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Fu X, Kim HS. Dentin Mechanobiology: Bridging the Gap between Architecture and Function. Int J Mol Sci 2024; 25:5642. [PMID: 38891829 PMCID: PMC11171917 DOI: 10.3390/ijms25115642] [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: 04/30/2024] [Revised: 05/20/2024] [Accepted: 05/20/2024] [Indexed: 06/21/2024] Open
Abstract
It is remarkable how teeth maintain their healthy condition under exceptionally high levels of mechanical loading. This suggests the presence of inherent mechanical adaptation mechanisms within their structure to counter constant stress. Dentin, situated between enamel and pulp, plays a crucial role in mechanically supporting tooth function. Its intermediate stiffness and viscoelastic properties, attributed to its mineralized, nanofibrous extracellular matrix, provide flexibility, strength, and rigidity, enabling it to withstand mechanical loading without fracturing. Moreover, dentin's unique architectural features, such as odontoblast processes within dentinal tubules and spatial compartmentalization between odontoblasts in dentin and sensory neurons in pulp, contribute to a distinctive sensory perception of external stimuli while acting as a defensive barrier for the dentin-pulp complex. Since dentin's architecture governs its functions in nociception and repair in response to mechanical stimuli, understanding dentin mechanobiology is crucial for developing treatments for pain management in dentin-associated diseases and dentin-pulp regeneration. This review discusses how dentin's physical features regulate mechano-sensing, focusing on mechano-sensitive ion channels. Additionally, we explore advanced in vitro platforms that mimic dentin's physical features, providing deeper insights into fundamental mechanobiological phenomena and laying the groundwork for effective mechano-therapeutic strategies for dentinal diseases.
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Affiliation(s)
- Xiangting Fu
- Institute of Tissue Regeneration Engineering (ITREN), Dankook University, Cheonan 31116, Republic of Korea;
- Mechanobiology Dental Medicine Research Center, Cheonan 31116, Republic of Korea
- Department of Nanobiomedical Science and BK21 NBM Global Research Center for Regenerative Medicine, Dankook University, Cheonan 31116, Republic of Korea
| | - Hye Sung Kim
- Institute of Tissue Regeneration Engineering (ITREN), Dankook University, Cheonan 31116, Republic of Korea;
- Mechanobiology Dental Medicine Research Center, Cheonan 31116, Republic of Korea
- Department of Nanobiomedical Science and BK21 NBM Global Research Center for Regenerative Medicine, Dankook University, Cheonan 31116, Republic of Korea
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2
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Tranter JD, Kumar A, Nair VK, Sah R. Mechanosensing in Metabolism. Compr Physiol 2023; 14:5269-5290. [PMID: 38158369 DOI: 10.1002/cphy.c230005] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2024]
Abstract
Electrical mechanosensing is a process mediated by specialized ion channels, gated directly or indirectly by mechanical forces, which allows cells to detect and subsequently respond to mechanical stimuli. The activation of mechanosensitive (MS) ion channels, intrinsically gated by mechanical forces, or mechanoresponsive (MR) ion channels, indirectly gated by mechanical forces, results in electrical signaling across lipid bilayers, such as the plasma membrane. While the functions of mechanically gated channels within a sensory context (e.g., proprioception and touch) are well described, there is emerging data demonstrating functions beyond touch and proprioception, including mechanoregulation of intracellular signaling and cellular/systemic metabolism. Both MR and MS ion channel signaling have been shown to contribute to the regulation of metabolic dysfunction, including obesity, insulin resistance, impaired insulin secretion, and inflammation. This review summarizes our current understanding of the contributions of several MS/MR ion channels in cell types implicated in metabolic dysfunction, namely, adipocytes, pancreatic β-cells, hepatocytes, and skeletal muscle cells, and discusses MS/MR ion channels as possible therapeutic targets. © 2024 American Physiological Society. Compr Physiol 14:5269-5290, 2024.
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Affiliation(s)
- John D Tranter
- Department of Internal Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Ashutosh Kumar
- Department of Internal Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Vinayak K Nair
- Department of Internal Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Rajan Sah
- Department of Internal Medicine, Cardiovascular Division, Washington University School of Medicine, St. Louis, Missouri, USA
- Center for Cardiovascular Research, Washington University, St. Louis, Missouri, USA
- St. Louis VA Medical Center, St. Louis, Missouri, USA
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3
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Sexually dimorphic architecture and function of a mechanosensory circuit in C. elegans. Nat Commun 2022; 13:6825. [PMID: 36369281 PMCID: PMC9652301 DOI: 10.1038/s41467-022-34661-3] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2022] [Accepted: 11/01/2022] [Indexed: 11/13/2022] Open
Abstract
How sensory perception is processed by the two sexes of an organism is still only partially understood. Despite some evidence for sexual dimorphism in auditory and olfactory perception, whether touch is sensed in a dimorphic manner has not been addressed. Here we find that the neuronal circuit for tail mechanosensation in C. elegans is wired differently in the two sexes and employs a different combination of sex-shared sensory neurons and interneurons in each sex. Reverse genetic screens uncovered cell- and sex-specific functions of the alpha-tubulin mec-12 and the sodium channel tmc-1 in sensory neurons, and of the glutamate receptors nmr-1 and glr-1 in interneurons, revealing the underlying molecular mechanisms that mediate tail mechanosensation. Moreover, we show that only in males, the sex-shared interneuron AVG is strongly activated by tail mechanical stimulation, and accordingly is crucial for their behavioral response. Importantly, sex reversal experiments demonstrate that the sexual identity of AVG determines both the behavioral output of the mechanosensory response and the molecular pathways controlling it. Our results present extensive sexual dimorphism in a mechanosensory circuit at both the cellular and molecular levels.
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Rong Y, Jiang J, Gao Y, Guo J, Song D, Liu W, Zhang M, Zhao Y, Xiao B, Liu Z. TMEM120A contains a specific coenzyme A-binding site and might not mediate poking- or stretch-induced channel activities in cells. eLife 2021; 10:e71474. [PMID: 34409941 PMCID: PMC8480983 DOI: 10.7554/elife.71474] [Citation(s) in RCA: 14] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2021] [Accepted: 08/16/2021] [Indexed: 01/03/2023] Open
Abstract
TMEM120A, a member of the transmembrane protein 120 (TMEM120) family, has a pivotal function in adipocyte differentiation and metabolism, and may also contribute to sensing mechanical pain by functioning as an ion channel named TACAN. Here we report that expression of TMEM120A is not sufficient in mediating poking- or stretch-induced currents in cells and have solved cryo-electron microscopy (cryo-EM) structures of human TMEM120A (HsTMEM120A) in complex with an endogenous metabolic cofactor (coenzyme A, CoASH) and in the apo form. HsTMEM120A forms a symmetrical homodimer with each monomer containing an amino-terminal coiled-coil motif followed by a transmembrane domain with six membrane-spanning helices. Within the transmembrane domain, a CoASH molecule is hosted in a deep cavity and forms specific interactions with nearby amino acid residues. Mutation of a central tryptophan residue involved in binding CoASH dramatically reduced the binding affinity of HsTMEM120A with CoASH. HsTMEM120A exhibits distinct conformations at the states with or without CoASH bound. Our results suggest that TMEM120A may have alternative functional roles potentially involved in CoASH transport, sensing, or metabolism.
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Affiliation(s)
- Yao Rong
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of SciencesBeijingChina
- College of Life Sciences, University of Chinese Academy of SciencesBeijingChina
| | - Jinghui Jiang
- State Key Laboratory of Membrane Biology; Tsinghua-Peking Center for Life Sciences; Beijing Advanced Innovation Center for Structural Biology; IDG/McGovern Institute for Brain Research; School of Pharmaceutical Sciences, Tsinghua UniversityBeijingChina
| | - Yiwei Gao
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of SciencesBeijingChina
- College of Life Sciences, University of Chinese Academy of SciencesBeijingChina
| | - Jianli Guo
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of SciencesBeijingChina
| | - Danfeng Song
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of SciencesBeijingChina
- College of Life Sciences, University of Chinese Academy of SciencesBeijingChina
| | - Wenhao Liu
- State Key Laboratory of Membrane Biology; Tsinghua-Peking Center for Life Sciences; Beijing Advanced Innovation Center for Structural Biology; IDG/McGovern Institute for Brain Research; School of Pharmaceutical Sciences, Tsinghua UniversityBeijingChina
| | - Mingmin Zhang
- State Key Laboratory of Membrane Biology; Tsinghua-Peking Center for Life Sciences; Beijing Advanced Innovation Center for Structural Biology; IDG/McGovern Institute for Brain Research; School of Pharmaceutical Sciences, Tsinghua UniversityBeijingChina
| | - Yan Zhao
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of SciencesBeijingChina
- College of Life Sciences, University of Chinese Academy of SciencesBeijingChina
- State Key Laboratory of Brain and Cognitive Science, Institute of Biophysics, Chinese Academy of SciencesBeijingChina
| | - Bailong Xiao
- State Key Laboratory of Membrane Biology; Tsinghua-Peking Center for Life Sciences; Beijing Advanced Innovation Center for Structural Biology; IDG/McGovern Institute for Brain Research; School of Pharmaceutical Sciences, Tsinghua UniversityBeijingChina
| | - Zhenfeng Liu
- National Laboratory of Biomacromolecules, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of SciencesBeijingChina
- College of Life Sciences, University of Chinese Academy of SciencesBeijingChina
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5
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Liu P, Lou X, Wingfield JL, Lin J, Nicastro D, Lechtreck K. Chlamydomonas PKD2 organizes mastigonemes, hair-like glycoprotein polymers on cilia. J Cell Biol 2021; 219:151720. [PMID: 32348466 PMCID: PMC7265326 DOI: 10.1083/jcb.202001122] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2020] [Revised: 03/10/2020] [Accepted: 03/16/2020] [Indexed: 12/20/2022] Open
Abstract
Mutations in the channel protein PKD2 cause autosomal dominant polycystic kidney disease, but the function of PKD2 in cilia remains unclear. Here, we show that PKD2 targets and anchors mastigonemes, filamentous polymers of the glycoprotein MST1, to the extracellular surface of Chlamydomonas cilia. PKD2–mastigoneme complexes physically connect to the axonemal doublets 4 and 8, positioning them perpendicular to the plane of ciliary beating. pkd2 mutant cilia lack mastigonemes, and mutant cells swim with reduced velocity, indicating a motility-related function of the PKD2–mastigoneme complex. Association with both the axoneme and extracellular structures supports a mechanosensory role of Chlamydomonas PKD2. We propose that PKD2–mastigoneme arrays, on opposing sides of the cilium, could perceive forces during ciliary beating and transfer these signals to locally regulate the response of the axoneme.
