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Innes-Gold SN, Berezney JP, Saleh OA. Single-Molecule Stretching Shows Glycosylation Sets Tension in the Hyaluronan-Aggrecan Bottlebrush. Biophys J 2020; 119:1351-1358. [PMID: 32918890 DOI: 10.1016/j.bpj.2020.08.016] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2020] [Revised: 08/13/2020] [Accepted: 08/17/2020] [Indexed: 11/18/2022] Open
Abstract
Large bottlebrush complexes formed from the polysaccharide hyaluronan (HA) and the proteoglycan aggrecan contribute to cartilage compression resistance and are necessary for healthy joint function. A variety of mechanical forces act on these complexes in the cartilage extracellular matrix, motivating the need for a quantitative description that links their structure and mechanical response. Studies using electron microscopy have imaged the HA-aggrecan brush but require adsorption to a surface, dramatically altering the complex from its native conformation. We use magnetic tweezers force spectroscopy to measure changes in extension and mechanical response of an HA chain as aggrecan monomers bind and form a bottlebrush. This technique directly measures changes undergone by a single complex with time and under varying solution conditions. Upon addition of aggrecan, we find a large swelling effect manifests when the HA chain is under very low external tension (i.e., stretching forces less than ∼1 pN). We use models of force-extension behavior to show that repulsion between the aggrecans induces an internal tension in the HA chain. Through reference to theories of bottlebrush polymer behavior, we demonstrate that the experimental values of internal tension are consistent with a polydisperse aggrecan population, likely caused by varying degrees of glycosylation. By enzymatically deglycosylating the aggrecan, we show that aggrecan glycosylation is the structural feature that causes HA stiffening. We then construct a simple stochastic binding model to show that variable glycosylation leads to a wide distribution of internal tensions in HA, causing variations in the mechanics at much longer length scales. Our results provide a mechanistic picture of how flexibility and size of HA and aggrecan lead to the brush architecture and mechanical properties of this important component of cartilage.
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Affiliation(s)
- Sarah N Innes-Gold
- Materials Department, University of California, Santa Barbara, Santa Barbara, California
| | - John P Berezney
- Materials Department, University of California, Santa Barbara, Santa Barbara, California
| | - Omar A Saleh
- Materials Department, University of California, Santa Barbara, Santa Barbara, California; Biomolecular Science and Engineering Program, University of California, Santa Barbara, Santa Barbara, California.
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Tonetti T, Vasques F, Rapetti F, Maiolo G, Collino F, Romitti F, Camporota L, Cressoni M, Cadringher P, Quintel M, Gattinoni L. Driving pressure and mechanical power: new targets for VILI prevention. ANNALS OF TRANSLATIONAL MEDICINE 2017; 5:286. [PMID: 28828361 DOI: 10.21037/atm.2017.07.08] [Citation(s) in RCA: 133] [Impact Index Per Article: 19.0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Several factors have been recognized as possible triggers of ventilator-induced lung injury (VILI). The first is pressure (thus the 'barotrauma'), then the volume (hence the 'volutrauma'), finally the cyclic opening-closing of the lung units ('atelectrauma'). Less attention has been paid to the respiratory rate and the flow, although both theoretical considerations and experimental evidence attribute them a significant role in the generation of VILI. The initial injury to the lung parenchyma is necessarily mechanical and it could manifest as an unphysiological distortion of the extracellular matrix and/or as micro-fractures in the hyaluronan, likely the most fragile polymer embedded in the matrix. The order of magnitude of the energy required to break a molecular bond between the hyaluronan and the associated protein is 1.12×10-16 Joules (J), 70-90% higher than the average energy delivered by a single breath of 1L assuming a lung elastance of 10 cmH2O/L (0.5 J). With a normal statistical distribution of the bond strength some polymers will be exposed each cycle to an energy large enough to rupture. Both the extracellular matrix distortion and the polymer fractures lead to inflammatory increase of capillary permeability with edema if a pulmonary blood flow is sufficient. The mediation analysis of higher vs. lower tidal volume and PEEP studies suggests that the driving pressure, more than tidal volume, is the best predictor of VILI, as inferred by increased mortality. This is not surprising, as both tidal volume and respiratory system elastance (resulting in driving pressure) may independently contribute to the mortality. For the same elastance driving pressure is a predictor similar to plateau pressure or tidal volume. Driving pressure is one of the components of the mechanical power, which also includes respiratory rate, flow and PEEP. Finding the threshold for mechanical power would greatly simplify assessment and prevention of VILI.
