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Perez-Zoghbi JF, Sajorda DR, Webb DA, Arnold LA, Emala CW, Yocum GT. Imidazobenzodiazepine PI320 Relaxes Mouse Peripheral Airways by Inhibiting Calcium Mobilization. Am J Respir Cell Mol Biol 2022; 67:482-490. [PMID: 35776523 PMCID: PMC9564932 DOI: 10.1165/rcmb.2022-0084oc] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 07/01/2022] [Indexed: 02/06/2023] Open
Abstract
Asthma is a common respiratory disease characterized, in part, by excessive airway smooth muscle (ASM) contraction (airway hyperresponsiveness). Various GABAAR (γ-aminobutyric acid type A receptor) activators, including benzodiazepines, relax ASM. The GABAAR is a ligand-operated Cl- channel best known for its role in inhibitory neurotransmission in the central nervous system. Although ASM cells express GABAARs, affording a seemingly logical site of action, the mechanism(s) by which GABAAR ligands relax ASM remains unclear. PI320, a novel imidazobenzodiazepine designed for tissue selectivity, is a promising asthma drug candidate. Here, we show that PI320 alleviates methacholine (MCh)-induced bronchoconstriction in vivo and relaxes peripheral airways preconstricted with MCh ex vivo using the forced oscillation technique and precision-cut lung slice experiments, respectively. Surprisingly, the peripheral airway relaxation demonstrated in precision-cut lung slices does not appear to be GABAAR-dependent, as it is not inhibited by the GABAAR antagonist picrotoxin or the benzodiazepine antagonist flumazenil. Furthermore, we demonstrate here that PI320 inhibits MCh-induced airway constriction in the absence of external Ca2, suggesting that PI320-mediated relaxation is not mediated by inhibition of Ca2+ influx in ASM. However, PI320 does inhibit MCh-induced intracellular Ca2+ oscillations in peripheral ASM, a key mediator of contraction that is dependent on sarcoplasmic reticulum Ca2+ mobilization. Furthermore, PI320 inhibits peripheral airway constriction induced by experimentally increasing the intracellular concentration of inositol triphosphate (IP3). These novel data suggest that PI320 relaxes murine peripheral airways by inhibiting intracellular Ca2+ mobilization in ASM, likely by inhibiting Ca2+ release through IP3Rs (IP3 receptors).
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Affiliation(s)
- Jose F. Perez-Zoghbi
- Department of Anesthesiology, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York; and
| | - Dannah Rae Sajorda
- Department of Anesthesiology, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York; and
| | - Daniel A. Webb
- Department of Chemistry and Biochemistry and
- Milwaukee Institute for Drug Discovery, University of Wisconsin–Milwaukee, Milwaukee, Wisconsin
| | - Leggy A. Arnold
- Department of Chemistry and Biochemistry and
- Milwaukee Institute for Drug Discovery, University of Wisconsin–Milwaukee, Milwaukee, Wisconsin
| | - Charles W. Emala
- Department of Anesthesiology, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York; and
| | - Gene T. Yocum
- Department of Anesthesiology, Vagelos College of Physicians and Surgeons, Columbia University, New York, New York; and
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Wei B, Zhu Y, Yang P, Han Y, Wang S, Wang X, Xia S, Song X, Zhang Z, Wang S, Rondard P, Pin JP, Jiang X, Liu J. GABA B1e promotes the malignancy of human cancer cells by targeting the tyrosine phosphatase PTPN12. iScience 2021; 24:103311. [PMID: 34778730 PMCID: PMC8577127 DOI: 10.1016/j.isci.2021.103311] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/11/2021] [Revised: 09/24/2021] [Accepted: 10/14/2021] [Indexed: 01/30/2023] Open
Abstract
Neurotransmitter receptors are involved in cancer progression. Among them, the heterodimeric GABAB receptor, activated by the main inhibitory neurotransmitter GABA, is composed of the transmembrane GABAB1 and GABAB2 subunits. The oncogenic role of the isoform GABAB1e (GB1e) containing only the extracellular domain of GABAB1 remains unclear. We revealed that GB1e is largely expressed in human breast cancer (BrCa) cell lines as well as in BrCa tissues where it is upregulated. Moreover, GB1e promoted the malignancy of BrCa cells both in vitro and in vivo. We propose that GB1e favors EGFR signaling by interacting with PTPN12 to disrupt the interaction between EGFR and PTPN12, and phosphorylation of Y230 and Y404 on GB1e is required in this process. Our data highlight that the GABBR1 gene through the expression of the GB1e isoform might play an important oncogenic role in BrCa and that GB1e is of interest for the treatment of some cancers. GABAB1e promotes the malignancy of breast cancer cells both in vitro and in vivo Specific phosphorylation of GABAB1e is critical for its association with PTPN12 GABAB1e disrupts EGFR interacting with PTPN12 and induces EGFR-PI3K/Akt signaling
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Affiliation(s)
- Bo Wei
- Key Laboratory of Molecular Biophysics of MOE, International Research Center for Sensory Biology and Technology of MOST, College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan 430074, China
| | - Yini Zhu
- Key Laboratory of Molecular Biophysics of MOE, International Research Center for Sensory Biology and Technology of MOST, College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan 430074, China
| | - Peng Yang
- Department of Breast & Endocrine Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology (HUST), Wuhan 430022, China
| | - Yong Han
- Department of Pharmacy, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology (HUST), Wuhan 430022, China
| | - Suyun Wang
- Key Laboratory of Molecular Biophysics of MOE, International Research Center for Sensory Biology and Technology of MOST, College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan 430074, China
| | - Xiaomei Wang
- Key Laboratory of Molecular Biophysics of MOE, International Research Center for Sensory Biology and Technology of MOST, College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan 430074, China
| | - Shuai Xia
- Key Laboratory of Molecular Biophysics of MOE, International Research Center for Sensory Biology and Technology of MOST, College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan 430074, China
| | - Xiaoguang Song
- Key Laboratory of Molecular Biophysics of MOE, International Research Center for Sensory Biology and Technology of MOST, College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan 430074, China
| | - Zhongling Zhang
- Key Laboratory of Molecular Biophysics of MOE, International Research Center for Sensory Biology and Technology of MOST, College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan 430074, China
| | - Sheng Wang
- Key Laboratory of Molecular Biophysics of MOE, College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan 430074, China
| | - Philippe Rondard
- Institut de Génomique Fonctionnelle (IGF), Université de Montpellier, CNRS, INSERM, 34094 Montpellier, France
| | - Jean-Philippe Pin
- Institut de Génomique Fonctionnelle (IGF), Université de Montpellier, CNRS, INSERM, 34094 Montpellier, France
| | - Xinnong Jiang
- Key Laboratory of Molecular Biophysics of MOE, International Research Center for Sensory Biology and Technology of MOST, College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan 430074, China
- Corresponding author
| | - Jianfeng Liu
- Key Laboratory of Molecular Biophysics of MOE, International Research Center for Sensory Biology and Technology of MOST, College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan 430074, China
- Corresponding author
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Pavón-Romero GF, Serrano-Pérez NH, García-Sánchez L, Ramírez-Jiménez F, Terán LM. Neuroimmune Pathophysiology in Asthma. Front Cell Dev Biol 2021; 9:663535. [PMID: 34055794 PMCID: PMC8155297 DOI: 10.3389/fcell.2021.663535] [Citation(s) in RCA: 29] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2021] [Accepted: 04/15/2021] [Indexed: 12/26/2022] Open
Abstract
Asthma is a chronic inflammation of lower airway disease, characterized by bronchial hyperresponsiveness. Type I hypersensitivity underlies all atopic diseases including allergic asthma. However, the role of neurotransmitters (NT) and neuropeptides (NP) in this disease has been less explored in comparison with inflammatory mechanisms. Indeed, the airway epithelium contains pulmonary neuroendocrine cells filled with neurotransmitters (serotonin and GABA) and neuropeptides (substance P[SP], neurokinin A [NKA], vasoactive intestinal peptide [VIP], Calcitonin-gene related peptide [CGRP], and orphanins-[N/OFQ]), which are released after allergen exposure. Likewise, the autonomic airway fibers produce acetylcholine (ACh) and the neuropeptide Y(NPY). These NT/NP differ in their effects; SP, NKA, and serotonin exert pro-inflammatory effects, whereas VIP, N/OFQ, and GABA show anti-inflammatory activity. However, CGPR and ACh have dual effects. For example, the ACh-M3 axis induces goblet cell metaplasia, extracellular matrix deposition, and bronchoconstriction; the CGRP-RAMP1 axis enhances Th2 and Th9 responses; and the SP-NK1R axis promotes the synthesis of chemokines in eosinophils, mast cells, and neutrophils. In contrast, the ACh-α7nAChR axis in ILC2 diminishes the synthesis of TNF-α, IL-1, and IL-6, attenuating lung inflammation whereas, VIP-VPAC1, N/OFQ-NOP axes cause bronchodilation and anti-inflammatory effects. Some NT/NP as 5-HT and NKA could be used as biomarkers to monitor asthma patients. In fact, the asthma treatment based on inhaled corticosteroids and anticholinergics blocks M3 and TRPV1 receptors. Moreover, the administration of experimental agents such as NK1R/NK2R antagonists and exogenous VIP decrease inflammatory mediators, suggesting that regulating the effects of NT/NP represents a potential novel approach for the treatment of asthma.
