scholarly journals Impaired Differentiation of Osteoclasts in TREM-2–deficient Individuals

2003 ◽  
Vol 198 (4) ◽  
pp. 645-651 ◽  
Author(s):  
Marina Cella ◽  
Cecilia Buonsanti ◽  
Carey Strader ◽  
Takayuki Kondo ◽  
Andrea Salmaggi ◽  
...  
Keyword(s):  
Brain Function ◽  
Critical Role ◽  
Cell Surface Receptor ◽  
Genetic Defects ◽  
Bone Modeling ◽  
Bone Cysts ◽  
Presenile Dementia ◽  
Surface Receptor ◽  
Resorptive Activity

TREM-2 is an immunoglobulin-like cell surface receptor associated with DAP12/KARAP that activates monocyte-derived dendritic cells (DCs) in vitro. Recently, it has been shown that genetic defects of human DAP12/KARAP and TREM-2 result in a rare syndrome characterized by bone cysts and presenile dementia called Nasu-Hakola disease. This observation suggests that TREM-2 may function in myeloid cells other than DCs, most probably osteoclasts (OCs) and microglial cells, which are involved in bone modeling and brain function. Consistent with this prediction, here we show that OC differentiation is dramatically arrested in TREM-2–deficient patients, resulting in large aggregates of immature OCs that exhibit impaired bone resorptive activity. These results demonstrate a critical role for TREM-2 in the differentiation of mononuclear myeloid precursors into functional multinucleated OCs.

scholarly journals A novel pathway of LPS uptake through syndecan-1 leading to pyroptotic cell death

eLife ◽  
2018 ◽  
Vol 7 ◽  
Author(s):  
Shigetoshi Yokoyama ◽  
Yan Cai ◽  
Miyuki Murata ◽  
Takeshi Tomita ◽  
Mitsuhiro Yoneda ◽  
...  
Keyword(s):  
Cell Death ◽  
Cancer Cells ◽  
Immune Cells ◽  
Critical Role ◽  
Underlying Mechanism ◽  
Innate Immune ◽  
Cell Surface Receptor ◽  
Innate Immune Cells ◽  
Surface Receptor

Intracellular lipopolysaccharide (LPS) triggers the non-canonical inflammasome pathway, resulting in pyroptosis of innate immune cells. In addition to its well-known proinflammatory role, LPS can directly cause regression of some tumors, although the underlying mechanism has remained unknown. Here we show that secretoglobin(SCGB)3A2, a small protein predominantly secreted in airways, chaperones LPS to the cytosol through the cell surface receptor syndecan-1; this leads to pyroptotic cell death driven by caspase-11. SCGB3A2 and LPS co-treatment significantly induced pyroptosis of macrophage RAW264.7 cells and decreased cancer cell proliferation in vitro, while SCGB3A2 treatment resulted in reduced progression of xenograft tumors in mice. These data suggest a conserved function for SCGB3A2 in the innate immune system and cancer cells. These findings demonstrate a critical role for SCGB3A2 as an LPS delivery vehicle; they reveal one mechanism whereby LPS enters innate immune cells leading to pyroptosis, and they clarify the direct effect of LPS on cancer cells.

scholarly journals A high-throughput screen for TMPRSS2 expression identifies FDA-approved compounds that can limit SARS-CoV-2 entry

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yanwen Chen ◽  
Travis B. Lear ◽  
John W. Evankovich ◽  
Mads B. Larsen ◽  
Bo Lin ◽  
...  
Keyword(s):  
Rational Design ◽  
Surface Expression ◽  
In Vitro Models ◽  
Lung Epithelial Cells ◽  
Cell Surface Receptor ◽  
Pharmacokinetic Data ◽  
Drug Induced ◽  
Global Pandemic ◽  
Surface Receptor

AbstractSARS-CoV-2 (2019-nCoV) is the pathogenic coronavirus responsible for the global pandemic of COVID-19 disease. The Spike (S) protein of SARS-CoV-2 attaches to host lung epithelial cells through the cell surface receptor ACE2, a process dependent on host proteases including TMPRSS2. Here, we identify small molecules that reduce surface expression of TMPRSS2 using a library of 2,560 FDA-approved or current clinical trial compounds. We identify homoharringtonine and halofuginone as the most attractive agents, reducing endogenous TMPRSS2 expression at sub-micromolar concentrations. These effects appear to be mediated by a drug-induced alteration in TMPRSS2 protein stability. We further demonstrate that halofuginone modulates TMPRSS2 levels through proteasomal-mediated degradation that involves the E3 ubiquitin ligase component DDB1- and CUL4-associated factor 1 (DCAF1). Finally, cells exposed to homoharringtonine and halofuginone, at concentrations of drug known to be achievable in human plasma, demonstrate marked resistance to SARS-CoV-2 infection in both live and pseudoviral in vitro models. Given the safety and pharmacokinetic data already available for the compounds identified in our screen, these results should help expedite the rational design of human clinical trials designed to combat active COVID-19 infection.

