Cellular receptor for pixuna virus in chicken embryonic fibroblasts

In this study, we describe the isolation and partial characterization of a Pixuna virus receptor, which is a component of a plasma membrane fraction of chicken embryo fibroblast (CEF). Polyclonal antiserum was prepared from rabbits immunized with the membrane fraction. Said polyclonal antiserum reacted in a similar way as monoclonal antibodies raised against the membrane fraction. Both antisera were able to prevent CEF and Vero cells from infection with Pixuna virus. Immunofluorescence studies suggested that the receptors found in the fibroblasts and in the Vero cells shared at least some epitopes. The Western blot analysis of the purified membrane fraction antigens, which reacted with the monoclonal and polyclonal antibodies, detected a double band with a molecular mass of approximately 60 kDa. Not only immunofluorescence staining but also electron and immunoelectron microscopy studies evidenced the receptor localization in the plasma membrane. In this manner, we reported the isolation and partial characterization of a new Pixuna virus receptor in the plasma membrane of chicken embryo fibroblasts in culture. The data obtained demonstrated the receptor significance for the penetration of Pixuna virus into fibroblasts and mammalian cell and the related importance of designing new antiviral drugs by blocking the mechanism of receptor penetration of the virus into the cells.     

Ammonia-induced alterations in glutamate and muscimol binding to cerebellar synaptic membranes

Binding of glutamate and muscimol (an agonist for GABA_A receptors) to their respective receptors has been studied in the cerebellum of normal and hyperammonemic rats. There was a decrease in both high- and low-affinity binding of glutamate in the cerebellum during hyperammonemia. Kinetic studies revealed that the decrease is due to a reduction in the number of binding sites, but not due to changes in the binding affinities. Further studies also revealed that the decrease was only in the (NMDA)-specific binding sites without any alterations in the binding to non-NMDA sites represented by kianic acid (KA)- and quisqualic acid (QQ)-sensitive receptor sites. These effects were also mimicked when the membrane preparations from the cerebellum of normal animals were incubated with ammonium acetate. Enhancement of muscimol binding was observed in animals injected with ammonium acetate. It is concluded that hyperammonemic states, even in the presence of a functional liver, are capable of altering amino acid neurotransmission and this might play an important role in cerebral dysfunction under these conditions.     

IL-4 down-regulates IL-2 receptor p75 by accelerating its endocytosis

We examined the effects of interleukin 4 (IL-4) on the expressionof IL-2 receptor p75 (IL-2R p75) or ß chain on varioushuman T cells. IL-4 promptly down-regulated surface IL-2 receptor(IL-2R) p75 In these cells. Although IL-2-lnduced IL-2R p75down-regulation was seen more quickly, IL-2 did not contributeto the process of the IL-4-induced decrease of IL-2R p75. Northernblotting revealed that IL-4 did not reduce the expression ofIL-2R p75 mRNA. Studies using Pronase E, which digests cellsurface IL-2R p75, or brefeldin A, which blocks Intracytoplasmicprotein transport from endoplasmicretculum to the Golgi apparatus,suggest that IL-4-lnduced IL-2R p75 down-reguation is controlledafter IL-2R p75 is expressed on the cell surface. We found thatIL-4 accelerated the endocytosis of IL-2R p75, which was monitoredby (¹²⁵)||M||k-ß3 monocional antibody that recognizesnon-IL-2-bindlng epitope on IL-2R p75. These findings demonstratethat IL-4 down-regulates IL-2R p75 mainly by accelerating Itsendocytosis.     

Use of monoclonal antibody for assessment of estrogen and progesterone receptors in malignant effusions.

