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Asaro RJ, Zhu Q. Vital erythrocyte phenomena: what can theory, modeling, and simulation offer? Biomech Model Mechanobiol 2020; 19:1361-1388. [DOI: 10.1007/s10237-020-01302-x] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2019] [Accepted: 01/22/2020] [Indexed: 12/14/2022]
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2
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Hoffman JF. Reflections on the crooked timber of red blood cell physiology. Blood Cells Mol Dis 2019; 79:102354. [PMID: 31449971 DOI: 10.1016/j.bcmd.2019.102354] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2019] [Accepted: 08/16/2019] [Indexed: 01/07/2023]
Affiliation(s)
- Joseph F Hoffman
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06520, United States.
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Myosin IIA interacts with the spectrin-actin membrane skeleton to control red blood cell membrane curvature and deformability. Proc Natl Acad Sci U S A 2018; 115:E4377-E4385. [PMID: 29610350 DOI: 10.1073/pnas.1718285115] [Citation(s) in RCA: 68] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The biconcave disk shape and deformability of mammalian RBCs rely on the membrane skeleton, a viscoelastic network of short, membrane-associated actin filaments (F-actin) cross-linked by long, flexible spectrin tetramers. Nonmuscle myosin II (NMII) motors exert force on diverse F-actin networks to control cell shapes, but a function for NMII contractility in the 2D spectrin-F-actin network of RBCs has not been tested. Here, we show that RBCs contain membrane skeleton-associated NMIIA puncta, identified as bipolar filaments by superresolution fluorescence microscopy. MgATP disrupts NMIIA association with the membrane skeleton, consistent with NMIIA motor domains binding to membrane skeleton F-actin and contributing to membrane mechanical properties. In addition, the phosphorylation of the RBC NMIIA heavy and light chains in vivo indicates active regulation of NMIIA motor activity and filament assembly, while reduced heavy chain phosphorylation of membrane skeleton-associated NMIIA indicates assembly of stable filaments at the membrane. Treatment of RBCs with blebbistatin, an inhibitor of NMII motor activity, decreases the number of NMIIA filaments associated with the membrane and enhances local, nanoscale membrane oscillations, suggesting decreased membrane tension. Blebbistatin-treated RBCs also exhibit elongated shapes, loss of membrane curvature, and enhanced deformability, indicating a role for NMIIA contractility in promoting membrane stiffness and maintaining RBC biconcave disk cell shape. As structures similar to the RBC membrane skeleton exist in many metazoan cell types, these data demonstrate a general function for NMII in controlling specialized membrane morphology and mechanical properties through contractile interactions with short F-actin in spectrin-F-actin networks.
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Biconcave shape of human red-blood-cell ghosts relies on density differences between the rim and dimple of the ghost's plasma membrane. Proc Natl Acad Sci U S A 2016; 113:14847-14851. [PMID: 27930321 DOI: 10.1073/pnas.1615452113] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
The shape of the human red blood cell is known to be a biconcave disk. It is evident from a variety of theoretical work that known physical properties of the membrane, such as its bending energy and elasticity, can explain the red-blood-cell biconcave shape as well as other shapes that red blood cells assume. But these analyses do not provide information on the underlying molecular causes. This paper describes experiments that attempt to identify some of the underlying determinates of cell shape. To this end, red-blood-cell ghosts were made by hypotonic hemolysis and then reconstituted such that they were smooth spheres in hypo-osmotic solutions and smooth biconcave discs in iso-osmotic solutions. The spherical ghosts were centrifuged onto a coated coverslip upon which they adhered. When the attached spheres were changed to biconcave discs by flushing with an iso-osmotic solution, the ghosts were observed to be mainly oriented in a flat alignment on the coverslip. This was interpreted to mean that, during centrifugation, the spherical ghosts were oriented by a dense band in its equatorial plane, parallel to the centrifugal field. This appears to be evidence that the difference in the densities between the rim and the dimple regions of red blood cells and their ghosts may be responsible for their biconcave shape.
