scholarly journals Leptospiral Endostatin-Like Protein A Is a Bacterial Cell Surface Receptor for Human Plasminogen

2010 ◽  
Vol 78 (5) ◽  
pp. 2053-2059 ◽  
Author(s):  
Ashutosh Verma ◽  
Catherine A. Brissette ◽  
Amy A. Bowman ◽  
Samir T. Shah ◽  
Peter F. Zipfel ◽  
...  
Keyword(s):  
Binding Sites ◽  
Protein A ◽  
Aminocaproic Acid ◽  
Factor H ◽  
Cell Surface Receptor ◽  
Dependent Manner ◽  
Public Health Importance ◽  
Amino Terminal ◽  
Surface Receptor ◽  
Human Plasminogen

ABSTRACT The spirochete Leptospira interrogans is a highly invasive pathogen of worldwide public health importance. Studies from our laboratories and another have demonstrated that L. interrogans can acquire host plasminogen on its surface. Exogenous plasminogen activators can then convert bound plasminogen into the functionally active protease plasmin. In this study, we extend upon those observations and report that leptospiral endostatin-like protein A (LenA) binds human plasminogen in a dose-dependent manner. LenA-plasminogen interactions were significantly inhibited by the lysine analog ξ-aminocaproic acid, suggesting that the lysine-binding sites on the amino-terminal kringle portion of the plasminogen molecule play a role in the binding. Previous studies have shown that LenA also binds complement regulator factor H and the extracellular matrix component laminin. Plasminogen competed with both factor H and laminin for binding to LenA, which suggests overlapping ligand-binding sites on the bacterial receptor. Finally, LenA-bound plasminogen could be converted to plasmin, which in turn degraded fibrinogen, suggesting that acquisition of host-derived plasmin by LenA may aid bacterial dissemination throughout host tissues.

scholarly journals Dectin-1-Mediated Production of Pro-Inflammatory Cytokines Induced by Yeast β-Glucans in Bovine Monocytes

2021 ◽  
Vol 12 ◽  
Author(s):  
Ana R. V. Pedro ◽  
Tânia Lima ◽  
Ricardo Fróis-Martins ◽  
Bárbara Leal ◽  
Isabel C. Ramos ◽  
...  
Keyword(s):  
Gene Expression ◽  
Cell Surface ◽  
Inflammatory Cytokines ◽  
Surface Expression ◽  
Cell Surface Receptor ◽  
Dependent Manner ◽  
Feed Supplements ◽  
Surface Receptor ◽  
Dose Dependent ◽  
Pro Inflammatory Cytokines

Yeast-derived products containing β-glucans have long been used as feed supplements in domesticated animals in an attempt to increase immunity. β-glucans are mainly recognized by the cell surface receptor CLEC7A, also designated Dectin-1. Although the immune mechanisms elicited through Dectin-1 activation have been studied in detail in mice and humans, they are poorly understood in other species. Here, we evaluated the response of bovine monocytes to soluble and particulate purified β-glucans, and also to Zymosan. Our results show that particulate, but not soluble β-glucans, can upregulate the surface expression of costimulatory molecules CD80 and CD86 on bovine monocytes. In addition, stimulated cells increased production of IL-8 and of TNF, IL1B, and IL6 mRNA expression, in a dose-dependent manner, which correlated positively with CLEC7A gene expression. Production of IL-8 and TNF expression decreased significantly after CLEC7A knockdown using two different pairs of siRNAs. Overall, we demonstrated here that bovine monocytes respond to particulate β-glucans, through Dectin-1, by increasing the expression of pro-inflammatory cytokines. Our data support further studies in cattle on the induction of trained immunity using dietary β-glucans.

scholarly journals Designing multivalent probes for tunable superselective targeting

2015 ◽  
Vol 112 (18) ◽  
pp. 5579-5584 ◽  
Author(s):  
Galina V. Dubacheva ◽  
Tine Curk ◽  
Rachel Auzély-Velty ◽  
Daan Frenkel ◽  
Ralf P. Richter
Keyword(s):  
Binding Sites ◽  
Rational Design ◽  
Cell Surface Receptor ◽  
Molecular Characteristics ◽  
Surface Binding ◽  
Binding Properties ◽  
Practical Applications ◽  
Mechanistic Insight ◽  
Surface Receptor ◽  
Insight Into