An immunocytochemical assay utilizing specific monoclonal antibodies against estrogen receptor (ER) and progesterone receptor (PgR) has been shown to be highly reliable for the detection of hormone receptors in hormone sensitive tumors. To assess the usefulness of this technique in malignant effusions, CytospinR (Shandon, Inc., Pittsburgh, PA 15275), preparations of 41 pleural and ascitic fluid were studied. The findings from the malignant cells employing estrogen and progesterone receptor immunocytochemical assay were compared with the results obtained from primary tumors by biochemical (dextran-coated charcoal) assay. The results agreed in 88% for ER and 83% for PgR. This study supports the potential value of cytochemical technique in detection of hormone receptors in malignant effusions. Assessment of hormone receptors in malignant effusions may be of clinical significance, particularly in situations where the hormone receptor status of the original tumor is not known. This information may also have some diagnostic and therapeutic importance in assessment of patients presenting with metastatic tumors of unknown origin.     

Identification of C-terminal domain residues involved in protein kinase A-mediated potentiation of kainate receptor subtype 6

Glutamate receptors are the major excitatory receptors in the vertebrate CNS and have been implicated in a number of physiological and pathological processes. Previous work has shown that glutamate receptor function may be modulated by protein kinase A (PKA)-mediated phosphorylation, although the molecular mechanism of this potentiation has remained unclear. We have investigated the phosphorylation of specific amino acid residues in the C-terminal cytoplasmic domain of the rat kainate receptor subtype 6 (GluR6) as a possible mechanism for regulation of receptor function. The C-terminal tail of rat GluR6 can be phosphorylated by PKA on serine residues as demonstrated using [gamma-32P]ATP kinase assays. Whole cell recordings of transiently transfected human embryonic kidney (HEK) 293 cells showed that phosphorylation by PKA potentiates whole cell currents in wildtype GluR6 and that removal of the cytoplasmic C-terminal domain abolishes this potentiation. This suggested that the C-terminal domain may contain residue(s) involved in the PKA-mediated potentiation. Single mutations of each serine residue in the C-terminal domain (S815A, S825A, S828A, and S837A) and a truncation after position 855, which removes all threonines (T856, T864, and T875) from the domain, do not abolish PKA potentiation. However, the S825A/S837A mutation, but no other double mutation, abolishes potentiation. These results demonstrate that phosphorylation of the C-terminal tail of GluR6 by PKA leads to potentiation of whole cell response, and the combination of S825 and S837 in the C-terminal domain is a vital component of the mechanism of GluR6 potentiation by PKA.     

Role of alpha chain-IL-2 complex in the formation of the ternary complex of IL-2 and high-affinity IL-2 receptor

Using anti-Tac (anti-alpha chain) and 2R-B (anti-beta chain) antibodies, we studied the roles of IL-2 receptor subunits (alpha and beta chains) in the formation of IL-2 and high-affinity IL-2 receptor complex, which is the initial event of IL-2 induced T cell growth. High-affinity IL-2 binding which was undetectable in the presence of 2R-B antibody at 4 degrees C became fully detectable when examined at 37 degrees C, which explained the lack of inhibition by 2R-B antibody of IL-2-induced proliferation of the cells expressing high-affinity IL-2 receptor. We further studied the mechanism of the 'reappearance' of high-affinity IL-2 binding in the presence of 2R-B antibody. The addition of IL-2 to the cells preincubated with radiolabeled or fluorescence-labeled 2R-B antibody resulted in a marked decrease in the antibody bound to the cells expressing high-affinity IL-2 receptor at 37 degrees C. This decrease was blocked by the presence of anti-Tac antibody, which inhibited IL-2 binding to alpha chain, but not by 7G7/B6 antibody, which recognized a non-IL-2 binding site of its chain. Furthermore, the decrease in cell-bound 2R-B antibody was not due to the internalization of beta chain-2R-B antibody complex, because the amount of cell-bound Mik-beta3 antibody recognizing a non-IL-2 binding epitope of beta chain remained unchanged, nor to the inhibition by simple competitive binding of IL-2 molecules to beta chain as judged from comparative studies of competitive binding inhibition. Taking these data together, the reappearance of high-affinity IL-2 binding was considered to be caused by the replacement of 2R-B antibody at the IL-2 binding site of beta chain by alpha chain-mediated IL-2, and it was strongly suggested that alpha chain-IL-2 complex has a key role in the formation of the ternary complex of IL-2 and high-affinity IL-2 receptor. alpha chain may function as a dimension converter of IL-2 to effectively deliver IL-2 molecules to a relatively small number of beta chains in the dynamics of the formation of high-affinity IL-2 binding in T cells.     

