1
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Angata T, Varki A. Discovery, classification, evolution and diversity of Siglecs. Mol Aspects Med 2023; 90:101117. [PMID: 35989204 PMCID: PMC9905256 DOI: 10.1016/j.mam.2022.101117] [Citation(s) in RCA: 11] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2022] [Revised: 08/03/2022] [Accepted: 08/06/2022] [Indexed: 02/08/2023]
Abstract
Immunoglobulin (Ig) superfamily proteins play diverse roles in vertebrates, including regulation of cellular responses by sensing endogenous or exogenous ligands. Siglecs are a family of glycan-recognizing proteins belonging to the Ig superfamily (i.e., I-type lectins). Siglecs are expressed on various leukocyte types and are involved in diverse aspects of immunity, including the regulation of inflammatory responses, leukocyte proliferation, host-microbe interaction, and cancer immunity. Sialoadhesin/Siglec-1, CD22/Siglec-2, and myelin-associated glycoprotein/Siglec-4 were among the first to be characterized as members of the Siglec family, and along with Siglec-15, they are relatively well-conserved among tetrapods. Conversely, CD33/Siglec-3-related Siglecs (CD33rSiglecs, so named as they show high sequence similarity with CD33/Siglec-3) are encoded in a gene cluster with many interspecies variations and even intraspecies variations within some lineages such as humans. The rapid evolution of CD33rSiglecs expressed on leukocytes involved in innate immunity likely reflects the selective pressure by pathogens that interact and possibly exploit these Siglecs. Human Siglecs have several additional unique and/or polymorphic properties as compared with closely related great apes, changes possibly related to the loss of the sialic acid Neu5Gc, another distinctly human event in sialobiology. Multiple changes in human CD33rSiglecs compared to great apes include many examples of human-specific expression in non-immune cells, coinciding with human-specific diseases involving such cell types. Some Siglec gene polymorphisms have dual consequences-beneficial in a situation but detrimental in another. The association of human Siglec gene polymorphisms with several infectious and non-infectious diseases likely reflects the ongoing competition between the host and microbial pathogens.
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Affiliation(s)
- Takashi Angata
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan; Institute of Biochemical Sciences, National Taiwan University, Taipei, Taiwan.
| | - Ajit Varki
- Department of Cellular and Molecular Medicine, School of Medicine, University of California, San Diego, La Jolla, CA, USA.
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2
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Läubli H, Nalle SC, Maslyar D. Targeting the Siglec-Sialic Acid Immune Axis in Cancer: Current and Future Approaches. Cancer Immunol Res 2022; 10:1423-1432. [PMID: 36264237 PMCID: PMC9716255 DOI: 10.1158/2326-6066.cir-22-0366] [Citation(s) in RCA: 23] [Impact Index Per Article: 11.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2022] [Revised: 07/08/2022] [Accepted: 09/01/2022] [Indexed: 01/10/2023]
Abstract
The sialic acid-binding immunoglobulin-like lectin (Siglec)-sialic acid immune axis is an evolutionarily conserved immunoregulatory pathway that provides a mechanism for establishing self-recognition and combatting invasive pathogens. Perturbations in the pathway lead to many immune dysregulated diseases, including autoimmunity, neurodegeneration, allergic conditions, and cancer. The purpose of this review is to provide a brief overview of the relationship between Siglecs and sialic acid as they relate to human health and disease, to consider current Siglec-based therapeutics, and to discuss new therapeutic approaches targeting the Siglec-sialic acid immune axis, with a focus on cancer.
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Affiliation(s)
- Heinz Läubli
- Laboratory for Cancer Immunotherapy, Department of Biomedicine, University, of Basel, Basel, Switzerland.,Division of Oncology, University Hospital Basel, Basel, Switzerland.,Corresponding Author: Heinz Läubli, University Hospital Basel, Petersgraben 4, Basel 4031, Switzerland. Phone: 416-1556-5212; Fax: 416-1265-5316; E-mail:
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3
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Grabenstein S, Barnard KN, Anim M, Armoo A, Weichert WS, Bertozzi CR, Parrish CR, Willand-Charnley R. Deacetylated sialic acids modulates immune mediated cytotoxicity via the sialic acid-Siglec pathway. Glycobiology 2021; 31:1279-1294. [PMID: 34192335 DOI: 10.1093/glycob/cwab068] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2020] [Revised: 06/09/2021] [Accepted: 06/20/2021] [Indexed: 12/11/2022] Open
Abstract
Cancers utilize glycans to evade the immune system via the Sialic acid (Sia)-Siglec (Sialic-acid-binding immunoglobulin-like lectins) pathway. Specifically, atypical structural forms of sialic acid bind to inhibitory Siglec receptors on Natural Killer (NK) cells resulting in the suppression of immune cell mediated cytotoxicity. The mechanism of action that governs the Sia-Siglec pathway in cancers is not understood. Specifically, how deviations from the typical form of Sia mechanistically contribute. Here we focused on modulating 9-O and 7,9-O-acetylation of Neu5Ac, via CRISPR-Cas9 gene editing, a functional group that is absent from Sias on many types of cancer cells. The two genes that are responsible for regulating the level of acetylation on Neu5Ac, are Sialic acid acetylesterase (SIAE) and Sialic acid acetyltransferase (CASD1). These genes modulated Siglec binding in colon, lung, and a non-cancerous kidney cell line. In the absence of SIAE, Neu5Ac is acetylated, engagement of cancer associated Siglecs is reduced while binding was increased when the ability to acetylate was removed via CASD1 knock out. In the absence of SIAE NK mediated cytotoxicity increased in both colon and lung cancer cells. In addition to modulating Siglec binding, SIAE expression modulates the level of Sias in a cell, and the α2-6-linkage of Sias - which is specifically upregulated and associated with cancers. Uncovering how functional group alterations on Neu5Ac contribute mechanistically to both Siglec receptor binding, the Sia-Siglec immune evasion pathway, and the production of cancer associated glycosidic linkages -offers a promising avenue for targeted cancer immune therapies in the future.
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Affiliation(s)
- Susan Grabenstein
- Department of Chemistry & Biochemistry, South Dakota State University, Brookings, SD 57007
| | - Karen N Barnard
- Basic Sciences Division, Fred Hutchinson Cancer Research Center, Seattle WA, 98109
| | - Mathias Anim
- Department of Chemistry & Biochemistry, South Dakota State University, Brookings, SD 57007
| | - Albert Armoo
- Department of Chemistry & Biochemistry, South Dakota State University, Brookings, SD 57007
| | - Wendy S Weichert
- Baker Institute for Animal Health, Department of Microbiology and Immunology College of Veterinary Medicine, Cornell University, Ithaca, NY 14853
| | - Carolyn R Bertozzi
- Department of Chemistry, Stanford University, Stanford, CA 94305.,Howard Hughes Medical Institute, Stanford University, Stanford, CA, USA
| | - Colin R Parrish
- Baker Institute for Animal Health, Department of Microbiology and Immunology College of Veterinary Medicine, Cornell University, Ithaca, NY 14853
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4
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Läubli H, Kawanishi K, George Vazhappilly C, Matar R, Merheb M, Sarwar Siddiqui S. Tools to study and target the Siglec-sialic acid axis in cancer. FEBS J 2020; 288:6206-6225. [PMID: 33251699 DOI: 10.1111/febs.15647] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2020] [Revised: 11/18/2020] [Accepted: 11/23/2020] [Indexed: 12/16/2022]
Abstract
Siglecs are widely expressed on leucocytes and bind to ubiquitously presented glycans containing sialic acids (sialoglycans). Most Siglecs carry an immunoreceptor tyrosine-based inhibition motif (ITIM) and elicit an inhibitory intracellular signal upon ligand binding. A few Siglec receptors can, however, recruit immunoreceptor tyrosine-based activation motif (ITAM)-containing factors, which activate cells. The role of hypersialylation (the enhanced expression of sialoglycans) has recently been explored in cancer progression. Mechanistic studies have shown that hypersialylation on cancer cells can engage inhibitory Siglecs on the surface of immune cells and induce immunosuppression. These recent studies strongly suggest that the Siglec-sialic acid axis can act as a potential target for cancer immunotherapy. Moreover, the use of new tools and techniques is facilitating these studies. In this review, we summarise techniques used to study Siglecs, including different mouse models, monoclonal antibodies, Siglec fusion proteins, and sialoglycan arrays. Furthermore, we discuss the recent major developments in the study of Siglecs in cancer immunosuppression, tools, and techniques used in targeting the Siglec-sialic acid axis and the possibility of clinical intervention.
