delyle S. The pharmacology of bitter taste receptors and their role in human airways. Pharmacol Ther 2015; 155:11-21. [PMID: 26272040 DOI: 10.1016/j.pharmthera.2015.08.001] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
The receptors involved in bitter taste perception (bitter taste receptors--T2Rs) constitute a family of G-protein-coupled receptors, of which around 29 subtypes have been identified in humans. T2R expression was initially thought to be confined to the oral cavity but has recently been described in a range of other tissues (such as the heart, gut, nasal cavity and lungs) and cell types (chemosensory, smooth muscle, endothelial, epithelial and inflammatory cells). Although it is still not clear whether endogenous T2R agonists exist, the T2R receptors recognize many natural and synthetic compounds, such as the acyl-homoserine lactones produced by bacteria, caffeine, chloroquine, and erythromycin. In the upper airways, T2Rs are involved in neurogenic inflammation and bacterial clearance. Their known effects in the lungs are exerted at three different levels. Firstly, T2R agonists increase the beating frequency of cilia on epithelial cells. Secondly, the T2Rs induce bronchial smooth muscle cells to relax. Thirdly, the T2R receptors expressed on immune cells (such as macrophages and mast cells) modulate production of pro-inflammatory mediators. Furthermore, T2R agonists are effective in inhibiting lung inflammation or smooth muscle contraction in ex vivo and asthma animal models, and are known to be involved in bacterial killing in the nasal cavity and enhancing lung function in humans. This review focuses on the pharmacology and physiological functions of T2R receptors in the upper and lower airways. It presents recently acquired knowledge suggesting that T2Rs may become valuable drug targets in the treatment of diseases such as asthma and chronic rhinosinusitis.
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Affiliation(s)
- Philippe Devillier
- Laboratoire de Pharmacologie, UPRES EA220, Hôpital Foch, 11 rue Guillaume Lenoir, 92150 Suresnes, France; Université Versailles Saint Quentin en Yvelines, UFR Sciences de la Santé, 2 avenue de la source de la Bièvre, 78180 Montigny-le-Bretonneux, France
| | - Emmanuel Naline
- Laboratoire de Pharmacologie, UPRES EA220, Hôpital Foch, 11 rue Guillaume Lenoir, 92150 Suresnes, France; Université Versailles Saint Quentin en Yvelines, UFR Sciences de la Santé, 2 avenue de la source de la Bièvre, 78180 Montigny-le-Bretonneux, France
| | - Stanislas Grassin-Delyle
- Laboratoire de Pharmacologie, UPRES EA220, Hôpital Foch, 11 rue Guillaume Lenoir, 92150 Suresnes, France; Université Versailles Saint Quentin en Yvelines, UFR Sciences de la Santé, 2 avenue de la source de la Bièvre, 78180 Montigny-le-Bretonneux, France.
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19
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Doupnik CA. RGS Redundancy and Implications in GPCR-GIRK Signaling. INTERNATIONAL REVIEW OF NEUROBIOLOGY 2015; 123:87-116. [PMID: 26422983 DOI: 10.1016/bs.irn.2015.05.010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/03/2022]
Abstract
Regulators of G protein signaling (RGS proteins) are key components of GPCR complexes, interacting directly with G protein α-subunits to enhance their intrinsic GTPase activity. The functional consequence is an accelerated termination of G protein effectors including certain ion channels. RGS proteins have a profound impact on the membrane-delimited gating behavior of G-protein-activated inwardly rectifying K(+) (GIRK) channels as demonstrated in reconstitution assays and recent RGS knockout mice studies. Akin to GPCRs and G protein αβγ subunits, multiple RGS isoforms are expressed within single GIRK-expressing neurons, suggesting functional redundancy and/or specificity in GPCR-GIRK channel signaling. The extent and impact of RGS redundancy in neuronal GPCR-GIRK channel signaling is currently not fully appreciated; however, recent studies from RGS knockout mice are providing important new clues on the impact of individual endogenous RGS proteins and the extent of RGS functional redundancy. Incorporating "tools" such as engineered RGS-resistant Gαi/o subunits provide an important assessment method for determining the impact of all endogenous RGS proteins on a given GPCR response and an accounting benchmark to assess the impact of individual RGS knockouts on overall RGS redundancy within a given neuron. Elucidating the degree of regulation attributable to specific RGS proteins in GIRK channel function will aid in the assessment of individual RGS proteins as viable therapeutic targets in epilepsy, ataxia's, memory disorders, and a growing list of neurological disorders.
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Affiliation(s)
- Craig A Doupnik
- Department of Molecular Pharmacology & Physiology, University of South Florida College of Medicine, Tampa, Florida, USA.