IL-1 up-regulates the expression of cytokine receptors on a factor-dependent human hemopoietic cell line, TF-1

A factor-dependent human hemopoietic cell line, TF-1, requiresinterleukln 3 (IL-3) or granulocyte/acrophage colony-stimulatingfactor (GM-CSF) for its long-term growth. We have found thatIL-4, IL-5, and IL-6 also support the growth of TF-1 and thatIL-1 enhances the proliferative effect of these cytoklnes. Augmentationby IL-1 is associated with up-regulatlon of the receptors forIL-3, IL-5, GM-CSF, and erythropoietln (Epo). IL-1 increasedthe number of binding sites forIL-3 and Epo without changingtheir affinities. In contrast, IL-1 Increased the number ofhigh affinity binding sites forGM-CSF and IL-5, whereas thetotal number of binding sites was unchanged. Chemical crossllnkingexperiments Indicated that the receptors for IL-3, IL-5, andGM-CSF were composed of two components and that the molecularmasses of the larger components of these cytokine receptorswere quite similar (120 kd). The enhanced expression of thelarger components of theIL-3, IL-5, and GM-CSF receptors byIL-1 may be responsible for IL-1-induced up-regulation of thesereceptors. These observations are consistent with the modelthat the receptors for IL-3 and GM-CSF share a common component.     

Human olfactory epithelial cells generated in vitro express diverse neuronal characteristics

The olfactory epithelium constitutes the sole source of regenerating neural cells that can be obtained from a living human. As such, primary cultures derived from human olfactory epithelial biopsies can be utilized to study neurobiological characteristics of individuals under different conditions and disease states. Here, using such human cultures, we report in vitro generation of cells that exhibit a complex neuronal phenotype, encompassing receptors and signaling pathways pertinent to both olfaction and other aspects of CNS function. Using in situ hybridization, we demonstrate for the first time the native expression of olfactory receptors in cultured cells derived from human olfactory epithelial tissue. We further establish the presence and function of olfactory transduction molecules in these cells using immunocytochemistry, calcium imaging and molecular methods. Western blot analysis revealed the expression of neurotransmitter receptors for dopamine (D2R), 5-HT (5HT2C) and NMDA subtypes 1 and 2A/2B. Stimulation with dopamine or 5-HT enhanced receptor G protein activation in a subtype specific manner, based on 35S-guanosine triphosphate incorporation assay. Functional characteristics of the cultured cells are demonstrated through enhanced tyrosine phosphorylation of NMDAR 2A/2B and recruitment of signaling partners in response to NMDA stimulation. The array of neuronal characteristics observed here establishes that proliferating cells derived from the human olfactory epithelium differentiate in vitro to express functional and molecular attributes of mature olfactory neurons. These cultured neural cells exhibit neurotransmitter pathways important in a number of neuropsychiatric disorders. Their ready availability from living humans thus provides a new tool to link functional and molecular features of neural cells with clinical characteristics of individual living patients.     

Toll-like receptors (TLRs) and Nod-like receptors (NLRs) in inflammatory disorders

Toll-like receptors (TLRs) and Nod-like receptors (NLRs) are two major forms of innate immune sensors, which provide immediate responses against pathogenic invasion or tissue injury. Activation of these sensors induces the recruitment of innate immune cells such as macrophages and neutrophils, initiates tissue repair processes, and results in adaptive immune activation. Abnormalities in any of these innate sensor-mediated processes may cause excessive inflammation due to either hyper responsive innate immune signaling or sustained compensatory adaptive immune activation. Recent gene association studies appear to reveal strong associations of NLR gene mutations and development of several idiopathic inflammatory disorders. In contrast, TLR polymorphisms are less often associated with inflammatory disorders. Nevertheless, TLRs are up-regulated in the affected tissue of most inflammatory disorders, suggesting TLR signaling is involved in the pathogenesis of chronic and/or idiopathic inflammatory disorders. NLR signaling results in the formation of a molecular scaffold complex (termed an inflammasome) and orchestrates with TLRs to induce IL-1β and IL-18, both of which are important mediators in the majority of inflammatory disorders. Therefore, understanding the roles of TLRs and NLRs in the pathogenesis of chronic and idiopathic inflammatory disorders may provide novel targets for the prevention and/or treatment of many common and uncommon diseases involving inflammation.     

