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Niloy SI, Strege PR, Hannan EC, Cowan LM, Linsenmeier F, Friedrich O, Farrugia G, Beyder A. Stretch response of the mechano-gated channel TMEM63A in membrane patches and single cells. Am J Physiol Cell Physiol 2024; 326:C622-C631. [PMID: 38189136 PMCID: PMC11193453 DOI: 10.1152/ajpcell.00583.2023] [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: 11/01/2023] [Revised: 12/20/2023] [Accepted: 12/22/2023] [Indexed: 01/09/2024]
Abstract
The recently discovered ion channel TMEM63A has biophysical features distinctive for mechano-gated cation channels, activating at high pressures with slow kinetics while not inactivating. However, some biophysical properties are less clear, including no information on its function in whole cells. The aim of this study is to expand the TMEM63A biophysical characterization and examine the function in whole cells. Piezo1-knockout HEK293T cells were cotransfected with human TMEM63A and green fluorescent protein (GFP), and macroscopic currents in cell-attached patches were recorded by high-speed pressure clamp at holding voltages from -120 to -20 mV with 0-100 mmHg patch suction for 1 s. HEK293 cells cotransfected with TMEM63A and GCaMP5 were seeded onto polydimethylsiloxane (PDMS) membrane, and the response to 3-12 s of 1%-15% whole cell isotropic (equi-biaxial) stretch induced by an IsoStretcher was measured by the change in intracellular calcium ([Ca2+]i) and presented as (ΔF/F0 > 1). Increasing patch pressures activated TMEM63A currents with accelerating activation kinetics and current amplitudes that were pressure dependent but voltage independent. TMEM63A currents were plateaued within 2 s, recovered quickly, and were sensitive to Gd3+. In whole cells stretched on flexible membranes, radial stretch increased the [Ca2+]i responses in a larger proportion of cells cotransfected with TMEM63A and GCaMP5 than GCaMP5-only controls. TMEM63A currents are force activated and voltage insensitive, have a high threshold for pressure activation with slow activation and deactivation, and lack inactivation over 5 s. TMEM63A has the net polarity and kinetics that would depolarize plasma membranes and increase inward currents, contributing to a sustained [Ca2+]i increase in response to high stretch.NEW & NOTEWORTHY TMEM63A has biophysical features distinctive for mechano-gated cation channels, but some properties are less clear, including no functional information in whole cells. We report that pressure-dependent yet voltage-independent TMEM63A currents in cell membrane patches correlated with cell size. In addition, radial stretch of whole cells on flexible membranes increased the [Ca2+]i responses more in TMEM63A-transfected cells. Inward TMEM63A currents in response to high stretch can depolarize plasma membranes and contribute to a sustained [Ca2+]i increase.
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Affiliation(s)
- Sayeman Islam Niloy
- Enteric Neuroscience Program (ENSP), Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota, United States
| | - Peter R Strege
- Enteric Neuroscience Program (ENSP), Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota, United States
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, United States
| | - Elizabeth C Hannan
- Enteric Neuroscience Program (ENSP), Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota, United States
| | - Luke M Cowan
- Enteric Neuroscience Program (ENSP), Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota, United States
| | - Fabian Linsenmeier
- Institute of Medical Biotechnology, Department of Chemical and Biological Engineering, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Oliver Friedrich
- Institute of Medical Biotechnology, Department of Chemical and Biological Engineering, Friedrich-Alexander University Erlangen-Nürnberg, Erlangen, Germany
| | - Gianrico Farrugia
- Enteric Neuroscience Program (ENSP), Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota, United States
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, United States
| | - Arthur Beyder
- Enteric Neuroscience Program (ENSP), Division of Gastroenterology and Hepatology, Mayo Clinic, Rochester, Minnesota, United States
- Department of Physiology and Biomedical Engineering, Mayo Clinic, Rochester, Minnesota, United States
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Yu D, Ahmed A, Jayasi J, Womac A, Sally O, Bae C. Inflammation condition sensitizes Piezo1 mechanosensitive channel in mouse cerebellum astrocyte. Front Cell Neurosci 2023; 17:1200946. [PMID: 37305437 PMCID: PMC10248153 DOI: 10.3389/fncel.2023.1200946] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2023] [Accepted: 05/12/2023] [Indexed: 06/13/2023] Open
Abstract
Piezo1 mechanosensitive ion channel (MSC) plays a significant role in human physiology. Despite several research on the function and expression of Piezo1 in the nervous system, its electrophysiological properties in neuroinflammatory astrocytes remain unknown. We tested whether astrocytic neuroinflammatory state regulates Piezo1 using electrical recordings, calcium imaging, and wound healing assays on cultured astrocytes. In this study, we determined whether neuroinflammatory condition regulates astrocytic Piezo1 currents in astrocytes. First, we performed electrophysiological recordings on the mouse cerebellum astrocytes (C8-S) under lipopolysaccharide (LPS)-induced neuroinflammatory condition. We found that LPS treatment significantly increased MSC currents in C8-S. The half-maximal pressure of LPS treated MSC currents was left-shifted but the slope sensitivity was not altered by LPS treatment. LPS-induced increase of MSC currents were further augmented by Piezo1 agonist, Yoda1 but were normalized by Piezo1 inhibitor, GsMTx4. Furthermore, silencing Piezo1 in LPS treated C8-S normalized not only MSC currents but also calcium influx and cell migration velocity. Together, our results show that LPS sensitized Piezo1 channel in C8-S astrocytes. These findings will suggest that astrocytic Piezo1 is a determinant of neuroinflammation pathogenesis and may in turn become the foundation of further research into curing several neuronal illnesses and injury related inflammation of neuronal cells.
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Miles L, Powell J, Kozak C, Song Y. Mechanosensitive Ion Channels, Axonal Growth, and Regeneration. Neuroscientist 2022:10738584221088575. [PMID: 35414308 PMCID: PMC9556659 DOI: 10.1177/10738584221088575] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Cells sense and respond to mechanical stimuli by converting those stimuli into biological signals, a process known as mechanotransduction. Mechanotransduction is essential in diverse cellular functions, including tissue development, touch sensitivity, pain, and neuronal pathfinding. In the search for key players of mechanotransduction, several families of ion channels were identified as being mechanosensitive and were demonstrated to be activated directly by mechanical forces in both the membrane bilayer and the cytoskeleton. More recently, Piezo ion channels were discovered as a bona fide mechanosensitive ion channel, and its characterization led to a cascade of research that revealed the diverse functions of Piezo proteins and, in particular, their involvement in neuronal repair.
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Affiliation(s)
- Leann Miles
- The Graduate Group in Biochemistry and Molecular Biophysics, University of Pennsylvania, Philadelphia, PA, USA
| | - Jackson Powell
- Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Casey Kozak
- Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA
| | - Yuanquan Song
- The Graduate Group in Biochemistry and Molecular Biophysics, University of Pennsylvania, Philadelphia, PA, USA.,Raymond G. Perelman Center for Cellular and Molecular Therapeutics, The Children's Hospital of Philadelphia, Philadelphia, PA, USA.,Department of Pathology and Laboratory Medicine, University of Pennsylvania, Philadelphia, PA, USA
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Pregabalin-induced neuroprotection and gait improvement in dystrophic MDX mice. Mol Cell Neurosci 2021; 114:103632. [PMID: 34058345 DOI: 10.1016/j.mcn.2021.103632] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2021] [Revised: 05/16/2021] [Accepted: 05/25/2021] [Indexed: 11/21/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is a genetic disease linked to the X chromosome induced by mutations in the dystrophin gene. Neuroprotective drugs, such as pregabalin (PGB), can improve motor function through the modulation of excitatory synapses, together with anti-apoptotic and anti-inflammatory effects. The present work studied the effects of PGB in the preservation of dystrophic peripheral nerves, allowing motor improvements in MDX mice. Five weeks old MDX and C57BL/10 mice were treated with PGB (30 mg/kg/day, i.p.) or vehicle, for 28 consecutive days. The mice were sacrificed on the 9th week, the sciatic nerves were dissected out and processed for immunohistochemistry and qRT-PCR, for evaluating the expression of proteins and gene transcripts related to neuronal activity and Schwann cell function. The lumbar spinal cords were also processed for qRT-PCR to evaluate the expression of neurotrophic factors and pro- and anti-inflammatory cytokines. Cranial tibial muscles were dissected out for endplate evaluation with α-bungarotoxin. The recovery of motor function was monitored throughout the treatment, using a spontaneous walking track test (Catwalk system) and a forced locomotion test (Rotarod). The results showed that treatment with PGB reduced the retrograde effects of muscle degeneration/regeneration on the nervous system from the 5th to the 9th week in MDX mice. Thus, PGB induced protein expression in neurons and Schwann cells, protecting myelinated fibers. In turn, better axonal morphology and close-to-normal motor endplates were observed. Indeed, such effects resulted in improved motor coordination of dystrophic animals. We believe that treatment with PGB improved the balance between excitatory and inhibitory inputs to spinal motoneurons, increasing motor control. In addition, PGB enhanced peripheral nerve homeostasis, by positively affecting Schwann cells. In general, the present results indicate that pregabalin is effective in protecting the PNS during the development of DMD, improving motor coordination, indicating possible translation to the clinic.
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Botter A, Vieira TM, Geri T, Roatta S. The peripheral origin of tap-induced muscle contraction revealed by multi-electrode surface electromyography in human vastus medialis. Sci Rep 2020; 10:2256. [PMID: 32041996 PMCID: PMC7010771 DOI: 10.1038/s41598-020-59122-z] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2019] [Accepted: 01/21/2020] [Indexed: 11/08/2022] Open
Abstract
It is well established that muscle percussion may lead to the excitation of muscle fibres. It is still debated, however, whether the excitation arises directly at the percussion site or reflexively, at the end plates. Here we sampled surface electromyograms (EMGs) from multiple locations along human vastus medialis fibres to address this issue. In five healthy subjects, contractions were elicited by percussing the distal fibre endings at different intensities (5-50 N), and the patellar tendon. EMGs were detected with two 32-electrode arrays, positioned longitudinally and transversally to the percussed fibres, to detect the origin and the propagation of action potentials and their spatial distribution across vastus medialis. During muscle percussion, compound action potentials were first observed at the electrode closest to the tapping site with latency smaller than 5 ms, and spatial extension confined to the percussed strip. Conversely, during tendon tap (and voluntary contractions), action potentials were first detected by electrodes closest to end plates and at a greater latency (mean ± s.d., 28.2 ± 1.7 ms, p < 0.001). No evidence of reflex responses to muscle tap was observed. Multi-electrode surface EMGs allowed for the first time to unequivocally and quantitatively describe the non-reflex nature of the response evoked by a muscle tap.
