scholarly journals Detection of Human CD38 Using Variable Lymphocyte Receptor (VLR) Tetramers

Cells ◽  
2020 ◽  
Vol 9 (4) ◽  
pp. 950
Author(s):  
Srijit Khan ◽  
Yanling Liu ◽  
Laura M. Ernst ◽  
Leslie Y. T. Leung ◽  
Patrick Budylowski ◽  
...  
Keyword(s):  
Human Plasma ◽  
Plasma Cells ◽  
Specific Binding ◽  
Single Step ◽  
Cell Surface Receptor ◽  
Color Flow ◽  
Surface Receptor ◽  
Increased Sensitivity ◽  
Preferential Recognition ◽  
Variable Lymphocyte Receptor

CD38 is a multifunctional cell surface receptor expressed on multiple cell lineages of hematopoietic origin with high levels of expression on human plasma cells. Previously, we isolated the monoclonal variable lymphocyte receptor B (VLRB) MM3 antibody from the evolutionarily distant sea lamprey, which recognized the CD38 ectoenzyme exclusively on human plasma cells in a manner that correlated with CD38 enzymatic activity. The plasma cell-specific binding of VLRB MM3 contrasts with the broad pattern of expression of CD38-determined conventional antibodies specific for this antigen. In an effort to facilitate the application of this unique reagent in combination with conventional antibody panels, we explored a strategy to generate VLRB MM3 tetramers. The resulting reagent maintained the threshold-based recognition of CD38. Increased sensitivity achieved with VLRB MM3 tetramers also showed preferential recognition of germinal center centroblasts over centrocytes. VLRB MM3 tetramers thus provided a unique and versatile single-step staining reagent for the detection of human CD38 that is readily incorporated into multi-color flow cytometry panels.

Identification of the SV2 protein receptor-binding site of botulinum neurotoxin type E

2013 ◽  
Vol 453 (1) ◽  
pp. 37-47 ◽  
Author(s):  
Stefan Mahrhold ◽  
Jasmin Strotmeier ◽  
Consuelo Garcia-Rodriguez ◽  
Jianlong Lou ◽  
James D. Marks ◽  
...  
Keyword(s):  
Binding Site ◽  
Synaptic Vesicle ◽  
Specific Binding ◽  
Cell Surface Receptor ◽  
Vesicle Membrane ◽  
Receptor Binding Site ◽  
Binding Interface ◽  
Protein Receptor ◽  
Surface Receptor ◽  
Extended Surface

The highly specific binding and uptake of BoNTs (botulinum neurotoxins; A–G) into peripheral cholinergic motoneurons turns them into the most poisonous substances known. Interaction with gangliosides accumulates the neurotoxins on the plasma membrane and binding to a synaptic vesicle membrane protein leads to neurotoxin endocytosis. SV2 (synaptic vesicle glycoprotein 2) mediates the uptake of BoNT/A and /E, whereas Syt (synaptotagmin) is responsible for the endocytosis of BoNT/B and /G. The Syt-binding site of the former was identified by co-crystallization and mutational analyses. In the present study we report the identification of the SV2-binding interface of BoNT/E. Mutations interfering with SV2 binding were located at a site that corresponds to the Syt-binding site of BoNT/B and at an extended surface area located on the back of the conserved ganglioside-binding site, comprising the N- and C-terminal half of the BoNT/E-binding domain. Mutations impairing the affinity also reduced the neurotoxicity of full-length BoNT/E at mouse phrenic nerve hemidiaphragm preparations demonstrating the crucial role of the identified binding interface. Furthermore, we show that a monoclonal antibody neutralizes BoNT/E activity because it directly interferes with the BoNT/E–SV2 interaction. The results of the present study suggest a novel mode of binding for BoNTs that exploit SV2 as a cell surface receptor.

