bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bone Density and Amenorrhea in Ballet Dancers Are Related to a Decreased Resting Metabolic Rate and Lower Leptin Levels
Authors: Kaufman Becky A. , Warren Michelle P. , Dominguez Jennifer E. , Wang Jack , Heymsfield Steven B. , Pierson Richard N. 
Published: January 2014

Osteopenia, which is correlated with amenorrhea and poor nutritional habits, has been well documented in elite ballet dancers. Estrogen replacement therapy and recovery from amenorrhea have not been associated with normalization of bone density. Thus, the osteopenia may be related to changes brought about by chronic dieting or other factors, such as a hypometabolic state induced by poor nutrition. The purpose of this study was to investigate the relationship of chronic dieting and resting metabolic rate (RMR) to amenorrhea and bone density.RMR, bone density, eating disorder assessments, leptin levels, and complete menstrual and medical histories were determined in 21 elite ballet dancers and in 27 nondancers (age, 20–30 yr). No significant correlations were found between high EAT26 scores, a measure of disordered eating, and RMR, bone densities, body weight, body fat, or fat-free mass. However, when RMR was adjusted for fat-free mass (FFM), a significant positive correlation was found between RMR/FFM and bone density in both the arms (P &lt; 0.001) and spine (P &lt; 0.05) in ballet dancers, but not in the normal controls. The dancers also demonstrated significantly higher EAT scores (22.9 ± 10.3 vs. 4.1 ± 2.4; P &lt; 0.001) and lower RMR/FFM ratios (30.0 ± 2.2 vs. 32.05 ± 2.8; P &lt; 0.01). The only variable to predict lower RMR/FFM in the entire sample was ever having had amenorrhea; this group had significantly higher EAT scores (18.0 ± 13.5 vs. 10.3 ± 10.2; P &lt; 0.05), lower leptin levels (4.03 ± 0.625 vs. 7.10 ± 4.052; P &lt; 0.05), and lower bone mineral density in the spine (0.984 ± 0.11 vs. 1.10 ± 0.13; P &lt; 0.05) and arm (0.773 ± 0.99 vs. 0.818 ± 0.01; P &lt; 0.05).We hypothesize that the correlation between low RMR and lower leptin levels and bone density may be more strongly related to nutritional habits in ballet dancers, causing significant depression of RMR, particularly for those with a history of amenorrhea.
Identification of Trophoblast-Specific Regulatory Elements in the Mouse Placental Lactogen II Gene
Authors: Lin Jiandie , Linzer Daniel I. H. 
Published: January 2014

AbstractPlacental lactogen II, the major ligand for the PRL receptor during the second half of gestation in rodents, is synthesized specifically by placental trophoblast giant cells. A transient transgenic analysis has been used to localize the giant cell-specific regulatory region within the mouse placental lactogen II gene to sequences between −1340 and −2019 upstream of the transcriptional start site. More precise mapping of the regulatory elements has been accomplished by transfection of promoter constructs into Rcho-1 trophoblast cells, resulting in the characterization of two positive regulatory elements in the −1471 to −1340 region; two other regulatory elements have been implicated but not further characterized, a negative regulatory element between −2019 and −1778 and another positive element within the region from −1340 to −569. Both of the characterized positive regulatory elements are recognized by factors that are enriched in differentiated giant cells compared with proliferative trophoblasts, and these factors are either absent or at low levels in fibroblasts. The complexes that form on the two elements are distinct and neither element competes with the other for factor binding, thus implicating at least two different regulatory elements in late-gestational trophoblast giant cell-specific gene expression.
Differential Regulation of Basal and Cyclic Adenosine 3′,5′-Monophosphate-Induced Somatostatin Gene Transcription in Neural Cells by DNA Control Elements That Bind Homeodomain Proteins
Authors: Schwartz Petra T. , Vallejo Mario 
Published: January 2014