病毒受体拮抗性诱获配体H9的体外活性及其对人趋化因子受体CX3CR1的作用

目的:来源于US28受体N末端的诱惑配体多肽H9,以阐明H9的体外活性及其对细胞表面趋化因子受体CX3CR1内化及调变研究,探讨H9对人趋化因子受体CX3CR1的作用及影响。方法:立足US28的广谱趋化因子结合活性,得到趋化因子受体拮抗性多肽H9。采用趋化抑制实验检测多肽对生理性趋化因子引起的细胞迁移活性的影响,流式细胞术方法(FCM)检测细胞内钙离子浓度变化,利用激光共聚焦显微镜和流式细胞仪分别定性、定量检测CX3CR1的内化,以阐明H9的生物活性及其对人源受体CX3CR1的作用及其机制。结果:多肽H9可以阻断受体结合生理性趋化因子形成的趋化作用,本身不引起趋化运动,不影响胞内信号转导和细胞自然活性;200 ng/mL H9在给药后的最初50min钟内能使细胞表面受体CX3CR1内化达到最大值,内化率约为70%,第100分钟,内化到细胞内的CX3CR1逐渐再循环到细胞表面。证明了H9能引起细胞表面受体CX3CR1内化,内化的受体部分再循环到细胞表面。结论:H9是一种趋化因子受体抑制短肽,影响人受体CX3CR1的内化,但内化后受体再循环到细胞表面,对人受体CX3CR1生理功能没有明显影响,可以作为特异性抗病毒多肽。     

ER、PR及其相应拮抗剂与甲状腺癌的相关性研究进展

雌激素受体(ER)、孕激素受体(PR)在甲状腺癌中的异常表达说明性激素受体在甲状腺癌的发病机制中起重要作用.ER、PR通过经典的基因途径及非基因途径对甲状腺癌的发生、发展及生物学特征产生重要影响.性激素受体拮抗剂抑制甲状腺癌细胞增殖作用的研究,将为甲状腺癌的治疗提供新的选择方案.     

Changes in gonadal steroid receptors in the cardinal ligaments of prolapsed uteri: immunohistomorphometric data

BACKGROUND:The precise mechanism of uterine prolapse is poorly understood. This immunohistochemical study was performed on paraffin-embedded sections of the cardinal ligaments in an attempt to evaluate the differential expression of gonadal steroid receptors in human cardinal ligaments of prolapsed uteri compared with non-prolapsed controls. METHODS: Specimens from women with pelvic organ prolapse (POP) stage III (n = 33), together with the appropriate controls (n = 25), were stained for estrogen receptor alpha (ERalpha), ERbeta, progesterone receptor (PR), androgen receptor (AR) and Ki-67. The control materials were samples of the cardinal ligaments obtained from pre- and post-menopausal women with no prolapse, who were not using hormonal therapy. RESULTS The prolapsed ligaments expressed 1.5-2.5 times more ERalpha-positive cells (statistically significant in post-menopausal women not taking HRT, P < 0.001), a 3-4 times greater percentage of AR-positive cells (P = 0.004 and P = 0.008 in pre-menopausal and post-menopausal women not taking HRT, respectively) and twice the percentage of PR-positive cells (statistically significant in the pre-menopausal group, P = 0.03) compared with the no prolapse group. Expression of ERbeta was twice as high in the ligaments of pre-menopausal women with no prolapse compared with those with prolapse (P = 0.02), and no significant difference was found in the post-menopausal groups. The use of HRT was significantly associated with low AR and high PR expression. Ki-67 expression was not detected in these specimens. CONCLUSIONS: The clearly discernible levels of expression of ERalpha, ERbeta, AR and PR in the prolapsed cardinal ligaments may suggest a relationship to the process of tissue stretch 'trauma', rather than an effect of the menopausal status, HRT use or cell proliferation. The use of HRT in post-menopausal women appears to offset some of the changes observed with the prolapse.     

