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The molecular basis of vascular stabilization regulated by sphingosine 1-phosphate (S1P), a platelet-derived lipid mediator is investigated. S1P-induced trafficking and activation of N-cadherin provides a novel mechanism for the stabilization of nascent blood vessels by mural cells and may be exploited to control angiogenesis and vascular diseases.

Coregulator DIN-1 and DAF-12 is shown interacting physically and genetically to instruct organismal fates. It is proposed that the DIN-1S/DAF-12 complex serves as a molecular switch that implements slow life history alternatives in response to diminished hormonal signals.

Ryanodine receptors (RyRs) are Ca(super ++) channels that control cellular functions. An estimation of the RyR2 ion diffusion constants and electrostatic interactions, in a self-consistent coherent formulation, is provided by the extended PNP.

Byline: V. P. Marinina (1), A. S. Gambaryan (1), N. V. Bovin (2), A. B. Tuzikov (2), A. A. Shilov (3), B. V. Sinitsyn (3), M. N. Matrosovich (1) Keywords: influenza viruses; glycosylation sites; receptors Abstract: The receptor properties of influenza virus A/USSR/90/77 isolates are studied. The isolates are peculiar for losing glycosylation sites at the Asn131 receptor-binding region (GS131) after passaging in mice and at the Asn158 region (GS158) after cultivation in the presence of mouse serum. The loss of each carbohydrate residue increases the influenza virus affinity for carbohydrate chains with the terminal group Neu5Ac[alpha]2-6Gal and reduces its affinity for Neu5Ac[alpha]2-3Gal receptors. The effect is more pronounced in the GS158-depleted virus. Upon substitution of asparagine by aspartic acid, the electrostatic component of virus binding to the receptor is altered because of the increased negative charge on hemagglutinin. The virus receptor phenotype changes depending on the cultivation conditions. The isolate adapted to mice has higher affinity to mouse lung cell receptors, while the virus propagated in chick embryos in the presence of inhibitors has higher affinity to allantoic membrane cells. Author Affiliation: (1) Chumakov Institute of Poliomyelitis and Viral Encephalitides, Russian Academy of Sciences, Moscow, 142782, Russia (2) Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry, Russian Academy of Sciences, Moscow, 117997, Russia (3) Ivanovsky Institute of Virology, Russian Academy of Medical Sciences, Moscow, 123098, Russia Article History: Registration Date: 12/10/2004

Byline: A. S. Gambaryan (1), S. S. Yamnikova (2), D. K. Lvov (2), J. S. Robertson (3), R. G. Webster (4), M. N. Matrosovich (1) Keywords: influenza viruses; evolution; species barrier; receptors; gangliosides Abstract: The affinity of the duck, chicken, and human influenza viruses to the host cell sialosides was determined, and considerable distinctions between duck and chicken viruses were found. Duck viruses bind to a wide range of sialosides, including the short-stem gangliosides. Most of the chicken viruses, like human ones, lose the ability to bind these gangliosides, which strictly correlates with the appearance of carbohydrate at position 158--160. The affinity of the chicken viruses to sialoglycoconjugates of chicken intestine as well as chicken, monkey, and human respiratory epithelial cells exceeds that of the duck viruses. The human influenza viruses have high affinity to the same cells but do not bind at all to the duck epithelial cell. This testifies to the absence of 6'-sialylgalactose residues from the duck cells, in contrast to chicken and monkey cells. The alteration of the receptor specificity of chicken viruses in comparison with duck ones results in the similarity of the patterns of accessible cells for chicken and human influenza viruses. This may be the cause of the appearance of the line of H9N2 viruses from Hong Kong live bird markets with receptor specificity similar to that of H3N2 human viruses, and of the ability of H5N1 and H9N2 chicken influenza viruses to infect humans. Author Affiliation: (1) Chumakov Institute of Poliomyelitis and Viral Encephalitides, Russian Academy of Medical Sciences, Moscow Region, 142782, Russia (2) Ivanovsky Institute of Virology, Moscow, 123098, Russia (3) National Institute for Biological Standards and Control, Herts, EN6 3QG, UK (4) Department of Virology and Molecular Biology, St. Jude Children's Research Hospital, Memphis, Tennessee, 38105-2794, USA Article History: Registration Date: 09/10/2004