AbstractA number of genes encoding neuropeptides are expressed in the peripheral and central nervous systems, in different endocrine organs, and in specialized cells distributed along the gastrointestinal tract. Whether expression of the same neuropeptide gene in different tissues is regulated by similar transcriptional mechanisms or by mechanisms that differ in a cell-specific manner remains unclear. We report on promoter studies on the regulation of the somatostatin gene in immortalized neural precursor cells derived from developing rat forebrain. Expression of the somatostatin gene in these cells was determined by RT-PCR/Southern blot analysis, by immunocytochemistry, and by RIA. We show that in cerebrocortical and hippocampal cells, expression of the somatostatin gene is regulated by several negative and positive DNA cis-regulatory elements located throughout the promoter region. The somatostatin cAMP-response element appears to play a prominent role in neural somatostatin gene expression by acting as a strong enhancer even in the absence of cAMP stimulation. Site-directed mutagenesis followed by transient transfection assays indicated that SMS-TAAT1, SMS-TAAT2, and SMS-UE, three previously identified homeodomain protein-binding regulatory elements that enhance transcription in pancreatic cells, act as repressors of transcription in neural cells. Electrophoretic mobility shifts assays indicate that those elements bind protein complexes that differ between neural and pancreatic cells. Our results support the notion that expression of the somatostatin gene in neural cells occurs via transcriptional mechanisms that are different from those regulating expression of the same gene in pancreatic cells.
Conditional Disruption of the Aryl Hydrocarbon Receptor Nuclear Translocator (Arnt) Gene Leads to Loss of Target Gene Induction by the Aryl Hydrocarbon Receptor and Hypoxia-Inducible Factor 1α
Authors: Tomita Shuhei , Sinal Christopher J. , Yim Sun Hee , Gonzalez Frank J. 
Published: January 2014

AbstractTo determine the function of the aryl hydrocarbon receptor nuclear translocator (ARNT), a conditional gene knockout mouse was made using the Cre-loxP system. Exon 6, encoding the conserved basic-helix-loop-helix domain of the protein, was flanked by loxP sites and introduced into the Arnt gene by standard gene disruption techniques using embryonic stem cells. Mice homozygous for the floxed allele were viable and had no readily observable phenotype. The Mx1-Cre transgene, in which Cre is under control of the interferon-γ promoter, was introduced into the Arnt-floxed mouse line. Treatment with polyinosinic-polycytidylic acid to induce expression of Cre resulted in complete disruption of the Arnt gene and loss of ARNT messenger RNA (mRNA) expression in liver. To determine the role of ARNT in gene control in the intact animal mouse liver, expression of target genes under control of an ARNT dimerization partner, the aryl hydrocarbon receptor (AHR), was monitored. Induction of CYP1A1, CYP1A2, and UGT1*06 mRNAs by the AHR ligand 2,3,7,8-tetrachlorodibenzo-pdioxin was absent in livers of Arnt-floxed/Mx1-Cre mice treated with polyinosinic-polycytidylic. These data demonstrate that ARNT is required for AHR function in the intact animal. Partial deletion of the Arnt allele was found in kidney, heart, intestine, and lung. Despite more than 80% loss of the ARNT expression in lung, maximal induction of CYP1A1 was found, indicating that the expression level of ARNT is not limiting to AHR signaling. Cobalt chloride induction of the glucose transporter-1 and heme oxygenase-1 mRNAs was also markedly abrogated in mice lacking ARNT expression, suggesting an inhibition of HIF-1α activity. These studies establish a critical role for ARNT in AHR and HIF-1α signal transduction in the intact mouse.
25-Dehydro-1α-Hydroxyvitamin D3- 26,23S-Lactone Antagonizes the Nuclear Vitamin D Receptor by Mediating a Unique Noncovalent Conformational Change
Authors: Bula C. M. , Bishop J. E. , Ishizuka S. , Norman A. W. 
Published: January 2014

