bluuebunny/crossref_metadata_2025 huggingface dataset:
Disruption of the Glucocorticoid Receptor Assembly with Heat Shock Protein 90 by a Peptidic Antiglucocorticoid
Authors: Dao-Phan Hai-Pascal , Formstecher Pierre , Lefebvre Philippe
Published: January 2014

Association of glucocorticoid (GR) and progesterone (PR) receptors with a set of molecular chaperones, including the 90-kDa heat shock protein (hsp90), is a dynamic process required for proper folding and maintaining these nuclear receptors under a transcriptionally inactive, ligand-responsive state. Mutational studies of the chicken hsp90 complementary DNA suggested that three regions of this protein (A, B, and Z) interact with the hormone-binding domain of GR, whereas region A is dispensable for hsp90 binding to PR. We found that this 69-amino acid region can be narrowed down to a 35-mer α-helical, acidic peptide, which is by itself able to inhibit hsp90 association to GR translated in vitro. The hsp90-free GR did not bind ligand, but was devoid of any specific DNA-binding activity, and higher peptide concentrations specifically inhibited the binding of activated GR to DNA. When overexpressed in cultured cells, this peptide acted as an antiglucocorticoid and inhibited the antiactivating protein-1 activity and the ligand-dependent nuclear transfer of GR. None of these effects, either in vivo and in vitro, was observed for PR. The region from residue 232 to residue 265 of hsp90 is, therefore, a domain critical for its association to GR, an association that is a prerequisite for receptor transcriptional activity. More importantly, these results demonstrate that targeting specific protein/protein interaction interfaces is a powerful means to specifically modulate nuclear receptor signaling pathways in a ligand-independent manner.
Inhibition of Gonadotropin-Releasing Hormone Receptor Signaling by Expression of a Splice Variant of the Human Receptor
Authors: Grosse Robert , Schöneberg Torsten , Schultz Günter , Gudermann Thomas
Published: January 2014

GnRH binds to a specific G protein-coupled receptor in the pituitary to regulate synthesis and secretion of gonadotropins. Using RT-PCR and human pituitary poly(A)+ RNA as a template, the full-length GnRH receptor (wild type) and a second truncated cDNA characterized by a 128-bp deletion between nucleotide positions 522 and 651 were cloned. The deletion causes a frame shift in the open reading frame, thus generating new coding sequence for further 75 amino acids. The truncated cDNA arises from alternative splicing by accepting a cryptic splicing acceptor site in exon 2. Distinct translation products of approximately 45–50 and 42 kDa were immunoprecipitated from COS-7 cells transfected with cDNA coding for wild type GnRH receptor and the truncated splice variant, respectively. Immunocytochemical and enzyme-linked immunosorbent assay studies revealed a membranous expression pattern for both receptor isoforms. Expression of the splice variant, however, occurred at a significantly lower cell surface receptor density. In terms of ligand binding and phospholipase C activation, the wild type receptor showed characteristics of a typical GnRH receptor, whereas the splice variant was incapable of ligand binding and signal transduction. Coexpression of wild type and truncated proteins in transiently or stably transfected cells, however, resulted in impaired signaling via the wild type receptor by reducing maximal agonist-induced inositol phosphate accumulation. The inhibitory effect depended on the amount of splice variant cDNA cotransfected and was specific for the GnRH receptor because signaling via other Gq/11-coupled receptors, such as the thromboxane A2, M5 muscarinic, and V1 vasopressin receptors, was not affected. Immunological studies revealed that coexpression of the wild type receptor and the truncated splice variant resulted in impaired insertion of the wild type receptor into the plasma membrane. Thus, expression of truncated receptor proteins may highlight a novel principle of specific functional inhibition of G protein-coupled receptors.
Shc Phosphotyrosine-Binding Domain Dominantly Interacts with Epidermal Growth Factor Receptors and Mediates Ras Activation in Intact Cells
Authors: Sakaguchi Kazuhiko , Okabayashi Yoshinori , Kido Yoshiaki , Kimura Sachiko , Matsumura Yoko , Inushima Koichi , Kasuga Masato
Published: January 2014

The adaptor protein Shc contains a phosphotyrosine binding (PTB) domain and a Src homology 2 (SH2) domain, both of which are known to interact with phosphorylated tyrosines. We have shown previously that tyrosine 1148 of the activated epidermal growth factor (EGF) receptor is a major binding site for Shc while tyrosine 1173 is a secondary binding site in intact cells. In the present study, we investigated the interaction between the PTB and SH2 domains of Shc and the activated human EGF receptor. Mutant 52-kDa Shc with an arginine-to-lysine substitution at residue 175 in the PTB domain (Shc R175K) or 397 in the SH2 domain (Shc R397K) was coexpressed in Chinese hamster ovary cells overexpressing the wild-type or mutant EGF receptors that retained only one of the autophosphorylation sites at tyrosine 1148 (QM1148) or 1173 (QM1173). Shc R397K was coprecipitated with the QM1148 and QM1173 receptors, was tyrosine-phosphorylated, and associated with Grb2 and Sos. In contrast, coprecipitation of Shc R175K with the mutant receptors was barely detectable. In cells expressing the QM1173 receptor, Shc R175K was tyrosine-phosphorylated and associated with Grb2, while association of Sos was barely detectable. In cells expressing the QM1148 receptor, tyrosine phosphorylation of Shc R175K was markedly reduced. When both Shc R175K and 46-kDa Shc R397K were coexpressed with the mutant receptors, p46 Shc R397K was dominantly tyrosine-phosphorylated. In cells expressing the wild-type receptor, Shc R397K, but not Shc R175K, translocated to the membrane in an EGF-dependent manner. In addition, Ras activity stimulated by the immunoprecipitates of Shc R397K was significantly higher than that by the immunoprecipitates of Shc R175K. The present results indicate that tyrosine 1148 of the activated EGF receptor mainly interacts with the Shc PTB domain in intact cells. Tyrosine 1173 interacts with both the PTB and SH2 domains, although the interaction with the PTB domain is dominant. In addition, Shc bound to the activated EGF receptor via the PTB domain dominantly interacts with Grb2-Sos complex and plays a major role in the Ras-signaling pathway.
The Carboxyl-Terminal Region Is a Determinant for the Intracellular Behavior of the Chorionic Gonadotropin β Subunit: Effects on the Processing of the Asn-Linked Oligosaccharides
Authors: Muyan Mesut , Boime Irving
Published: January 2014