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Malka R, Delgado FF, Manalis SR, Higgins JM. In vivo volume and hemoglobin dynamics of human red blood cells. PLoS Comput Biol 2014; 10:e1003839. [PMID: 25299941 PMCID: PMC4191880 DOI: 10.1371/journal.pcbi.1003839] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Accepted: 08/01/2014] [Indexed: 11/18/2022] Open
Abstract
Human red blood cells (RBCs) lose ∼30% of their volume and ∼20% of their hemoglobin (Hb) content during their ∼100-day lifespan in the bloodstream. These observations are well-documented, but the mechanisms for these volume and hemoglobin loss events are not clear. RBCs shed hemoglobin-containing vesicles during their life in the circulation, and this process is thought to dominate the changes in the RBC physical characteristics occurring during maturation. We combine theory with single-cell measurements to investigate the impact of vesiculation on the reduction in volume, Hb mass, and membrane. We show that vesicle shedding alone is sufficient to explain membrane losses but not volume or Hb losses. We use dry mass measurements of human RBCs to validate the models and to propose that additional unknown mechanisms control volume and Hb reduction and are responsible for ∼90% of the observed reduction. RBC population characteristics are used in the clinic to monitor and diagnose a wide range of conditions including malnutrition, inflammation, and cancer. Quantitative characterization of cellular maturation processes may help in the early detection of clinical conditions where maturation patterns are altered.
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Affiliation(s)
- Roy Malka
- Center for Systems Biology and Department of Pathology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail: (RM); (JMH)
| | - Francisco Feijó Delgado
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - Scott R. Manalis
- Koch Institute for Integrative Cancer Research, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
- Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, Massachusetts, United States of America
| | - John M. Higgins
- Center for Systems Biology and Department of Pathology, Massachusetts General Hospital, Boston, Massachusetts, United States of America
- Department of Systems Biology, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail: (RM); (JMH)
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Lázaro GR, Hernández-Machado A, Pagonabarraga I. Rheology of red blood cells under flow in highly confined microchannels: I. effect of elasticity. SOFT MATTER 2014; 10:7195-206. [PMID: 25105872 DOI: 10.1039/c4sm00894d] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
We analyze the rheology of dilute red blood cell suspensions in pressure driven flows at low Reynolds number, in terms of the morphologies and elasticity of the cells. We focus on narrow channels of width similar to the cell diameter, when the interactions with the walls dominate the cell dynamics. The suspension presents a shear-thinning behaviour, with a Newtonian-behaviour at low shear rates, an intermediate region of strong decay of the suspension viscosity, and an asymptotic regime at high shear rates in which the effective viscosity converges to that of the solvent. We identify the relevant aspects of cell elasticity that contribute to the rheological response of blood at high confinement. In a second paper, we will explore the focusing of red blood cells while flowing at high shear rates and how this effect is controlled by the geometry of the channel.
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Affiliation(s)
- Guillermo R Lázaro
- Departament d'Estructura i Constituents de la Materia, Universitat de Barcelona, Av. Diagonal 647, E08028 Barcelona, Spain.
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Gov N, Safran SA. Red blood cell shape and fluctuations: cytoskeleton confinement and ATP activity. J Biol Phys 2013; 31:453-64. [PMID: 23345910 DOI: 10.1007/s10867-005-6472-7] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022] Open
Abstract
We review recent theoretical work that analyzes experimental measurements of the shape and fluctuations of red blood cells. Particular emphasis is placed on the role of the cytoskeleton and cell elasticity and we contrast the situation of elastic cells with that of fluid-filled vesicles. In red blood cells (RBCs), the cytoskeleton consists of a two-dimensional network of spectrin proteins. Our analysis of the wave vector and frequency dependence of the fluctuation spectrum of RBCs indicates that the spectrin network acts as a confining potential that reduces the fluctuations of the lipid bilayer membrane. However, since the cytoskeleton is only sparsely connected to the bilayer, one cannot regard the composite cytoskeleton membrane as a polymerized object with a shear modulus. The sensitivity of RBC fluctuations and shapes to ATP concentration may reflect the transient defects induced in the cytoskeleton network by ATP.