Regulation of the Urokinase Receptor by Its Plasminogen Activator

1991 ◽  
Vol 66 (06) ◽  
pp. 678-683 ◽  
Author(s):  
W Hollas ◽  
D Boyd
Keyword(s):  
Molecular Weight ◽  
Plasminogen Activator ◽  
Specific Binding ◽  
Cell Surface Receptor ◽  
Specific Cell ◽  
Acid Pretreatment ◽  
Ample Evidence ◽  
Surface Receptor ◽  
A Chain ◽  
The Uk

SummaryThere is now ample evidence that the proteolytic action of urokinase (UK) is potentiated by a specific cell surface receptor. The present study was undertaken to assess the role of UK as a modulator of its receptor. GEO colonic cells, which secrete relatively low levels of UK (≃0.1 nM/72 h per 106 cells) and display approximately 104 receptors per cell, 10% of which are "tagged" with the endogenous plasminogen activator (PA), was selected for the study. A 90% reduction in the specific binding of radioactive DFP-UK was observed for cells cultivated in the presence of two-chain (TC) UK (M r 55,000). This only partly reflected occupation of the receptors with UK supplied in the culture medium, since the specific binding of the radioligand was still reduced by 60% after an acid pretreatment, which dissociates receptor-bound UK. The reduction in radioactive DFP-UK binding to cells treated with high molecular weight UK, either in the single or two-chain form, was both concentration and time dependent. Maximum reductions (70%) were achieved by treatment of the cells for 24 h with 1 nM of the plasminogen activator. In contrast, low molecular weight UK, which lacks part of the UK A chain, had no effect on ligand binding. Attenuation of radioactive DFP-UK binding to UK treated GEO cells was a consequence of a 60% reduction in the number of binding sites. Treatment of GEO cells with an antibody, which blocks the binding of endogenous UK to its receptor, augmented radioactive DFP-UK binding by two-fold. These data indicate that for one colonic cell line, at least, UK down-regulates its own binding site subsequent to it being bound to the receptor.

scholarly journals Exogenous Cyclic AMP, Cholera Toxin, and Endotoxin Induce Expression of the Lipopolysaccharide Receptor CD14 in Murine Bone Marrow Cells: Role of Purinoreceptors

1999 ◽  
Vol 6 (6) ◽  
pp. 885-890 ◽  
Author(s):  
Thierry Pedron ◽  
Robert Girard ◽  
Richard Chaby
Keyword(s):  
Bone Marrow ◽  
Cyclic Amp ◽  
Cholera Toxin ◽  
Bone Marrow Cells ◽  
Specific Binding ◽  
Cell Surface Receptor ◽  
Intracellular Camp ◽  
Purine Derivatives ◽  
Murine Bone Marrow ◽  
Surface Receptor

ABSTRACT Little is known about the mechanisms of lipopolysaccharide (LPS) signaling in immature cells that do not express the LPS receptor CD14 yet. Bone marrow granulocytes do not constitutively express CD14 but can be stimulated by low doses of LPS in the absence of serum and then express an inducible form of LPS receptor (iLpsR). We show that in addition to LPS, cholera toxin (CT) and various cyclic AMP (cAMP) analogs can also induce the expression of iLpsR, which was identified as CD14. Induction was independent of intracellular cAMP. The hypothesis that cAMP analogs act via a cell surface receptor was suggested by the unresponsiveness of trypsin-treated cells to these inducers and by the specific binding of [3H]cAMP to the cells. This binding was not inhibited by LPS or CT but was inhibited by various purine derivatives. However, the receptor involved is not a conventional purinoreceptor since both an agonist and an antagonist of such receptors were able to induce iLpsR expression. The results suggest that cAMP analogs and other purine derivatives induce iLpsR after interaction with an unconventional, trypsin-sensitive, purinoreceptor distinct from LPS and CT receptors.

scholarly journals Carbohydrate recognition in the peripheral nervous system: a calcium-dependent membrane binding site for HNK-1 reactive glycolipids potentially involved in Schwann cell adhesion.

1993 ◽  
Vol 121 (2) ◽  
pp. 397-408 ◽  
Author(s):  
L K Needham ◽  
R L Schnaar
Keyword(s):  
Nervous System ◽  
Cell Adhesion ◽  
Schwann Cell ◽  
Binding Site ◽  
Peripheral Nervous System ◽  
Specific Binding ◽  
Binding Activity ◽  
Cell Surface Receptor ◽  
Calcium Dependent ◽  
Surface Receptor