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Affiliation(s)
- Heinz Läubli
- Laboratory for Cancer Immunotherapy, Department of Biomedicine, and Medical Oncology, Department of Internal Medicine, University Hospital Basel, Switzerland
| | - Kunio Kawanishi
- Kidney and Vascular Pathology, University of Tsukuba, Ibaraki, Japan
| | | | - Rachel Matar
- Department of Biotechnology, American University of Ras Al Khaimah (AURAK), UAE
| | - Maxime Merheb
- Department of Biotechnology, American University of Ras Al Khaimah (AURAK), UAE
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5
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Martins TA, Schmassmann P, Shekarian T, Boulay JL, Ritz MF, Zanganeh S, Vom Berg J, Hutter G. Microglia-Centered Combinatorial Strategies Against Glioblastoma. Front Immunol 2020; 11:571951. [PMID: 33117364 PMCID: PMC7552736 DOI: 10.3389/fimmu.2020.571951] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2020] [Accepted: 08/26/2020] [Indexed: 12/13/2022] Open
Abstract
Tumor-associated microglia (MG) and macrophages (MΦ) are important components of the glioblastoma (GBM) immune tumor microenvironment (iTME). From the recent advances in understanding how MG and GBM cells evolve and interact during tumorigenesis, we emphasize the cooperation of MG with other immune cell types of the GBM-iTME, mainly MΦ and T cells. We provide a comprehensive overview of current immunotherapeutic clinical trials and approaches for the treatment of GBM, which in general, underestimate the counteracting contribution of immunosuppressive MG as a main factor for treatment failure. Furthermore, we summarize new developments and strategies in MG reprogramming/re-education in the GBM context, with a focus on ways to boost MG-mediated tumor cell phagocytosis and associated experimental models and methods. This ultimately converges in our proposal of novel combinatorial regimens that locally modulate MG as a central paradigm, and therefore may lead to additional, long-lasting, and effective tumoricidal responses.
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Affiliation(s)
- Tomás A Martins
- Department of Biomedicine, University of Basel, Basel, Switzerland
| | | | - Tala Shekarian
- Department of Biomedicine, University of Basel, Basel, Switzerland
| | - Jean-Louis Boulay
- Department of Biomedicine, University of Basel, Basel, Switzerland.,Department of Neurosurgery, University Hospital Basel, Basel, Switzerland
| | - Marie-Françoise Ritz
- Department of Biomedicine, University of Basel, Basel, Switzerland.,Department of Neurosurgery, University Hospital Basel, Basel, Switzerland
| | - Steven Zanganeh
- Sloan Kettering Institute, Memorial Sloan Kettering Cancer Center, New York, NY, United States.,Department of Chemical and Biomolecular Engineering, New York University, New York, NY, United States
| | - Johannes Vom Berg
- Institute of Laboratory Animal Science, University of Zurich, Schlieren, Switzerland
| | - Gregor Hutter
- Department of Biomedicine, University of Basel, Basel, Switzerland.,Department of Neurosurgery, University Hospital Basel, Basel, Switzerland
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6
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Bandala-Sanchez E, Bediaga NG, Naselli G, Neale AM, Harrison LC. Siglec-10 expression is up-regulated in activated human CD4 + T cells. Hum Immunol 2020; 81:101-104. [PMID: 32046870 DOI: 10.1016/j.humimm.2020.01.009] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2019] [Revised: 01/09/2020] [Accepted: 01/24/2020] [Indexed: 02/05/2023]
Abstract
Most sialic acid-binding immunoglobulin-like lectins (Siglecs) suppress immune cell function but are expressed at low levels on human T cells. We found that soluble CD52 inhibited T cell signalling by ligating Siglec-10, but the presence of Siglec-10 on human T cells has been questioned. To address this concern, we examined the expression of Siglec-10 at the RNA and protein level in human CD4+ T cells. Analysis by RNAseq, qPCR and flow cytometry demonstrated that, in contrast to other Siglecs, after activation of CD4+ T cells Siglec-10 was selectively upregulated in a subset of cells also high for CD52 expression. This observation is consistent with a homeostatic role for Siglec-10 in human CD4+ T cells.
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Affiliation(s)
- E Bandala-Sanchez
- Walter and Eliza Hall Institute of Medical Research, Parkville 3052, Victoria, Australia; Department of Medical Biology, University of Melbourne, Parkville 3052, Victoria, Australia
| | - N G Bediaga
- Walter and Eliza Hall Institute of Medical Research, Parkville 3052, Victoria, Australia; Department of Medical Biology, University of Melbourne, Parkville 3052, Victoria, Australia
| | - G Naselli
- Walter and Eliza Hall Institute of Medical Research, Parkville 3052, Victoria, Australia; Department of Medical Biology, University of Melbourne, Parkville 3052, Victoria, Australia
| | - A M Neale
- Walter and Eliza Hall Institute of Medical Research, Parkville 3052, Victoria, Australia; Department of Medical Biology, University of Melbourne, Parkville 3052, Victoria, Australia
| | - L C Harrison
- Walter and Eliza Hall Institute of Medical Research, Parkville 3052, Victoria, Australia; Department of Medical Biology, University of Melbourne, Parkville 3052, Victoria, Australia.
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7
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Läubli H, Varki A. Sialic acid-binding immunoglobulin-like lectins (Siglecs) detect self-associated molecular patterns to regulate immune responses. Cell Mol Life Sci 2020; 77:593-605. [PMID: 31485715 PMCID: PMC7942692 DOI: 10.1007/s00018-019-03288-x] [Citation(s) in RCA: 102] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2019] [Revised: 08/11/2019] [Accepted: 08/28/2019] [Indexed: 12/12/2022]
Abstract
The mammalian immune system evolved to tightly regulate the elimination of pathogenic microbes and neoplastic transformed cells while tolerating our own healthy cells. Here, we summarize experimental evidence for the role of Siglecs-in particular CD33-related Siglecs-as self-receptors and their sialoglycan ligands in regulating this balance between recognition of self and non-self. Sialoglycans are found in the glycocalyx and extracellular fluids and matrices of all mammalian cells and can be considered as self-associated molecular patterns (SAMPs). We also provide an overview of the known interactions of Siglec receptors and sialoglycan-SAMPs. Manipulation of the Siglec-SAMP axis offers new therapeutic opportunities for the treatment of inflammatory conditions, autoimmune diseases and also cancer immunotherapy.
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Affiliation(s)
- Heinz Läubli
- Laboratory for Cancer Immunotherapy, University Hospital Basel, Petersgraben 4, 4031, Basel, Switzerland.
| | - Ajit Varki
- Department of Medicine, Glycobiology Research and Training Center, University of California, San Diego, La Jolla, CA, 92093-0687, USA.
- Department of Cellular and Molecular Medicine, Glycobiology Research and Training Center, University of California, San Diego, La Jolla, CA, 92093-0687, USA.
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Bärenwaldt A, Läubli H. The sialoglycan-Siglec glyco-immune checkpoint - a target for improving innate and adaptive anti-cancer immunity. Expert Opin Ther Targets 2019; 23:839-853. [PMID: 31524529 DOI: 10.1080/14728222.2019.1667977] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Introduction: During cancer progression, tumor cells develop several mechanisms to prevent killing and to shape the immune system into a tumor-promoting environment. One of such regulatory mechanism is the overexpression of sialic acid (Sia) on carbohydrates of proteins and lipids on tumor cells. Sia-containing glycans or sialoglycans were shown to inhibit immune effector functions of NK cells and T cells by engaging inhibitory Siglec receptors on the surface of these cells. They can also modulate the differentiation of myeloid cells into tumor-promoting M2 macrophages. Areas covered: We review the role of sialoglycans in cancer and introduce the Siglecs, their expression on different immune cells and their interaction with cancer-associated sialoglycans. The targeting of this sialoglycan-Siglec glyco-immune checkpoint is discussed along with potential therapeutic approaches. Pubmed was searched for publications on Siglecs, sialic acid, and cancer. Expert opinion: The targeting of sialoglycan-Siglec interactions has become a major focus in cancer research. New approaches have been developed that directly target sialic acids in tumor lesions. Targeted sialidases that cleave sialic acid specifically in the tumor, have already shown efficacy; efforts targeting the sialoglycan-Siglec pathway for improvement of CAR T cell therapy are ongoing. The sialoglycan-Siglec immune checkpoint is a promising new target for cancer immunotherapy.