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Affiliation(s)
- Alberto Botter
- Laboratory for Engineering of the Neuromuscular System (LISiN), Department of Electronics and Telecommunications, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129, Turin, Italy
- PoliToBIOMed Lab, Politecnico di Torino, Turin, Italy
| | - Taian M Vieira
- Laboratory for Engineering of the Neuromuscular System (LISiN), Department of Electronics and Telecommunications, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129, Turin, Italy
- PoliToBIOMed Lab, Politecnico di Torino, Turin, Italy
| | - Tommaso Geri
- Department of Neuroscience, Rehabilitation, Ophthalmology, Genetics, Maternal and Child Health (DINOGMI), University of Genova, Campus of Savona, via Magliotto 2, 17100, Savona, Italy
| | - Silvestro Roatta
- Integrative Physiology Lab, Dept. of Neuroscience, University of Torino, Torino, c.so Raffaello 30, 10125, Torino, Italy.
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Reyngoudt H, Lopez Kolkovsky AL, Carlier PG. Free intramuscular Mg 2+ concentration calculated using both 31 P and 1 H NMRS-based pH in the skeletal muscle of Duchenne muscular dystrophy patients. NMR IN BIOMEDICINE 2019; 32:e4115. [PMID: 31184793 DOI: 10.1002/nbm.4115] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Revised: 04/03/2019] [Accepted: 04/23/2019] [Indexed: 06/09/2023]
Abstract
Early studies have demonstrated that (total) magnesium was decreased in skeletal muscle of Duchenne muscular dystrophy (DMD) patients. Free intramuscular Mg2+ can be derived from 31 P NMRS measurements. The value of free intramuscular magnesium concentration ([Mg2+ ]) is highly dependent on precise knowledge of intracellular pH, which is abnormally alkaline in dystrophic muscle, possibly due to an expanded interstitial space, potentially causing an underestimation of [Mg2+ ]. We have recently shown that intracellular pH can be derived using 1 H NMRS of carnosine. Our aim was to determine whether 31 P NMRS-based [Mg2+ ] is, in fact, abnormally low in DMD patients, taking advantage of the 1 H NMRS-based pH. A comparative analysis was, therefore, made between [Mg2+ ] values calculated with both 1 H and 31 P NMRS-based approaches to determine pH in 25 DMD patients, on a 3-T clinical NMR scanner. [Mg2+ ] was also assessed with 31 P NMRS only in (forearm or leg) skeletal muscle of 60 DMD patients and 63 age-matched controls. Additionally, phosphodiester levels as well as quantitative NMRI indices including water T2 , fat fraction, contractile cross-sectional area and one-year changes were evaluated. The main finding was that the significant difference in [Mg2+ ] between DMD patients and controls was preserved even when the intracellular pH determined with 1 H NMRS was similar in both groups. Consequently, we observed that [Mg2+ ] is significantly lower in DMD patients compared with controls in the larger database where only 31 P NMRS data were obtained. Significant yet weak correlations existed between [Mg2+ ] and PDE, water T2 and fat fraction. We concluded that low [Mg2+ ] is an actual finding in DMD, whether intracellular pH is normal or alkaline, and that it is a likely consequence of membrane leakiness. The response of Mg2+ to therapeutic treatment remains to be investigated in neuromuscular disorders. Free [Mg2+ ] determination with 31 P NMRS is highly dependent on a precise knowledge of intracellular pH. The pH of Duchenne muscular dystrophy (DMD) patients, as determined by 31 P NMRS, is abnormally alkaline. We have recently shown that intracellular pH could be determined using 1 H NMRS of carnosine, and that intracellular pH was alkaline in a proportion of, but not all, DMD patients with a 31 P NMRS-based alkaline pH. Taking advantage of this 1 H NMRS-based intracellular pH, we found that free intramuscular [Mg2+ ] is in fact abnormally low in DMD patients.
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Affiliation(s)
- Harmen Reyngoudt
- NMR Laboratory, Neuromuscular Investigation Center, Institute of Myology, Paris, France
- NMR Laboratory, CEA/DRF/IBFJ/MIRCen, Paris, France
| | - Alfredo L Lopez Kolkovsky
- NMR Laboratory, Neuromuscular Investigation Center, Institute of Myology, Paris, France
- NMR Laboratory, CEA/DRF/IBFJ/MIRCen, Paris, France
| | - Pierre G Carlier
- NMR Laboratory, Neuromuscular Investigation Center, Institute of Myology, Paris, France
- NMR Laboratory, CEA/DRF/IBFJ/MIRCen, Paris, France
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Robertson SN, Campsie P, Childs PG, Madsen F, Donnelly H, Henriquez FL, Mackay WG, Salmerón-Sánchez M, Tsimbouri MP, Williams C, Dalby MJ, Reid S. Control of cell behaviour through nanovibrational stimulation: nanokicking. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2018; 376:20170290. [PMID: 29661978 PMCID: PMC5915650 DOI: 10.1098/rsta.2017.0290] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 03/07/2018] [Indexed: 05/05/2023]
Abstract
Mechanical signals are ubiquitous in our everyday life and the process of converting these mechanical signals into a biological signalling response is known as mechanotransduction. Our understanding of mechanotransduction, and its contribution to vital cellular responses, is a rapidly expanding field of research involving complex processes that are still not clearly understood. The use of mechanical vibration as a stimulus of mechanotransduction, including variation of frequency and amplitude, allows an alternative method to control specific cell behaviour without chemical stimulation (e.g. growth factors). Chemical-independent control of cell behaviour could be highly advantageous for fields including drug discovery and clinical tissue engineering. In this review, a novel technique is described based on nanoscale sinusoidal vibration. Using finite-element analysis in conjunction with laser interferometry, techniques that are used within the field of gravitational wave detection, optimization of apparatus design and calibration of vibration application have been performed. We further discuss the application of nanovibrational stimulation, or 'nanokicking', to eukaryotic and prokaryotic cells including the differentiation of mesenchymal stem cells towards an osteoblast cell lineage. Mechanotransductive mechanisms are discussed including mediation through the Rho-A kinase signalling pathway. Optimization of this technique was first performed in two-dimensional culture using a simple vibration platform with an optimal frequency and amplitude of 1 kHz and 22 nm. A novel bioreactor was developed to scale up cell production, with recent research demonstrating that mesenchymal stem cell differentiation can be efficiently triggered in soft gel constructs. This important step provides first evidence that clinically relevant (three-dimensional) volumes of osteoblasts can be produced for the purpose of bone grafting, without complex scaffolds and/or chemical induction. Initial findings have shown that nanovibrational stimulation can also reduce biofilm formation in a number of clinically relevant bacteria. This demonstrates additional utility of the bioreactor to investigate mechanotransduction in other fields of research.This article is part of a discussion meeting issue 'The promises of gravitational-wave astronomy'.
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Affiliation(s)
- Shaun N Robertson
- SUPA, Department of Biomedical Engineering, University of Strathclyde, Graham Hills, 50 George Street, Glasgow G1 1QE, UK
| | - Paul Campsie
- SUPA, Department of Biomedical Engineering, University of Strathclyde, Graham Hills, 50 George Street, Glasgow G1 1QE, UK
| | - Peter G Childs
- Division of Biomedical Engineering, School of Engineering, University of Glasgow, Glasgow G12 8QQ, UK
| | - Fiona Madsen
- Institute of Healthcare, Policy and Practice, School of Health, Nursing and Midwifery, University of the West of Scotland, Paisley PA1 2BE, UK
| | - Hannah Donnelly
- Centre for Cell Engineering, Institute for Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Fiona L Henriquez
- Institute of Biomedical and Environmental Health Research, School of Science and Sport, University of the West of Scotland, Paisley PA1 2BE, UK
| | - William G Mackay
- Institute of Healthcare, Policy and Practice, School of Health, Nursing and Midwifery, University of the West of Scotland, Paisley PA1 2BE, UK
| | - Manuel Salmerón-Sánchez
- Division of Biomedical Engineering, School of Engineering, University of Glasgow, Glasgow G12 8QQ, UK
| | - Monica P Tsimbouri
- Centre for Cell Engineering, Institute for Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Craig Williams
- Institute of Healthcare, Policy and Practice, School of Health, Nursing and Midwifery, University of the West of Scotland, Paisley PA1 2BE, UK
| | - Matthew J Dalby
- Centre for Cell Engineering, Institute for Molecular, Cell and Systems Biology, College of Medical, Veterinary and Life Sciences, University of Glasgow, Glasgow G12 8QQ, UK
| | - Stuart Reid
- SUPA, Department of Biomedical Engineering, University of Strathclyde, Graham Hills, 50 George Street, Glasgow G1 1QE, UK
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Reyngoudt H, Turk S, Carlier PG. 1 H NMRS of carnosine combined with 31 P NMRS to better characterize skeletal muscle pH dysregulation in Duchenne muscular dystrophy. NMR IN BIOMEDICINE 2018; 31:e3839. [PMID: 29130550 DOI: 10.1002/nbm.3839] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/09/2017] [Revised: 09/06/2017] [Accepted: 09/07/2017] [Indexed: 05/18/2023]
Abstract
In recent years, quantitative nuclear magnetic resonance imaging and spectroscopy (NMRI and NMRS) have been used more systematically as outcome measures in natural history and clinical trial studies for Duchenne muscular dystrophy (DMD). Whereas most of these studies have emphasized the evaluation of the fat fraction as an assessment for disease severity, less focus has been placed on metabolic indices measured by NMRS. 31 P NMRS in DMD reveals an alkaline inorganic phosphate (Pi ) pool, originating from either leaky dystrophic myocytes or an increased interstitial space. 1 H NMRS, exploiting the pH-sensitive proton resonances of carnosine, an intracellular dipeptide, was used to distinguish between these two hypotheses. NMR data were obtained in 23 patients with DMD and 14 healthy subjects on a 3-T clinical NMR system. Both 31 P and 1 H NMRS data were acquired at the level of the gastrocnemius medialis muscle. A multi-slice multi-echo imaging acquisition was performed for the determination of water T2 and fat fraction in the same region of interest. Whereas nearly all patients with DMD showed an elevated pH compared with healthy controls when using 31 P NMRS, 1 H NMRS-determined pH was not systematically increased. As expected, the carnosine-based intracellular pH was never found to be alkaline in the absence of a concurrent Pi -based pH elevation. In addition, abnormal intracellular pH, based on carnosine, was never associated with normal water T2 values. We conclude that, in one group of patients, both 1 H and 31 P NMRS showed an alkaline pH, originating from the intracellular compartment and reflecting ionic dysregulation in dystrophic myocytes. In the other patients with DMD, intracellular pH was normal, but an alkaline Pi pool was still present, suggesting an extracellular origin, probably revealing an expanded interstitial volume fraction, often associated with fibrotic changes. The data demonstrate that 1 H NMRS could serve as a biomarker to assess the normalization of intramyocytic pH and sarcolemmal permeability following therapy inducing dystrophin expression in patients with DMD.
