scholarly journals Cyclic adenosine monophosphate is a key component of regulatory T cell–mediated suppression

2007 ◽  
Vol 204 (6) ◽  
pp. 1303-1310 ◽  
Author(s):  
Tobias Bopp ◽  
Christian Becker ◽  
Matthias Klein ◽  
Stefan Klein-Heßling ◽  
Alois Palmetshofer ◽  
...  
Keyword(s):  
T Cells ◽  
Gap Junctions ◽  
Gap Junction ◽  
Molecular Mechanisms ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Peripheral Tolerance ◽  
Cell Contact ◽  
Camp Content ◽  
Naturally Occurring

Naturally occurring regulatory T cells (T reg cells) are a thymus-derived subset of T cells, which are crucial for the maintenance of peripheral tolerance by controlling potentially autoreactive T cells. However, the underlying molecular mechanisms of this strictly cell contact–dependent process are still elusive. Here we show that naturally occurring T reg cells harbor high levels of cyclic adenosine monophosphate (cAMP). This second messenger is known to be a potent inhibitor of proliferation and interleukin 2 synthesis in T cells. Upon coactivation with naturally occurring T reg cells the cAMP content of responder T cells is also strongly increased. Furthermore, we demonstrate that naturally occurring T reg cells and conventional T cells communicate via cell contact–dependent gap junction formation. The suppressive activity of naturally occurring T reg cells is abolished by a cAMP antagonist as well as by a gap junction inhibitor, which blocks the cell contact–dependent transfer of cAMP to responder T cells. Accordingly, our results suggest that cAMP is crucial for naturally occurring T reg cell–mediated suppression and traverses membranes via gap junctions. Hence, naturally occurring T reg cells unexpectedly may control the immune regulatory network by a well-known mechanism based on the intercellular transport of cAMP via gap junctions.

scholarly journals Human fetal liver MSCs are more effective than adult bone marrow MSCs for their immunosuppressive, immunomodulatory, and Foxp3+ T reg induction capacity

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Yi Yu ◽  
Alejandra Vargas Valderrama ◽  
Zhongchao Han ◽  
Georges Uzan ◽  
Sina Naserian ◽  
...  
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
Immune Responses ◽  
Molecular Mechanisms ◽  
Fetal Liver ◽  
Cytotoxic T Cells ◽  
Cell Contact ◽  
Adult Bone Marrow ◽  
Adult Bone

Abstract Background Mesenchymal stem cells (MSCs) exhibit active abilities to suppress or modulate deleterious immune responses by various molecular mechanisms. These cells are the subject of major translational efforts as cellular therapies for immune-related diseases and transplantations. Plenty of preclinical studies and clinical trials employing MSCs have shown promising safety and efficacy outcomes and also shed light on the modifications in the frequency and function of regulatory T cells (T regs). Nevertheless, the mechanisms underlying these observations are not well known. Direct cell contact, soluble factor production, and turning antigen-presenting cells into tolerogenic phenotypes, have been proposed to be among possible mechanisms by which MSCs produce an immunomodulatory environment for T reg expansion and activity. We and others demonstrated that adult bone marrow (BM)-MSCs suppress adaptive immune responses directly by inhibiting the proliferation of CD4+ helper and CD8+ cytotoxic T cells but also indirectly through the induction of T regs. In parallel, we demonstrated that fetal liver (FL)-MSCs demonstrates much longer-lasting immunomodulatory properties compared to BM-MSCs, by inhibiting directly the proliferation and activation of CD4+ and CD8+ T cells. Therefore, we investigated if FL-MSCs exert their strong immunosuppressive effect also indirectly through induction of T regs. Methods MSCs were obtained from FL and adult BM and characterized according to their surface antigen expression, their multilineage differentiation, and their proliferation potential. Using different in vitro combinations, we performed co-cultures of FL- or BM-MSCs and murine CD3+CD25−T cells to investigate immunosuppressive effects of MSCs on T cells and to quantify their capacity to induce functional T regs. Results We demonstrated that although both types of MSC display similar cell surface phenotypic profile and differentiation capacity, FL-MSCs have significantly higher proliferative capacity and ability to suppress both CD4+ and CD8+ murine T cell proliferation and to modulate them towards less active phenotypes than adult BM-MSCs. Moreover, their substantial suppressive effect was associated with an outstanding increase of functional CD4+CD25+Foxp3+ T regs compared to BM-MSCs. Conclusions These results highlight the immunosuppressive activity of FL-MSCs on T cells and show for the first time that one of the main immunoregulatory mechanisms of FL-MSCs passes through active and functional T reg induction.

