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Yi S, Feng Y, Wang Y, Ma F. Sialylation: fate decision of mammalian sperm development, fertilization, and male fertility†. Biol Reprod 2023; 109:137-155. [PMID: 37379321 DOI: 10.1093/biolre/ioad067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/03/2023] [Revised: 06/14/2023] [Accepted: 06/19/2023] [Indexed: 06/30/2023] Open
Abstract
Sperm development, maturation, and successful fertilization within the female reproductive tract are intricate and orderly processes that involve protein translation and post-translational modifications. Among these modifications, sialylation plays a crucial role. Any disruptions occurring throughout the sperm's life cycle can result in male infertility, yet our current understanding of this process remains limited. Conventional semen analysis often fails to diagnose some infertility cases associated with sperm sialylation, emphasizing the need to comprehend and investigate the characteristics of sperm sialylation. This review reanalyzes the significance of sialylation in sperm development and fertilization and evaluates the impact of sialylation damage on male fertility under pathological conditions. Sialylation serves a vital role in the life journey of sperm, providing a negatively charged glycocalyx and enriching the molecular structure of the sperm surface, which is beneficial to sperm reversible recognition and immune interaction. These characteristics are particularly crucial during sperm maturation and fertilization within the female reproductive tract. Moreover, enhancing the understanding of the mechanism underlying sperm sialylation can promote the development of relevant clinical indicators for infertility detection and treatment.
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Affiliation(s)
- Shiqi Yi
- Center for Translational Medicine, Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, P.R. China
- Department of Obstetrics and Gynecology, West China Second Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Ying Feng
- West China School of Basic Medical Sciences & Forensic Medicine, Sichuan University, Chengdu, Sichuan, China
| | - Yan Wang
- Department of Obstetrics and Gynecology, West China Second Hospital, Sichuan University, Chengdu, Sichuan, China
| | - Fang Ma
- Center for Translational Medicine, Key Laboratory of Birth Defects and Related Diseases of Women and Children (Sichuan University), Ministry of Education, West China Second University Hospital, Sichuan University, Chengdu, Sichuan, P.R. China
- Department of Obstetrics and Gynecology, West China Second Hospital, Sichuan University, Chengdu, Sichuan, China
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Cohen M. Notable Aspects of Glycan-Protein Interactions. Biomolecules 2015; 5:2056-72. [PMID: 26340640 PMCID: PMC4598788 DOI: 10.3390/biom5032056] [Citation(s) in RCA: 33] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2015] [Revised: 08/27/2015] [Accepted: 08/27/2015] [Indexed: 01/01/2023] Open
Abstract
This mini review highlights several interesting aspects of glycan-mediated interactions that are common between cells, bacteria, and viruses. Glycans are ubiquitously found on all living cells, and in the extracellular milieu of multicellular organisms. They are known to mediate initial binding and recognition events of both immune cells and pathogens with their target cells or tissues. The host target tissues are hidden under a layer of secreted glycosylated decoy targets. In addition, pathogens can utilize and display host glycans to prevent identification as foreign by the host’s immune system (molecular mimicry). Both the host and pathogens continually evolve. The host evolves to prevent infection and the pathogens evolve to evade host defenses. Many pathogens express both glycan-binding proteins and glycosidases. Interestingly, these proteins are often located at the tip of elongated protrusions in bacteria, or in the leading edge of the cell. Glycan-protein interactions have low affinity and, as a result, multivalent interactions are often required to achieve biologically relevant binding. These enable dynamic forms of adhesion mechanisms, reviewed here, and include rolling (cells), stick and roll (bacteria) or surfacing (viruses).
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Affiliation(s)
- Miriam Cohen
- Depatment of Cellular and Molecular Medicine, University of California, San Diego, 9500 Gilman Drive, BRF2 MC 0687, La Jolla, CA 92093-0687, USA.
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Immunodetection of P-selectin using an antibody to its C-terminal tag. Methods Mol Biol 2015; 1312:293-9. [PMID: 26044012 DOI: 10.1007/978-1-4939-2694-7_31] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023]
Abstract
P-selectin is a multi-domain glycoprotein expressed on activated endothelial cells and activated platelets. We previously expressed a recombinant form of P-selectin containing only its N-terminal lectin and EGF domains in CHO-K1 cells and showed that these two domains are sufficient to mediate ligand binding. We have now expressed the same construct in CHO-Lec1 cells that make truncated glycans. The uniform glycosylation in these cells should make it easier to crystallize this protein.