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Affiliation(s)
- Harmen Reyngoudt
- NMR Laboratory, Institute of Myology, Paris, France
- CEA, DRF, IBFJ, MIRCen, Paris, France
| | - Suna Turk
- NMR Laboratory, Institute of Myology, Paris, France
- CEA, DRF, IBFJ, MIRCen, Paris, France
| | - Pierre G Carlier
- NMR Laboratory, Institute of Myology, Paris, France
- CEA, DRF, IBFJ, MIRCen, Paris, France
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10
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Gaffney CJ, Shephard F, Chu J, Baillie DL, Rose A, Constantin-Teodosiu D, Greenhaff PL, Szewczyk NJ. Degenerin channel activation causes caspase-mediated protein degradation and mitochondrial dysfunction in adult C. elegans muscle. J Cachexia Sarcopenia Muscle 2016; 7:181-92. [PMID: 27493871 PMCID: PMC4864282 DOI: 10.1002/jcsm.12040] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/21/2014] [Revised: 03/17/2015] [Accepted: 04/09/2015] [Indexed: 12/28/2022] Open
Abstract
BACKGROUND Declines in skeletal muscle structure and function are found in various clinical populations, but the intramuscular proteolytic pathways that govern declines in these individuals remain relatively poorly understood. The nematode Caenorhabditis elegans has been developed into a model for identifying and understanding these pathways. Recently, it was reported that UNC-105/degenerin channel activation produced muscle protein degradation via an unknown mechanism. METHODS Generation of transgenic and double mutant C. elegans, RNAi, and drug treatments were utilized to assess molecular events governing protein degradation. Western blots were used to measure protein content. Cationic dyes and adenosine triphosphate (ATP) production assays were utilized to measure mitochondrial function. RESULTS unc-105 gain-of-function mutants display aberrant muscle protein degradation and a movement defect; both are reduced in intragenic revertants and in let-2 mutants that gate the hyperactive UNC-105 channel. Degradation is not suppressed by interventions suppressing proteasome-mediated, autophagy-mediated, or calpain-mediated degradation nor by suppressors of degenerin-induced neurodegeneration. Protein degradation, but not the movement defect, is decreased by treatment with caspase inhibitors or RNAi against ced-3 or ced-4. Adult unc-105 muscles display a time-dependent fragmentation of the mitochondrial reticulum that is associated with impaired mitochondrial membrane potential and that correlates with decreased rates of maximal ATP production. Reduced levels of CED-4, which is sufficient to activate CED-3 in vitro, are observed in unc-105 mitochondrial isolations. CONCLUSIONS Constitutive cationic influx into muscle appears to cause caspase degradation of cytosolic proteins as the result of mitochondrial dysfunction, which may be relevant to ageing and sarcopenia.
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Affiliation(s)
- Christopher J Gaffney
- MRC/ARUK Centre for Musculoskeletal Ageing Research, Faculty of Medicine and Health Sciences University of Nottingham Nottingham NG7 2UH UK
| | - Freya Shephard
- MRC/ARUK Centre for Musculoskeletal Ageing Research, Faculty of Medicine and Health Sciences University of Nottingham Nottingham NG7 2UH UK
| | - Jeff Chu
- Department of Molecular Biology and Biochemistry Simon Fraser University Burnaby BCV5A 1S6 Canada; Department of Medical Genetics University of British Columbia Vancouver BCV6T 1Z4 Canada
| | - David L Baillie
- Department of Molecular Biology and Biochemistry Simon Fraser University Burnaby BC V5A 1S6 Canada
| | - Ann Rose
- Department of Medical Genetics University of British Columbia Vancouver BC V6T 1Z4 Canada
| | - Dumitru Constantin-Teodosiu
- MRC/ARUK Centre for Musculoskeletal Ageing Research, Faculty of Medicine and Health Sciences University of Nottingham Nottingham NG7 2UH UK
| | - Paul L Greenhaff
- MRC/ARUK Centre for Musculoskeletal Ageing Research, Faculty of Medicine and Health Sciences University of Nottingham Nottingham NG7 2UH UK
| | - Nathaniel J Szewczyk
- MRC/ARUK Centre for Musculoskeletal Ageing Research, Faculty of Medicine and Health Sciences University of Nottingham Nottingham NG7 2UH UK
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Randhawa PK, Jaggi AS. Gadolinium and ruthenium red attenuate remote hind limb preconditioning-induced cardioprotection: possible role of TRP and especially TRPV channels. Naunyn Schmiedebergs Arch Pharmacol 2016; 389:887-96. [PMID: 27118661 DOI: 10.1007/s00210-016-1251-5] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/09/2015] [Accepted: 04/20/2016] [Indexed: 01/16/2023]
Abstract
Remote ischemic preconditioning is a well reported therapeutic strategy that induces cardioprotective effects but the underlying intracellular mechanisms have not been widely explored. The current study was designed to investigate the involvement of TRP and especially TRPV channels in remote hind limb preconditioning-induced cardioprotection. Remote hind limb preconditioning stimulus (4 alternate cycles of inflation and deflation of 5 min each) was delivered using a blood pressure cuff tied on the hind limb of the anesthetized rat. Using Langendorff's system, the heart was perfused and subjected to 30-min ischemia and 120-min reperfusion. The myocardial injury was assessed by measuring infarct size, lactate dehydrogenase (LDH), creatine kinase (CK), LVDP, +dp/dtmax, -dp/dtmin, heart rate, and coronary flow rate. Gadolinium, TRP blocker, and ruthenium red, TRPV channel blocker, were employed as pharmacological tools. Remote hind limb preconditioning significantly reduced the infarct size, LDH release, CK release and improved coronary flow rate, hemodynamic parameters including LVDP, +dp/dtmax, -dp/dtmin, and heart rate. However, gadolinium (7.5 and 15 mg kg(-1)) and ruthenium red (4 and 8 mg kg(-1)) significantly attenuated the cardioprotective effects suggesting the involvement of TRP especially TRPV channels in mediating remote hind limb preconditioning-induced cardioprotection. Remote hind limb preconditioning stimulus possibly activates TRPV channels on the heart or sensory nerve fibers innervating the heart to induce cardioprotective effects. Alternatively, remote hind limb preconditioning stimulus may also activate the mechanosensitive TRP and especially TRPV channels on the sensory nerve fibers innervating the skeletal muscles to trigger cardioprotective neurogenic signaling cascade. The cardioprotective effects of remote hind limb preconditioning may be mediated via activation of mechanosensitive TRP and especially TRPV channels.
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Affiliation(s)
- Puneet Kaur Randhawa
- Department of Pharmaceutical Sciences and Drug Research, Punjabi University, Patiala, 147002, India
| | - Amteshwar Singh Jaggi
- Department of Pharmaceutical Sciences and Drug Research, Punjabi University, Patiala, 147002, India.
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Abstract
Duchenne muscular dystrophy is a progressive, fatal, X-linked disease caused by a failure to accumulate the cytoskeletal protein dystrophin. This disease has been studied using a variety of animal models including fish, mice, rats, and dogs. While these models have contributed substantially to our mechanistic understanding of the disease and disease progression, limitations inherent to each model have slowed the clinical advancement of therapies, which necessitates the development of novel large-animal models. Several porcine dystrophin-deficient models have been identified, although disease severity may be so severe as to limit their potential contributions to the field. We have recently identified and completed the initial characterization of a natural porcine model of dystrophin insufficiency. Muscles from these animals display characteristic focal necrosis concomitant with decreased abundance and localization of dystrophin-glycoprotein complex components. These pigs recapitulate many of the cardinal features of muscular dystrophy, have elevated serum creatine kinase activity, and preliminarily appear to display altered locomotion. They also suffer from sudden death preceded by EKG abnormalities. Pig dystrophinopathy models could allow refinement of dosing strategies in human-sized animals in preparation for clinical trials. From an animal handling perspective, these pigs can generally be treated normally, with the understanding that acute stress can lead to sudden death. In summary, the ability to create genetically modified pig models and the serendipitous discovery of genetic disease in the swine industry has resulted in the emergence of new animal tools to facilitate the critical objective of improving the quality and length of life for boys afflicted with such a devastating disease.