Byline: K. V. Bol'shakov (1), S. L. Buldakova (1) Keywords: AMPA receptors; hippocampus; kainate; cyclothiazide; channel blockers; interneurons Abstract: Experiments were performed on isolated neurons from hippocampal field CA1 and the dentate fascia to identify the subunit composition and distribution of splicing variants of AMPA receptor subunits. Currents evoked by the application of kainate were recorded using a whole-cell patch clamping method. The presence of GluR2 subunits in receptors was associated with a sharp reduction in the activity of the selective channel blocker IEM-1460. The composition of flip versions of subunits was assessed using cyclothiazide. AMPA receptors in the major cell types (pyramidal and granule cells) had low sensitivity to IEM-1460, while AMPA receptors of other cells (interneurons) had high or intermediate sensitivity. Cyclothiazide had strong potentiating effects on the main cell types in both structures as compared with interneurons. Thus, there is a correlation between the sensitivities of hippocampal neurons to IEM-1460 and cyclothiazide. The main cell types in both structures expressed large quantities of the GluR2 subunit in their AMPA receptors, with high levels of flip subunits, as compared with the other cell types, in which GluR2 subunits were virtually absent and the flop version predominated. This appears to reflect the functional features of different types of neurons. Author Affiliation: (1) Russian Academy of Sciences, I. M. Sechenov Institute of Evolutionary Physiology and Biochemistry, 44 M. Torez Prospekt, 194223, St. Petersburg, Russia Article History: Registration Date: 08/10/2004

Byline: K. N. Dudkin (1), V. K. Kruchinin (1), I. V. Chueva (1) Keywords: rhesus macaque; visual recognition; short-term memory; visual cortex; neurons; spike activity; glutamatergic system; APV; desynchronization of activity Abstract: The effects of perfusion of field 17 with the glutamate receptor antagonist 2-amino-5-phosphonovaleric acid (APV) on the characteristics of visual recognition and short-term memory were studied, along with the effects of APV on the responses of neurons in the visual and prefrontal areas of the cortex in rhesus macaques. In the test for delayed visual differentiation of stimuli of different colors, behavioral data were recorded simultaneously with multichannel recordings of the spike activity of single cells in cortical field 17 (directly within the microdialysis zone) and field 8. Multifactor dispersion analysis (ANOVA) showed that APV significantly worsened the behavioral characteristics in monkeys, with significant reductions in the duration of short-term storage of information (by factors of 2--4) and significant increases in the motor response times. These changes in cognitive characteristics induced by APV were accompanied by changes in the spike activity of neurons in the visual and prefrontal areas of the cortex during the sensory analysis and delay stages changes in spike activity consisted of significant desynchronization. These results show that cognitive dysfunctions consisting of worsening of short-term remembering of information and increases in the duration of motor responses during exposure to APV may be caused by desynchronization of neuron activity in various areas of the cortex, these being involved in neuron ensembles responsible for the mechanisms of short-term memory, in which glutamatergic structures play an important role. Author Affiliation: (1) Russian Academy of Sciences, I. P. Pavlov Institute of Physiology, 6 Makarov Bank, 19934, St. Petersburg, Russia Article History: Registration Date: 08/10/2004

In response to antigenic stimuli, the multi-subunit immune recognition receptors become aggregated and then phosphorylated on their cytoplasmic tyrosines. For the clonotypic receptors of B and T cells and for Fc receptors such as the high-affinity receptor for IgE (Fc[Epsilon]RI), a Src family kinase initiates this phosphorylation. We ask whether aggregation of the initiating kinase itself is required for signal transduction or whether, alternatively, a single associated kinase molecule can phosphorylate the receptors in an aggregate. We formulate the alternative molecular mechanisms mathematically and compare predictions with experimental findings on Fc[Epsilon]RI-bearing cells expressing varying amounts of the transfected Src family kinase Lyn. The data are consistent with the requirement of only a single Lyn molecule per Fc[Epsilon]RI aggregate to initiate signaling and are inconsistent with a mechanism requiring more than one Lyn molecule.