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Affiliation(s)
- N Gov
- Department of Chemical Physics, Weizmann Institute of Science, Rehovot, Israel
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Sankaran VG, Ludwig LS, Sicinska E, Xu J, Bauer DE, Eng JC, Patterson HC, Metcalf RA, Natkunam Y, Orkin SH, Sicinski P, Lander ES, Lodish HF. Cyclin D3 coordinates the cell cycle during differentiation to regulate erythrocyte size and number. Genes Dev 2012; 26:2075-87. [PMID: 22929040 DOI: 10.1101/gad.197020.112] [Citation(s) in RCA: 92] [Impact Index Per Article: 7.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022]
Abstract
Genome-wide association studies (GWASs) have identified a genetic variant of moderate effect size at 6p21.1 associated with erythrocyte traits in humans. We show that this variant affects an erythroid-specific enhancer of CCND3. A Ccnd3 knockout mouse phenocopies these erythroid phenotypes, with a dramatic increase in erythrocyte size and a concomitant decrease in erythrocyte number. By examining human and mouse primary erythroid cells, we demonstrate that the CCND3 gene product cyclin D3 regulates the number of cell divisions that erythroid precursors undergo during terminal differentiation, thereby controlling erythrocyte size and number. We illustrate how cell type-specific specialization can occur for general cell cycle components-a finding resulting from the biological follow-up of unbiased human genetic studies.
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Peng Z, Asaro RJ, Zhu Q. Multiscale simulation of erythrocyte membranes. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2010; 81:031904. [PMID: 20365767 PMCID: PMC2876725 DOI: 10.1103/physreve.81.031904] [Citation(s) in RCA: 41] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/02/2009] [Revised: 01/15/2010] [Indexed: 05/07/2023]
Abstract
To quantitatively predict the mechanical response and mechanically induced remodeling of red blood cells, we developed a multiscale method to correlate distributions of internal stress with overall cell deformation. This method consists of three models at different length scales: in the complete cell level the membrane is modeled as two distinct layers of continuum shells using finite element method (Level III), in which the skeleton-bilayer interactions are depicted as a slide in the lateral (i.e., in-plane) direction (caused by the mobility of the skeleton-bilayer pinning points) and a normal contact force; the constitutive laws of the inner layer (the protein skeleton) are obtained from a molecular-based model (Level II); the mechanical properties of the spectrin (Sp, a key component of the skeleton), including its folding/unfolding reactions, are obtained with a stress-strain model (Level I). Model verification is achieved through comparisons with existing numerical and experimental studies in terms of the resting shape of the cell as well as cell deformations induced by micropipettes and optical tweezers. Detailed distributions of the interaction force between the lipid bilayer and the skeleton that may cause their dissociation and lead to phenomena such as vesiculation are predicted. Specifically, our model predicts correlation between the occurrence of Sp unfolding and increase in the mechanical load upon individual skeleton-bilayer pinning points. Finally a simulation of the necking process after skeleton-bilayer dissociation, a precursor of vesiculation, is conducted.
