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Mylvaganam S, Riedl M, Vega A, Collins RF, Jaqaman K, Grinstein S, Freeman SA. Stabilization of Endothelial Receptor Arrays by a Polarized Spectrin Cytoskeleton Facilitates Rolling and Adhesion of Leukocytes. Cell Rep 2021; 31:107798. [PMID: 32579925 PMCID: PMC7548125 DOI: 10.1016/j.celrep.2020.107798] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2020] [Revised: 04/15/2020] [Accepted: 06/01/2020] [Indexed: 12/15/2022] Open
Abstract
Multivalent complexes of endothelial adhesion receptors (e.g., selectins) engage leukocytes to orchestrate their migration to inflamed tissues. Proper anchorage and sufficient density (clustering) of endothelial receptors are required for efficient leukocyte capture and rolling. We demonstrate that a polarized spectrin network dictates the stability of the endothelial cytoskeleton, which is attached to the apical membrane, at least in part, by the abundant transmembrane protein CD44. Single-particle tracking revealed that CD44 undergoes prolonged periods of immobilization as it tethers to the cytoskeleton. The CD44-spectrin "picket fence" alters the behavior of bystander molecules-notably, selectins-curtailing their mobility, inducing their apical accumulation, and favoring their clustering within caveolae. Accordingly, depletion of either spectrin or CD44 virtually eliminated leukocyte rolling and adhesion to the endothelium. Our results indicate that a unique spectrin-based apical cytoskeleton tethered to transmembrane pickets-notably, CD44-is essential for proper extravasation of leukocytes in response to inflammation.
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Affiliation(s)
- Sivakami Mylvaganam
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, 686 Bay Street, 19-9800, Toronto, ON M5G 0A4, Canada; Department of Biochemistry, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada
| | - Magdalena Riedl
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, 686 Bay Street, 19-9800, Toronto, ON M5G 0A4, Canada
| | - Anthony Vega
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Lyda Hill Department of Bioinformatics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Richard F Collins
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, 686 Bay Street, 19-9800, Toronto, ON M5G 0A4, Canada
| | - Khuloud Jaqaman
- Department of Biophysics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA; Lyda Hill Department of Bioinformatics, University of Texas Southwestern Medical Center, Dallas, TX 75390, USA
| | - Sergio Grinstein
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, 686 Bay Street, 19-9800, Toronto, ON M5G 0A4, Canada; Department of Biochemistry, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada; Keenan Research Centre for Biomedical Science, St. Michael's Hospital, Toronto, ON M5B 1W8, Canada.
| | - Spencer A Freeman
- Program in Cell Biology, Peter Gilgan Centre for Research and Learning, Hospital for Sick Children, 686 Bay Street, 19-9800, Toronto, ON M5G 0A4, Canada; Department of Biochemistry, University of Toronto, 1 King's College Circle, Toronto, ON M5S 1A8, Canada.
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Abstract
Catch bond, whose lifetime increases with applied tensile force, can often mediate rolling adhesion of cells in a hydrodynamic environment. However, the mechanical mechanism governing the kinetics of rolling adhesion of cells through catch-bond under shear flow is not yet clear. In this study, a mechanical model is proposed for catch-bond-mediated cell adhesion in shear flow. The stochastic reaction of bond formation and dissociation is described as a Markovian process, whereas the dynamic motion of cells follows classical analytical mechanics. The steady state of cells significantly depends on the shear rate of flow. The upper and lower critical shear rates required for cell detachment and attachment are extracted, respectively. When the shear rate increases from the lower threshold to the upper threshold, cell rolling became slower and more regular, implying the flow-enhanced adhesion phenomenon. Our results suggest that this flow-enhanced stability of rolling adhesion is attributed to the competition between stochastic reactions of bonds and dynamics of cell rolling, instead of force lengthening the lifetime of catch bonds, thereby challenging the current view in understanding the mechanism behind this flow-enhanced adhesion phenomenon. Moreover, the loading history of flow defining bistability of cell adhesion in shear flow is predicted. These theoretical predictions are verified by Monte Carlo simulations and are related to the experimental observations reported in literature.
