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Piskova T, Kozyrina AN, Di Russo J. Mechanobiological implications of age-related remodelling in the outer retina. BIOMATERIALS ADVANCES 2023; 147:213343. [PMID: 36801797 DOI: 10.1016/j.bioadv.2023.213343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/06/2022] [Revised: 02/01/2023] [Accepted: 02/10/2023] [Indexed: 02/17/2023]
Abstract
The outer retina consists of the light-sensitive photoreceptors, the pigmented epithelium, and the choroid, which interact in a complex manner to sustain homeostasis. The organisation and function of these cellular layers are mediated by the extracellular matrix compartment named Bruch's membrane, situated between the retinal epithelium and the choroid. Like many tissues, the retina experiences age-related structural and metabolic changes, which are relevant for understanding major blinding diseases of the elderly, such as age-related macular degeneration. Compared with other tissues, the retina mainly comprises postmitotic cells, making it less able to maintain its mechanical homeostasis over the years functionally. Aspects of retinal ageing, like the structural and morphometric changes of the pigment epithelium and the heterogenous remodelling of the Bruch's membrane, imply changes in tissue mechanics and may affect functional integrity. In recent years, findings in the field of mechanobiology and bioengineering highlighted the importance of mechanical changes in tissues for understanding physiological and pathological processes. Here, we review the current knowledge of age-related changes in the outer retina from a mechanobiological perspective, aiming to generate food for thought for future mechanobiology studies in the outer retina.
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Affiliation(s)
- Teodora Piskova
- Interdisciplinary Centre for Clinical Research, RWTH Aachen University, Pauwelstrasse 30, 52074 Aachen, Germany; Institute of Molecular and Cellular Anatomy, RWTH Aachen University, Wendlingweg 2, 52074 Aachen, Germany
| | - Aleksandra N Kozyrina
- Interdisciplinary Centre for Clinical Research, RWTH Aachen University, Pauwelstrasse 30, 52074 Aachen, Germany; Institute of Molecular and Cellular Anatomy, RWTH Aachen University, Wendlingweg 2, 52074 Aachen, Germany
| | - Jacopo Di Russo
- Interdisciplinary Centre for Clinical Research, RWTH Aachen University, Pauwelstrasse 30, 52074 Aachen, Germany; Institute of Molecular and Cellular Anatomy, RWTH Aachen University, Wendlingweg 2, 52074 Aachen, Germany; DWI - Leibniz-Institute for Interactive Materials, Forckenbeckstrasse 50, 52074 Aachen, Germany.
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Cao X, Zhang B, Zhao N. Contrastive factors of activity and crowding on conformational properties of a flexible polymer. Chem Phys Lett 2020. [DOI: 10.1016/j.cplett.2020.137213] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
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Ge J, Gargey A, Nesmelova IV, Nesmelov YE. CaATP prolongs strong actomyosin binding and promotes futile myosin stroke. J Muscle Res Cell Motil 2019; 40:389-398. [PMID: 31556008 DOI: 10.1007/s10974-019-09556-4] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/26/2019] [Accepted: 09/18/2019] [Indexed: 12/15/2022]
Abstract
Calcium plays an essential role in muscle contraction, regulating actomyosin interaction by binding troponin of thin filaments. There are several buffers for calcium in muscle, and those buffers play a crucial role in the formation of the transient calcium wave in sarcomere upon muscle activation. One such calcium buffer in muscle is ATP. ATP is a fuel molecule, and the important role of MgATP in muscle is to bind myosin and supply energy for the power stroke. Myosin is not a specific ATPase, and CaATP also supports myosin ATPase activity. The concentration of CaATP in sarcomeres reaches 1% of all ATP available. Since 294 myosin molecules form a thick filament, naïve estimation gives three heads per filament with CaATP bound, instead of MgATP. We found that CaATP dissociates actomyosin slower than MgATP, thus increasing the time of the strong actomyosin binding. The rate of the basal CaATPase is faster than that of MgATPase, myosin readily produces futile stroke with CaATP. When calcium is upregulated, as in malignant hyperthermia, kinetics of myosin and actomyosin interaction with CaATP suggest that myosin CaATPase activity may contribute to observed muscle rigidity and enhanced muscle thermogenesis.