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Woodard GE, Jardín I, Berna-Erro A, Salido GM, Rosado JA. Regulators of G-protein-signaling proteins: negative modulators of G-protein-coupled receptor signaling. INTERNATIONAL REVIEW OF CELL AND MOLECULAR BIOLOGY 2015; 317:97-183. [PMID: 26008785 DOI: 10.1016/bs.ircmb.2015.02.001] [Citation(s) in RCA: 24] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Regulators of G-protein-signaling (RGS) proteins are a category of intracellular proteins that have an inhibitory effect on the intracellular signaling produced by G-protein-coupled receptors (GPCRs). RGS along with RGS-like proteins switch on through direct contact G-alpha subunits providing a variety of intracellular functions through intracellular signaling. RGS proteins have a common RGS domain that binds to G alpha. RGS proteins accelerate GTPase and thus enhance guanosine triphosphate hydrolysis through the alpha subunit of heterotrimeric G proteins. As a result, they inactivate the G protein and quickly turn off GPCR signaling thus terminating the resulting downstream signals. Activity and subcellular localization of RGS proteins can be changed through covalent molecular changes to the enzyme, differential gene splicing, and processing of the protein. Other roles of RGS proteins have shown them to not be solely committed to being inhibitors but behave more as modulators and integrators of signaling. RGS proteins modulate the duration and kinetics of slow calcium oscillations and rapid phototransduction and ion signaling events. In other cases, RGS proteins integrate G proteins with signaling pathways linked to such diverse cellular responses as cell growth and differentiation, cell motility, and intracellular trafficking. Human and animal studies have revealed that RGS proteins play a vital role in physiology and can be ideal targets for diseases such as those related to addiction where receptor signaling seems continuously switched on.
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Affiliation(s)
- Geoffrey E Woodard
- Department of Surgery, Uniformed Services University of the Health Sciences, Bethesda, MD, USA; Laboratory of Immunoregulation, National Institute of Allergy and Infectious Diseases, Bethesda, MD, USA
| | - Isaac Jardín
- Department of Physiology, University of Extremadura, Caceres, Spain
| | - A Berna-Erro
- Department of Physiology, University of Extremadura, Caceres, Spain
| | - Gines M Salido
- Department of Physiology, University of Extremadura, Caceres, Spain
| | - Juan A Rosado
- Department of Physiology, University of Extremadura, Caceres, Spain
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Lee RJ, Cohen NA. Taste receptors in innate immunity. Cell Mol Life Sci 2015; 72:217-36. [PMID: 25323130 PMCID: PMC4286424 DOI: 10.1007/s00018-014-1736-7] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2014] [Revised: 09/11/2014] [Accepted: 09/16/2014] [Indexed: 02/07/2023]
Abstract
Taste receptors were first identified on the tongue, where they initiate a signaling pathway that communicates information to the brain about the nutrient content or potential toxicity of ingested foods. However, recent research has shown that taste receptors are also expressed in a myriad of other tissues, from the airway and gastrointestinal epithelia to the pancreas and brain. The functions of many of these extraoral taste receptors remain unknown, but emerging evidence suggests that bitter and sweet taste receptors in the airway are important sentinels of innate immunity. This review discusses taste receptor signaling, focusing on the G-protein-coupled receptors that detect bitter, sweet, and savory tastes, followed by an overview of extraoral taste receptors and in-depth discussion of studies demonstrating the roles of taste receptors in airway innate immunity. Future research on extraoral taste receptors has significant potential for identification of novel immune mechanisms and insights into host-pathogen interactions.
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Affiliation(s)
- Robert J. Lee
- Department of Otorhinolaryngology, Perelman School of Medicine, University of Pennsylvania, Ravdin Building, 5th floor, Philadelphia, PA 19104 USA
| | - Noam A. Cohen
- Department of Otorhinolaryngology, Perelman School of Medicine, University of Pennsylvania, Ravdin Building, 5th floor, Philadelphia, PA 19104 USA
- Philadelphia Veterans Affairs Medical Center Surgical Services, 3900 Woodland Ave, Philadelphia, PA 19104 USA
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22
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Tan X, Sanderson MJ. Bitter tasting compounds dilate airways by inhibiting airway smooth muscle calcium oscillations and calcium sensitivity. Br J Pharmacol 2014; 171:646-62. [PMID: 24117140 DOI: 10.1111/bph.12460] [Citation(s) in RCA: 65] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2013] [Revised: 09/09/2013] [Accepted: 09/21/2013] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND AND PURPOSE While selective, bitter tasting, TAS2R agonists can relax agonist-contracted airway smooth muscle (ASM), their mechanism of action is unclear. However, ASM contraction is regulated by Ca²⁺ signalling and Ca²⁺ sensitivity. We have therefore investigated how the TAS2R10 agonists chloroquine, quinine and denotonium regulate contractile agonist-induced Ca²⁺ signalling and sensitivity. EXPERIMENTAL APPROACH Airways in mouse lung slices were contracted with either methacholine (MCh) or 5HT and bronchodilation assessed using phase-contrast microscopy. Ca²⁺ signalling was measured with 2-photon fluorescence microscopy of ASM cells loaded with Oregon Green, a Ca²⁺-sensitive indicator (with or without caged-IP₃). Effects on Ca²⁺ sensitivity were assessed on lung slices treated with caffeine and ryanodine to permeabilize ASM cells to Ca²⁺ . KEY RESULTS The TAS2R10 agonists dilated airways constricted by either MCh or 5HT, accompanied by inhibition of agonist-induced Ca²⁺ oscillations. However, in non-contracted airways, TAS2R10 agonists, at concentrations that maximally dilated constricted airways, did not evoke Ca²⁺ signals in ASM cells. Ca²⁺ increases mediated by the photolysis of caged-IP₃ were also attenuated by chloroquine, quinine and denotonium. In Ca²⁺-permeabilized ASM cells, the TAS2R10 agonists dilated MCh- and 5HT-constricted airways. CONCLUSIONS AND IMPLICATIONS TAS2R10 agonists reversed bronchoconstriction by inhibiting agonist-induced Ca²⁺ oscillations while simultaneously reducing the Ca²⁺ sensitivity of ASM cells. Reduction of Ca²⁺ oscillations may be due to inhibition of Ca²⁺ release through IP₃ receptors. Further characterization of bronchodilatory TAS2R agonists may lead to the development of novel therapies for the treatment of bronchoconstrictive conditions.