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Affiliation(s)
| | | | | | | | - Luis M. Terán
- Department of Immunogenetics and Allergy, Instituto Nacional Enfermedades Respiratorias Ismael Cosío Villegas, Mexico City, Mexico
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Patel BS, Ravix J, Pabelick C, Prakash YS. Class C GPCRs in the airway. Curr Opin Pharmacol 2020; 51:19-28. [PMID: 32375079 DOI: 10.1016/j.coph.2020.04.002] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2020] [Revised: 03/17/2020] [Accepted: 04/02/2020] [Indexed: 02/07/2023]
Abstract
Understanding and targeting of GPCRs remain a critical aspect of airway pharmacology and therapeutics for diseases such as asthma or COPD. Most attention has been on the large Class A GPCRs towards improved bronchodilation and blunting of remodeling. Better known in the central or peripheral nervous system, there is increasing evidence that Class C GPCRs which include metabotropic glutamate and GABA receptors, the calcium sensing receptor, sweet/umami taste receptors and a number of orphan receptors, can contribute to airway structure and function. In this review, we will summarize current state of knowledge regarding the pharmacology of Class C GPCRs, their expression and potential functions in the airways, and the application of pharmacological agents targeting this group in the context of airway diseases.
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Affiliation(s)
- Brijeshkumar S Patel
- Department of Anesthesiologyand Perioperative Medicine, Mayo Clinic, Rochester, MN, United States
| | - Jovanka Ravix
- Department of Anesthesiologyand Perioperative Medicine, Mayo Clinic, Rochester, MN, United States
| | - Christina Pabelick
- Department of Anesthesiologyand Perioperative Medicine, Mayo Clinic, Rochester, MN, United States; Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, United States
| | - Y S Prakash
- Department of Anesthesiologyand Perioperative Medicine, Mayo Clinic, Rochester, MN, United States; Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, MN, United States.
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Yang J, Li N, Zhen Y, Huang Q. γ-aminobutyric acid alleviates LPS-induced acute lung injury in mice through upregulating type B receptors. Arch Med Sci 2019; 19:1116-1123. [PMID: 37560718 PMCID: PMC10408013 DOI: 10.5114/aoms.2019.89984] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2019] [Accepted: 10/23/2019] [Indexed: 08/11/2023] Open
Abstract
INTRODUCTION In recent years, studies have shown that GABA has a certain therapeutic effect on acute lung injury (ALI), but its specific mechanism has not been fully elucidated. The study was designed to investigate the protective effect and mechanism of γ-aminobutyric acid (GABA) on ALI induced by lipopolysaccharide (LPS) in mice. MATERIAL AND METHODS C57BL/6 mice were randomly divided into a control group, LPS group, LPS + GABA (10 mg/kg) group and LPS + dexamethasone (Dex, 5 mg/kg) group. The survival rate of each group was observed at different time points after modeling. The levels of tumor necrosis factor α (TNF-α), interleukin (IL) 1β, 10, myeloperoxidase (MPO) and the cell count and protein concentration in bronchoalveolar lavage fluid (BALF) were measured. Lung histopathology and the expression of GABA receptors were observed by HE staining and immunohistochemistry respectively. Lung water content was assessed by wet-dry weight ratio. RESULTS GABA could significantly improve the survival rate and prolong the survival time of animals, alleviate the degree of inflammatory injury and pulmonary edema, reduce the content of MPO, down-regulate the levels of pro-inflammatory cytokines IL-1β and TNF-α, and up-regulate the expression of anti-inflammatory cytokine IL-10. Moreover, GABA could significantly decrease the expression of type A receptors and enhance type B receptors. CONCLUSIONS GABA can effectively alleviate ALI induced by LPS in mice, and its effect may be related to the upregulation of type B receptors.
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Affiliation(s)
- Jing Yang
- Pediatric Department, Qilu Hospital of Shandong University (Qingdao), Qingdao, China
| | - Na Li
- Pediatric Department, Qilu Hospital of Shandong University (Qingdao), Qingdao, China
| | - Yuanyuan Zhen
- Pediatric Department, Qilu Hospital of Shandong University (Qingdao), Qingdao, China
| | - Qikun Huang
- Pediatric Department, Qilu Hospital of Shandong University (Qingdao), Qingdao, China
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Chen YC, Wu KC, Huang BM, So EC, Wang YK. Midazolam inhibits chondrogenesis via peripheral benzodiazepine receptor in human mesenchymal stem cells. J Cell Mol Med 2018. [PMID: 29516686 PMCID: PMC5908119 DOI: 10.1111/jcmm.13584] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Midazolam, a benzodiazepine derivative, is widely used for sedation and surgery. However, previous studies have demonstrated that Midazolam is associated with increased risks of congenital malformations, such as dwarfism, when used during early pregnancy. Recent studies have also demonstrated that Midazolam suppresses osteogenesis of mesenchymal stem cells (MSCs). Given that hypertrophic chondrocytes can differentiate into osteoblast and osteocytes and contribute to endochondral bone formation, the effect of Midazolam on chondrogenesis remains unclear. In this study, we applied a human MSC line, the KP cell, to serve as an in vitro model to study the effect of Midazolam on chondrogenesis. We first successfully established an in vitro chondrogenic model in a micromass culture or a 2D high‐density culture performed with TGF‐β‐driven chondrogenic induction medium. Treatment of the Midazolam dose‐dependently inhibited chondrogenesis, examined using Alcian blue‐stained glycosaminoglycans and the expression of chondrogenic markers, such as SOX9 and type II collagen. Inhibition of Midazolam by peripheral benzodiazepine receptor (PBR) antagonist PK11195 or small interfering RNA rescued the inhibitory effects of Midazolam on chondrogenesis. In addition, Midazolam suppressed transforming growth factor‐β‐induced Smad3 phosphorylation, and this inhibitory effect could be rescued using PBR antagonist PK11195. This study provides a possible explanation for Midazolam‐induced congenital malformations of the musculoskeletal system through PBR.
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Affiliation(s)
- Yung-Ching Chen
- Department of Cell Biology and Anatomy, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - King-Chuen Wu
- Department of Nursing, Chang Gung University of Science and Technology, Chia-Yi County, Taiwan.,Department of Anesthesiology, Chang Gung Memorial Hospital, Chiayi County, Taiwan
| | - Bu-Miin Huang
- Department of Cell Biology and Anatomy, College of Medicine, National Cheng Kung University, Tainan, Taiwan
| | - Edmund Cheung So
- Department of Anesthesiology, An-Nan Hospital, China Medical University, Tainan, Taiwan.,Department of Medicine, China Medical University, Taichung, Taiwan
| | - Yang-Kao Wang
- Department of Cell Biology and Anatomy, College of Medicine, National Cheng Kung University, Tainan, Taiwan
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Prakash YS. Emerging concepts in smooth muscle contributions to airway structure and function: implications for health and disease. Am J Physiol Lung Cell Mol Physiol 2016; 311:L1113-L1140. [PMID: 27742732 DOI: 10.1152/ajplung.00370.2016] [Citation(s) in RCA: 99] [Impact Index Per Article: 12.4] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/22/2016] [Accepted: 10/06/2016] [Indexed: 12/15/2022] Open
Abstract
Airway structure and function are key aspects of normal lung development, growth, and aging, as well as of lung responses to the environment and the pathophysiology of important diseases such as asthma, chronic obstructive pulmonary disease, and fibrosis. In this regard, the contributions of airway smooth muscle (ASM) are both functional, in the context of airway contractility and relaxation, as well as synthetic, involving production and modulation of extracellular components, modulation of the local immune environment, cellular contribution to airway structure, and, finally, interactions with other airway cell types such as epithelium, fibroblasts, and nerves. These ASM contributions are now found to be critical in airway hyperresponsiveness and remodeling that occur in lung diseases. This review emphasizes established and recent discoveries that underline the central role of ASM and sets the stage for future research toward understanding how ASM plays a central role by being both upstream and downstream in the many interactive processes that determine airway structure and function in health and disease.
