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Calzetta L, Page C, Matera MG, Cazzola M, Rogliani P. Use of human airway smooth muscle in vitro and ex vivo to investigate drugs for the treatment of chronic obstructive respiratory disorders. Br J Pharmacol 2024; 181:610-639. [PMID: 37859567 DOI: 10.1111/bph.16272] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 10/11/2023] [Accepted: 10/12/2023] [Indexed: 10/21/2023] Open
Abstract
Isolated airway smooth muscle has been extensively investigated since 1840 to understand the pharmacology of airway diseases. There has often been poor predictability from murine experiments to drugs evaluated in patients with asthma or chronic obstructive pulmonary disease (COPD). However, the use of isolated human airways represents a sensible strategy to optimise the development of innovative molecules for the treatment of respiratory diseases. This review aims to provide updated evidence on the current uses of isolated human airways in validated in vitro methods to investigate drugs in development for the treatment of chronic obstructive respiratory disorders. This review also provides historical notes on the pioneering pharmacological research on isolated human airway tissues, the key differences between human and animal airways, as well as the pivotal differences between human medium bronchi and small airways. Experiments carried out with isolated human bronchial tissues in vitro and ex vivo replicate many of the main anatomical, pathophysiological, mechanical and immunological characteristics of patients with asthma or COPD. In vitro models of asthma and COPD using isolated human airways can provide information that is directly translatable into humans with obstructive lung diseases. Regardless of the technique used to investigate drugs for the treatment of chronic obstructive respiratory disorders (i.e., isolated organ bath systems, videomicroscopy and wire myography), the most limiting factors to produce high-quality and repeatable data remain closely tied to the manual skills of the researcher conducting experiments and the availability of suitable tissue.
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Affiliation(s)
- Luigino Calzetta
- Department of Medicine and Surgery, Respiratory Disease and Lung Function Unit, University of Parma, Parma, Italy
| | - Clive Page
- Pulmonary Pharmacology Unit, Institute of Pharmaceutical Science, King's College London, London, UK
| | - Maria Gabriella Matera
- Unit of Pharmacology, Department of Experimental Medicine, University of Campania "Luigi Vanvitelli", Naples, Italy
| | - Mario Cazzola
- Unit of Respiratory Medicine, Department of Experimental Medicine, University of Rome "Tor Vergata", Rome, Italy
| | - Paola Rogliani
- Unit of Respiratory Medicine, Department of Experimental Medicine, University of Rome "Tor Vergata", Rome, Italy
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Sala S, Oakes PW. Stress fiber strain recognition by the LIM protein testin is cryptic and mediated by RhoA. Mol Biol Cell 2021; 32:1758-1771. [PMID: 34038160 PMCID: PMC8684727 DOI: 10.1091/mbc.e21-03-0156] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
The actin cytoskeleton is a key regulator of mechanical processes in cells. The family of LIM domain proteins have recently emerged as important mechanoresponsive cytoskeletal elements capable of sensing strain in the actin cytoskeleton. The mechanisms regulating this mechanosensitive behavior, however, remain poorly understood. Here we show that the LIM domain protein testin is peculiar in that despite the full-length protein primarily appearing diffuse in the cytoplasm, the C-terminal LIM domains alone recognize focal adhesions and strained actin, while the N-terminal domains alone recognize stress fibers. Phosphorylation mutations in the dimerization regions of testin, however, reveal its mechanosensitivity and cause it to relocate to focal adhesions and sites of strain in the actin cytoskeleton. Finally, we demonstrate that activated RhoA causes testin to adorn stress fibers and become mechanosensitive. Together, our data show that testin’s mechanoresponse is regulated in cells and provide new insights into LIM domain protein recognition of the actin cytoskeleton’s mechanical state.