The placental hormone human CG (hCG) consists of two noncovalently linked α- and β-subunits similar to the other glycoprotein hormones LH, FSH, and TSH. These heterodimers share a common α subunit but differ in their structurally distinct β subunits. The CGβ subunit is distinguished among the β subunits by the presence of a C-terminal extension with four serine-linked oligosaccharides (carboxyl terminal peptide or CTP). In previous studies we observed that deleting this sequence decreased assembly of the truncated CGβ subunit (CGβ114) with the α-subunit and increased the heterogeneity of the secreted forms of the uncombined subunit synthesized in transfected Chinese hamster ovary (CHO) cells. The latter result was attributed to alterations in the processing of the two N-linked oligosaccharides. To examine at what step this heterogeneity occurs, the CGβ and CGβ114 genes were transfected into wild-type and mutant CHO cell lines that are defective in the late steps of the N-linked carbohydrate-processing pathway. We show here that removal of the CTP alters the processing of the core mannosyl unit of the subunit to complex forms at both glycosylation sites and that the oligosaccharides contain polylactosamine. Although it has been presumed that there is little intramolecular interaction between the CTP and the proximal domains of the subunit, our data suggest that the CTP sequence participates in the folding of the newly synthesized subunit, which is manifest by the posttranslational changes observed here.
Determination of Gab1 (Grb2-Associated Binder-1) Interaction with Insulin Receptor-Signaling Molecules
Authors: Rocchi Stéphane , Tartare-Deckert Sophie , Murdaca Joseph , Holgado-Madruga Marina , Wong Albert J. , Van Obberghen Emmanuel
Published: January 2014

The newly identified insulin receptor (IR) substrate, Gab1 [growth factor receptor bound 2 (Grb2)-associated binder-1] is rapidly phosphorylated on several tyrosine residues by the activated IR. Phosphorylated Gab1 acts as a docking protein for Src homology-2 (SH2) domain-containing proteins. These include the regulatory subunit p85 of phosphatidylinositol 3-kinase and phosphotyrosine phosphatase, SHP-2. In this report, using a modified version of the yeast two-hybrid system, we localized which Gab1 phospho-tyrosine residues are required for its interaction with phosphatidylinositol 3-kinase and with SHP-2. Our results demonstrate that to interact with p85 or SHP-2 SH2 domains, Gab1 must be tyrosine phosphorylated by IR. Further, we found that Gab1 tyrosine 472 is the major site for association with p85, while tyrosines 447 and 589 are participating in this process. Concerning Gab1/SHP-2 interaction, only mutation of tyrosine 627 prevents binding of Gab1 to SHP-2 SH2 domains, suggesting the occurrence of a monovalent binding event. Finally, we examined the role of Gab1 PH (Pleckstrin homology) domain in Gab1/IR interaction and in Gab1 tyrosine phosphorylation by IR. Using the modified two-hybrid system and in vitro experiments, we found that the Gab1 PH domain is not important for IR/Gab1 interaction and for Gab1 tyrosine phosphorylation. In contrast, in intact mammalian cells, Gab1 PH domain appears to be crucial for its tyrosine phosphorylation and association with SHP-2 after insulin stimulation.
Somatostatin Activation of Mitogen-Activated Protein Kinase via Somatostatin Receptor 1 (SSTR1)
Authors: Florio Tullio , Yao Hong , Carey Kendall D. , Dillon Tara J. , Stork Philip J. S.
Published: January 2014

Hormones and growth factors regulate cell growth via the mitogen-activated protein (MAP) kinase cascade. Here we examine the actions of the hormone somatostatin on the MAP kinase cascade through one of its two major receptor subtypes, the somatostatin receptor 1 (SSTR1) stably expressed in CHO-K1 cells. Somatostatin antagonizes the proliferative effects of fibroblast growth factor in CHO-SSTR1 cells via the SSTR1 receptor. However, in these cells, somatostatin robustly activates MAP kinase (also called extracellular signal regulated kinase; ERK) and augments fibroblast growth factor-stimulated ERK activity. We show that the activation of ERK via SSTR1 is pertussis toxin sensitive and requires the small G protein Ras, phosphatidylinositol 3-kinase, the serine/threonine kinase Raf-1, and the protein tyrosine phosphatase SHP-2. The activation of ERK by SSTR1 increased the expression of the cyclin-dependent protein kinase inhibitor p21cip1/WAF1. Previous studies have suggested that somatostatin-stimulated protein tyrosine phosphatase activity mediates the growth effects of somatostatin. Our data suggest that SHP-2 stimulation by SSTR1 may mediate some of these effects through the activation of the MAP kinase cascade and the expression of p21cip1/WAF1.
Functional Analysis of a Novel Estrogen Receptor-β Isoform
Authors: Hanstein Bettina , Liu Hong , Yancisin Molly C. , Brown Myles
Published: January 2014