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Regulation of T cell trafficking by the T cell immunoglobulin and mucin domain 1 glycoprotein. Trends Mol Med 2014; 20:675-84. [DOI: 10.1016/j.molmed.2014.10.003] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/19/2014] [Revised: 09/30/2014] [Accepted: 10/13/2014] [Indexed: 12/30/2022]
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Abstract
INTRODUCTION Under conditions of blood flow, selectins mediate the intercellular adhesion between erythrocytes, leukocytes, platelets and vascular endothelium that contribute to vaso-occlusion and tissue damage in sickle cell disease (SCD). Therefore, selectin antagonists have the potential to ameliorate SCD. AREAS COVERED In this review, the author discusses the cellular and molecular basis of vaso-occlusion in SCD, and presents evidence that selectin-mediated cell adhesion has clinical importance in this disorder. The author discusses molecular structure of human selectins and their physiological ligands and highlights clinical trials of selectin-targeted therapy of SCD. Herein, the author also assesses the benefits and limitations of the selectin antagonists that are currently under evaluation for SCD, and offers suggestions for the future. EXPERT OPINION In Phase I and II clinical trials, rivipansel and heparin demonstrated promising efficacy and safety in SCD. Although selectin blockade could potentially impair immune response, an increased incidence of infection was not reported in SCD patients treated with heparin (n = 127) or rivipansel (n = 111). The efficacy and safety findings from Phase I and II clinical studies are encouraging the commencement of Phase III studies to further evaluate selectin-targeted therapy in SCD.
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Affiliation(s)
- Iheanyi Okpala
- University of Nigeria, College of Medicine, Department of Haematology/Immunology , Enugu Campus , Nigeria
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Nakatani K, Yoshimoto S, Asai O, Sakan H, Terada M, Saito Y, Nose M, Iwano M, Konishi N. Enhanced expression of the soluble form of E-selectin attenuates progression of lupus nephritis and vasculitis in MRL/lpr mice. IMMUNITY INFLAMMATION AND DISEASE 2013; 1:37-46. [PMID: 25400916 PMCID: PMC4217541 DOI: 10.1002/iid3.6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 04/07/2013] [Revised: 07/08/2013] [Accepted: 07/30/2013] [Indexed: 01/07/2023]
Abstract
Systemic lupus erythematosus (SLE) is a chronic autoimmune disease that causes inflammatory tissue damage, including lupus nephritis and vasculitis. Local generation of adhesion molecules and expression of their ligands on inflammatory cells appears to contribute to the progression of SLE. We found significantly increased E-selectin expression in the glomeruli and renal interstitial microvasculature of MRL/MpJ-lpr/lpr (MRL/lpr) lupus model mice. This was accompanied with infiltration of inflammatory cells, especially macrophages and CD8(+) T cells. Similarly, in 21 patients with proliferative lupus nephritis, there was a significant correlation between renal E-selectin levels and macrophage and CD8(+) T cell infiltration in the affected kidneys. By contrast, in transgenic MRL/lpr mice exhibiting elevated levels of circulating soluble E-selectin (sE-selectin) protein, which competitively inhibits E- and P-selectin-mediated extravasation of inflammatory cells, the progression of lupus nephritis and vasculitis was significantly suppressed and survival was significantly prolonged. This improvement was accompanied by significant reductions in renal infiltration by macrophages and CD8(+) T cells. These results suggest that E-selectin plays a crucial role in lupus nephritis and vasculitis by mediating renal infiltration of inflammatory cells, and that because it inhibits this process, sE-selectin could potentially serve as an effective treatment for lupus nephritis and vasculitis.