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Affiliation(s)
- Anne Bärenwaldt
- Division of Medical Oncology, and Laboratory for Cancer Immunotherapy, Department of Biomedicine, University Hospital Basel , Basel , Switzerland
| | - Heinz Läubli
- Division of Medical Oncology, and Laboratory for Cancer Immunotherapy, Department of Biomedicine, University Hospital Basel , Basel , Switzerland
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Läubli H, Borsig L. Altered Cell Adhesion and Glycosylation Promote Cancer Immune Suppression and Metastasis. Front Immunol 2019; 10:2120. [PMID: 31552050 PMCID: PMC6743365 DOI: 10.3389/fimmu.2019.02120] [Citation(s) in RCA: 153] [Impact Index Per Article: 30.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2019] [Accepted: 08/23/2019] [Indexed: 12/14/2022] Open
Abstract
Cell-cell interactions and cell adhesion are key mediators of cancer progression and facilitate hallmarks of cancer including immune evasion and metastatic dissemination. Many cell adhesion molecules within the tumor microenvironment are changed and significant alterations of glycosylation are observed. These changes in cell adhesion molecules alter the ability of tumor cells to interact with other cells and extracellular matrix proteins. Three families of cell-cell interaction molecules selectins, Siglecs, and integrins have been associated with cancer progression in many pre-clinical studies, yet inhibition of cell adhesion as a therapeutic target is just beginning to be explored. We review how cell-cell interactions mediated by integrins and the glycan-binding receptors selectins and Siglec receptors support cancer progression. The discussion focuses on mechanisms during immune evasion and metastasis that can be therapeutically targeted by blocking these cell-cell interactions.
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Affiliation(s)
- Heinz Läubli
- Laboratory for Cancer Immunotherapy, Department of Biomedicine and Medical Oncology, Department of Internal Medicine, University Hospital, Basel, Switzerland
| | - Lubor Borsig
- Department of Physiology, University of Zurich, Zurich, Switzerland.,Comprehensive Cancer Center, Zurich, Switzerland
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10
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Kargar M, Jamali H, Sadeghi M. Investigating Association of Human-Specific Derived Alleles of CD33 and Other Genes with Lifespan of Iranians. MEDICAL LABORATORY JOURNAL 2019. [DOI: 10.29252/mlj.13.5.19] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
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11
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Estus S, Shaw BC, Devanney N, Katsumata Y, Press EE, Fardo DW. Evaluation of CD33 as a genetic risk factor for Alzheimer's disease. Acta Neuropathol 2019; 138:187-199. [PMID: 30949760 PMCID: PMC7035471 DOI: 10.1007/s00401-019-02000-4] [Citation(s) in RCA: 51] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Revised: 03/22/2019] [Accepted: 03/30/2019] [Indexed: 12/23/2022]
Abstract
In 2011, genome-wide association studies implicated a polymorphism near CD33 as a genetic risk factor for Alzheimer's disease. This finding sparked interest in this member of the sialic acid-binding immunoglobulin-type lectin family which is linked to innate immunity. Subsequent studies found that CD33 is expressed in microglia in the brain and then investigated the molecular mechanism underlying the CD33 genetic association with Alzheimer's disease. The allele that protects from Alzheimer's disease acts predominately to increase a CD33 isoform lacking exon 2 at the expense of the prototypic, full-length CD33 that contains exon 2. Since this exon encodes the sialic acid ligand-binding domain, the finding that the loss of exon 2 was associated with decreased Alzheimer's disease risk was interpreted as meaning that a decrease in functional CD33 and its associated immune suppression was protective from Alzheimer's disease. However, this interpretation may need to be reconsidered given current findings that a genetic deletion which abrogates CD33 is not associated with Alzheimer's disease risk. Therefore, integrating currently available findings leads us to propose a model wherein the CD33 isoform lacking the ligand-binding domain represents a gain of function variant that reduces Alzheimer's disease risk.
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Affiliation(s)
- Steven Estus
- Department of Physiology and Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, USA.
| | - Benjamin C Shaw
- Department of Physiology and Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, USA
| | - Nicholas Devanney
- Department of Physiology and Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, USA
| | - Yuriko Katsumata
- Department of Biostatistics and Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, USA
| | | | - David W Fardo
- Department of Biostatistics and Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, USA
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12
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Landig CS, Hazel A, Kellman BP, Fong JJ, Schwarz F, Agarwal S, Varki N, Massari P, Lewis NE, Ram S, Varki A. Evolution of the exclusively human pathogen Neisseria gonorrhoeae: Human-specific engagement of immunoregulatory Siglecs. Evol Appl 2019; 12:337-349. [PMID: 30697344 PMCID: PMC6346652 DOI: 10.1111/eva.12744] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2018] [Accepted: 11/14/2018] [Indexed: 12/18/2022] Open
Abstract
Neisseria gonorrhoeae causes the sexually transmitted disease gonorrhea exclusively in humans and uses multiple strategies to infect, including acquisition of host sialic acids that cap and mask lipooligosaccharide termini, while restricting complement activation. We hypothesized that gonococci selectively target human anti-inflammatory sialic acid-recognizing Siglec receptors on innate immune cells to blunt host responses and that pro-inflammatory Siglecs and SIGLEC pseudogene polymorphisms represent host evolutionary adaptations to counteract this interaction. N. gonorrhoeae can indeed engage multiple human but not chimpanzee CD33rSiglecs expressed on innate immune cells and in the genitourinary tract--including Siglec-11 (inhibitory) and Siglec-16 (activating), which we detected for the first time on human cervical epithelium. Surprisingly, in addition to LOS sialic acid, we found that gonococcal porin (PorB) mediated binding to multiple Siglecs. PorB also bound preferentially to human Siglecs and not chimpanzee orthologs, modulating host immune reactions in a human-specific manner. Lastly, we studied the distribution of null SIGLEC polymorphisms in a Namibian cohort with a high prevalence of gonorrhea and found that uninfected women preferentially harbor functional SIGLEC16 alleles encoding an activating immune receptor. These results contribute to the understanding of the human specificity of N. gonorrhoeae and how it evolved to evade the human immune defense.
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Affiliation(s)
- Corinna S. Landig
- Glycobiology Research and Training CenterUniversity of California, San DiegoLa JollaCalifornia
- Department of Cellular and Molecular MedicineUniversity of California, San DiegoLa JollaCalifornia
- Department of MedicineUniversity of California, San DiegoLa JollaCalifornia
| | - Ashley Hazel
- Department of Earth System ScienceStanford UniversityStanfordCalifornia
| | - Benjamin P. Kellman
- Department of PediatricsUniversity of California, San DiegoLa JollaCalifornia
- Bioinformatics and Systems Biology Graduate ProgramUniversity of California, San DiegoLa JollaCalifornia
| | - Jerry J. Fong
- Glycobiology Research and Training CenterUniversity of California, San DiegoLa JollaCalifornia
- Department of Cellular and Molecular MedicineUniversity of California, San DiegoLa JollaCalifornia
- Department of MedicineUniversity of California, San DiegoLa JollaCalifornia
| | - Flavio Schwarz
- Glycobiology Research and Training CenterUniversity of California, San DiegoLa JollaCalifornia
- Department of Cellular and Molecular MedicineUniversity of California, San DiegoLa JollaCalifornia
- Department of MedicineUniversity of California, San DiegoLa JollaCalifornia
| | - Sarika Agarwal
- Department of MedicineUniversity of Massachusetts Medical SchoolWorcesterMassachusetts
| | - Nissi Varki
- Glycobiology Research and Training CenterUniversity of California, San DiegoLa JollaCalifornia
- Department of PathologyUniversity of California, San DiegoLa JollaCalifornia
| | - Paola Massari
- Department of ImmunologyTufts University School of MedicineBostonMassachusetts
| | - Nathan E. Lewis
- Department of PediatricsUniversity of California, San DiegoLa JollaCalifornia
- Bioinformatics and Systems Biology Graduate ProgramUniversity of California, San DiegoLa JollaCalifornia
- Novo Nordisk Foundation Center for BiosustainabilityUniversity of California, San DiegoLa JollaCalifornia
| | - Sanjay Ram
- Department of MedicineUniversity of Massachusetts Medical SchoolWorcesterMassachusetts
| | - Ajit Varki
- Glycobiology Research and Training CenterUniversity of California, San DiegoLa JollaCalifornia
- Department of Cellular and Molecular MedicineUniversity of California, San DiegoLa JollaCalifornia
- Department of MedicineUniversity of California, San DiegoLa JollaCalifornia
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Adams OJ, Stanczak MA, von Gunten S, Läubli H. Targeting sialic acid-Siglec interactions to reverse immune suppression in cancer. Glycobiology 2018; 28:640-647. [PMID: 29309569 DOI: 10.1093/glycob/cwx108] [Citation(s) in RCA: 65] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2017] [Accepted: 12/19/2017] [Indexed: 12/17/2022] Open
Abstract
Changes in sialic acids in cancer have been observed for many years. In particular, the increase of sialoglycan density or hypersialylation in tumors has been described. Recent studies have identified mechanisms for immune evasion based on sialoglycan interactions with immunoregulatory Siglec receptors that are exploited by tumor cells and microorganisms alike. Siglecs are mostly inhibitory receptors similar to known immune checkpoints including PD-1 or CTLA-4 that are successfully targeted with blocking antibodies for cancer immunotherapy. Here, we summarize the known changes of sialic acids in cancer and the role Siglec receptors play in cancer immunity. We also focus on potential ways to target these Siglec receptors or sialoglycans in order to improve anti-cancer immunity.