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Affiliation(s)
- Peiwei Liu
- Department of Cellular Biology, University of Georgia, Athens, GA
| | - Xiaochu Lou
- Departments of Cell Biology and Biophysics, University of Texas Southwestern Medical Center, Dallas, TX
| | | | - Jianfeng Lin
- Departments of Cell Biology and Biophysics, University of Texas Southwestern Medical Center, Dallas, TX
| | - Daniela Nicastro
- Departments of Cell Biology and Biophysics, University of Texas Southwestern Medical Center, Dallas, TX
| | - Karl Lechtreck
- Department of Cellular Biology, University of Georgia, Athens, GA
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6
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Li B, Li S, Yan Z. Axonemal Dynein DNAH5 is Required for Sound Sensation in Drosophila Larvae. Neurosci Bull 2021; 37:523-534. [PMID: 33570705 DOI: 10.1007/s12264-021-00631-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2020] [Accepted: 05/09/2020] [Indexed: 11/29/2022] Open
Abstract
Chordotonal neurons are responsible for sound sensation in Drosophila. However, little is known about how they respond to sound with high sensitivity. Using genetic labeling, we found one of the Drosophila axonemal dynein heavy chains, CG9492 (DNAH5), was specifically expressed in larval chordotonal neurons and showed a distribution restricted to proximal cilia. While DNAH5 mutation did not affect the cilium morphology or the trafficking of Inactive, a candidate auditory transduction channel, larvae with DNAH5 mutation had reduced startle responses to sound at low and medium intensities. Calcium imaging confirmed that DNAH5 functioned autonomously in chordotonal neurons for larval sound sensation. Furthermore, disrupting DNAH5 resulted in a decrease of spike firing responses to low-level sound in chordotonal neurons. Intriguingly, DNAH5 mutant larvae displayed an altered frequency tuning curve of the auditory organs. All together, our findings support a critical role of DNAH5 in tuning the frequency selectivity and the sound sensitivity of larval auditory neurons.
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Affiliation(s)
- Bingxue Li
- State Key Laboratory of Medical Neurobiology and Ministry of Education Frontiers Center for Brain Science, Department of Physiology and Biophysics, Institute of Brain Science, School of Life Sciences, Fudan University, Shanghai, 200438, China
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen, 518132, China
| | - Songling Li
- State Key Laboratory of Medical Neurobiology and Ministry of Education Frontiers Center for Brain Science, Department of Physiology and Biophysics, Institute of Brain Science, School of Life Sciences, Fudan University, Shanghai, 200438, China
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen, 518132, China
| | - Zhiqiang Yan
- State Key Laboratory of Medical Neurobiology and Ministry of Education Frontiers Center for Brain Science, Department of Physiology and Biophysics, Institute of Brain Science, School of Life Sciences, Fudan University, Shanghai, 200438, China.
- Institute of Molecular Physiology, Shenzhen Bay Laboratory, Shenzhen, 518132, China.
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7
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Baratchi S, Khoshmanesh K, Cox CD, Gomez GA. Editorial: Mechanobiology: Emerging Tools and Methods. Front Bioeng Biotechnol 2020; 8:289. [PMID: 32328482 PMCID: PMC7160851 DOI: 10.3389/fbioe.2020.00289] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2019] [Accepted: 03/19/2020] [Indexed: 11/13/2022] Open
Affiliation(s)
- Sara Baratchi
- School of Health and Biomedical Sciences, RMIT University, Bundoora, VIC, Australia
| | | | - Charles David Cox
- Molecular Cardiology and Biophysics Division, Victor Chang Cardiac Research Institute, Sydney, NSW, Australia
| | - Guillermo Alberto Gomez
- Centre for Cancer Biology, University of South Australia and SA Pathology, Adelaide, SA, Australia
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8
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Tanaka T, Takao-Kawabata R, Takakura A, Shimazu Y, Nakatsugawa M, Ito A, Lee JW, Kawasaki K, Iimura T. Teriparatide relieves ovariectomy-induced hyperalgesia in rats, suggesting the involvement of functional regulation in primary sensory neurons by PTH-mediated signaling. Sci Rep 2020; 10:5346. [PMID: 32210273 PMCID: PMC7093455 DOI: 10.1038/s41598-020-62045-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Accepted: 03/03/2020] [Indexed: 11/09/2022] Open
Abstract
Clinical studies have reported that teriparatide (TPTD), a human parathyroid hormone analog, reduces back pain in osteoporotic patients. However, the mechanistic insights of this pharmacological action remain elusive. This study investigated the antinociceptive effect of TPTD mainly on primary sensory neurons in ovariectomized (OVX) rats. The plantar test showed thermal hyperalgesia in the OVX rats, which was significantly, but not fully, recovered immediately after the initial TPTD administration. The von Frey test also demonstrated reduced withdrawal threshold in the OVX rats. This was partially recovered by TPTD. Consistently, the number and size of spinal microglial cells were significantly increased in the OVX rats, while TPTD treatment significantly reduced the number but not size of these cells. RNA sequencing-based bioinformatics of the dorsal root ganglia (DRG) demonstrated that changes in neuro-protective and inflammatory genes were involved in the pharmacological effect of TPTD. Most neurons in the DRG expressed substantial levels of parathyroid hormone 1 receptor. TPTD treatment of the cultured DRG-derived neuronal cells reduced the cAMP level and augmented the intracellular calcium level as the concentration increased. These findings suggest that TPTD targets neuronal cells as well as bone cells to exert its pharmacological action.
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Affiliation(s)
- Tomoya Tanaka
- Pharmaceuticals Research Center, Asahi Kasei Pharma Corporation, 632-1 Mifuku, Izunokuni city, Shizuoka, 410-2321, Japan.,Department of Pharmacology, Graduate School of Dental Medicine, Hokkaido University, N13 W7, Sapporo, 060-8586, Japan
| | - Ryoko Takao-Kawabata
- Pharmaceuticals Research Center, Asahi Kasei Pharma Corporation, 632-1 Mifuku, Izunokuni city, Shizuoka, 410-2321, Japan.
| | - Aya Takakura
- Pharmaceuticals Research Center, Asahi Kasei Pharma Corporation, 632-1 Mifuku, Izunokuni city, Shizuoka, 410-2321, Japan.,Department of Pharmacology, Graduate School of Dental Medicine, Hokkaido University, N13 W7, Sapporo, 060-8586, Japan
| | - Yukari Shimazu
- Pharmaceuticals Research Center, Asahi Kasei Pharma Corporation, 632-1 Mifuku, Izunokuni city, Shizuoka, 410-2321, Japan
| | - Momoko Nakatsugawa
- Pharmaceuticals Research Center, Asahi Kasei Pharma Corporation, 632-1 Mifuku, Izunokuni city, Shizuoka, 410-2321, Japan
| | - Akitoshi Ito
- Pharmaceuticals Research Center, Asahi Kasei Pharma Corporation, 632-1 Mifuku, Izunokuni city, Shizuoka, 410-2321, Japan
| | - Ji-Won Lee
- Department of Pharmacology, Graduate School of Dental Medicine, Hokkaido University, N13 W7, Sapporo, 060-8586, Japan.,Division of Bio-Imaging, Proteo-Science Center (PROS), Ehime University, Shitsukawa, Toon city, Ehime, 791-0295, Japan
| | - Koh Kawasaki
- Pharmaceuticals Research Center, Asahi Kasei Pharma Corporation, 632-1 Mifuku, Izunokuni city, Shizuoka, 410-2321, Japan
| | - Tadahiro Iimura
- Department of Pharmacology, Graduate School of Dental Medicine, Hokkaido University, N13 W7, Sapporo, 060-8586, Japan. .,Division of Bio-Imaging, Proteo-Science Center (PROS), Ehime University, Shitsukawa, Toon city, Ehime, 791-0295, Japan.
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9
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Startek JB, Boonen B, Talavera K, Meseguer V. TRP Channels as Sensors of Chemically-Induced Changes in Cell Membrane Mechanical Properties. Int J Mol Sci 2019; 20:E371. [PMID: 30654572 PMCID: PMC6359677 DOI: 10.3390/ijms20020371] [Citation(s) in RCA: 47] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2018] [Revised: 01/11/2019] [Accepted: 01/12/2019] [Indexed: 12/19/2022] Open
Abstract
Transient Receptor Potential ion channels (TRPs) have been described as polymodal sensors, being responsible for transducing a wide variety of stimuli, and being involved in sensory functions such as chemosensation, thermosensation, mechanosensation, and photosensation. Mechanical and chemical stresses exerted on the membrane can be transduced by specialized proteins into meaningful intracellular biochemical signaling, resulting in physiological changes. Of particular interest are compounds that can change the local physical properties of the membrane, thereby affecting nearby proteins, such as TRP channels, which are highly sensitive to the membrane environment. In this review, we provide an overview of the current knowledge of TRP channel activation as a result of changes in the membrane properties induced by amphipathic structural lipidic components such as cholesterol and diacylglycerol, and by exogenous amphipathic bacterial endotoxins.
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Affiliation(s)
- Justyna B Startek
- Laboratory of Ion Channel Research, Department of Cellular and Molecular Medicine, KU Leuven; VIB Center for Brain & Disease Research, Herestraat 49, Campus Gasthuisberg O&N1 bus 802, 3000 Leuven, Belgium.
| | - Brett Boonen
- Laboratory of Ion Channel Research, Department of Cellular and Molecular Medicine, KU Leuven; VIB Center for Brain & Disease Research, Herestraat 49, Campus Gasthuisberg O&N1 bus 802, 3000 Leuven, Belgium.
| | - Karel Talavera
- Laboratory of Ion Channel Research, Department of Cellular and Molecular Medicine, KU Leuven; VIB Center for Brain & Disease Research, Herestraat 49, Campus Gasthuisberg O&N1 bus 802, 3000 Leuven, Belgium.
| | - Victor Meseguer
- Instituto de Neurociencias de Alicante, Universidad Miguel Hernández y CSIC, E-03550 Alicante , Spain.