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Affiliation(s)
- Tommaso Tonetti
- Department of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Göttingen, Germany
| | - Francesco Vasques
- Department of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Göttingen, Germany
| | - Francesca Rapetti
- Department of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Göttingen, Germany
| | - Giorgia Maiolo
- Department of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Göttingen, Germany
| | - Francesca Collino
- Department of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Göttingen, Germany
| | - Federica Romitti
- Department of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Göttingen, Germany
| | - Luigi Camporota
- Department of Adult Critical Care, Guy's and St Thomas' NHS Foundation Trust, King's Health Partners, London, UK.,Division of Asthma, Allergy and Lung Biology, King's College London, London, UK
| | - Massimo Cressoni
- Department of Medicine and Surgery, University of Milano-Bicocca, Milan, Italy
| | - Paolo Cadringher
- Department of Pathophysiology and Transplants, University of Milan, Milan, Italy
| | - Michael Quintel
- Department of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Göttingen, Germany
| | - Luciano Gattinoni
- Department of Anesthesiology, Emergency and Intensive Care Medicine, University of Göttingen, Göttingen, Germany
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Yang Y, Jiang H. Shape and Dynamics of Adhesive Cells: Mechanical Response of Open Systems. PHYSICAL REVIEW LETTERS 2017; 118:208102. [PMID: 28581769 DOI: 10.1103/physrevlett.118.208102] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Indexed: 06/07/2023]
Abstract
Cell adhesion is an essential biological process. However, previous theoretical and experimental studies ignore a key variable, the changes of cellular volume and pressure, during the dynamic adhesion process. Here, we treat cells as open systems and propose a theoretical framework to investigate how the exchange of water and ions with the environment affects the shape and dynamics of cells adhered between two adhesive surfaces. We show that adherent cells can be either stable (convex or concave) or unstable (spontaneous rupture or collapse) depending on the adhesion energy density, the cell size, the separation of two adhesive surfaces, and the stiffness of the flexible surface. Strikingly, we find that the unstable states vanish when cellular volume and pressure are constant. We further show that the detachments of convex and concave cells are very different. The mechanical response of adherent cells is mainly determined by the competition between the loading rate and the regulation of the cellular volume and pressure. Finally, we show that as an open system the detachment of adherent cells is also significantly influenced by the loading history. Thus, our findings reveal a major difference between living cells and nonliving materials.
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Affiliation(s)
- Yuehua Yang
- CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Modern Mechanics, University of Science and Technology of China, Hefei, Anhui 230027, China
| | - Hongyuan Jiang
- CAS Key Laboratory of Mechanical Behavior and Design of Materials, Department of Modern Mechanics, University of Science and Technology of China, Hefei, Anhui 230027, China
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Lv M, Wang M, Cai W, Hao W, Yuan P, Kang Z. Characterisation of separated end hyaluronan oligosaccharides from leech hyaluronidase and evaluation of angiogenesis. Carbohydr Polym 2016; 142:309-16. [PMID: 26917404 DOI: 10.1016/j.carbpol.2016.01.052] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Revised: 01/22/2016] [Accepted: 01/26/2016] [Indexed: 12/14/2022]
Abstract
Hyaluronan oligosaccharides (o-HAs), especially saturated o-HAs, have attracted intensive attention due to their potential applications in medical treatments. In this study, the hydrolysis process of leech hyaluronidase (LHase) towards the hyaluronan was investigated by HPLC and HPLC/ESI-MS. The proportions of hyaluronan tetrasaccharide (HA4) with hexasaccharide (HA6), end products, were illustrated to have a relationship with the amount of LHase. Higher yield of HA4 was achieved with higher activity of LHase. After optimisation of the packing resin and operation parameters (balanced pH, elution concentration, elution volume and elution flow rate), the highly pure HA4 and HA6 were efficiently separated and prepared by combining ion exchange Q-Sepharose Fast Flow and size exclusion column chromatography. Compared with o-HAs (average Mr of 4000 Da), HA4 and HA6 were demonstrated to show higher activity for promoting angiogenesis, which was similar with the corresponding HA4 and HA6 produced by bovine testicular hyaluronidase. The pure HA4 and HA6 that prepared from LHase will attract intensive studies and be used in potential applications in near future.