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Affiliation(s)
- Joshua T Selsby
- Joshua T. Selsby, PhD, and Jason W. Ross, PhD are associate professors of Animal Science at Iowa State University, Ames, IA 50011. Dan Nonneman, PhD, is a research molecular biologist at the USDA, ARS, U.S. Meat Animal Research Center, Clay Center, NE 68933. Katrin Hollinger, PhD, was a graduate student in Genetics at Iowa State University, Ames, IA 50011
| | - Jason W Ross
- Joshua T. Selsby, PhD, and Jason W. Ross, PhD are associate professors of Animal Science at Iowa State University, Ames, IA 50011. Dan Nonneman, PhD, is a research molecular biologist at the USDA, ARS, U.S. Meat Animal Research Center, Clay Center, NE 68933. Katrin Hollinger, PhD, was a graduate student in Genetics at Iowa State University, Ames, IA 50011
| | - Dan Nonneman
- Joshua T. Selsby, PhD, and Jason W. Ross, PhD are associate professors of Animal Science at Iowa State University, Ames, IA 50011. Dan Nonneman, PhD, is a research molecular biologist at the USDA, ARS, U.S. Meat Animal Research Center, Clay Center, NE 68933. Katrin Hollinger, PhD, was a graduate student in Genetics at Iowa State University, Ames, IA 50011
| | - Katrin Hollinger
- Joshua T. Selsby, PhD, and Jason W. Ross, PhD are associate professors of Animal Science at Iowa State University, Ames, IA 50011. Dan Nonneman, PhD, is a research molecular biologist at the USDA, ARS, U.S. Meat Animal Research Center, Clay Center, NE 68933. Katrin Hollinger, PhD, was a graduate student in Genetics at Iowa State University, Ames, IA 50011
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Baratchi S, Almazi JG, Darby W, Tovar-Lopez FJ, Mitchell A, McIntyre P. Shear stress mediates exocytosis of functional TRPV4 channels in endothelial cells. Cell Mol Life Sci 2016; 73:649-66. [PMID: 26289129 PMCID: PMC11108432 DOI: 10.1007/s00018-015-2018-8] [Citation(s) in RCA: 57] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2015] [Revised: 07/25/2015] [Accepted: 08/06/2015] [Indexed: 02/07/2023]
Abstract
Mechanosensitive ion channels are implicated in the biology of touch, pain, hearing and vascular reactivity; however, the identity of these ion channels and the molecular basis of their activation is poorly understood. We previously found that transient receptor potential vanilloid 4 (TRPV4) is a receptor operated ion channel that is sensitised and activated by mechanical stress. Here, we investigated the effects of mechanical stimulation on TRPV4 localisation and activation in native and recombinant TRPV4-expressing cells. We used a combination of total internal reflection fluorescence microscopy, cell surface biotinylation assay and Ca(2+) imaging with laser scanning confocal microscope to show that TRPV4 is expressed in primary vascular endothelial cells and that shear stress sensitises the response of TRPV4 to its agonist, GSK1016790A. The sensitisation was attributed to the recruitment of intracellular pools of TRPV4 to the plasma membrane, through the clathrin and dynamin-mediated exocytosis. The translocation was dependent on ILK/Akt signalling pathway, release of Ca(2+) from intracellular stores and we demonstrated that shear stress stimulated phosphorylation of TRPV4 at tyrosine Y110. Our findings implicate calcium-sensitive TRPV4 translocation in the regulation of endothelial responses to mechanical stimulation.
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Affiliation(s)
- Sara Baratchi
- School of Medical Sciences and Health Innovations Research Institute, RMIT University, Melbourne, VIC, 3083, Australia
| | - Juhura G Almazi
- School of Medical Sciences and Health Innovations Research Institute, RMIT University, Melbourne, VIC, 3083, Australia
| | - William Darby
- School of Medical Sciences and Health Innovations Research Institute, RMIT University, Melbourne, VIC, 3083, Australia
| | - Francisco J Tovar-Lopez
- School of Electrical and Computer Engineering, RMIT University, Melbourne, VIC, 3001, Australia
| | - Arnan Mitchell
- School of Electrical and Computer Engineering, RMIT University, Melbourne, VIC, 3001, Australia
| | - Peter McIntyre
- School of Medical Sciences and Health Innovations Research Institute, RMIT University, Melbourne, VIC, 3083, Australia.
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15
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Kurth F, Franco-Obregón A, Casarosa M, Küster SK, Wuertz-Kozak K, Dittrich PS. Transient receptor potential vanilloid 2-mediated shear-stress responses in C2C12 myoblasts are regulated by serum and extracellular matrix. FASEB J 2015. [PMID: 26207028 DOI: 10.1096/fj.15-275396] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
The developmental sensitivity of skeletal muscle to mechanical forces is unparalleled in other tissues. Calcium entry via reputedly mechanosensitive transient receptor potential (TRP) channel classes has been shown to play an essential role in both the early proliferative stage and subsequent differentiation of skeletal muscle myoblasts, particularly TRP canonical (TRPC) 1 and TRP vanilloid (TRPV) 2. Here we show that C2C12 murine myoblasts respond to fluid flow-induced shear stress with increments in cytosolic calcium that are largely initiated by the mechanosensitive opening of TRPV2 channels. Response to fluid flow was augmented by growth in low extracellular serum concentration (5 vs. 20% fetal bovine serum) by greater than 9-fold and at 18 h in culture, coincident with the greatest TRPV2 channel expression under identical conditions (P < 0.02). Fluid flow responses were also enhanced by substrate functionalization with laminin, rather than with fibronectin, agreeing with previous findings that the gating of TRPV2 is facilitated by laminin. Fluid flow-induced calcium increments were blocked by ruthenium red (27%) and SKF-96365 (38%), whereas they were unaltered by 2-aminoethoxydiphenyl borate, further corroborating that TRPV2 channels play a predominant role in fluid flow mechanosensitivity over that of TRPC1 and TRP melastatin (TRPM) 7.
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Affiliation(s)
- Felix Kurth
- *Department of Biosystems and Science Engineering and Institute for Biomechanics, Eidgenössische Technische Hochschule Zürich, Switzerland; Department of Surgery, Yong Loo Lin School of Medicine, and Department of Physiology, National University of Singapore, Singapore; and National University Hospital Sports Centre, Singapore
| | - Alfredo Franco-Obregón
- *Department of Biosystems and Science Engineering and Institute for Biomechanics, Eidgenössische Technische Hochschule Zürich, Switzerland; Department of Surgery, Yong Loo Lin School of Medicine, and Department of Physiology, National University of Singapore, Singapore; and National University Hospital Sports Centre, Singapore
| | - Marco Casarosa
- *Department of Biosystems and Science Engineering and Institute for Biomechanics, Eidgenössische Technische Hochschule Zürich, Switzerland; Department of Surgery, Yong Loo Lin School of Medicine, and Department of Physiology, National University of Singapore, Singapore; and National University Hospital Sports Centre, Singapore
| | - Simon K Küster
- *Department of Biosystems and Science Engineering and Institute for Biomechanics, Eidgenössische Technische Hochschule Zürich, Switzerland; Department of Surgery, Yong Loo Lin School of Medicine, and Department of Physiology, National University of Singapore, Singapore; and National University Hospital Sports Centre, Singapore
| | - Karin Wuertz-Kozak
- *Department of Biosystems and Science Engineering and Institute for Biomechanics, Eidgenössische Technische Hochschule Zürich, Switzerland; Department of Surgery, Yong Loo Lin School of Medicine, and Department of Physiology, National University of Singapore, Singapore; and National University Hospital Sports Centre, Singapore
| | - Petra S Dittrich
- *Department of Biosystems and Science Engineering and Institute for Biomechanics, Eidgenössische Technische Hochschule Zürich, Switzerland; Department of Surgery, Yong Loo Lin School of Medicine, and Department of Physiology, National University of Singapore, Singapore; and National University Hospital Sports Centre, Singapore
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16
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Tsai TT, Cheng CM, Chen CF, Lai PL. Mechanotransduction in intervertebral discs. J Cell Mol Med 2014; 18:2351-60. [PMID: 25267492 PMCID: PMC4302640 DOI: 10.1111/jcmm.12377] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2014] [Accepted: 07/14/2014] [Indexed: 11/28/2022] Open
Abstract
Mechanotransduction plays a critical role in intracellular functioning—it allows cells to translate external physical forces into internal biochemical activities, thereby affecting processes ranging from proliferation and apoptosis to gene expression and protein synthesis in a complex web of interactions and reactions. Accordingly, aberrant mechanotransduction can either lead to, or be a result of, a variety of diseases or degenerative states. In this review, we provide an overview of mechanotransduction in the context of intervertebral discs, with a focus on the latest methods of investigating mechanotransduction and the most recent findings regarding the means and effects of mechanotransduction in healthy and degenerative discs. We also provide some discussion of potential directions for future research and treatments.
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Affiliation(s)
- Tsung-Ting Tsai
- Department of Orthopaedic Surgery, Spine Section, Chang Gung Memorial Hospital and Chang Gung University College of Medicine, Taoyuan, Taiwan
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17
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Mijares A, Altamirano F, Kolster J, Adams JA, López JR. Age-dependent changes in diastolic Ca(2+) and Na(+) concentrations in dystrophic cardiomyopathy: Role of Ca(2+) entry and IP3. Biochem Biophys Res Commun 2014; 452:1054-9. [PMID: 25242522 DOI: 10.1016/j.bbrc.2014.09.045] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/03/2014] [Accepted: 09/11/2014] [Indexed: 01/01/2023]
Abstract
Duchenne muscular dystrophy (DMD) is a lethal X-inherited disease caused by dystrophin deficiency. Besides the relatively well characterized skeletal muscle degenerative processes, DMD is also associated with a dilated cardiomyopathy that leads to progressive heart failure at the end of the second decade. The aim of the present study was to characterize the diastolic Ca(2+) concentration ([Ca(2+)]d) and diastolic Na(+) concentration ([Na(+)]d) abnormalities in cardiomyocytes isolated from 3-, 6-, 9-, and 12-month old mdx mice using ion-selective microelectrodes. In addition, the contributions of gadolinium (Gd(3+))-sensitive Ca(2+) entry and inositol triphosphate (IP3) signaling pathways in abnormal [Ca(2+)]d and [Na(+)]d were investigated. Our results showed an age-dependent increase in both [Ca(2+)]d and [Na(+)]d in dystrophic cardiomyocytes compared to those isolated from age-matched wt mice. Gd(3+) treatment significantly reduced both [Ca(2+)]d and [Na(+)]d at all ages. In addition, blockade of the IP3-pathway with either U-73122 or xestospongin C significantly reduced ion concentrations in dystrophic cardiomyocytes. Co-treatment with U-73122 and Gd(3+) normalized both [Ca(2+)]d and [Na(+)]d at all ages in dystrophic cardiomyocytes. These data showed that loss of dystrophin in mdx cardiomyocytes produced an age-dependent intracellular Ca(2+) and Na(+) overload mediated at least in part by enhanced Ca(2+) entry through Gd(3+) sensitive transient receptor potential channels (TRPC), and by IP3 receptors.
