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Fever as an evolutionary agent to select immune complexes interfaces. Immunogenetics 2022; 74:465-474. [PMID: 35545703 PMCID: PMC9094598 DOI: 10.1007/s00251-022-01263-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2022] [Accepted: 04/08/2022] [Indexed: 11/10/2022]
Abstract
We herein analyzed all available protein–protein interfaces of the immune complexes from the Protein Data Bank whose antigens belong to pathogens or cancers that are modulated by fever in mammalian hosts. We also included, for comparison, protein interfaces from immune complexes that are not significantly modulated by the fever response. We highlight the distribution of amino acids at these viral, bacterial, protozoan and cancer epitopes, and at their corresponding paratopes that belong strictly to monoclonal antibodies. We identify the “hotspots”, i.e. residues that are highly connected at such interfaces, and assess the structural, kinetic and thermodynamic parameters responsible for complex formation. We argue for an evolutionary pressure for the types of residues at these protein interfaces that may explain the role of fever as a selective force for optimizing antibody binding to antigens.
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Dao M, MacDonald I, Asaro RJ. Erythrocyte flow through the interendothelial slits of the splenic venous sinus. Biomech Model Mechanobiol 2021; 20:2227-2245. [PMID: 34535857 DOI: 10.1007/s10237-021-01503-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2021] [Accepted: 07/12/2021] [Indexed: 10/20/2022]
Abstract
The flow patterns of red blood cells through the spleen are intimately linked to clearance of senescent RBCs, with clearance principally occurring within the open flow through the red pulp and slits of the venous sinus system that exists in humans, rats, and dogs. Passage through interendothelial slits (IESs) of the sinus has been shown by MacDonald et al. (Microvasc Res 33:118-134, 1987) to be mediated by the caliber, i.e., slit opening width, of these slits. IES caliber within a given slit of a given sinus section has been shown to operate in an asynchronous manner. Here, we describe a model and simulation results that demonstrate how the supporting forces exerted on the sinus by the reticular meshwork of the red pulp, combined with asymmetrical contractility of stress fibers within the endothelial cells comprising the sinus, describe this vital and intriguing behavior. These results shed light on the function of the sinus slits in species such as humans, rats, and dogs that possess sinusoidal sinuses. Instead of assuming a passive mechanical filtering mechanism of the IESs, our proposed model provides a mechanically consistent explanation for the dynamically modulated IES opening/filtering mechanism observed in vivo. The overall perspective provided is also consistent with the view that IES passage serves as a self-protective mechanism in RBC vesiculation and inclusion removal.
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Affiliation(s)
- Ming Dao
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
| | - Ian MacDonald
- Department of Medical Biophysics, Schulich School of Medicine and Dentistry Western University, London, ON, Canada
| | - R J Asaro
- Department of Structural Engineering, University of California, San Diego, La Jolla, CA, 92093, USA.
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Fröhlich B, Dasanna AK, Lansche C, Czajor J, Sanchez CP, Cyrklaff M, Yamamoto A, Craig A, Schwarz US, Lanzer M, Tanaka M. Functionalized supported membranes for quantifying adhesion of P. falciparum-infected erythrocytes. Biophys J 2021; 120:3315-3328. [PMID: 34246628 PMCID: PMC8391081 DOI: 10.1016/j.bpj.2021.07.003] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2021] [Revised: 06/21/2021] [Accepted: 07/02/2021] [Indexed: 12/22/2022] Open
Abstract
The pathology of Plasmodium falciparum malaria is largely defined by the cytoadhesion of infected erythrocytes to the microvascular endothelial lining. The complexity of the endothelial surface and the large range of interactions available for the infected erythrocyte via parasite-encoded adhesins make analysis of critical contributions during cytoadherence challenging to define. Here, we have explored supported membranes functionalized with two important adhesion receptors, ICAM1 or CD36, as a quantitative biomimetic surface to help understand the processes involved in cytoadherence. Parasitized erythrocytes bound to the receptor-functionalized membranes with high efficiency and selectivity under both static and flow conditions, with infected wild-type erythrocytes displaying a higher binding capacity than do parasitized heterozygous sickle cells. We further show that the binding efficiency decreased with increasing intermolecular receptor distance and that the cell-surface contacts were highly dynamic and increased with rising wall shear stress as the cell underwent a shape transition. Computer simulations using a deformable cell model explained the wall-shear-stress-induced dynamic changes in cell shape and contact area via the specific physical properties of erythrocytes, the density of adhesins presenting knobs, and the lateral movement of receptors in the supported membrane.