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Affiliation(s)
- Y S Prakash
- Departments of Anesthesiology, and Physiology & Biomedical Engineering, Mayo Clinic, Rochester, Minnesota
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Luteolin Attenuates Airway Mucus Overproduction via Inhibition of the GABAergic System. Sci Rep 2016; 6:32756. [PMID: 27595800 PMCID: PMC5011760 DOI: 10.1038/srep32756] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2016] [Accepted: 08/15/2016] [Indexed: 12/21/2022] Open
Abstract
Airway mucus overproduction is one of the most common symptoms of asthma that causes severe clinical outcomes in patients. Despite the effectiveness of general asthma therapies, specific treatments that prevent mucus overproduction in asthma patients remain lacking. Recent studies have found that activation of GABAA receptors (GABAAR) is important for promoting mucus oversecretion in lung airway epithelia. Here, we report that luteolin, a natural flavonoid compound, suppresses mucus overproduction by functionally inhibiting the GABAergic system. This hypothesis was investigated by testing the effects of luteolin on goblet cell hyperplasia, excessive mucus secretion, and GABAergic transmission using histological and electrophysiological approaches. Our results showed that 10 mg/kg luteolin significantly decreased the number of goblet cells in the lung tissue and inhibited mucus overproduction in an in vivo asthma model induced by ovalbumin (OVA) in mice. Patch-clamp recordings showed that luteolin inhibited GABAAR-mediated currents in A549 cells. Furthermore, the inhibitory effects of luteolin on OVA-induced goblet cell hyperplasia and mucus overproduction were occluded by the GABAAR antagonist picrotoxin. In conclusion, our observations indicate that luteolin effectively attenuates mucus overproduction at least partially by inhibiting GABAARs, suggesting the potential for therapeutic administration of luteolin in the treatment of mucus overproduction in asthma patients.
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Danielsson J, Zaidi S, Kim B, Funayama H, Yim PD, Xu D, Worgall TS, Gallos G, Emala CW. Airway Epithelial Cell Release of GABA is Regulated by Protein Kinase A. Lung 2016; 194:401-8. [PMID: 26989055 DOI: 10.1007/s00408-016-9867-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/18/2015] [Accepted: 03/09/2016] [Indexed: 01/05/2023]
Abstract
INTRODUCTION γ-amino butyric acid (GABA) is not only the major inhibitory neurotransmitter in the central nervous system (CNS), but it also plays an important role in the lung, mediating airway smooth muscle relaxation and mucus production. As kinases such as protein kinase A (PKA) are known to regulate the release and reuptake of GABA in the CNS by GABA transporters, we hypothesized that β-agonists would affect GABA release from airway epithelial cells through activation of PKA. METHODS C57/BL6 mice received a pretreatment of a β-agonist or vehicle (PBS), followed by methacholine or PBS. Bronchoalveolar lavage (BAL) was collected and the amount of GABA was quantified using HPLC mass spectrometry. For in vitro studies, cultured BEAS-2B human airway epithelial cells were loaded with (3)H-GABA. (3)H-GABA released was measured during activation and inhibition of PKA and tyrosine kinase signaling pathways. RESULTS β-agonist pretreatment prior to methacholine challenge attenuated in vivo GABA release in mouse BAL and (3)H-GABA release from depolarized BEAS-2B cells. GABA release was also decreased in BEAS-2B cells by increases in cAMP but not by Epac or tyrosine kinase activation. CONCLUSION β-agonists decrease GABA release from airway epithelium through the activation of cAMP and PKA. This has important therapeutic implications as β-agonists and GABA are important mediators of both mucus production and airway smooth muscle tone.
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Affiliation(s)
- Jennifer Danielsson
- Department of Anesthesiology, Columbia University, 630 W 168th St., P&S Box 46, New York, NY, 10032, USA.
| | - Sarah Zaidi
- Department of Pediatrics, Columbia University, New York, NY, 10032, USA
| | - Benjamin Kim
- Department of Pathology and Cell Biology, Columbia University, New York, NY, 10032, USA
| | - Hiromi Funayama
- Department of Anesthesiology, Columbia University, 630 W 168th St., P&S Box 46, New York, NY, 10032, USA
- Department of Pediatric Dentistry, Tsurumi University School of Dental Medicine, Yokohama, Japan
| | - Peter D Yim
- Department of Anesthesiology, Columbia University, 630 W 168th St., P&S Box 46, New York, NY, 10032, USA
| | - Dingbang Xu
- Department of Anesthesiology, Columbia University, 630 W 168th St., P&S Box 46, New York, NY, 10032, USA
| | - Tilla S Worgall
- Department of Pathology and Cell Biology, Columbia University, New York, NY, 10032, USA
| | - George Gallos
- Department of Anesthesiology, Columbia University, 630 W 168th St., P&S Box 46, New York, NY, 10032, USA
| | - Charles W Emala
- Department of Anesthesiology, Columbia University, 630 W 168th St., P&S Box 46, New York, NY, 10032, USA
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Huang S, Mao J, Wei B, Pei G. The anti-spasticity drug baclofen alleviates collagen-induced arthritis and regulates dendritic cells. J Cell Physiol 2015; 230:1438-47. [PMID: 25556830 DOI: 10.1002/jcp.24884] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2014] [Accepted: 12/05/2014] [Indexed: 12/27/2022]
Abstract
Baclofen is used clinically as a drug that treats spasticity, which is a syndrome characterized by excessive contraction of the muscles and hyperflexia in the central nervous system (CNS), by activating GABA(B) receptors (GABA(B)Rs). Baclofen was recently reported to desensitize chemokine receptors and to suppress inflammation through the activation of GABA(B)Rs. GABA(B)Rs are expressed in various immune cells, but the functions of these receptors in autoimmune diseases remain largely unknown. In this study, we investigated the effects of baclofen in murine collagen-induced arthritis (CIA). Oral administration of baclofen alleviated the clinical development of CIA, with a reduced number of IL-17-producing T helper 17 (T(H)17) cells. In addition, baclofen treatment suppressed dendritic cell (DC)-primed T(H)17 cell differentiation by reducing the production of IL-6 by DCs in vitro. Furthermore, the pharmacological and genetic blockade of GABA(B)Rs in DCs weakened the effects of baclofen, indicating that GABA(B)Rs are the molecular targets of baclofen on DCs. Thus, our findings revealed a potential role for baclofen in the treatment of CIA, as well as a previously unknown signaling pathway that regulates DC function.
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Affiliation(s)
- Shichao Huang
- State Key Laboratory of Cell Biology, Institute of Biochemistry and Cell Biology, Shanghai Institutes for Biological Sciences, Graduate School of the Chinese Academy of Sciences, Chinese Academy of Sciences, Shanghai, P. R. China
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Wang XP, Cheng ZY, Schmid KL. GABAB receptors are expressed in human aortic smooth muscle cells and regulate the intracellular Ca(2+) concentration. Heart Vessels 2015; 30:249-57. [PMID: 24682435 DOI: 10.1007/s00380-014-0499-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/17/2013] [Accepted: 03/14/2014] [Indexed: 11/26/2022]
Abstract
The aim of this study was to investigate the expression of GABAB receptors, a subclass of receptors to the inhibitory neurotransmitter gamma-aminobutyric acid (GABAB), in human aortic smooth muscle cells (HASMCs), and to explore if altering receptor activation modified intracellular Ca(2+) concentration ([Ca(2+)]i) of HASMCs. Real-time PCR, western blots and immunofluorescence were used to determine the expression of GABABR1 and GABABR2 in cultured HASMCs. Immunohistochemistry was used to localize the two subunits in human left anterior descending artery (LAD). The effects of the GABAB receptor agonist baclofen on [Ca(2+)]i in cultured HASMCs were demonstrated using fluo-3. Both GABABR1 and GABABR2 mRNA and protein were identified in cultured HASMCs and antibody staining was also localized to smooth muscle cells of human LAD. 100 μM baclofen caused a transient increase of [Ca(2+)]i in cultured HASMCs regardless of whether Ca(2+) was added to the medium, and the effects were inhibited by pre-treatment with CGP46381 (selective GABAB receptor antagonist), pertussis toxin (a Gi/o protein inhibitor), and U73122 (a phospholipase C blocker). GABAB receptors are expressed in HASMCs and regulate the [Ca(2+)]i via a Gi/o-coupled receptor pathway and a phospholipase C activation pathway.