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Affiliation(s)
- Kimihiko Nakatani
- Department of Pathology, Nara Medical University Kashihara, Nara, Japan ; First Department of Internal Medicine, Nara Medical University Kashihara, Nara, Japan
| | - Shuhei Yoshimoto
- First Department of Internal Medicine, Nara Medical University Kashihara, Nara, Japan
| | - Osamu Asai
- First Department of Internal Medicine, Nara Medical University Kashihara, Nara, Japan
| | - Hirokazu Sakan
- First Department of Internal Medicine, Nara Medical University Kashihara, Nara, Japan
| | - Miho Terada
- Division of Pathogenomics, Department of Pathology, Ehime University Graduate School of Medicine To-on, Ehime, Japan
| | - Yoshihiko Saito
- First Department of Internal Medicine, Nara Medical University Kashihara, Nara, Japan
| | - Masato Nose
- Division of Pathogenomics, Department of Pathology, Ehime University Graduate School of Medicine To-on, Ehime, Japan
| | - Masayuki Iwano
- First Department of Internal Medicine, Nara Medical University Kashihara, Nara, Japan ; Division of Nephrology, Department of General Medicine, Faculty of Medical Sciences, University of Fukui Yoshida-gun, Fukui, Japan
| | - Noboru Konishi
- Department of Pathology, Nara Medical University Kashihara, Nara, Japan
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Flowers SA, Ali L, Lane CS, Olin M, Karlsson NG. Selected reaction monitoring to differentiate and relatively quantitate isomers of sulfated and unsulfated core 1 O-glycans from salivary MUC7 protein in rheumatoid arthritis. Mol Cell Proteomics 2013; 12:921-31. [PMID: 23457413 DOI: 10.1074/mcp.m113.028878] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023] Open
Abstract
Rheumatoid arthritis is a common and debilitating systemic inflammatory condition affecting up to 1% of the world's population. This study aimed to investigate the immunological significance of O-glycans in chronic arthritis at a local and systemic level. O-Glycans released from synovial glycoproteins during acute and chronic arthritic conditions were compared and immune-reactive glycans identified. The sulfated core 1 O-glycan (Galβ1-3GalNAcol) was immune reactive, showing a different isomeric profile in the two conditions. From acute reactive arthritis, three isomers could be sequenced, but in patients with chronic rheumatoid arthritis, only a single 3-Gal sulfate-linked isomer could be identified. The systemic significance of this glycan epitope was investigated using the salivary mucin MUC7 in patients with rheumatoid arthritis and normal controls. To analyze this low abundance glycan, a selected reaction monitoring (SRM) method was developed to differentiate and relatively quantitate the core 1 O-glycan and the sulfated core 1 O-glycan Gal- and GalNAc-linked isomers. The acquisition of highly sensitive full scan linear ion trap MS/MS spectra in addition to quantitative SRM data allowed the 3- and 6-linked Gal isomers to be differentiated. The method was used to relatively quantitate the core 1 glycans from MUC7 to identify any systemic changes in this carbohydrate epitope. A statistically significant increase in sulfation was identified in salivary MUC7 from rheumatoid arthritis patients. This suggests a potential role for this epitope in chronic inflammation. This study was able to develop an SRM approach to specifically identify and relatively quantitate sulfated core 1 isomers and the unsulfated structure. The expansion of this method may afford an avenue for the high throughput investigation of O-glycans.
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Affiliation(s)
- Sarah A Flowers
- Department of Medical Biochemistry, Institute of Biomedicine, University of Gothenburg, Medicinaregatan 9A, 405 30, Gothenburg, Sweden
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Liu S, Kiick K. Architecture effects on L-selectin shedding induced by polypeptide-based multivalent ligands. Polym Chem 2011; 2:1513-1522. [PMID: 23926449 DOI: 10.1039/c1py00063b] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Multivalent interactions between selectins and their ligands play key roles in mediating the rolling and tethering of leukocytes in the early steps of the inflammatory response, as well as in lymphocyte circulation. L-selectin shedding, which is the proteolytic cleavage of L-selectin, can be induced by L-selectin clustering through the binding of multivalent ligands to multiple L-selectin molecules, and it has been shown to regulate leukocyte rolling and subsequent integrin activation for firm adhesion. In this paper, we report the production of homogenous glycopolypeptides modified with a 3,6-disulfo-galactopyranoside equipped with a caproyl linker. The saccharide residue was chemically attached to various polypeptide backbones of differing architectures; the composition and purity of the sulfated glycopolypeptides was confirmed via1H-NMR spectroscopy, amino acid analysis (AAA), and electrophoretic analysis. The retention of the conformation of the polypeptide backbone was confirmed via circular dichroic spectroscopy. The shedding of l-selectin from the surface of Jurkat cells induced by these sulfated glycopolypeptides, determined via ELISA-based methods, varied based on differences in the architectures of the polypeptide scaffolds, suggesting opportunities for these strategies in probing cell-surface receptor arrays and directing cell signaling events.