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Affiliation(s)
- Benjamin Fröhlich
- Physical Chemistry of Biosystems, Institute of Physical Chemistry, Heidelberg, Germany
| | - Anil K Dasanna
- Institute for Theoretical Physics and BioQuant-Center for Quantitative Biology, Heidelberg University, Heidelberg, Germany
| | - Christine Lansche
- Department of Infectious Diseases, Parasitology, Universitätsklinikum Heidelberg, Heidelberg, Germany
| | - Julian Czajor
- Physical Chemistry of Biosystems, Institute of Physical Chemistry, Heidelberg, Germany
| | - Cecilia P Sanchez
- Department of Infectious Diseases, Parasitology, Universitätsklinikum Heidelberg, Heidelberg, Germany
| | - Marek Cyrklaff
- Department of Infectious Diseases, Parasitology, Universitätsklinikum Heidelberg, Heidelberg, Germany
| | - Akihisa Yamamoto
- Center for Integrative Medicine and Physics, Institute for Advanced Study, Kyoto University, Kyoto, Japan
| | - Alister Craig
- Liverpool School of Tropical Medicine, Liverpool, United Kingdom
| | - Ulrich S Schwarz
- Institute for Theoretical Physics and BioQuant-Center for Quantitative Biology, Heidelberg University, Heidelberg, Germany.
| | - Michael Lanzer
- Department of Infectious Diseases, Parasitology, Universitätsklinikum Heidelberg, Heidelberg, Germany.
| | - Motomu Tanaka
- Physical Chemistry of Biosystems, Institute of Physical Chemistry, Heidelberg, Germany; Center for Integrative Medicine and Physics, Institute for Advanced Study, Kyoto University, Kyoto, Japan.
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Alvarez DR, Ospina A, Barwell T, Zheng B, Dey A, Li C, Basu S, Shi X, Kadri S, Chakrabarti K. The RNA structurome in the asexual blood stages of malaria pathogen plasmodium falciparum. RNA Biol 2021; 18:2480-2497. [PMID: 33960872 DOI: 10.1080/15476286.2021.1926747] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022] Open
Abstract
Plasmodium falciparum is a deadly human pathogen responsible for the devastating disease called malaria. In this study, we measured the differential accumulation of RNA secondary structures in coding and non-coding transcripts from the asexual developmental cycle in P. falciparum in human red blood cells. Our comprehensive analysis that combined high-throughput nuclease mapping of RNA structures by duplex RNA-seq, SHAPE-directed RNA structure validation, immunoaffinity purification and characterization of antisense RNAs collectively measured differentially base-paired RNA regions throughout the parasite's asexual RBC cycle. Our mapping data not only aligned to a diverse pool of RNAs with known structures but also enabled us to identify new structural RNA regions in the malaria genome. On average, approximately 71% of the genes with secondary structures are found to be protein coding mRNAs. The mapping pattern of these base-paired RNAs corresponded to all regions of mRNAs, including the 5' UTR, CDS and 3' UTR as well as the start and stop codons. Histone family genes which are known to form secondary structures in their mRNAs and transcripts from genes which are important for transcriptional and post-transcriptional control, such as the unique plant-like transcription factor family, ApiAP2, DNA-/RNA-binding protein, Alba3 and proteins important for RBC invasion and malaria cytoadherence also showed strong accumulation of duplex RNA reads in various asexual stages in P. falciparum. Intriguingly, our study determined stage-specific, dynamic relationships between mRNA structural contents and translation efficiency in P. falciparum asexual blood stages, suggesting an essential role of RNA structural changes in malaria gene expression programs.
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Affiliation(s)
- Diana Renteria Alvarez
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, North Carolina, USA
| | - Alejandra Ospina
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, North Carolina, USA
| | - Tiffany Barwell
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, North Carolina, USA
| | - Bo Zheng
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, North Carolina, USA
| | - Abhishek Dey
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, North Carolina, USA
| | - Chong Li
- Temple University, Philadelphia, PA, USA
| | - Shrabani Basu
- Division of Medical Genetics, Children's Hospital of Pittsburgh of UPMC, Pittsburgh, PA, USA
| | | | - Sabah Kadri
- Division of Health and Biomedical Informatics, Northwestern University Feinberg School of Medicine and Ann & Robert H. Lurie Children's Hospital of Chicago, Chicago, IL, USA
| | - Kausik Chakrabarti
- Department of Biological Sciences, University of North Carolina at Charlotte, Charlotte, North Carolina, USA
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