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Affiliation(s)
- Olivia Joan Adams
- Institute of Pharmacology, University of Bern, Inselspital INO-F, Bern, Switzerland
| | | | - Stephan von Gunten
- Institute of Pharmacology, University of Bern, Inselspital INO-F, Bern, Switzerland
| | - Heinz Läubli
- Laboratory of Cancer Immunology, Department of Biomedicine.,Medical Oncology, Department of Internal Medicine, University Hospital Basel, Petersgraben 4, Basel, Switzerland
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Bisht K, Sharma K, Tremblay MÈ. Chronic stress as a risk factor for Alzheimer's disease: Roles of microglia-mediated synaptic remodeling, inflammation, and oxidative stress. Neurobiol Stress 2018; 9:9-21. [PMID: 29992181 PMCID: PMC6035903 DOI: 10.1016/j.ynstr.2018.05.003] [Citation(s) in RCA: 223] [Impact Index Per Article: 37.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2018] [Revised: 02/23/2018] [Accepted: 05/14/2018] [Indexed: 02/07/2023] Open
Abstract
Microglia are the predominant immune cells of the central nervous system (CNS) that exert key physiological roles required for maintaining CNS homeostasis, notably in response to chronic stress, as well as mediating synaptic plasticity, learning and memory. The repeated exposure to stress confers a higher risk of developing neurodegenerative diseases including sporadic Alzheimer's disease (AD). While microglia have been causally linked to amyloid beta (Aβ) accumulation, tau pathology, neurodegeneration, and synaptic loss in AD, they were also attributed beneficial roles, notably in the phagocytic elimination of Aβ. In this review, we discuss the interactions between chronic stress and AD pathology, overview the roles played by microglia in AD, especially focusing on chronic stress as an environmental risk factor modulating their function, and present recently-described microglial phenotypes associated with neuroprotection in AD. These microglial phenotypes observed under both chronic stress and AD pathology may provide novel opportunities for the development of better-targeted therapeutic interventions.
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Key Words
- ABCA7, ATP-binding cassette transporter A7
- AD, Alzheimer's disease
- APOE, Apolipoprotein E
- APP, amyloid precursor protein
- Alzheimer's disease
- Aβ, Amyloid beta
- BDNF, brain derived neurotrophic factor
- CD11b, cluster of differentiation molecule 11B
- CD33, cluster of differentiation 33
- CNS, central nervous system
- CR, complement receptor
- CRF, corticotropin releasing factor
- DAM, disease associated microglia
- DAP12, DNAX-activation protein 12
- Dark microglia
- FAD, Familial Alzheimer's disease
- FCRLS, Fc receptor-like S scavenger receptor
- GR, glucocorticoid receptor
- HPA axis, hypothalamic pituitary adrenocortical axis
- IBA1, ionized calcium-binding adapter molecule 1
- IL, interleukin
- LTP, long-term potentiation
- MGnD, microglia with a neurodegenerative phenotype
- MR, mineralocorticoid receptor
- Microglia
- Microglial phenotypes
- NADPH, nicotinamide adenine dinucleotide phosphate
- NFT, neurofibrillary tangles
- Neurodegeneration
- Neuroinflammation
- PS, presenilin
- ROS, reactive oxygen species
- Stress
- Synaptic remodeling
- TGFβ, transforming growth factor β
- TLR, Toll-like receptors
- TMEM119, transmembrane protein 119
- TNFα, tumor necrosis factor-α
- TREM2, triggering receptor expressed in myeloid cells 2
- TYROBP, TYRO protein tyrosine kinase binding protein
- mPFC, medial prefrontal cortex
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Affiliation(s)
- Kanchan Bisht
- Axe Neurosciences, CRCHU de Québec-Université Laval, Québec, QC, Canada
| | - Kaushik Sharma
- Axe Neurosciences, CRCHU de Québec-Université Laval, Québec, QC, Canada
| | - Marie-Ève Tremblay
- Axe Neurosciences, CRCHU de Québec-Université Laval, Québec, QC, Canada
- Département de médecine moléculaire, Université Laval, Québec, QC, Canada
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15
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Fong JJ, Tsai CM, Saha S, Nizet V, Varki A, Bui JD. Siglec-7 engagement by GBS β-protein suppresses pyroptotic cell death of natural killer cells. Proc Natl Acad Sci U S A 2018; 115:10410-10415. [PMID: 30254166 PMCID: PMC6187154 DOI: 10.1073/pnas.1804108115] [Citation(s) in RCA: 30] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Natural killer (NK) cells are innate immune lymphocytes that recognize and destroy abnormal host cells, such as tumor cells or those infected by viral pathogens. To safely accomplish these functions, NK cells display activating receptors that detect stress molecules or viral ligands displayed at the cell surface, balanced by inhibitory receptors that bind to self-molecules. To date, such activating and inhibitory receptors on NK cells are not known to recognize bacterial determinants. Moreover, NK cell responses to direct interactions with extracellular bacteria are poorly explored. In this study, we observed the human neonatal pathogen group B Streptococcus (GBS) can directly engage human NK cells. The interaction was mediated through the B6N segment of streptococcal β-protein, binding to the inhibitory receptor Siglec-7 via its amino-terminal V-set domain. Unlike classical Siglec binding, the interaction is also independent of its sialic acid recognition property. In contrast to WT GBS, mutants lacking β-protein induced efficient pyroptosis of NK cells through the NLRP3 inflammasome, with production and secretion of the proinflammatory cytokine IL-1β and dissemination of the cytotoxic molecule granzyme B. We postulate that GBS evolved β-protein engagement of inhibitory human Siglec-7 to suppress the pyroptotic response of NK cells and thereby block recruitment of a broader innate immune response, i.e., by "silencing the sentinel."
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Affiliation(s)
- Jerry J Fong
- Glycobiology Research and Training Center, School of Medicine, University of California, San Diego, La Jolla, CA 92093
- Department of Cellular and Molecular Medicine, School of Medicine, University of California, San Diego, La Jolla, CA 92093
| | - Chih-Ming Tsai
- Glycobiology Research and Training Center, School of Medicine, University of California, San Diego, La Jolla, CA 92093
- Department of Cellular and Molecular Medicine, School of Medicine, University of California, San Diego, La Jolla, CA 92093
| | - Sudeshna Saha
- Glycobiology Research and Training Center, School of Medicine, University of California, San Diego, La Jolla, CA 92093
- Department of Cellular and Molecular Medicine, School of Medicine, University of California, San Diego, La Jolla, CA 92093
| | - Victor Nizet
- Glycobiology Research and Training Center, School of Medicine, University of California, San Diego, La Jolla, CA 92093
- Department of Pediatrics, School of Medicine, University of California, San Diego, La Jolla, CA 92093
- Skaggs School of Pharmacy and Pharmaceutical Sciences, School of Medicine, University of California, San Diego, La Jolla, CA 92093
| | - Ajit Varki
- Glycobiology Research and Training Center, School of Medicine, University of California, San Diego, La Jolla, CA 92093;
- Department of Cellular and Molecular Medicine, School of Medicine, University of California, San Diego, La Jolla, CA 92093
- Department of Medicine, School of Medicine, University of California, San Diego, La Jolla, CA 92093
| | - Jack D Bui
- Department of Pathology, School of Medicine, University of California, San Diego, La Jolla, CA 92093
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16
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Siddiqui SS, Springer SA, Verhagen A, Sundaramurthy V, Alisson-Silva F, Jiang W, Ghosh P, Varki A. The Alzheimer's disease-protective CD33 splice variant mediates adaptive loss of function via diversion to an intracellular pool. J Biol Chem 2017; 292:15312-15320. [PMID: 28747436 DOI: 10.1074/jbc.m117.799346] [Citation(s) in RCA: 50] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2017] [Revised: 07/20/2017] [Indexed: 12/25/2022] Open
Abstract
The immunomodulatory receptor Siglec-3/CD33 influences risk for late-onset Alzheimer's disease (LOAD), an apparently human-specific post-reproductive disease. CD33 generates two splice variants: a full-length CD33M transcript produced primarily by the "LOAD-risk" allele and a shorter CD33m isoform lacking the sialic acid-binding domain produced primarily from the "LOAD-protective" allele. An SNP that modulates CD33 splicing to favor CD33m is associated with enhanced microglial activity. Individuals expressing more protective isoform accumulate less brain β-amyloid and have a lower LOAD risk. How the CD33m isoform increases β-amyloid clearance remains unknown. We report that the protection by the CD33m isoform may not be conferred by what it does but, rather, from what it cannot do. Analysis of blood neutrophils and monocytes and a microglial cell line revealed that unlike CD33M, the CD33m isoform does not localize to cell surfaces; instead, it accumulates in peroxisomes. Cell stimulation and activation did not mobilize CD33m to the surface. Thus, the CD33m isoform may neither interact directly with amyloid plaques nor engage in cell-surface signaling. Rather, production and localization of CD33m in peroxisomes is a way of diminishing the amount of CD33M and enhancing β-amyloid clearance. We confirmed intracellular localization by generating a CD33m-specific monoclonal antibody. Of note, CD33 is the only Siglec with a peroxisome-targeting sequence, and this motif emerged by convergent evolution in toothed whales, the only other mammals with a prolonged post-reproductive lifespan. The CD33 allele that protects post-reproductive individuals from LOAD may have evolved by adaptive loss-of-function, an example of the less-is-more hypothesis.
