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The Prostate Jul 2000Galectin-3 is a carbohydrate-binding protein whose level of expression has been shown to be correlated with metastatic potential in a number of different tumor types....
BACKGROUND
Galectin-3 is a carbohydrate-binding protein whose level of expression has been shown to be correlated with metastatic potential in a number of different tumor types. The purpose of this investigation was to examine galectin-3 expression in several tumorigenic and nontumorigenic prostate cell lines and prostate tissue samples.
METHODS
The expression of galectin-3 in cell lines and tissue samples was evaluated by tissue immunohistochemistry and Western blot analysis.
RESULTS
Human cell lines PC-3M, PC-3, DU-145, PrEC-1, and MCF10A demonstrated the presence of galectin-3. Galectin-3 was not detected in TSU-pr1 and LNCaP by Western blot analysis. We furthered our studies by examining a series of human prostate tissue samples for expression of galectin-3. Overall, approximately 60-70% of the normal tissue examined demonstrated heterogenous expression of galectin-3. In stage II tumors, however, there was a dramatic decrease in galectin-3 expression in both PIN and tumor sections, with only 10.5% (2/19) of these samples expressing this protein. Stage III tumors also demonstrated a decreased expression of galectin-3, although this downregulation was not as dramatic, with 35% of PIN samples and 52% of tumor tissue expressing galectin-3 (P < 0.01).
CONCLUSIONS
These data demonstrate that galectin-3 is downregulated in prostate cancer. The altered downregulation pattern of galectin-3 observed between tumor stages suggests different roles for galectin-3 in the progression of prostate cancer.
Topics: Antigens, Differentiation; Blotting, Western; Cell Line; Galectin 3; Gene Expression Regulation, Neoplastic; Humans; Immunohistochemistry; Male; Prostate; Prostatic Neoplasms; Tumor Cells, Cultured
PubMed: 10881021
DOI: 10.1002/1097-0045(20000701)44:2<118::aid-pros4>3.0.co;2-u -
Scientific Reports Sep 2018The oncogenic gammaherpesviruses, Epstein-Barr virus (EBV) and Kaposi's sarcoma herpesvirus (KSHV), are etiologically associated with a variety of human cancers,...
The oncogenic gammaherpesviruses, Epstein-Barr virus (EBV) and Kaposi's sarcoma herpesvirus (KSHV), are etiologically associated with a variety of human cancers, including Burkitt's lymphoma (BL), Hodgkin lymphoma (HL), Kaposi's sarcoma (KS), and primary effusion lymphoma (PEL). Recently, we demonstrated KSHV infection of B- and endothelial cells to significantly upregulate the expression of interferon induced transmembrane protein 1 (IFITM1) which in turn enhances virus entry. This is an extension of the above study. In here, we determined EBV infection of cells to trigger IFITM1 expression, in vitro. Silencing IFITM1 expression using siRNA specifically lowered gammaherpesvirus infection of cells at a post binding stage of entry. A natural model system to explore the effect of IFITM1 on gammaherpesvirus infection in vivo is infection of BALB/c mice with murine gammaherpesvirus 68 (MHV-68). Priming mice with siRNA specific to IFITM1 significantly lowered MHV-68 titers in the lung specimens compared to priming with (NS)siRNA or PBS. MHV-68 titers were monitored by plaque assay and qPCR. Taken together, for the first time, this study provides insight into the critical role of IFITM1 to promoting in vivo gammaherpesvirus infections.
Topics: Animals; Antigens, Differentiation; Cell Line, Tumor; Gammaherpesvirinae; Herpesviridae Infections; Humans; Lung; Mice; Virus Latency; Virus Replication
PubMed: 30237526
DOI: 10.1038/s41598-018-32350-0 -
Proceedings of the National Academy of... Jul 2016Siglec-8 is a human immune-inhibitory receptor that, when engaged by specific self-glycans, triggers eosinophil apoptosis and inhibits mast cell degranulation, providing...
Siglec-8 is a human immune-inhibitory receptor that, when engaged by specific self-glycans, triggers eosinophil apoptosis and inhibits mast cell degranulation, providing an endogenous mechanism to down-regulate immune responses of these central inflammatory effector cells. Here we used solution NMR spectroscopy to dissect the fine specificity of Siglec-8 toward different sialylated and sulfated carbohydrate ligands and determined the structure of the Siglec-8 lectin domain in complex with its prime glycan target 6'-sulfo sialyl Lewis(x) A canonical motif for sialic acid recognition, extended by a secondary motif formed by unique loop regions, recognizing 6-O-sulfated galactose dictates tight specificity distinct from other Siglec family members and any other endogenous glycan recognition receptors. Structure-guided mutagenesis revealed key contacts of both interfaces to be equally essential for binding. Our work provides critical structural and mechanistic insights into how Siglec-8 selectively recognizes its glycan target, rationalizes the functional impact of site-specific glycan sulfation in modulating this lectin-glycan interaction, and will enable the rational design of Siglec-8-targeted agonists to treat eosinophil- and mast cell-related allergic and inflammatory diseases, such as asthma.