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Affiliation(s)
- Zhangli Peng
- Department of Structural Engineering, University of California, San Diego, La Jolla, CA 92093
| | - Robert J. Asaro
- Department of Structural Engineering, University of California, San Diego, La Jolla, CA 92093
| | - Qiang Zhu
- Department of Structural Engineering, University of California, San Diego, La Jolla, CA 92093
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Khairy K, Foo J, Howard J. Shapes of Red Blood Cells: Comparison of 3D Confocal Images with the Bilayer-Couple Model. Cell Mol Bioeng 2008; 1:173-181. [PMID: 21031149 DOI: 10.1007/s12195-008-0019-5] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Cells and organelles are shaped by the chemical and physical forces that bend cell membranes. The human red blood cell (RBC) is a model system for studying how such forces determine cell morphology. It is thought that RBCs, which are typically biconcave discoids, take the shape that minimizes their membrane-bending energies, subject to the constraints of fixed area and volume. However, recently it has been hypothesized that shear elasticity arising from the membrane-associated cytoskeleton (MS) is necessary to account for shapes of real RBCs, especially ones with highly curved features such as echinocytes. In this work we tested this hypothesis by following RBC shape changes using spherical harmonic series expansions of theoretical cell surfaces and those estimated from 3D confocal microscopy images of live cells. We found (i) quantitative agreement between shapes obtained from the theoretical model including the MS and real cells, (ii) that weakening the MS, by using urea (which denatures spectrin), leads to the theoretically predicted gradual decrease in spicule number of echinocytes, (iii) that the theory predicts that the MS is essential for stabilizing the discocyte morphology against changes in lipid composition, and that without it, the shape would default to the elliptocyte (a biconcave ellipsoid), (iv) that we were able to induce RBCs to adopt the predicted elliptocyte morphology by treating healthy discocytes with urea. The latter observation is consistent with the known connection between the blood disease hereditary elliptocytosis and spectrin mutations that weaken the cell cortex. We conclude that while the discocyte, in absence of shear, is indeed a minimum energy shape, its stabilization in healthy RBCs requires the MS, and that elliptocytosis can be explained based on purely mechanical considerations.
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Affiliation(s)
- Khaled Khairy
- Max Planck Institute of Molecular Cell Biology and Genetics, Pfotenhauerstrasse 108, D-01307 Dresden, Germany
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Abstract
This article mainly presents, in sequential panels of time, an overview of my professional involvements and laboratory experiences. I became smitten with red blood cells early on, and this passion remains with me to this day. I highlight certain studies, together with those who performed the work, recognizing that it was necessary to limit the details and the topics chosen for discussion. I am uncertain of the interest a personal account has for others, but at least it's here for the record.
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Affiliation(s)
- Joseph F Hoffman
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, USA.
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Hoffman JF. Further musings on some red blood cell problems for perspicacious physiologists. Blood Cells Mol Dis 2007; 39:56-62. [PMID: 17434767 DOI: 10.1016/j.bcmd.2007.03.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2007] [Accepted: 03/06/2007] [Indexed: 11/20/2022]
Affiliation(s)
- Joseph F Hoffman
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, 333 Cedar Street, New Haven, CT 06520-8026, USA.
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Hoffman JF, Inoué S. Directly observed reversible shape changes and hemoglobin stratification during centrifugation of human and Amphiuma red blood cells. Proc Natl Acad Sci U S A 2006; 103:2971-6. [PMID: 16477016 PMCID: PMC1413809 DOI: 10.1073/pnas.0510884103] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
This paper describes changes that occur in human and Amphiuma red blood cells observed during centrifugation with a special microscope. Dilute suspensions of cells were layered, in a centrifuge chamber, above an osmotically matched dense solution, containing Nycodenz, Ficoll, or Percoll (Pharmacia) that formed a density gradient that allowed the cells to slowly settle to an equilibrium position. Biconcave human red blood cells moved downward at low forces with minimum wobble. The cells oriented vertically when the force field was increased and Hb sedimented as the lower part of each cell became bulged and assumed a "bag-like" shape. The upper centripetal portion of the cell became thinner and remained biconcave. These changes occurred rapidly and were completely reversible upon lowering the centrifugal force. Bag-shaped cells, upon touching red cells in rouleau, immediately reverted to biconcave disks as they flipped onto a stack. Amphiuma red cells displayed a different type of reversible stratification and deformation at high force fields. Here the cells became stretched, with the nucleus now moving centrifugally, the Hb moving centripetally, and the bottom of the cells becoming thinner and clear. Nevertheless, the distribution of the marginal bands at the cells' rim was unchanged. We conclude that centrifugation, per se, while changing a red cell's shape and the distribution of its intracellular constituents, does so in a completely reversible manner. Centrifugation of red cells harboring altered or missing structural elements could provide information on shape determinants that are still unexplained.