Specific targeting is common in biology and is a key challenge in nanomedicine. It was recently demonstrated that multivalent probes can selectively target surfaces with a defined density of surface binding sites. Here we show, using a combination of experiments and simulations on multivalent polymers, that such “superselective” binding can be tuned through the design of the multivalent probe, to target a desired density of binding sites. We develop an analytical model that provides simple yet quantitative predictions to tune the polymer’s superselective binding properties by its molecular characteristics such as size, valency, and affinity. This work opens up a route toward the rational design of multivalent probes with defined superselective targeting properties for practical applications, and provides mechanistic insight into the regulation of multivalent interactions in biology. To illustrate this, we show how the superselective targeting of the extracellular matrix polysaccharide hyaluronan to its main cell surface receptor CD44 is controlled by the affinity of individual CD44–hyaluronan interactions.

scholarly journals Borrelia burgdorferi Infection-Associated Surface Proteins ErpP, ErpA, and ErpC Bind Human Plasminogen

2008 ◽  
Vol 77 (1) ◽  
pp. 300-306 ◽  
Author(s):  
Catherine A. Brissette ◽  
Katrin Haupt ◽  
Diana Barthel ◽  
Anne E. Cooley ◽  
Amy Bowman ◽  
...  
Keyword(s):  
Borrelia Burgdorferi ◽  
Critical Role ◽  
Aminocaproic Acid ◽  
Factor H ◽  
Surface Proteins ◽  
Primary Role ◽  
Dependent Manner ◽  
Lysine Residues ◽  
Complement Regulator ◽  
Mammalian Infection

ABSTRACT Host-derived plasmin plays a critical role in mammalian infection by Borrelia burgdorferi. The Lyme disease spirochete expresses several plasminogen-binding proteins. Bound plasminogen is converted to the serine protease plasmin and thereby may facilitate the bacterium's dissemination throughout the host by degrading extracellular matrix. In this work, we demonstrate plasminogen binding by three highly similar borrelial outer surface proteins, ErpP, ErpA, and ErpC, all of which are expressed during mammalian infection. Extensive characterization of ErpP demonstrated that this protein bound in a dose-dependent manner to lysine binding site I of plasminogen. Removal of three lysine residues from the carboxy terminus of ErpP significantly reduced binding of plasminogen, and the presence of a lysine analog, ε-aminocaproic acid, inhibited the ErpP-plasminogen interaction, thus strongly pointing to a primary role for lysine residues in plasminogen binding. Ionic interactions are not required in ErpP binding of plasminogen, as addition of excess NaCl or the polyanion heparin did not have any significant effect on binding. Plasminogen bound to ErpP could be converted to the active enzyme, plasmin. The three plasminogen-binding Erp proteins can also bind the host complement regulator factor H. Plasminogen and factor H bound simultaneously and did not compete for binding to ErpP, indicating separate binding sites for both host ligands and the ability of the borrelial surface proteins to bind both host proteins.

scholarly journals SUN-LB130 Identification of IGSF1 Ligands

2020 ◽  
Vol 4 (Supplement_1) ◽  
Author(s):  
Courtney L Smith ◽  
Andrew N Bayne ◽  
Jean-François Trempe ◽  
Daniel J Bernard
Keyword(s):  
Cell Surface ◽  
Transmembrane Domain ◽  
Protein Complexes ◽  
Protein A ◽  
Negative Control ◽  
Cell Surface Receptor ◽  
Immunoglobulin Superfamily ◽  
Central Hypothyroidism ◽  
Surface Receptors ◽  
Surface Receptor