The carbohydrate determinants recognized by the HNK-1 antibody are potential cell-cell recognition ligands in the peripheral nervous system (PNS). The HNK-1 reactive sulfoglucuronylneolacto (SGNL) glycolipids specifically support Schwann cell adhesion, suggesting the presence of a cell surface receptor specific for SGNL-oligosaccharides. We directly probed PNS membranes for receptors complementary to SGNL determinants using a synthetic radioligand consisting of radioiodinated serum albumin derivatized with multiple SGNL-oligosaccharides. A high-affinity, saturable, calcium-dependent binding site for this ligand was found in PNS myelin membranes. Binding activity was carbohydrate-specific (most potently inhibited by SGNL-lipids compared to other glycolipids) and PNS-specific (absent from comparable central nervous system membranes). The SGNL-specific binding activity on PNS membranes reported here may be involved in peripheral myelination or myelin stabilization.

scholarly journals Decreased nonspecific adhesivity, receptor-targeted therapeutic nanoparticles for primary and metastatic breast cancer

2020 ◽  
Vol 6 (3) ◽  
pp. eaax3931 ◽  
Author(s):  
Jimena G. Dancy ◽  
Aniket S. Wadajkar ◽  
Nina P. Connolly ◽  
Rebeca Galisteo ◽  
Heather M. Ames ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Cell Surface ◽  
Tumor Cell ◽  
Specific Binding ◽  
Metastatic Breast ◽  
Cell Surface Receptor ◽  
Surface Receptor ◽  
Specific Uptake ◽  
Effective Development ◽  
The Brain

Development of effective tumor cell–targeted nanodrug formulations has been quite challenging, as many nanocarriers and targeting moieties exhibit nonspecific binding to cellular, extracellular, and intravascular components. We have developed a therapeutic nanoparticle formulation approach that balances cell surface receptor-specific binding affinity while maintaining minimal interactions with blood and tumor tissue components (termed “DART” nanoparticles), thereby improving blood circulation time, biodistribution, and tumor cell–specific uptake. Here, we report that paclitaxel (PTX)–DART nanoparticles directed to the cell surface receptor fibroblast growth factor–inducible 14 (Fn14) outperformed both the corresponding PTX-loaded, nontargeted nanoparticles and Abraxane, an FDA-approved PTX nanoformulation, in both a primary triple-negative breast cancer (TNBC) model and an intracranial model reflecting TNBC growth following metastatic dissemination to the brain. These results provide new insights into methods for effective development of therapeutic nanoparticles as well as support the continued development of the DART platform for primary and metastatic tumors.

scholarly journals CD38 Deficiency Ameliorates Chronic Graft-Versus-Host Disease Murine Lupus via a B-Cell-Dependent Mechanism

2021 ◽  
Vol 12 ◽  
Author(s):  
África Martínez-Blanco ◽  
Marilú Domínguez-Pantoja ◽  
María Botía-Sánchez ◽  
Sonia Pérez-Cabrera ◽  
Nerea Bello-Iglesias ◽  
...  
Keyword(s):  
B Cells ◽  
Plasma Cells ◽  
Serum Levels ◽  
Mouse Cell ◽  
Treg Cells ◽  
Cell Surface Receptor ◽  
Type I ◽  
Spleen Cells ◽  
Host Disease ◽  
Surface Receptor

The absence of the mouse cell surface receptor CD38 in Cd38−/− mice suggests that this receptor acts as a positive regulator of inflammatory and autoimmune responses. Here, we report that, in the context of the chronic graft-versus-host disease (cGVHD) lupus inducible model, the transfer of B6.C-H2bm12/KhEg(bm12) spleen cells into co-isogenic Cd38−/− B6 mice causes milder lupus-like autoimmunity with lower levels of anti-ssDNA autoantibodies than the transfer of bm12 spleen cells into WT B6 mice. In addition, significantly lower percentages of Tfh cells, as well as GC B cells, plasma cells, and T-bet+CD11chi B cells, were observed in Cd38−/− mice than in WT mice, while the expansion of Treg cells and Tfr cells was normal, suggesting that the ability of Cd38−/− B cells to respond to allogeneic help from bm12 CD4+ T cells is greatly diminished. The frequencies of T-bet+CD11chi B cells, which are considered the precursors of the autoantibody-secreting cells, correlate with anti-ssDNA autoantibody serum levels, IL-27, and sCD40L. Proteomics profiling of the spleens from WT cGVHD mice reflects a STAT1-driven type I IFN signature, which is absent in Cd38−/− cGVHD mice. Kidney, spleen, and liver inflammation was mild and resolved faster in Cd38−/− cGVHD mice than in WT cGVHD mice. We conclude that CD38 in B cells functions as a modulator receptor that controls autoimmune responses.