scholarly journals Role of Long Non-Coding RNAs and the Molecular Mechanisms Involved in Insulin Resistance

2021 ◽  
Vol 22 (14) ◽  
pp. 7256
Author(s):  
Vianet Argelia Tello-Flores ◽  
Fredy Omar Beltrán-Anaya ◽  
Marco Antonio Ramírez-Vargas ◽  
Brenda Ely Esteban-Casales ◽  
Napoleón Navarro-Tito ◽  
...  
Keyword(s):  
Insulin Resistance ◽  
Protein Kinase ◽  
Molecular Mechanisms ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Biological Species ◽  
Necrosis Factor Alpha ◽  
Polypyrimidine Tract Binding Protein ◽  
Non Coding Rnas

Long non-coding RNAs (lncRNAs) are single-stranded RNA biomolecules with a length of >200 nt, and they are currently considered to be master regulators of many pathological processes. Recent publications have shown that lncRNAs play important roles in the pathogenesis and progression of insulin resistance (IR) and glucose homeostasis by regulating inflammatory and lipogenic processes. lncRNAs regulate gene expression by binding to other non-coding RNAs, mRNAs, proteins, and DNA. In recent years, several mechanisms have been reported to explain the key roles of lncRNAs in the development of IR, including metastasis-associated lung adenocarcinoma transcript 1 (MALAT1), imprinted maternal-ly expressed transcript (H19), maternally expressed gene 3 (MEG3), myocardial infarction-associated transcript (MIAT), and steroid receptor RNA activator (SRA), HOX transcript antisense RNA (HOTAIR), and downregulated Expression-Related Hexose/Glucose Transport Enhancer (DREH). LncRNAs participate in the regulation of lipid and carbohydrate metabolism, the inflammatory process, and oxidative stress through different pathways, such as cyclic adenosine monophosphate/protein kinase A (cAMP/PKA), phosphatidylinositol 3-kinase/protein kinase B (PI3K/AKT), polypyrimidine tract-binding protein 1/element-binding transcription factor 1c (PTBP1/SREBP-1c), AKT/nitric oxide synthase (eNOS), AKT/forkhead box O1 (FoxO1), and tumor necrosis factor-alpha (TNF-α)/c-Jun-N-terminal kinases (JNK). On the other hand, the mechanisms linked to the molecular, cellular, and biochemical actions of lncRNAs vary according to the tissue, biological species, and the severity of IR. Therefore, it is essential to elucidate the role of lncRNAs in the insulin signaling pathway and glucose and lipid metabolism. This review analyzes the function and molecular mechanisms of lncRNAs involved in the development of IR.

Effects of hormones on 3', 5' -cyclic adenosine monophosphate in choroid plexus.

1977 ◽  
Vol 232 (4) ◽  
pp. E353
Author(s):  
D Rudman ◽  
B M Hollins ◽  
N C Lewis ◽  
J W Scott
Keyword(s):  
Effective Dose ◽  
Choroid Plexus ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Tyrode Solution ◽  
Minimal Effective Dose ◽  
Camp Content ◽  
Melanocyte Stimulating Hormone ◽  
Stimulating Hormone