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Affiliation(s)
- Alfredo Mijares
- Instituto Venezolano de Investigaciones Científicas, Centro de Biofísica y Bioquímica, Caracas, Venezuela
| | - Francisco Altamirano
- Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA 95616, USA
| | - Juan Kolster
- Centro de Investigaciones Biomédicas, México D.F., Mexico
| | - José A Adams
- Division of Neonatology, Mount Sinai Medical Center, Miami, FL 33140, USA
| | - José R López
- Instituto Venezolano de Investigaciones Científicas, Centro de Biofísica y Bioquímica, Caracas, Venezuela; Department of Molecular Biosciences, School of Veterinary Medicine, University of California, Davis, CA 95616, USA.
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18
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Brault JJ, Pizzimenti NM, Dentel JN, Wiseman RW. Selective inhibition of ATPase activity during contraction alters the activation of p38 MAP kinase isoforms in skeletal muscle. J Cell Biochem 2014; 114:1445-55. [PMID: 23296747 DOI: 10.1002/jcb.24486] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Accepted: 12/18/2012] [Indexed: 11/10/2022]
Abstract
Muscle contractions strongly activate p38 MAP kinases, but the precise contraction-associated sarcoplasmic event(s) (e.g., force production, energetic demands, and/or calcium cycling) that activate these kinases are still unclear. We tested the hypothesis that during contraction the phosphorylation of p38 isoforms is sensitive to the increase in ATP demand relative to ATP supply. Energetic demands were inhibited using N-benzyl-p-toluene sulphonamide (BTS, type II actomyosin) and cyclopiazonic acid (CPA, SERCA). Extensor digitorum longus muscles from Swiss Webster mice were incubated in Ringer's solution (37°C) with or without inhibitors and then stimulated at 10 Hz for 15 min. Muscles were immediately freeze-clamped for metabolite and Western blot analysis. BTS and BTS + CPA treatment decreased force production by 85%, as measured by the tension time integral, while CPA alone potentiated force by 310%. In control muscles, contractions resulted in a 73% loss of ATP content and a concomitant sevenfold increase in IMP content, a measure of sustained energetic imbalance. BTS or CPA treatment lessened the loss of ATP, but BTS + CPA treatment completely eliminated the energetic imbalance since ATP and IMP levels were nearly equal to those of non-stimulated muscles. The independent inhibition of cytosolic ATPase activities had no effect on contraction-induced p38 MAPK phosphorylation, but combined treatment prevented the increase in phosphorylation of the γ isoform while the α/β isoforms unaffected. These observations suggest that an energetic signal may trigger phosphorylation of the p38γ isoform and also may explain how contractions differentially activate signaling pathways.
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Affiliation(s)
- Jeffrey J Brault
- Department of Kinesiology, East Carolina University, Greenville, North Carolina, USA
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19
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Tan N, Lansman JB. Utrophin regulates modal gating of mechanosensitive ion channels in dystrophic skeletal muscle. J Physiol 2014; 592:3303-23. [PMID: 24879867 DOI: 10.1113/jphysiol.2014.274332] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022] Open
Abstract
Dystrophin is a large, submembrane cytoskeletal protein, absence of which causes Duchenne muscular dystrophy. Utrophin is a dystrophin homologue found in both muscle and brain whose physiological function is unknown. Recordings of single-channel activity were made from membrane patches on skeletal muscle from mdx, mdx/utrn(+/-) heterozygotes and mdx/utrn(-/-) double knockout mice to investigate the role of these cytoskeletal proteins in mechanosensitive (MS) channel gating. We find complex, gene dose-dependent effects of utrophin depletion in dystrophin-deficient mdx muscle: (1) increased MS channel open probability, (2) a shift of MS channel gating to larger pressures, (3) appearance of modal gating of MS channels and small conductance channels and (4) expression of large conductance MS channels. We suggest a physical model in which utrophin acts as a scaffolding protein that stabilizes lipid microdomains and clusters MS channel subunits. Depletion of utrophin disrupts domain composition in a manner that favours open channel area expansion, as well as allowing diffusion and aggregation of additional MS channel subunits.
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Affiliation(s)
- Nhi Tan
- Department of Cellular and Molecular Pharmacology, School of Medicine, University of California, San Francisco, San Francisco, CA, 94143-0450, USA
| | - Jeffry B Lansman
- Department of Cellular and Molecular Pharmacology, School of Medicine, University of California, San Francisco, San Francisco, CA, 94143-0450, USA
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20
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Martinac B. The ion channels to cytoskeleton connection as potential mechanism of mechanosensitivity. BIOCHIMICA ET BIOPHYSICA ACTA-BIOMEMBRANES 2013; 1838:682-91. [PMID: 23886913 DOI: 10.1016/j.bbamem.2013.07.015] [Citation(s) in RCA: 89] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2013] [Revised: 07/05/2013] [Accepted: 07/15/2013] [Indexed: 01/07/2023]
Abstract
As biological force-sensing systems mechanosensitive (MS) ion channels present the best example of coupling molecular dynamics of membrane proteins to the mechanics of the surrounding cell membrane. In animal cells MS channels have over the past two decades been very much in focus of mechanotransduction research. In recent years this helped to raise awareness of basic and medical researchers about the role that abnormal MS channels may play in the pathophysiology of diseases, such as cardiac hypertrophy, atrial fibrillation, muscular dystrophy or polycystic kidney disease. To date a large number of MS channels from organisms of diverse phylogenetic origins have been identified at the molecular level; however, the structure of only few of them has been determined. Although their function has extensively been studied in a great variety of cells and tissues by different experimental approaches it is, with exception of bacterial MS channels, very little known about how these channels sense mechanical force and which cellular components may contribute to their function. By focusing on MS channels found in animal cells this article discusses the ways in which the connections between cytoskeleton and ion channels may contribute to mechanosensory transduction in these cells. This article is part of a Special Issue entitled: Reciprocal influences between cell cytoskeleton and membrane channels, receptors and transporters. This article is part of a Special Issue entitled: Reciprocal influences between cell cytoskeleton and membrane channels, receptors and transporters. Guest Editor: Jean Claude Hervé.
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Affiliation(s)
- Boris Martinac
- Victor Chang Cardiac Research Institute, Darlinghurst, NSW 2010, Australia; St Vincent's Clinical School, University of New South Wales, Sydney, NSW 2052, Australia.
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21
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Vasquez I, Tan N, Boonyasampant M, Koppitch KA, Lansman JB. Partial opening and subconductance gating of mechanosensitive ion channels in dystrophic skeletal muscle. J Physiol 2012; 590:6167-85. [PMID: 22966155 PMCID: PMC3530124 DOI: 10.1113/jphysiol.2012.240044] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2012] [Accepted: 09/03/2012] [Indexed: 12/31/2022] Open
Abstract
We recorded the activity of single mechanosensitive (MS) ion channels in skeletal muscle from the mdx mouse, a deletion mutant that lacks the cytoskeletal protein, dystrophin. Experiments were designed to examine the influence of dystrophin, a major component of skeletal muscle costameres, on the behaviour of single MS channels. In the majority of recordings from cell-attached patches, MS channels have a conductance of ∼23 pS. Recordings from some patches, however, showed a smaller conductance channel of ∼7-14 pS. Large and small conductance channels were detected in a single patch and showed serial, non-random gating, suggesting different opening levels of a single channel. Analysis of the distribution of current amplitudes within the open channel showed MS channels fluctuate between subconductance levels. MS channels in dystrophic muscle spend ∼60% of the time at smaller subconductance levels, often failing to reach the fully open level. Applying pressure to the membrane of mdx fibres increases in a graded manner occupancy of the fully open state, while reducing occupancy of subconductance levels. Recordings also show partial openings of MS channels in both wild-type and mdx muscle that fail to reach the fully open state. Partial openings occur at a higher frequency in mdx muscle and reflect occupancy of subconductance levels seen during complete activations. In muscle from mdx/utrn(-/-) double knockout mice, MS channels also spend more time at subconductance levels than the fully open state. Conductance variability of MS channels may represent gating of a heteromeric protein composed of different channel subunits. The results also show that partial opening and prolonged burst duration are distinct mechanisms that contribute to excess Ca(2+) entry in dystrophic muscle.