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MESH Headings
- Aorta/metabolism
- Calcium/metabolism
- Calcium Signaling/drug effects
- Cells, Cultured
- Enzyme Activation
- GABA Agonists/pharmacology
- GABA Antagonists/pharmacology
- GTP-Binding Protein alpha Subunits, Gi-Go/metabolism
- Humans
- Muscle, Smooth, Vascular/drug effects
- Muscle, Smooth, Vascular/metabolism
- Myocytes, Smooth Muscle/drug effects
- Myocytes, Smooth Muscle/metabolism
- Receptors, GABA-B/drug effects
- Receptors, GABA-B/genetics
- Receptors, GABA-B/metabolism
- Type C Phospholipases/metabolism
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Affiliation(s)
- Xu-Ping Wang
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Qilu Hospital, Shandong University, Jinan, Shandong, China
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Cheng ZY, Wang XP, Schmid KL, Han XG. GABAB1 and GABAB2 receptor subunits co-expressed in cultured human RPE cells regulate intracellular Ca2+ via Gi/o-protein and phospholipase C pathways. Neuroscience 2014; 280:254-61. [PMID: 25241062 DOI: 10.1016/j.neuroscience.2014.09.021] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Revised: 09/10/2014] [Accepted: 09/10/2014] [Indexed: 11/26/2022]
Abstract
GABAB receptors associate with Gi/o-proteins that regulate voltage-gated Ca(2+) channels and thus the intracellular Ca(2+) concentration ([Ca(2+)]i), there is also reported cross-regulation of phospholipase C. These associations have been studied extensively in the brain and also shown to occur in non-neural cells (e.g. human airway smooth muscle). More recently GABAB receptors have been observed in chick retinal pigment epithelium (RPE). The aims were to investigate whether the GABAB receptor subunits, GABAB1 and GABAB2, are co-expressed in cultured human RPE cells, and then determine if the GABAB receptor similarly regulates the [Ca(2+)]i of RPE cells and if phospholipase C is involved. Human RPE cells were cultured from five donor eye cups. Evidence for GABAB1 and GABAB2 mRNAs and proteins in the RPE cell cultures was investigated using real time polymerase chain reaction, western blots and immunofluorescence. The effects of the GABAB receptor agonist baclofen, antagonist CGP46381, a Gi/o-protein inhibitor pertussis toxin, and the phospholipase C inhibitor U73122 on [Ca(2+)]i in cultured human RPE were demonstrated using Fluo-3. Both GABAB1 and GABAB2 mRNA and protein were identified in cell cultures of human RPE; antibody staining was co-localized to the cell membrane and cytoplasm. One-hundred micromolars of baclofen caused a transient increase in the [Ca(2+)]i of RPE cells regardless of whether Ca(2+) was added to the buffer. Baclofen-induced increases in the [Ca(2+)]i were attenuated by pre-treatment with CGP46381, pertussis toxin, and U73122. GABAB1 and GABAB2 are co-expressed in cell cultures of human RPE. GABAB receptors in RPE regulate the [Ca(2+)]i via a Gi/o-protein and phospholipase C pathway.
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Affiliation(s)
- Z-Y Cheng
- Department of Ophthalmology, Qilu Hospital, Shandong University, Jinan, Shandong 250012, China.
| | - X-P Wang
- The Key Laboratory of Cardiovascular Remodeling and Function Research, Chinese Ministry of Education and Chinese Ministry of Health, Qilu Hospital, Shandong University, Jinan, Shandong 250012, China
| | - K L Schmid
- School of Optometry and Vision Science, Faculty of Health, and Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, QLD 4059, Australia
| | - X-G Han
- Department of Ophthalmology, The Second Hospital, Jinan, Shandong 250001, China
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Takano K, Yatabe MS, Abe A, Suzuki Y, Sanada H, Watanabe T, Kimura J, Yatabe J. Characteristic expressions of GABA receptors and GABA producing/transporting molecules in rat kidney. PLoS One 2014; 9:e105835. [PMID: 25188493 PMCID: PMC4154856 DOI: 10.1371/journal.pone.0105835] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 07/25/2014] [Indexed: 01/15/2023] Open
Abstract
Gamma-aminobutyric acid (GABA) is an important neurotransmitter, but recent reports have revealed the expression of GABAergic components in peripheral, non-neural tissues. GABA administration induces natriuresis and lowers blood pressure, suggesting renal GABA targets. However, systematic evaluation of renal GABAergic components has not been reported. In this study, kidney cortices of Wistar-Kyoto rats (WKY) were used to assay for messenger RNAs of GABA-related molecules using RT-PCR. In WKY kidney cortex, GABAA receptor subunits, α1, β3, δ, ε and π, in addition to both types of GABAB receptors, R1 and R2, and GABAC receptor ρ1 and ρ2 subunit mRNAs were detected. Kidney cortex also expressed mRNAs of glutamate decarboxylase (GAD) 65, GAD67, 4-aminobutyrate aminotransferase and GABA transporter, GAT2. Western blot and/or immunohistochemistry were performed for those molecules detected by RT-PCR. By immunofluorescent observation, co-staining of α1, β3, and π subunits was observed mainly on the apical side of cortical tubules, and immunoblot of kidney protein precipitated with π subunit antibody revealed α1 and β3 subunit co-assembly. This is the first report of GABAA receptor π subunit in the kidney. In summary, unique set of GABA receptor subunits and subtypes were found in rat kidney cortex. As GABA producing enzymes, transporters and degrading enzyme were also detected, a possible existence of local renal GABAergic system with an autocrine/paracrine mechanism is suggested.
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Affiliation(s)
- Kozue Takano
- Department of Pharmacology, Fukushima Medical University School of Medicine, Fukushima, Japan
| | - Midori Sasaki Yatabe
- Department of Pharmacology, Fukushima Medical University School of Medicine, Fukushima, Japan
- * E-mail: (MSY); (JY)
| | - Asami Abe
- Department of Pharmacology, Fukushima Medical University School of Medicine, Fukushima, Japan
| | - Yu Suzuki
- Department of Pharmacology, Fukushima Medical University School of Medicine, Fukushima, Japan
| | - Hironobu Sanada
- Division of Health Science Research, Fukushima Welfare Federation of Agricultural Cooperatives, Fukushima, Japan
| | - Tsuyoshi Watanabe
- Department of Nephrology, Hypertension, Diabetology, Endocrinology and Metabolism, Fukushima Medical University School of Medicine, Fukushima, Japan
| | - Junko Kimura
- Department of Pharmacology, Fukushima Medical University School of Medicine, Fukushima, Japan
| | - Junichi Yatabe
- Department of Pharmacology, Fukushima Medical University School of Medicine, Fukushima, Japan
- Department of Nephrology, Hypertension, Diabetology, Endocrinology and Metabolism, Fukushima Medical University School of Medicine, Fukushima, Japan
- * E-mail: (MSY); (JY)
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GABAB receptors expressed in human aortic endothelial cells mediate intracellular calcium concentration regulation and endothelial nitric oxide synthase translocation. BIOMED RESEARCH INTERNATIONAL 2014; 2014:871735. [PMID: 25114926 PMCID: PMC4119922 DOI: 10.1155/2014/871735] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Revised: 06/05/2014] [Accepted: 06/23/2014] [Indexed: 11/17/2022]
Abstract
GABAB receptors regulate the intracellular Ca2+ concentration ([Ca2+]i) in a number of cells (e.g., retina, airway epithelium and smooth muscle), but whether they are expressed in vascular endothelial cells and similarly regulate the [Ca2+]i is not known. The purpose of this study was to investigate the expression of GABAB receptors, a subclass of receptors to the inhibitory neurotransmitter γ-aminobutyric acid (GABA), in cultured human aortic endothelial cells (HAECs), and to explore if altering receptor activation modified [Ca2+]i and endothelial nitric oxide synthase (eNOS) translocation. Real-time PCR, western blots and immunofluorescence were used to determine the expression of GABAB1 and GABAB2 in cultured HAECs. The effects of GABAB receptors on [Ca2+]i in cultured HAECs were demonstrated using fluo-3. The influence of GABAB receptors on eNOS translocation was assessed by immunocytochemistry. Both GABAB1 and GABAB2 mRNA and protein were expressed in cultured HAECs, and the GABAB1 and GABAB2 proteins were colocated in the cell membrane and cytoplasm. One hundred μM baclofen caused a transient increase of [Ca2+]i and eNOS translocation in cultured HAECs, and the effects were attenuated by pretreatment with the selective GABAB receptor antagonists CGP46381 and CGP55845. GABAB receptors are expressed in HAECs and regulate the [Ca2+]i and eNOS translocation. Cultures of HAECs may be a useful in vitro model for the study of GABAB receptors and vascular biology.