scholarly journals ABD-Derived Protein Blockers of Human IL-17 Receptor A as Non-IgG Alternatives for Modulation of IL-17-Dependent Pro-Inflammatory Axis

2018 ◽  
Vol 19 (10) ◽  
pp. 3089 ◽  
Author(s):  
Marie Hlavničková ◽  
Milan Kuchař ◽  
Radim Osička ◽  
Lucie Vaňková ◽  
Hana Petroková ◽  
...  
Keyword(s):  
Cell Surface ◽  
Clinical Manifestations ◽  
Cell Surface Receptor ◽  
Enzyme Linked Immunosorbent Assay ◽  
Interleukin 17 ◽  
Normal Human Skin ◽  
High Affinity ◽  
Th 17 ◽  
Surface Receptor

Interleukin 17 (IL-17) and its cognate receptor A (IL-17RA) play a crucial role in Th17 cells-mediated pro-inflammatory pathway and pathogenesis of several autoimmune disorders including psoriasis. IL-17 is mainly produced by activated Th-17 helper cells upon stimulation by IL-23 and, via binding to its receptors, mediates IL-17-driven cell signaling in keratinocytes. Hyper-proliferation of keratinocytes belongs to major clinical manifestations in psoriasis. To modulate IL-17-mediated inflammatory cascade, we generated a unique collection of IL-17RA-targeting protein binders that prevent from binding of human IL-17A cytokine to its cell-surface receptor. To this goal, we used a highly complex combinatorial library derived from scaffold of albumin-binding domain (ABD) of streptococcal protein G, and ribosome display selection, to yield a collection of ABD-derived high-affinity ligands of human IL-17RA, called ARS binders. From 67 analyzed ABD variants, 7 different sequence families were identified. Representatives of these groups competed with human IL-17A for binding to recombinant IL-17RA receptor as well as to IL-17RA-Immunoglobulin G chimera, as tested in enzyme-linked immunosorbent assay (ELISA). Five ARS variants bound to IL-17RA-expressing THP-1 cells and blocked binding of human IL-17 cytokine to the cell surface, as tested by flow cytometry. Three variants exhibited high-affinity binding with a nanomolar Kd value to human keratinocyte HaCaT cells, as measured using Ligand Tracer Green Line. Upon IL-17-stimulated activation, ARS variants inhibited secretion of Gro-α (CXCL1) by normal human skin fibroblasts in vitro. Thus, we identified a novel class of inhibitory ligands that might serve as immunosuppressive IL-17RA-targeted non-IgG protein antagonists.

scholarly journals A Targeted Catalytic Nanobody (T-CAN) with Asparaginolytic Activity

Cancers ◽  
2021 ◽  
Vol 13 (22) ◽  
pp. 5637
Author(s):  
Maristella Maggi ◽  
Greta Pessino ◽  
Isabella Guardamagna ◽  
Leonardo Lonati ◽  
Cristina Pulimeno ◽  
...  
Keyword(s):  
Lymphoblastic Leukemia ◽  
Cell Surface Receptor ◽  
Single Domain Antibody ◽  
Antibody Drug Conjugate ◽  
E Coli ◽  
Novel Approach ◽  
Innovative Solutions ◽  
Surface Receptor ◽  
New Type

E. coli L-asparaginase is an amidohydrolase (EC 3.5.1.1) which has been successfully used for the treatment of Acute Lymphoblastic Leukemia for over 50 years. Despite its efficacy, its side effects, and especially its intrinsic immunogenicity, hamper its usage in a significant subset of cases, thus limiting therapeutic options. Innovative solutions to improve on these drawbacks have been attempted, but none of them have been truly successful so far. In this work, we fully replaced the enzyme scaffold, generating an active, miniaturized form of L-asparaginase by protein engineering of a camel single domain antibody, a class of antibodies known to have a limited immunogenicity in humans. We then targeted it onto tumor cells by an antibody scFv fragment directed onto the CD19 B-cell surface receptor expressed on ALL cells. We named this new type of nanobody-based antibody-drug conjugate “Targeted Catalytic Nanobody” (T-CAN). The new molecule retains the catalytic activity and the binding capability of the original modules and successfully targets CD19 expressing cells in vitro. Thanks to its theoretically reduced immunogenic potential compared to the original molecule, the T-CAN can represent a novel approach to tackle current limitations in L-asparaginase usage.

scholarly journals Defective delivery of iron to the developing red cell of the Belgrade laboratory rat

