Animals ; Humans ; Ligands ; Polymorphism, Genetic ; Receptor Cross-Talk ; physiology ; Receptor, Angiotensin, Type 1 ; physiology ; Receptor, Angiotensin, Type 2 ; genetics ; physiology

Receptor proteins in both eukaryotic and prokaryotic cells often form regular lattice or array in the membrane. Recent theoretical analyses indicate that such arrays may provide a novel mechanism for receptor signaling regulation in cells. The functional coupling between neighboring receptors could improve the signaling performance. The ryanodine receptors (RyR)/calcium release channels usually form 2-D regular lattice in the endoplasmic/sarcoplasmic reticulum membranes. Thus, RyR is a potentially good model to study the function of receptor 2-D array. In this article, we briefly review recent progresses in this research field, including RyR-RyR interaction, RyR array's function and working mechanisms. The investigations performed by new methods in our laboratory are summarized. We demonstrate that the RyR-RyR interaction is modulated by the functional states of RyRs. Accordingly, the mechanism of "dynamic coupling" of RyR array is proposed. Its possible role in RyR-mediated Ca(2+) release is discussed.
Animals ; Calcium ; metabolism ; Cations ; Humans ; Muscle, Skeletal ; drug effects ; metabolism ; Receptor Cross-Talk ; physiology ; Ryanodine Receptor Calcium Release Channel ; physiology ; Sarcoplasmic Reticulum ; metabolism

Toll-like receptors (TLRs) are the archetypal pattern recognition receptors in sensing exogenous pathogens. Activation of TLRs is a first line of defense of the immune system, leading to the activation and recruitment of neutrophils and macrophages to sites of infection and enhances antimicrobial activity. The TLR signaling through different intracellular molecules, such as MAP kinases and IkappaB kinases which are conserved signaling elements for many receptors, leads to a distinct set of proinflammatory gene expressions. However, how these pathways differentially and precisely control the transcription of identical genes remains largely unknown. Our review focuses on the details of up-to- date signaling molecules including negative regulators and their role in controlling innate immune response. We also stress the importance of developing systemic approaches for the global understanding of TLR signaling so that appropriate drug therapeutic targets can be identified for regulating inflammatory diseases.
Adaptor Proteins, Signal Transducing/*immunology ; Animals ; Humans ; MAP Kinase Signaling System/*immunology ; Receptor Cross-Talk ; Receptors, Interleukin-1/immunology ; *Signal Transduction ; Toll-Like Receptors/*immunology

The critical role played by stroma-epithelium crosstalk in carcinogenesis and progression of prostate cancer has been increasingly recognized. These interactions are mediated by a variety of paracrine factors secreted by cancer cells and/or stromal cells. In human prostate cancer, reactive stroma is characterized by an increase in myofibroblasts and a corresponding amplification of extracellular matrix production and angiogenesis. Permanent genetic mutations have been reported in stromal cells as well as in tumour cells. Transforming growth factor-beta, vascular endothelial growth factor, platelet-derived growth factor and fibroblast growth factor signalling pathways are involved in the process of angiogenesis, whereas hepatocyte growth factor, insulin-like growth factor-1, epidermal growth factor, CXC12 and Interleukin-6 play active roles in the progression, androgen-independent conversion and distal metastasis of prostate cancer. Some soluble factors have reciprocal interactions with androgens and the androgen receptor (AR), and can even activate AR in the absence of the androgen ligand. In this article, we review the complex interactions between cancer cells and the surrounding microenvironment, and discuss the potential therapeutic targets in the stromal compartment of prostate cancer.
Cell Communication ; physiology ; Disease Progression ; Epithelial Cells ; pathology ; physiology ; Humans ; Male ; Neovascularization, Pathologic ; physiopathology ; Prostatic Neoplasms ; pathology ; physiopathology ; Receptor Cross-Talk ; physiology ; Stromal Cells ; pathology ; physiology

OBJECTIVETo investigate the effects and the mechanisms of stanozolol (ST) on the proliferation, maturation and differentiation of in vitro cultured growth plate chondrocyte isolated from gonadotropin releasing hormone analogue (GnRHa)-treated adolescent rats, to study if ST mediates the proliferation of chondrocytes via the estrogen receptor alpha (ERalpha), androgen receptor (AR) and/or insulin-like growth factor-1 receptor (IGF-1R) and interactions of the two receptor and IGF-1R receptor signaling pathway, to investigate the mechanism of the biological effects in ST promoting bone growth/maturity at molecular level.