Choroid plexus of rabbit and rat was incubated for 2-30 min at 37 degrees C under 95% O2-5% CO2 in Tyrode solution containing 10 mM glucose and 1 mM theophylline with these agents: epinephrine, norepinephrine, isoproterenol, dopamine, histamine, serotonin, arginine, and lysine vasopressins, oxytocin, angiotensin, adrenocorticotropin (ACTH), beta-melanocyte-stimulating hormone, and choroid plexus peptide IIF. After incubation, tissue and medium were analyzed for 3', 5' -cyclic adenosine monophosphate (cAMP) content. Each amine or peptide was tested initially at 1,000 microng/ml. Only ACTH and serotonin affected cAMP content of rabbit choroid plexus. At 1,000 microng/ml, these agents caused a 10 and 4 times (respectively) increase in cAMP content of tissue + medium at 2-10 min with decline in content at 10-30 min. More than 90% of the increment was located in tissue, less than 10% in medium. Minimal effective dose (MED) to cause a significant (P less than .05) accumulation of cAMP was 0.1 microng/ml (2.2 x 10(-8) M) for ACTH and 10 microng/ml (5.7 x10(-3) M) for serotonin. Only isoproterenol, epinephrine, and norepinephrine influenced cAMP content of rat choroid plexus. MED's for this effect by isoproterenol, epinephrine, and norepinephrine were .001, .01, and 10 microng/ml (4.7 x 10(-9), 5.5 x 10(-8), and 5.9 x 10(-5) M), respectively.

scholarly journals Phosphorylation on Ser-279 and Ser-282 of connexin43 regulates endocytosis and gap junction assembly in pancreatic cancer cells

2013 ◽  
Vol 24 (6) ◽  
pp. 715-733 ◽  
Author(s):  
Kristen E. Johnson ◽  
Shalini Mitra ◽  
Parul Katoch ◽  
Linda S. Kelsey ◽  
Keith R. Johnson ◽  
...  
Keyword(s):  
Gap Junctions ◽  
Molecular Mechanisms ◽  
Pancreatic Tumor ◽  
Cell Contact ◽  
Tumor Cell Lines ◽  
Pancreatic Cancer Cells ◽  
Pancreatic Tumor Cell ◽  
Sorting Motif ◽  
Gap Junctional ◽  
Differential Phosphorylation

The molecular mechanisms regulating the assembly of connexins (Cxs) into gap junctions are poorly understood. Using human pancreatic tumor cell lines BxPC3 and Capan-1, which express Cx26 and Cx43, we show that, upon arrival at the cell surface, the assembly of Cx43 is impaired. Connexin43 fails to assemble, because it is internalized by clathrin-mediated endocytosis. Assembly is restored upon expressing a sorting-motif mutant of Cx43, which does not interact with the AP2 complex, and by expressing mutants that cannot be phosphorylated on Ser-279 and Ser-282. The mutants restore assembly by preventing clathrin-mediated endocytosis of Cx43. Our results also document that the sorting-motif mutant is assembled into gap junctions in cells in which the expression of endogenous Cx43 has been knocked down. Remarkably, Cx43 mutants that cannot be phosphorylated on Ser-279 or Ser-282 are assembled into gap junctions only when connexons are composed of Cx43 forms that can be phosphorylated on these serines and forms in which phosphorylation on these serines is abolished. Based on the subcellular fate of Cx43 in single and contacting cells, our results document that the endocytic itinerary of Cx43 is altered upon cell–cell contact, which causes Cx43 to traffic by EEA1-negative endosomes en route to lysosomes. Our results further show that gap-junctional plaques formed of a sorting motif–deficient mutant of Cx43, which is unable to be internalized by the clathrin-mediated pathway, are predominantly endocytosed in the form of annular junctions. Thus the differential phosphorylation of Cx43 on Ser-279 and Ser-282 is fine-tuned to control Cx43’s endocytosis and assembly into gap junctions.

scholarly journals Antigen-driven bystander suppression after oral administration of antigens.

1991 ◽  
Vol 174 (4) ◽  
pp. 791-798 ◽  
Author(s):  
A Miller ◽  
O Lider ◽  
H L Weiner
Keyword(s):  
T Cells ◽  
Oral Administration ◽  
Cd8 T Cells ◽  
Peripheral Tolerance ◽  
Cell Contact ◽  
Antigen Specificity ◽  
Lewis Rats ◽  
Bystander Suppression