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Affiliation(s)
- Ivan Vasquez
- Department of Cellular & Molecular Pharmacology, School of Medicine, University of California, San Francisco, CA 94143-0450, USA
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Gray SK, McGee-Lawrence ME, Sanders JL, Condon KW, Tsai CJ, Donahue SW. Black bear parathyroid hormone has greater anabolic effects on trabecular bone in dystrophin-deficient mice than in wild type mice. Bone 2012; 51:578-85. [PMID: 22584007 PMCID: PMC3412940 DOI: 10.1016/j.bone.2012.05.003] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/13/2012] [Revised: 05/03/2012] [Accepted: 05/04/2012] [Indexed: 12/12/2022]
Abstract
Duchenne muscular dystrophy (DMD) is an X-linked neuromuscular disease that has deleterious consequences in muscle and bone, leading to decreased mobility, progressive osteoporosis, and premature death. Patients with DMD experience a higher-than-average fracture rate, particularly in the proximal and distal femur and proximal tibia. The dystrophin-deficient mdx mouse is a model of DMD that demonstrates muscle degeneration and fibrosis and osteoporosis. Parathyroid hormone, an effective anabolic agent for post-menopausal and glucocorticoid-induced osteoporosis, has not been explored for DMD. Black bear parathyroid hormone (bbPTH) has been implicated in the maintenance of bone properties during extended periods of disuse (hibernation). We cloned bbPTH and found 9 amino acid residue differences from human PTH. Apoptosis was mitigated and cAMP was activated by bbPTH in osteoblast cultures. We administered 28nmol/kg of bbPTH 1-84 to 4-week old male mdx and wild type mice via daily (5×/week) subcutaneous injection for 6 weeks. Vehicle-treated mdx mice had 44% lower trabecular bone volume fraction than wild type mice. No changes were found in femoral cortical bone geometry or mechanical properties with bbPTH treatment in wild type mice, and only medio-lateral moment of inertia changed with bbPTH treatment in mdx femurs. However, μCT analyses of the trabecular regions of the distal femur and proximal tibia showed marked increases in bone volume fraction with bbPTH treatment, with a greater anabolic response (7-fold increase) in mdx mice than wild type mice (2-fold increase). Trabecular number increased in mdx long bone, but not wild type bone. Additionally, greater osteoblast area and decreased osteoclast area were observed with bbPTH treatment in mdx mice. The heightened response to PTH in mdx bone compared to wild type suggests a link between dystrophin deficiency, altered calcium signaling, and bone. These findings support further investigation of PTH as an anabolic treatment for DMD-induced osteoporosis.
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Affiliation(s)
- Sarah K Gray
- Michigan Tech University, Dept. of Biomedical Engineering, 309 M&M Bldg., 1400 Townsend Dr., Houghton, MI 49931, USA
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Ho TC, Horn NA, Huynh T, Kelava L, Lansman JB. Evidence TRPV4 contributes to mechanosensitive ion channels in mouse skeletal muscle fibers. Channels (Austin) 2012; 6:246-54. [PMID: 22785252 DOI: 10.4161/chan.20719] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
We recorded the activity of single mechanosensitive (MS) ion channels from membrane patches on single muscle fibers isolated from mice. We investigated the actions of various TRP (transient receptor potential) channel blockers on MS channel activity. 2-aminoethoxydiphenyl borate (2-APB) neither inhibited nor facilitated single channel activity at submillimolar concentrations. The absence of an effect of 2-APB indicates MS channels are not composed purely of TRPC or TRPV1, 2 or 3 proteins. Exposing patches to 1-oleolyl-2-acetyl-sn-glycerol (OAG), a potent activator of TRPC channels, also had no effect on MS channel activity. In addition, flufenamic acid and spermidine had no effect on the activity of single MS channels. By contrast, SKF-96365 and ruthenium red blocked single-channel currents at micromolar concentrations. SKF-96365 produced a rapid block of the open channel current. The blocking rate depended linearly on blocker concentration, while the unblocking rate was independent of concentration, consistent with a simple model of open channel block. A fit to the concentration-dependence of block gave k(on) = 13 x 10 ( 6) M (-1) s (-1) and k(off) = 1609 sec (-1) with K(D) = ~124 µM. Block by ruthenium red was complex, involving both reduction of the amplitude of the single-channel current and increased occupancy of subconductance levels. The reduction in current amplitude with increasing concentration of ruthenium red gave a K(D) = ~49 µM. The high sensitivity of MS channels to block by ruthenium red suggests MS channels in skeletal muscle contain TRPV subunits. Recordings from skeletal muscle isolated from TRPV4 knockout mice failed to show MS channel activity, consistent with a contribution of TRPV4. In addition, exposure to hypo-osmotic solutions increases opening of MS channels in muscle. Our results provide evidence TRPV4 contributes to MS channels in skeletal muscle.
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Affiliation(s)
- Tiffany C Ho
- Department of Cellular and Molecular Pharmacology, School of Medicine, University of California, San Francisco, San Francisco, CA, USA
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Weber MA, Nagel AM, Wolf MB, Jurkat-Rott K, Kauczor HU, Semmler W, Lehmann-Horn F. Permanent muscular sodium overload and persistent muscle edema in Duchenne muscular dystrophy: a possible contributor of progressive muscle degeneration. J Neurol 2012; 259:2385-92. [PMID: 22544297 DOI: 10.1007/s00415-012-6512-8] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2012] [Revised: 04/02/2012] [Accepted: 04/03/2012] [Indexed: 11/29/2022]
Abstract
To assess the presence and persistence of muscular edema and increased myoplasmic sodium (Na(+)) concentration in Duchenne muscular dystrophy (DMD). We examined eight DMD patients (mean age 9.5 ± 5.4 years) and eight volunteers (mean age 9.5 ± 3.2 years) with 3-tesla proton ((1)H) and (23)Na density-adapted 3D-radial MR sequences. Seven DMD patients were re-examined about 7 months later without change of therapy. The eighth DMD patient was re-examined after 5 and 11 months under medication with eplerenone. We quantified muscle edema on STIR images with background noise as reference and fatty degeneration on T1-weighted images using subcutaneous fat as reference. Na(+) was quantified by a muscular tissue Na(+) concentration (TSC) sequence employing a reference containing 51.3 mM Na(+) with 5 % agarose. With an inversion-recovery (IR) sequence, we determined mainly the myoplasmic Na(+). The normalized muscular (23)Na IR signal intensity was higher in DMD than in volunteers (n = 8, 0.75 ± 0.07 vs. 0.50 ± 0.05, p < 0.001) and persisted at second measurement (n = 7, 1st 0.75 ± 0.07, 2nd 0.73 ± 0.06, p = 0.50). When compared to volunteers (25.6 ± 2.0 mmol/l), TSC was markedly increased in DMD (38.0 ± 5.9 mmol/l, p < 0.001) and remained constant (n = 7, 1st 37.9 ± 6.4 mmol/l, 2nd 37.0 ± 4.0 mmol/l, p = 0.49). Muscular edema (15.6 ± 3.5 vs. 6.9 ± 0.7, p < 0.001) and fat content (0.48 ± 0.08 vs. 0.38 ± 0.01, p = 0.003) were elevated in DMD when compared to volunteers. This could also be confirmed during follow-up (n = 7, p = 0.91, p = 0.12). Eplerenone slightly improved muscle strength and reduced muscular sodium and edema. The permanent muscular Na(+) overload in all DMD patients is likely osmotically relevant and responsible for the persisting, mainly intracellular muscle edema that may contribute to the progressive muscle degeneration.
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Affiliation(s)
- M-A Weber
- Department of Diagnostic and Interventional Radiology, University Hospital of Heidelberg, Im Neuenheimer Feld 110, 69120, Heidelberg, Germany.
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Schaffhauser DF, Andrini O, Ghezzi C, Forster IC, Franco-Obregón A, Egli M, Dittrich PS. Microfluidic platform for electrophysiological studies on Xenopus laevis oocytes under varying gravity levels. LAB ON A CHIP 2011; 11:3471-3478. [PMID: 21870012 DOI: 10.1039/c0lc00729c] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/31/2023]
Abstract
Voltage clamp measurements reveal important insights into the activity of membrane ion channels. While conventional voltage clamp systems are available for laboratory studies, these instruments are generally unsuitable for more rugged operating environments. In this study, we present a non-invasive microfluidic voltage clamp system developed for the use under varying gravity levels. The core component is a multilayer microfluidic device that provides an immobilisation site for Xenopus laevis oocytes on an intermediate layer, and fluid and electrical connections from either side of the cell. The configuration that we term the asymmetrical transoocyte voltage clamp (ATOVC) also permits electrical access to the cytosol of the oocyte without physical introduction of electrodes by permeabilisation of a large region of the oocyte membrane so that a defined membrane patch can be voltage clamped. The constant low level air pressure applied to the oocyte ensures stable immobilisation, which is essential for keeping the leak resistance constant even under varying gravitational forces. The ease of oocyte mounting and immobilisation combined with the robustness and complete enclosure of the fluidics system allow the use of the ATOVC under extreme environmental conditions, without the need for intervention by a human operator. Results for oocytes over-expressing the epithelial sodium channel (ENaC) obtained under laboratory conditions as well as under conditions of micro- and hypergravity demonstrate the high reproducibility and stability of the ATOVC system under distinct mechanical scenarios.
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Markert CD, Ambrosio F, Call JA, Grange RW. Exercise and Duchenne muscular dystrophy: toward evidence-based exercise prescription. Muscle Nerve 2011; 43:464-78. [PMID: 21404285 DOI: 10.1002/mus.21987] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
To develop a rational framework for answering questions about the role of exercise in Duchenne muscular dystrophy (DMD), we focused on five pathophysiological mechanisms and offer brief hypotheses regarding how exercise may beneficially modulate pertinent cellular and molecular pathways. We aimed to provide an integrative overview of mechanisms of DMD pathology that may improve or worsen as a result of exercise. We also sought to stimulate discussion of what outcomes/dependent variables most appropriately measure these mechanisms, with the purpose of defining criteria for well-designed, controlled studies of exercise in DMD. The five mechanisms include pathways that are both intrinsic and extrinsic to the diseased muscle cells.
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Affiliation(s)
- Chad D Markert
- Wake Forest Institute for Regenerative Medicine, Medical Center Boulevard, Winston-Salem, North Carolina 27157, USA.