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Affiliation(s)
- Shoib S Siddiqui
- From the Center for Academic Research and Training in Anthropogeny (CARTA) and Glycobiology Research and Training Center (GRTC) and.,Departments of Medicine and Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California 92093 and
| | - Stevan A Springer
- From the Center for Academic Research and Training in Anthropogeny (CARTA) and Glycobiology Research and Training Center (GRTC) and.,Departments of Medicine and Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California 92093 and
| | - Andrea Verhagen
- From the Center for Academic Research and Training in Anthropogeny (CARTA) and Glycobiology Research and Training Center (GRTC) and.,Departments of Medicine and Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California 92093 and
| | - Venkatasubramaniam Sundaramurthy
- From the Center for Academic Research and Training in Anthropogeny (CARTA) and Glycobiology Research and Training Center (GRTC) and
| | - Frederico Alisson-Silva
- From the Center for Academic Research and Training in Anthropogeny (CARTA) and Glycobiology Research and Training Center (GRTC) and.,Departments of Medicine and Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California 92093 and
| | | | - Pradipta Ghosh
- Departments of Medicine and Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California 92093 and
| | - Ajit Varki
- From the Center for Academic Research and Training in Anthropogeny (CARTA) and Glycobiology Research and Training Center (GRTC) and .,Departments of Medicine and Cellular and Molecular Medicine, University of California, San Diego, La Jolla, California 92093 and
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17
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Varki A. Are humans prone to autoimmunity? Implications from evolutionary changes in hominin sialic acid biology. J Autoimmun 2017; 83:134-142. [PMID: 28755952 DOI: 10.1016/j.jaut.2017.07.011] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2017] [Revised: 07/13/2017] [Accepted: 07/17/2017] [Indexed: 02/06/2023]
Abstract
Given varied intrinsic and extrinsic challenges to the immune system, it is unsurprising that each evolutionary lineage evolves distinctive features of immunoreactivity, and that tolerance mechanisms fail, allowing autoimmunity. Humans appear prone to many autoimmune diseases, with mechanisms both genetic and environmental. Another rapidly evolving biological system involves sialic acids, a family of monosaccharides that are terminal caps on cell surface and secreted molecules of vertebrates, and play multifarious roles in immunity. We have explored multiple genomic changes in sialic acid biology that occurred in human ancestors (hominins), some with implications for enhanced immunoreactivity, and hence for autoimmunity. Human ancestors lost the enzyme synthesizing the common mammalian sialic acid Neu5Gc, with an accumulation of the precursor sialic acid Neu5Ac. Resulting changes include an enhanced reactivity by some immune cells and increased ability of macrophages to kill bacteria, at the cost of increased endotoxin sensitivity. There are also multiple human-specific evolutionary changes in inhibitory and activating Siglecs, immune cell receptors that recognize sialic acids as "self-associated molecular patterns" (SAMPs) to modulate immunity, but can also be hijacked by pathogen molecular mimicry of SAMPs. Altered expression patterns and fixed or polymorphic SIGLEC pseudogenization in humans has modulated both innate and adaptive immunity, sometimes favoring over-reactivity. Meanwhile, dietary intake of Neu5Gc (derived primarily from red meats) allows metabolic incorporation of this non-human molecule into human cells--apparently the first example of "xeno-autoimmunity" involving "xeno-autoantigen" interactions with circulating "xeno-autoantibodies". Taken together, some of these factors may contribute to the apparent human propensity for autoimmunity.
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Affiliation(s)
- Ajit Varki
- Departments of Medicine and Cellular and Molecular Medicine, Glycobiology Research and Training Center (GRTC) and Center for Academic Research and Training in Anthropogeny (CARTA), University of California, San Diego, La Jolla, CA, 92093-0687, USA.
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18
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Okerblom J, Varki A. Biochemical, Cellular, Physiological, and Pathological Consequences of Human Loss of N-Glycolylneuraminic Acid. Chembiochem 2017; 18:1155-1171. [PMID: 28423240 DOI: 10.1002/cbic.201700077] [Citation(s) in RCA: 52] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/16/2017] [Indexed: 12/15/2022]
Abstract
About 2-3 million years ago, Alu-mediated deletion of a critical exon in the CMAH gene became fixed in the hominin lineage ancestral to humans, possibly through a stepwise process of selection by pathogen targeting of the CMAH product (the sialic acid Neu5Gc), followed by reproductive isolation through female anti-Neu5Gc antibodies. Loss of CMAH has occurred independently in some other lineages, but is functionally intact in Old World primates, including our closest relatives, the chimpanzee. Although the biophysical and biochemical ramifications of losing tens of millions of Neu5Gc hydroxy groups at most cell surfaces remains poorly understood, we do know that there are multiscale effects functionally relevant to both sides of the host-pathogen interface. Hominin CMAH loss might also contribute to understanding human evolution, at the time when our ancestors were starting to use stone tools, increasing their consumption of meat, and possibly hunting. Comparisons with chimpanzees within ethical and practical limitations have revealed some consequences of human CMAH loss, but more has been learned by using a mouse model with a human-like Cmah inactivation. For example, such mice can develop antibodies against Neu5Gc that could affect inflammatory processes like cancer progression in the face of Neu5Gc metabolic incorporation from red meats, display a hyper-reactive immune system, a human-like tendency for delayed wound healing, late-onset hearing loss, insulin resistance, susceptibility to muscular dystrophy pathologies, and increased sensitivity to multiple human-adapted pathogens involving sialic acids. Further studies in such mice could provide a model for other human-specific processes and pathologies involving sialic acid biology that have yet to be explored.
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Affiliation(s)
- Jonathan Okerblom
- Biomedical Sciences Graduate Program, University of California in San Diego, 9500 Gilman Drive, La Jolla, CA, 92093-0687, USA
| | - Ajit Varki
- Glycobiology Research and Training Center, GRTC) and, Center for Academic Research and Training in Anthropogeny, CARTA), Departments of Medicine and Cellular and Molecular Medicine, University of California in San Diego, La Jolla, CA, 92093-0687, USA
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19
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Siglec-7 restores β-cell function and survival and reduces inflammation in pancreatic islets from patients with diabetes. Sci Rep 2017; 7:45319. [PMID: 28378743 PMCID: PMC5381285 DOI: 10.1038/srep45319] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2016] [Accepted: 02/22/2017] [Indexed: 01/16/2023] Open
Abstract
Chronic inflammation plays a key role in both type 1 and type 2 diabetes. Cytokine and chemokine production within the islets in a diabetic milieu results in β-cell failure and diabetes progression. Identification of targets, which both prevent macrophage activation and infiltration into islets and restore β-cell functionality is essential for effective diabetes therapy. We report that certain Sialic-acid-binding immunoglobulin-like-lectins (siglecs) are expressed in human pancreatic islets in a cell-type specific manner. Siglec-7 was expressed on β-cells and down-regulated in type 1 and type 2 diabetes and in infiltrating activated immune cells. Over-expression of Siglec-7 in diabetic islets reduced cytokines, prevented β-cell dysfunction and apoptosis and reduced recruiting of migrating monocytes. Our data suggest that restoration of human Siglec-7 expression may be a novel therapeutic strategy targeted to both inhibition of immune activation and preservation of β-cell function and survival.
