scholarly journals The scabrous gene encodes a secreted glycoprotein dimer and regulates proneural development in Drosophila eyes.

1996 ◽  
Vol 16 (3) ◽  
pp. 1179-1188 ◽  
Author(s):  
E C Lee ◽  
X Hu ◽  
S Y Yu ◽  
N E Baker
Keyword(s):  
Culture Medium ◽  
Normal Development ◽  
Photoreceptor Cells ◽  
Soluble Form ◽  
Cell Protein ◽  
Cell Contact ◽  
Primary Role ◽  
Proneural Gene ◽  
Direct Cell

R8 photoreceptor cells play a primary role in the differentiation of Drosophila eyes. In scabrous (sca) mutants, the pattern of R8 photoreceptor differentiation is altered. The sca gene is predicted to encode a secreted protein related in part to fibrinogen and tenascins. Using expression in Drosophila Schneider cells, we showed that sca encoded a dimeric glycoprotein which was secreted and found in soluble form in the tissue culture medium. The sca protein contained both N- and O-linked carbohydrates and interacted with heparin. This Schneider cell protein was similar to protein detected in embryos. We showed that sca mutations, along with conditional alleles of Notch (N) and Delta (Dl), each affected the pattern of cells expressing atonal (ato), the proneural gene required for R8 differentiation. In normal development, about 1 cell in 20 differentiates into an R8 cell; in the others, ato is repressed. N and Dl were required to repress ato in the vicinity of R8 cells, whereas sca had effects over several cell diameters. Certain antibodies detected uptake of sca protein several cells away from its source. The overall growth factor-like structure of sca protein, its solubility, and its range of effects in vivo are consistent with a diffusible role that complements mechanisms involving direct cell contact. We propose that as the morphogenic furrow advances, cell secreting sca protein control the pattern of the next ommatidial column.

scholarly journals Rotavirus Nonstructural Glycoprotein NSP4 Is Secreted from the Apical Surfaces of Polarized Epithelial Cells

2006 ◽  
Vol 80 (24) ◽  
pp. 12343-12349 ◽  
Author(s):  
Andrea Bugarc̀ić ◽  
John A. Taylor
Keyword(s):  
Culture Medium ◽  
Brefeldin A ◽  
Soluble Form ◽  
Apical Surface ◽  
Virus Particles ◽  
Bovine Rotavirus ◽  
Transmembrane Glycoprotein ◽  
Infected Cells ◽  
Dependent Pathway

ABSTRACT NSP4, a nonstructural glycoprotein encoded by rotavirus, is involved in the morphogenesis of virus particles in the endoplasmic reticulum of infected cells. NSP4 is also implicated in the pathophysiology of rotavirus-induced diarrhea by acting as an enterotoxin. To mediate enterotoxic effects in vivo, NSP4 must be secreted or released from rotavirus-infected cells in a soluble form; however, previous studies have indicated that NSP4 is a transmembrane glycoprotein localized within endomembrane compartments in infected cells. In this study, we examined the fate of NSP4 synthesized in Caco-2 cells infected with bovine rotavirus. Our studies reveal that NSP4 is actively secreted into the culture medium, preferentially from the infected-cell apical surface. The secretion of NSP4 is dramatically inhibited by brefeldin A and monensin, suggesting that a Golgi-dependent pathway is involved in release of the protein. In agreement with the proposed involvement of the Golgi apparatus during secretion, secreted NSP4 appears to undergo additional posttranslational modification compared to its cell-associated counterpart and is partially resistant to deglycosylation by endoglycosidase H. Our experiments identify a novel, soluble form of NSP4 secreted from virus-infected cells with the potential to carry out the enterotoxigenic role previously attributed to recombinant forms of the protein.

scholarly journals Comparative Analysis Between the In Vivo Biodistribution and Therapeutic Efficacy of Adipose-Derived Mesenchymal Stromal Cells Administered Intraperitoneally in Experimental Colitis

2018 ◽  
Author(s):  
Mercedes Lopez-Santalla ◽  
Pablo Mancheño-Corvo ◽  
Amelia Escolano ◽  
Ramon Menta ◽  
Olga Delarosa ◽  
...  
Keyword(s):  
Stem Cells ◽  
Inflammatory Diseases ◽  
Experimental Colitis ◽  
Similar Efficacy ◽  
Cell Contact ◽  
Adipose Derived Stem Cells ◽  
Bioluminescence Signal ◽  
Direct Cell ◽  
Promising Treatment