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Dohke T, Iba K, Hanaka M, Kanaya K, Okazaki S, Yamashita T. Teriparatide rapidly improves pain-like behavior in ovariectomized mice in association with the downregulation of inflammatory cytokine expression. J Bone Miner Metab 2018; 36:499-507. [PMID: 28983699 DOI: 10.1007/s00774-017-0865-0] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/25/2017] [Accepted: 08/20/2017] [Indexed: 12/18/2022]
Abstract
Recent studies have indicated that teriparatide, an anti-osteoporosis agent, significantly improves back pain regardless of the presence of vertebral fracture in osteoporosis patients. The aims of this study were to examine whether teriparatide improves pain-like behavior in an ovariectomized (OVX) mouse model, and to evaluate changes in osteoclast marker levels and inflammatory cytokine expression levels induced by teriparatide treatment in bone tissue in association with improvements in pain-like behavior. OVX and sham operations were performed in 8-week-old mice, followed by teriparatide treatment for 2 weeks. Pain-like behavior tests (von Frey, paw flick and spontaneous pain test), and the measurement of serum tartrate-resistant acid phosphatase 5b (TRAP5b) level and inflammatory cytokine (interleukin [IL]-1β, IL-6 and tumor necrosis factor [TNF]-α) expression levels in the bone tissue were conducted after teriparatide treatment in OVX mice. Pain-like behavior in the von Frey test was significantly improved by teriparatide treatment in OVX mice. With regard to the early phase (within the first 7 days of treatment), teriparatide significantly improved pain-like behavior in the von Frey test, the paw flick test and the spontaneous pain test. Teriparatide significantly inhibited the expression of IL-1β, IL-6 and TNF-α in OVX mice in the early phase of the treatment, while the TRAP5b level in OVX mice was not significantly affected. We demonstrated that the teriparatide-induced rapid improvement effect on pain-like behavior in OVX mice was associated with the downregulation of inflammatory cytokine expression, including IL-1β, IL-6 and TNF-α.
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Affiliation(s)
- Takayuki Dohke
- Department of Orthopaedic Surgery, Sapporo Medical University School of Medicine, Sapporo, Japan
| | - Kousuke Iba
- Department of Orthopaedic Surgery, Sapporo Medical University School of Medicine, Sapporo, Japan.
| | - Megumi Hanaka
- Department of Orthopaedic Surgery, Sapporo Medical University School of Medicine, Sapporo, Japan
| | - Kumiko Kanaya
- Department of Orthopaedic Surgery, Sapporo Medical University School of Medicine, Sapporo, Japan
| | - Shunichiro Okazaki
- Department of Orthopaedic Surgery, Sapporo Medical University School of Medicine, Sapporo, Japan
| | - Toshihiko Yamashita
- Department of Orthopaedic Surgery, Sapporo Medical University School of Medicine, Sapporo, Japan
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11
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de Oliveira RF, Goldman RS, Mendes FM, de Freitas PM. Influence of Electroacupuncture and Laser-Acupuncture on Treating Paresthesia in Patients Submitted to Combined Orthognathic Surgery and Genioplasty. Med Acupunct 2017; 29:290-299. [PMID: 29067139 DOI: 10.1089/acu.2017.1228] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Objective: The goal of this research was to observe the influence of electroacupuncture (EA) and laser-acupuncture on the return of tactile/pain sensitivity in patients who underwent orthognathic surgery. Materials and Methods: Thirty volunteers subjected to orthognathic surgery were evaluated and randomly divided into 2 groups, in which 3 treatments were evaluated: control (n = 30) (G0, medication + placebo laser treatment) and 2 experimental treatments (n = 15) (G1, medication + EA) or G2 (medication + laser-acupuncture). The control group had n = 30 because for each experimental treatment conducted on a volunteer's hemi-face, there was a control treatment on the other hemi-face. In G1, medication was given with EA, with needles placed at predetermined points (ST 4 [Dicang], M-HN-18 [Jiachengjiang], CV 24 [Chengjiang], ST 5 [Daying], ST 6 [Jiache], and point A1 [YNSA]). For electrostimulation, the device used delivered transcutaneous electrical nerve stimulation of a burst type, with intensity and frequency variations of T = 220 ms and F = 4 Hz (30 minutes, 2 × /week). In G2, in addition to the medication, laser irradiation (at 780 nm) was applied on acupuncture points (at 0.04 cm2, 70 mW, 6 s/point, 0.42 J/point, 10 J/cm2, 2 × /week). All volunteers were evaluated before and during the 4 months following the surgery. Tactile sensitivity was assessed by mechanical brushing (brush #s 2 and 12) and by a 2-point discrimination test, using a bow compass. A pain test was performed with a pulp electrical test that stimulates intact nerves of the dentin-pulp complex. A Kaplan-Meier test was performed, and survival curves were plotted for comparison between groups. Cox regression analysis was also conducted (α = 0.05). Results: There were no statistically significant differences among the groups for the 2-point discrimination test (brushes #2 and #12) on the buccal mucosa region and for the pulp test on all evaluated regions. However, the tactile test using brush #12 revealed significant differences between G1 and the other groups when considering the lower lip (P = 0.024) and chin (P = 0.028) areas. Conclusions: Only EA was able to influence-using the brushing test (brush #12)-the return of tactile sensitivity on the chin and lower lip positively after combined orthognathic surgery and genioplasty.
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Affiliation(s)
- Renata F de Oliveira
- Special Laboratory of Lasers in Dentistry, Department of Restorative Dentistry, School of Dentistry, University of São Paulo, São Paulo, SP, Brazil
| | - Ricardo S Goldman
- Clínica de Cirurgia e Traumatologia Buco-Maxilo-Faciais, São Paulo, SP, Brazil
| | - Fausto Medeiros Mendes
- Department of Orthodontics and Pediatrics Dentistry, School of Dentistry, University of São Paulo, São Paulo, SP, Brazil
| | - Patricia Moreira de Freitas
- Special Laboratory of Lasers in Dentistry, Department of Restorative Dentistry, School of Dentistry, University of São Paulo, São Paulo, SP, Brazil
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12
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Abstract
Mechanosensitive ion channels initiate sensory signals by converting mechanical information into electrochemical signals. In this issue of Neuron (Zhao et al., 2016), a data-rich structure-function study on mammalian mechanosensitive Piezo channels reveals a modular protein architecture that includes a central pore module surrounded by a force-sensing module.
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Affiliation(s)
- Nurunisa Akyuz
- Department of Neurobiology and Howard Hughes Medical Institute, Harvard Medical School, Boston, MA 02115, USA
| | - Jeffrey R Holt
- Department of Otolaryngology, F.M. Kirby Neurobiology Center, Boston Children's Hospital, Harvard Medical School, Boston, MA 02115, USA.
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13
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Abstract
Mechanoelectrical transduction of acoustic signals is the fundamental process for hearing in all ears across the animal kingdom. Here, we performed in vivo laser-vibrometric and electrophysiological measurements at the transduction site in an insect ear (Mecopoda elongata) to relate the biomechanical tonotopy along the hearing organ to the frequency tuning of the corresponding sensory cells. Our mechanical and electrophysiological map revealed a biomechanical filter process that considerably sharpens the neuronal response. We demonstrate that the channel gating, which acts on chordotonal stretch receptor neurons, is based on a mechanical directionality of the sound-induced motion. Further, anatomical studies of the transduction site support our finding of a stimulus-relevant tilt. In conclusion, we were able to show, in an insect ear, that directionality of channel gating considerably sharpens the neuronal frequency selectivity at the peripheral level and have identified a mechanism that enhances frequency discrimination in tonotopically organized ears.
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14
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Kanaya K, Iba K, Abe Y, Dohke T, Okazaki S, Matsumura T, Yamashita T. Acid-sensing ion channel 3 or P2X2/3 is involved in the pain-like behavior under a high bone turnover state in ovariectomized mice. J Orthop Res 2016; 34:566-73. [PMID: 26340235 DOI: 10.1002/jor.23047] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 08/28/2015] [Indexed: 02/04/2023]
Abstract
We have recently demonstrated that pathological changes leading to increased bone resorption by osteoclast activation are related to the induction of pain-like behavior in ovariectomized (OVX) mice. In addition, bisphosphonate and the antagonist of transient receptor potential vanilloid type 1 (TRPV1), an acid-sensing nociceptor, improved the threshold value of pain-like behaviors accompanying an improvement in the acidic environment in the bone tissue based on osteoclast inactivation. The aim of this study was to evaluate the effect of (i) an inhibitor of vacuolar H(+) -ATPase, known as an proton pump, (ii) an antagonist of acid-sensing ion channel (ASIC) 3, as another acid-sensing nociceptor, and (iii) the P2X2/3 receptor, as an ATP-ligand nociceptor, on pain-like behavior in OVX mice. This inhibitor and antagonists were found to improve the threshold value of pain-like behavior in OVX mice. These results indicated that the skeletal pain accompanying osteoporosis is possibly associated with the acidic microenvironment and increased ATP level caused by osteoclast activation under a high bone turnover state.
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Affiliation(s)
- Kumiko Kanaya
- Department of Orthopaedic Surgery, Sapporo Medical University School of Medicine, Sapporo, Japan
| | - Kousuke Iba
- Department of Orthopaedic Surgery, Sapporo Medical University School of Medicine, Sapporo, Japan
| | - Yasuhisa Abe
- Department of Orthopaedic Surgery, Sapporo Medical University School of Medicine, Sapporo, Japan
| | - Takayuki Dohke
- Department of Orthopaedic Surgery, Sapporo Medical University School of Medicine, Sapporo, Japan
| | - Shunichiro Okazaki
- Department of Orthopaedic Surgery, Sapporo Medical University School of Medicine, Sapporo, Japan
| | - Tadaki Matsumura
- Department of Orthopaedic Surgery, Sapporo Medical University School of Medicine, Sapporo, Japan
| | - Toshihiko Yamashita
- Department of Orthopaedic Surgery, Sapporo Medical University School of Medicine, Sapporo, Japan
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15
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Kachalo S, Naveed H, Cao Y, Zhao J, Liang J. Mechanical model of geometric cell and topological algorithm for cell dynamics from single-cell to formation of monolayered tissues with pattern. PLoS One 2015; 10:e0126484. [PMID: 25974182 PMCID: PMC4431879 DOI: 10.1371/journal.pone.0126484] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2014] [Accepted: 04/02/2015] [Indexed: 11/19/2022] Open
Abstract
Geometric and mechanical properties of individual cells and interactions among neighboring cells are the basis of formation of tissue patterns. Understanding the complex interplay of cells is essential for gaining insight into embryogenesis, tissue development, and other emerging behavior. Here we describe a cell model and an efficient geometric algorithm for studying the dynamic process of tissue formation in 2D (e.g. epithelial tissues). Our approach improves upon previous methods by incorporating properties of individual cells as well as detailed description of the dynamic growth process, with all topological changes accounted for. Cell size, shape, and division plane orientation are modeled realistically. In addition, cell birth, cell growth, cell shrinkage, cell death, cell division, cell collision, and cell rearrangements are now fully accounted for. Different models of cell-cell interactions, such as lateral inhibition during the process of growth, can be studied in detail. Cellular pattern formation for monolayered tissues from arbitrary initial conditions, including that of a single cell, can also be studied in detail. Computational efficiency is achieved through the employment of a special data structure that ensures access to neighboring cells in constant time, without additional space requirement. We have successfully generated tissues consisting of more than 20,000 cells starting from 2 cells within 1 hour. We show that our model can be used to study embryogenesis, tissue fusion, and cell apoptosis. We give detailed study of the classical developmental process of bristle formation on the epidermis of D. melanogaster and the fundamental problem of homeostatic size control in epithelial tissues. Simulation results reveal significant roles of solubility of secreted factors in both the bristle formation and the homeostatic control of tissue size. Our method can be used to study broad problems in monolayered tissue formation. Our software is publicly available.