A study was conducted to determine the relationship between cholecystokinin (CCK) and serotonin (5-HT) in fat-induced satiety in rats. Selective receptor antagonists were used in the study to elucidate the roles of the two chemical modulators in fat-induced satiety. The antagonists Devazepide and Tropisetron were found in combination to completely block the satiating effects of the 80% fat infusate on all feeding variables that were measured. The results suggest that both endogenous 5-HT and CCK play a role in the satiety response to fat in the intestine.

A study was conducted to provide more evidence to the hypothesis that only dietary protein (Pro) and not fats (Fat), carbohydrates (CHO), or amino acids (AA) suppresses appetite in rats through CCK receptors. To test the hypothesis, the CCK-A receptor antagonists devazepide and PD-140,548, were administered intraperitoneally. The results brought more confirmation to the hypothesis as the antagonists were found to reverse Pro-induced suppression of appetite, while failing to modulate Fat-, CHO-, or AA-induced reduction of food intake.

The voltage-gated sodium channel is the site of action of more than six classes of neurotoxins and drugs that alter its function by interaction with distinct, allosterically coupled receptor sites. Batrachotoxin (BTX) is a steroidal alkaloid that binds to neurotoxin receptor site 2 and causes persistent activation. BTX binding is inhibited allosterically by local anesthetics. We have investigated the interaction of BTX with amino acid residues 11760, F1764, and Y1771, which form part of local anesthetic receptor site in transmembrane segment IVS6 of type IIA sodium channels. Alanine substitution for F1764 (mutant F1764A) reduces tritiated BTX-A-20-[Alpha]-benzoate binding affinity, causing a 60-fold increase in [K.sub.d]. Alanine substitution for I1760, which is adjacent to F1764 in the predicted IVS6 transmembrane alpha helix, causes only a 4-fold increase in [K.sub.d]. In contrast, mutant Y1771A shows no change in BTX binding affinity. For wild-type and mutant Y1771A, BTX shifted the voltage for half-maximal activation [approximately equal to]40 mV in the hyperpolarizing direction and increased the percentage of noninactivating sodium current to [approximately equal to]60%. In contrast, these BTX effects were eliminated completely for the F1764A mutant and were reduced substantially for mutant I1760A. Our data suggest that the BTX receptor site shares overlapping but nonidentical molecular determinants with the local anesthetic receptor site in transmembrane segment IVS6 as well as having unique molecular determinants in transmembrane segment IS6, as demonstrated in previous work. Evidently, BTX conforms to a domain-interface allosteric model of ligand binding and action, as previously proposed for calcium agonist and antagonist drugs acting on L-type calcium channels.

The anti-idiotype approach is based on the assumption that an antibody specific for a receptor-binding domain of a ligand could be structurally related to the receptor. Therefore, a structural mimic of a receptor-binding domain, selected with an anti-ligand antibody, might be a functional substrate for the receptor. This hypothesis was addressed here by generating antibodies recognizing the Rev-nuclear export signal (NES). A functional NES is required for active export, presumably by interacting directly or indirectly with the nuclear pore complex. Anti-NES antibodies were used to isolate RNA mimics of the NES peptide from combinatorial RNA libraries. The RNA-mimics are exported actively, block Rev-dependent export of a reporter RNA, and inhibit cap-dependent U1 snRNA export in Xenopus oocytes, properties previously reported for NES-peptide conjugates.

