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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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Galla L, Vajente N, Pendin D, Pizzo P, Pozzan T, Greotti E. Generation and Characterization of a New FRET-Based Ca 2+ Sensor Targeted to the Nucleus. Int J Mol Sci 2021; 22:ijms22189945. [PMID: 34576104 PMCID: PMC8467696 DOI: 10.3390/ijms22189945] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2021] [Revised: 09/09/2021] [Accepted: 09/12/2021] [Indexed: 12/17/2022] Open
Abstract
Calcium (Ca2+) exerts a pivotal role in controlling both physiological and detrimental cellular processes. This versatility is due to the existence of a cell-specific molecular Ca2+ toolkit and its fine subcellular compartmentalization. Study of the role of Ca2+ in cellular physiopathology greatly benefits from tools capable of quantitatively measuring its dynamic concentration ([Ca2+]) simultaneously within organelles and in the cytosol to correlate localized and global [Ca2+] changes. To this aim, as nucleoplasm Ca2+ changes mirror those of the cytosol, we generated a novel nuclear-targeted version of a Föster resonance energy transfer (FRET)-based Ca2+ probe. In particular, we modified the previously described nuclear Ca2+ sensor, H2BD3cpv, by substituting the donor ECFP with mCerulean3, a brighter and more photostable fluorescent protein. The thorough characterization of this sensor in HeLa cells demonstrated that it significantly improved the brightness and photostability compared to the original probe, thus obtaining a probe suitable for more accurate quantitative Ca2+ measurements. The affinity for Ca2+ was determined in situ. Finally, we successfully applied the new probe to confirm that cytoplasmic and nucleoplasmic Ca2+ levels were similar in both resting conditions and upon cell stimulation. Examples of simultaneous monitoring of Ca2+ signal dynamics in different subcellular compartments in the very same cells are also presented.
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Affiliation(s)
- Luisa Galla
- Neuroscience Institute, National Research Council (CNR), 35131 Padua, Italy; (L.G.); (N.V.); (D.P.); (P.P.); (T.P.)
- Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy
| | - Nicola Vajente
- Neuroscience Institute, National Research Council (CNR), 35131 Padua, Italy; (L.G.); (N.V.); (D.P.); (P.P.); (T.P.)
- Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy
| | - Diana Pendin
- Neuroscience Institute, National Research Council (CNR), 35131 Padua, Italy; (L.G.); (N.V.); (D.P.); (P.P.); (T.P.)
- Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy
| | - Paola Pizzo
- Neuroscience Institute, National Research Council (CNR), 35131 Padua, Italy; (L.G.); (N.V.); (D.P.); (P.P.); (T.P.)
- Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy
| | - Tullio Pozzan
- Neuroscience Institute, National Research Council (CNR), 35131 Padua, Italy; (L.G.); (N.V.); (D.P.); (P.P.); (T.P.)
- Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy
- Venetian Institute of Molecular Medicine (VIMM), 35131 Padua, Italy
| | - Elisa Greotti
- Neuroscience Institute, National Research Council (CNR), 35131 Padua, Italy; (L.G.); (N.V.); (D.P.); (P.P.); (T.P.)
- Department of Biomedical Sciences, University of Padua, 35131 Padua, Italy
- Correspondence:
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Dynamic Control of Synaptic Adhesion and Organizing Molecules in Synaptic Plasticity. Neural Plast 2017; 2017:6526151. [PMID: 28255461 PMCID: PMC5307005 DOI: 10.1155/2017/6526151] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2016] [Accepted: 12/13/2016] [Indexed: 12/13/2022] Open
Abstract
Synapses play a critical role in establishing and maintaining neural circuits, permitting targeted information transfer throughout the brain. A large portfolio of synaptic adhesion/organizing molecules (SAMs) exists in the mammalian brain involved in synapse development and maintenance. SAMs bind protein partners, forming trans-complexes spanning the synaptic cleft or cis-complexes attached to the same synaptic membrane. SAMs play key roles in cell adhesion and in organizing protein interaction networks; they can also provide mechanisms of recognition, generate scaffolds onto which partners can dock, and likely take part in signaling processes as well. SAMs are regulated through a portfolio of different mechanisms that affect their protein levels, precise localization, stability, and the availability of their partners at synapses. Interaction of SAMs with their partners can further be strengthened or weakened through alternative splicing, competing protein partners, ectodomain shedding, or astrocytically secreted factors. Given that numerous SAMs appear altered by synaptic activity, in vivo, these molecules may be used to dynamically scale up or scale down synaptic communication. Many SAMs, including neurexins, neuroligins, cadherins, and contactins, are now implicated in neuropsychiatric and neurodevelopmental diseases, such as autism spectrum disorder, schizophrenia, and bipolar disorder and studying their molecular mechanisms holds promise for developing novel therapeutics.
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