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Affiliation(s)
- Sëma Kachalo
- Department of Bioengineering, The University of Illinois at Chicago, Chicago, IL, 60607
| | - Hammad Naveed
- Department of Bioengineering, The University of Illinois at Chicago, Chicago, IL, 60607
- Computer, Electrical and Mathematical Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal, Saudi Arabia
| | - Youfang Cao
- Department of Bioengineering, The University of Illinois at Chicago, Chicago, IL, 60607
| | - Jieling Zhao
- Department of Bioengineering, The University of Illinois at Chicago, Chicago, IL, 60607
| | - Jie Liang
- Department of Bioengineering, The University of Illinois at Chicago, Chicago, IL, 60607
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16
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Meng Q, Fang P, Hu Z, Ling Y, Liu H. Mechanotransduction of trigeminal ganglion neurons innervating inner walls of rat anterior eye chambers. Am J Physiol Cell Physiol 2015; 309:C1-10. [PMID: 25904679 DOI: 10.1152/ajpcell.00028.2015] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/02/2015] [Accepted: 04/20/2015] [Indexed: 11/22/2022]
Abstract
To address mechanoreceptive roles of trigeminal ganglion (TG) nerve endings in the inner walls of rat anterior eye chambers, we investigated the mechanotransduction process and mechanosensitive (MS) channel on somata of TG neurons innervating this area in vitro. Rat TG neurons innervating inner walls of anterior chambers were labeled by anterior chamber injection of 1,1'-dilinoleyl-3,3,3',3'-tetramethylindocarbocyanine, 4-chlorobenzenesulfonate (FAST DiI). The neuronal cell bodies were voltage clamped using a whole cell patch-clamp technique, while it was deformed by ejection of bath solution to verify mechanotransduction. Immunofluorescence staining was performed on sections of TG ganglia to determine the specific MS channel proteins. Mechanical stimuli induced MS currents in 55 out of 96 FAST DiI-labeled TG neurons. The MS currents exhibited mechanical intensity-dependent and clamp voltage-dependent characteristics. Mechanical stimulation further enhanced the membrane potential and increased the frequency of action potentials. Transient receptor potential ankyrin 1 (TRPA1), TRP vanilloid 4 (TRPV4), acid-sensing ion channel (ASIC) 2 and ASIC3 channel proteins were expressed in FAST DiI-labeled TG neurons. The inhibitory effect of HC-030031, a specific inhibitor of TRPA1, on MS currents demonstrated that TRPA1 was an essential MS channel protein. Taken together, our results show that mechanical stimuli induce MS currents via MS channels such as TRPA1 to trigger mechanotransduction in TG neurons innervating inner walls of anterior chambers. Our results indicate the existence of mechanoreceptive TG nerve endings in inner walls of anterior chambers. Whether the mechanoreceptive TG nerve endings play a role in intraocular pressure sensation warrants further investigation.
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Affiliation(s)
- Qingli Meng
- Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Hubei, China; and
| | - Peng Fang
- Department of Pharmacology, Tongji Medical College, Huazhong University of Science and Technology, Hubei, China
| | - Zhuangli Hu
- Department of Pharmacology, Tongji Medical College, Huazhong University of Science and Technology, Hubei, China
| | - Yun Ling
- Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Hubei, China; and
| | - Haixia Liu
- Department of Ophthalmology, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Hubei, China; and
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17
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Peyronnet R, Sharif-Naeini R, Folgering JHA, Arhatte M, Jodar M, El Boustany C, Gallian C, Tauc M, Duranton C, Rubera I, Lesage F, Pei Y, Peters DJM, Somlo S, Sachs F, Patel A, Honoré E, Duprat F. Mechanoprotection by polycystins against apoptosis is mediated through the opening of stretch-activated K(2P) channels. Cell Rep 2012; 1:241-50. [PMID: 22832196 DOI: 10.1016/j.celrep.2012.01.006] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Revised: 12/27/2011] [Accepted: 01/30/2012] [Indexed: 12/31/2022] Open
Abstract
How renal epithelial cells respond to increased pressure and the link with kidney disease states remain poorly understood. Pkd1 knockout or expression of a PC2 pathogenic mutant, mimicking the autosomal dominant polycystic kidney disease, dramatically enhances mechanical stress-induced tubular apoptotic cell death. We show the presence of a stretch-activated K(+) channel dependent on the TREK-2 K(2P) subunit in proximal convoluted tubule epithelial cells. Our findings further demonstrate that polycystins protect renal epithelial cells against apoptosis in response to mechanical stress, and this function is mediated through the opening of stretch-activated K(2P) channels. Thus, to our knowledge, we establish for the first time, both in vitro and in vivo, a functional relationship between mechanotransduction and mechanoprotection. We propose that this mechanism is at play in other important pathologies associated with apoptosis and in which pressure or flow stimulation is altered, including heart failure or atherosclerosis.
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Affiliation(s)
- Rémi Peyronnet
- Institut de Pharmacologie Moléculaire et Cellulaire, UMR CNRS 7275, Université de Nice Sophia Antipolis, 06560 Valbonne, France
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18
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Laminar shear stress modulates the activity of heterologously expressed P2X(4) receptors. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2011; 1808:2488-95. [PMID: 21798232 DOI: 10.1016/j.bbamem.2011.07.010] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2011] [Revised: 06/24/2011] [Accepted: 07/12/2011] [Indexed: 12/20/2022]
Abstract
P2X(4) receptors are involved in mechanotransduction processes, but it is unknown whether or not P2X(4) receptors form mechanosensitive ion channels. This study questioned, whether laminar shear stress (LSS) can modulate P2X(4) receptor activity. Mouse P2X(4) receptor was cloned and heterologously expressed in Xenopus laevis oocytes. In two-electrode-voltage-clamp experiments the application of ATP (100μM) produced a transient inward current that was decreased by about 50% upon a second ATP application, corresponding to the desensitization behavior of P2X(4) receptors. In P2X(4) expressing oocytes LSS (shear forces of ~5.1dynes/cm(2)) did not produce any effect. However, LSS modulated the response of P2X(4) to ATP. With LSS (~5.1dynes/cm(2)) the desensitization of the current due to the second ATP application was diminished. Ivermectin (IVM), a compound which stabilizes the open state of P2X(4) receptors, mimicked the effect of LSS (~5.1dynes/cm(2)), since there was no additional effect of LSS after pre-incubation with IVM detected. This indicates that LSS like IVM stabilizes the open state of the receptor, although the particular mechanism remains unknown. These data demonstrate that LSS modulates the activity of P2X(4) receptors by eliminating the desensitization of the receptors in response to ATP probably by stabilizing the open state of the channel.
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19
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Chatzigeorgiou M, Schafer W. Lateral facilitation between primary mechanosensory neurons controls nose touch perception in C. elegans. Neuron 2011; 70:299-309. [PMID: 21521615 PMCID: PMC3145979 DOI: 10.1016/j.neuron.2011.02.046] [Citation(s) in RCA: 62] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/16/2011] [Indexed: 11/25/2022]
Abstract
The nematode C. elegans senses head and nose touch using multiple classes of mechanoreceptor neurons that are electrically coupled through a network of gap junctions. Using in vivo neuroimaging, we have found that multidendritic nociceptors in the head respond to harsh touch throughout their receptive field but respond to gentle touch only at the tip of the nose. Whereas the harsh touch response depends solely on cell-autonomous mechanosensory channels, gentle nose touch responses require facilitation by additional nose touch mechanoreceptors, which couple electrically to the nociceptors in a hub-and-spoke gap junction network. Conversely, nociceptor activity indirectly facilitates activation of the nose touch neurons, demonstrating that information flow across the network is bidirectional. Thus, a simple gap-junction circuit acts as a coincidence detector that allows primary sensory neurons to integrate information from neighboring mechanoreceptors and generate somatosensory perception.
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Affiliation(s)
- Marios Chatzigeorgiou
- Cell Biology Division, MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK
| | - William R. Schafer
- Cell Biology Division, MRC Laboratory of Molecular Biology, Hills Road, Cambridge CB2 2QH, UK
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20
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Dubin AE, Patapoutian A. Nociceptors: the sensors of the pain pathway. J Clin Invest 2010; 120:3760-72. [PMID: 21041958 DOI: 10.1172/jci42843] [Citation(s) in RCA: 695] [Impact Index Per Article: 49.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
Specialized peripheral sensory neurons known as nociceptors alert us to potentially damaging stimuli at the skin by detecting extremes in temperature and pressure and injury-related chemicals, and transducing these stimuli into long-ranging electrical signals that are relayed to higher brain centers. The activation of functionally distinct cutaneous nociceptor populations and the processing of information they convey provide a rich diversity of pain qualities. Current work in this field is providing researchers with a more thorough understanding of nociceptor cell biology at molecular and systems levels and insight that will allow the targeted design of novel pain therapeutics.
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Affiliation(s)
- Adrienne E Dubin
- Department of Cell Biology, The Scripps Research Institute, La Jolla, California, USA.
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21
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Chatzigeorgiou M, Grundy L, Kindt KS, Lee WH, Driscoll M, Schafer WR. Spatial asymmetry in the mechanosensory phenotypes of the C. elegans DEG/ENaC gene mec-10. J Neurophysiol 2010; 104:3334-44. [PMID: 20881202 DOI: 10.1152/jn.00330.2010] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
DEG/ENaC channels have been broadly implicated in mechanosensory transduction, yet many questions remain about how these proteins contribute to complexes that sense mechanical stimuli. In C. elegans, two DEG/ENaC channel subunits are thought to contribute to a gentle touch transduction complex: MEC-4, which is essential for gentle touch sensation, and MEC-10, whose importance is less well defined. By characterizing a mec-10 deletion mutant, we have found that MEC-10 is important, but not essential, for gentle touch responses in the body touch neurons ALM, PLM, and PVM. Surprisingly, the requirement for MEC-10 in ALM and PLM is spatially asymmetric; mec-10 animals show significant behavioral and physiological responses to stimulation at the distal end of touch neuron dendrites, but respond poorly to stimuli applied near the neuronal cell body. The subcellular distribution of a rescuing MEC-10::GFP translational fusion was found to be restricted to the neuronal cell body and proximal dendrite, consistent with the hypothesis that MEC-10 protein is asymmetrically distributed within the touch neuron process. These results suggest that MEC-10 may contribute to only a subset of gentle touch mechanosensory complexes found preferentially at the proximal dendrite.