A new level of complexity has recently been added to estrogen signaling with the identification of a second estrogen receptor, ERβ. By screening a rat prostate cDNA library, we detected ERβ as well as a novel isoform that we termed ERβ2. ERβ2 contains an in-frame inserted exon of 54 nucleotides that results in the predicted insertion of 18 amino acids within the ERβ hormone-binding domain. We also have evidence for the expression of both ERβ1 and ERβ2 in human cell lines. Competition ligand binding analysis of bacterially expressed fusion proteins revealed an 8-fold lower affinity of ERβ2 for 17β-estradiol (E2)[ dissociation constant (Kd ∼ 8 nm)] as compared with ERβ1 (Kd ∼ 1 nm). In vitro transcribed and translated ERβ1 and ERβ2 bind specifically to a consensus estrogen responsive element in a gel mobility shift assay. Furthermore, we show heterodimerization of ERβ1 and ERβ2 with each other as well as with ERα. In affinity interaction assays for proteins that associate specifically with the hormone-binding domain of these receptors, we demonstrate that the steroid receptor coactivator SRC-1 interacts in an estrogen-dependent manner with ERα and ERβ1, but not with ERβ2. In cotransfection experiments with expression plasmids for ERα, ERβ1, and ERβ2 and an estrogen-responsive element-containing luciferase reporter, the dose response of ERβ1 to E2 was similar to that of ERα although the maximal stimulation was approximately 50%. In contrast, ERβ2 required 100- to 1000-fold greater E2 concentrations for maximal activation. Thus, ERβ2 adds yet another facet to the possible cellular responses to estrogen.
A Fusion Protein of the Estrogen Receptor (ER) and Nuclear Receptor Corepressor (NCoR) Strongly Inhibits Estrogen-Dependent Responses in Breast Cancer Cells
Authors: Chien Pei-Yu , Ito Masafumi , Park Youngkyu , Tagami Tetsuya , Gehm Barry D. , Jameson J. Larry
Published: January 2014

Nuclear receptor corepressor (NCoR) mediates repression (silencing) of basal gene transcription by nuclear receptors for thyroid hormone and retinoic acid. The goal of this study was to create novel estrogen receptor (ER) mutants by fusing transferable repressor domains from the N-terminal region of NCoR to a functional ER fragment. Three chimeric NCoR-ER proteins were created and shown to lack transcriptional activity. These fusion proteins silenced basal transcription of the ERE2-tk-Luc reporter gene and inhibited the activity of cotransfected wild-type ER (wtER), indicating that they possess dominant negative activity. One of the fusion proteins (CDE-RD1), containing the ER DNA-binding and ligand-binding domains linked to the NCoR repressor domain (RD1), was selected for detailed examination. Its hormone affinity, intracellular localization, and level of expression in transfected cells were similar to wtER, and it bound to the estrogen response element (ERE) DNA in gel shift assays. Glutathione-S-transferase pull-down assays showed that CDE-RD1 retains the ability to bind to steroid receptor coactivator-1. Introduction of a DNA-binding domain mutation into the CDE-RD1 fusion protein eliminated silencing and dominant negative activity. Thus, the RD1 repressor domain prevents transcriptional activation despite the apparent ability of CDE-RD1 to bind DNA, ligand, and coactivators. Transcriptional silencing was incompletely reversed by trichostatin A, suggesting a histone deacetylase-independent mechanism for repression. CDE-RD1 inhibited ER-mediated transcription in T47D and MDA-MB-231 breast cancer cells and repressed the growth of T47D cells when delivered to the cells by a retroviral vector. These ER-NCoR fusion proteins provide a novel means for inhibiting ER-mediated cellular responses, and analogous strategies could be used to create dominant negative mutants of other transcription factors.
Alternative Splicing of Vascular Endothelial Growth Factor (VEGF)-R1 (FLT-1) pre-mRNA Is Important for the Regulation of VEGF Activity
Authors: He Yulong , Smith Stephen K. , Day Kate A. , Clark Dawn E. , Licence Diana R. , Charnock-Jones D. Stephen
Published: January 2014

Angiogenesis is essential for normal mammalian development and is controlled by the local balance of pro- and antiangiogenic factors. Here we describe a novel mouse cDNA sequence encoding sFLT-1 that is a potent antagonist to vascular endothelial growth factor (VEGF) and show for the first time its in vivo production. In situ hybridization and Northern blot analysis with probes specific for sFLT-1 or FLT-1 showed that the relative abundance of their mRNAs changed markedly in spongiotrophoblast cells in the placenta as gestation progressed. On day 11 of pregnancy, sFLT-1 mRNA was undetectable but FLT-1 readily apparent, and by day 17 sFLT-1 mRNA was abundant but FLT-1 barely detectable. sFLT-1 was identified in conditioned medium of cultured placenta from day 17 pregnant mice and likely to be present in the circulation, as there is a substantial increase of VEGF-binding activity in the serum from day 13 of pregnancy, which coincides with the abundant sFLT-1 expression in placenta. Expression of sFLT-1 was also observed in adult lung, kidney, liver, and uterus. These data suggest a novel mechanism of regulation of angiogenesis by alternative splicing of FLT-1 pre-mRNA. Treatment of pregnant mice with exogenous VEGF from day 9 to 17 of pregnancy, which alters the ratio of VEGF to sFLT-1, resulted in an increase in the number of resorption sites and fibrin deposition in the placenta of ongoing pregnancies. These findings have important implications for understanding placental function and may be relevant in a range of disease states.
Transcriptional Activities of the Orphan Nuclear Receptor ERRα (Estrogen Receptor-Related Receptor-α)
Authors: Vanacker Jean-Marc , Bonnelye Edith , Chopin-Delannoy Sandrine , Delmarre Cateline , Cavaillès Vincent , Laudet Vincent
Published: January 2014