Mesenchymal stem cells (MSCs) have emerged as a promising treatment for inflammatory diseases. It is described that the immunomodulatory effect of MSCs takes place both by direct cell-to-cell contact and by means of soluble factors that leads to an increased accumulation of regulatory immune cells at the sites of inflammation. Similar efficacy of MSCs has been described regardless the route of administration used, the inflammation conditions and the MHC context. These observations arise the question as to whether the migration of the MSCs to the inflamed tissues is a pre-requisite to achieve their beneficial effect. To address this, we examined the biodistribution and the efficacy of intraperitoneal luciferase-expressing human expanded adipose derived stem cells (Luci-eASCs) in a mouse model of colitis. Luci-eASC-infused mice were stratified according to their response to the Luci-eASC treatment. According to the stratification criteria, there was a tendency to increase the bioluminescence signal in the intestine at the expense of a decrease in the bioluminescence signal in the liver in the `responder´ mice. These data thus suggest that the accumulation of the eASCs to the inflamed tissues is beneficial to achieve an optimal modulation of inflammation.

scholarly journals Multifaceted effects of soluble human CD6 in experimental cancer models

2020 ◽  
Vol 8 (1) ◽  
pp. e000172 ◽  
Author(s):  
Inês T Simões ◽  
Fernando Aranda ◽  
Sergi Casadó-Llombart ◽  
María Velasco-de Andrés ◽  
Cristina Català ◽  
...  
Keyword(s):  
T Cell ◽  
Cancer Cells ◽  
Ex Vivo ◽  
Lymphoid Organ ◽  
Protein Characterization ◽  
In Vivo Studies ◽  
Soluble Form ◽  
Cell Contact

BackgroundCD6 is a lymphocyte surface co-receptor physically associated with the T-cell receptor (TCR)/CD3 complex at the center of the immunological synapse. There, CD6 assists in cell-to-cell contact stabilization and modulation of activation/differentiation events through interaction with CD166/ALCAM (activated leukocyte cell adhesion molecule), its main reported ligand. While accumulating evidence is attracting new interest on targeting CD6 for therapeutic purposes in autoimmune disorders, little is known on its potential in cancer. In an attempt to elucidate the in vivo relevance of blocking CD6-mediated interactions in health and disease, we explored the consequences of expressing high circulating levels of a soluble form CD6 (sCD6) as a decoy receptor.MethodsHigh sCD6 serum levels were achieved by using transgenic C57BL/6 mice expressing human sCD6 under the control of lymphoid-specific transcriptional elements (shCD6LckEμTg) or wild type either transduced with hepatotropic adeno-associated virus coding for mouse sCD6 or undergoing repeated infusions of recombinant human sCD6 protein. Characterization of sCD6-induced changes was performed by ex vivo flow cytometry and functional analyses of mouse lymphoid organ cells. The in vivo relevance of those changes was explored by challenging mice with subcutaneous or metastatic tumors induced by syngeneic cancer cells of different lineage origins.ResultsThrough a combination of in vitro and in vivo studies, we show that circulating sCD6 expression induces defective regulatory T cell (Treg) generation and function, decreased CD166/ALCAM-mediated tumor cell proliferation/migration and impaired galectin-induced T-cell apoptosis, supporting the fact that sCD6 modulates antitumor lymphocyte effector function and tumorigenesis. Accordingly, sCD6 expression in vivo resulted in delayed subcutaneous tumor growth and/or reduced metastasis on challenge of mice with syngeneic cancer cells.ConclusionsEvidence is provided for the disruption of CD6 receptor–ligand interactions as a feasible immunomodulatory approach in cancer.

scholarly journals Direct cell–cell contact between mature osteoblasts and osteoclasts dynamically controls their functions in vivo

2018 ◽  
Vol 9 (1) ◽  
Author(s):  
Masayuki Furuya ◽  
Junichi Kikuta ◽  
Sayumi Fujimori ◽  
Shigeto Seno ◽  
Hiroki Maeda ◽  
...  
Keyword(s):  
Cell Contact ◽  
Direct Cell ◽  
Cell Cell

scholarly journals IL-15Rα chaperones IL-15 to stable dendritic cell membrane complexes that activate NK cells via trans presentation

2008 ◽  
Vol 205 (5) ◽  
pp. 1213-1225 ◽  
Author(s):  
Erwan Mortier ◽  
Tammy Woo ◽  
Rommel Advincula ◽  
Sara Gozalo ◽  
Averil Ma
Keyword(s):  
Nk Cells ◽  
Biosynthetic Pathway ◽  
Cell Activation ◽  
Nk Cell ◽  
Cell Contact ◽  
Rapid Responses ◽  
Direct Cell ◽  
Membrane Bound