Topics: Antigens, CD; Antigens, Differentiation, B-Lymphocyte; Humans; Lectins; Models, Molecular; Mutagenesis, Site-Directed; Nuclear Magnetic Resonance, Biomolecular; Polysaccharides; Protein Domains
PubMed: 27357658
DOI: 10.1073/pnas.1602214113 -
Proceedings of the National Academy of... Jan 2019Natural killer (NK) cells are important component of innate immunity and also contribute to activating and reshaping the adaptive immune responses. The functions of NK...
Natural killer (NK) cells are important component of innate immunity and also contribute to activating and reshaping the adaptive immune responses. The functions of NK cells are modulated by multiple inhibitory and stimulatory receptors. Among these receptors, the activating receptor CD226 (DNAM-1) mediates NK cell activation via binding to its nectin-like (Necl) family ligand, CD155 (Necl-5). Here, we present a unique side-by-side arrangement pattern of two tandem immunoglobulin V-set (IgV) domains deriving from the ectodomains of both human CD226 (hCD226-ecto) and mouse CD226 (mCD226-ecto), which is substantially different from the conventional head-to-tail arrangement of other multiple Ig-like domain molecules. The hybrid complex structure of mCD226-ecto binding to the first domain of human CD155 (hCD155-D1) reveals a conserved binding interface with the first domain of CD226 (D1), whereas the second domain of CD226 (D2) both provides structural supports for the unique architecture of CD226 and forms direct interactions with CD155. In the absence of the D2 domain, CD226-D1 exhibited substantially reduced binding efficacy to CD155. Collectively, these findings would broaden our knowledge of the interaction between NK cell receptors and the nectin/Necl family ligands, as well as provide molecular basis for the development of CD226-targeted antitumor immunotherapeutics.
Topics: Animals; Antigens, Differentiation, T-Lymphocyte; Crystallography, X-Ray; Humans; Ligands; Mice; Protein Binding; Protein Domains; Protein Structure, Quaternary; Receptors, Virus
PubMed: 30591568
DOI: 10.1073/pnas.1815716116 -
Immunology Oct 2018CD6 is a type I T-cell surface receptor that modulates antigen receptor signalling. Its activity is regulated by binding of its membrane proximal domain (domain 3) to a...
CD6 is a type I T-cell surface receptor that modulates antigen receptor signalling. Its activity is regulated by binding of its membrane proximal domain (domain 3) to a cell surface ligand, CD166. CD6 monoclonal antibodies (mAbs) specific for the membrane distal domain (domain 1) perturb CD6 function including itolizumab (Alzumab™), which has reached the clinic for treatment of autoimmune disease. We characterized molecular and functional properties of several CD6 mAbs including itolizumab to define potential mechanisms of action. Epitope mapping using the crystal structure of CD6 to design mutants identified two distinct binding sites on different faces of domain 1, one containing residue R77, crucial for MT605 and T12.1 binding and the other, E63, which is crucial for itolizumab and MEM98. Analysis of binding kinetics revealed that itolizumab has a lower affinity compared with other CD6 domain 1 mAbs. We compared potential agonistic (triggering) and antagonistic (blocking) properties of CD6 mAbs in assays where the mechanism of action was well defined. CD6 domain 1 and 3 mAbs were equally effective in triggering interleukin-2 production by a cell line expressing a chimeric antigen receptor containing the extracellular region of CD6. CD6 domain 1 mAbs hindered binding of multivalent immobilized CD166 but were inferior compared with blocking by soluble CD166 or a CD6 domain 3 mAb. Characterization of CD6 mAbs provides an insight into how their functional effects in vivo may be interpreted and their therapeutic use optimized.
Topics: Animals; Antibodies, Monoclonal; Antibody Specificity; Antigens, CD; Antigens, Differentiation, T-Lymphocyte; Cell Line, Tumor; Epitopes; Humans; Mice; Models, Molecular; Mutagenesis; Mutation; Protein Conformation; Protein Domains; Protein Interaction Domains and Motifs; Rats; Signal Transduction
PubMed: 29772075
DOI: 10.1111/imm.12952 -
Cell Communication and Signaling : CCS May 2024T-cell membrane scaffold proteins are pivotal in T cell function, acting as versatile signaling hubs. While CD6 forms a large intracellular signalosome, it is...