METHODThe rats were weaned at the end of 3 weeks and intramuscular injection of triptorelin of GnRHa preparations, qow x 2 was started. The rats were sacrificed at the end of 7 weeks, and then the tibiae growth plates were taken out with sterile procedure. The chondrocytes were obtained by two-time enzyme digestion method, and the experiments were carried out with the primary chondrocytes. Immunohistochemical staining of proliferating cell nuclear antigen (PCNA) and Western blot analysis were applied.

RESULTThe results of PCNA demonstrated that stanozolol enhanced the proliferation of the chondrocytes, time-course studies showed that the proliferation were maximally stimulated by stanozolol after 2 days of incubation and decreased again after longer periods of incubation. The expression of p-ERalpha, p-IGF-1R and p-extracellular-signal regulated kinase 1/2 (ERK1/2) increased with the incubation period of ST treatment, and reached the peak value at a certain time, and then gradually decreased. The expression of p-ERalpha, p-IGF-1R and p-ERK1/2 increased with the elevation of ST concentration, and reached the peak value at 10(-9) - 10(-8) mol/L, then gradually decreased. ST induced-p-ERalpha expression was partially blocked by ERalpha and mitogen-activated protein kinase kinase inhibitors. ST induced-p-IGF-1R expression was partially blocked by ERalpha and IGF-1R inhibitors. ST induced-p-ERK1/2 expression was partially blocked by mitogen-activated protein kinase kinase and IGF-1R inhibitors.

CONCLUSIONAs an androgen derivation, ST exerts its biological effects of promoting proliferation of the long bone growth plate chondrocytes via activating the classic ERalpha receptor pathway and mitogen-activated protein kinase pathway, and at the same time, by activation of IGF-1R. Both IGF-1R and ERalpha can promote "cross-talk" of two systems' receptor signal through mitogen-activated protein kinase signal pathway.

Androgens ; pharmacology ; Animals ; Cells, Cultured ; Chondrocytes ; cytology ; drug effects ; metabolism ; Estrogen Receptor alpha ; metabolism ; Female ; Growth Plate ; drug effects ; metabolism ; Mitogen-Activated Protein Kinase 3 ; metabolism ; Rats ; Receptor Cross-Talk ; Receptor, IGF Type 1 ; metabolism ; Signal Transduction ; drug effects ; Stanozolol ; pharmacology

Pulmonary fibrosis is a fatal progressive disease with no effective therapy. Transforming growth factor (TGF)-beta1 has long been regarded as a central mediator of tissue fibrosis that involves multiple organs including skin, liver, kidney, and lung. Thus, TGF-beta1 and its signaling pathways have been attractive therapeutic targets for the development of antifibrotic drugs. However, the essential biological functions of TGF-beta1 in maintaining normal immune and cellular homeostasis significantly limit the effectiveness of TGF-beta1-directed therapeutic approaches. Thus, targeting downstream mediators or signaling molecules of TGF-beta1 could be an alternative approach that selectively inhibits TGF-beta1-stimulated fibrotic tissue response while preserving major physiological function of TGF-beta1. Recent studies from our laboratory revealed that TGF-beta1 crosstalk with epidermal growth factor receptor (EGFR) signaling by induction of amphiregulin, a ligand of EGFR, plays a critical role in the development or progression of pulmonary fibrosis. In addition, chitotriosidase, a true chitinase in humans, has been identified to have modulating capacity of TGF-beta1 signaling as a new biomarker and therapeutic target of scleroderma-associated pulmonary fibrosis. These newly identified modifiers of TGF-beta1 effector function significantly enhance the effectiveness and flexibility in targeting pulmonary fibrosis in which TGF-beta1 plays a significant role.
Animals ; Drug Design ; Hexosaminidases/antagonists & inhibitors/metabolism ; Humans ; Lung/*drug effects/metabolism/pathology ; Molecular Targeted Therapy ; Pulmonary Fibrosis/*drug therapy/metabolism/pathology ; Receptor Cross-Talk ; Receptor, Epidermal Growth Factor/antagonists & inhibitors/metabolism ; Receptors, Transforming Growth Factor beta/antagonists & inhibitors/metabolism ; Signal Transduction ; Transforming Growth Factor beta1/*antagonists & inhibitors/metabolism