Natural killer (NK) cells are innate immune effectors that mediate rapid responses to viral antigens. Interleukin (IL)-15 and its high affinity IL-15 receptor, IL-15Rα, support NK cell homeostasis in resting animals via a novel trans presentation mechanism. To better understand how IL-15 and IL-15Rα support NK cell activation during immune responses, we have used sensitive assays for detecting native IL-15 and IL-15Rα proteins and developed an assay for detecting complexes of these proteins. We find that IL-15 and IL-15Rα are preassembled in complexes within the endoplasmic reticulum/Golgi of stimulated dendritic cells (DCs) before being released from cells. IL-15Rα is required for IL-15 production by DCs, and IL-15 that emerges onto the cell surface of matured DCs does not bind to neighboring cells expressing IL-15Rα. We also find that soluble IL-15–IL-15Rα complexes are induced during inflammation, but membrane-bound IL-15–IL-15Rα complexes, rather than soluble complexes, support NK cell activation in vitro and in vivo. Finally, we provide in vivo evidence that expression of IL-15Rα specifically on DCs is critical for trans presenting IL-15 and activating NK cells. These studies define an unprecedented cytokine–receptor biosynthetic pathway in which IL-15Rα serves as a chaperone for IL-15, after which membrane-bound IL-15Rα–IL-15 complexes activate NK cells via direct cell–cell contact.

scholarly journals Activation of contact-dependent antibacterial tRNase toxins by translation elongation factors

2017 ◽  
Vol 114 (10) ◽  
pp. E1951-E1957 ◽  
Author(s):  
Allison M. Jones ◽  
Fernando Garza-Sánchez ◽  
Jaime So ◽  
Christopher S. Hayes ◽  
David A. Low
Keyword(s):  
Coiled Coil ◽  
Elongation Factor ◽  
Nuclease Activity ◽  
Ternary Complexes ◽  
Cell Contact ◽  
Translation Elongation ◽  
Direct Cell ◽  
Dependent Growth

Contact-dependent growth inhibition (CDI) is a mechanism by which bacteria exchange toxins via direct cell-to-cell contact. CDI systems are distributed widely among Gram-negative pathogens and are thought to mediate interstrain competition. Here, we describetsfmutations that alter the coiled-coil domain of elongation factor Ts (EF-Ts) and confer resistance to the CdiA-CTEC869tRNase toxin from enterohemorrhagicEscherichia coliEC869. Although EF-Ts is required for toxicity in vivo, our results indicate that it is dispensable for tRNase activity in vitro. We find that CdiA-CTEC869binds to elongation factor Tu (EF-Tu) with high affinity and this interaction is critical for nuclease activity. Moreover, in vitro tRNase activity is GTP-dependent, suggesting that CdiA-CTEC869only cleaves tRNA in the context of translationally active GTP·EF-Tu·tRNA ternary complexes. We propose that EF-Ts promotes the formation of GTP·EF-Tu·tRNA ternary complexes, thereby accelerating substrate turnover for rapid depletion of target-cell tRNA.

scholarly journals Combinatorial proteomic analysis of intercellular signaling applied to the CD28 T-cell costimulatory receptor

2015 ◽  
Vol 112 (13) ◽  
pp. E1594-E1603 ◽  
Author(s):  
Ruijun Tian ◽  
Haopeng Wang ◽  
Gerald D. Gish ◽  
Evangelia Petsalaki ◽  
Adrian Pasculescu ◽  
...  
Keyword(s):  
T Cell ◽  
Global Analysis ◽  
Membrane Receptors ◽  
Cell Contact ◽  
Intercellular Signaling ◽  
Interacting Protein ◽  
Costimulatory Receptor ◽  
Direct Cell ◽  
Cell Cell

Systematic characterization of intercellular signaling approximating the physiological conditions of stimulation that involve direct cell–cell contact is challenging. We describe a proteomic strategy to analyze physiological signaling mediated by the T-cell costimulatory receptor CD28. We identified signaling pathways activated by CD28 during direct cell–cell contact by global analysis of protein phosphorylation. To define immediate CD28 targets, we used phosphorylated forms of the CD28 cytoplasmic region to obtain the CD28 interactome. The interaction profiles of selected CD28-interacting proteins were further characterized in vivo for amplifying the CD28 interactome. The combination of the global phosphorylation and interactome analyses revealed broad regulation of CD28 and its interactome by phosphorylation. Among the cellular phosphoproteins influenced by CD28 signaling, CapZ-interacting protein (CapZIP), a regulator of the actin cytoskeleton, was implicated by functional studies. The combinatorial approach applied herein is widely applicable for characterizing signaling networks associated with membrane receptors with short cytoplasmic tails.