scholarly journals Human Copper-Containing Amine Oxidases in Drug Design and Development

Molecules ◽  
2020 ◽  
Vol 25 (6) ◽  
pp. 1293 ◽  
Author(s):  
Serhii Vakal ◽  
Sirpa Jalkanen ◽  
Käthe M. Dahlström ◽  
Tiina A. Salminen
Keyword(s):  
Amine Oxidase ◽  
Inflammatory Diseases ◽  
Specific Binding ◽  
Mammalian Species ◽  
Model Organism ◽  
Cell Surface Receptor ◽  
Inhibitor Design ◽  
Surface Receptor ◽  
Targeted Inhibitors ◽  
Vascular Adhesion

Two members of the copper-containing amine oxidase family are physiologically important proteins: (1) Diamine oxidase (hDAO; AOC1) with a preference for diamines is involved in degradation of histamine and (2) Vascular adhesion protein-1 (hVAP-1; AOC3) with a preference for monoamines is a multifunctional cell-surface receptor and an enzyme. hVAP-1-targeted inhibitors are designed to treat inflammatory diseases and cancer, whereas the off-target binding of the designed inhibitors to hDAO might result in adverse drug reactions. The X-ray structures for both human enzymes are solved and provide the basis for computer-aided inhibitor design, which has been reported by several research groups. Although the putative off-target effect of hDAO is less studied, computational methods could be easily utilized to avoid the binding of VAP-1-targeted inhibitors to hDAO. The choice of the model organism for preclinical testing of hVAP-1 inhibitors is not either trivial due to species-specific binding properties of designed inhibitors and different repertoire of copper-containing amine oxidase family members in mammalian species. Thus, the facts that should be considered in hVAP-1-targeted inhibitor design are discussed in light of the applied structural bioinformatics and structural biology approaches.

scholarly journals Structure-function studies on human retinol-binding protein using site-directed mutagenesis

1994 ◽  
Vol 300 (2) ◽  
pp. 437-442 ◽  
Author(s):  
A Sivaprasadarao ◽  
J B Findlay
Keyword(s):  
Cell Surface ◽  
Specific Binding ◽  
Binding Protein ◽  
Specific Interaction ◽  
Binding Activity ◽  
Site Directed Mutagenesis ◽  
Retinol Binding Protein ◽  
Cell Surface Receptor ◽  
Directed Mutagenesis ◽  
Surface Receptor

Retinol-binding protein (RBP) transports vitamin A in the plasma. It consists of eight anti-parallel beta-strands (A to H) that fold to form an orthogonal barrel. The loops connecting the strands A and B, C and D, and E and F form the entrance to the binding site in the barrel. The retinol molecule is found deep inside this barrel. Apart from its specific interaction with retinol, RBP is involved in two other molecular-recognition properties, that is it binds to transthyretin (TTR), another serum protein, and to a cell-surface receptor. Using site-directed mutagenesis, specific changes were made to the loop regions of human RBP and the resultant mutant proteins were tested for their ability to bind to retinol, to TTR and to the RBP receptor. While all the variants retained their ability to bind retinol, that in which residues 92 to 98 of the loop E-F were deleted completely lost its ability to interact with TTR, but retained some binding activity for the receptor. In contrast, the double mutant in which leucine residues at positions 63 and 64 of the loop C-D were changed to arginine and serine respectively partially retained its TTR-binding ability, but completely lost its affinity for the RBP receptor. Mutation of Leu-35 of loop A-B to valine revealed no apparent effect on any of the binding activities of RBP. However, substitution of leucine for proline at position 35 markedly reduced the affinity of the protein for TTR, but showed no apparent change in its receptor-binding activity. These results demonstrate that RBP interacts with both TTR and the receptor via loops C-D and E-F. The binding sites, however, are overlapping rather than identical. RBP also appears to make an additional contact with TTR via its loop A-B. A further implication of these results is that RBP, when bound to TTR, cannot bind simultaneously to the receptor. This observation is consistent with our previously proposed mechanism for delivery of retinol to target tissues [Sivaprasadarao and Findlay (1988) Biochem. J. 255, 571-579], according to which retinol delivery involves specific binding of RBP to the cell-surface receptor, an interaction that triggers release of retinol from RBP to the bound cell rather than internalization of retinol-RBP complex.

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