The biochemistry,signalling and disease relevance of RYK and other WNT-binding receptor tyrosine kinases

The receptor tyrosine kinases (RTKs) are a well-characterized family of growth factor receptors that have central roles in human disease and are frequently therapeutically targeted. The RYK, ROR, PTK7 and MuSK subfamilies make up an understudied subset of WNT-binding RTKs. Numerous developmental, stem cell and pathological roles of WNTs, in particular WNT5A, involve signalling via these WNT receptors. The WNT-binding RTKs have highly context-dependent signalling outputs and stimulate the β-catenin-dependent, planar cell polarity and/or WNT/Ca²⁺ pathways. RYK, ROR and PTK7 members have a pseudokinase domain in their intracellular regions. Alternative signalling mechanisms, including proteolytic cleavage and protein scaffolding functions, have been identified for these receptors. This review explores the structure, signalling, physiological and pathological roles of RYK, with particular attention paid to cancer and the possibility of therapeutically targeting RYK. The other WNT-binding RTKs are compared with RYK throughout to highlight the similarities and differences within this subset of WNT receptors.     

Expression of androgen receptors in benign and malignant endometrial stromal neoplasms

Several studies have shown that endometrial stromal neoplasms express estrogen and progesterone receptors (ER, PR). To our knowledge, the presence or absence of androgen receptors (AR) in these rare uterine neoplasms has not been investigated. Tumors (n=20)—3 endometrial stromal nodules, 14 low-grade endometrial stromal sarcomas (ESS, low grade), and 3 high-grade endometrial sarcomas (undifferentiated endometrial sarcoma, UES)—were studied. Immunohistochemical analyses for ER, PR, and AR were performed on formalin-fixed, paraffin-embedded archival material. Positive immunoreactions for ER and PR were observed in 14 (70%) and 17 (85%) cases, respectively. Furthermore, 9 cases (45%) were positive for AR. Among 17 ESS and UES cases, 7 (41%) revealed positivity for AR. Two of three benign stromal nodules were also positive for AR. Moreover, one of the three high-grade sarcomas (undifferentiated endometrial sarcoma) was negative for both ER and PR, but showed positive reaction for AR. In summary, ARs are expressed in 45% of endometrial stromal neoplasms. In addition to determination of ER and PR, the results of immunohistochemical examination of AR in these rare uterine tumors may have some impact on the postoperative management of the patients.     

Histological and immunohistochemical study of estrogen and progesterone receptors in normal human breast tissue in adult age groups vulnerable to malignancy

Analysis of receptor status has become standard procedure for assessing breast cancer patients. Estrogen causes epithelial proliferation in breast tissue via the estrogen receptor (ER). The progesterone receptor (PR) is also regulated by the estrogen gene. Analyzing ER and PR together gives information regarding the likely response of carcinoma patients to hormonal therapy. The aim of the present study was to record the expression patterns of ER and PR in normal mammary tissue in different age groups to provide reference data to facilitate histological diagnosis. Breast tissues from the upper outer quadrant of each side of 27 adult female cadavers were examined after H & E staining. ER and PR were identified and examined by immunohistochemistry. The percentage area occupied by parenchyma relative to stromal tissue was calculated in different age groups and was about 4:6, 3.5:6.5, 3:7, 2:8, and 1.5:8.5 in the 3rd, 4th and 5th, 6th, 7th, 8th and 9th, and 10th decades of life, respectively. Both ER and PR were present in all age groups and the numbers of both receptors were maximal during the 4th decade. The distribution and staining patterns for both ER and PR were recorded in different age groups. The contiguous pattern of ER, which is considered pathognomonic of breast carcinoma, was not seen except in one case in the 6th decade. Moderately stained ER and PR receptor sites predominated throughout. The study of normal breast tissue of similar age might provide comparisons that will help histopathologists to make clinical diagnoses from breast biopsies. Clin. Anat. 29:729–737, 2016. © 2016 Wiley Periodicals, Inc.     