Abstract Immunoglobulin superfamily, member 1 (IGSF1), is an X-linked, type 1 transmembrane glycoprotein that is highly expressed in the anterior pituitary gland and testes. Mutations in the IGSF1 gene cause congenital central hypothyroidism, variable hypoprolactinemia, growth hormone dysregulation, and macroorchidism. Igsf1 knockout mice exhibit reduced pituitary TRH receptor (Trhr1) expression with an associated impairment in TRH-stimulated TSH secretion. The mechanism through which IGSF1 loss leads to reductions in Trhr1 levels is unresolved, at least in part because IGSF1’s cellular functions are unknown. The mature form of the IGSF1 protein consists of seven extracellular Ig loops, a single transmembrane domain containing a positively charged arginine, and a short intracellular carboxy-tail devoid of known functional motifs. Recently, IGSF1 was argued to be a member of the leukocyte receptor cluster (LRC) family. LRC proteins act as cell surface receptors for soluble or membrane-bound proteins. We therefore hypothesized that IGSF1 is a cell surface receptor for a presently undescribed ligand that regulates Trhr1 expression in pituitary thyrotrope cells. To identify candidate IGSF1 ligands, we implemented a new ligand trapping method, Ecto-Fc MS. We fused the extracellular (Ecto) domain of IGSF1 to the fragment crystallizable (Fc) region of human IgG, creating an Ecto-Fc fusion protein. Secreted IGSF1-Fc was purified and used as a ligand trap for bait proteins extracted from rat testes. The protein complexes were affinity purified with protein A beads, trypsin digested into peptides, subjected to orthogonal high-pH fractionation, and identified by tandem LC-MS/MS. More than 700 proteins were enriched in IGSF1-Fc preparations compared to an Fc-only negative control. Several secreted ligands and plasma-membrane proteins were identified, many of which are also expressed in pituitary thyrotrope cells. Identifying the ligand or ligands will enable us to determine IGSF1 function, and may lead to the discovery of novel causes of central hypothyroidism and macroorchidism.

scholarly journals Effectiveness of a Controlled 5-FU Delivery Based on FZD10 Antibody-Conjugated Liposomes in Colorectal Cancer In vitro Models

Pharmaceutics ◽  
2020 ◽  
Vol 12 (7) ◽  
pp. 650
Author(s):  
Maria Principia Scavo ◽  
Annalisa Cutrignelli ◽  
Nicoletta Depalo ◽  
Elisabetta Fanizza ◽  
Valentino Laquintana ◽  
...  
Keyword(s):  
Colorectal Cancer ◽  
Protein A ◽  
Scratch Test ◽  
In Vitro Models ◽  
Cell Surface Receptor ◽  
Test Field ◽  
Selective Treatment ◽  
Surface Receptor ◽  
Electron Microscopes

The use of controlled delivery therapy in colorectal cancer (CRC) reduces toxicity and side effects. Recently, we have suggested that the Frizzled 10 (FZD10) protein, a cell surface receptor belonging to the FZD protein family that is overexpressed in CRC cells, is a novel candidate for targeting and treatment of CRC. Here, the anticancer effect of novel immuno-liposomes loaded with 5-Fluorouracil (5-FU), decorated with an antibody against FZD10 (anti-FZD10/5-FU/LPs), was evaluated in vitro on two different CRC cell lines, namely metastatic CoLo-205 and nonmetastatic CaCo-2 cells, that were found to overexpress FZD10. The anti-FZD10/5-FU/LPs obtained were extensively characterized and their preclinical therapeutic efficacy was evaluated with the MTS cell proliferation assay based on reduction of tetrazolium compound, scratch test, Field Emission Scanning Electron Microscopes (FE-SEM) investigation and immunofluorescence analysis. The results highlighted that the cytotoxic activity of 5-FU was enhanced when encapsulated in the anti-FZD10 /5-FU/LPs at the lowest tested concentrations, as compared to the free 5-FU counterparts. The immuno-liposomes proposed herein possess a great potential for selective treatment of CRC because, in future clinical applications, they can be encapsulated in gastro-resistant capsules or suppositories for oral or rectal delivery, thereby successfully reaching the intestinal tract in a minimally invasive manner.

