Synthesis of a multivalent display of a CD22-binding trisaccharide

Yang, Zujing; Puffer, E; Pontrello, Jason K.; Kiessling, Laura L.

doi:10.1016/s0008-6215(02)00270-7

Cited by 40 publications

(37 citation statements)

References 57 publications

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“…Specifically, when CD22-positive cells are exposed to the types of monovalent CD22 ligands that occur naturally, no binding is detected (18)(19)(20). Even multivalent presentations of these ligands fail to interact with CD22 (18)(19)(20). These observations are consistent with studies indicating that CD22 binds only weakly to naturally occurring carbohydrate ligands (21).…”

supporting

confidence: 85%

“…The antigen we incorporated, 2,4-dinitrophenyl (DNP), is convenient because it can be readily attached to the polymer backbone and a murine B cell line displaying a DNP-specific BCR is available (A20.2J HL TNP denoted A20HL) (35,36). The design of the CD22 ligands was guided by our previous studies indicating that a polymer bearing a sialic acid-terminated trisaccharide can engage CD22 on the cell-surface (20). Using these components and precedents, we synthesized polymers that can bind to cells through the BCR alone (1), CD22 alone (2), or both (3).…”

Section: Resultsmentioning

confidence: 99%

“…Cis interactions between CD22 and proximal glycoconjugates can mask the coreceptor to exogenous (trans) ligands. Specifically, when CD22-positive cells are exposed to the types of monovalent CD22 ligands that occur naturally, no binding is detected (18)(19)(20). Even multivalent presentations of these ligands fail to interact with CD22 (18-20).…”

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confidence: 99%

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Sialylated multivalent antigens engage CD22in transand inhibit B cell activation

Courtney¹,

Puffer²,

Pontrello

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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121

178

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CD22 is an inhibitory coreceptor on the surface of B cells that attenuates B cell antigen receptor (BCR) signaling and, therefore, B cell activation. Elucidating the molecular mechanisms underlying the inhibitory activity of CD22 is complicated by the ubiquity of CD22 ligands. Although antigens can display CD22 ligands, the receptor is known to bind to sialylated glycoproteins on the cell surface. The propinquity of CD22 and cell-surface glycoprotein ligands has led to the conclusion that the inhibitory properties of the receptor are due to cis interactions. Here, we examine the functional consequences of trans interactions by employing sialylated multivalent antigens that can engage both CD22 and the BCR. Exposure of B cells to sialylated antigens results in the inhibition of key steps in BCR signaling. These results reveal that antigens bearing CD22 ligands are powerful suppressors of B cell activation. The ability of sialylated antigens to inhibit BCR signaling through trans CD22 interactions reveals a previously unrecognized role for the Siglec-family of receptors as modulators of immune signaling.B cell antigen receptor ͉ multivalency ͉ sialic acid ͉ siglec ͉ autoimmunity T he initiation of an immune response or the prevention of autoimmunity depends upon the ability of the B cell antigen receptor (BCR) to transmit signals that positively or negatively regulate B lymphocyte survival, proliferation, and differentiation (1). To avoid detrimental autoimmune responses, a means of differentiating between foreign and self-antigens is required; coreceptors that modulate BCR signaling can ensure that these distinctions are made. CD22 is an inhibitory coreceptor that can attenuate BCR signaling (2, 3). CD22 null mice possess hyperresponsive B cells (4), illustrating a role for CD22 in establishing a threshold for B cell activation. Specifically, an increase in intracellular Ca 2ϩ ion concentration is a hallmark of B cell activation (5, 6), and B cells isolated from CD22 null mice display increased Ca 2ϩ flux in response to antigen (4, 7). Thus, loss of CD22 results in a lowering of the threshold for B cell activation. Other data also support this conclusion: CD22 null mice exhibit increased serum IgM concentrations, decreased surface IgM levels on peripheral B cells, increased induction of apoptosis in response to BCR crosslinking, and increased serum autoantibody titers (8). These observations are consistent with the loss of CD22 leading to increased sensitivity and chronic B cell activation.The process of B cell activation ensues upon binding of multivalent antigen to the BCR. Antigen-induced clustering elicits phosphorylation of the cytoplasmic immunoreceptor tyrosinebased activation motifs (ITAMs), which are present in the BCRassociated signaling proteins Ig␣/␤. The phosphorylation reaction is catalyzed by Src-family kinases such as Lyn. Upon phosphorylation of the BCR components, Syk kinase is recruited to the BCR signaling complex (9). Syk is essential for propagating BCR signaling (10, 11). It acts along with...

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supporting

confidence: 85%

Section: Resultsmentioning

confidence: 99%

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Sialylated multivalent antigens engage CD22in transand inhibit B cell activation

Courtney¹,

Puffer²,

Pontrello

et al. 2009

Proc. Natl. Acad. Sci. U.S.A.