Characterization of nine consecutive residues in a transmember segment of the proposed Beta-strand of the ferric enterobactin receptor FepA active site loop through electron paramagnetic resonance (EPR) site-directed spin-labeling found that the residues adopt a Beta-strand secondary structure bridging the lipid bilayer. Alternate residues fact the lipid alkyl chains and the aqueous interior of the channel. Strong tertiary interactions in the extracellular half of the strand suggest strand-loop interactions.

Synthesis and examination of disaccharide polyphosphates based upon adenophostin A revealed that all analogs mobilized the same intracellular Ca2+ pool as Ins(1,4,5)P3 and adenophostin A but none was as potent as adenophostin A. Results indicate that Rib(2,3',4')P3 is as potent as Ins(1,4,5)P3, more potent than most inositol-based agoninsts, but is not as potent than adenophostins. Data show that phophorylated disaccharides provide for the development of high affinity ligands of Ins(1,4,5)P3 receptors.

An examination of an in vitro model of the blood-brain barrier (BBB) found that low density lipoprotein (LDL) transcytosis across the monolayer is mediated by the receptor. Results show that cholesterol-depleted astrocyles control the expression of the LDL receptor at the BBB and that LDL transcytosis runs parallel to the increase in LDL receptor. Data from preliminary studies indicate that caveolae may be involved in the transport of LDL from the blood to the brain.

Although coronary artery disease (CAD) is appreciated to be accelerated in patients with chronic spinal cord injury (SCI), the underlying mechanism of CAD in SCI remains obscure. We have recently shown that platelets from subjects with SCI develop resistance to the inhibitory effect of prostacyclin (PG[I.sub.2]) on the platelet stimulation of thrombin generation. The loss of the inhibitory effect was due to the loss of high-affinity prostanoid receptors, which may contribute to atherogenesis in SCI. Incubation of normal, non-SCI platelets in SCI plasma (n = 12) also resulted in the loss of high-affinity binding of PG[I.sub.2] (K[d.sub.1] = 9.1 [+ or -] 2.0 nM; [n.sub.1] = 170 [+ or -] 32 sites per cell vs. K[d.sub.1] = 7.2 [+ or -] 1.1 nM; [n.sub.1] = 23 [+ or -] 8 sites per cell), with no significant change in the low-affinity receptors (K[d.sub.2] = 1.9 [+ or -] 0.1 [[micro]molar]; [n.sub.2] = 1,832 [+ or -] 232 sites per cell vs. K[d.sub.2] = 1.6 [+ or -] 0.1 [[micro]molar]; [n.sub.2] = 1,740 [+ or -] 161 sites per cell) as determined by Scatchard analysis of the binding of [3H]PG[E.sub.1]. The loss of high-affinity PG[I.sub.2] binding led to the failure of PG[I.sub.2] to inhibit the platelet-stimulated thrombin generation. The increase of cellular cyclic AMP level, mediated through the binding of PG[I.sub.2] to low-affinity receptors in platelets, was unaffected in SCI platelets. PAGE and immunoblot of SCI plasma showed the presence of an IgG band, which specifically blocked the binding of [3H]PG[E.sub.1] to the high-affinity PG[I.sub.2] receptors of normal platelets. PAGE of the reduced IgG band, the amino acid sequence of the novel band as a heavy chain of IgG that inhibits the binding of [3H]PG[E.sub.1] to the high-affinity platelet PG[I.sub.2] receptor, demonstrates that the specific recognition and inhibition of high-affinity PG[I.sub.2] binding to platelets was due to an anti-prostacyclin receptor antibody present in SCI plasma.

Research was conducted to study the effects of M2 and M3 receptor antagonists and antibodies directed against specific G protein subunits on the activation of Icat by methacholine using simultaneous measurements of intracellular Ca2+ concentration ([Ca2+]1) and current in voltage-clamped isolated equine tracheal myocytes. Activation of M2 receptors leads to the opening of nonselective cation channels through Gi/Go proteins in smooth muscle cells, resulting in a sustained rise in [Ca2+]i. A rise in [Ca2+]i is necessary but not sufficient to activate nonselective cation channels.