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Stiber JA, Rosenberg PB. The role of store-operated calcium influx in skeletal muscle signaling. Cell Calcium 2010; 49:341-9. [PMID: 21176846 DOI: 10.1016/j.ceca.2010.11.012] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2010] [Accepted: 11/29/2010] [Indexed: 11/29/2022]
Abstract
In cardiac and skeletal muscle Ca(2+) release from intracellular stores triggers actomyosin cross-bridge formation and the generation of contractile force. In the face of large fluctuations of intracellular calcium ([Ca(2+)](i)) that occur with contractile activity, myocytes are able to sense and respond to changes in workload and patterns of activation through calcium signaling pathways which modulate gene expression and cellular metabolism. Store-operated calcium influx has emerged as a mechanism by which calcium signaling pathways are activated in order to respond to the changing demands of the myocyte. Abnormalities of store-operated calcium influx may contribute to maladaptive muscle remodeling in multiple disease states. The importance of store-operated calcium influx in muscle is confirmed in mice lacking STIM1 which die perinatally and in patients with mutations on STIM1 or Orai1 who exhibit a myopathy exhibited by hypotonia. In this review, we consider the role of store-operated Ca(2+) entry into skeletal muscle as a critical mediator of Ca(2+) dependent gene expression and how alterations in Ca(2+) influx may influence muscle development and disease.
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Affiliation(s)
- Jonathan A Stiber
- Department of Medicine, Duke University Medical Center, Durham, NC 27710, United States
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Rowell J, Koitabashi N, Kass DA. TRP-ing up heart and vessels: canonical transient receptor potential channels and cardiovascular disease. J Cardiovasc Transl Res 2010; 3:516-24. [PMID: 20652467 DOI: 10.1007/s12265-010-9208-4] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2010] [Accepted: 06/28/2010] [Indexed: 12/24/2022]
Abstract
Transient receptor potential channels are a large superfamily of non-selective and non-voltage-gated ion channels that convey signaling information linked to a broad range of sensory inputs. In the cardiovascular system, the canonical transient receptor potential (TRPC) family has been particularly found to play a role in vascular and cardiac disease, responding to neurohormonal and mechanical load stimulation. TRPC1, TRPC3, and TRPC6 are often upregulated in models of cardiovascular disease, and their inhibition ameliorates the associated pathophysiology. Studies in gene deletion models and overexpression models of wild-type and dominant-negative proteins supports a direct role of these channels, which likely act together as heterotetramers to influence signaling. Recent evidence has further revealed the importance of protein kinase G phosphorylation as a mechanism to suppress TRPC6 channel current and dependent signaling in vascular and cardiac myocytes. This suggests a novel mechanism underlying benefits of drugs such as sildenafil, a phosphodiesterase type 5 inhibitor, nitrates, and atrial natriuretic peptides. This review describes new evidence supporting a pathophysiologic role of these three TRPC channels, and the potential utility of inhibition strategies to treat cardiovascular disease.
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Affiliation(s)
- Janelle Rowell
- The Division of Cardiology, Department of Medicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
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29
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Formigli L, Sassoli C, Squecco R, Bini F, Martinesi M, Chellini F, Luciani G, Sbrana F, Zecchi-Orlandini S, Francini F, Meacci E. Regulation of transient receptor potential canonical channel 1 (TRPC1) by sphingosine 1-phosphate in C2C12 myoblasts and its relevance for a role of mechanotransduction in skeletal muscle differentiation. J Cell Sci 2009; 122:1322-33. [DOI: 10.1242/jcs.035402] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023] Open
Abstract
Transient receptor potential canonical (TRPC) channels provide cation and Ca2+ entry pathways, which have important regulatory roles in many physio-pathological processes, including muscle dystrophy. However, the mechanisms of activation of these channels remain poorly understood. Using siRNA, we provide the first experimental evidence that TRPC channel 1 (TRPC1), besides acting as a store-operated channel, represents an essential component of stretch-activated channels in C2C12 skeletal myoblasts, as assayed by whole-cell patch-clamp and atomic force microscopic pulling. The channel's activity and stretch-induced Ca2+ influx were modulated by sphingosine 1-phosphate (S1P), a bioactive lipid involved in satellite cell biology and tissue regeneration. We also found that TRPC1 was functionally assembled in lipid rafts, as shown by the fact that cholesterol depletion resulted in the reduction of transmembrane ion current and conductance. Association between TRPC1 and lipid rafts was increased by formation of stress fibres, which was elicited by S1P and abolished by treatment with the actin-disrupting dihydrocytochalasin B, suggesting a role for cytoskeleton in TRPC1 membrane recruitment. Moreover, TRPC1 expression was significantly upregulated during myogenesis, especially in the presence of S1P, implicating a crucial role for TRPC1 in myoblast differentiation. Collectively, these findings may offer new tools for understanding the role of TRPC1 and sphingolipid signalling in skeletal muscle regeneration and provide new therapeutic approaches for skeletal muscle disorders.
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Affiliation(s)
- Lucia Formigli
- Department of Anatomy, Histology and Forensic Medicine, University of Florence, Florence, Italy
- Interuniversity Institute of Miology (IIM), University of Florence, Florence, Italy
| | - Chiara Sassoli
- Department of Anatomy, Histology and Forensic Medicine, University of Florence, Florence, Italy
- Interuniversity Institute of Miology (IIM), University of Florence, Florence, Italy
| | - Roberta Squecco
- Department of Physiological Sciences, University of Florence, Florence, Italy
- Interuniversity Institute of Miology (IIM), University of Florence, Florence, Italy
| | - Francesca Bini
- Department of Biochemical Sciences, University of Florence, Florence, Italy
| | - Maria Martinesi
- Department of Biochemical Sciences, University of Florence, Florence, Italy
| | - Flaminia Chellini
- Department of Anatomy, Histology and Forensic Medicine, University of Florence, Florence, Italy
| | - Giorgia Luciani
- Department of Physiological Sciences, University of Florence, Florence, Italy
| | - Francesca Sbrana
- C.S.D.C. Department of Physics, University of Florence, Florence, Italy
| | - Sandra Zecchi-Orlandini
- Department of Anatomy, Histology and Forensic Medicine, University of Florence, Florence, Italy
- Interuniversity Institute of Miology (IIM), University of Florence, Florence, Italy
| | - Fabio Francini
- Department of Physiological Sciences, University of Florence, Florence, Italy
- Interuniversity Institute of Miology (IIM), University of Florence, Florence, Italy
| | - Elisabetta Meacci
- Department of Biochemical Sciences, University of Florence, Florence, Italy
- Interuniversity Institute of Miology (IIM), University of Florence, Florence, Italy
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Xiong Y, Zhou Y, Jarrett HW. Dystrophin glycoprotein complex-associated Gbetagamma subunits activate phosphatidylinositol-3-kinase/Akt signaling in skeletal muscle in a laminin-dependent manner. J Cell Physiol 2009; 219:402-14. [PMID: 19117013 DOI: 10.1002/jcp.21684] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
Previously, we showed that laminin-binding to the dystrophin glycoprotein complex (DGC) of skeletal muscle causes a heterotrimeric G-protein (Galphabetagamma) to bind, changing the activation state of the Gsalpha subunit. Others have shown that laminin-binding to the DGC also leads to Akt activation. Gbetagamma, released when Gsalpha is activated, is known to bind phosphatidylinositol-3-kinase (PI3K), which activates Akt in other cells. Here, we investigate whether muscle Akt activation results from Gbetagamma, using immunoprecipitation and immunoblotting, and purified Gbetagamma. In the presence of laminin, PI3K-binding to the DGC increases and Akt becomes phosphorylated and activated (pAkt), and glycogen synthase kinase is phosphorylated. Antibodies, which specifically block laminin-binding to alpha-dystroglycan, prevent PI3K-binding to the DGC. Purified bovine brain Gbetagamma also caused PI3K and Akt activation. These results show that DGC-Gbetagamma is binding PI3K and activating pAkt in a laminin-dependent manner. Mdx mice, which have greatly diminished amounts of DGC proteins, display elevated pAkt signaling and increased expression of integrin beta1 compared to normal muscle. This integrin binds laminin, Gbetagamma, and PI3K. Collectively, these suggest that PI3K is an important target for the Gbetagamma, which normally binds to DGC syntrophin, and activates PI3K/Akt signaling. Disruption of the DGC in mdx mouse is causing dis-regulation of the laminin-DGC-Gbetagamma-PI3K-Akt signaling and is likely to be important to the pathogenesis of muscular dystrophy. Upregulating integrin beta1 expression and activating the PI3K/Akt pathway in muscular dystrophy may partially compensate for the loss of the DGC. The results suggest new therapeutic approaches to muscle disease.
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Affiliation(s)
- Yongmin Xiong
- Key Laboratory of Environment and Genes Related to Disease, Department of Public Health, Xi'an Jiaotong University College of Medicine, Xi'an, Shaanxi Province, People's Republic of China
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Abstract
Cells sense their physical surroundings through mechanotransduction - that is, by translating mechanical forces and deformations into biochemical signals such as changes in intracellular calcium concentration or by activating diverse signalling pathways. In turn, these signals can adjust cellular and extracellular structure. This mechanosensitive feedback modulates cellular functions as diverse as migration, proliferation, differentiation and apoptosis, and is crucial for organ development and homeostasis. Consequently, defects in mechanotransduction - often caused by mutations or misregulation of proteins that disturb cellular or extracellular mechanics - are implicated in the development of various diseases, ranging from muscular dystrophies and cardiomyopathies to cancer progression and metastasis.