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121

178

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“…Several reports (25,26,28,39,40) have evaluated the specificity of one or several siglecs using competitive inhibition of multivalent binding assays by monovalent sialosides analogous to the studies reported here. However, most have used multivalent assays based on binding of siglecs to sialosides attached to a polyacrylamide or other polymeric carrier (1,34,37,49,(52)(53)(54)(55)(57)(58)(59), to gangliosides adsorbed to microtiter plates (30,36,38) or to neo-glycoprotein conjugates (27,28).…”

Section: Figmentioning

confidence: 99%

Sialoside Specificity of the Siglec Family Assessed Using Novel Multivalent Probes

Blixt¹,

Collins²,

Nieuwenhof³

et al. 2003

Journal of Biological Chemistry

209

111

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Ten of the 11 known human siglecs or their murine orthologs have been evaluated for their specificity for over 25 synthetic sialosides representing most of the major sequences terminating carbohydrate groups of glycoproteins and glycolipids. Analysis has been performed using a novel multivalent platform comprising biotinylated sialosides bound to a streptavidin-alkaline phosphatase conjugate. Each siglec was found to have a unique specificity for binding 16 different sialoside-streptavidin-alkaline phosphatase probes. The relative affinities of monovalent sialosides were assessed for each siglec in competitive inhibition studies. The quantitative data obtained allows a detailed analysis of each siglec for the relative importance of sialic acid and the penultimate oligosaccharide sequence on binding affinity and specificity. Most remarkable was the finding that myelin-associated glycoprotein (Siglec-4) binds with 500 -10,000-fold higher affinity to a series of mono-and di-sialylated derivatives of the O-linked T-antigen (Gal␤(1-3)-GalNAc␣OThr) as compared with ␣-methyl-NeuAc.

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“…13 This linkage can undergo hydrolysis upon cellular uptake. 14 Though this lability could be valuable for cargo delivery, it complicates monitoring polymer uptake and trafficking.…”

Section: Introductionmentioning

confidence: 99%

A Polymeric Domain That Promotes Cellular Internalization

Kolonko

Kiessling

2008

J. Am. Chem. Soc.

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Polymers have emerged as powerful biological tools; however, their ability to gain access to the intracellular environment is limited. To expand the biological utility of polymer scaffolds, we have synthesized an internalization domain using the ring-opening metathesis polymerization (ROMP). A polymer functionalized with guanidinium groups is effectively internalized by cells and localized in both vesicles and the cytoplasm. Because the synthesis of such materials is modular, we anticipate that compounds of this type can be fashioned that facilitate the delivery of cargo via end-cap derivatization or block copolymer synthesis.New synthetic methods are fueling the use of polymers in biology. 1 Indeed, polymers can function as therapeutics, 1a,c biomaterials, 1b imaging agents, 2 and multivalent biological probes. 3 The growing applications of polymers stem from the ability to tailor their properties. For example, the molecular masses of polymers can be controlled, thereby modulating their serum half-life, cell or tissue targeting, and binding avidity. In addition, because polymers are modular, a wide range of different functionality can be introduced to endow them with tailored bulk properties and the ability to engage in specific biological recognition events. One disadvantage of polymers, however, is that their ability to gain access to cytoplasmic and nuclear targets is limited. Because of their high molecular weights and functionalities, most polymers are cell impermeable. We reasoned that the utility of bioactive polymers could be expanded by devising a general method for promoting their cellular internalization. To this end, we envisioned generating polymers that contain an artificial translocation domain, or ATD.The design of our polymer ATD was guided by the features of known internalization agents. Small, highly cationic peptides, including TAT and oligoarginine, can promote cellular uptake. 4 These internalization agents, often referred to as protein transduction domains (PTDs) or cell-penetrating peptides, can facilitate the intracellular delivery of compounds ranging from small molecules to proteins to nanoparticles. In addition, PTD mimics, such as β-peptides and peptoids, have been described. 5 The structural diversity of internalization agents indicates that an optimal number of guanidinium groups, not backbone composition, is a primary requirement for uptake. The model for uptake involves association of the guanidinium groups with the sulfate groups of cell-surface glycosaminoglycans, such as heparan sulfate. 6 This association is followed by internalization via an endocytic pathway. Because this pathway depends upon Coulombic interactions with ubiquitous proteoglycans and not the presence of a specific receptor, compounds that exploit this route can be taken up by a variety of cell types. Thus, to develop a general route to ATDs with these properties, we envisioned appending guanidinium groups to a polymer backbone that can be synthesized in one step. The optimal number of guanidinium...

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Synthesis of a multivalent display of a CD22-binding trisaccharide

Cited by 40 publications

References 57 publications

Sialylated multivalent antigens engage CD22in transand inhibit B cell activation

Sialylated multivalent antigens engage CD22in transand inhibit B cell activation

Sialoside Specificity of the Siglec Family Assessed Using Novel Multivalent Probes

A Polymeric Domain That Promotes Cellular Internalization

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