Urokinase induces its own expression in Beas2B lung epithelial cells

2002 ◽  
Vol 283 (2) ◽  
pp. L319-L328 ◽  
Author(s):  
Sreerama Shetty ◽  
Usha R. Pendurthi ◽  
Prathap Kumar Shetty Halady ◽  
Ali O. Azghani ◽  
Steven Idell
Keyword(s):  
Epithelial Cells ◽  
Tyrosine Kinase ◽  
Lung Inflammation ◽  
Cellular Proliferation ◽  
Kinase Inhibitor ◽  
Lung Epithelial Cells ◽  
Cell Surface Receptor ◽  
Dependent Manner ◽  
Amino Terminal ◽  
Lung Epithelial

The urokinase-type plasminogen activator (uPA) interacts with its receptor (uPAR) to promote local proteolysis as well as cellular proliferation and migration. These functions contribute to the pathogenesis of lung inflammation and remodeling as well as the growth and invasiveness of lung neoplasms. In this study, we sought to determine if uPA alters its own expression in lung epithelial cells. Using immunoprecipitation and Western and Northern blotting techniques, we found that uPA treatment enhanced uPA expression in Beas2B lung epithelial cells in a time- and concentration-dependent manner. The induction of uPA expression is mediated through its cell surface receptor uPAR and does not require uPA enzymatic activity. The amino-terminal fragment of uPA, lacking the catalytic domain, is sufficient to induce uPA expression. The serine protease plasmin and the protease inhibitor aprotinin failed to alter uPA-mediated uPA expression, whereas α-thrombin potentiated the response. Pretreatment of Beas2B cells with a tyrosine kinase inhibitor, herbimycin, suggests that activation of tyrosine kinase(s) is involved in the uPA-mediated uPA expression. Induction of uPA expression by exposure of lung-derived epithelial cells to uPA is a newly defined pathway by which this protease could influence expression of local fibrinolytic activity and other uPA-dependent cellular responses germane to lung inflammation or neoplasia.

Regulation of c-ret expression by retinoic acid in rat metanephros: implication in nephron mass control

1998 ◽  
Vol 275 (6) ◽  
pp. F938-F945 ◽  
Author(s):  
Evelyne Moreau ◽  
José Vilar ◽  
Martine Lelièvre-Pégorier ◽  
Claudie Merlet-Bénichou ◽  
Thierry Gilbert
Keyword(s):  
Retinoic Acid ◽  
Molecular Mechanisms ◽  
Kidney Development ◽  
Mrna Level ◽  
Cell Surface Receptor ◽  
Dependent Manner ◽  
All Trans Retinoic Acid ◽  
Surface Receptor ◽  
Dose Dependent

Vitamin A and its derivatives have been shown to promote kidney development in vitro in a dose-dependent fashion. To address the molecular mechanisms by which all- trans-retinoic acid (RA) may regulate the nephron mass, rat kidneys were removed on embryonic day 14( E14) and grown in organ culture under standard or RA-stimulated conditions. By using RT-PCR, we studied the expression of the glial cell line-derived neurotrophic factor (GDNF), its cell surface receptor-α (GDNFR-α), and the receptor tyrosine kinase c-ret, known to play a major role in renal organogenesis. Expression of GDNF and GDNFR-α transcripts was high at the time of explantation and remained unaffected in culture with or without RA. In contrast, c-ret mRNA level, which was low in E14 metanephros and dropped rapidly in vitro, was increased by RA in a dose-dependent manner. The same is true at the protein level. Exogenous GDNF barely promotes additional nephron formation in vitro. Thus the present data establish c-ret as a key target of retinoids during kidney organogenesis.

scholarly journals Combined QM/MM Study of Thyroid and Steroid Hormone Analogue Interactions with Integrin

2012 ◽  
Vol 2012 ◽  
pp. 1-12 ◽  
Author(s):  
Marek Freindorf ◽  
Thomas R. Furlani ◽  
Jing Kong ◽  
Vivian Cody ◽  
Faith B. Davis ◽  
...  
Keyword(s):  
Binding Sites ◽  
Cyclic Peptide ◽  
Binding Pocket ◽  
Biological Data ◽  
Cell Surface Receptor ◽  
Side Chain ◽  
Αvβ3 Integrin ◽  
Binding Modes ◽  
Surface Receptor ◽  
A Cell