Estrogen receptor-related receptor α (ERRα) is an orphan nuclear receptor closely related to the estrogen receptor (ER), whose expression covers various stages of embryonic development and persists in certain adult tissues. We show that ERRα binds as a homodimer on a specific target sequence, the SFRE (SF-1 response element), already known to respond to the orphan nuclear receptor SF-1. Target sequences that are related to the SFRE and that discriminate between ERRα and SF-1 were identified. We have also analyzed the transcriptional properties of the ERRα originating from various species. All ERRα orthologs act as potent transactivators through the consensus SFRE. ERRα activity depends on the putative AF2AD domain, as well as on a serum compound that is withdrawn by charcoal treatment, suggesting the existence of a critical regulating factor brought by serum.
Estradiol Suppresses Phosphorylation of Cyclic Adenosine 3′,5′-Monophosphate Response Element Binding Protein (CREB) in the Pituitary: Evidence for Indirect Action via Gonadotropin-Releasing Hormone
Authors: Duan W. Rachel , Shin Jennifer L. , Jameson J. Larry
Published: January 2014

Estradiol acts on the hypothalamus and pituitary gland to modulate the synthesis and secretion of gonadotropins. We recently reported that GnRH-induced transcription of the human gonadotropin α-gene promoter is increased markedly in transfected pituitary cells derived from animals treated with estradiol. Because the cAMP response element binding (CREB) protein plays an important role in the transcriptional regulation of this promoter and is highly regulated by posttranslational phosphorylation, we hypothesized that it might serve as a target for estradiol-induced sensitivity to GnRH. In this study, we assessed the roles of estradiol and GnRH in the regulation of CREB phosphorylation in the rat pituitary. Using an antibody that specifically recognizes phosphorylated CREB (pCREB), we found that the pituitary content of pCREB was inversely related to the level of estradiol during the estrous cycle. Ovariectomy increased the level of pCREB, and treatment with estradiol for 10 days decreased the content of pCREB dramatically (93% inhibition). A similar reduction of pCREB was seen when ovariectomized rats were treated with a GnRH receptor antagonist for 10 days. This result indicates that the ovariectomy-induced increase in pCREB is GnRH-dependent. In αT3 gonadotrope cells, estradiol had no direct effect on CREB phosphorylation, whereas GnRH increased CREB phosphorylation 4- to 5-fold within 5 min. We conclude that estradiol inhibits CREB phosphorylation in the gonadotrope, probably by inhibiting GnRH production. The estradiol-induced decrease in CREB phosphorylation is proposed to lower basalα -promoter activity and increase its responsiveness to GnRH. (Molecular Endocrinology 13: 1338–1352, 1999)
Synergistic Activation of the Inhibin α-Promoter by Steroidogenic Factor-1 and Cyclic Adenosine 3′,5′-Monophosphate
Authors: Ito Masafumi , Park Youngkyu , Weck Jennifer , Mayo Kelly E. , Jameson J. Larry
Published: January 2014

The inhibin α-subunit gene is expressed in the ovary, testis, adrenal, and pituitary. Because this pattern of expression corresponds to that of the orphan nuclear receptor, steroidogenic factor-1 (SF-1), we hypothesized that the inhibin α promoter might be regulated by SF-1. Expression of exogenous SF-1, in an SF-1 deficient cell line, caused modest stimulation of the inhibinα promoter. However, activation of the cAMP pathway, which is known to regulate inhibin α expression, greatly enhanced the actions of SF-1. Coexpression of SF-1 with the catalytic subunit of cAMP-dependent protein kinase A caused greater than 250-fold stimulation, whereas only 4- or 7-fold stimulation was seen by the SF-1 or protein kinase A pathway alone. Synergistic stimulation by SF-1 and the cAMP pathway was also seen in GRMO2 granulosa cells, which express endogenous SF-1. Deletion and site-directed mutagenesis localized a novel SF-1 regulatory element (TCA GGGCCA; −137 to −129) adjacent to a variant cAMP-response element (CRE; −120 to −114). The synergistic property of SF-1 and cAMP stimulation was inherent within this composite inhibin α fragment (−146 and −112), as it was transferable to heterologous promoters. Mutations in either the CRE or the SF-1 regulatory element completely eliminated synergistic activation by these pathways. The binding of SF-1 and CRE binding protein (CREB) to the inhibin α regulatory elements was relatively weak in gel mobility shift assays, consistent with their deviation from consensus binding sites. However, SF-1 was found to interact with CREB using an assay in which epitope-tagged SF-1 was expressed in cells and used to pull down in vitro translated CREB. Expression of CREB binding protein (CBP), a coactivator that interacts with SF-1 and CREB, further enhanced transcription by these pathways. Stimulation by the SF-1 and cAMP pathways was associated with increased histone H4 acetylation, suggesting that chromatin remodeling accompanies their actions. We propose a model in which direct interactions of SF-1, CREB, and associated coactivators like CBP induce strongly cooperative transactivation by pathways that individually have relatively weak effects on transcription.
Chronic Elevation of Calmodulin in the Ventricles of Transgenic Mice Increases the Autonomous Activity of Calmodulin-Dependent Protein Kinase II, Which Regulates Atrial Natriuretic Factor Gene Expression
Authors: Colomer Josep M. , Means Anthony R.
Published: January 2014

Although isoforms of Ca2+/calmodulin-dependent protein kinase II (CaMKII) have been implicated in the regulation of gene expression in cultured cells, this issue has yet to be addressed in vivo. We report that the overexpression of calmodulin in ventricular myocytes of transgenic mice results in an increase in the Ca2+/calmodulin-independent activity of endogenous CaMKII. The calmodulin transgene is regulated by a 500-bp fragment of the atrial natriuretic factor (ANF) gene promoter which, based on cell transfection studies, is itself known to be regulated by CaMKII. The increased autonomous activity of CaMKII maintains the activity of the transgene and establishes a positive feedforward loop, which also extends the temporal expression of the endogenous ANF promoter in ventricular myocytes. Both the increased activity of CaMKII and transcriptional activation of ANF are highly selective responses to the chronic overexpression of calmodulin. These results indicate that CaMKII can regulate gene expression in vivo and suggest that this enzyme may represent the Ca2+-dependent target responsible for reactivation of the ANF gene during ventricular hypertrophy.
Hepatic Nuclear Factor-3 (HNF-3 or Foxa2) Regulates Glucagon Gene Transcription by Binding to the G1 and G2 Promoter Elements
Authors: Gauthier Benoit R. , Schwitzgebel Valerie M. , Zaiko Maia , Mamin Aline , Ritz-Laser Beate , Philippe Jacques
Published: January 2014