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20
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López-Uribe MM, Sconiers WB, Frank SD, Dunn RR, Tarpy DR. Reduced cellular immune response in social insect lineages. Biol Lett 2016; 12:20150984. [PMID: 26961895 DOI: 10.1098/rsbl.2015.0984] [Citation(s) in RCA: 37] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Social living poses challenges for individual fitness because of the increased risk of disease transmission among conspecifics. Despite this challenge, sociality is an evolutionarily successful lifestyle, occurring in the most abundant and diverse group of organisms on earth--the social insects. Two contrasting hypotheses predict the evolutionary consequences of sociality on immune systems. The social group hypothesis posits that sociality leads to stronger individual immune systems because of the higher risk of disease transmission in social species. By contrast, the relaxed selection hypothesis proposes that social species have evolved behavioural immune defences that lower disease risk within the group, resulting in lower immunity at the individual level. We tested these hypotheses by measuring the encapsulation response in 11 eusocial and non-eusocial insect lineages. We built phylogenetic mixed linear models to investigate the effect of behaviour, colony size and body size on cellular immune response. We found a significantly negative effect of colony size on encapsulation response (Markov chain Monte Carlo generalized linear mixed model (mcmcGLMM) p < 0.05; phylogenetic generalized least squares (PGLS) p < 0.05). Our findings suggest that insects living in large societies may rely more on behavioural mechanisms, such as hygienic behaviours, than on immune function to reduce the risk of disease transmission among nest-mates.
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Affiliation(s)
- Margarita M López-Uribe
- Department of Entomology, North Carolina State University Department of Applied Ecology, North Carolina State University W. M. Keck Center for Behavioral Biology, Natural History Museum of Denmark
| | | | - Steven D Frank
- Department of Entomology, North Carolina State University
| | - Robert R Dunn
- Department of Applied Ecology, North Carolina State University W. M. Keck Center for Behavioral Biology, Natural History Museum of Denmark Center for Macroecology and Evolution and Climate, Natural History Museum of Denmark
| | - David R Tarpy
- Department of Entomology, North Carolina State University W. M. Keck Center for Behavioral Biology, Natural History Museum of Denmark
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21
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Siddiqui S, Schwarz F, Springer S, Khedri Z, Yu H, Deng L, Verhagen A, Naito-Matsui Y, Jiang W, Kim D, Zhou J, Ding B, Chen X, Varki N, Varki A. Studies on the Detection, Expression, Glycosylation, Dimerization, and Ligand Binding Properties of Mouse Siglec-E. J Biol Chem 2016; 292:1029-1037. [PMID: 27920204 DOI: 10.1074/jbc.m116.738351] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2016] [Revised: 12/02/2016] [Indexed: 12/20/2022] Open
Abstract
CD33-related Siglecs are a family of proteins widely expressed on innate immune cells. Binding of sialylated glycans or other ligands triggers signals that inhibit or activate inflammation. Immunomodulation by Siglecs has been extensively studied, but relationships between structure and functions are poorly explored. Here we present new data relating to the structure and function of Siglec-E, the major CD33-related Siglec expressed on mouse neutrophils, monocytes, macrophages, and dendritic cells. We generated nine new rat monoclonal antibodies specific to mouse Siglec-E, with no cross-reactivity to Siglec-F. Although all antibodies detected Siglec-E on transfected human HEK-293T cells, only two reacted with mouse bone marrow neutrophils by flow cytometry and on spleen sections by immunohistochemistry. Moreover, whereas all antibodies recognized Siglec-E-Fc on immunoblots, binding was dependent on intact disulfide bonds and N-glycans, and only two antibodies recognized native Siglec-E within spleen lysates. Thus, we further investigated the impact of Siglec-E homodimerization. Homology-based structural modeling predicted a cysteine residue (Cys-298) in position to form a disulfide bridge between two Siglec-E polypeptides. Mutagenesis of Cys-298 confirmed its role in dimerization. In keeping with the high level of 9-O-acetylation found in mice, sialoglycan array studies indicate that this modification has complex effects on recognition by Siglec-E, in relationship to the underlying structures. However, we found no differences in phosphorylation or SHP-1 recruitment between dimeric and monomeric Siglec-E expressed on HEK293A cells. Phylogenomic analyses predicted that only some human and mouse Siglecs form disulfide-linked dimers. Notably, Siglec-9, the functionally equivalent human paralog of Siglec-E, occurs as a monomer.
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Affiliation(s)
- Shoib Siddiqui
- From the Departments of Medicine and Cellular & Molecular Medicine, Glycobiology Research and Training Center (GRTC), University of California San Diego, La Jolla, California 92093-0687
| | - Flavio Schwarz
- From the Departments of Medicine and Cellular & Molecular Medicine, Glycobiology Research and Training Center (GRTC), University of California San Diego, La Jolla, California 92093-0687
| | - Stevan Springer
- From the Departments of Medicine and Cellular & Molecular Medicine, Glycobiology Research and Training Center (GRTC), University of California San Diego, La Jolla, California 92093-0687
| | - Zahra Khedri
- From the Departments of Medicine and Cellular & Molecular Medicine, Glycobiology Research and Training Center (GRTC), University of California San Diego, La Jolla, California 92093-0687
| | - Hai Yu
- the Department of Chemistry, University of California, Davis, California 95616, and
| | - Lingquan Deng
- From the Departments of Medicine and Cellular & Molecular Medicine, Glycobiology Research and Training Center (GRTC), University of California San Diego, La Jolla, California 92093-0687
| | - Andrea Verhagen
- From the Departments of Medicine and Cellular & Molecular Medicine, Glycobiology Research and Training Center (GRTC), University of California San Diego, La Jolla, California 92093-0687
| | - Yuko Naito-Matsui
- From the Departments of Medicine and Cellular & Molecular Medicine, Glycobiology Research and Training Center (GRTC), University of California San Diego, La Jolla, California 92093-0687
| | | | - Daniel Kim
- BioLegend, Inc., San Diego, California 92121
| | - Jie Zhou
- BioLegend, Inc., San Diego, California 92121
| | - Beibei Ding
- BioLegend, Inc., San Diego, California 92121
| | - Xi Chen
- the Department of Chemistry, University of California, Davis, California 95616, and
| | - Nissi Varki
- From the Departments of Medicine and Cellular & Molecular Medicine, Glycobiology Research and Training Center (GRTC), University of California San Diego, La Jolla, California 92093-0687
| | - Ajit Varki
- From the Departments of Medicine and Cellular & Molecular Medicine, Glycobiology Research and Training Center (GRTC), University of California San Diego, La Jolla, California 92093-0687,
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22
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Abstract
An important underlying mechanism that contributes to autoimmunity is the loss of inhibitory signaling in the immune system. Sialic acid-recognizing Ig superfamily lectins or Siglecs are a family of cell surface proteins largely expressed in hematopoietic cells. The majority of Siglecs are inhibitory receptors expressed in immune cells that bind to sialic acid-containing ligands and recruit SH2-domain-containing tyrosine phosphatases to their cytoplasmic tails. They deliver inhibitory signals that can contribute to the constraining of immune cells, and thus protect the host from autoimmunity. The inhibitory functions of CD22/Siglec-2 and Siglec-G and their contributions to tolerance and autoimmunity, primarily in the B lymphocyte context, are considered in some detail in this review. The relevance to autoimmunity and unregulated inflammation of modified sialic acids, enzymes that modify sialic acid, and other sialic acid-binding proteins are also reviewed.