scholarly journals Epigenetics and Communication Mechanisms in Microglia Activation with a View on Technological Approaches

Biomolecules ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 306
Author(s):  
Sabrina Petralla ◽  
Francesca De Chirico ◽  
Andrea Miti ◽  
Ottavia Tartagni ◽  
Francesca Massenzio ◽  
...  
Keyword(s):  
3D Culture ◽  
Brain Parenchyma ◽  
Microglial Cells ◽  
Phenotypic Change ◽  
Cell Contact ◽  
Pathological Conditions ◽  
Direct Cell ◽  
The Central Nervous System ◽  
And Function

Microglial cells, the immune cells of the central nervous system (CNS), play a crucial role for the proper brain development and function and in CNS homeostasis. While in physiological conditions, microglia continuously check the state of brain parenchyma, in pathological conditions, microglia can show different activated phenotypes: In the early phases, microglia acquire the M2 phenotype, increasing phagocytosis and releasing neurotrophic and neuroprotective factors. In advanced phases, they acquire the M1 phenotype, becoming neurotoxic and contributing to neurodegeneration. Underlying this phenotypic change, there is a switch in the expression of specific microglial genes, in turn modulated by epigenetic changes, such as DNA methylation, histones post-translational modifications and activity of miRNAs. New roles are attributed to microglial cells, including specific communication with neurons, both through direct cell–cell contact and by release of many different molecules, either directly or indirectly, through extracellular vesicles. In this review, recent findings on the bidirectional interaction between neurons and microglia, in both physiological and pathological conditions, are highlighted, with a focus on the complex field of microglia immunomodulation through epigenetic mechanisms and/or released factors. In addition, advanced technologies used to study these mechanisms, such as microfluidic, 3D culture and in vivo imaging, are presented.

Acquisition of beta-glucuronidase activity by deficient fibroblasts during direct contact with lymphoid cells

1982 ◽  
Vol 55 (1) ◽  
pp. 211-231
Author(s):  
I. Olsen ◽  
M.F. Dean ◽  
H. Muir ◽  
G. Harris
Keyword(s):  
Concanavalin A ◽  
Direct Contact ◽  
Culture Medium ◽  
Lymphoid Cells ◽  
Cell Contact ◽  
3T3 Cells ◽  
Exogenous Enzyme ◽  
Glucuronidase Activity ◽  
Other Substances ◽  
Direct Cell

Fibroblasts deficient in beta-glucuronidase acquired high levels of this enzyme when they were co-cultured with concanavalin A-stimulated lymphocytes. Acquired enzyme activity, determined using a single-cell cytochemical assay, was directly proportional to the number of lymphocytes added and persisted for several days in fibroblasts maintained at high density. Lymphocytes did not secret significant levels of beta-glucuronidase into their culture medium, and did not release other substances able to induce synthesis of the enzyme by the deficient fibroblasts. Nor did beta-glucuronidase acquisition result from concanavalin A-mediated uptake of enzyme, since alpha-methylmannoside did not reduce acquired activity. Moreover, lymphocytes from various sources, whether unstimulated or activated by a different mitogen, bacterial lipopolysaccharide, were equally effective in promoting the appearance of beta-glucuronidase. Deficient fibroblasts did not acquire beta-glucuronidase by active endocytosis when co-cultured with lymphocytes, since enzyme extracted from lymphocytes was not itself effective in this respect. Furthermore, mannose 6-phosphate, which did inhibit, endocytosis by deficient fibroblasts of exogenous beta-glucuronidase prepared from 3T3 cells, had no effect on enzyme acquisition by fibroblasts during their co-culture with lymphocytes. Conversely, inhibitors of protein synthesis and energy metabolism, which did not interfere with endocytosis of exogenous enzyme, abolished the acquisition of beta-glucuronidase during co-culture. Deficient fibroblasts did not acquire beta-glucuronidase when they were cultured together with lymphocytes but separated from them by Millipore membranes permeable to exogenous enzyme. Thus, although the mechanism of acquisition is still unclear, the present results suggest that beta-glucuronidase is transferred from lymphocytes to deficient fibroblasts by a process in which direct cell-to-cell contact is obligatory.

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