BACKGROUND
T-cell membrane scaffold proteins are pivotal in T cell function, acting as versatile signaling hubs. While CD6 forms a large intracellular signalosome, it is distinguished from typical scaffolds like LAT or PAG by possessing a substantial ectodomain that binds CD166, a well-characterized ligand expressed on most antigen-presenting cells (APC), through the third domain (d3) of the extracellular region. Although the intact form of CD6 is the most abundant in T cells, an isoform lacking d3 (CD6∆d3) is transiently expressed on activated T cells. Still, the precise character of the signaling transduced by CD6, whether costimulatory or inhibitory, and the influence of its ectodomain on these activities are unclear.
METHODS
We expressed CD6 variants with extracellular deletions or cytosolic mutations in Jurkat cells containing eGFP reporters for NF-κB and NF-AT transcription factor activation. Cell activation was assessed by eGFP flow cytometry following Jurkat cell engagement with superantigen-presenting Raji cells. Using imaging flow cytometry, we evaluated the impact of the CD6-CD166 pair on cell adhesiveness during the antigen-dependent and -independent priming of T cells. We also examined the role of extracellular or cytosolic sequences on CD6 translocation to the immunological synapse, using immunofluorescence-based imaging.
RESULTS
Our investigation dissecting the functions of the extracellular and cytosolic regions of CD6 revealed that CD6 was trafficked to the immunological synapse and exerted tonic inhibition wholly dependent on its cytosolic tail. Surprisingly, however, translocation to the synapse occurred independently of the extracellular d3 and of engagement to CD166. On the other hand, CD6 binding to CD166 significantly increased T cell:APC adhesion. However, this activity was most evident in the absence of APC priming with superantigen, and thus, in the absence of TCR engagement.
CONCLUSIONS
Our study identifies CD6 as a novel 'on/off' scaffold-receptor capable of modulating responsiveness in two ways. Firstly, and independently of ligand binding, it establishes signaling thresholds through tonic inhibition, functioning as a membrane-bound scaffold. Secondly, CD6 has the capacity for alternative splicing-dependent variable ligand engagement, modulating its checkpoint-like activity.
Topics: Humans; Jurkat Cells; Signal Transduction; Antigens, CD; T-Lymphocytes; Antigens, Differentiation, T-Lymphocyte; Ligands; Lymphocyte Activation; Protein Binding; Cell Adhesion
PubMed: 38790044
DOI: 10.1186/s12964-024-01658-y -
Nihon Rinsho Men'eki Gakkai Kaishi =... Oct 2004Memory B cells, which carry immunoglobulin somatic hypermutations, generate immunoglobulins rapidly and vigorously in the secondary immune response. We recently... (Review)
Review
Memory B cells, which carry immunoglobulin somatic hypermutations, generate immunoglobulins rapidly and vigorously in the secondary immune response. We recently highlighted studies confirming that CD27 surface antigen is a memory B-cell marker. By using the memory B-cell marker, peripheral blood B cells were clearly distinguished into naive and memory B cells. The B cells are further separated to three populations by the expressions of CD27 and IgD: IgD+CD27- naive B cells (circulating B cell 1: cB1), IgD+CD27+ unclass-switched memory B cells (cB2, so-called IgM memory B cells) and IgD-CD27+ class-switched memory B cells (cB3, switched memory B cells). Here we show molecules which are involved in characteristics of naive/memory B cells and their functions. This functionally distinct B cell subset and molecules involved in the subset may represent an important mechanism by which quiescent human B cells can initiate and propagate rapid and vigorous immune memory responses, and regulate the synthesis of low/high affinity antibodies.
Topics: Antigens, CD; Antigens, Differentiation, B-Lymphocyte; B-Lymphocyte Subsets; Humans; Immunoglobulin D; Immunologic Memory; Tumor Necrosis Factor Receptor Superfamily, Member 7
PubMed: 15559319
DOI: 10.2177/jsci.27.309 -
Molecules (Basel, Switzerland) Feb 2015The C-type lectin-like receptors include the Nkrp1 protein family that regulates the activity of natural killer (NK) cells. Rat Nkrp1a was reported to bind...