Suppression of experimental autoimmune encephalomyelitis (EAE) in Lewis rats by the oral administration of myelin basic protein (MBP) is mediated by CD8+ T cells that can be isolated from the spleens of MBP-fed animals. These cells adoptively transfer protection to naive animals subsequently immunized with MBP and complete Freund's adjuvant (CFA) and suppress in vitro MBP proliferative responses. Using a transwell system in which the modulator spleen cells from MBP-fed animals are separated by a semipermeable membrane from responder cells, MBP, or OVA-specific T cell lines, we have found that cell contact is not required for in vitro suppression to occur. In vitro suppression is dependent, however, upon antigen-specific triggering of modulator T cells. Once antigen-specific triggering occurs, suppression across the transwell is mediated by an antigen-nonspecific soluble factor that equally suppresses an MBP line or an ovalbumin (OVA) line. This phenomenon of antigen-driven bystander suppression was also demonstrated in vivo. Specifically, Lewis rats fed OVA which were then immunized with MBP/CFA plus OVA given separately subcutaneously were protected from EAE. Animals fed OVA and then immunized with MBP/CFA without OVA given subcutaneously were not protected. The protective effect of feeding OVA could be adoptively transferred by CD8+ T cells from OVA-fed animals into MBP/CFA plus OVA-injected animals. Feeding bovine serum albumin (BSA) or keyhole limpet hemocyanin did not suppress EAE in animals immunized with MBP/CFA plus OVA. EAE was suppressed, however, if BSA was fed and animals then immunized with MBP/CFA plus BSA given subcutaneously. Antigen-driven bystander suppression appears to be an important mechanism by which antigen-driven peripheral tolerance after oral administration of antigen is mediated, and presumably occurs in the microenvironment accounting for the antigen specificity of suppression generated by oral tolerization to antigens.

Erythropoietin production: Molecular mechanisms of the antagonistic actions of cyclic adenosine monophosphate and interleukin-1

FEBS Letters ◽  
2006 ◽  
Vol 580 (13) ◽  
pp. 3153-3160 ◽  
Author(s):  
Chimedtseren Batmunkh ◽  
Jochen Krajewski ◽  
Wolfgang Jelkmann ◽  
Thomas Hellwig-Bürgel
Keyword(s):  
Molecular Mechanisms ◽  
Interleukin 1 ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Erythropoietin Production

scholarly journals Tolerogenic transcriptome landscape in CD8+ T lymphocytes after exposure to erythrocyte-targeted antigens

2018 ◽  
Author(s):  
Alizée J. Grimm ◽  
Cédric Gobet ◽  
Giacomo Diaceri ◽  
Xavier Quaglia-Thermes ◽  
Jeffrey A. Hubbell
Keyword(s):  
T Cells ◽  
T Cell ◽  
Molecular Mechanisms ◽  
Tolerance Induction ◽  
Peripheral Tolerance ◽  
Response To Treatment ◽  
Gene Expression Response ◽  
Genes Encoding ◽  
Expression Response ◽  
T Cell Phenotypes

AbstractOur group has recently shown induction of antigen-specific T cell tolerance through targeting of the antigen to erythrocytes in situ. The tolerogenic state is characterized by initial proliferation of antigen-specific T cells and subsequent acquisition of signatures associated with both deletional, anergic and regulatory T cell phenotypes. In this study we wished to further understand the molecular mechanisms behind induction of tolerance by erythrocyte-targeted antigens. RNA sequencing was performed to determine how gene expression response is regulated in tolerized ovalbumin-specific CD8+ T cells and which molecular pathways are activated after treatment with this technology. Treatment with erythrocyte-targeted antigens led to the upregulation of genes encoding several TCR co-inhibitory receptors such as CTLA4, PD1, LAG3, TIGIT and CD200R1, and lack of upregulation of cytotoxic and pro-inflammatory signaling molecule genes. Modulation in expression of the master transcription factors Egr2/NFatc1, Nur77 family and E2f1 was also observed, all known to be associated with the natural process of establishment of peripheral tolerance. Expression of these genes differed in response to treatment with soluble ovalbumin or SIINFEKL MHCI peptide, suggesting a specific mechanism of T cell modulation and tolerance induction in response to the erythrocyte-associated forms.

scholarly journals Human fetal liver MSCs are more effective than adult bone marrow MSCs for their immunosuppressive, immunomodulatory and Foxp3+ T regs induction capacity

2020 ◽  
Author(s):  
Yi Yu ◽  
Alejandra Vargas Valderrama ◽  
Zhongchao Han ◽  
Georges Uzan ◽  
Sina Naserian ◽  
...  
Keyword(s):  
Bone Marrow ◽  
T Cells ◽  
T Cell ◽  
Immune Responses ◽  
Molecular Mechanisms ◽  
Fetal Liver ◽  
Cell Contact ◽  
Adult Bone Marrow ◽  
Wide Range ◽  
Adult Bone