Glucagon gene expression in the endocrine pancreas is controlled by three islet-specific elements (G3, G2, and G4) and theα -cell-specific element G1. Two proteins interacting with G1 have previously been identified as Pax6 and Cdx2/3. We identify here the third yet uncharacterized complex on G1 as hepatocyte nuclear factor 3 (HNF-3)β, a member of the HNF-3/forkhead transcription family, which plays an important role in the development of endoderm-related organs. HNF-3 has been previously demonstrated to interact with the G2 element and to be crucial for glucagon gene expression; we thus define a second binding site for this transcription on the glucagon gene promoter. We demonstrate that both HNF-3α and -β produced in heterologous cells can interact with similar affinities to either the G1 or G2 element. Pax6, which binds to an overlapping site on G1, exhibited a greater affinity as compared with HNF-3α or -β. We show that both HNF-3β and -α can transactivate glucagon gene transcription through the G2 and G1 elements. However, HNF-3 via its transactivating domains specifically impaired Pax6-mediated transactivation of the glucagon promoter but had no effect on transactivation by Cdx2/3. We suggest that HNF-3 may play a dual role on glucagon gene transcription by 1) inhibiting the transactivation potential of Pax6 on the G1 and G3 elements and 2) direct activation through G1 and G2.
Estrogen Action Via the G Protein-Coupled Receptor, GPR30: Stimulation of Adenylyl Cyclase and cAMP-Mediated Attenuation of the Epidermal Growth Factor Receptor-to-MAPK Signaling Axis
Authors: Filardo Edward J. , Quinn Jeffrey A. , Frackelton A. Raymond , Bland Kirby I.
Published: January 2014

Estrogen triggers rapid yet transient activation of the MAPKs, extracellular signal-regulated kinase (Erk)-1 and Erk-2. We have reported that this estrogen action requires the G protein-coupled receptor, GPR30, and occurs via Gβγ-subunit protein-dependent transactivation of the epidermal growth factor (EGF) receptor through the release of pro-heparan-bound EGF from the cell surface. Here we investigate the mechanism by which Erk-1/-2 activity is rapidly restored to basal levels after estrogen stimulation. Evidence is provided that attenuation of Erk-1/-2 activity by estrogen occurs via GPR30-dependent stimulation of adenylyl cyclase and cAMP-dependent signaling that results in Raf-1 inactivation. We show that 17β-E2 represses EGF-induced activation of the Raf-to-Erk pathway in human breast carcinoma cells that express GPR30, including MCF-7 and SKBR3 cells which express both or neither, ER, respectively. MDA-MB-231 cells, which express ERβ, but not ERα, and low levels of GPR30 protein, are unable to stimulate adenylyl cyclase or promote estrogen-mediated blockade of EGF-induced activation of Erk-1/-2. Pretreatment of MDA-MB-231 cells with cholera toxin, which ADP-ribosylates and activates Gαs subunit proteins, results in G protein-coupled receptor (GPCR)-independent adenylyl cyclase activity and suppression of EGF-induced Erk-1/-2 activity. Transfection of GPR30 into MDA-MB-231 cells restores their ability to stimulate adenylyl cyclase and attenuate EGF-induced activation of Erk-1/-2 by estrogen. Moreover, GPR30-dependent, cAMP-mediated attenuation of EGF-induced Erk-1/-2 activity was achieved by ER antagonists such as tamoxifen or ICI 182, 780; yet not by 17α-E2 or progesterone. Thus, our data delineate a novel mechanism, requiring GPR30 and estrogen, that acts to regulate Erk-1/-2 activity via an inhibitory signal mediated by cAMP. Coupled with our prior findings, these current data imply that estrogen balances Erk-1/-2 activity through a single GPCR via two distinct G protein-dependent signaling pathways that have opposing effects on the EGF receptor-to-MAPK pathway.
PRL Modulates Cell Cycle Regulators in Mammary Tumor Epithelial Cells
Authors: Schroeder Matthew D. , Symowicz Jaime , Schuler Linda A.
Published: January 2014

PRL is essential for normal lobulo-alveolar growth of the mammary gland and may contribute to mammary cancer development or progression. However, analysis of the mechanism of action of PRL in these processes is complicated by the production of PRL within mammary epithelia. To examine PRL actions in a mammary cell-specific context, we selected MCF-7 cells that lacked endogenous PRL synthesis, using PRL stimulation of interferon-γ-activated sequence-related PRL response elements. Derived clones exhibited a greater proliferative response to PRL than control cells. To understand the mechanism, we examined, by Western analysis, levels of proteins essential for cell cycle progression as well as phosphorylation of retinoblastoma protein. The expression of cyclin D1, a critical regulator of the G1/S transition, was significantly increased by PRL and was associated with hyperphosphorylation of retinoblastoma protein at Ser780. Cyclin B1 was also increased by PRL. In contrast, PRL decreased the Cip/Kip family inhibitor, p21, but not p16 or p27. These studies demonstrate that PRL can stimulate the cell cycle in mammary epithelia and identify specific targets in this process. This model system will enable further molecular dissection of the pathways involved in PRL-induced proliferation, increasing our understanding of this hormone and its interactions with other factors in normal and pathogenic processes.
14-3-3 Facilitates Insulin-Stimulated Intracellular Trafficking of Insulin Receptor Substrate 1
Authors: Xiang Xiaoqin , Yuan Mingsheng , Song Ying , Ruderman Neil , Wen Rong , Luo Zhijun
Published: January 2014