The adaptor protein, LAD/TSAd, plays essential roles in T cell activation. To further understand the functions of this protein, we performed yeast two-hybrid screening using TSAd as bait and identified 67 kDa laminin binding protein (LBP) as the interacting partner. Subsequently, TSAd-LBP interaction was confirmed in D1.1 T cell line. Upon costimulation by T cell receptor (TCR) plus laminin crosslinking or TCR plus integrin alpha6 crosslinking, LBP was coimmunoprecipitated with TSAd. Moreover, TCR plus laminin costimulation-dependent T cell migration was enhanced in D1.1 T cells overexpressing TSAd but was disrupted in D1.1 cells overexpressing dominant negative form of TSAd or TSAd shRNA. These data show that, upon TCR plus integrin costimulation, TSAd associates with LBP and mediates T lymphocyte migration.
Adaptor Proteins, Signal Transducing/genetics/*metabolism ; Amino Acids, Diamino/metabolism ; Carrier Proteins/*metabolism ; *Cell Movement ; Humans ; Integrin alpha6/metabolism ; Jurkat Cells ; Mutation ; Protein Binding ; RNA, Small Interfering/genetics ; *Receptor Cross-Talk ; Receptors, Antigen, T-Cell/metabolism ; T-Lymphocytes/*metabolism ; Transgenes ; Two-Hybrid System Techniques

The nuclear receptors, steroid and xenobiotic receptor (SXR) and constitutive androstane receptor (CAR) play important functions in mediating lipid and drug metabolism in the liver. The present study demonstrates modulatory actions of estrogen in transactivations of SXR-mediated liver X receptor response element (LXRE) and CAR-mediated phenobarbital response element (PBRU). When human estrogen receptor (hERalpha) and SXR were exogenously expressed, treatment with either rifampicin or corticosterone promoted significantly the SXR-mediated transactivation of LXRE reporter gene in HepG2. However, combined treatment with estrogen plus either rifampicin or corticosterone resulted in less than 50% of the mean values of the transactivation by rifampicin or corticosterone alone. Thus, it is suggested that estrogen may repress the SXR-mediated transactivation of LXRE via functional cross-talk between ER and SXR. The CAR-mediated transactivation of PBRU was stimulated by hERalpha in the absence of estrogen. However, the potentiation by CAR agonist, TCPOBOP, was significantly repressed by moxestrol in the presence of ER. Thus, ER may play both stimulatory and inhibitory roles in modulating CAR-mediated transactivation of PBRU depending on the presence of their ligands. In summary, this study demonstrates that estrogen modulates transcriptional activity of SXR and CAR in mediating transactivation of LXRE and PBRU, respectively, of the nuclear receptor target genes through functional cross-talk between ER and the corresponding nuclear receptors.
Corticosterone/pharmacology ; Estrogens/*metabolism ; Ethinyl Estradiol/analogs & derivatives/pharmacology ; Hep G2 Cells ; Humans ; Liver/*metabolism ; Orphan Nuclear Receptors/metabolism ; Phenobarbital/metabolism ; Pyridines/pharmacology ; Receptor Cross-Talk ; Receptors, Cytoplasmic and Nuclear/agonists/*metabolism ; Receptors, Steroid/*metabolism ; Response Elements ; Rifampin/pharmacology ; Transcriptional Activation/*drug effects/physiology