An investigation of the importance of B-loop sequences in determining receptor activation has been conducted. The study also sought to understand their causal role in the antagonistic activity of the Argos ligand. The results showed that a number of nonconservative substitution in the human epidermal growth factor B-loop are tolerated without any effect on receptor binding or activation. They also indicate that both receptor binding and signaling efficiency can be uncoupled, a prerequisite for receptor antagonist development.

The presence of the cell-adhesion protein P-selectin and its ligand P-selectin glycoprotein ligand-1 (PSGL-1) in the zona pellucida of porcine was observed. The P-selectin ligand from the porcine zona pellucida was found to share similar biochemical, functional, and polypeptide properties with the human leukocyte PSGL-1. The distribution of the ligand in the zona pellucida indicates that it is likely to be located in the membranes embedded within the zona pellucida matrix. P-selectin was also observed to be present in the acrosomal membrane of porcine sperm cells.

The androgen receptor (AR) is a member of the steroid receptor superfamily that plays an important role in male sexual differentiation and prostate cell proliferation. Mutations or abnormal expression of AR in prostate cancer can play a key role in the process that changes prostate cancer from androgen-dependent to an androgen-independent stage. Using a yeast two-hybrid system, we were able to isolate a ligand-dependent AR-associated protein ([ARA.sub.70]), which functions as an activator to enhance AR transcriptional activity 10-fold in the presence of [10.sup.-10] M dihydrotestosterone or [10.sup.-9] M testosterone, but not [10.sup.-6] M hydroxyflutamide in human prostate cancer DU145 cells. Our data further indicated that [ARA.sub.70] will only slightly induce the transcriptional activity of other steroid receptors such as estrogen receptor, glucocorticoid receptor, and progesterone receptor in DU145 cells. Together, these data suggest that AR may need a specific coactivator(s) such as [ARA.sub.70] for optimal androgen activity.

Neutrophils use a variety of cell-surface receptors for attachment to surfaces, such as the endothelium or opsonized pathogens. During inflammation or infection, chemoattractants or cytokines bind to neutrophils and upregulate or 'prime' their responsiveness. Priming can increase the number of some receptors expressed on the cell surface but can also change receptor function, so that the receptor has altered ligand-binding properties or becomes linked to new intracellular signalling systems.

Two single-chain intracellular antibodies have been used to downregulate the high-affinity human interleukin 2 receptor (IL-2R-alpha). In stimulated Jurkat T cells the intracellular expression of a single-chain antibody, a fragment of the anti-Tac monoclonal antibody, completely inhibits cell surface expression of IL-2R-alpha. Also a single-chain antibody without the endoplasmic reticulum retention signal blocks the cell surface expression of IL-2R-alpha.

The numerous and widespread effects of adenosine provide both an opportunity for the development of novel therapeutic agents acting via adenosine receptors and the challenge of achieving selectivity of action. The feasibility of achieving selectivity is enhanced if receptor subtypes can be identified. Biochemical, functional and receptor-cloning studies are beginning to provide convergent data supporting the existence of A(sub 1), A(sub 2A), A(sub 2B) and A(sub 3) receptors. However, studies of the functional significance of these receptors in intact tissues both in vitro and in vivo have lagged behind the biochemical studies. In this article, Michael Collis and Susanna Hourani review the current status of adenosine receptor classification and propose that ligands with greater selectivity need to be evaluated in a wide range of functional preparations if the therapeutic potential of this area is to be realized.