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Affiliation(s)
- Xiahui Tan
- Department of Microbiology and Physiological Systems, University of Massachusetts Medical School, Worcester, MA, USA
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Taste Receptor Gene Expression Outside the Gustatory System. TOPICS IN MEDICINAL CHEMISTRY 2014. [DOI: 10.1007/7355_2014_79] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
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Extrasensory perception: odorant and taste receptors beyond the nose and mouth. Pharmacol Ther 2013; 142:41-61. [PMID: 24280065 DOI: 10.1016/j.pharmthera.2013.11.004] [Citation(s) in RCA: 80] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2013] [Accepted: 11/04/2013] [Indexed: 12/22/2022]
Abstract
G protein-coupled receptors (GPCRs) represent the largest family of transmembrane receptors and are prime therapeutic targets. The odorant and taste receptors account for over half of the GPCR repertoire, yet they are generally excluded from large-scale, drug candidate analyses. Accumulating molecular evidence indicates that the odorant and taste receptors are widely expressed throughout the body and functional beyond the oronasal cavity - with roles including nutrient sensing, autophagy, muscle regeneration, regulation of gut motility, protective airway reflexes, bronchodilation, and respiratory disease. Given this expanding array of actions, the restricted perception of these GPCRs as mere mediators of smell and taste is outdated. Moreover, delineation of the precise actions of odorant and taste GPCRs continues to be hampered by the relative paucity of selective and specific experimental tools, as well as the lack of defined receptor pharmacology. In this review, we summarize the evidence for expression and function of odorant and taste receptors in tissues beyond the nose and mouth, and we highlight their broad potential in physiology and pathophysiology.
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25
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Kimple AJ, Garland AL, Cohen SP, Setola V, Willard FS, Zielinski T, Lowery RG, Tarran R, Siderovski DP. RGS21, a regulator of taste and mucociliary clearance? Laryngoscope 2013; 124:E56-63. [PMID: 23908053 DOI: 10.1002/lary.24326] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Revised: 07/27/2013] [Accepted: 07/05/2013] [Indexed: 01/08/2023]
Abstract
OBJECTIVES/HYPOTHESIS Motile cilia of airway epithelial cells help to expel harmful inhaled material. Activation of bitterant-responsive G protein-coupled receptors (GPCRs) is believed to potentiate cilia beat frequency and mucociliary clearance. In this study, we investigated whether regulator of G protein signaling-21 (RGS21) has the potential to modulate signaling pathways connected to airway mucociliary clearance, given that RGS proteins modulate GPCR signaling by acting as GTPase-accelerating proteins (GAPs) for the Gα subunits of heterotrimeric G proteins. STUDY DESIGN This is a pilot investigation to determine if RGS21, a potential tastant specific RGS gene, is expressed in sinonasal mucosa, and to determine its specific Gα substrate using in vitro biochemical assays with purified proteins. METHODS Rgs21 expression in sinonasal mucosa was determined using quantitative, real-time PCR and a transgenic mouse expressing RFP from the Rgs21 promoter. Rgs21 was cloned, over-expressed, and purified using multistep protein chromatography. Biochemical and biophysical assays were used to determine if RGS21 could bind and accelerate the hydrolysis of GTP on heterotrimeric Gα subunits. RESULTS Rgs21 was expressed in sinonasal mucosa and lingual epithelium. Purified recombinant protein directly bound and accelerated GTP hydrolysis on Gα subunits. CONCLUSIONS Rgs21 is expressed in sinonasal mucosa, is amenable to purification as a recombinant protein, and can bind to Gα(i/o/q) subunits. Furthermore, RGS21 can accelerate the hydrolysis rate of GTP on Gαi subunits. This provides evidence that RGS21 may be a negative regulator of bitterant responses. Future studies will be needed to determine the physiological role of this protein in mucociliary clearance.
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Affiliation(s)
- Adam J Kimple
- Department of Otolaryngology-Head and Neck Surgery, University of North Carolina at Chapel Hill, North Carolina, U.S.A; Department of Pharmacology, University of North Carolina at Chapel Hill, North Carolina, U.S.A
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