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Affiliation(s)
- Jinghua Ge
- Department of Physics and Optical Science, University of North Carolina Charlotte, 9201 University City Blvd, Charlotte, NC, 28223, USA
- Center for Biomedical Engineering and Science, University of North Carolina, Charlotte, NC, 28223, USA
| | - Akhil Gargey
- Department of Physics and Optical Science, University of North Carolina Charlotte, 9201 University City Blvd, Charlotte, NC, 28223, USA
- Center for Biomedical Engineering and Science, University of North Carolina, Charlotte, NC, 28223, USA
- Department of Biological Science, University of North Carolina Charlotte, Charlotte, NC, 28223, USA
| | - Irina V Nesmelova
- Department of Physics and Optical Science, University of North Carolina Charlotte, 9201 University City Blvd, Charlotte, NC, 28223, USA
- Center for Biomedical Engineering and Science, University of North Carolina, Charlotte, NC, 28223, USA
| | - Yuri E Nesmelov
- Department of Physics and Optical Science, University of North Carolina Charlotte, 9201 University City Blvd, Charlotte, NC, 28223, USA.
- Center for Biomedical Engineering and Science, University of North Carolina, Charlotte, NC, 28223, USA.
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Huff HC, Maroutsos D, Das A. Lipid composition and macromolecular crowding effects on CYP2J2-mediated drug metabolism in nanodiscs. Protein Sci 2019; 28:928-940. [PMID: 30861250 DOI: 10.1002/pro.3603] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2019] [Accepted: 03/11/2019] [Indexed: 01/13/2023]
Abstract
Lipid composition and macromolecular crowding are key external effectors of protein activity and stability whose role varies between different proteins. Therefore, it is imperative to study their effects on individual protein function. CYP2J2 is a membrane-bound cytochrome P450 in the heart involved in the metabolism of fatty acids and xenobiotics. In order to facilitate this metabolism, cytochrome P450 reductase (CPR), transfers electrons to CYP2J2 from NADPH. Herein, we use nanodiscs to show that lipid composition of the membrane bilayer affects substrate metabolism of the CYP2J2-CPR nanodisc (ND) system. Differential effects on both NADPH oxidation and substrate metabolism by CYP2J2-CPR are dependent on the lipid composition. For instance, sphingomyelin containing nanodiscs produced more secondary substrate metabolites than discs of other lipid compositions, implying a possible conformational change leading to processive metabolism. Furthermore, we demonstrate that macromolecular crowding plays a role in the lipid-solubilized CYP2J2-CPR system by increasing the Km and decreasing the Vmax , and effect that is size-dependent. Crowding also affects the CYP2J2-CPR-ND system by decreasing both the Km and Vmax for Dextran-based macromolecular crowding agents, implying an increase in substrate affinity but a lack of metabolism. Finally, protein denaturation studies show that crowding agents destabilize CYP2J2, while the multidomain protein CPR is stabilized. Overall, these studies are the first report on the role of the surrounding lipid environment and macromolecular crowding in modulating enzymatic function of CYP2J2-CPR membrane protein system.