Myasthenia gravis (MG) is a prototypical antibody-mediated neurological autoimmune disease with the involvement of humoral immune responses in its pathogenesis. T follicular helper (Tfh) cells have been implicated in many autoimmune diseases. However, whether and how Tfh cells are involved in MG remain unclear. Here, we established and studied a widely-used and approved animal model of human MG, the rat model with acetylcholine receptor alpha (AChRα) subunit (R-AChR)-induced experimental autoimmune myasthenia gravis (EAMG). This model presented mild body-weight loss 10 days after the first immunization (representing the early stage of disease) and more obvious clinical manifestations and body-weight loss 7 days after the second immunization (representing the late stage of disease). AChR-specific pre-Tfh cells and mature Tfh cells were detected in these two stages, respectively. In co-cultures of Tfh cells and B cells, the number of IgG2b-secreting B cells and the level of anti-AChR antibodies in the supernatant were higher in the cultures containing EAMG-derived Tfh cells. In immunohistochemistry and immunofluorescence assays, a substantial number of CD4/Bcl-6 T cells and a greater number of larger germinal centers were observed in lymph node tissues resected from EAMG rats. Based on these results, we hypothesize that an AChR-specific Tfh cell-mediated humoral immune response contributes to the development of EAMG.
Animals ; B-Lymphocytes ; immunology ; Disease Models, Animal ; Female ; Immunity, Humoral ; Lymph Nodes ; immunology ; Myasthenia Gravis, Autoimmune, Experimental ; immunology ; Protein Subunits ; immunology ; Proto-Oncogene Proteins c-bcl-6 ; immunology ; Rats, Inbred Lew ; Receptor Cross-Talk ; Receptors, Cholinergic ; immunology ; T-Lymphocytes, Helper-Inducer ; immunology

Previously we demonstrated that ATP released from LPS-activated microglia induced IL-10 expression in a process involving P2 receptors, in an autocrine fashion. Therefore, in the present study we sought to determine which subtype of P2 receptor was responsible for the modulation of IL-10 expression in ATP-stimulated microglia. We found that the patterns of IL-10 production were dose-dependent (1, 10, 100, 1,000 micrometer) and bell-shaped. The concentrations of ATP, ATP-gammaS, ADP, and ADP-beta S that showed maximal IL-10 release were 100, 10, 100, and 100 micrometer respectively. The rank order of agonist potency for IL-10 production was 2'-3'-O-(4-benzoyl)-benzoyl ATP (BzATP) = dATP > 2-methylthio-ADP (2-meSADP). On the other hand, 2-methylthio-ATP (2-meSATP), alpha,beta-methylene ATP (alpha,beta-meATP), UTP, and UDP did not induce the release of IL-10 from microglia. Further, we obtained evidence of crosstalk between P2 receptors, in a situation where intracellular Ca2+ release and/or cAMP-activated PKA were the main contributors to extracellular ATP-(or ADP)-mediated IL-10 expression, and IL-10 production was down- regulated by either MRS2179 (a P2Y1 antagonist) or 5'-AMPS (a P2Y11 antagonist), indicating that both the P2Y1 and P2Y11 receptors are major receptors involved in IL-10 expression. In addition, we found that inhibition of IL-10 production by high concentrations of ATP-gammaS (100 micrometer) was restored by TNP-ATP (an antagonist of the P2X1, P2X3, and P2X4 receptors), and that IL-10 production by 2-meSADP was restored by 2meSAMP (a P2Y12 receptor antagonist) or pertusis toxin (PTX; a Gi protein inhibitor), indicating that the P2X1, P2X3, P2X4 receptor group, or the P2Y12 receptor, negatively modulate the P2Y11 receptor or the P2Y1 receptor, respectively.
Adenosine Diphosphate/analogs & derivatives/pharmacology ; Adenosine Triphosphate/analogs & derivatives/*pharmacology ; Adenylate Cyclase/antagonists & inhibitors ; Animals ; Calcium/metabolism ; Chelating Agents/pharmacology ; Cyclic AMP-Dependent Protein Kinases/antagonists & inhibitors ; Enzyme Inhibitors/pharmacology ; Extracellular Space/drug effects/*metabolism ; Gene Expression Regulation/drug effects ; Interleukin-10/*biosynthesis ; Microglia/*drug effects/enzymology/*metabolism ; RNA, Messenger/genetics/metabolism ; Rats ; Rats, Sprague-Dawley ; Receptor Cross-Talk/*drug effects ; Receptors, Purinergic P2/agonists/antagonists & inhibitors/genetics/*metabolism ; Thionucleotides/pharmacology