Blood ◽  
1980 ◽  
Vol 55 (4) ◽  
pp. 645-648 ◽  
Author(s):  
JA Edwards ◽  
AL Sullivan ◽  
JE Hoke
Keyword(s):  
B Cells ◽  
Rat Plasma ◽  
Cell Surface Receptor ◽  
Erythroid Cell ◽  
Recessive Trait ◽  
Laboratory Rat ◽  
Surface Receptor ◽  
Normal Rat ◽  
And Control

Erythroid cell iron and transferrin uptake and release was studied in the anemia of the Belgrade laboratory rat (gene symbol, b), an autosomal recessive trait characterized by hypochromia and hyperferrinemia. When reticulocyte-rich red cells were incubated in vitro with doubly (59Fe, 125I) labeled transferrin, b/b cells demonstrated a significantly higher uptake of transferrin (164% of control at 60 min), and a significantly lower uptake of iron (21% of control at 60 min) than control cells. These findings with b/b cells were simulated by sodium-fluoride-treated control cells, but not by trypsin-treated control cells. When reticulocytes exposed to doubly labeled transferrin were incubated in normal rat plasma, there was a substantial loss of 125I from both the b/b cells (mean 71%) and control cells (mean 49%), but only a loss of 59Fe from the b/b cells (mean 21%). These findings suggest a defect in the delivery of iron to the b/b reticulocyte, which is distal to the binding of transferrin to its cell surface receptor.

scholarly journals The role of Neuropilin-1 in COVID-19

2021 ◽  
Vol 17 (1) ◽  
pp. e1009153
Author(s):  
Bindu S. Mayi ◽  
Jillian A. Leibowitz ◽  
Arden T. Woods ◽  
Katherine A. Ammon ◽  
Alphonse E. Liu ◽  
...  
Keyword(s):  
Immune Function ◽  
Viral Entry ◽  
Axonal Guidance ◽  
Cell Surface Receptor ◽  
Neuropilin 1 ◽  
Surface Receptor ◽  
The Central Nervous System

Neuropilin-1 (NRP-1), a member of a family of signaling proteins, was shown to serve as an entry factor and potentiate SARS Coronavirus 2 (SARS-CoV-2) infectivity in vitro. This cell surface receptor with its disseminated expression is important in angiogenesis, tumor progression, viral entry, axonal guidance, and immune function. NRP-1 is implicated in several aspects of a SARS-CoV-2 infection including possible spread through the olfactory bulb and into the central nervous system and increased NRP-1 RNA expression in lungs of severe Coronavirus Disease 2019 (COVID-19). Up-regulation of NRP-1 protein in diabetic kidney cells hint at its importance in a population at risk of severe COVID-19. Involvement of NRP-1 in immune function is compelling, given the role of an exaggerated immune response in disease severity and deaths due to COVID-19. NRP-1 has been suggested to be an immune checkpoint of T cell memory. It is unknown whether involvement and up-regulation of NRP-1 in COVID-19 may translate into disease outcome and long-term consequences, including possible immune dysfunction. It is prudent to further research NRP-1 and its possibility of serving as a therapeutic target in SARS-CoV-2 infections. We anticipate that widespread expression, abundance in the respiratory and olfactory epithelium, and the functionalities of NRP-1 factor into the multiple systemic effects of COVID-19 and challenges we face in management of disease and potential long-term sequelae.

scholarly journals gp96 Is a Human Colonocyte Plasma Membrane Binding Protein for Clostridium difficile Toxin A

2008 ◽  
Vol 76 (7) ◽  
pp. 2862-2871 ◽  
Author(s):  
Xi Na ◽  
Ho Kim ◽  
Mary P. Moyer ◽  
Charalabos Pothoulakis ◽  
J. Thomas LaMont
Keyword(s):  
Plasma Membrane ◽  
Clostridium Difficile ◽  
Binding Protein ◽  
Membrane Binding ◽  
Cell Surface Receptor ◽  
Toxin A ◽  
Surface Receptor ◽  
A Cell ◽  
Plasma Membrane Binding

ABSTRACT Clostridium difficile toxin A (TxA), a key mediator of antibiotic-associated colitis, requires binding to a cell surface receptor prior to internalization. Our aim was to identify novel plasma membrane TxA binding proteins on human colonocytes. TxA was coupled with biotin and cross-linked to the surface of HT29 human colonic epithelial cells. The main colonocyte binding protein for TxA was identified as glycoprotein 96 (gp96) by coimmunoprecipitation and mass spectrum analysis. gp96 is a member of the heat shock protein family, which is expressed on human colonocyte apical membranes as well as in the cytoplasm. TxA binding to gp96 was confirmed by fluorescence immunostaining and in vitro coimmunoprecipitation. Following TxA binding, the TxA-gp96 complex was translocated from the cell membrane to the cytoplasm. Pretreatment with gp96 antibody decreased TxA binding to colonocytes and inhibited TxA-induced cell rounding. Small interfering RNA directed against gp96 reduced gp96 expression and cytotoxicity in colonocytes. TxA-induced inflammatory signaling via p38 and apoptosis as measured by activation of BAK (Bcl-2 homologous antagonist/killer) and DNA fragmentation were decreased in gp96-deficient B cells. We conclude that human colonocyte gp96 serves as a plasma membrane binding protein that enhances cellular entry of TxA, participates in cellular signaling events in the inflammatory cascade, and facilitates cytotoxicity.