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Fève M, Saliou JM, Zeniou M, Lennon S, Carapito C, Dong J, Van Dorsselaer A, Junier MP, Chneiweiss H, Cianférani S, Haiech J, Kilhoffer MC. Comparative expression study of the endo-G protein coupled receptor (GPCR) repertoire in human glioblastoma cancer stem-like cells, U87-MG cells and non malignant cells of neural origin unveils new potential therapeutic targets. PLoS One 2014; 9:e91519. [PMID: 24662753 PMCID: PMC3963860 DOI: 10.1371/journal.pone.0091519] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2013] [Accepted: 02/10/2014] [Indexed: 12/22/2022] Open
Abstract
Glioblastomas (GBMs) are highly aggressive, invasive brain tumors with bad prognosis and unmet medical need. These tumors are heterogeneous being constituted by a variety of cells in different states of differentiation. Among these, cells endowed with stem properties, tumor initiating/propagating properties and particularly resistant to chemo- and radiotherapies are designed as the real culprits for tumor maintenance and relapse after treatment. These cells, termed cancer stem-like cells, have been designed as prominent targets for new and more efficient cancer therapies. G-protein coupled receptors (GPCRs), a family of membrane receptors, play a prominent role in cell signaling, cell communication and crosstalk with the microenvironment. Their role in cancer has been highlighted but remains largely unexplored. Here, we report a descriptive study of the differential expression of the endo-GPCR repertoire in human glioblastoma cancer stem-like cells (GSCs), U-87 MG cells, human astrocytes and fetal neural stem cells (f-NSCs). The endo-GPCR transcriptome has been studied using Taqman Low Density Arrays. Of the 356 GPCRs investigated, 138 were retained for comparative studies between the different cell types. At the transcriptomic level, eight GPCRs were specifically expressed/overexpressed in GSCs. Seventeen GPCRs appeared specifically expressed in cells with stem properties (GSCs and f-NSCs). Results of GPCR expression at the protein level using mass spectrometry and proteomic analysis are also presented. The comparative GPCR expression study presented here gives clues for new pathways specifically used by GSCs and unveils novel potential therapeutic targets.
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Affiliation(s)
- Marie Fève
- Laboratoire d'Innovation Thérapeutique, UMR7200, Laboratoire d'Excellence Medalis, CNRS, Université de Strasbourg, Faculté de Pharmacie, Illkirch, France
| | - Jean-Michel Saliou
- Laboratoire de Spectrométrie de Masse BioOrganique, UMR7178, CNRS, Institut Pluridisciplinaire Hubert Curien, Université de Strasbourg, Strasbourg, France
| | - Maria Zeniou
- Laboratoire d'Innovation Thérapeutique, UMR7200, Laboratoire d'Excellence Medalis, CNRS, Université de Strasbourg, Faculté de Pharmacie, Illkirch, France
| | - Sarah Lennon
- Laboratoire de Spectrométrie de Masse BioOrganique, UMR7178, CNRS, Institut Pluridisciplinaire Hubert Curien, Université de Strasbourg, Strasbourg, France
| | - Christine Carapito
- Laboratoire de Spectrométrie de Masse BioOrganique, UMR7178, CNRS, Institut Pluridisciplinaire Hubert Curien, Université de Strasbourg, Strasbourg, France
| | - Jihu Dong
- Laboratoire d'Innovation Thérapeutique, UMR7200, Laboratoire d'Excellence Medalis, CNRS, Université de Strasbourg, Faculté de Pharmacie, Illkirch, France
| | - Alain Van Dorsselaer
- Laboratoire de Spectrométrie de Masse BioOrganique, UMR7178, CNRS, Institut Pluridisciplinaire Hubert Curien, Université de Strasbourg, Strasbourg, France
| | - Marie-Pierre Junier
- Neuroscience Paris Seine, UMR8246, Inserm U1130, Institut de Biologie Paris Seine, CNRS, Université Pierre et Marie Curie, Paris, France
| | - Hervé Chneiweiss
- Neuroscience Paris Seine, UMR8246, Inserm U1130, Institut de Biologie Paris Seine, CNRS, Université Pierre et Marie Curie, Paris, France
| | - Sarah Cianférani
- Laboratoire de Spectrométrie de Masse BioOrganique, UMR7178, CNRS, Institut Pluridisciplinaire Hubert Curien, Université de Strasbourg, Strasbourg, France
| | - Jacques Haiech
- Laboratoire d'Innovation Thérapeutique, UMR7200, Laboratoire d'Excellence Medalis, CNRS, Université de Strasbourg, Faculté de Pharmacie, Illkirch, France
| | - Marie-Claude Kilhoffer
- Laboratoire d'Innovation Thérapeutique, UMR7200, Laboratoire d'Excellence Medalis, CNRS, Université de Strasbourg, Faculté de Pharmacie, Illkirch, France
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16
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Prakash YS. Airway smooth muscle in airway reactivity and remodeling: what have we learned? Am J Physiol Lung Cell Mol Physiol 2013; 305:L912-33. [PMID: 24142517 PMCID: PMC3882535 DOI: 10.1152/ajplung.00259.2013] [Citation(s) in RCA: 159] [Impact Index Per Article: 14.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2013] [Accepted: 10/12/2013] [Indexed: 12/12/2022] Open
Abstract
It is now established that airway smooth muscle (ASM) has roles in determining airway structure and function, well beyond that as the major contractile element. Indeed, changes in ASM function are central to the manifestation of allergic, inflammatory, and fibrotic airway diseases in both children and adults, as well as to airway responses to local and environmental exposures. Emerging evidence points to novel signaling mechanisms within ASM cells of different species that serve to control diverse features, including 1) [Ca(2+)]i contractility and relaxation, 2) cell proliferation and apoptosis, 3) production and modulation of extracellular components, and 4) release of pro- vs. anti-inflammatory mediators and factors that regulate immunity as well as the function of other airway cell types, such as epithelium, fibroblasts, and nerves. These diverse effects of ASM "activity" result in modulation of bronchoconstriction vs. bronchodilation relevant to airway hyperresponsiveness, airway thickening, and fibrosis that influence compliance. This perspective highlights recent discoveries that reveal the central role of ASM in this regard and helps set the stage for future research toward understanding the pathways regulating ASM and, in turn, the influence of ASM on airway structure and function. Such exploration is key to development of novel therapeutic strategies that influence the pathophysiology of diseases such as asthma, chronic obstructive pulmonary disease, and pulmonary fibrosis.
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Affiliation(s)
- Y S Prakash
- Dept. of Anesthesiology, Mayo Clinic, 4-184 W Jos SMH, 200 First St. SW, Rochester, MN 55905.
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Gallos G, Townsend E, Yim P, Virag L, Zhang Y, Xu D, Bacchetta M, Emala CW. Airway epithelium is a predominant source of endogenous airway GABA and contributes to relaxation of airway smooth muscle tone. Am J Physiol Lung Cell Mol Physiol 2012. [PMID: 23204068 DOI: 10.1152/ajplung.00274.2012] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
Chronic obstructive pulmonary disease and asthma are characterized by hyperreactive airway responses that predispose patients to episodes of acute airway constriction. Recent studies suggest a complex paradigm of GABAergic signaling in airways that involves GABA-mediated relaxation of airway smooth muscle. However, the cellular source of airway GABA and mechanisms regulating its release remain unknown. We questioned whether epithelium is a major source of GABA in the airway and whether the absence of epithelium-derived GABA contributes to greater airway smooth muscle force. Messenger RNA encoding glutamic acid decarboxylase (GAD) 65/67 was quantitatively measured in human airway epithelium and smooth muscle. HPLC quantified GABA levels in guinea pig tracheal ring segments under basal or stimulated conditions with or without epithelium. The role of endogenous GABA in the maintenance of an acetylcholine contraction in human airway and guinea pig airway smooth muscle was assessed in organ baths. A 37.5-fold greater amount of mRNA encoding GAD 67 was detected in human epithelium vs. airway smooth muscle cells. HPLC confirmed that guinea pig airways with intact epithelium have a higher constitutive elution of GABA under basal or KCl-depolarized conditions compared with epithelium-denuded airway rings. Inhibition of GABA transporters significantly suppressed KCl-mediated release of GABA from epithelium-intact airways, but tetrodotoxin was without effect. The presence of intact epithelium had a significant GABAergic-mediated prorelaxant effect on the maintenance of contractile tone. Airway epithelium is a predominant cellular source of endogenous GABA in the airway and contributes significant prorelaxant GABA effects on airway smooth muscle force.
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Affiliation(s)
- George Gallos
- Department of Anesthesiology, College of Physicians and Surgeons, Columbia University, 622 W. 168 St., P&S Box 46, New York, NY 10032, USA.