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Affiliation(s)
- Marios Chatzigeorgiou
- Cell Biology Division, MRC Laboratory of Molecular Biology, Hills Road, Cambridge, CB2 2QH, UK
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22
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Specific roles for DEG/ENaC and TRP channels in touch and thermosensation in C. elegans nociceptors. Nat Neurosci 2010; 13:861-8. [PMID: 20512132 PMCID: PMC2975101 DOI: 10.1038/nn.2581] [Citation(s) in RCA: 177] [Impact Index Per Article: 12.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2010] [Accepted: 05/17/2010] [Indexed: 11/09/2022]
Abstract
Polymodal nociceptors detect noxious stimuli including harsh touch, toxic chemicals, and extremes of heat and cold. The molecular mechanisms by which nociceptors are able to sense multiple qualitatively distinct stimuli are not well-understood. We show here that the C. elegans PVD neurons are mulitidendritic nociceptors that respond to harsh touch as well as cold temperatures. The harsh touch modality specifically requires the DEG/ENaC proteins MEC-10 and DEGT-1, which represent putative components of a harsh touch mechanotransduction complex. By contrast, responses to cold require the TRPA-1 channel and are MEC-10- and DEGT-1-independent. Heterologous expression of C. elegans TRPA-1 can confer cold responsiveness to other C. elegans neurons or to mammalian cells, indicating that TRPA-1 is itself a cold sensor. These results show that C. elegans nociceptors respond to thermal and mechanical stimuli using distinct sets of molecules, and identify DEG/ENaC channels as potential receptors for mechanical pain.
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23
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Hibino H, Inanobe A, Furutani K, Murakami S, Findlay I, Kurachi Y. Inwardly rectifying potassium channels: their structure, function, and physiological roles. Physiol Rev 2010; 90:291-366. [PMID: 20086079 DOI: 10.1152/physrev.00021.2009] [Citation(s) in RCA: 1074] [Impact Index Per Article: 76.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Inwardly rectifying K(+) (Kir) channels allow K(+) to move more easily into rather than out of the cell. They have diverse physiological functions depending on their type and their location. There are seven Kir channel subfamilies that can be classified into four functional groups: classical Kir channels (Kir2.x) are constitutively active, G protein-gated Kir channels (Kir3.x) are regulated by G protein-coupled receptors, ATP-sensitive K(+) channels (Kir6.x) are tightly linked to cellular metabolism, and K(+) transport channels (Kir1.x, Kir4.x, Kir5.x, and Kir7.x). Inward rectification results from pore block by intracellular substances such as Mg(2+) and polyamines. Kir channel activity can be modulated by ions, phospholipids, and binding proteins. The basic building block of a Kir channel is made up of two transmembrane helices with cytoplasmic NH(2) and COOH termini and an extracellular loop which folds back to form the pore-lining ion selectivity filter. In vivo, functional Kir channels are composed of four such subunits which are either homo- or heterotetramers. Gene targeting and genetic analysis have linked Kir channel dysfunction to diverse pathologies. The crystal structure of different Kir channels is opening the way to understanding the structure-function relationships of this simple but diverse ion channel family.
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Affiliation(s)
- Hiroshi Hibino
- Department of Pharmacology, Graduate School of Medicine and The Center for Advanced Medical Engineering and Informatics, Osaka University, Osaka 565-0871, Japan
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24
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Tan PL, Katsanis N. Thermosensory and mechanosensory perception in human genetic disease. Hum Mol Genet 2009; 18:R146-55. [PMID: 19808790 DOI: 10.1093/hmg/ddp412] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/07/2023] Open
Abstract
Peripheral sensory perception is established through an elaborate network of specialized neurons that mediate the translation of extraorganismal stimuli through the use of a broad array of receptors and downstream effector molecules. Studies of human genetic disorders, as well as mouse and other animal models, have identified some of the key molecules necessary for peripheral innervation and function. These findings have, in turn, yielded new insights into the developmental networks and homeostatic mechanisms necessary for the transformation of external stimuli into interpretable electrical impulses. In this review, we will summarize and discuss some of the genes/proteins implicated in two particular aspects of sensory perception, thermosensation and mechanosensation, highlighting pathways whose perturbation leads to both isolated and syndromic sensory deficits.
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Affiliation(s)
- Perciliz L Tan
- McKusick-Nathans Institute of Genetic Medicine, Johns Hopkins University School of Medicine, Baltimore, MD 21205, USA
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25
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Simon A, Shenton F, Hunter I, Banks RW, Bewick GS. Amiloride-sensitive channels are a major contributor to mechanotransduction in mammalian muscle spindles. J Physiol 2009; 588:171-85. [PMID: 19917568 DOI: 10.1113/jphysiol.2009.182683] [Citation(s) in RCA: 72] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023] Open
Abstract
We investigated whether channels of the epithelial sodium/amiloride-sensitive degenerin (ENaC/DEG) family are a major contributor to mechanosensory transduction in primary mechanosensory afferents, using adult rat muscle spindles as a model system. Stretch-evoked afferent discharge was reduced in a dose-dependent manner by amiloride and three analogues - benzamil, 5-(N-ethyl-N-isopropyl) amiloride (EIPA) and hexamethyleneamiloride (HMA), reaching > or = 85% inhibition at 1 mm. Moreover, firing was slightly but significantly increased by ENaC delta subunit agonists (icilin and capsazepine). HMA's profile of effects was distinct from that of the other drugs. Amiloride, benzamil and EIPA significantly decreased firing (P < 0.01 each) at 1 microm, while 10 microm HMA was required for highly significant inhibition (P < 0.0001). Conversely, amiloride, benzamil and EIPA rarely blocked firing entirely at 1 mm, whereas 1 mm HMA blocked 12 of 16 preparations. This pharmacology suggests low-affinity ENaCs are the important spindle mechanotransducer. In agreement with this, immunoreactivity to ENaC alpha, beta and gamma subunits was detected both by Western blot and immunocytochemistry. Immunofluorescence intensity ratios for ENaC alpha, beta or gamma relative to the vesicle marker synaptophysin in the same spindle all significantly exceeded controls (P < 0.001). Ratios for the related brain sodium channel ASIC2 (BNaC1alpha) were also highly significantly greater (P < 0.005). Analysis of confocal images showed strong colocalisation within the terminal of ENaC/ASIC2 subunits and synaptophysin. This study implicates ENaC and ASIC2 in mammalian mechanotransduction. Moreover, within the terminals they colocalise with synaptophysin, a marker for the synaptic-like vesicles which regulate afferent excitability in these mechanosensitive endings.
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Affiliation(s)
- Anna Simon
- School of Medical Sciences, Institute of Medical Sciences, University of Aberdeen, Foresterhill, Aberdeen AB25 2ZD, UK.
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26
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Jernigan NL, Paffett ML, Walker BR, Resta TC. ASIC1 contributes to pulmonary vascular smooth muscle store-operated Ca(2+) entry. Am J Physiol Lung Cell Mol Physiol 2009; 297:L271-85. [PMID: 19482897 DOI: 10.1152/ajplung.00020.2009] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Acid-sensing ion channels (ASIC) are voltage-insensitive, cationic channels that have recently been identified in vascular smooth muscle (VSM). It is possible that ASIC contribute to vascular reactivity via Na(+) and Ca(2+) conductance; however, their function in VSM is largely unknown. In pulmonary VSM, store-operated Ca(2+) entry (SOCE) plays a significant role in vasoregulatory mechanisms such as hypoxic pulmonary vasoconstriction and receptor-mediated arterial constriction. Therefore, we hypothesized that ASIC contribute to SOCE in pulmonary VSM. We examined SOCE resulting from depletion of intracellular Ca(2+) stores with cyclopiazonic acid in isolated small pulmonary arteries and primary cultured pulmonary arterial smooth muscle cells by measuring 1) changes in VSM [Ca(2+)](i) using fura-2 indicator dye, 2) Mn(2+) quenching of fura-2 fluorescence, and 3) store-operated Ca(2+) and Na(+) currents using conventional whole cell patch-clamp configuration in voltage-clamp mode. The role of ASIC was assessed by the use of the ASIC inhibitors, amiloride, benzamil, and psalmotoxin 1, or siRNA directed towards ASIC1, ASIC2, or ASIC3 isoforms. We found that store-operated VSM [Ca(2+)](i) responses, Mn(2+) influx, and inward cationic currents were attenuated by either pharmacological ASIC inhibition or treatment with ASIC1 siRNA. These data establish a unique role for ASIC1 in mediating SOCE in pulmonary VSM and provide new insight into mechanisms of VSM Ca(2+) entry and pulmonary vasoregulation.
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Affiliation(s)
- Nikki L Jernigan
- Dept. of Cell Biology and Physiology, Univ. of New Mexico Health Sciences Center, Albuquerque, 87131-0001, USA.
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27
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Radial stretch reveals distinct populations of mechanosensitive mammalian somatosensory neurons. Proc Natl Acad Sci U S A 2008; 105:20015-20. [PMID: 19060212 DOI: 10.1073/pnas.0810801105] [Citation(s) in RCA: 69] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Primary afferent somatosensory neurons mediate our sense of touch in response to changes in ambient pressure. Molecules that detect and transduce thermal stimuli have been recently identified, but mechanisms underlying mechanosensation, particularly in vertebrate organisms, remain enigmatic. Traditionally, mechanically evoked responses in somatosensory neurons have been assessed one cell at a time by recording membrane currents in response to application of focal pressure, suction, or osmotic challenge. Here, we used radial stretch in combination with live-cell calcium imaging to gain a broad overview of mechanosensitive neuronal subpopulations. We found that different stretch intensities activate distinct subsets of sensory neurons as defined by size, molecular markers, or pharmacological attributes. In all subsets, stretch-evoked responses required extracellular calcium, indicating that mechanical force triggers calcium influx. This approach extends the repertoire of stimulus paradigms that can be used to examine mechanotransduction in mammalian sensory neurons, facilitating future physiological and pharmacological studies.