The only known pathogenic human parvovirus, B19 parvovirus, causes the common illness fifth disease in normal individuals[1], transient aplastic crisis in patients with underlying hemolysis[2], and chronic anemia from persistent [...], The pathogenic human parvovirus B19 replicates only in erythroid progenitor cells. This virus was shown to bind to blood-group P antigen, as measured by hemagglutination. Erythrocytes lacking P antigen were not agglutinated with B19. Purified P antigen (globoside) blocked the binding of the virus to erythroid cells and the infectivity of the virus in a hematopoietic colony assay. Target cells were protected from infection by preincubation with monoclonal antibody to globoside. Knowledge of a parvovirus receptor has implications for understanding the pathogenesis of parvovirus infections and for the use of parvoviruses in gene therapy.

The availability of catalytic sequences was examined using anti-peptide antibodies generated against highly conserved sites in the kinase domain and two nonconserved sequences around autophosphorylation sites in the epidermal growth factor receptor (EGFR) carboxyl-terminal domain. Results revealed that only alphaHRD and alphaDFG had an inhibitory effect on EGFR kinase activity, suggesting that the sites HRD and DFG were involved in catalysis. Except for that found in the HRD site, all epitopes were found to be exposed to antibody binding.

A comparative study was conducted on the dynamic conformations of the immunoglobulin (Ig) isotopes murine IgE and human IgG1. Results show that both Ig have a carboxy-terminal domain. The average end-to-end distance for both Ig were also determined. IgG1 in solution displayed more flexibility than IgE and this was attributed to IgG1's shorter average end-to-end distance measurement.

A study was conducted on the phenomenon of ligand mimicry by anti-receptor antibodies. The generation and properties of the anti-receptor antibodies that react with the ligand binding site were analyzed and were found to have vital structural and therapeutic implications. Similar amino acids and side-chain geometries were found to be useful for reovirus type 3 and influenza hemagglutinins in their interactions with cell-surface receptors. The peptide and nonpeptide mimetics can also be therapeutically useful in cases such as treatment of thyroid disease and hypercoagulation states.

The murine monoclonal antibody mumAb4D5 inhibits the growth of tumor cells overexpressing p185(super HER2), a tyrosine kinase homologous the human epidermal growth factor. To achieve the use of mumAb4D5 in human therapy, humanized antibodies (humAb4D5) were constructed using a new procedure temed as 'gene conversion mutagenesis.' Different variants of humAb4D5 could bind to p185(HER2) antigen up to three-fold more tightly than the parental murine form. In addition, humAb4D5-8 is almost as potent as the murine parent in blocking the proliferation of SK-BR-3 cells.

The importance of tyrosine phosphorylation during ligand-induced internalization of membrane immunoglobulin (mIg) and its critical role for activating B cells as antigen presenting cells were investigated. Two tyrosine phosphorylation specific inhibitors inhibited mIg modulation on the cell surface and suppressed ligand-induced receptor internalization. These findings indicated that tyrosine phosphorylation in the B cells occured as a consequence of crosslinking mIg and was needed for internalization of mIg-ligand complexes. The results supported the essential role of tyrosine phosphorylation in the function of B lymphocytes.

Long-lived organisms are constantly being attacked by a myriad of pathogens that have evolved mechanisms to evade the host immune system. To counter this onslaught, vertebrate T and B lymphocytes [...], A study of lymphocytes that lack a DNA-repair enzyme challenges long-standing dogma about the spatial separation of processes that rearrange antibody genes, and provides clues about the origins of B-cell cancers.