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Affiliation(s)
- Stefano Sala
- Department of Cell and Molecular Physiology, Loyola University Chicago, Stritch School of Medicine, Maywood, IL 60153
| | - Patrick W Oakes
- Department of Cell and Molecular Physiology, Loyola University Chicago, Stritch School of Medicine, Maywood, IL 60153
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Castaneda PG, Cecchetelli AD, Pettit HN, Cram EJ. Gα/GSA-1 works upstream of PKA/KIN-1 to regulate calcium signaling and contractility in the Caenorhabditis elegans spermatheca. PLoS Genet 2020; 16:e1008644. [PMID: 32776941 PMCID: PMC7444582 DOI: 10.1371/journal.pgen.1008644] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2020] [Revised: 08/20/2020] [Accepted: 06/29/2020] [Indexed: 11/18/2022] Open
Abstract
Correct regulation of cell contractility is critical for the function of many biological systems. The reproductive system of the hermaphroditic nematode C. elegans contains a contractile tube of myoepithelial cells known as the spermatheca, which stores sperm and is the site of oocyte fertilization. Regulated contraction of the spermatheca pushes the embryo into the uterus. Cell contractility in the spermatheca is dependent on actin and myosin and is regulated, in part, by Ca2+ signaling through the phospholipase PLC-1, which mediates Ca2+ release from the endoplasmic reticulum. Here, we describe a novel role for GSA-1/Gαs, and protein kinase A, composed of the catalytic subunit KIN-1/PKA-C and the regulatory subunit KIN-2/PKA-R, in the regulation of Ca2+ release and contractility in the C. elegans spermatheca. Without GSA-1/Gαs or KIN-1/PKA-C, Ca2+ is not released, and oocytes become trapped in the spermatheca. Conversely, when PKA is activated through either a gain of function allele in GSA-1 (GSA-1(GF)) or by depletion of KIN-2/PKA-R, the transit times and total numbers, although not frequencies, of Ca2+ pulses are increased, and Ca2+ propagates across the spermatheca even in the absence of oocyte entry. In the spermathecal-uterine valve, loss of GSA-1/Gαs or KIN-1/PKA-C results in sustained, high levels of Ca2+ and a loss of coordination between the spermathecal bag and sp-ut valve. Additionally, we show that depleting phosphodiesterase PDE-6 levels alters contractility and Ca2+ dynamics in the spermatheca, and that the GPB-1 and GPB-2 Gβ subunits play a central role in regulating spermathecal contractility and Ca2+ signaling. This work identifies a signaling network in which Ca2+ and cAMP pathways work together to coordinate spermathecal contractions for successful ovulations.
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Affiliation(s)
- Perla G. Castaneda
- Department of Biology, Northeastern University, Boston, MA, United States
| | | | - Hannah N. Pettit
- Department of Biology, Northeastern University, Boston, MA, United States
| | - Erin J. Cram
- Department of Biology, Northeastern University, Boston, MA, United States
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Airway remodelling with spatial correlations: Implications for asthma pathogenesis. Respir Physiol Neurobiol 2020; 279:103469. [PMID: 32473215 DOI: 10.1016/j.resp.2020.103469] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 04/30/2020] [Accepted: 05/21/2020] [Indexed: 12/11/2022]
Abstract
Airway remodelling is a cardinal feature of asthma in which airways undergo structural changes - in particular, increased airway smooth muscle mass and total airway wall area. Remodelling has long been thought to have functional consequences in asthma due to geometric effects that can increase airway narrowing and luminal occlusion. Prior studies have examined the distribution of remodelling between and within patients, but none have yet considered the possibility for spatial correlations in airway remodelling. That is, is remodelling clustered locally, or interrelated along proximal and distal locations of the bronchial tree? In view of recent interest regarding airway remodelling produced by mechanical stimuli, we developed a mathematical model to examine whether spatial correlations in airway remodelling could arise due to cycles of bronchoconstriction and mechanotransduction. Further, we compared modelling predictions to the spatial distribution of airway remodelling in lungs from subjects with and without asthma. Results indicate that spatial correlations in airway remodelling do exist in vivo, and cycles of bronchoconstriction and mechanotransduction are one plausible mechanism for their origin. These findings offer insights into the evolution of airway remodelling in asthma, which may inform strategies for treatment and prevention.