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Affiliation(s)
- Hannah C Huff
- Department of Chemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
| | - Demetri Maroutsos
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
| | - Aditi Das
- Department of Biochemistry, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801.,Beckman Institute for Advanced Science and Technology, Division of Nutritional Science, Neuroscience Program, and Department of Bioengineering, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801.,Department of Comparative Biosciences, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801
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Gargey A, Ge J, Tkachev YV, Nesmelov YE. Electrostatic interactions in the force-generating region of the human cardiac myosin modulate ADP dissociation from actomyosin. Biochem Biophys Res Commun 2019; 509:978-982. [PMID: 30654937 DOI: 10.1016/j.bbrc.2019.01.045] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2018] [Accepted: 01/08/2019] [Indexed: 10/27/2022]
Abstract
Human cardiac myosin has two isoforms, alpha and beta, sharing significant sequence similarity, but different in kinetics: ADP release from actomyosin is an order of magnitude faster in the alpha myosin isoform. Apparently, small differences in the sequence are responsible for distinct local inter-residue interactions within alpha and beta isoforms, leading to such a dramatic difference in the rate of ADP release. Our analysis of structural kinetics of alpha and beta isoforms using molecular dynamics simulations revealed distinct dynamics of SH1:SH2 helix within the force-generation region of myosin head. The simulations showed that the residue R694 of the helix forms two permanent salt bridges in the beta isoform, which are not present in the alpha isoform. We hypothesized that the isoform-specific electrostatic interactions play a role in the difference of kinetic properties of myosin isoforms. We prepared R694N mutant in the beta isoform background to destabilize electrostatic interactions in the force-generating region of the myosin head. Our experimental data confirm faster ADP release from R694N actomyosin mutant, but is not as dramatic as the difference of kinetics of ADP release in the alpha and beta isoforms.
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Affiliation(s)
- Akhil Gargey
- Department of Physics and Optical Science, University of North Carolina Charlotte, Charlotte, NC, 28223, USA; Department of Biological Science, University of North Carolina Charlotte, Charlotte, NC, 28223, USA
| | - Jinghua Ge
- Department of Physics and Optical Science, University of North Carolina Charlotte, Charlotte, NC, 28223, USA
| | - Yaroslav V Tkachev
- Department of Physics and Optical Science, University of North Carolina Charlotte, Charlotte, NC, 28223, USA
| | - Yuri E Nesmelov
- Department of Physics and Optical Science, University of North Carolina Charlotte, Charlotte, NC, 28223, USA; Center for Biomedical Engineering and Science, University of North Carolina, Charlotte, NC, 28223, USA.
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Do Actomyosin Single-Molecule Mechanics Data Predict Mechanics of Contracting Muscle? Int J Mol Sci 2018; 19:ijms19071863. [PMID: 29941816 PMCID: PMC6073448 DOI: 10.3390/ijms19071863] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2018] [Revised: 06/19/2018] [Accepted: 06/20/2018] [Indexed: 12/15/2022] Open
Abstract
In muscle, but not in single-molecule mechanics studies, actin, myosin and accessory proteins are incorporated into a highly ordered myofilament lattice. In view of this difference we compare results from single-molecule studies and muscle mechanics and analyze to what degree data from the two types of studies agree with each other. There is reasonable correspondence in estimates of the cross-bridge power-stroke distance (7–13 nm), cross-bridge stiffness (~2 pN/nm) and average isometric force per cross-bridge (6–9 pN). Furthermore, models defined on the basis of single-molecule mechanics and solution biochemistry give good fits to experimental data from muscle. This suggests that the ordered myofilament lattice, accessory proteins and emergent effects of the sarcomere organization have only minor modulatory roles. However, such factors may be of greater importance under e.g., disease conditions. We also identify areas where single-molecule and muscle data are conflicting: (1) whether force generation is an Eyring or Kramers process with just one major power-stroke or several sub-strokes; (2) whether the myofilaments and the cross-bridges have Hookean or non-linear elasticity; (3) if individual myosin heads slip between actin sites under certain conditions, e.g., in lengthening; or (4) if the two heads of myosin cooperate.