Natural killer (NK) cells are lymphocytes of the innate immune system that are involved in early defenses against both allogeneic (nonself) cells and autologous cells undergoing 2various forms of stress, [...], Natural killer (NK) cells are lymphocytes of the innate immune system that are involved in the early defenses against foreign cells, as well as autologous cells undergoing various forms of stress, such as microbial infection or tumor transformation. NK cell activation is controlled by a dynamic balance between complementary and antagonistic pathways that are initiated upon interaction with potential target cells. NK cells express an array of activating cell surface receptors that can trigger cytolytic programs, as wet[ as cytokine or chemokine secretion. Some of these activating cell surface receptors initiate protein tyrosine kinase (PTK)-dependent pathways through noncovalent associations with transmembrane signaling adaptors that harbor intracytoplasmic ITAMs (immunoreceptor tyrosine-based activation motifs). Additional cell surface receptors that are not directly coupled to ITAMs also participate in NK cell activation. These include NKGZD, which is noncovalently associated to the DAP10 transmembrane signaling adaptor, as well as integrins and cytokine receptors. NK cells also express cell surface inhibitory receptors that antagonize activating pathways through protein tyrosine phosphatases (PTPs). These inhibitory cell surface receptors are characterized by intracytoplasmic ITIMs (immunoreceptor tyrosine-based inhibition motifs). The tyrosine-phosphorylation status of several signaling components that are substrates for both PTKs and PTPs is thus key to the propagation of the NK cell effector pathways. Understanding the integration of these multiple signals is central to the understanding and manipulation of NK cell effector signaling pathways.

Calcium-sensing receptor (CaSR) is represented by the seven-transmembrane-spanning G protein-coupled receptors on the surface of the parathyroid cell. The discovery and research about the calcium-sensing receptor serves as a paradigm for translational research.

Receptor tyrosine kinases (RTKs) control many of the biochernical processes that regulate cellular homeostasis (1, 2). Given their importance, RTKs are themselves subject to multiple levels of control (2). A [...]

A study was conducted to understand why it is hard to design a high-affinity receptor and to explore the limits of affinity, with bioactive peptide RGD as a model ligand was conducted. The analysis of the computed efficiencies suggested that a low molecular weight receptor could achieve protein like affinity.

Cholapod anion receptors are capable of high affinities while retaining compatibility with nonpolar organic media. Among the 13 receptors studied, the structures include between three and six H-bond donors sited in urea, thiourea, sulfonamide, carbamate, trofluoroacetamide and isophthalamide binding units.

The binding of mono- and bivalent forms of the receptors B cell maturation protein (BCMA) and B cell activating factor of the TNF family (BAFF) receptor, BAFFR to BAFF and a proliferation-inducing ligand, APRIL are characterized. The quantitative assessment of the affinity of receptor binding to each ligand is made possible by using soluble, mono- and bivalent forms of these candidate receptors.

Although first introduced for the treatment of hypogammaglobulinemia, IVIG has since been shown to have broad therapeutic applications in the treatment of infectious and inflammatory diseases (1). The polyclonal specificities [...], The molecular basis for the anti-inflammatory property of intravenous gamma globulin (IVIG) was investigated in a murine model of immune thrombocytopenia. Administration of clinically protective doses of intact antibody or monomeric Fc fragments to wild-type or Fc[Gamma] receptor-humanized mice prevented platelet consumption triggered by a pathogenic autoantibody. The inhibitory Fc receptor, Fc[Gamma]RIIB, was required for protection, because disruption either by genetic deletion or with a blocking monoclonal antibody reversed the therapeutic effect of IVIG. Protection was associated with the ability of IVIG administration to induce surface expression of Fc[Gamma]RIIB on splenic macrophages. Modulation of inhibitory signaling is thus a potent therapeutic strategy for attenuating autoantibody-triggered inflammatory diseases.

For more than halt a century, patients with antibody deficiencies have been treated with intravenous injections of immunoglobulin (IVIG). IVIG is prepared from pooled serum and its major component is [...]

Nuclear receptors constitute a large family of ligand-modulated transcription factors that mediate cellular responses to small lipophilic molecules, including steroids, retinoids, fatty acids, and exogenous ligands. Orphan nuclear receptors with no known endogenous ligands have been discovered to regulate drug-mediated induction of cytochromes P450 (CYP), the major drug-metabolizing enzymes. Here, we report the cloning of an orphan nuclear receptor from chicken, termed chicken xenobiotic receptor (CXR), that is closely related to two mammalian xenobiotic-activated receptors, the pregnane X receptor (PXR) and the constitutive androstane receptor (CAR). Expression of CXR is restricted to tissues where drug induction of CYPs predominantly occurs, namely liver, kidney, small intestine, and colon. Furthermore, CXR binds to a previously identified phenobarbital-responsive enhancer unit (PBRU) in the 5'-flanking region of the chicken CYP2H1 gene. A variety of drugs, steroids, and chemicals activate CXR in CV-1 monkey cell transactivation assays. The same agents induce PBRU-dependent reporter gene expression and CYP2H1 transcription in a chicken hepatoma cell line. These results provide convincing evidence for a major role of CXR in the regulation of CYP2H1 and add a member to the family of xenobiotic-activated orphan nuclear receptors.