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28
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Lawson JJ, McIlwrath SL, Woodbury CJ, Davis BM, Koerber HR. TRPV1 unlike TRPV2 is restricted to a subset of mechanically insensitive cutaneous nociceptors responding to heat. THE JOURNAL OF PAIN 2008; 9:298-308. [PMID: 18226966 PMCID: PMC2372162 DOI: 10.1016/j.jpain.2007.12.001] [Citation(s) in RCA: 127] [Impact Index Per Article: 7.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/11/2007] [Revised: 12/04/2007] [Accepted: 12/04/2007] [Indexed: 01/12/2023]
Abstract
UNLABELLED In the present study, a murine ex vivo somatosensory system preparation was used to determine the response characteristics of cutaneous sensory neurons staining positively for TRPV1 or TRPV2. TRPV1 immunostaining was found exclusively (11/11) in a specific set of mechanically insensitive unmyelinated (C) nociceptors that responded to heating of their receptive fields. No cutaneous C-fibers that responded to both mechanical and heat stimuli stained positively for TRPV1 (0/62). The relationship between TRPV2 and heat transduction characteristics was not as clear, as few unmyelinated or myelinated fibers that responded to heat contained TRPV2. TRPV2 was found most frequently in mechanically sensitive myelinated fibers, including both low threshold and high threshold mechanoreceptors (nociceptors). Although TRPV2 was found in only 1 of 6 myelinated polymodal nociceptors, it was found in a majority (10/16) of myelinated mechanical nociceptors. Thus, whereas the in vivo role of TRPV1 as a heat-sensitive channel in cutaneous sensory neurons is clearly defined, the role of TRPV2 in cutaneous neurons remains unknown. These results also suggest that TRPV1 may be essential for heat transduction in a specific subset of mechanically insensitive cutaneous nociceptors and that this subset may constitute a discrete heat input pathway for inflammation-induced thermal pain. PERSPECTIVE The distinct subset of murine cutaneous nociceptors containing TRPV1 has many attributes in common with mechanically insensitive C-fibers in humans that are believed to play a role in pathological pain states. Therefore, these murine fibers provide a clinically relevant animal model for further study of this group of cutaneous nociceptors.
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MESH Headings
- Animals
- Calcitonin Gene-Related Peptide/metabolism
- Calcium Channels/genetics
- Calcium Channels/metabolism
- Disease Models, Animal
- Ganglia, Spinal/cytology
- Ganglia, Spinal/metabolism
- Hot Temperature
- Hyperalgesia/genetics
- Hyperalgesia/metabolism
- Hyperalgesia/physiopathology
- Immunohistochemistry
- Inflammation/genetics
- Inflammation/metabolism
- Inflammation/physiopathology
- Mechanoreceptors/cytology
- Mechanoreceptors/metabolism
- Mice
- Mice, Inbred C57BL
- Mice, Knockout
- Nerve Fibers, Myelinated/metabolism
- Nerve Fibers, Myelinated/ultrastructure
- Nerve Fibers, Unmyelinated/metabolism
- Nerve Fibers, Unmyelinated/ultrastructure
- Neurons, Afferent/cytology
- Neurons, Afferent/metabolism
- Nociceptors/metabolism
- Organ Culture Techniques
- Pain/genetics
- Pain/metabolism
- Pain/physiopathology
- Skin/innervation
- TRPV Cation Channels/genetics
- TRPV Cation Channels/metabolism
- Thermosensing/physiology
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Affiliation(s)
- Jeffrey J Lawson
- Department of Neurobiology, University of Pittsburgh School of Medicine, Pittsburgh, Pennsylvania 15261, USA
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Numata T, Shimizu T, Okada Y. TRPM7 is a stretch- and swelling-activated cation channel involved in volume regulation in human epithelial cells. Am J Physiol Cell Physiol 2007; 292:C460-7. [PMID: 16943238 DOI: 10.1152/ajpcell.00367.2006] [Citation(s) in RCA: 167] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Stretch- and swelling-activated cation (SSAC) channels play essential roles not only in sensing and transducing external mechanical stresses but also in regulating cell volume in living cells. However, the molecular nature of the SSAC channel has not been clarified. In human epithelial HeLa cells, single-channel recordings in cell-attached and inside-out patches revealed expression of a Mg2+- and Gd3+-sensitive nonselective cation channel that is exquisitely sensitive to membrane stretch. Whole cell recordings revealed that the macroscopic cationic currents exhibit transient receptor potential (TRP) melastatin (TRPM)7-like properties such as outward rectification and sensitivity to Mg2+ and Gd3+. The whole cell cation current was augmented by osmotic cell swelling. RT-PCR and Western blotting demonstrated molecular expression of TRPM7 in HeLa cells. Treatment with small interfering RNA (siRNA) targeted against TRPM7 led to abolition of single stretch-activated cation channel currents and of swelling-activated, whole cell cation currents in HeLa cells. The silencing of TRPM7 by siRNA reduced the rate of cell volume recovery after osmotic swelling. A similar inhibition of regulatory volume decrease was also observed when extracellular Ca2+ was removed or Gd3+ was applied. It is thus concluded that TRPM7 represents the SSAC channel endogenously expressed in HeLa cells and that, by serving as a swelling-induced Ca2+ influx pathway, it plays an important role in cell volume regulation.
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Affiliation(s)
- Tomohiro Numata
- Department of Cell Physiology, National Institute for Physiological Sciences, Okazaki 444-8585, Japan
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30
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MechanoTRPs and TRPA1. CURRENT TOPICS IN MEMBRANES 2007. [PMID: 25168138 DOI: 10.1016/s1063-5823(06)59008-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register]
Abstract
Genetic and molecular searches in animals identify two families of ion channels used by specialized mechanosensory cells. These are the degenerin/epithelial Na+ channels (Deg/ENaCs) and transient receptor potential (TRP) channels. Some of these channels open in response to mechanical forces and/or mediate cellular responses to mechanical stimulation. TRPA1 is expressed in nociceptive neurons of peripheral ganglia and in the sensory epithelia of the inner ear. In nociceptors, TRPA1 forms chemosensitive channels that mediate the response to exogenous pain-producing chemicals as well as to the endogenous proalgesic bradykinin (BK). More indirect evidence suggests that TRPA1 might also form mechanosensory channels. Some of the TRP channels that mediate mechanical responses are not necessarily mechanically gated. For example, TRPV4 mutant mice have reduced sensitivity to noxious tactile stimulation, and heterologously expressed TRPV4 opens in response to hypotonic solution (which induces cell swelling and thus stretches membranes). TRPA1 genes in mammals are large, occupy around 50kb of chromosomal DNA and are encoded by at least 27 exons. In humans, the TRPA1 gene is located on chromosome 8q13.
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31
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ENaC Proteins in Vascular Smooth Muscle Mechanotransduction. CURRENT TOPICS IN MEMBRANES 2007; 59:127-53. [DOI: 10.1016/s1063-5823(06)59006-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/05/2023]
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32
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Jernigan NL, Drummond HA. Myogenic vasoconstriction in mouse renal interlobar arteries: role of endogenous β and γENaC. Am J Physiol Renal Physiol 2006; 291:F1184-91. [PMID: 16849693 DOI: 10.1152/ajprenal.00177.2006] [Citation(s) in RCA: 89] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023] Open
Abstract
Mechanosensitive ion channels are thought to initiate pressure-induced vasoconstriction, however, the molecular identity of these channels is unknown. Recent work from our laboratory suggests that members of the Degenerin/Epithelial Na+ Channel (DEG/ENaC) family may be components of the mechanosensitive ion channel complex in vascular smooth muscle (VSM); however, the specific DEG/ENaC proteins mediating myogenic constriction are unknown. The goal of this study is to determine if specific knockdown of β or γENaC, using dominant-negative (DN) or small-interference RNA (siRNA) molecules, inhibits pressure-induced vasoconstriction in mouse renal interlobar arteries. To address this goal, isolated arteries were transiently transfected with β or γENaC DN-cDNA or siRNA molecules. After 24 h, vessels were either 1) cannulated and pressurized for pressure-diameter response curves or 2) dissociated and immunolabeled to determine VSM cell endogenous ENaC protein expression. We found that transfection of βENaC DN-cDNA or siRNA suppresses β-, but not γENaC protein expression. Similarly, γENaC DN-cDNA or siRNA suppresses γ-, but not βENaC protein expression. In addition, transfection of β- or γENaC DN-cDNA or siRNA molecules inhibits pressure-induced vasoconstriction, but does not block agonist-induced vasoconstriction. Our results provide the first direct evidence that β and γENaC proteins are essential in mediating myogenic vasoconstriction in mouse renal interlobar arteries.
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Affiliation(s)
- Nikki L Jernigan
- Department of Physiology and Biophysics, University of Mississippi Medical Center, 2500 North State St., Jackson, MS 39216, USA
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33
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Abstract
Vascular smooth muscle cell (VSMC) migration plays a key role in tissue repair after arterial wall injury. VSMC migration requires integration of chemical and mechanical signaling mechanisms. Recently, we showed that epithelial Na(+) channel (ENaC) proteins are expressed in VSMCs and that ENaC inhibition abolishes pressure-induced constriction in isolated artery segments. However, whether ENaC proteins play a role in VSMC migration is unknown. The goal of this study was to determine whether ENaC molecules are required for VSMC migration. Using RT-PCR, immunoblotting, and immunolabeling, we detected expression of alpha-, beta-, and gammaENaC transcripts and proteins in cultured VSMCs (SV40-LT and A10 cells). Of the three proteins, betaENaC was the most readily detected in both cell lines by immunolocalization and Western blotting. Inhibition of ENaC activity with 1 microM benzamil blunted VSMC migration associated with wound healing (40.3% at 8 h and 26.2% at 24 h) and in response to the chemotactic stimulant platelet-derived growth factor-BB (38.1%). Furthermore, silencing ENaC gene expression with small interfering RNA blunted VSMC migration. These data indicate that expression of ENaC proteins is required for normal VSMC migration and suggest a potential new role for ENaC proteins in vascular tissue repair.