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Affiliation(s)
- Shuang Liu
- Department of Materials Science and Engineering, University of Delaware, 201 DuPont Hall, Newark, Delaware, 19716, USA.
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Yu SY, Wu SW, Hsiao HH, Khoo KH. Enabling techniques and strategic workflow for sulfoglycomics based on mass spectrometry mapping and sequencing of permethylated sulfated glycans. Glycobiology 2009; 19:1136-49. [PMID: 19671626 DOI: 10.1093/glycob/cwp113] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Sulfate modifications on terminal epitopes of N- and O-glycans have increasingly been implicated as critical determinants mediating a diverse range of biological recognition functions. To address these low abundance but important sulfated glycans, and the sulfoglycome in general, further development of enrichment strategies and enabling mass spectrometry (MS)-based mapping techniques are needed. In this report, we demonstrate that the sulfated glycans, with and without additional sialylation, can be successfully permethylated by the sodium hydroxide slurry method and be distinguished from phosphorylated glycans by virtue of this derivatization. In conjunction with simple microscale postderivatization fractionation steps, permethyl derivatives fully retaining the negatively charged sulfate moiety and separated from the nonsulfated ones, can be efficiently detected and sequenced de novo by advanced MS/MS in the positive-ion mode. In particular, we show that the highly sequence and linkage informative high energy collision induced dissociation (CID) MS/MS afforded by MALDI-TOF/TOF can be extended to sulfoglycomic applications. The sulfated parent ion selected for CID MS/MS was found to mostly retain the sulfate moiety and therefore allow efficient fragmentation via the usual array of glycosidic, cross ring, and concerted double cleavages. Collectively, the optimized strategy enables a high sensitivity detection and critical mapping of the sulfoglycome such as the one derived from lymph node tissues or cell lines in both negative and positive-ion modes. Novel sulfated epitopes were identified from a crude mouse lymph node preparation, which fully attested to the practical utility of the methodology developed.
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Affiliation(s)
- Shin-Yi Yu
- Institute of Biochemical Sciences, National Taiwan University, Taipei 106, Taiwan
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Pazynina G, Sablina M, Mayzel M, Nasonov V, Tuzikov A, Bovin N. Chemical synthesis of 6(GlcNAc)- and 6(Gal)-O-sulfated SiaLe(X) tetrasaccharides in spacer-armed form. Glycobiology 2009; 19:1078-81. [PMID: 19584101 DOI: 10.1093/glycob/cwp093] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Practical synthesis of tetrasaccharide sulfates, 6((GlcNAc))-O-Su-SiaLe(X)-OCH(2)CH(2)CH(2)NH(2) and 6((Gal))-O-Su-SiaLe(X)-OCH(2)CH(2)CH(2)NH(2) (Su( )SO(3)H), selectin ligands, and leu- kocyte trafficking agents is presented. Both sulfates were synthesized starting from the same precursor, protected SiaLe(x), by the conventional procedures of carbohydrate chemistry. The sulfated SiaLe(x) derivative was modified at the spacer group to give 6((Gal))-O-Su-SiaLe(x)- OCH(2)CH(2)CH(2)NH-COCH(2)CH(2)C[triple bond]CH, convenient for "click chemistry" mode conjugation with an azido carrier, particularly, for the synthesis of an immunogen.
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Affiliation(s)
- Galina Pazynina
- Laboratory of Carbohydrate Chemistry, Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, 117997 Moscow, Russia
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Mehta P. Semi-dry protein transfer and immunodetection of P-selectin using an antibody to its C-terminal tag. Methods Mol Biol 2009; 536:229-235. [PMID: 19378062 DOI: 10.1007/978-1-59745-542-8_25] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
P-selectin is a multidomain glycoprotein expressed on activated endothelial cells. We previously expressed a recombinant form of P-selectin containing only its N-terminal lectin and EGF domains in CHO-K1 cells and showed that these two domains are sufficient to mediate ligand binding. We have now expressed the same construct in CHO-Lec1 cells that make truncated glycans. The uniform glycosylation in these cells should make it easier to crystallize this protein.
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Affiliation(s)
- Padmaja Mehta
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, Oklahoma City, OK, 73104, USA.