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Sun X, Yang W, Gong S, Liang S, Gu S, Lu H, Liu J, Xu J. Diagnostic value of volumetric capnography in patients with chronic cough variant asthma. Clinics (Sao Paulo) 2020; 75:e1662. [PMID: 33084765 PMCID: PMC7536889 DOI: 10.6061/clinics/2020/e1662] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/09/2020] [Accepted: 05/12/2020] [Indexed: 11/18/2022] Open
Abstract
OBJECTIVES To evaluate the quantitative changes and diagnostic performance of volumetric capnography (VCap) parameters in patients with cough variant asthma. METHODS This cross-sectional study enrolled 31 patients with cough variant asthma and 30 patients with chronic cough without asthma between November 2010 and March 2012. VCap measurements were recorded at baseline, during the five steps of the histamine challenge, and after bronchodilation with salbutamol. They were then compared between the baseline and histamine challenge, and between the two groups. Receiver operating characteristic curve analysis was performed for different VCap measurements. RESULTS The slope of phase III (dc\dv3) and the ratio of phase III slope to phase II slope (SR23%) decreased from baseline upon challenge with 1.1 mg histamine in cough variant asthma patients but increased in patients with chronic cough without asthma. Additionally, the change upon challenge with 1.1 mg histamine in dc\dv3 from baseline (S6-S1dc\dv3) in cough variant asthma patients had the largest area under the curve (AUC) (0.814, 95% CI: 0.697-0.931; p<0.001). The AUC for change upon challenge with 1.1 mg histamine in SR23% from baseline was 0.755 (95%CI: 0.632-0.878; p<0.001). At a cutoff of 19.8, S6-S1 dc\dv3 had a sensitivity of 74.2% and specificity of 90.0% and at a cutoff of 40.7, S6-S1 SR23% had a sensitivity of 48.4% and specificity of 96.7%. CONCLUSION Patients with cough variant asthma exhibit distinct VCap responses for dead space parameters upon challenge with histamine in comparison to patients with chronic cough. VCap parameters like phase III slope and phase III/phase II slope ratio could be used to aid the diagnosis of cough variant asthma.
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Affiliation(s)
- Xiaoli Sun
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital Tongji University School of Medicine, Shanghai 200433, China
| | - Wenlan Yang
- Department of Pulmonary Function Test, Shanghai Pulmonary Hospital Tongji University School of Medicine, Shanghai 200433, China
| | - Sugang Gong
- Department of Cardio-Pulmonary Circulation, Shanghai Pulmonary Hospital Tongji University School of Medicine, Shanghai 200433, China
| | - Shuo Liang
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital Tongji University School of Medicine, Shanghai 200433, China
| | - Shuyi Gu
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital Tongji University School of Medicine, Shanghai 200433, China
| | - Haiwen Lu
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital Tongji University School of Medicine, Shanghai 200433, China
| | - Jinmin Liu
- Department of Cardio-Pulmonary Circulation, Shanghai Pulmonary Hospital Tongji University School of Medicine, Shanghai 200433, China
| | - Jinfu Xu
- Department of Respiratory and Critical Care Medicine, Shanghai Pulmonary Hospital Tongji University School of Medicine, Shanghai 200433, China
- *Corresponding author. E-mail:
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Sun X, Zhang Y, Yang W, Liu J. Comparison of capnovolumetry-derived dead space parameters with pulmonary function test in normal adults using histamine provocation. CLINICAL RESPIRATORY JOURNAL 2014; 9:238-46. [PMID: 24725373 DOI: 10.1111/crj.12133] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/10/2014] [Revised: 03/10/2014] [Accepted: 04/04/2014] [Indexed: 12/22/2022]
Abstract
OBJECTIVES This study in healthy adults was conducted to explore the clinical application of capnovolumetric indices as compared to lung function parameters using histamine provocation. METHODS Forty healthy subjects received aerosol histamine or salbutamol in an automatic stimulation system with escalating doses of histamine. Dead space volumes of capnovolumetry and lung function parameters were examined with increased concentrations of histamine at a fixed time interval. The doses of histamine were selected from 0.0562 mg-2.2 mg and 0.1 mg salbutamol was inhaled when a maximal dose of histamine was reached. Baseline values in each group were calculated prior to histamine inhalation. RESULTS Fowler dead space (VDF), Wolff dead space (VDW), threshold dead space (VDT), Bohr dead space (VDB), forced expiratory volume in 1 s (FEV1 ) and peak expiratory flow (PEF) showed a dose-dependent reduction following histamine provocation, but there were no statistical differences in the measurements at baseline and post S6 provocation. The value of dC3/DV at the maximal dose was significantly increased over its baseline value (P < 0.05). VDF, VDT and VDW were significantly increased after bronchodilator use (P < 0.05 or <0.01). The changes in capnovolumetry did not correspond with the results of lung function test. CONCLUSIONS The dC3/DV and airway dead spaces of capnovolumetry in healthy adults are significantly increased compared to lung function parameters before or after bronchodilator use, suggesting that capnovolumetry is feasible in diagnostic evaluation of airway reactivity, especially for persons who are unable to undertake lung function test.