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Shutova MS, Svitkina TM. Mammalian nonmuscle myosin II comes in three flavors. Biochem Biophys Res Commun 2018; 506:394-402. [PMID: 29550471 DOI: 10.1016/j.bbrc.2018.03.103] [Citation(s) in RCA: 42] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2018] [Accepted: 03/13/2018] [Indexed: 12/16/2022]
Abstract
Nonmuscle myosin II is an actin-based motor that executes numerous mechanical tasks in cells including spatiotemporal organization of the actin cytoskeleton, adhesion, migration, cytokinesis, tissue remodeling, and membrane trafficking. Nonmuscle myosin II is ubiquitously expressed in mammalian cells as a tissue-specific combination of three paralogs. Recent studies reveal novel specific aspects of their kinetics, intracellular regulation and functions. On the other hand, the three paralogs also can copolymerize and cooperate in cells. Here we review the recent advances from the prospective of how distinct features of the three myosin II paralogs adapt them to perform specialized and joint tasks in the cell.
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Affiliation(s)
- Maria S Shutova
- Department of Biology, University of Pennsylvania, Philadelphia, PA, 19104, USA
| | - Tatyana M Svitkina
- Department of Biology, University of Pennsylvania, Philadelphia, PA, 19104, USA.
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Marianelli AM, Miller BM, Keating CD. Impact of macromolecular crowding on RNA/spermine complex coacervation and oligonucleotide compartmentalization. SOFT MATTER 2018; 14:368-378. [PMID: 29265152 DOI: 10.1039/c7sm02146a] [Citation(s) in RCA: 43] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
We report the effect of neutral macromolecular crowders poly(ethylene glycol) (PEG) (8 kDa) and Ficoll (70 kDa) on liquid-liquid phase separation in a polyuridylic acid (polyU)/spermine complex coacervate system. The addition of PEG decreased both the amount of spermine required for phase separation and the coacervation temperature (TC). We interpret these effects on phase behavior as arising due to excluded volume and preferential interactions on both the secondary structure/condensation of spermine-associated polyU molecules and on the association of soluble polyU/spermine polyelectrolyte complexes to form coacervate droplets. Examination of coacervates formed in the presence of fluorescently-labeled PEG or Ficoll crowders indicated that Ficoll is accumulated while PEG is excluded from the coacervate phase, which provides further insight into the differences in phase behavior. Crowding agents impact distribution of a biomolecular solute: partitioning of a fluorescently-labeled U15 RNA oligomer into the polyU/spermine coacervates was increased approximately two-fold by 20 wt% Ficoll 70 kDa and by more than two orders of magnitude by 20 wt% PEG 8 kDa. The volume of the coacervate phase decreased in the presence of crowder relative to a dilute buffer solution. These findings indicate that potential impacts of macromolecular crowding on phase behavior and solute partitioning should be considered in model systems for intracellular membraneless organelles.
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Affiliation(s)
- A M Marianelli
- Department of Chemistry, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
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Benny P, Raghunath M. Making microenvironments: A look into incorporating macromolecular crowding into in vitro experiments, to generate biomimetic microenvironments which are capable of directing cell function for tissue engineering applications. J Tissue Eng 2017; 8:2041731417730467. [PMID: 29051808 PMCID: PMC5638150 DOI: 10.1177/2041731417730467] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2017] [Accepted: 08/09/2017] [Indexed: 01/07/2023] Open
Abstract
Biomimetic microenvironments are key components to successful cell culture and tissue engineering in vitro. One of the most accurate biomimetic microenvironments is that made by the cells themselves. Cell-made microenvironments are most similar to the in vivo state as they are cell-specific and produced by the actual cells which reside in that specific microenvironment. However, cell-made microenvironments have been challenging to re-create in vitro due to the lack of extracellular matrix composition, volume and complexity which are required. By applying macromolecular crowding to current cell culture protocols, cell-made microenvironments, or cell-derived matrices, can be generated at significant rates in vitro. In this review, we will examine the causes and effects of macromolecular crowding and how it has been applied in several in vitro systems including tissue engineering.
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Affiliation(s)
- Paula Benny
- Department of Biochemistry, National University of Singapore, Singapore
| | - Michael Raghunath
- Department of Biochemistry, National University of Singapore, Singapore.,Institute of Chemistry and Biotechnology, Zurich University of Applied Sciences, Wädenswil, Switzerland
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