The appearance of a complex between tyrosine-phosphorylated insulin receptor substrate 1 (IRS-1) and PI3K in a high-speed pellet fraction (HSP) is thought to be a key event in insulin action. Conversely, the disappearance of the IRS-1/PI3K complex from this fraction has been linked to insulin desensitization. The present study examines the role of 14-3-3, a specific phospho-serine binding protein, in mediating the disappearance of IRS-1 from the HSP after insulin treatment. An in vitro pull-down assay using recombinant 14-3-3 revealed that insulin enhances the association of 14-3-3 with IRS-1 in cultured adipocytes and that this is completely inhibited by wortmannin. An association of IRS-1 and 14-3-3 was also observed and was maximal after stimulation by insulin, when endogenous proteins were immunoprecipitated. Epidermal growth factor (EGF), 12-O-tetradecanoylphorbol-13-acetate, and okadaic acid, other agents that cause serine/threonine phosphorylation of IRS-1, also stimulated IRS binding to 14-3-3. The enhancement of IRS-1 binding to 14-3-3 by insulin was accompanied by movement of IRS-1 and the p85 subunit of PI3K from the HSP to the cytosol. In keeping with a key role of 14-3-3 in mediating this redistribution of IRS-1, the complexes of IRS-1 and 14-3-3 were found in the cytosol but not in the HSP of insulin-treated cells. In addition, colocalization of IRS-1 and 14-3-3 was observed in the cytoplasm after insulin treatment by confocal microscopy. Finally, the addition of a phosphorylated 14-3-3 binding peptide to an adipocyte homogenate (to remove 14-3-3 from IRS-1) increased the abundance of IRS-1/PI3K complexes in the HSP and decreased their abundance in the cytosol. These findings strongly suggest that 14-3-3 participates in the intracellular trafficking of IRS-1 by promoting the displacement of serine-phosphorylated IRS-1 from particular structures. They also suggest that 14-3-3 proteins could play an integral role in the process of insulin desensitization.
Ovulatory Surges of Human CG Prevent Hormone-Induced Granulosa Cell Tumor Formation Leading to the Identification of Tumor-Associated Changes in the Transcriptome
Authors: Owens Gabe E. , Keri Ruth A. , Nilson John H.
Published: January 2014

Granulosa cell tumors comprise approximately 10% of ovarian tumors and, although rare, are clinically important due to their potential for malignancy and recurrence. Although their morphological features have been carefully described, the global changes in gene expression associated with their formation remain undetermined. To initiate this characterization, we used a transgenic mouse model in which granulosa cell tumors occur with 100% penetrance in CF-1 mice that harbor a novel transgene encoding a chimeric LHβ subunit. When this transgene is expressed in other strains of mice, including (C57BL/6♀ × CF-1♂,Tg) F1 hybrids, luteomas develop even though levels of LH remain high. This dichotomous response permits a longitudinal comparison of global changes in transcriptomes uniquely associated with either granulosa cell tumors or luteomas. Herein we report numerous changes in the transcriptome, including a decrease in LH receptor mRNA and increases in several mRNAs that encode secreted proteins previously associated with granulosa cell tumors. Furthermore, we identified a constellation of mRNAs that encode proteins that may serve as new markers for this tumor phenotype. Additional experiments indicated that periodic treatment with human CG prevented formation of granulosa cell tumors in mice genetically predisposed to tumor development and, instead, led to the appearance of luteomas. More importantly, ovarian transcriptomes from the luteomas induced by ovulatory doses of human CG permitted refined confirmation of gene expression changes that were uniquely associated with either granulosa cell tumors in the permissive CF-1 genetic background or in luteomas in the F1 hybrids. Together, these dynamic changes in the ovarian transcriptome indict various signaling pathways potentially involved in mediating the actions of LH over time and, depending on genetic background, the formation of either a luteoma or a granulosa cell tumor.
Functional Microarray Analysis of Mammary Organogenesis Reveals a Developmental Role in Adaptive Thermogenesis
Authors: Master Stephen R. , Hartman Jennifer L. , D’Cruz Celina M. , Moody Susan E. , Keiper Elizabeth A. , Ha Seung I. , Cox James D. , Belka George K. , Chodosh Lewis A.
Published: January 2014

The use of DNA microarrays to study vertebrate organogenesis presents unique analytical challenges compared with expression profiling of homogeneous cell populations. We have used a general approach that permits the automated, unbiased identification of biologically relevant patterns of gene expression to study murine mammary gland development. Our studies confirm the utility of this approach by demonstrating the ready identification of cellular processes and pathways of known functional importance in mammary development. Additionally, this approach permitted the identification of genetic pathways with unpredicted patterns of developmental regulation, including those involved in angiogenesis, extracellular matrix synthesis, and the β-oxidation of fatty acids. Surprisingly, our findings demonstrate that the coordinate regulation of genes involved in the β-oxidation of fatty acids reflects the presence of an abundant, yet previously unrecognized stromal compartment within the mammary gland that is composed of brown adipose tissue. Our data demonstrate that the amount of brown adipose tissue present in the mammary gland is developmentally regulated; that PPARα, Ucp1, and genes involved in fatty acid oxidation are spatially and temporally coregulated during development; that the mammary gland plays a functional role in adaptive thermogenesis; and that the transcriptional control of this adaptive response to cold is itself developmentally regulated.
Synergistic Action of Prolactin (PRL) and Androgen on PRL-Inducible Protein Gene Expression in Human Breast Cancer Cells: A Unique Model for Functional Cooperation between Signal Transducer and Activator of Transcription-5 and Androgen Receptor
Authors: Carsol Jean-Louis , Gingras Sébastien , Simard Jacques
Published: January 2014