Abstract Background: Mesenchymal stem cells (MSCs) display active capacities of suppressing or modulating harmful immune responses through diverse molecular mechanisms. These cells are under extensive translational efforts as cell therapies for immune-mediated diseases and transplantations. A wide range of preclinical studies and limited number of clinical trials using MSCs have not only shown promising safety and efficacy profiles but have also revealed changes in regulatory T cell (T reg) frequency and function. However, the mechanisms underlying this important observation are not well understood. Cell-to-cell contact, production of soluble factors, reprogramming of antigen presenting cells to tolerogenic phenotypes have emerged as possible mechanisms by which MSCs produce an immunomodulatory environment for T reg expansion. We and others demonstrated that adult bone-marrow (BM)-MSCs suppress adaptive immune responses directly by inhibiting the proliferation of CD4+ (“helper”) and CD8+ (“cytotoxic”) T cells but also indirectly through induction of Tregs. In parallel we demonstrated that fetal liver (FL)-MSCs displays much longer-lasting immunomodulatory properties compared to BM-MSCs, by inhibiting directly the proliferation and activation of CD4+ and CD8+ T cells. Therefore, we investigated if FL-MSCs exert their strong immunosuppressive effect also indirectly through induction of T regs.Methods: MSCs were obtained from FL and adult BM and characterized according to their surface antigen expression, their multilineage differentiation and their proliferation potential. Using different in-vitro combinations, we performed co-cultures of FL or BM-MSCs and murine CD3+CD25-T cells to investigate immunosuppressive effects of MSCs on T cells and to quantify their capacity to induce functional T regs. Results: We demonstrated that although both types of MSC exhibit similar phenotypic profile and differentiation capacity, FL-MSCs have significantly higher proliferative capacity and ability to suppress both CD4+ and CD8+ murine T cell proliferation and to modulate them towards less active phenotypes than adult BM-MSCs. Moreover, their substantial suppressive effect was associated with an outstanding increase of functional CD4+CD25+Foxp3+ T regs compared to BM-MSCs.Conclusions: These results highlight the immunosuppressive activity of FL-MSCs on T cells and show for the first time that one of the main immunoregulatory mechanisms of FL-MSCs passes through active and functional T reg induction.

Potential therapeutic applications of AKAP disrupting peptides

2020 ◽  
Vol 134 (24) ◽  
pp. 3259-3282
Author(s):  
Alessandra Murabito ◽  
Sophie Cnudde ◽  
Emilio Hirsch ◽  
Alessandra Ghigo
Keyword(s):  
Protein Interactions ◽  
Molecular Mechanisms ◽  
Cyclic Adenosine Monophosphate ◽  
Adenosine Monophosphate ◽  
Pharmacological Intervention ◽  
Protein Protein Interactions ◽  
Multiprotein Complexes ◽  
Anchoring Proteins ◽  
Pka Pathway ◽  
Major Target

Abstract The 3′–5′-cyclic adenosine monophosphate (cAMP)/PKA pathway represents a major target for pharmacological intervention in multiple disease conditions. Although the last decade saw the concept of highly compartmentalized cAMP/PKA signaling consolidating, current means for the manipulation of this pathway still do not allow to specifically intervene on discrete cAMP/PKA microdomains. Since compartmentalization is crucial for action specificity, identifying new tools that allow local modulation of cAMP/PKA responses is an urgent need. Among key players of cAMP/PKA signaling compartmentalization, a major role is played by A-kinase anchoring proteins (AKAPs) that, by definition, anchor PKA, its substrates and its regulators within multiprotein complexes in well-confined subcellular compartments. Different tools have been conceived to interfere with AKAP-based protein–protein interactions (PPIs), and these primarily include peptides and peptidomimetics that disrupt AKAP-directed multiprotein complexes. While these molecules have been extensively used to understand the molecular mechanisms behind AKAP function in pathophysiological processes, less attention has been devoted to their potential application for therapy. In this review, we will discuss how AKAP-based PPIs can be pharmacologically targeted by synthetic peptides and peptidomimetics.

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