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Affiliation(s)
- Xiaoli Sun
- Department of Respiratory Diseases, Shanghai Pulmonary Hospital, Tongji University, Shanghai, China
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Lee SL, Nekouzadeh A, Butler B, Pryse KM, McConnaughey WB, Nathan AC, Legant WR, Schaefer PM, Pless RB, Elson EL, Genin GM. Physically-induced cytoskeleton remodeling of cells in three-dimensional culture. PLoS One 2012; 7:e45512. [PMID: 23300512 PMCID: PMC3531413 DOI: 10.1371/journal.pone.0045512] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2012] [Accepted: 08/20/2012] [Indexed: 01/15/2023] Open
Abstract
Characterizing how cells in three-dimensional (3D) environments or natural tissues respond to biophysical stimuli is a longstanding challenge in biology and tissue engineering. We demonstrate a strategy to monitor morphological and mechanical responses of contractile fibroblasts in a 3D environment. Cells responded to stretch through specific, cell-wide mechanisms involving staged retraction and reinforcement. Retraction responses occurred for all orientations of stress fibers and cellular protrusions relative to the stretch direction, while reinforcement responses, including extension of cellular processes and stress fiber formation, occurred predominantly in the stretch direction. A previously unreported role of F-actin clumps was observed, with clumps possibly acting as F-actin reservoirs for retraction and reinforcement responses during stretch. Responses were consistent with a model of cellular sensitivity to local physical cues. These findings suggest mechanisms for global actin cytoskeleton remodeling in non-muscle cells and provide insight into cellular responses important in pathologies such as fibrosis and hypertension.
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Affiliation(s)
- Sheng-Lin Lee
- Department of Mechanical Engineering & Materials Science, Washington University, St. Louis, Missouri, United States of America
| | - Ali Nekouzadeh
- Department of Biomedical Engineering, Washington University, St. Louis, Missouri, United States of America
| | - Boyd Butler
- Department of Biological Sciences Texas Tech University, Lubbock, Texas, United States of America
| | - Kenneth M. Pryse
- Department of Biochemistry & Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - William B. McConnaughey
- Department of Biochemistry & Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Adam C. Nathan
- Department of Mechanical Engineering & Materials Science, Washington University, St. Louis, Missouri, United States of America
| | - Wesley R. Legant
- Department of Biomedical Engineering, Washington University, St. Louis, Missouri, United States of America
| | - Pascal M. Schaefer
- Department of Biology, Washington University, St. Louis, Missouri, United States of America
| | - Robert B. Pless
- Department of Computer Science and Engineering, Washington University, St. Louis, Missouri, United States of America
| | - Elliot L. Elson
- Department of Biochemistry & Molecular Biophysics, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Guy M. Genin
- Department of Mechanical Engineering & Materials Science, Washington University, St. Louis, Missouri, United States of America
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Stewart MP, Toyoda Y, Hyman AA, Müller DJ. Tracking mechanics and volume of globular cells with atomic force microscopy using a constant-height clamp. Nat Protoc 2012; 7:143-54. [DOI: 10.1038/nprot.2011.434] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
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MicroRNAs profiling in murine models of acute and chronic asthma: a relationship with mRNAs targets. PLoS One 2011. [PMID: 21305051 DOI: 10.1371/journal.pone.0016509.] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