Thranbospondin Promotes Cell-and Platelet-Substratum Adhesion

1987 ◽  
Author(s):  
George P Tuszynski ◽  
Vicki L Rothman ◽  
Andrew Murphy ◽  
Katherine Siegler ◽  
Linda Smith ◽  
...  
Keyword(s):  
Cell Adhesion ◽  
Cell Surface ◽  
Polyacrylamide Gel Electrophoresis ◽  
Cell Types ◽  
Preliminary Evidence ◽  
Human Platelets ◽  
Cell Surface Receptor ◽  
Binding Assays ◽  
Surface Receptor

Thrombospondin (TSP), isolated from human platelets, promotes the in vitro, calcium-specific adhesion of a variety of cells, including platelets, melanoma cells, muscle cells, endothelial cells, fibroblasts, and epithelial cells. The cell adhesion-promoting activity of TSP is species independent since human, bovine, pig, rat and mouse cells all adhered to TSP. Furthermore, the cell adhesion-promoting activity of TSP is specific and not due to a nonspecific protein effect or to contamination by fibronectin, vitronectin, or laminin. That is, neither bovine serum albumin nor TSP preparations treated with a monospecific anti-TSP antibody support cell adhesion. As analyzed by polyacrylamide-gel electrophoresis and specific antibody binding assays, the TSP preparations used in these studies contained no detectable fibronectin or laminin and less than 0.04% vitronectin. The cell surface receptor for TSP appears distinct frcm that of fibronectin since an antiserum that blocks cell adhesion to fibronectin has no effect on adhesion to TSP. In addition, The platelet cell surface receptor for TSP appears distinct, frcm that of fibrinogen since thrcmbasthenic platelets adhere to TSP as well as control platelets. Antibodies to the GPIIb-GPIIIa complex block platelet adhesion to fibrinogen but have no effect on adhesion to TSP. Initial characterization of the cell surface receptor for TSP shows it to be protein in nature since cells treated with trypsin fail to adhere to TSP. In summary, our results provide the first clear evidence that TSP specifically promotes cell-substratum adhesion of a variety of cell types independent of the animal species. Our preliminary evidence suggests that the cell-surface receptor(s) for TSP is protein and that it is distinct for the receptor for fibronectin and fibrinogen. Our data suggest that TSP may play a central role in normal adhesive events mediated by platelets and other cells, such as those involved in hemostasis and wound healing. In addition, TSP may be involved in pathological adhesive events mediated by platelets and tumor cells, such as those involved in cardiovascular disease and tumor cell metastasis.

Two Signaling Pathways Can Increase Fas Expression in Human Thymocytes

Blood ◽  
1998 ◽  
Vol 92 (4) ◽  
pp. 1297-1307 ◽  
Author(s):  
Nathalie Moulian ◽  
Jocelyne Bidault ◽  
Claude Planché ◽  
Sonia Berrih-Aknin
Keyword(s):  
Signaling Pathways ◽  
Antigen Expression ◽  
Interferon Γ ◽  
Cell Surface Receptor ◽  
Metabolic Inhibitor ◽  
Interleukin 7 ◽  
Cytokine Activation ◽  
Surface Receptor ◽  
Induced Apoptosis

Fas, a cell surface receptor, can induce apoptosis after cross-linking with its ligand. Fewer than 3% of human thymocytes strongly express Fas. We report that Fas antigen expression can be upregulated by two signaling pathways in vitro, one mediated by anti-CD3 and the other by interleukin-7 + interferon-γ. The two signaling pathways differed in several respects. (1) Fas expression increased in all thymic subsets after cytokine activation, but only in the CD4 lineage after anti-CD3 activation. (2) Fas upregulation was inhibited by cyclosporin A (a calcineurin inhibitor) in anti-CD3–activated but not in cytokine-activated thymocytes. (3) Cycloheximide (a metabolic inhibitor) inhibited Fas upregulation in cytokine-activated thymocytes but not in anti-CD3–activated thymocytes. (4) Cytokine-activated thymocytes were more susceptible than anti-CD3–activated thymocytes to Fas-induced apoptosis, a difference mainly accounted for by CD4+ cells. The nature of the stimulus might thus influence the susceptibility of human thymocytes to Fas-induced apoptosis. © 1998 by The American Society of Hematology.

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