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Wu PI, Minisini S, Edelman ER. Intramuscular drug transport under mechanical loading: resonance between tissue function and uptake. J Control Release 2009; 136:99-109. [PMID: 19331855 DOI: 10.1016/j.jconrel.2009.01.016] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2008] [Revised: 01/09/2009] [Accepted: 01/25/2009] [Indexed: 11/29/2022]
Abstract
Dynamic architecture and motion in mechanically active target tissues can influence the pharmacokinetics of locally delivered agents. Drug transport in skeletal muscle under controlled mechanical loads was investigated. Static (0-20%) and cyclic (+/-2.5% amplitude, 0-20% mean, 1-3 Hz) strains and electrically paced isometric contractions (0.1-3 Hz, 0% strain) were applied to rat soleus incubated in 1 mM 20 kDa FITC-dextran. Dextran penetration, tissue porosity, and active force-length relationship over 0-20% strain correlated (r=0.9-1.0), and all increased 1.5-fold from baseline at 0% to a maximum at 10% (Lo), demonstrating biologic significance of Lo and impact of fiber size and distribution on function and pharmacokinetics. Overall penetration decreased but relative enhancement of penetration at Lo increased with dextran size (4-150 kDa). Penetration increased linearly (0.084 mm/Hz) with cyclic stretch, demonstrating dispersion. Penetration increased with contraction rate by 1.5-fold from baseline to a maximum at 0.5 Hz, revealing architectural modulation of dispersion. Impact of architecture and dispersion on intramuscular transport was computationally modeled. Mechanical architecture and function underlie intramuscular pharmacokinetics and act in concert to effect resonance between optimal physiologic performance and drug uptake. Therapeutic management of characteristic function in tissue targets may enable a physiologic mechanism for controlled drug transport.
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Affiliation(s)
- Peter I Wu
- Biomedical Engineering Center, Harvard-MIT Division of Health Sciences and Technology, Massachusetts Institute of Technology, E25-438, Cambridge, Massachusetts 02139, USA
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Teichmann MDH, Wegner FV, Fink RHA, Chamberlain JS, Launikonis BS, Martinac B, Friedrich O. Inhibitory control over Ca(2+) sparks via mechanosensitive channels is disrupted in dystrophin deficient muscle but restored by mini-dystrophin expression. PLoS One 2008; 3:e3644. [PMID: 18982068 PMCID: PMC2575405 DOI: 10.1371/journal.pone.0003644] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/18/2008] [Accepted: 10/17/2008] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND In dystrophic skeletal muscle, osmotic stimuli somehow relieve inhibitory control of dihydropyridine receptors (DHPR) on spontaneous sarcoplasmic reticulum elementary Ca(2+) release events (ECRE) in high Ca(2+) external environments. Such 'uncontrolled' Ca(2+) sparks were suggested to act as dystrophic signals. They may be related to mechanosensitive pathways but the mechanisms are elusive. Also, it is not known whether truncated dystrophins can correct the dystrophic disinhibition. METHODOLOGY/PRINCIPAL FINDINGS We recorded ECRE activity in single intact fibers from adult wt, mdx and mini-dystrophin expressing mice (MinD) under resting isotonic conditions and following hyper-/hypo-osmolar external shock using confocal microscopy and imaging techniques. Isotonic ECRE frequencies were small in wt and MinD fibers, but were markedly increased in mdx fibers. Osmotic challenge dramatically increased ECRE activity in mdx fibers. Sustained osmotic challenge induced marked exponential ECRE activity adaptation that was three times faster in mdx compared to wt and MinD fibers. Rising external Ca(2+) concentrations amplified osmotic ECRE responses. The eliminated ECRE suppression in intact osmotically stressed mdx fibers was completely and reversibly resuscitated by streptomycine (200 microM), spider peptide GsMTx-4 (5 microM) and Gd(3+) (20 microM) that block unspecific, specific cationic and Ca(2+) selective mechanosensitive channels (MsC), respectively. ECRE morphology was not substantially altered by membrane stress. During hyperosmotic challenge, membrane potentials were polarised and a putative depolarisation through aberrant MsC negligible excluding direct activation of ECRE through tubular depolarisation. CONCLUSIONS/SIGNIFICANCE Dystrophin suppresses spontaneous ECRE activity by control of mechanosensitive pathways which are suggested to interact with the inhibitory DHPR loop to the ryanodine receptor. MsC-related disinhibition prevails in dystrophic muscle and can be resuscitated by transgenic mini-dystrophin expression. Our results have important implications for the pathophysiology of DMD where abnormal MsC in dystrophic muscle confer disruption of microdomain Ca(2+) homeostasis. MsC blockers should have considerable therapeutic potential if more muscle specific compounds can be found.
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MESH Headings
- Adult
- Animals
- Calcium Channels, L-Type/metabolism
- Calcium Signaling/physiology
- Dystrophin/genetics
- Dystrophin/metabolism
- Humans
- Ion Channels/metabolism
- Mechanotransduction, Cellular/physiology
- Membrane Potentials/physiology
- Mice
- Mice, Inbred C57BL
- Mice, Inbred mdx
- Mice, Transgenic
- Muscle Fibers, Skeletal/cytology
- Muscle Fibers, Skeletal/physiology
- Muscle, Skeletal/cytology
- Muscle, Skeletal/physiology
- Muscle, Skeletal/physiopathology
- Muscular Dystrophy, Duchenne/physiopathology
- Osmotic Pressure
- Ryanodine Receptor Calcium Release Channel/metabolism
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Affiliation(s)
- Martin D. H. Teichmann
- Medical Biophysics, Department of Systems Physiology, Institute of Physiology and Pathophysiology, Ruprecht-Karls-University, Heidelberg, Germany
| | - Frederic v. Wegner
- Medical Biophysics, Department of Systems Physiology, Institute of Physiology and Pathophysiology, Ruprecht-Karls-University, Heidelberg, Germany
| | - Rainer H. A. Fink
- Medical Biophysics, Department of Systems Physiology, Institute of Physiology and Pathophysiology, Ruprecht-Karls-University, Heidelberg, Germany
| | - Jeffrey S. Chamberlain
- Department of Neurology, University of Washington, Seattle, Washington, United States of America
| | - Bradley S. Launikonis
- School of Biomedical Sciences, University of Queensland, Brisbane, Queensland, Australia
| | - Boris Martinac
- School of Biomedical Sciences, University of Queensland, Brisbane, Queensland, Australia
| | - Oliver Friedrich
- Medical Biophysics, Department of Systems Physiology, Institute of Physiology and Pathophysiology, Ruprecht-Karls-University, Heidelberg, Germany
- School of Biomedical Sciences, University of Queensland, Brisbane, Queensland, Australia
- * E-mail:
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Sappington RM, Sidorova T, Long DJ, Calkins DJ. TRPV1: contribution to retinal ganglion cell apoptosis and increased intracellular Ca2+ with exposure to hydrostatic pressure. Invest Ophthalmol Vis Sci 2008; 50:717-28. [PMID: 18952924 DOI: 10.1167/iovs.08-2321] [Citation(s) in RCA: 151] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023] Open
Abstract
PURPOSE Elevated hydrostatic pressure induces retinal ganglion cell (RGC) apoptosis in culture. The authors investigated whether the transient receptor potential vanilloid 1 (TRPV1) channel, which contributes to pressure sensing and Ca(2+)-dependent cell death in other systems, also contributes to pressure-induced RGC death and whether this contribution involves Ca(2+). METHODS trpv1 mRNA expression in RGCs was probed with the use of PCR and TRPV1 protein localization through immunocytochemistry. Subunit-specific antagonism (iodo-resiniferatoxin) and agonism (capsaicin) were used to probe how TRPV1 activation affects the survival of isolated RGCs at ambient and elevated hydrostatic pressure (+70 mm Hg). Finally, for RGCs under pressure, the authors tested whether EGTA chelation of Ca(2+) improves survival and whether, with the Ca(2+) dye Fluo-4 AM, TRPV1 contributes to increased intracellular Ca(2+). RESULTS RGCs express trpv1 mRNA, with robust TRPV1 protein localization to the cell body and axon. For isolated RGCs under pressure, TRPV1 antagonism increased cell density and reduced apoptosis to ambient levels (P <or= 0.05), whereas for RGCs at ambient pressure, TRPV1 agonism reduced density and increased apoptosis to levels for elevated pressure (P <or= 0.01). Chelation of extracellular Ca(2+) reduced RGC apoptosis at elevated pressure by nearly twofold (P <or= 0.01). Exposure to elevated hydrostatic pressure induced a fourfold increase in RGC intracellular Ca(2+) that was reduced by half with TRPV1 antagonism. Finally, in the DBA/2 mouse model of glaucoma, levels of TRPV1 in RGCs increased with elevated IOP. CONCLUSIONS RGC apoptosis induced by elevated hydrostatic pressure arises substantially through TRPV1, likely through the influx of extracellular Ca(2+).
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Affiliation(s)
- Rebecca M Sappington
- Vanderbilt Eye Institute, Vanderbilt University Medical Center, Nashville, Tennessee 37232-0654, USA
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Krüger J, Kunert-Keil C, Bisping F, Brinkmeier H. Transient receptor potential cation channels in normal and dystrophic mdx muscle. Neuromuscul Disord 2008; 18:501-13. [PMID: 18504127 DOI: 10.1016/j.nmd.2008.04.003] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2008] [Revised: 03/28/2008] [Accepted: 04/08/2008] [Indexed: 10/22/2022]
Abstract
To investigate the defective calcium regulation of dystrophin-deficient muscle fibres we studied gene expression and localization of non-voltage gated cation channels in normal and mdx mouse skeletal muscle. We found TRPC3, TRPC6, TRPV4, TRPM4 and TRPM7 to be the most abundant isoforms. Immunofluorescent staining of muscle cross-sections with antibodies against TRP proteins showed sarcolemmal localization of TRPC6 and TRPM7, both, for mdx and control. TRPV4 was found only in a fraction of fibres at the sarcolemma and around myonuclei, while TRPC3 staining revealed intracellular patches, preferentially in mdx muscle. Transcripts of low abundance coding for TRPC5, TRPA1 and TRPM1 channels were increased in mdx skeletal muscle at certain stages. The increased Ca(2+)-influx into dystrophin-deficient mdx fibres cannot be explained by increased gene expression of major TRP channels. However, a constant TRP channel expression in combination with the well described weaker Ca(2+)-handling system of mdx fibres may indicate an imbalance between Ca(2+)-influx and cellular Ca(2+)-control.
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Affiliation(s)
- Jana Krüger
- Institute of Pathophysiology, Ernst Moritz Arndt University of Greifswald, Greifswalder Street 11C, D-17495 Karlsburg, Germany
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