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Affiliation(s)
- Mengxian Lv
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, Jiangsu, China
| | - Miao Wang
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, Jiangsu, China.
| | - Weiwei Cai
- Laboratory of Tumor Pharmacology, Wuxi Medical School, Jiangnan University, Wuxi 214122, China
| | - Wenxing Hao
- State Key Laboratory of Food Science and Technology, School of Food Science and Technology, Jiangnan University, 1800 Lihu Avenue, Wuxi 214122, Jiangsu, China
| | - Panhong Yuan
- The Key Laboratory of Industrial Biotechnology, School of Biotechnology, Jiangnan University, Wuxi 214122, China
| | - Zhen Kang
- The Key Laboratory of Industrial Biotechnology, School of Biotechnology, Jiangnan University, Wuxi 214122, China
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Yuan P, Lv M, Jin P, Wang M, Du G, Chen J, Kang Z. Enzymatic production of specifically distributed hyaluronan oligosaccharides. Carbohydr Polym 2015; 129:194-200. [DOI: 10.1016/j.carbpol.2015.04.068] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Revised: 04/24/2015] [Accepted: 04/25/2015] [Indexed: 12/21/2022]
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Han L, Grodzinsky AJ, Ortiz C. Nanomechanics of the Cartilage Extracellular Matrix. ANNUAL REVIEW OF MATERIALS RESEARCH 2011; 41:133-168. [PMID: 22792042 PMCID: PMC3392687 DOI: 10.1146/annurev-matsci-062910-100431] [Citation(s) in RCA: 129] [Impact Index Per Article: 9.9] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/22/2023]
Abstract
Cartilage is a hydrated biomacromolecular fiber composite located at the ends of long bones that enables proper joint lubrication, articulation, loading, and energy dissipation. Degradation of extracellular matrix molecular components and changes in their nanoscale structure greatly influence the macroscale behavior of the tissue and result in dysfunction with age, injury, and diseases such as osteoarthritis. Here, the application of the field of nanomechanics to cartilage is reviewed. Nanomechanics involves the measurement and prediction of nanoscale forces and displacements, intra- and intermolecular interactions, spatially varying mechanical properties, and other mechanical phenomena existing at small length scales. Experimental nanomechanics and theoretical nanomechanics have been applied to cartilage at varying levels of material complexity, e.g., nanoscale properties of intact tissue, the matrix associated with single cells, biomimetic molecular assemblies, and individual extracellular matrix biomolecules (such as aggrecan, collagen, and hyaluronan). These studies have contributed to establishing a fundamental mechanism-based understanding of native and engineered cartilage tissue function, quality, and pathology.
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Affiliation(s)
- Lin Han
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Alan J. Grodzinsky
- Department of Electrical Engineering and Computer Science, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
| | - Christine Ortiz
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139
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Abstract
Here it is reported that aggrecan, the highly negatively charged macromolecule in the cartilage extracellular matrix, undergoes Ca(2+)-mediated self-adhesion after static compression even in the presence of strong electrostatic repulsion in physiological-like solution conditions. Aggrecan was chemically end-attached onto gold-coated planar silicon substrates and gold-coated microspherical atomic force microscope probe tips (end radius R approximately 2.5 mum) at a density ( approximately 40 mg/mL) that simulates physiological conditions in the tissue ( approximately 20-80 mg/mL). Colloidal force spectroscopy was employed to measure the adhesion between opposing aggrecan monolayers in NaCl (0.001-1.0 M) and NaCl + CaCl(2) ([Cl(-)] = 0.15 M, [Ca(2+)] = 0 - 75 mM) aqueous electrolyte solutions. Aggrecan self-adhesion was found to increase with increasing surface equilibration time upon compression (0-30 s). Hydrogen bonding and physical entanglements between the chondroitin sulfate-glycosaminoglycan side chains are proposed as important factors contributing to aggrecan self-adhesion. Self-adhesion was found to significantly increase with decreasing bath ionic strength (and hence, electrostatic double-layer repulsion), as well as increasing Ca(2+) concentration due to the additional ion-bridging effects. It is hypothesized that aggrecan self-adhesion, and the macromolecular energy dissipation that results from this self-adhesion, could be important factors contributing to the self-assembled architecture and integrity of the cartilage extracellular matrix in vivo.
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