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Affiliation(s)
- Joseph F Hoffman
- Department of Cellular and Molecular Physiology, Yale University, New Haven, CT 06520, USA.
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Miller JL. A genome-based approach for the study of erythroid biology and disease. Blood Cells Mol Dis 2005; 32:341-3. [PMID: 15121088 DOI: 10.1016/j.bcmd.2004.01.003] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2004] [Indexed: 10/26/2022]
Abstract
The human genome contains all elements of the erythroid transcriptome with the exception of those genes encoded in mitochondrial DNA. The concept of a "genome-based" approach for the study of erythroid biology and disease was envisioned in the mid-1990s as a logical offshoot of efforts to map the human genome. Although a completed human genome map was not expected until 2005 [Science 279 (1998) 23], the idea of creating a robust and retrievable description of erythroid gene activity was both encouraged and supported on the NIDDK Bethesda campus of the National Institutes of Health. The 5-10-year goals were organized into three parts. The initial project goal involved the collection of sequence data derived from mRNA expressed in developmentally staged erythroblasts. Those cells were isolated prospectively by flow cytometry monitoring of CD71 and glycophorin A expression patterns. Next, the sequence data was organized into a database and integrated with related information available in the public domain. The paramount goal of the project continues to be clinical application. As discussed in this paper, progress already made in each of these areas suggests that genome-based approaches will greatly facilitate future studies of erythroid biology and disease.
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Affiliation(s)
- Jeffery L Miller
- Laboratory of Chemical Biology, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Room 9B127, 9000 Rockville Pike, MSC 1822, Bethesda, MD 20892-1822, USA.
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Affiliation(s)
- Joseph F Hoffman
- Department of Cellular and Molecular Physiology, Yale University School of Medicine, New Haven, CT 06520-8026, USA.
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Gov NS, Safran SA. Red blood cell membrane fluctuations and shape controlled by ATP-induced cytoskeletal defects. Biophys J 2004; 88:1859-74. [PMID: 15613626 PMCID: PMC1305240 DOI: 10.1529/biophysj.104.045328] [Citation(s) in RCA: 193] [Impact Index Per Article: 9.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
We show theoretically how adenosine 5'-triphosphate (ATP)-induced dynamic dissociations of spectrin filaments (from each other and from the membrane) in the cytoskeleton network of red blood cells (RBC) can explain in a unified manner both the measured fluctuation amplitude as well as the observed shape transformations as a function of intracellular ATP concentration. Static defects can be induced by external stresses such as those present when RBCs pass through small capillaries. We suggest that the partially freed actin at these defect sites may explain the activation of the CFTR membrane-bound protein and the subsequent release of ATP by RBCs subjected to deformations. Our theoretical predictions can be tested by experiments that measure the correlation between variations in the binding of actin to spectrin, the activity of CFTR, and the amount of ATP released.
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Affiliation(s)
- N S Gov
- Department of Materials and Interfaces, The Weizmann Institute of Science, Rehovot 76100, Israel.
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Abstract
Two ideas explain the mechanism of shape regulation: the lipid bilayer coupled theory and the protein network scaffold theory. Recently, several important articles have been published on the former theory. However, many phenomena argue against the theory, including behavior of ghosts and triton shells, various types of manipulation of proteins, and fixation of the shape by the addition of large reagents outside the cell. Moreover, hereditary spherocytosis shows normal, uneven distribution of phospholipids, and hereditary and artificial defects of a membrane protein show spherocytes or elliptocytes. The liquid state of the lipid layer does not seem to support the shape or mechanical characteristics. On the other hand, all of these phenomena argue for the protein network scaffold theory. Characteristics of each protein and interactions among proteins are now being clarified, but this theory and the author's own ideas still lack decisive evidence.
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Affiliation(s)
- Makoto Nakao
- Professor Emeritus, Tokyo Medical and Dental University, School of Medicine, Tokyo, Japan.
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