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Affiliation(s)
- Samira C Grifoni
- Dept. of Physiology and Biophysics, University of Mississippi Medical Center, Jackson, MS 39216, USA
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34
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Willis WD. Chapter 3 The Nociceptive Membrane: Historical Overview. CURRENT TOPICS IN MEMBRANES 2006. [DOI: 10.1016/s1063-5823(06)57002-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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35
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Meyer J, Preyer S, Hofmann SI, Gummer AW. Tonic mechanosensitivity of outer hair cells after loss of tip links. Hear Res 2005; 202:97-113. [PMID: 15811703 DOI: 10.1016/j.heares.2004.11.013] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/01/2004] [Accepted: 11/30/2004] [Indexed: 11/16/2022]
Abstract
Tip links - the extracellular connectors between the distal ends of adjacent stereocilia - are essential for the fast mechanical gating of hair-cell transducer channels. Transduction in the absence of tip links was investigated for outer hair cells of the adult guinea-pig cochlea by patch-clamp recordings of the whole-cell current during mechanical stimulation of the hair bundle. Loss of tip links induced by application of BAPTA led to permanently opened transducer channels, as evidenced by a constant inward current, loss of response to sinusoidal mechanical deflection of the hair bundle and block by the open-channel blocker dihydrostreptomycin (100 microM). Step deflection of the hair bundle (200-500 nm) in the inhibitory direction exponentially reduced this current to a constant value with time constant, tau(on), of the order of seconds. The current returned exponentially to the pre-stimulus level with time-constant, tau(off), also of the order of seconds. tau(on) was dependent on the inter-stimulus interval, Deltat, such that reducing this interval below about 40 s resulted in an exponentially faster response. tau(off) was independent of Deltat. Application of the calcium ionophore, ionomycin (10 microM), showed that tau(on) became independent of Deltat after saturating elevation of the intracellular Ca(2+) concentration. Flash-photolytic release of intracellular caged calcium (25-microM NP-EGTA/AM) showed that tau(on) is dependent on intracellular Ca(2+) concentration. These experiments imply an intracellular, calcium-dependent gating mechanism for hair-cell transducer channels.
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Affiliation(s)
- Jens Meyer
- Department of Otolaryngology, Section of Physiological Acoustics and Communication, University of Tübingen, Germany
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36
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Melrose J, Smith S, Cake M, Read R, Whitelock J. Perlecan displays variable spatial and temporal immunolocalisation patterns in the articular and growth plate cartilages of the ovine stifle joint. Histochem Cell Biol 2005; 123:561-71. [PMID: 16021525 DOI: 10.1007/s00418-005-0789-y] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 03/03/2005] [Indexed: 11/29/2022]
Abstract
Perlecan is a modular heparan sulphate and/or chondroitin sulphate substituted proteoglycan of basement membrane, vascular tissues and cartilage. Perlecan acts as a low affinity co-receptor for fibroblast growth factors 1, 2, 7, 9, binds connective tissue growth factor and co-ordinates chondrogenesis, endochondral ossification and vascular remodelling during skeletal development; however, relatively little is known of its distribution in these tissues during ageing and development. The aim of the present study was to immunolocalise perlecan in the articular and epiphyseal growth plate cartilages of stifle joints in 2-day to 8-year-old pedigree merino sheep. Perlecan was prominent pericellularly in the stifle joint cartilages at all age points and also present in the inter-territorial matrix of the newborn to 19-month-old cartilage specimens. Aggrecan was part pericellular, but predominantly an extracellular proteoglycan. Perlecan was a prominent component of the long bone growth plates and displayed a pericellular as well as a strong ECM distribution pattern; this may indicate a so far unrecognised role for perlecan in the mineralisation of hypertrophic cartilage. A significant age dependant decline in cell number and perlecan levels was evident in the hyaline and growth plate cartilages. The prominent pericellular distribution of perlecan observed indicates potential roles in cell-matrix communication in cartilage, consistent with growth factor signalling, cellular proliferation and tissue development.
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Affiliation(s)
- James Melrose
- Raymond Purves Laboratory, Institute of Bone and Joint Research, University of Sydney at the Royal North Shore Hospital, St Leonards, NSW, 2065, Australia.
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37
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Jernigan NL, Drummond HA. Vascular ENaC proteins are required for renal myogenic constriction. Am J Physiol Renal Physiol 2005; 289:F891-901. [PMID: 15914781 DOI: 10.1152/ajprenal.00019.2005] [Citation(s) in RCA: 114] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The myogenic response is an essential component of renal blood flow autoregulation and is the inherent ability of vascular smooth muscle cells (VSMCs) to contract in response to increases in intraluminal pressure. Although mechanosensitive ion channels are thought to initiate VSMC stretch-induced contraction, their molecular identity is unknown. Recent reports suggest degenerin/epithelial Na(+) channels (DEG/ENaC) may form mechanotransducers in sensory neurons and VSMCs; however, the role of DEG/ENaC proteins in myogenic constriction of mouse renal arteries has not been established. To test the hypothesis that DEG/ENaC proteins are required for myogenic constriction in renal vessels, we first determined expression of ENaC transcripts and proteins in mouse renal VSMCs. Then, we determined pressure- and agonist-induced constriction and changes in vascular smooth muscle cytosolic Ca(2+) and Na(+) in isolated mouse renal interlobar arteries following DEG/ENaC inhibition with amiloride and benzamil. We detect alpha-, beta-, and gammaENaC transcript and protein expression in cultured mouse renal VSMC. In contrast, we detect only beta- and gamma- but not alphaENaC protein in freshly dispersed mrVMSC. Selective DEG/ENaC inhibition, with low doses of amiloride and benzamil, abolishes pressure-induced constriction and increases in cytosolic Ca(2+) and Na(+) without diminishing agonist-induced responses in isolated mouse interlobar arteries. Our findings indicate that DEG/ENaC proteins are required for myogenic constriction in mouse interlobar arteries and are consistent with our hypothesis that DEG/ENaC proteins may be components of mechanosensitive ion channel complexes required for myogenic vasoconstriction.
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Affiliation(s)
- Nikki L Jernigan
- Dept. of Physiology and Biophysics, Univ. of Mississippi Medical Center, 2500 North State St., Jackson, MS 39216, USA
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38
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Abstract
The adaptability of skeletal muscle to changes in the mechanical environment has been well characterized at the tissue and system levels, but the mechanisms through which mechanical signals are transduced to chemical signals that influence muscle growth and metabolism remain largely unidentified. However, several findings have suggested that mechanical signal transduction in muscle may occur through signaling pathways that are shared with insulin-like growth factor (IGF)-I. The involvement of IGF-I-mediated signaling for mechanical signal transduction in muscle was originally suggested by the observations that muscle releases IGF-I on mechanical stimulation, that IGF-I is a potent agent for promoting muscle growth and affecting phenotype, and that IGF-I can function as an autocrine hormone in muscle. Accumulating evidence shows that at least two signaling pathways downstream of IGF-I binding can influence muscle growth and adaptation. Signaling via the calcineurin/nuclear factor of activated T-cell pathway has been shown to have a powerful influence on promoting the slow/type I phenotype in muscle but can also increase muscle mass. Neural stimulation of muscle can activate this pathway, although whether neural activation of the pathway can occur independent of mechanical activation or independent of IGF-I-mediated signaling remains to be explored. Signaling via the Akt/mammalian target of rapamycin pathway can also increase muscle growth, and recent findings show that activation of this pathway can occur as a response to mechanical stimulation applied directly to muscle cells, independent of signals derived from other cells. In addition, mechanical activation of mammalian target of rapamycin, Akt, and other downstream signals is apparently independent of autocrine factors, which suggests that activation of the mechanical pathway occurs independent of muscle-mediated IGF-I release.
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Affiliation(s)
- James G Tidball
- Department of Physiological Science, 5833 Life Science Bldg., University of California, Los Angeles, CA 90095, USA.
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39
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McIlwrath SL, Hu J, Anirudhan G, Shin JB, Lewin GR. The sensory mechanotransduction ion channel ASIC2 (acid sensitive ion channel 2) is regulated by neurotrophin availability. Neuroscience 2005; 131:499-511. [PMID: 15708491 DOI: 10.1016/j.neuroscience.2004.11.030] [Citation(s) in RCA: 32] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/13/2004] [Indexed: 12/16/2022]
Abstract
Almost all sensory neurons of the dorsal root ganglia have a mechanosensitive receptive field in the periphery. We have shown that the sensitivity to mechanical stimuli of a subset of sensory neurons that are slowly adapting mechanoreceptors (SAM) is strongly dependent on the availability of brain-derived neurotrophic factor (BDNF). Here we have investigated whether the ASIC2 sodium channel, recently shown by us to be necessary for normal SAM sensitivity, might be regulated by BDNF and thus partially account for the down-regulation of SAM sensitivity seen in BDNF deficient mice. We show that the mRNA for ASIC2 channels is reduced in the DRG of BDNF deficient mice indicating that BDNF might maintain its expression in vivo. We also made short-term cultures of sensory neurons from adult BDNF deficient mice and used a specific antibody to detect the presence of ASIC2 channels in different classes of sensory neurons. We observed that the channel protein was dramatically down-regulated selectively in medium and large diameter neurons and this expression could be rescued in a dose and time dependent manner by addition of BDNF to the culture (10-100 ng/ml). Drugs that block new transcription or protein synthesis also prevented the rescue effects of BDNF. We observed that ASIC2 channels were down-regulated in sensory neurons taken from neurotrophin-4 and neurotrophin-3 deficient mice; these effects might be due to a selective loss of neurons that normally express large amounts of ASIC2 channels. In summary, our data identify the ASIC2 channel as a target of BDNF signaling in vivo and suggest that the functional down-regulation of sensory mechanotransduction in BDNF deficient mice is in part due to loss of ASIC2 expression.
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Affiliation(s)
- S L McIlwrath
- Growth Factors and Regeneration Group and Charité Universitätsmedizin Berlin, Max-Delbrück Center for Molecular Medicine, Robert-Rössle-Strasse 10, Buch D-13092 Berlin, Germany
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40
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Martinac B. Mechanosensitive ion channels: molecules of mechanotransduction. J Cell Sci 2004; 117:2449-60. [PMID: 15159450 DOI: 10.1242/jcs.01232] [Citation(s) in RCA: 353] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Cells respond to a wide variety of mechanical stimuli, ranging from thermal molecular agitation to potentially destructive cell swelling caused by osmotic pressure gradients. The cell membrane presents a major target of the external mechanical forces that act upon a cell, and mechanosensitive (MS) ion channels play a crucial role in the physiology of mechanotransduction. These detect and transduce external mechanical forces into electrical and/or chemical intracellular signals. Recent work has increased our understanding of their gating mechanism, physiological functions and evolutionary origins. In particular, there has been major progress in research on microbial MS channels. Moreover, cloning and sequencing of MS channels from several species has provided insights into their evolution, their physiological functions in prokaryotes and eukaryotes, and their potential roles in the pathology of disease.
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Affiliation(s)
- Boris Martinac
- School of Medicine and Pharmacology, QEII Medical Centre, University of Western Australia, Crawley, WA 6009, Australia.
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41
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Abstract
Increased sensitivity of cough pathways has been demonstrated in numerous studies. The underlying mechanisms of this sensitization are largely unknown; however, a burgeoning body of evidence suggests that vagal primary afferent neurones that innervate the airways are likely to be involved. This plasticity includes changes in anatomy, neurochemistry and function. PGE2 is an example of an inflammatory mediator that increases responsiveness to tussive stimuli. Electrophysiological studies of neurone cell bodies isolated from afferent ganglia have revealed that prostanoids modulate the function of a variety of distinct ion channels including those that carry TTX-insensitive voltage-gated sodium currents, slow post-spike hyperpolarizations and a hyperpolarization-activated cation current. Mediator-induced modulation of the function of various voltage-gated currents operating at the peripheral terminals of airway afferent neurons would probably influence input from the airways into the central nervous system and contribute to the urge to cough and increased responsiveness to tussive stimuli.