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Affiliation(s)
- Long Li
- Key Laboratory of Mechanics on Disaster and Environment in Western China, Ministry of Education, College of Civil Engineering and Mechanics, Lanzhou University, Lanzhou 730000, China;
- PULS Group, Institute for Theoretical Physics, FAU Erlangen-Nürnberg, 91058 Erlangen, Germany
- Correspondence: (L.L.); (J.W.)
| | - Wei Kang
- Key Laboratory of Mechanics on Disaster and Environment in Western China, Ministry of Education, College of Civil Engineering and Mechanics, Lanzhou University, Lanzhou 730000, China;
| | - Jizeng Wang
- Key Laboratory of Mechanics on Disaster and Environment in Western China, Ministry of Education, College of Civil Engineering and Mechanics, Lanzhou University, Lanzhou 730000, China;
- Correspondence: (L.L.); (J.W.)
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Abstract
This mini review highlights several interesting aspects of glycan-mediated interactions that are common between cells, bacteria, and viruses. Glycans are ubiquitously found on all living cells, and in the extracellular milieu of multicellular organisms. They are known to mediate initial binding and recognition events of both immune cells and pathogens with their target cells or tissues. The host target tissues are hidden under a layer of secreted glycosylated decoy targets. In addition, pathogens can utilize and display host glycans to prevent identification as foreign by the host’s immune system (molecular mimicry). Both the host and pathogens continually evolve. The host evolves to prevent infection and the pathogens evolve to evade host defenses. Many pathogens express both glycan-binding proteins and glycosidases. Interestingly, these proteins are often located at the tip of elongated protrusions in bacteria, or in the leading edge of the cell. Glycan-protein interactions have low affinity and, as a result, multivalent interactions are often required to achieve biologically relevant binding. These enable dynamic forms of adhesion mechanisms, reviewed here, and include rolling (cells), stick and roll (bacteria) or surfacing (viruses).
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Affiliation(s)
- Miriam Cohen
- Depatment of Cellular and Molecular Medicine, University of California, San Diego, 9500 Gilman Drive, BRF2 MC 0687, La Jolla, CA 92093-0687, USA.
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Pepper LR, Parthasarathy R, Robbins GP, Dang NN, Hammer DA, Boder ET. Isolation of αL I domain mutants mediating firm cell adhesion using a novel flow-based sorting method. Protein Eng Des Sel 2013; 26:515-21. [PMID: 23788664 PMCID: PMC3711393 DOI: 10.1093/protein/gzt028] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/11/2013] [Revised: 05/07/2013] [Accepted: 05/09/2013] [Indexed: 11/12/2022] Open
Abstract
The inserted (I) domain of αLβ2 integrin (LFA-1) contains the entire binding site of the molecule. It mediates both rolling and firm adhesion of leukocytes at sites of inflammation depending on the activation state of the integrin. The affinity change of the entire integrin can be mimicked by the I domain alone through mutations that affect the conformation of the molecule. High-affinity mutants of the I domain have been discovered previously using both rational design and directed evolution. We have found that binding affinity fails to dictate the behavior of I domain adhesion under shear flow. In order to better understand I domain adhesion, we have developed a novel panning method to separate yeast expressing a library of I domain variants on the surface by adhesion under flow. Using conditions analogous to those experienced by cells interacting with the post-capillary vascular endothelium, we have identified mutations supporting firm adhesion that are not found using typical directed evolution techniques that select for tight binding to soluble ligands. Mutants isolated using this method do not cluster with those found by sorting with soluble ligand. Furthermore, these mutants mediate shear-driven cell rolling dynamics decorrelated from binding affinity, as previously observed for I domains bearing engineered disulfide bridges to stabilize activated conformational states. Characterization of these mutants supports a greater understanding of the structure-function relationship of the αL I domain, and of the relationship between applied force and bioadhesion in a broader context.
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Affiliation(s)
- Lauren R. Pepper
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | | | - Gregory P. Robbins
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Nicholas N. Dang
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Daniel A. Hammer
- Department of Bioengineering, University of Pennsylvania, Philadelphia, PA 19104, USA
- Department of Chemical and Biomolecular Engineering, University of Pennsylvania, Philadelphia, PA 19104, USA
| | - Eric T. Boder
- Department of Chemical and Biomolecular Engineering, University of Tennessee, Knoxville, TN 37996, USA
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