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12
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Karlsson NG, Thomsson KA. Salivary MUC7 is a major carrier of blood group I type O-linked oligosaccharides serving as the scaffold for sialyl Lewis x. Glycobiology 2008; 19:288-300. [PMID: 19043084 DOI: 10.1093/glycob/cwn136] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Isolation of salivary MUC7 with gel electrophoresis allowed analysis by LC-MS and LC-MS(2) of released O-linked oligosaccharides and a thorough description of the glycosylation of this molecule, where high-molecular-weight oligosaccharides up to the size of 2790 Da and with up to three sialic acid residues were identified. A common theme of these novel high abundant oligosaccharides on MUC7 showed that the C-3 branch of the oligosaccharides consisted of branched I-antigen type structural epitopes (GlcNAc beta 1-3(GlcNAc beta 1-6)Gal beta 1-), where the branch point was initiated on core 1 and core 2 galactose residues, and the branches were terminated by sialyl type 2 and sialyl Lewis x epitopes. Six sulfated sialylated oligosaccharides of low intensity were also identified, with the sulfate mainly on N-acetyl glucosamine residues located close to the reducing termini. One of these oligosaccharides was identified as a candidate for the high-affinity L-selectin ligand 6'-sulfo sialyl Lewis x. Neutral oligosaccharides and blood group antigens were found to be less abundant on MUC7 and the glycosylation appeared to be more preserved between individuals as compared to salivary MUC5B. This was illustrated by comparing the LC-MS spectra of MUC7 and MUC5B glycans from secretors (23 individuals) and nonsecretors (6 individuals). The data show that MUC7 provides a multivalent scaffold for sialylation, meeting the requirement for high-avidity binding via its glycosylation and mediator of the interaction between immune cells such as salivary neutrophils and oral bacteria.
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Affiliation(s)
- Niclas G Karlsson
- National University Ireland, School of Chemistry, Galway 091 756650, Ireland.
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Klopocki AG, Yago T, Mehta P, Yang J, Wu T, Leppänen A, Bovin NV, Cummings RD, Zhu C, McEver RP. Replacing a lectin domain residue in L-selectin enhances binding to P-selectin glycoprotein ligand-1 but not to 6-sulfo-sialyl Lewis x. J Biol Chem 2008; 283:11493-500. [PMID: 18250165 DOI: 10.1074/jbc.m709785200] [Citation(s) in RCA: 46] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Selectin-ligand interactions (bonds) mediate leukocyte rolling on vascular surfaces. The molecular basis for differential ligand recognition by selectins is poorly understood. Here, we show that substituting one residue (A108H) in the lectin domain of L-selectin increased its force-free affinity for a glycosulfopeptide binding site (2-GSP-6) on P-selectin glycoprotein ligand-1 (PSGL-1) but not for a sulfated-glycan binding site (6-sulfo-sialyl Lewis x) on peripheral node addressin. The increased affinity of L-selectinA108H for 2-GSP-6 was due to a faster on-rate and to a slower off-rate that increased bond lifetimes in the absence of force. Rather than first prolonging (catching) and then shortening (slipping) bond lifetimes, increasing force monotonically shortened lifetimes of L-selectinA108H bonds with 2-GSP-6. When compared with microspheres bearing L-selectin, L-selectinA108H microspheres rolled more slowly and regularly on 2-GSP-6 at low flow rates. A reciprocal substitution in P-selectin (H108A) caused faster microsphere rolling on 2-GSP-6. These results distinguish molecular mechanisms for L-selectin to bind to PSGL-1 and peripheral node addressin and explain in part the shorter lifetimes of PSGL-1 bonds with L-selectin than P-selectin.