Differential effects of epidermal growth factor (EGF) receptor ligands on receptor binding,downstream signalling pathways and DNA synthesis in hepatocytes

Hepatocytes are responsive to mitogenic effects of several ligands acting via EGFR. Studying primary cultures of rat hepatocytes, we found that, as compared to EGF, HB-EGF had a markedly higher affinity of the EGFR, while AR and TGFα had lower affinity. HB-EGF was also more potent compared to the other growth factors regarding phosphorylation of EGFR, Shc, ERK1/2 and Akt. All ligands induced phosphorylation of ErbB2, indicating receptor heterodimerization. TGFα, despite having much lower receptor affinity, was about equally potent and efficacious as HB-EGF as a stimulator of DNA synthesis. In contrast, EGF had relatively high affinity but markedly lower efficacy in stimulation of DNA synthesis. The results suggest that amplifying and/or inhibitory mechanisms may modulate the mitogenic responses downstream of the initial signalling steps, and that this may affect the effects of the EGFR ligands differentially.     

Opposing roles of glucocorticoid receptor and mineralocorticoid receptor in trimethyltin-induced cytotoxicity in the mouse hippocampus

The organotin trimethyltin (TMT) is known to cause neuronal degeneration in the murine brain. Earlier studies indicate that TMT-induced neuronal degeneration is enhanced by adrenalectomy and prevented by exogenous glucocorticoid. The aim of this study was to investigate the regulation of TMT neuroxicity by corticosterone receptors including type I (mineralocorticoid receptor, MR) and type II (glucocorticoid receptor, GR) in adult mice. The systemic injection of TMT at the dose of 2.0 or 2.8 mg/kg produced a marked elevation in the level of plasma corticosterone that was both dose and time dependent. The MR agonist aldosterone had the ability to exacerbate TMT cytotoxicity in the dentate granule cell layer, whereas its antagonist spironolactone protected neurons from TMT cytotoxicity there. In contrast, the GR antagonist mifepristone exacerbated the TMT cytotoxicity. Taken together, our data suggest TMT cytotoxicity is oppositely regulated by GR and MR signals, being exacerbated by MR activation in adult mice.     

Pseudo-high-affinity IL-2 receptor and growth signal transduction in lymphocytes

We examined whether the psuedo-hlgh-affinity IL-2 receptor (IL-2R)could transduce a growth signal in lymphocytes. Since lymphocytesdevoid of the I chain were not available, we employed functionaldepletion of the I chain from a mouse T cell line CTLL-2 transfectedwith cDNA for the human H chain and its defective mutants whichcan bind IL-2 but cannot transduce a growth signal. The numbersof human H, mouse I, and mouse H chains expressed in these transfectantswere similar to each other. When the human H chain (and mutants)-expressing CTLL-2 transfectants were incubated with 300 pMhuman IL-2, the majority of human H and mouse I chains togetherwith the L chain formed the hlgh-affinity receptor complex whereasthe majority of mouse H chains remained free. When the humanH chain mutant-expressing CTLL-2 transfectants were incubatedwith 300 pM human IL-2, the I chain was expected to be functionallydepleted by the formation of the inactive high-affinity complexwith the inactive human H chain mutants. However, the humanH chain mutant-expressing CTLL-2 transfectants proliferatedwith a half maximal response to human IL-2 at 300–500pM which agrees with the pseudo-high affinity K_d value displayedby the mouse L and H chains. The human H chain-expressing transfectantsproliferated in response the human IL-2 in a similar kineticswith CTLL-2. CTLL-2 and the human H chaln/mutants-transfectantsall responded to mouse IL-2 in the same kinetics. The maximalresponses of each cell line to mouse and human IL-2 were similar.These results suggest that the pseudo-hlgh-affinity IL-2R composedof the L and H chains may transduce a growth signal, and thata molecule other than the I chain may be involved in proliferativesignal transduction.