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Affiliation(s)
- Michael J Carr
- UCB Research Inc., 840 Memorial Drive, Cambridge, MA 02139, USA.
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42
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Syntichaki P, Tavernarakis N. Genetic Models of Mechanotransduction: The NematodeCaenorhabditis elegans. Physiol Rev 2004; 84:1097-153. [PMID: 15383649 DOI: 10.1152/physrev.00043.2003] [Citation(s) in RCA: 106] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022] Open
Abstract
Mechanotransduction, the conversion of a mechanical stimulus into a biological response, constitutes the basis for a plethora of fundamental biological processes such as the senses of touch, balance, and hearing and contributes critically to development and homeostasis in all organisms. Despite this profound importance in biology, we know remarkably little about how mechanical input forces delivered to a cell are interpreted to an extensive repertoire of output physiological responses. Recent, elegant genetic and electrophysiological studies have shown that specialized macromolecular complexes, encompassing mechanically gated ion channels, play a central role in the transformation of mechanical forces into a cellular signal, which takes place in mechanosensory organs of diverse organisms. These complexes are highly efficient sensors, closely entangled with their surrounding environment. Such association appears essential for proper channel gating and provides proximity of the mechanosensory apparatus to the source of triggering mechanical energy. Genetic and molecular evidence collected in model organisms such as the nematode worm Caenorhabditis elegans, the fruit fly Drosophila melanogaster, and the mouse highlight two distinct classes of mechanically gated ion channels: the degenerin (DEG)/epithelial Na+channel (ENaC) family and the transient receptor potential (TRP) family of ion channels. In addition to the core channel proteins, several other potentially interacting molecules have in some cases been identified, which are likely parts of the mechanotransducing apparatus. Based on cumulative data, a model of the sensory mechanotransducer has emerged that encompasses our current understanding of the process and fulfills the structural requirements dictated by its dedicated function. It remains to be seen how general this model is and whether it will withstand the impiteous test of time.
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Affiliation(s)
- Popi Syntichaki
- Institute of Molecular Biology and Biotechnology, Foundation for Research and Technology, Vassilika Vouton, PO Box 1527, Heraklion 71110, Crete, Greece
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43
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44
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TODI SOKOLV, SHARMA YASHODA, EBERL DANIELF. Anatomical and molecular design of the Drosophila antenna as a flagellar auditory organ. Microsc Res Tech 2004; 63:388-99. [PMID: 15252880 PMCID: PMC1805627 DOI: 10.1002/jemt.20053] [Citation(s) in RCA: 66] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
Abstract
The molecular basis of hearing is less well understood than many other senses. However, recent studies in Drosophila have provided some important steps towards a molecular understanding of hearing. In this report, we summarize these findings and their implications on the relationship between hearing and touch. In Drosophila, hearing is accomplished by Johnston's Organ, a chordotonal organ containing over 150 scolopidia within the second antennal segment. We will discuss anatomical features of the antenna and how they contribute to the function of this flagellar auditory receptor. The effects of several mutants, identified through mutagenesis screens or as homologues of vertebrate auditory genes, will be summarized. Based on evidence gathered from these studies, we propose a speculative model for how the chordotonal organ might function.
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Affiliation(s)
- SOKOL V. TODI
- Interdisciplinary Graduate Program in Neuroscience, The University of Iowa, Iowa City, Iowa 52242
- Department of Biological Sciences, The University of Iowa, Iowa City, Iowa 52242
| | - YASHODA SHARMA
- Department of Biological Sciences, The University of Iowa, Iowa City, Iowa 52242
| | - DANIEL F. EBERL
- Interdisciplinary Graduate Program in Neuroscience, The University of Iowa, Iowa City, Iowa 52242
- Department of Biological Sciences, The University of Iowa, Iowa City, Iowa 52242
- *Correspondence to: Daniel F. Eberl, Department of Biological Sciences, The University of Iowa, Iowa City, IA 52242-1324. E-mail:
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45
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Rowe MH, Peterson EH. Quantitative analysis of stereociliary arrays on vestibular hair cells. Hear Res 2004; 190:10-24. [PMID: 15051126 DOI: 10.1016/s0378-5955(03)00395-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/27/2003] [Revised: 11/25/2003] [Accepted: 11/25/2003] [Indexed: 11/30/2022]
Abstract
We have developed a method for quantifying the number, spacing, and distribution of stereocilia on the apical surface of hair cells using spatial autocorrelation analysis and statistics for directional data. Here, we illustrate the method using idealized hair bundles, and we apply it to scanning micrographs of turtle hair cells from the utricle and posterior canal, and to freeze-fracture preparations of bullfrog saccule. The analysis suggests three common features of stereociliary bundles. First, bundle geometries form a continuum from 'loose' to 'tight' rather than two distinct groups. Second, interciliary spacing along the three hexagon axes is not equal; spacing is usually widest along the hexagon axis closest to the bundle's axis of bilateral symmetry (the presumptive excitatory axis). Third, spacing between stereocilia changes with distance from the kinocilium. All three features will influence predictions of the tip link tensions that accompany bundle deflection.
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Affiliation(s)
- Michael H Rowe
- Neuroscience Program and Department of Biological Sciences, Ohio University, Athens, OH 45701, USA.
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46
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Nilius B, Vriens J, Prenen J, Droogmans G, Voets T. TRPV4 calcium entry channel: a paradigm for gating diversity. Am J Physiol Cell Physiol 2004; 286:C195-205. [PMID: 14707014 DOI: 10.1152/ajpcell.00365.2003] [Citation(s) in RCA: 353] [Impact Index Per Article: 17.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
The vanilloid receptor-1 (VR1, now TRPV1) was the founding member of a subgroup of cation channels within the TRP family. The TRPV subgroup contains six mammalian members, which all function as Ca2+ entry channels gated by a variety of physical and chemical stimuli. TRPV4, which displays 45% sequence identity with TRPV1, is characterized by a surprising gating promiscuity: it is activated by hypotonic cell swelling, heat, synthetic 4alpha-phorbols, and several endogenous substances including arachidonic acid (AA), the endocannabinoids anandamide and 2-AG, and cytochrome P-450 metabolites of AA, such as epoxyeicosatrienoic acids. This review summarizes data on TRPV4 as a paradigm of gating diversity in this subfamily of Ca2+ entry channels.
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Affiliation(s)
- Bernd Nilius
- Laboratorium voor Fysiologie, KU Leuven, Campus Gasthuisberg, 3000 Leuven, Belgium.
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47
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Abstract
Mechanosensitive ion channels are the primary transducers that convert mechanical force into an electrical or chemical signal in hearing, touch, and other mechanical senses. Unlike vision, olfaction, and some types of taste, which all use similar kinds of primary heterotrimeric GTP-binding protein-coupled receptors, mechanosensation relies on diverse types of transducer molecules. Unrelated types of channels can be used for the perception of various mechanical stimuli, not only in distant groups of organisms, but also in separate locations of the same organism. The extreme sensitivity of the transduction mechanism in the auditory system, which relies on an elaborate structure of rigid cilia, filamentous links, and molecular motors to focus force on transduction channels, contrasts with that of the bacterial channel MscL, which is opened by high lateral tension in the membrane and fulfills a safety-valve rather than a sensory function. The spatial scales of conformational movement and force in these two systems are described, and are shown to be consistent with a general physical description of mechanical channel gating. We outline the characteristics of several types of mechanosensitive channels and the functional contexts in which they participate in signaling and cellular regulation in sensory and nonsensory cells.
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Affiliation(s)
- Sergei Sukharev
- Department of Biology, University of Maryland, College Park, MD 20742, USA.
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48
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Abstract
Pain, due to mechanical stimuli, is a normal, indeed healthy, response of animals to potential or actual damage to tissues. Mammals in general, and humans in particular, have evolved a highly sophisticated system of pain perception, which is characterized in humans by complementary but distinct neural processing of the intensity and location of a noxious stimulus, and a motivational/emotional or affective response to the stimulus. The peripheral and central neurons that comprise this system, which has been called the 'neuromatrix', dynamically (temporally) respond and adapt to noxious biomechanical stimuli. However, phenotypic variability of the neuromatrix can be large, which can result in a host of musculoskeletal conditions that are characterized by altered pain perception, which can and often does alter the course of the condition. This neural plasticity has been well recognized in the central nervous system, but it has only more recently become known that peripheral nociceptors also adapt to their altered extracellular matrix environment. This work reviews the biomechanics of pain focusing on the relevant stimulus that initiates responses by nociceptors to the cognitive perception of pain.
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Affiliation(s)
- Partap S Khalsa
- Department of Biomedical Engineering, State University of New York at Stony Brook, HSC T18-030 Stony Brook, NY 11794-8181, USA.
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49
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Yoshimura H, Tada T, Iida H. Subcellular localization and oligomeric structure of the yeast putative stretch-activated Ca2+ channel component Mid1. Exp Cell Res 2004; 293:185-95. [PMID: 14729456 DOI: 10.1016/j.yexcr.2003.09.020] [Citation(s) in RCA: 37] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The yeast Mid1 protein with an apparent molecular mass of 100 kDa is required for Ca2+ influx stimulated by the mating pheromone and by a capacitative calcium entrylike mechanism acting in response to Ca2+ depletion from the endoplasmic reticulum (ER) and functions as a stretch-activated Ca2+ -permeable channel when expressed in mammalian cells. Our previous work with protease protection experiments has indicated that Mid1 is present in the plasma membrane. In this study, we examined a possible intracellular localization of this protein by indirect fluorescence microscopy and found that Mid1 is present in the ER membrane as well as the plasma membrane. Intracellular fluorescence images for Mid1 were the same as those for the ER marker protein Sec71 but quite different from those of the Golgi protein Ypt1. The results were confirmed by membrane fractionation using Angiografin density gradient analysis. We also investigated the oligomeric structures and protein levels of Mid1 and found that Mid1 forms a 200-kDa oligomer by disulfide bonding. The protein level and modification of Mid1 in the plasma membrane and the ER membrane were unchanged by the mating pheromone. These findings provide new insight into the function of Mid1 in relation to localization, modification, and activation mechanisms.
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Affiliation(s)
- Hitoshi Yoshimura
- Department of Biology, Tokyo Gakugei University, 4-1-1 Nukui kita-machi, Koganei-shi, Tokyo 184-8501, Japan
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