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Affiliation(s)
- Arkadiusz G Klopocki
- Cardiovascular Biology Research Program, Oklahoma Medical Research Foundation, University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma 73104, USA
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Wu AM, Khoo KH, Yu SY, Yang Z, Kannagi R, Watkins WM. Glycomic mapping of pseudomucinous human ovarian cyst glycoproteins: Identification of Lewis and sialyl Lewis glycotopes. Proteomics 2007; 7:3699-717. [PMID: 17880005 DOI: 10.1002/pmic.200700356] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Expression of sialyl Lewis x (sLe(x)) and sialyl Lewis a (sLe(a)) on cell-surface glycoproteins endows cells with the ability to adhere to E-, P-, and L-selectins present on endothelia, platelets, or leukocytes. Special arrangements of these glycotopes in cancers are thought to play a key role in metastasis. Previous studies have mostly described membrane-bound sLe(x) and sLe(a) activities. In this report, the major O-glycans of the secreted human ovarian cyst sialoglycoproteins from a Le(a+) nonsecretor individual (human ovarian cyst sample 350) were characterized by MS/MS analyses and immuno-/lectin-chemical assays. The results showed that HOC 350 carries a large number of epitopes for sLe(x), sLe(a), and Le(a) reactive antibodies. Advanced MS/MS sequencing coupled with mild periodate oxidation and exoglycosidase digestions further revealed that the O-glycans from HOC 350 are mostly of core 1 and 2 structures, extended and branched on the 3-arm with both type I and type II chains, complete with variable degrees of terminal sialylation and/or fucosylation to yield the sLe(x) or sLe(a) epitopes. Thus, the underlying core and peripheral backbone structures are similar to that of a previously proposed composite structural model for nonsialylated human ovarian cysts O-glycans, but with some notable distinguishing structural features in addition to sialylation.
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Affiliation(s)
- Albert M Wu
- Glyco-Immunochemistry Research Laboratory, Institute of Molecular and Cellular Biology, Chang-Gung University, Tao-yuan, Taiwan
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Lou J, Yago T, Klopocki AG, Mehta P, Chen W, Zarnitsyna VI, Bovin NV, Zhu C, McEver RP. Flow-enhanced adhesion regulated by a selectin interdomain hinge. ACTA ACUST UNITED AC 2006; 174:1107-17. [PMID: 17000883 PMCID: PMC2064400 DOI: 10.1083/jcb.200606056] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/05/2023]
Abstract
L-selectin requires a threshold shear to enable leukocytes to tether to and roll on vascular surfaces. Transport mechanisms govern flow-enhanced tethering, whereas force governs flow-enhanced rolling by prolonging the lifetimes of L-selectin–ligand complexes (catch bonds). Using selectin crystal structures, molecular dynamics simulations, site-directed mutagenesis, single-molecule force and kinetics experiments, Monte Carlo modeling, and flow chamber adhesion studies, we show that eliminating a hydrogen bond to increase the flexibility of an interdomain hinge in L-selectin reduced the shear threshold for adhesion via two mechanisms. One affects the on-rate by increasing tethering through greater rotational diffusion. The other affects the off-rate by strengthening rolling through augmented catch bonds with longer lifetimes at smaller forces. By forcing open the hinge angle, ligand may slide across its interface with L-selectin to promote rebinding, thereby providing a mechanism for catch bonds. Thus, allosteric changes remote from the ligand-binding interface regulate both bond formation and dissociation.
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Affiliation(s)
- Jizhong Lou
- Institute for Bioengineering and Bioscience, Georgia Institute of Technology, Atlanta, GA 30332, USA
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Abstract
Leukocyte rolling is an important step for the successful recruitment of leukocytes into tissue and occurs predominantly in inflamed microvessels and in high endothelial venules of secondary lymphoid organs. Leukocyte rolling is mediated by a group of C-type lectins, termed selectins. Three different selectins have been identified - P-, E- and L-selectin - which recognize and bind to crucial carbohydrate determinants on selectin ligands. Among selectin ligands, P-selectin glycoprotein ligand-1 is the main inflammatory selectin ligand, showing binding to all three selectins under in vivo conditions. Functional relevant selectin ligands expressed on high endothelial venules of lymphoid tissue are less clearly defined at the protein level. However, high endothelial venule-expressed selectin ligands were instrumental in uncovering the crucial role of post-translational modifications for selectin ligand activity. Several glycosyltransferases, such as core 2 beta1,6-N-acetylglucosaminyltransferase-I, beta1,4-galactosyltransferases, alpha1,3-fucosyltransferases and alpha2,3-sialyltransferases have been described to participate in the synthesis of core 2 decorated O-glycan structures carrying the tetrasaccharide sialyl Lewis X, a carbohydrate determinant on selectin ligands with binding activity to all three selectins. In addition, modifications, such as carbohydrate or tyrosine sulfation, were also found to contribute to the synthesis of functional selectin ligands.
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Affiliation(s)
- Markus Sperandio
- University Children's Hospital Heidelberg, Division of Neonatal Medicine, University of Heidelberg, Germany.
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