BACKGROUND miRNAs are now recognized as key regulator elements in gene expression. Although they have been associated with a number of human diseases, their implication in acute and chronic asthma and their association with lung remodelling have never been thoroughly investigated. METHODOLOGY/PRINCIPAL FINDINGS In order to establish a miRNAs expression profile in lung tissue, mice were sensitized and challenged with ovalbumin mimicking acute, intermediate and chronic human asthma. Levels of lung miRNAs were profiled by microarray and in silico analyses were performed to identify potential mRNA targets and to point out signalling pathways and biological processes regulated by miRNA-dependent mechanisms. Fifty-eight, 66 and 75 miRNAs were found to be significantly modulated at short-, intermediate- and long-term challenge, respectively. Inverse correlation with the expression of potential mRNA targets identified mmu-miR-146b, -223, -29b, -29c, -483, -574-5p, -672 and -690 as the best candidates for an active implication in asthma pathogenesis. A functional validation assay was performed by cotransfecting in human lung fibroblasts (WI26) synthetic miRNAs and engineered expression constructs containing the coding sequence of luciferase upstream of the 3'UTR of various potential mRNA targets. The bioinformatics analysis identified miRNA-linked regulation of several signalling pathways, as matrix metalloproteinases, inflammatory response and TGF-β signalling, and biological processes, including apoptosis and inflammation. CONCLUSIONS/SIGNIFICANCE This study highlights that specific miRNAs are likely to be involved in asthma disease and could represent a valuable resource both for biological makers identification and for unveiling mechanisms underlying the pathogenesis of asthma.
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Garbacki N, Di Valentin E, Huynh-Thu VA, Geurts P, Irrthum A, Crahay C, Arnould T, Deroanne C, Piette J, Cataldo D, Colige A. MicroRNAs profiling in murine models of acute and chronic asthma: a relationship with mRNAs targets. PLoS One 2011; 6:e16509. [PMID: 21305051 PMCID: PMC3030602 DOI: 10.1371/journal.pone.0016509] [Citation(s) in RCA: 116] [Impact Index Per Article: 8.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2010] [Accepted: 01/03/2011] [Indexed: 12/16/2022] Open
Abstract
Background miRNAs are now recognized as key regulator elements in gene expression. Although they have been associated with a number of human diseases, their implication in acute and chronic asthma and their association with lung remodelling have never been thoroughly investigated. Methodology/Principal Findings In order to establish a miRNAs expression profile in lung tissue, mice were sensitized and challenged with ovalbumin mimicking acute, intermediate and chronic human asthma. Levels of lung miRNAs were profiled by microarray and in silico analyses were performed to identify potential mRNA targets and to point out signalling pathways and biological processes regulated by miRNA-dependent mechanisms. Fifty-eight, 66 and 75 miRNAs were found to be significantly modulated at short-, intermediate- and long-term challenge, respectively. Inverse correlation with the expression of potential mRNA targets identified mmu-miR-146b, -223, -29b, -29c, -483, -574-5p, -672 and -690 as the best candidates for an active implication in asthma pathogenesis. A functional validation assay was performed by cotransfecting in human lung fibroblasts (WI26) synthetic miRNAs and engineered expression constructs containing the coding sequence of luciferase upstream of the 3′UTR of various potential mRNA targets. The bioinformatics analysis identified miRNA-linked regulation of several signalling pathways, as matrix metalloproteinases, inflammatory response and TGF-β signalling, and biological processes, including apoptosis and inflammation. Conclusions/Significance This study highlights that specific miRNAs are likely to be involved in asthma disease and could represent a valuable resource both for biological makers identification and for unveiling mechanisms underlying the pathogenesis of asthma.