The C-type lectin-like receptors include the Nkrp1 protein family that regulates the activity of natural killer (NK) cells. Rat Nkrp1a was reported to bind monosaccharide moieties in a Ca2+-dependent manner in preference order of GalNac > GlcNAc >> Fuc >> Gal > Man. These findings established for rat Nkrp1a have been extrapolated to all additional Nkrp1 receptors and have been supported by numerous studies over the past two decades. However, since 1996 there has been controversy and another article showed lack of interactions with saccharides in 1999. Nevertheless, several high affinity saccharide ligands were synthesized in order to utilize their potential in antitumor therapy. Subsequently, protein ligands were introduced as specific binders for Nkrp1 proteins and three dimensional models of receptor/protein ligand interaction were derived from crystallographic data. Finally, for at least some members of the NK cell C-type lectin-like proteins, the "sweet story" was impaired by two reports in recent years. It has been shown that the rat Nkrp1a and CD69 do not bind saccharide ligands such as GlcNAc, GalNAc, chitotetraose and saccharide derivatives (GlcNAc-PAMAM) do not directly and specifically influence cytotoxic activity of NK cells as it was previously described.
Topics: Animals; Antigens, CD; Antigens, Differentiation, T-Lymphocyte; Humans; Killer Cells, Natural; Lectins, C-Type; Male; NK Cell Lectin-Like Receptor Subfamily B; Oligosaccharides; Protein Structure, Tertiary; Rats
PubMed: 25690298
DOI: 10.3390/molecules20023463 -
Journal of Autoimmunity Dec 2014Although FoxP3(+) regulatory T cells are key players in the maintenance of immune tolerance and autoimmunity, the lack of specific markers constitute an obstacle to...
Although FoxP3(+) regulatory T cells are key players in the maintenance of immune tolerance and autoimmunity, the lack of specific markers constitute an obstacle to their use for immunotherapy protocols. In this study, we have investigated the role of the C-type lectin receptor CD69 in the suppressor function of Tregs and maintenance of immune tolerance towards harmless inhaled antigens. We identified a novel FoxP3(+)CD69(+) Treg subset capable to maintain immune tolerance and protect to developing inflammation. Although CD69(+) and CD69(-)FoxP3(+) Tregs exist in homeostasis, only CD69-expressing Tregs express high levels of CTLA-4, ICOS, CD38 and GITR suppression-associated markers, secrete high amounts of TGFβ and have potent suppressor activity. This activity is regulated by STAT5 and ERK signaling pathways and is impaired by antibody-mediated down-regulation of CD69 expression. Moreover, immunotherapy with FoxP3(+)CD69(+) Tregs restores the homeostasis in Cd69(-/-) mice, that fail to induce tolerance, and is also highly proficient in the prevention of inflammation. The identification of the FoxP3(+)CD69(+) Treg subset paves the way toward the development of new therapeutic strategies to control immune homeostasis and autoimmunity.
Topics: Animals; Antigens, CD; Antigens, Differentiation; Antigens, Differentiation, T-Lymphocyte; Gene Expression Regulation; Immune Tolerance; Lectins, C-Type; Mice; Mice, Inbred BALB C; Mice, Knockout; T-Lymphocytes, Regulatory; Transforming Growth Factor beta
PubMed: 24934597
DOI: 10.1016/j.jaut.2014.05.007 -
The Journal of Investigative Dermatology Jul 2011In this study, we have investigated the role of CD69, an early inducible leukocyte activation receptor, in murine dendritic cell (DC) differentiation, maturation, and...
In this study, we have investigated the role of CD69, an early inducible leukocyte activation receptor, in murine dendritic cell (DC) differentiation, maturation, and migration. Skin DCs and DC subsets present in mouse lymphoid organs express CD69 in response to maturation stimuli. Using a contact sensitization model, we show that skin DCs migrated more efficiently to draining lymph nodes (LNs) in the absence of CD69. This was confirmed by subcutaneous transfer of CD69-/- DCs, which presented an increased migration to peripheral LNs. Two-photon microscopy analysis showed that once DCs reached the LNs, CD69 deficiency did not alter DC interstitial motility in the LNs. Chemotaxis to sphingosine-1-phosphate (S1P) was enhanced in CD69-/- DCs compared with wild-type DCs. Accordingly, we detected a higher expression of S1P receptor type-1 (S1P(1)) by CD69-/- DCs, whereas S1P(3) expression levels were similar in wild-type and CD69-/- DCs. Moreover, in vivo treatment with S1P analogs SEW2871 and FTY720 during skin sensitization reduced skin DC migration to peripheral LNs. These results suggest that CD69 regulates S1P-induced skin DC migration by modulating S1P(1) function. Together, our findings increase our knowledge on DC trafficking patterns in the skin, enabling the development of new directed therapies using DCs for antigen (Ag) delivery.
Topics: Animals; Antigens, CD; Antigens, Differentiation, T-Lymphocyte; Cell Differentiation; Cell Movement; Langerhans Cells; Lectins, C-Type; Lysophospholipids; Mice; Mice, Inbred C57BL; Microscopy; Sphingosine
PubMed: 21412255
DOI: 10.1038/jid.2011.54