Recent biochemical studies have identified a cell surface receptor for thyroid and steroid hormones that bind near the arginine-glycine-aspartate (RGD) recognition site on the heterodimeric αvβ3 integrin. To further characterize the intermolecular interactions for a series of hormone analogues, combined quantum mechanical and molecular mechanical (QM/MM) methods were used to calculate their interaction energies. All calculations were performed in the presence of either calcium (Ca2+) or magnesium (Mg2+) ions. These data reveal that 3,5′-triiodothyronine (T3) and 3,5,3′,5′-tetraiodothyroacetic acid (T4ac) bound in two different modes, occupying two alternate sites, one of which is along the Arg side chain of the RGD cyclic peptide site. These orientations differ from those of the other ligands whose alternate binding modes placed the ligands deeper within the RGD binding pocket. These observations are consistent with biological data that indicate the presence of two discrete binding sites that control distinct downstream signal transduction pathways for T3.

scholarly journals Symbiotic root infections in Medicago truncatula require remorin-mediated receptor stabilization in membrane nanodomains

2018 ◽  
Vol 115 (20) ◽  
pp. 5289-5294 ◽  
Author(s):  
Pengbo Liang ◽  
Thomas F. Stratil ◽  
Claudia Popp ◽  
Macarena Marín ◽  
Jessica Folgmann ◽  
...  
Keyword(s):  
Host Cell ◽  
Medicago Truncatula ◽  
Molecular Mechanisms ◽  
Cell Surface Receptor ◽  
Dependent Manner ◽  
Cell Infection ◽  
Molecular Scaffold ◽  
Rhizobial Inoculation ◽  
Surface Receptor ◽  
Functional Relevance

Plant cell infection is tightly controlled by cell surface receptor-like kinases (RLKs). Like other RLKs, the Medicago truncatula entry receptor LYK3 laterally segregates into membrane nanodomains in a stimulus-dependent manner. Although nanodomain localization arises as a generic feature of plant membrane proteins, the molecular mechanisms underlying such dynamic transitions and their functional relevance have remained poorly understood. Here we demonstrate that actin and the flotillin protein FLOT4 form the primary and indispensable core of a specific nanodomain. Infection-dependent induction of the remorin protein and secondary molecular scaffold SYMREM1 results in subsequent recruitment of ligand-activated LYK3 and its stabilization within these membrane subcompartments. Reciprocally, the majority of this LYK3 receptor pool is destabilized at the plasma membrane and undergoes rapid endocytosis in symrem1 mutants on rhizobial inoculation, resulting in premature abortion of host cell infections. These data reveal that receptor recruitment into nanodomains is indispensable for their function during host cell infection.

scholarly journals Bifidobacterial enolase, a cell surface receptor for human plasminogen involved in the interaction with the host

Microbiology ◽  
2009 ◽  
Vol 155 (10) ◽  
pp. 3294-3303 ◽  
Author(s):  
Marco Candela ◽  
Elena Biagi ◽  
Manuela Centanni ◽  
Silvia Turroni ◽  
Manuela Vici ◽  
...  
Keyword(s):  
Cell Surface ◽  
Glycolytic Enzyme ◽  
Site Directed Mutagenesis ◽  
Cell Surface Receptor ◽  
Surface Receptor ◽  
A Cell ◽  
Human Plasminogen ◽  
Equilibrium Dissociation ◽  
Nanomolar Range ◽  
Positively Charged

The interaction with the host plasminogen/plasmin system represents a novel component in the molecular cross-talk between bifidobacteria and human host. Here, we demonstrated that the plasminogen-binding bifidobacterial species B. longum, B. bifidum, B. breve and B. lactis share the key glycolytic enzyme enolase as a surface receptor for human plasminogen. Enolase was visualized on the cell surface of the model strain B. lactis BI07. The His-tagged recombinant protein showed a high affinity for human plasminogen, with an equilibrium dissociation constant in the nanomolar range. By site-directed mutagenesis we demonstrated that the interaction between the B. lactis BI07 enolase and human plasminogen involves an internal plasminogen-binding site homologous to that of pneumococcal enolase. According to our data, the positively charged residues Lys-251 and Lys-255, as well as the negatively charged Glu-252, of the B. lactis BI07 enolase are crucial for plasminogen binding. Acting as a human plasminogen receptor, the bifidobacterial surface enolase is suggested to play an important role in the interaction process with the host.

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