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Determination of GABA(Aα1) and GABA (B1) receptor subunits expression in tissues of gilts during the late gestation. Mol Biol Rep 2012; 40:1377-84. [PMID: 23086273 DOI: 10.1007/s11033-012-2181-z] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/15/2012] [Accepted: 10/08/2012] [Indexed: 10/27/2022]
Abstract
GABA(Aα1) and GABA(B1) receptor subunits are responsible for most behavioral, physiological and pharmacological effects of GABA receptors. We investigated the expression of GABA(Aα1) and GABA(B1) receptor subunits in different tissues of gilts during late pregnancy in hot summer. The mRNA abundance of GABA(Aα1) receptor subunit in different tissues of gilts at d 90 and d 110 of gestation was as follows: d 90: brain > lung > liver > ovary > spleen > kidney > heart; d 110: brain > lung > spleen > liver > ovary > kidney > heart. And, the mRNA abundance of GABA(B1) receptor subunit was as follows: d 90: spleen > lung > brain > kidney > ovary > liver > heart; d 110: spleen > lung > kidney > brain > ovary > liver > heart. The results in this trial indicated that the GABA(Aα1) receptor subunit was abundantly expressed in brain, while GABA(B1) receptor subunit was abundant in spleen and lung of gilts during late gestation. There were no gestation stage-dependent effects on GABA(Aα1) and GABA(B1) receptor subunits expression in all tissues.
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Canning BJ, Mori N, Lehmann A. Antitussive effects of the peripherally restricted GABAB receptor agonist lesogaberan in guinea pigs: comparison to baclofen and other GABAB receptor-selective agonists. COUGH 2012; 8:7. [PMID: 23025757 PMCID: PMC3520872 DOI: 10.1186/1745-9974-8-7] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Accepted: 09/07/2012] [Indexed: 12/17/2022]
Abstract
UNLABELLED BACKGROUND Gastroesophageal reflux disease (GERD) is a common cause of chronic cough. Both acid and nonacid reflux is thought to play a role in the initiation of coughing and cough hypersensitivity. The GABAB receptor agonist lesogaberan was developed as a peripherally restricted anti-reflux therapy that reduces the frequency of transient lower esophageal sphincter relaxations (TLESR; the major cause of reflux) in animals and in patients with GERD. GABAB receptor agonists have also been shown to possess antitussive effects in patients and in animals independent of their effects on TLESR, suggesting that lesogaberan may be a promising treatment for chronic cough. METHODS We have assessed the direct antitussive effects of lesogaberan (AZD3355). The effects of other GABAB receptor agonists were also determined. Coughing was evoked in awake guinea pigs using aerosol challenges with citric acid. RESULTS Lesogaberan dose-dependently inhibited citric acid evoked coughing in guinea pigs. Comparable effects of the GABAB receptor agonists baclofen and 3-aminopropylphosphinic acid (3-APPiA) on cough were also observed. Baclofen produced obvious signs of sedation and respiratory depression. By contrast, both lesogaberan and 3-APPiA (both inactivated centrally by GABA transporters) were devoid of sedative effects and did not alter respiratory rate. CONCLUSIONS Together, the data suggest that lesogaberan and related GABAB receptor agonists may hold promise as safe and effective antitussive agents largely devoid of CNS side effects.
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Affiliation(s)
- Brendan J Canning
- Johns Hopkins Asthma and Allergy Center, 5501 Hopkins Bayview Circle, Baltimore, Maryland, 21224, USA.
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Effects of anesthetic regimes on inflammatory responses in a rat model of acute lung injury. Intensive Care Med 2012; 38:1548-55. [PMID: 22711173 DOI: 10.1007/s00134-012-2610-4] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2011] [Accepted: 05/17/2012] [Indexed: 12/30/2022]
Abstract
PURPOSE Gamma-aminobutyric acid (GABA) is the major inhibitory neurotransmitter through activation of GABA receptors. Volatile anesthetics activate type-A (GABA(A)) receptors resulting in inhibition of synaptic transmission. Lung epithelial cells have been recently found to express GABA(A) receptors that exert anti-inflammatory properties. We hypothesized that the volatile anesthetic sevoflurane (SEVO) attenuates lung inflammation through activation of lung epithelial GABA(A) receptors. METHODS Sprague-Dawley rats were anesthetized with SEVO or ketamine/xylazine (KX). Acute lung inflammation was induced by intratracheal instillation of endotoxin, followed by mechanical ventilation for 4 h at a tidal volume of 15 mL/kg without positive end-expiratory pressure (two-hit lung injury model). To examine the specific effects of GABA, healthy human lung epithelial cells (BEAS-2B) were challenged with endotoxin in the presence and absence of GABA with and without addition of the GABA(A) receptor antagonist picrotoxin. RESULTS Anesthesia with SEVO improved oxygenation and reduced pulmonary cytokine responses compared to KX. This phenomenon was associated with increased expression of the π subunit of GABA(A) receptors and glutamic acid decarboxylase (GAD). The endotoxin-induced cytokine release from BEAS-2B cells was attenuated by the treatment with GABA, which was reversed by the administration of picrotoxin. CONCLUSION Anesthesia with SEVO suppresses pulmonary inflammation and thus protects the lung from the two-hit injury. The anti-inflammatory effect of SEVO is likely due to activation of pulmonary GABA(A) signaling pathways.
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Cheng ZY, Chebib M, Schmid KL. Identification of GABA receptors in chick cornea. Mol Vis 2012; 18:1107-14. [PMID: 22605922 PMCID: PMC3351410] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2012] [Accepted: 04/27/2012] [Indexed: 11/24/2022] Open
Abstract
PURPOSE The cornea has an important role in vision, is highly innervated and many neurotransmitter receptors are present, e.g., muscarine, melatonin, and dopamine receptors. γ-aminobutyric acid (GABA) is the most important inhibitory neurotransmitter in the retina and central nervous system, but it is unknown whether GABA receptors are present in cornea. The aim of this study was to determine if GABA receptors are located in chick cornea. METHODS Corneal tissues were collected from 25, 12-day-old chicks. Real time PCR, western blot, and immunohistochemistry were used to determine whether alpha(1) GABA(A), GABA(B), and rho(1) GABA(C) receptors were expressed and located in chick cornea. RESULTS Corneal tissue was positive for alpha(1) GABA(A) and rho(1) GABA(C) receptor mRNA (PCR) and protein (western blot) expression but was negative for GABA(B) receptor mRNA and protein. Alpha(1) GABA(A) and rho(1) GABA(C) receptor protein labeling was observed in the corneal epithelium using immunohistochemistry. CONCLUSIONS These investigations clearly show that chick cornea possesses alpha(1) GABA(A), and rho(1) GABA(C) receptors, but not GABA(B) receptors. The purpose of the alpha(1) GABA(A) and rho(1) GABA(C) receptors in cornea is a fascinating unexplored question.
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Affiliation(s)
- Zhen-Ying Cheng
- Myopia Center, Department of Ophthalmology, Qilu Hospital, Shandong University, Jinan, Shandong, China
| | - Mary Chebib
- Faculty of Pharmacy, University of Sydney, Sydney, New South Wales, Australia
| | - Katrina L. Schmid
- School of Optometry and Vision Science, Faculty of Health, and Vision Improvement Domain, Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia
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Jiang X, Su L, Zhang Q, He C, Zhang Z, Yi P, Liu J. GABAB receptor complex as a potential target for tumor therapy. J Histochem Cytochem 2012; 60:269-79. [PMID: 22266766 DOI: 10.1369/0022155412438105] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
γ-Aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the vertebrate central nervous system. Metabotropic GABA(B) receptors are heterodimeric G-protein-coupled receptors (GPCRs) consisting of GABA(B1) and GABA(B2) subunits. The intracellular C-terminal domains of GABA(B) receptors are involved in heterodimerization, oligomerization, and association with other proteins, which results in a large receptor complex. Multiple splice variants of the GABA(B1) subunit have been identified in which GABA(B1a) and GABA(B1b) are the most abundant isoforms in the nervous system. Isoforms GABA(B1c) through GABA(B1n) are minor isoforms and are detectable only at mRNA levels. Some of the minor isoforms have been detected in peripheral tissues and encode putative soluble proteins with C-terminal truncations. Interestingly, increased expression of GABA(B) receptors has been detected in several human cancer cells and tissues. Moreover, GABA(B) receptor agonist baclofen inhibited tumor growth in rat models. GABA(B) receptor activation not only induces suppressing the proliferation and migration of various human tumor cells but also results in inactivation of CREB (cAMP-responsive element binding protein) and ERK in tumor cells. Their structural complexity makes it possible to disrupt the functions of GABA(B) receptors in various ways, raising GABA(B) receptor diversity as a potential therapeutic target in some human cancers.
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Affiliation(s)
- Xinnong Jiang
- Sino-France Laboratory for Drug Screening, Key Laboratory of Molecular Biophysics of Ministry of Education, School of Life Science and Technology, Huazhong University of Science and Technology, Wuhan, P. R. China.