The signal transducer and activator of transcription 5 (Stat5) has been shown to cooperate with some nuclear receptors. However, an interaction has never been demonstrated with the androgen receptor (AR). Given that the PRL-inducible protein/gross cystic disease fluid-15 (PIP/GCDFP-15) is both a PRL-controlled and an androgen-controlled protein, we used its promoter region to investigate the potential interaction between Stat5 and androgen receptor. Dihydrotestosterone or PRL alone slightly modulated or did not modulate the luciferase activity of all reporter gene constructs. In contrast, a maximal increase was observed using the −1477+42 reporter gene construct after exposure to both dihydrotestosterone and PRL. The requirement of half-site androgen-responsive elements and two consensus Stat5-binding elements, Stat5#1 and Stat5#2, was determined by site-directed mutagenesis. Activated Stat5B binds with a higher affinity to Stat5#2 than to Stat5#1. Stat5AΔ749 and Stat5BΔ754 mutants demonstrated that the Stat5 trans-activation domain is involved in the hormonal cooperation. The cooperation depends on the PRL-induced phosphorylation on Tyr694 in Stat5A and Tyr699 in Stat5B, as demonstrated using the Stat5AY694F and Stat5BY699F proteins. The use of AR Q798E, C619Y, and C784Y mutants showed that trans-activation, DNA-binding, and ligand-binding domains of AR are essential. Our study thus suggests a functional cooperation between AR and Stat5.
Estrogen Receptor α and Aromatase Polymorphisms Affect Risk, Prognosis, and Therapeutic Outcome in Men with Castration-Resistant Prostate Cancer Treated with Docetaxel-Based Therapy
Authors: Sissung Tristan M. , Danesi Romano , Kirkland C. Tyler , Baum Caitlin E. , Ockers Sandra B. , Stein Erica V. , Venzon David , Price Douglas K. , Figg William D.
Published: January 2014

Context

Reactive estrogen species cause genotoxicity and interfere with docetaxel-mediated tubulin polymerization resulting in shortened survival in men with castrate-resistant prostate cancer (CRPC).

Objective

We hypothesized that polymorphisms in estrogen synthesis and estrogen targets (i.e., CYP19 and ERα) would be linked to interindividual variation in CRPC risk, docetaxel response, and overall survival (OS) in men with CRPC.

Materials and Methods

Patients with CRPC (n = 115) treated with docetaxel, single-agent thalidomide (n = 42), or healthy controls (n = 289) were genotyped for the CYP19 R264C (rs700519) and the ERα PvuII T> C (rs2234693) and XbaI A> G (rs9340799) polymorphisms.

Results

Patients carrying two copies of ERα polymorphisms had shorter progression-free survival on docetaxel than other patients (median survival difference ≥3.1 months; P ≤ 0.036). When the analysis was limited to nonobese patients, the relationship between the ERα XbaI A> G polymorphism and PFS improved (median survival difference = 3.5 months; P = 0.0078). The CYP19 R264C variant was related to the duration of survival after docetaxel in patients who were > 70 years old (median survival difference = 10.6 months; P = 0.041). Both ERα polymorphisms were also associated with increases in CRPC risk [P ≤ 0.032; double variants vs. wild-type odds ratio (OR) ≥ 2.6], and the association with the ERα PvuII T> C also improved in those men who were < 70 years old (P = 0.0073; OR = 3.0).

Conclusions

This study demonstrates that estrogen-related genetic variation affects docetaxel clinical response and that this relationship is dependent on age and body-type in men with CRPC. Moreover, this study suggests ERα polymorphisms confer risk of developing prostate cancer, especially in men under 70 years of age.
Photocatalytic Activity of Rutile Titania for Hydrogen Evolution
Authors: Amano Fumiaki , Nakata Masashi , Ishinaga Eri
Published: January 2014

Herein, we demonstrate the high photocatalytic activity of rutile particles for H2 evolution from aqueous ethanol solution. The rutile particles were prepared by successive calcination at 900 °C and H2 reduction treatment at 700 °C of commercial anatase-rich TiO2 powder, Evonik/Degussa P25.
Silica-supported Tripod Triarylphosphines: Application to Palladium-catalyzed Borylation of Chloroarenes
Authors: Iwai Tomohiro , Harada Tomoya , Tanaka Ryotaro , Sawamura Masaya
Published: January 2014

Silica-supported tripod triarylphosphines that have a Ph3P-type core tripodally immobilized on a silica surface enabled the Pd-catalyzed borylation of chloroarenes with bis(pinacolato)diboron under mild conditions. The immobilization in tripod was crucial for the excellent performance of the Ph3P-based ligands.
O ciclo de vida e o posicionamento competitivo dos produtos turísticos de Foz do Iguaçu desde a perspectiva dos atores locais
Authors: Gonçalves Gândara José Manoel , Domareski Ruiz Thays Cristina , Chim-Miki Adriana Fumi , Biz Alexandre
Published: January 2014

