1
|
Schnaar RL. Gangliosides as Siglec ligands. Glycoconj J 2023; 40:159-167. [PMID: 36701102 PMCID: PMC11000168 DOI: 10.1007/s10719-023-10101-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Revised: 01/09/2023] [Accepted: 01/13/2023] [Indexed: 01/27/2023]
Abstract
The structure of a sialoglycan can be translated into to a biological response when it binds to a specific endogenous lectin. Among endogenous sialic acid-binding lectins in humans are those comprising the 15-member Siglec family, most of which are expressed on overlapping sets of immune cells. Endogenous Siglec ligands are sialoglycolipids (gangliosides) and/or sialoglycoproteins, on cell surfaces or in the extracellular milieu, that bind to and initiate signaling by cell surface Siglecs. In the nervous system, where gangliosides are the predominant sialoglycans, Siglec-4 (myelin-associated glycoprotein) on myelinating cells binds to gangliosides GD1a and GT1b on nerve cell axons to ensure stable and productive axon-myelin interactions. In the immune system, Siglec-7 on natural killer cells binds to gangliosides GD3 and GD2 to inhibit immune signaling. Expression of GD3 and GD2 on cancer cells can lead to tumor immune evasion. Siglec-1 (sialoadhesin, CD169) on macrophages binds to gangliosides on tumors and enveloped viruses. This may enhance antigen presentation in some cases, or increase viral distribution in others. Several other Siglecs bind to gangliosides in vitro, the biological significance of which has yet to be fully established. Gangliosides, which are found on all human cells and tissues in cell-specific distributions, are functional Siglec ligands with varied roles driving Siglec-mediated signaling.
Collapse
Affiliation(s)
- Ronald L Schnaar
- Department of Pharmacology and Molecular Sciences, Department of Neuroscience, Johns Hopkins University School of Medicine, 725 N Wolfe St, Baltimore, MD, 21205, USA.
| |
Collapse
|
2
|
Kiefer A, Plattner E, Ruppel R, Weiss C, Zhou-Suckow Z, Mall M, Renner M, Müller H. DMBT1 is upregulated in cystic fibrosis, affects ciliary motility, and is reduced by acetylcysteine. Mol Cell Pediatr 2022; 9:4. [PMID: 35249163 PMCID: PMC8898207 DOI: 10.1186/s40348-022-00136-0] [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: 08/29/2021] [Accepted: 01/26/2022] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Cystic fibrosis (CF) is the most common genetic disorder in the Caucasian population. Despite remarkable improvements in morbidity and mortality during the last decades, the disease still limits survival and reduces quality of life of affected patients. Moreover, CF still represents substantial economic burden for healthcare systems. Inflammation and infection already start in early life and play important roles in pulmonary impairment. The aim of this study is to analyze the potential role of DMBT1, a protein with functions in inflammation, angiogenesis, and epithelial differentiation, in CF. RESULTS Immunohistochemically DMBT1 protein expression was upregulated in lung tissues of CF patients compared to healthy controls. Additionally, pulmonary expression of Dmbt1 was approximately 6-fold increased in an established transgenic mouse model of CF-like lung disease (ENaC tg) compared to wild-type mice as detected by qRT-PCR. Since acetylcysteine (ACC) has been shown to reduce inflammatory markers in the airways, its potential influence on DMBT1 expression was analyzed. A549 cells stably transfected with an expression plasmid encoding the largest (8kb) DMBT1 variant (DMBT1+ cells) or an empty vector control (DMBT1- cells) and incubated with ACC both showed significantly reduced DMBT1 concentrations in the culture medium (p = 0.0001). To further elucidate the function of DMBT1 in pulmonary airways, respiratory epithelial cells were examined by phase contrast microscopy. Addition of human recombinant DMBT1 resulted in altered cilia motility and irregular beat waves (p < 0.0001) suggesting a potential effect of DMBT1 on airway clearance. CONCLUSIONS DMBT1 is part of inflammatory processes in CF and may be used as a potential biomarker for CF lung disease and a potential tool to monitor CF progression. Furthermore, DMBT1 has a negative effect on ciliary motility thereby possibly compromising airway clearance. Application of ACC, leading to reduced DMBT1 concentrations, could be a potential therapeutic option for CF patients.
Collapse
Affiliation(s)
- Alexander Kiefer
- Department of Pediatrics, University Hospital Erlangen, University of Erlangen-Nürnberg, Loschgestr. 15, 91054, Erlangen, Germany.,Department of Pediatric Pneumology and Allergology, St. Hedwig's Hospital of the Order of St. John, University Children's Hospital Regensburg (KUNO), Steinmetzstr. 1-3, 93049, Regensburg, Germany
| | - Erika Plattner
- Department of Pediatrics, University Hospital Erlangen, University of Erlangen-Nürnberg, Loschgestr. 15, 91054, Erlangen, Germany
| | - Renate Ruppel
- Department of Pediatrics, University Hospital Erlangen, University of Erlangen-Nürnberg, Loschgestr. 15, 91054, Erlangen, Germany
| | - Christel Weiss
- Department of Medical Statistics and Biomathematics, University Hospital Mannheim, Theodor-Kutzer-Ufer 1-3, 68167, Mannheim, Germany
| | - Zhe Zhou-Suckow
- Department of Translational Pulmonology, Translational Lung Research Center Heidelberg (TLRC), German Center for Lung Research (DZL), University of Heidelberg, Im Neuenheimer Feld, 69120, Heidelberg, Germany
| | - Marcus Mall
- Department of Pediatric Pulmonology, Immunology and Critical Care Medicine, Charité-Universitätsmedizin Berlin, Augustenburger Platz 1, 13353, Berlin, Germany
| | - Marcus Renner
- Institute of Pathology, University of Heidelberg, Im Neuenheimer Feld 224, 69120, Heidelberg, Germany
| | - Hanna Müller
- Department of Pediatrics, Neonatology and Pediatric Intensive Care, University of Marburg, Baldingerstraße, 35043, Marburg, Germany. .,Department of Pediatrics, Division of Neonatology and Pediatric Intensive Care, University Hospital Erlangen, University of Erlangen-Nürnberg, Loschgestr. 15, 91054, Erlangen, Germany.
| |
Collapse
|
3
|
Abstract
A dense and diverse array of glycans on glycoproteins and glycolipids decorate all cell surfaces. In vertebrates, many of these carry sialic acid, in a variety of linkages and glycan contexts, as their outermost sugar moiety. Among their functions, glycans engage complementary glycan binding proteins (lectins) to regulate cell physiology. Among the glycan binding proteins are the Siglecs, sialic acid binding immunoglobulin-like lectins. In humans, there are 14 Siglecs, most of which are expressed on overlapping subsets of immune system cells. Each Siglec engages distinct, endogenous sialylated glycans that initiate signaling programs and regulate cellular responses. Here, we explore the emerging science of Siglec ligands, including endogenous sialoglycoproteins and glycolipids and synthetic sialomimetics. Knowledge in this field promises to reveal new molecular pathways controlling cell physiology and new opportunities for therapeutic intervention.
Collapse
|