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Affiliation(s)
- Vinay S Mahajan
- Ragon Institute of MGH, MIT and Harvard, Cambridge, MA, USA.,Departments of Medicine and Pathology, Harvard Medical School, Boston, MA, USA.,Deaprtment of Pathology, Brigham and Women's Hospital, Boston, MA, USA
| | - Shiv Pillai
- Ragon Institute of MGH, MIT and Harvard, Cambridge, MA, USA.,Departments of Medicine and Pathology, Harvard Medical School, Boston, MA, USA
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23
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Schofield CL, Marín MJ, Rejzek M, Crocker PR, Field RA, Russell DA. Detection of mSiglec-E, in solution and expressed on the surface of Chinese hamster ovary cells, using sialic acid functionalised gold nanoparticles. Analyst 2016; 141:5799-5809. [PMID: 27537280 DOI: 10.1039/c6an01230b] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023]
Abstract
Sialic acids are widespread in biology, fulfilling a wide range of functions. Their cognate lectin receptors - Siglecs - are equally diverse and widely distributed, with different Siglecs found within distinct populations of cells in the haemopoietic, immune and nervous systems. A convenient way to assay ligand recognition of soluble Siglecs would be useful, as would methods for the concomitant assessment of Siglec distribution on cell surfaces. Here we report the use of gold nanoparticles functionalised with a sialic acid ligand diluted with a polyethylene glycol (PEG) ligand for the plasmonic detection of a soluble form of murine Siglec-E (mSiglec-E-Fc fusion protein) and, importantly, for the specific detection of the same Siglec expressed on the surface of mammalian cells. These sialic acid functionalised nanoparticles are shown to overcome problems such as cellular cis interactions and low Siglec-ligand affinity. The gold nanoparticles were functionalised with various ratios of sialic acid : PEG ligands and the optimum ratio for the detection of murine Siglec-E was established based on the plasmonic detection of the soluble pre-complexed recombinant form of murine Siglec-E (mSiglec-E-Fc fusion protein). The optimum ratio for the detection of the fusion protein was found to be sialic acid : PEG ligands in a 50 : 50 ratio (glyconanoparticles 1). The optimised glyconanoparticles 1 were used to recognise and bind to the murine Siglec-E expressed on the surface of transfected Chinese hamster ovary cells as determined by transmission electron microscopy.
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Affiliation(s)
- Claire L Schofield
- School of Chemistry, University of East Anglia, Norwich Research Park, Norwich, NR4 7TJ, UK.
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24
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Human-specific derived alleles of CD33 and other genes protect against postreproductive cognitive decline. Proc Natl Acad Sci U S A 2015; 113:74-9. [PMID: 26621708 DOI: 10.1073/pnas.1517951112] [Citation(s) in RCA: 58] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The individuals of most vertebrate species die when they can no longer reproduce. Humans are a rare exception, having evolved a prolonged postreproductive lifespan. Elders contribute to cooperative offspring care, assist in foraging, and communicate important ecological and cultural knowledge, increasing the survival of younger individuals. Age-related deterioration of cognitive capacity in humans compromises these benefits and also burdens the group with socially costly members. We investigated the contribution of the immunoregulatory receptor CD33 to a uniquely human postreproductive disease, Alzheimer's dementia. Surprisingly, even though selection at advanced age is expected to be weak, a CD33 allele protective against Alzheimer's disease is derived and unique to humans and favors a functional molecular state of CD33 resembling that of the chimpanzee. Thus, derived alleles may be compensatory and restore interactions altered as a consequence of human-specific brain evolution. We found several other examples of derived alleles at other human loci that protect against age-related cognitive deterioration arising from neurodegenerative disease or cerebrovascular insufficiency. Selection by inclusive fitness may be strong enough to favor alleles protecting specifically against cognitive decline in postreproductive humans. Such selection would operate by maximizing the contributions of postreproductive individuals to the fitness of younger kin.
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25
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Springer SA, Gagneux P. Glycomics: revealing the dynamic ecology and evolution of sugar molecules. J Proteomics 2015; 135:90-100. [PMID: 26626628 DOI: 10.1016/j.jprot.2015.11.022] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/05/2015] [Revised: 11/11/2015] [Accepted: 11/23/2015] [Indexed: 01/11/2023]
Abstract
Sugars are the most functionally and structurally diverse molecules in the biological world. Glycan structures range from tiny single monosaccharide units to giant chains thousands of units long. Some glycans are branched, their monosaccharides linked together in many different combinations and orientations. Some exist as solitary molecules; others are conjugated to proteins and lipids and alter their collective functional properties. In addition to structural and storage roles, glycan molecules participate in and actively regulate physiological and developmental processes. Glycans also mediate cellular interactions within and between individuals. Their roles in ecology and evolution are pivotal, but not well studied because glycan biochemistry requires different methods than standard molecular biology practice. The properties of glycans are in some ways convenient, and in others challenging. Glycans vary on organismal timescales, and in direct response to physiological and ecological conditions. Their mature structures are physical records of both genetic and environmental influences during maturation. We describe the scope of natural glycan variation and discuss how studying glycans will allow researchers to further integrate the fields of ecology and evolution.
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Affiliation(s)
- Stevan A Springer
- Glycobiology Research and Training Center, University of California San Diego, La Jolla, CA 92039, USA; Cellular and Molecular Medicine, University of California San Diego, La Jolla, CA 92039, USA.
| | - Pascal Gagneux
- Glycobiology Research and Training Center, University of California San Diego, La Jolla, CA 92039, USA; Department of Pathology, University of California San Diego, La Jolla, CA 92039, USA.
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26
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Pearce OMT, Läubli H. Sialic acids in cancer biology and immunity. Glycobiology 2015; 26:111-28. [DOI: 10.1093/glycob/cwv097] [Citation(s) in RCA: 259] [Impact Index Per Article: 28.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2015] [Accepted: 10/26/2015] [Indexed: 02/07/2023] Open
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27
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Fong JJ, Sreedhara K, Deng L, Varki NM, Angata T, Liu Q, Nizet V, Varki A. Immunomodulatory activity of extracellular Hsp70 mediated via paired receptors Siglec-5 and Siglec-14. EMBO J 2015; 34:2775-88. [PMID: 26459514 DOI: 10.15252/embj.201591407] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2015] [Accepted: 09/18/2015] [Indexed: 12/16/2022] Open
Abstract
The intracellular chaperone heat-shock protein 70 (Hsp70) can be secreted from cells, but its extracellular role is unclear, as the protein has been reported to both activate and suppress the innate immune response. Potential immunomodulatory receptors on myelomonocytic lineage cells that bind extracellular Hsp70 are not well defined. Siglecs are Ig-superfamily lectins on mammalian leukocytes that recognize sialic acid-bearing glycans and thereby modulate immune responses. Siglec-5 and Siglec-14, expressed on monocytes and neutrophils, share identical ligand-binding domains but have opposing signaling functions. Based on phylogenetic analyses of these receptors, we predicted that endogenous sialic acid-independent ligands should exist. An unbiased screen revealed Hsp70 as a ligand for Siglec-5 and Siglec-14. Hsp70 stimulation through Siglec-5 delivers an anti-inflammatory signal, while stimulation through Siglec-14 is pro-inflammatory. The functional consequences of this interaction are also addressed in relation to a SIGLEC14 polymorphism found in humans. Our results demonstrate that an endogenous non-sialic acid-bearing molecule can be either a danger-associated or self-associated signal through paired Siglecs, and may explain seemingly contradictory prior reports on extracellular Hsp70 action.