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Affiliation(s)
- Nancy Garbacki
- GIGA-Research, Laboratory of Connective Tissues Biology, University of Liège, Liège, Belgium
| | - Emmanuel Di Valentin
- GIGA-Research, Laboratory of Virology and Immunology, University of Liège, Liège, Belgium
| | - Vân Anh Huynh-Thu
- GIGA-Research, Systems and modeling, University of Liège, Liège, Belgium
| | - Pierre Geurts
- GIGA-Research, Systems and modeling, University of Liège, Liège, Belgium
| | - Alexandre Irrthum
- GIGA-Research, Systems and modeling, University of Liège, Liège, Belgium
| | - Céline Crahay
- GIGA-Research, Laboratory of Biology of Tumours and Development, University of Liège, Liège, Belgium
| | - Thierry Arnould
- Laboratory of Biochemistry and Cell Biology, University of Namur, Namur, Belgium
| | - Christophe Deroanne
- GIGA-Research, Laboratory of Connective Tissues Biology, University of Liège, Liège, Belgium
| | - Jacques Piette
- GIGA-Research, Laboratory of Virology and Immunology, University of Liège, Liège, Belgium
| | - Didier Cataldo
- GIGA-Research, Laboratory of Biology of Tumours and Development, University of Liège, Liège, Belgium
| | - Alain Colige
- GIGA-Research, Laboratory of Connective Tissues Biology, University of Liège, Liège, Belgium
- * E-mail:
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Wu M, Fannin J, Rice KM, Wang B, Blough ER. Effect of aging on cellular mechanotransduction. Ageing Res Rev 2011; 10:1-15. [PMID: 19932197 DOI: 10.1016/j.arr.2009.11.002] [Citation(s) in RCA: 61] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2009] [Revised: 11/11/2009] [Accepted: 11/16/2009] [Indexed: 12/27/2022]
Abstract
Aging is becoming a critical heath care issue and a burgeoning economic burden on society. Mechanotransduction is the ability of the cell to sense, process, and respond to mechanical stimuli and is an important regulator of physiologic function that has been found to play a role in regulating gene expression, protein synthesis, cell differentiation, tissue growth, and most recently, the pathophysiology of disease. Here we will review some of the recent findings of this field and attempt, where possible, to present changes in mechanotransduction that are associated with the aging process in several selected physiological systems, including musculoskeletal, cardiovascular, neuronal, respiratory systems and skin.
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Seow CY, Fredberg JJ. Emergence of airway smooth muscle functions related to structural malleability. J Appl Physiol (1985) 2010; 110:1130-5. [PMID: 21127211 DOI: 10.1152/japplphysiol.01192.2010] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
The function of a complex system such as a smooth muscle cell is the result of the active interaction among molecules and molecular aggregates. Emergent macroscopic manifestations of these molecular interactions, such as the length-force relationship and its associated length adaptation, are well documented, but the molecular constituents and organization that give rise to these emergent muscle behaviors remain largely unknown. In this minireview, we describe emergent properties of airway smooth muscle that seem to have originated from inherent fragility of the cellular structures, which has been increasingly recognized as a unique and important smooth muscle attribute. We also describe molecular interactions (based on direct and indirect evidence) that may confer malleability on fragile structural elements that in turn may allow the muscle to adapt to large and frequent changes in cell dimensions. Understanding how smooth muscle works may hinge on how well we can relate molecular events to its emergent macroscopic functions.
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Affiliation(s)
- Chun Y Seow
- Department of Pathology, James Hogg Research Centre, University of British Columbia, Vancouver, British Columbia, Canada.
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14
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Abstract
Living cells sense the rigidity of their environment and adapt their activity to it. In particular, cells cultured on elastic substrates align their shape and their traction forces along the direction of highest stiffness and preferably migrate towards stiffer regions. Although numerous studies investigated the role of adhesion complexes in rigidity sensing, less is known about the specific contribution of acto-myosin based contractility. Here we used a custom-made single-cell technique to measure the traction force as well as the speed of shortening of isolated myoblasts deflecting microplates of variable stiffness. The rate of force generation increased with increasing stiffness and followed a Hill force-velocity relationship. Hence, cell response to stiffness was similar to muscle adaptation to load, reflecting the force-dependent kinetics of myosin binding to actin. These results reveal an unexpected mechanism of rigidity sensing, whereby the contractile acto-myosin units themselves can act as sensors. This mechanism may translate anisotropy in substrate rigidity into anisotropy in cytoskeletal tension, and could thus coordinate local activity of adhesion complexes and guide cell migration along rigidity gradients.
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