Daun, Jane M., Richard W. Ball, and Joseph G. Cannon. Glucocorticoid sensitivity of interleukin-1 agonist and antagonist secretion: the effects of age and gender. Am J Physiol Regulatory Integrative Comp Physiol 278: R855-R862, 2000.--Interleukin-1 (IL-1) is a primary mediator of inflammation that is regulated, in part, by the hypothalamic-pituitary-adrenal axis. The purpose of this study was to determine if gender- or age-related differences exist in the sensitivity of IL-1-producing cells to hydrocortisone. Peripheral blood mononuclear cells (PBMC) isolated from men and women (21-77 yr old) were incubated with hydrocortisone (0, 50, 100, 500, or 1,000 ng/ml) with or without lipopolysaccharide (LPS). Secretion of IL-1[Beta] and IL-1 receptor antagonist was inhibited in a dose-dependent manner (P = 0.001) without age- or gender-related differences. Hydrocortisone decreased soluble IL-1 receptor type II (sIL-1RII) secretion by unstimulated cells (P = 0.0001), but it increased secretion by LPS-stimulated cells (P = 0.0001) in all groups. Unstimulated cell supernatants from men contained greater concentrations of sIL-1RII than the supernatants from women (P = 0.011). Compared with men, PBMCs from women were less responsive to hydrocortisone inhibition of sIL-1RII secretion, regardless of age (P = 0.001), and compared with the follicular phase, sIL-1RII secretion was lower in the luteal phase of the menstrual cycle (P [is less than] 0.05). These data indicate that basal secretion and glucocorticoid modulation of sIL-1RII secretion by cultured PBMCs are gender dependent. Moreover, glucocorticoid influences on sIL-1RII secretion depend on the presence or absence of gram-negative bacterial toxins. interleukin-1[Beta]; soluble IL-1 receptor type II; IL-1 receptor antagonist; human mononuclear cells

Receptor-induced [Ca.sup.2+] signals comprise two interdependent components--rapid [Ca.sup.2+] release from [Ca.sup.2+] stores in the ER and [Ca.sup.2+] entry through slowly activating PM SOCs. The trigger for SOC activation is decreased [...], The coupling mechanism between endoplasmic reticulum (ER) calcium ion ([Ca.sup.2+]) stores and plasma membrane (PM) store-operated channels (SOCs) is crucial to [Ca.sup.2+] signaling but has eluded detection. SOCs may be functionally related to the TRP family of receptor-operated channels. Direct comparison of endogenous SOCs with stably expressed TRP3 channels in human embryonic kidney (HEK2933 cells revealed that TRP3 channels differ in being store independent. However, condensed cortical F-actin prevented activation of both SOC and TRP3 channels, which suggests that ER-PM interactions underlie coupling of both channels. A cell-permeant inhibitor of inositol trisphosphate receptor (Ins[P.sub.3]R) function, 2-aminoethoxydiphenyl borate, prevented both receptor-induced TRP3 activation and store-induced SOC activation. It is concluded that Ins[P.sub.3]Rs mediate both SOC and TRP channel opening and that the Ins[P.sub.3]R is essential for maintaining coupling between store emptying and physiological activation of SOCs.

There are three types of receptors that bind to antigens--B cell receptors (antibodies), T cell receptors (TCRs) expressed by αβ T cells, and TCRs expressed by γδT cells. The antigen-binding [...]