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Affiliation(s)
- Jerry J Fong
- Glycobiology Research and Training Center, Skaggs School of Pharmacy and Pharmaceutical Sciences, La Jolla, CA, USA Department of Cellular and Molecular Medicine, Skaggs School of Pharmacy and Pharmaceutical Sciences, La Jolla, CA, USA
| | - Karthik Sreedhara
- Glycobiology Research and Training Center, Skaggs School of Pharmacy and Pharmaceutical Sciences, La Jolla, CA, USA Department of Cellular and Molecular Medicine, Skaggs School of Pharmacy and Pharmaceutical Sciences, La Jolla, CA, USA
| | - Liwen Deng
- Glycobiology Research and Training Center, Skaggs School of Pharmacy and Pharmaceutical Sciences, La Jolla, CA, USA Department of Pathology, Skaggs School of Pharmacy and Pharmaceutical Sciences, La Jolla, CA, USA
| | - Nissi M Varki
- Glycobiology Research and Training Center, Skaggs School of Pharmacy and Pharmaceutical Sciences, La Jolla, CA, USA Department of Pathology, Skaggs School of Pharmacy and Pharmaceutical Sciences, La Jolla, CA, USA Department of Medicine, Skaggs School of Pharmacy and Pharmaceutical Sciences, La Jolla, CA, USA
| | - Takashi Angata
- Institute of Biological Chemistry, Academia Sinica, Taipei, Taiwan
| | - Qinglian Liu
- Department of Physiology and Biophysics, School of Medicine, Virginia Commonwealth University, Richmond, VA, USA
| | - Victor Nizet
- Glycobiology Research and Training Center, Skaggs School of Pharmacy and Pharmaceutical Sciences, La Jolla, CA, USA Department of Pediatrics, Skaggs School of Pharmacy and Pharmaceutical Sciences, La Jolla, CA, USA UC San Diego School of Medicine, Skaggs School of Pharmacy and Pharmaceutical Sciences, La Jolla, CA, USA Skaggs School of Pharmacy and Pharmaceutical Sciences, La Jolla, CA, USA
| | - Ajit Varki
- Glycobiology Research and Training Center, Skaggs School of Pharmacy and Pharmaceutical Sciences, La Jolla, CA, USA Department of Cellular and Molecular Medicine, Skaggs School of Pharmacy and Pharmaceutical Sciences, La Jolla, CA, USA Department of Medicine, Skaggs School of Pharmacy and Pharmaceutical Sciences, La Jolla, CA, USA UC San Diego School of Medicine, Skaggs School of Pharmacy and Pharmaceutical Sciences, La Jolla, CA, USA
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Malik M, Parikh I, Vasquez JB, Smith C, Tai L, Bu G, LaDu MJ, Fardo DW, Rebeck GW, Estus S. Genetics ignite focus on microglial inflammation in Alzheimer's disease. Mol Neurodegener 2015; 10:52. [PMID: 26438529 PMCID: PMC4595327 DOI: 10.1186/s13024-015-0048-1] [Citation(s) in RCA: 99] [Impact Index Per Article: 11.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2015] [Accepted: 09/23/2015] [Indexed: 12/12/2022] Open
Abstract
In the past five years, a series of large-scale genetic studies have revealed novel risk factors for Alzheimer’s disease (AD). Analyses of these risk factors have focused attention upon the role of immune processes in AD, specifically microglial function. In this review, we discuss interpretation of genetic studies. We then focus upon six genes implicated by AD genetics that impact microglial function: TREM2, CD33, CR1, ABCA7, SHIP1, and APOE. We review the literature regarding the biological functions of these six proteins and their putative role in AD pathogenesis. We then present a model for how these factors may interact to modulate microglial function in AD.
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Affiliation(s)
- Manasi Malik
- Department of Physiology and Sanders-Brown Center on Aging, University of Kentucky, 800 S. Limestone St, Lexington, KY, 40536, USA.
| | - Ishita Parikh
- Department of Physiology and Sanders-Brown Center on Aging, University of Kentucky, 800 S. Limestone St, Lexington, KY, 40536, USA.
| | - Jared B Vasquez
- Department of Physiology and Sanders-Brown Center on Aging, University of Kentucky, 800 S. Limestone St, Lexington, KY, 40536, USA.
| | - Conor Smith
- Department of Anatomy and Cell Biology, University of Illinois, Chicago, IL, USA.
| | - Leon Tai
- Department of Anatomy and Cell Biology, University of Illinois, Chicago, IL, USA.
| | - Guojun Bu
- Department of Neuroscience, Mayo Clinic, Jacksonville, FL, USA.
| | - Mary Jo LaDu
- Department of Anatomy and Cell Biology, University of Illinois, Chicago, IL, USA.
| | - David W Fardo
- Department of Biostatistics and Sanders-Brown Center on Aging, University of Kentucky, Lexington, KY, USA.
| | - G William Rebeck
- Department of Neuroscience, Georgetown University Medical Center, Washington, DC, USA.
| | - Steven Estus
- Department of Physiology and Sanders-Brown Center on Aging, University of Kentucky, 800 S. Limestone St, Lexington, KY, 40536, USA.
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Schwarz F, Pearce OMT, Wang X, Samraj AN, Läubli H, Garcia JO, Lin H, Fu X, Garcia-Bingman A, Secrest P, Romanoski CE, Heyser C, Glass CK, Hazen SL, Varki N, Varki A, Gagneux P. Siglec receptors impact mammalian lifespan by modulating oxidative stress. eLife 2015; 4. [PMID: 25846707 PMCID: PMC4384638 DOI: 10.7554/elife.06184] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2014] [Accepted: 03/08/2015] [Indexed: 12/12/2022] Open
Abstract
Aging is a multifactorial process that includes the lifelong accumulation of molecular damage, leading to age-related frailty, disability and disease, and eventually death. In this study, we report evidence of a significant correlation between the number of genes encoding the immunomodulatory CD33-related sialic acid-binding immunoglobulin-like receptors (CD33rSiglecs) and maximum lifespan in mammals. In keeping with this, we show that mice lacking Siglec-E, the main member of the CD33rSiglec family, exhibit reduced survival. Removal of Siglec-E causes the development of exaggerated signs of aging at the molecular, structural, and cognitive level. We found that accelerated aging was related both to an unbalanced ROS metabolism, and to a secondary impairment in detoxification of reactive molecules, ultimately leading to increased damage to cellular DNA, proteins, and lipids. Taken together, our data suggest that CD33rSiglecs co-evolved in mammals to achieve a better management of oxidative stress during inflammation, which in turn reduces molecular damage and extends lifespan. DOI:http://dx.doi.org/10.7554/eLife.06184.001 As we get older, we are more likely to become frail, be less mobile and develop heart disease, diabetes, and other age-related diseases. This is partly due to damage to tissues and organs that accumulates over the course of our lifetime. How quickly we age is controlled both by our genetics and by the environment we live in. It is thought that damage to DNA, proteins, and other molecules in the body caused by chemically active molecules called reactive oxygen species (ROS) can influence aging. ROS are produced during respiration, immune responses, and other important processes in cells, but in excessive amounts they can be extremely harmful. To avoid damage to DNA and other important molecules, cells have several ways to control the levels of ROS. One of the other hallmarks of aging is the development of chronic inflammation in tissues around the body, which is partly triggered by the immune system in response to cell damage. A group of genes called the CD33rSIGLEC genes are involved in controlling inflammation. The genomes of different mammal species carry different numbers of these genes, but it is not clear whether this alters the aging process in these animals. In this study, Schwarz et al. investigated whether the CD33rSIGLEC genes influence the lifespans of mammals. Species with a higher number of CD33rSIGLEC genes generally have a longer lifespan than those with fewer of these genes. Mice that were missing one of these genes and were subjected to inflammation early in life showed signs of accelerated aging and had shortened lifespans compared with normal mice. As predicted, these mice also had higher levels of ROS, which led to a greater amount of damage to the DNA and other molecules in their bodies. Schwarz et al.'s findings suggest that the CD33rSIGLECs co-evolved in mammals to help control the levels of ROS during inflammation, thereby reducing the damage to cells and extending the lifespan of the animals. Given that individual humans have different numbers of working CD33rSIGLEC genes, it would be interesting to see if this influences human lifespan. DOI:http://dx.doi.org/10.7554/eLife.06184.002
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Affiliation(s)
- Flavio Schwarz
- Glycobiology Research and Training Center, University of California, San Diego, San Diego, United States
| | - Oliver M T Pearce
- Glycobiology Research and Training Center, University of California, San Diego, San Diego, United States
| | - Xiaoxia Wang
- Glycobiology Research and Training Center, University of California, San Diego, San Diego, United States
| | - Annie N Samraj
- Glycobiology Research and Training Center, University of California, San Diego, San Diego, United States
| | - Heinz Läubli
- Glycobiology Research and Training Center, University of California, San Diego, San Diego, United States
| | - Javier O Garcia
- Department of Psychology, University of California, San Diego, San Diego, United States
| | - Hongqiao Lin
- Department of Cellular and Molecular Medicine, Cleveland Clinic Lerner Research Institute, Cleveland, United States
| | - Xiaoming Fu
- Department of Cellular and Molecular Medicine, Cleveland Clinic Lerner Research Institute, Cleveland, United States
| | - Andrea Garcia-Bingman
- Glycobiology Research and Training Center, University of California, San Diego, San Diego, United States
| | - Patrick Secrest
- Glycobiology Research and Training Center, University of California, San Diego, San Diego, United States
| | - Casey E Romanoski
- Department of Cellular and Molecular Medicine, University of California, San Diego, San Diego, United States
| | - Charles Heyser
- Department of Neurosciences, University of California, San Diego, San Diego, United States
| | - Christopher K Glass
- Department of Cellular and Molecular Medicine, University of California, San Diego, San Diego, United States
| | - Stanley L Hazen
- Department of Cellular and Molecular Medicine, Cleveland Clinic Lerner Research Institute, Cleveland, United States
| | - Nissi Varki
- Glycobiology Research and Training Center, University of California, San Diego, San Diego, United States
| | - Ajit Varki
- Glycobiology Research and Training Center, University of California, San Diego, San Diego, United States
| | - Pascal Gagneux
- Glycobiology Research and Training Center, University of California, San Diego, San Diego, United States
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