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Gallos G, Yim P, Chang S, Zhang Y, Xu D, Cook JM, Gerthoffer WT, Emala CW. Targeting the restricted α-subunit repertoire of airway smooth muscle GABAA receptors augments airway smooth muscle relaxation. Am J Physiol Lung Cell Mol Physiol 2011; 302:L248-56. [PMID: 21949156 DOI: 10.1152/ajplung.00131.2011] [Citation(s) in RCA: 53] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
The prevalence of asthma has taken on pandemic proportions. Since this disease predisposes patients to severe acute airway constriction, novel mechanisms capable of promoting airway smooth muscle relaxation would be clinically valuable. We have recently demonstrated that activation of endogenous airway smooth muscle GABA(A) receptors potentiates β-adrenoceptor-mediated relaxation, and molecular analysis of airway smooth muscle reveals that the α-subunit component of these GABA(A) receptors is limited to the α(4)- and α(5)-subunits. We questioned whether ligands with selective affinity for these GABA(A) receptors could promote relaxation of airway smooth muscle. RT-PCR analysis of GABA(A) receptor subunits was performed on RNA isolated by laser capture microdissection from human and guinea pig airway smooth muscle. Membrane potential and chloride-mediated current were measured in response to GABA(A) subunit-selective agonists in cultured human airway smooth muscle cells. Functional relaxation of precontracted guinea pig tracheal rings was assessed in the absence and presence of the α(4)-subunit-selective GABA(A) receptor agonists: gaboxadol, taurine, and a novel 8-methoxy imidazobenzodiazepine (CM-D-45). Only messenger RNA encoding the α(4)- and α(5)-GABA(A) receptor subunits was identified in RNA isolated by laser capture dissection from guinea pig and human airway smooth muscle tissues. Activation of airway smooth muscle GABA(A) receptors with agonists selective for these subunits resulted in appropriate membrane potential changes and chloride currents and promoted relaxation of airway smooth muscle. In conclusion, selective subunit targeting of endogenous airway smooth muscle-specific GABA(A) receptors may represent a novel therapeutic option for patients in severe bronchospasm.
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Affiliation(s)
- George Gallos
- Dept. of Anesthesiology, College of Physicians and Surgeons of Columbia University, 622 W. 168 St.; P&S Box 46, New York, NY 10032, USA.
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Mizuta K, Mizuta F, Xu D, Masaki E, Panettieri RA, Emala CW. Gi-coupled γ-aminobutyric acid-B receptors cross-regulate phospholipase C and calcium in airway smooth muscle. Am J Respir Cell Mol Biol 2011; 45:1232-8. [PMID: 21719794 DOI: 10.1165/rcmb.2011-0088oc] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
γ-aminobutyric acid (GABA) is the major inhibitory neurotransmitter in the mammalian central nervous system, and exerts its actions via both ionotropic (GABA(A)) and metabotropic (GABA(B)) receptors. Although the functional expression of GABA(B) receptors coupled to the G(i) protein was reported for airway smooth muscle, the role of GABA(B) receptors in airway responsiveness remains unclear. We investigated whether G(i)-coupled GABA(B) receptors cross-regulate phospholipase C (PLC), an enzyme classically regulated by G(q)-coupled receptors in human airway smooth muscle cells. Both the GABA(B)-selective agonist baclofen and the endogenous ligand GABA significantly increased the synthesis of inositol phosphate, whereas GABA(A) receptor agonists, muscimol, and 4,5,6,7-tetrahydroisoxazolo[5,4-c]pyridin-3-ol exerted no effect. The baclofen-induced synthesis of inositol phosphate and transient increases in [Ca(2+)](i) were blocked by CGP35348 and CGP55845 (selective GABA(B) antagonists), pertussis toxin (PTX, which inactivates the G(i) protein), gallein (a G(βγ) signaling inhibitor), U73122 (an inhibitor of PLC-β), and xestospongin C, an inositol 1,4,5-triphosphate receptor blocker. Baclofen also potentiated the bradykinin-induced synthesis of inositol phosphate and transient increases in [Ca(2+)](i), which were blocked by CGP35348 or PTX. Moreover, baclofen potentiated the substance P-induced contraction of airway smooth muscle in isolated guinea pig tracheal rings. In conclusion, the stimulation of GABA(B) receptors in human airway smooth muscle cells rapidly mobilizes intracellular Ca(2+) stores by the synthesis of inositol phosphate via the activation of PLC-β, which is stimulated by G(βγ) protein liberated from G(i) proteins coupled to GABA(B) receptors. Furthermore, crosstalk between GABA(B) receptors and G(q)-coupled receptors potentiates the synthesis of inositol phosphate, transient increases in [Ca(2+)](i), and smooth muscle contraction through G(i) proteins.
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Affiliation(s)
- Kentaro Mizuta
- Department of Anesthesiology, College of Physicians and Surgeons, Columbia University, New York, NY 10032, USA
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Zaidi S, Gallos G, Yim PD, Xu D, Sonett JR, Panettieri RA, Gerthoffer W, Emala CW. Functional expression of γ-amino butyric acid transporter 2 in human and guinea pig airway epithelium and smooth muscle. Am J Respir Cell Mol Biol 2010; 45:332-9. [PMID: 21057105 DOI: 10.1165/rcmb.2010-0177oc] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022] Open
Abstract
γ-Amino butyric acid (GABA) is a primary inhibitory neurotransmitter in the central nervous system, and is classically released by fusion of synaptic vesicles with the plasma membrane or by egress via GABA transporters (GATs). Recently, a GABAergic system comprised of GABA(A) and GABA(B) receptors has been identified on airway epithelial and smooth muscle cells that regulate mucus secretion and contractile tone of airway smooth muscle (ASM). In addition, the enzyme that synthesizes GABA, glutamic acid decarboxylase, has been identified in airway epithelial cells; however, the mechanism(s) by which this synthesized GABA is released from epithelial intracellular stores is unknown. We questioned whether any of the four known isoforms of GATs are functionally expressed in ASM or epithelial cells. We detected mRNA and protein expression of GAT2 and -4, and isoforms of glutamic acid decarboxylase in native and cultured human ASM and epithelial cells. In contrast, mRNA encoding vesicular GAT (VGAT), the neuronal GABA transporter, was not detected. Functional inhibition of (3)H-GABA uptake was demonstrated using GAT2 and GAT4/betaine-GABA transporter 1 (BGT1) inhibitors in both human ASM and epithelial cells. These results demonstrate that two isoforms of GATs, but not VGAT, are expressed in both airway epithelial and smooth muscle cells. They also provide a mechanism by which locally synthesized GABA can be released from these cells into the airway to activate GABA(A) channels and GABA(B) receptors, with subsequent autocrine and/or paracrine signaling effects on airway epithelium and ASM.