Este artigo apresenta e analisa um diagnóstico reflexivo da percepção dos principais atores locais, envolvidos no planejamentoe na gestão da atividade turística no destino de Foz do Iguaçu-Br. Odiagnóstico foi elaborado a partir de uma metodologiaestratégico/participativa, que teve por objetivo produzir um material queefetivamente refletisse a realidade turística da região e as opiniões dacomunidade local, buscando socializar informações para facilitar a tomada de decisões,tanto da iniciativa pública como da iniciativa privada e garantir ocomprometimento de todos os envolvidos na produção deste documento nautilização do mesmo como um instrumento para dar continuidade ao processo deconstrução do destino desejado. Por outro lado, a análise deste diagnósticobuscou verificar o posicionamento competitivo do destino turístico contextualizadosaos estágios de ciclo de vida dos produtos turísticos, e frente a seusprincipais competidores, utilizando os fatores externos e internos como fundamentopara as dinâmicas e inércias do segmento turístico da cidade, e, portanto comodeterminantes da competitividade.
Hypothalamic Dysfunction of the Thrombospondin Receptor α2δ-1 Underlies the Overeating and Obesity Triggered by Brain-Derived Neurotrophic Factor Deficiency
Authors: Cordeira Joshua W. , Felsted Jennifer A. , Teillon Sarah , Daftary Shabrine , Panessiti Micaella , Wirth Jena , Sena-Esteves Miguel , Rios Maribel
Published: January 2014

Brain-derived neurotrophic factor (BDNF) and its receptor, TrkB, are critical components of the neural circuitry controlling appetite and body weight. Diminished BDNF signaling in mice results in severe hyperphagia and obesity. In humans, BDNF haploinsufficiency and the functionalBdnfVal66Met polymorphism have been linked to elevated food intake and body weight. The mechanisms underlying this dysfunction are poorly defined. We demonstrate a chief role of α2δ-1, a calcium channel subunit and thrombospondin receptor, in triggering overeating in mice with central BDNF depletion. We show reduced α2δ-1 cell-surface expression in the BDNF mutant ventromedial hypothalamus (VMH), an energy balance-regulating center. This deficit contributes to the hyperphagia exhibited by BDNF mutant mice because selective inhibition of α2δ-1 by gabapentin infusion into wild-type VMH significantly increases feeding and body weight gain. Importantly, viral-mediated α2δ-1 rescue in BDNF mutant VMH significantly mitigates their hyperphagia, obesity, and liver steatosis and normalizes deficits in glucose homeostasis. Whole-cell recordings in BDNF mutant VMH neurons revealed normal calcium currents but reduced frequency of EPSCs. These results suggest calcium channel-independent effects of α2δ-1 on feeding and implicate α2δ-1–thrombospondin interactions known to facilitate excitatory synapse assembly. Our findings identify a central mechanism mediating the inhibitory effects of BDNF on feeding. They also demonstrate a novel and critical role for α2δ-1 in appetite control and suggest a mechanism underlying weight gain in humans treated with gabapentinoid drugs.
Coexistencia de variantes HIV-1 com insercao dipeptidica no gene da transcriptase reversa
Authors: Tanikawa Aline Aki , Barreto Sarita Fiorelli Dias , Grotto Rejane Maria Tommasini , Pardini Maria Ines de Moura Campos
Published: January 2014

O objetivo desta comunicação foi descrever a detecção de coexistência de variantes HIV-1 com inserções de dois aminoácidos entre os códons 69 e 70 da transcriptase reversa. Tais variantes foram isoladas de paciente do sexo masculino, 16 anos de idade, em tratamento no interior do estado de São Paulo. Após confirmação de falha terapêutica, foi realizado teste de resistência a antirretrovirais, a partir do qual foram detectadas duas variantes contendo inserções dos aminoácidos Ser-Gly/Ser-Ala no códon 69 da transcriptase reversa, além da mutação T69S. Tais inserções possuem baixa prevalência, não foram relatadas em caráter de coexistência no Brasil e estão relacionadas com a resistência a múltiplas drogas, tornando o achado relevante do ponto de vista epidemiológico.
Aggression and self-aggression syndrome in females suffering from bulimia nervosa
Authors: Izydorczyk Bernadetta
Published: January 2014

The current study is aimed at creating a psychological profile of characteristics of aggressive and self-aggressive behaviour exhibited by females with bulimia, as well as conducting a comparative analysis of the differences between bulimic females and individuals displaying no mental disorders in terms of the major characteristics of aggressive and selfaggressive behaviour. The methods: the Buss-Durkee Hostility-Guilt Inventory, the Psychological Inventory of Aggression Syndrome by Zbigniew. B. Gaś. The data analysis revealed significant differences between the females suffering from bulimia and the subjects displaying no mental disorders in terms of the level of aggressive and self-aggressive tendencies. It was discovered that the control participants exhibited an appropriate level of aggressive behaviour as opposed to the subjects with bulimia.
Association between social support and temperament and the intensity of PTSD symptoms in a sample of HIV positives
Authors: Rzeszutek Marcin , Oniszczenko Włodzimierz
Published: January 2014

The aim of this study was to investigate the association between temperament and social support and the level of quantitatively rated PTSD symptoms in a sample of HIV+ and HIV/AIDS men and women. A total of 310 men and women, including 182 HIV+ and 128 HIV/AIDS, were studied. Social support was assessed with the Berlin Social Support Scales (BSSS). Temperament was assessed with the Formal Characteristics of Behaviour - Temperament Inventory (FCBTI). Intensity of PTSD symptoms was assessed with the PTSDF (PTSD Factorial Version inventory). The best predictors of intensity of PTSD symptoms in HIV+ participants were support seeking and sensory sensitivity. Support seeking was positively associated, and sensory sensitivity was negatively associated with intensity of PTSD symptoms.
Male homophobia, touch, and compliance: A matter of the touched, not the toucher
Authors: Dolinski Dariusz
Published: January 2014

Numerous studies have shown that people are more likely to fulfill requests made by a stranger when he or she touches their arm or forearm slightly while asking. In Poland, however, where male homophobia is widespread, interpersonal touch decreases compliance when man touches another man. It has also been demonstrated in previous studies that highly homophobic male participants are especially unwilling to fulfill requests while touched. In this paper the hypothesis that also confederates’ homophobia create an additional factor inhibiting compliance with request formulated by men touching other men was tested in two experiments. No relations, however, was found between confederates’ level of homophobia and participants’ reaction.