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Affiliation(s)
- Sarah Zaidi
- Department of Pediatrics, College of Physicians and Surgeons of Columbia University, New York, New York 10032, USA
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Wang G, Wang R, Ferris B, Salit J, Strulovici-Barel Y, Hackett NR, Crystal RG. Smoking-mediated up-regulation of GAD67 expression in the human airway epithelium. Respir Res 2010; 11:150. [PMID: 21034448 PMCID: PMC2988726 DOI: 10.1186/1465-9921-11-150] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2009] [Accepted: 10/29/2010] [Indexed: 01/08/2023] Open
Abstract
Background The production of gamma-amino butyric acid (GABA) is dependent on glutamate decarboxylases (GAD65 and GAD67), the enzymes that catalyze the decarboxylation of glutamate to GABA. Based on studies suggesting a role of the airway epithelial GABAergic system in asthma-related mucus overproduction, we hypothesized that cigarette smoking, another disorder associated with increased mucus production, may modulate GABAergic system-related gene expression levels in the airway epithelium. Methods We assessed expression of the GABAergic system in human airway epithelium obtained using bronchoscopy to sample the epithelium and microarrays to evaluate gene expression. RT-PCR was used to confirm gene expression of GABAergic system gene in large and small airway epithelium from heathy nonsmokers and healthy smokers. The differences in the GABAergic system gene was further confirmed by TaqMan, immunohistochemistry and Western analysis. Results The data demonstrate there is a complete GABAergic system expressed in the large and small human airway epithelium, including glutamate decarboxylase, GABA receptors, transporters and catabolism enzymes. Interestingly, of the entire GABAergic system, smoking modified only the expression of GAD67, with marked up-regulation of GAD67 gene expression in both large (4.1-fold increase, p < 0.01) and small airway epithelium of healthy smokers (6.3-fold increase, p < 0.01). At the protein level, Western analysis confirmed the increased expression of GAD67 in airway epithelium of healthy smokers compared to healthy nonsmokers (p < 0.05). There was a significant positive correlation between GAD67 and MUC5AC gene expression in both large and small airway epithelium (p < 0.01), implying a link between GAD67 and mucin overproduction in association with smoking. Conclusions In the context that GAD67 is the rate limiting enzyme in GABA synthesis, the correlation of GAD67 gene expression with MUC5AC expressions suggests that the up-regulation of airway epithelium expression of GAD67 may contribute to the increase in mucus production observed in association with cigarette smoking. Trial registration NCT00224198; NCT00224185
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Affiliation(s)
- Guoqing Wang
- Department of Genetic Medicine, Weill Cornell Medical College, New York, New York, USA
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Zhou Z, Sun H, Li X, Li Y, Zhao S, Zhang D, Yao Z, Li J. A local GABAergic system is functionally expressed in human fallopian tube. Biochem Biophys Res Commun 2010; 398:237-41. [DOI: 10.1016/j.bbrc.2010.06.066] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2010] [Accepted: 06/16/2010] [Indexed: 11/15/2022]
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Prachayasi S, Wongsawatk O, Worachartc A, Ruchirawat S, Prachayasi V. Vasorelaxation and Superoxide Scavenging Activities of Orotic Acid. INT J PHARMACOL 2010. [DOI: 10.3923/ijp.2010.413.418] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
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Hirota JA, Budelsky A, Smith D, Lipsky B, Ellis R, Xiang YY, Lu WY, Inman MD. The role of interleukin-4Ralpha in the induction of glutamic acid decarboxylase in airway epithelium following acute house dust mite exposure. Clin Exp Allergy 2010; 40:820-30. [PMID: 20337645 DOI: 10.1111/j.1365-2222.2010.03458.x] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
Background Asthma is a disease characterized by airway inflammation, remodelling and dysfunction. Airway inflammation contributes to remodelling, a term that is used to describe structural changes including goblet cell metaplasia (GCM), matrix deposition, and smooth muscle hyperplasia/hypertrophy. GCM has been implicated in asthma mortality by contributing to mucus plugs and leading to asphyxiation. In animal models, this process is highly dependent on IL-13. Recently, we have described an IL-13-dependent up-regulation of a GABAergic signalling system in airway epithelium that contributes to GCM. The mechanism by which IL-13 up-regulates GABA signalling in airway epithelium is unknown. Objectives To test the hypothesis that IL-4Ralpha signalling is required for allergen induced up-regulation of GABAergic signalling and GCM. Methods BALB/c mice were exposed to an acute house dust mite (HDM) protocol and received vehicle, anti-IL-4Ralpha-monoclonal antibody, or control antibody. Outcomes included airway responses to inhaled methacholine (MCh), histology for eosinophilia and GCM, phosphorylated STAT6 levels using immunohistochemistry and immunoblot, and glutamic acid decarboxylase (GAD) 65/67 and GABA(A)beta(2/3) receptor subunit expression using confocal microscopy. Results Acute HDM exposure resulted in increased airway responses to MCh, lung eosinophilia, STAT6 phosphorylation, elevations in GAD65/67 and GABA(A)beta(2/3) receptor expression, and GCM that were inhibited with anti-IL-4Ralpha-monoclonal treatment. Control antibody had no effect. Conclusion The IL-4Ralpha is required for allergen-induced up-regulation of a GABAergic system in airway epithelium implicated in GCM following acute HDM exposure.
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Affiliation(s)
- J A Hirota
- Firestone Institute for Respiratory Health, St. Joseph's Hospital, McMaster University, 50 Charlton Avenue East, Hamilton, Ontario, Canada
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Tu H, Xu C, Zhang W, Liu Q, Rondard P, Pin JP, Liu J. GABAB receptor activation protects neurons from apoptosis via IGF-1 receptor transactivation. J Neurosci 2010; 30:749-59. [PMID: 20071540 PMCID: PMC6633015 DOI: 10.1523/jneurosci.2343-09.2010] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2009] [Revised: 11/23/2009] [Accepted: 11/25/2009] [Indexed: 12/17/2022] Open
Abstract
The G-protein-coupled receptors (GPCRs) and receptor tyrosine kinases (RTKs) play key roles in cell-cell communication. Several studies revealed important synergisms between these two types of receptors, with some of the actions of either receptor being mediated through transactivation of the other. Among the large GPCR family, GABA(B) receptor is activated by the neurotransmitter GABA, and is expressed in most neurons where it mediates slow and prolonged inhibition of synaptic transmission. Here we show that this receptor is involved in the regulation of life and death decisions of cerebellar granule neurons (CGNs). We show that specific activation of GABA(B) receptor can protect neurons from apoptosis through a mechanism that involves transactivation of the IGF-1 receptor (IGF-1R). Further work demonstrated that this cross talk was dependent on G(i/o)-protein, PLC, cytosolic Ca(2+), and FAK1 but independent of PKC, while IGF-1R-induced signaling involved Src kinase, PI3 kinase, and Akt activation. These results reveal a new function for this important GPCR and further highlight the importance of functional cross-talk networks between GPCRs and RTKs. Our results reveal GABA(B) receptor as a potential drug target for the treatment of neurodegenerative disorders.
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Affiliation(s)
- Haijun Tu
- Sino-France Laboratory for Drug Screening, Key Laboratory of Molecular Biophysics of Ministry of Education, School of Life Science and Technology, Huazhong University of Science and Technology, 430074 Wuhan, Hubei, China, and
| | - Chanjuan Xu
- Sino-France Laboratory for Drug Screening, Key Laboratory of Molecular Biophysics of Ministry of Education, School of Life Science and Technology, Huazhong University of Science and Technology, 430074 Wuhan, Hubei, China, and
| | - Wenhua Zhang
- Sino-France Laboratory for Drug Screening, Key Laboratory of Molecular Biophysics of Ministry of Education, School of Life Science and Technology, Huazhong University of Science and Technology, 430074 Wuhan, Hubei, China, and
| | - Qiuyao Liu
- Sino-France Laboratory for Drug Screening, Key Laboratory of Molecular Biophysics of Ministry of Education, School of Life Science and Technology, Huazhong University of Science and Technology, 430074 Wuhan, Hubei, China, and
| | - Philippe Rondard
- Centre National de la Recherche Scientifique, UMR5203, Institut de Génomique Fonctionnelle, Inserm, U661 and Université Montpellier 1, 2, Montpellier F-34000, France
| | - Jean-Philippe Pin
- Centre National de la Recherche Scientifique, UMR5203, Institut de Génomique Fonctionnelle, Inserm, U661 and Université Montpellier 1, 2, Montpellier F-34000, France
| | - Jianfeng Liu
- Sino-France Laboratory for Drug Screening, Key Laboratory of Molecular Biophysics of Ministry of Education, School of Life Science and Technology, Huazhong University of Science and Technology, 430074 Wuhan, Hubei, China, and
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Endogenous gamma-aminobutyric acid modulates tonic guinea pig airway tone and propofol-induced airway smooth muscle relaxation. Anesthesiology 2009; 110:748-58. [PMID: 19322939 DOI: 10.1097/aln.0b013e31819c44e1] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
BACKGROUND Emerging evidence indicates that an endogenous autocrine/paracrine system involving gamma-aminobutyric acid (GABA) is present in airways. GABAA channels, GABAB receptors, and the enzyme that synthesizes GABA have been identified in airway epithelium and smooth muscle. However, the endogenous ligand itself, GABA, has not been measured in airway tissues. The authors sought to demonstrate that GABA is released in response to contractile agonists and tonically contributes a prorelaxant component to contracted airway smooth muscle. METHODS The amount and cellular localization of GABA in upper guinea pig airways under resting and contracted tone was determined by high pressure liquid chromatography and immunohistochemistry, respectively. The contribution that endogenous GABA imparts on the maintenance of airway smooth muscle acetylcholine-induced contraction was assessed in intact guinea pig airway tracheal rings using selective GABAA antagonism (gabazine) under resting or acetylcholine-contracted conditions. The ability of an allosteric agent (propofol) to relax a substance P-induced relaxation in an endogenous GABA-dependent manner was assessed. RESULTS GABA levels increased and localized to airway smooth muscle after contractile stimuli in guinea pig upper airways. Acetylcholine-contracted guinea pig tracheal rings exhibited an increase in contracted force upon addition of the GABAA antagonist gabazine that was subsequently reversed by the addition of the GABAA agonist muscimol. Propofol dose-dependently relaxed a substance P contraction that was blocked by gabazine. CONCLUSION These studies demonstrate that GABA is endogenously present and increases after contractile stimuli in guinea pig upper airways and that endogenous GABA contributes a tonic prorelaxant component in the maintenance of airway smooth muscle tone.
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Abstract
Asthma often occurs as a result of immune-based inflammatory responses, which consequently cause pathological changes in airway structural cells. However, the underlying mechanisms of airway pathology in asthma are still not fully understood. Our recent studies revealed a critical role of gamma-aminobutyric acid (GABA) signalling pathway in the airway epithelium of allergic asthma through its ability to stimulate mucus production. This review briefly describes the GABAergic signalling system and its role in the regulation of mucus protein production in bronchial airway epithelial cells.
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Affiliation(s)
- W-Y Lu
- Departments of Anesthesia and Physiology, University of Toronto, ON, Canada.
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