Abstract(23S)-25-dehydro-1α-Dihydroxyvitamin D3-26,23-lactone (TEI-9647; MK) has been reported to antagonize the 1α,25-dihydroxyvitamin D3 nuclear receptor (VDR)- mediated increase in transcriptional activity. Using a transient transfection system incorporating the osteocalcin VDRE (vitamin D response element) in Cos-1 cells, we found that 20 nm MK antagonizes VDR-mediated transcription by 50% when driven by 1 nm 1α,25(OH)2D3. Four analogs of 1α,25(OH)2D3, also at 1 nm, were antagonized 25 to 39% by 20 nm MK. However, analogs with 16-ene/23-yne or 20-epi modifications, which have a significantly lower agonist ED50 for the VDR than 1α,25(OH)2D3, were antagonized by 20 nm MK only at 100 pm or 10 pm, respectively. One possible mechanism for antagonism is that the 25-dehydro alkene of MK might covalently bind the ligand-binding site of the VDR rendering it inactive. Utilization of a ligand exchange assay, however, demonstrated that MK bound to VDR is freely exchanged with 1α,25(OH)2D3 in vitro. These data support the apparent correlation between VDR transcriptional activation by agonists and the effective range of MK antagonism by competition. Furthermore, protease sensitivity analysis of MK bound to VDR indicates the presence of a unique conformational change in the VDR ligand-binding domain, showing a novel doublet of VDR fragments centered at 34 kDa, whereas 1α,25(OH)2D3 as a ligand produces only a single 34-kDa fragment. In comparison, the natural metabolite 1α,25dihydroxyvitamin D3-26,23-lactone yields only the 30-kDa fragment that is produced by all ligands to varying degrees. Collectively, these results support that MK is a potent partial antagonist of the VDR for 1α,25(OH)2D3 and its analogs when in appropriate excess of the agonist.
Temporally Distinct and Ligand-Specific Recruitment of Nuclear Receptor-Interacting Peptides and Cofactors to Subnuclear Domains Containing the Estrogen Receptor
Authors: Schaufele Fred , Chang Ching-yi , Liu Weiqun , Baxter John D. , Nordeen Steven K. , Wan Yihong , Day Richard N. , McDonnell Donald P. 
Published: January 2014

AbstractLigand binding to estrogen receptor (ER) is presumed to regulate the type and timing of ER interactions with different cofactors. Using fluorescence microscopy in living cells, we characterized the recruitment of five different green fluorescent protein (GFP)-labeled ER-interacting peptides to the distinct subnuclear compartment occupied by blue fluorescent protein (BFP)-labeled ERα. Different ligands promoted the recruitment of different peptides. One peptide was recruited in response to estradiol (E2), tamoxifen, raloxifene, or ICI 182,780 incubation whereas other peptides were recruited specifically by E2 or tamoxifen. Peptides containing different sequences surrounding the ER-interacting motif LXXLL were recruited with different time courses after E2 addition. Complex temporal kinetics also were observed for recruitment of the full-length, ER cofactor glucocorticoid receptor-interacting protein 1 (GRIP1); rapid, E2-dependent recruitment of GRIP1 was blocked by mutation of the GRIP1 LXXLL motifs to LXXAA whereas slower E2 recruitment persisted for the GRIP1 LXXAA mutant. This suggested the presence of multiple, temporally distinct GRIP 1 recruitment mechanisms. E2 recruitment of GRIP1 and LXXLL peptides was blocked by coincubation with excess ICI 182,780. In contrast, preformed E2/ER/GRIP1 and E2/ER/LXXLL complexes were resistant to subsequent ICI 182,780 addition whereas ICI 182,780 dispersed preformed complexes containing the GRIP1 LXXAA mutant. This suggested that E2-induced LXXLL binding altered subsequent ligand/ER interactions. Thus, alternative, ligand-selective recruitment and dissociation mechanisms with distinct temporal sequences are available for ERα action in vivo.
PRL-Induced ERα Gene Expression Is Mediated by Janus Kinase 2 (Jak2) While Signal Transducer and Activator of Transcription 5b (Stat5b) Phosphorylation Involves Jak2 and a Second Tyrosine Kinase
Authors: Frasor Jonna , Barkai Uriel , Zhong Liping , Fazleabas Asgerally T. , Gibori Geula 
Published: January 2014

AbstractIn the rat corpus luteum of pregnancy, PRL stimulation of ER expression is a prerequisite for E2 to have any luteotropic effect. Previous work from our laboratory has established that PRL stimulates ERα expression at the level of transcription and that the transcription factor Stat5 (signal transducer and activator of transcription 5) mediates this stimulation. Since it is well established that PRL activates Stat5 through the tyrosine kinase, Janus kinase 2 (Jak2), the role of Jak2 in PRL regulation of ERα expression was investigated. In primary luteinized granulosa cells, the general tyrosine kinase inhibitors, genistein and AG18, and the Jak2 inhibitor, AG490, prevented PRL stimulation of ERα mRNA levels, suggesting that PRL signaling to the ERα gene requires Jak2 activity. However, using an antibody that recognizes the tyrosine-phosphorylated forms of both Stat5a and Stat5b (Y694/Y699), it was found that AG490 could inhibit PRL-induced Stat5a phosphorylation only and had little or no effect on Stat5b phosphorylation. These effects of AG490 were confirmed in COS cells overexpressing Stat5b. Also in COS cells, a kinase-negative Jak2 prevented PRL stimulation of ERα promoter activity and Stat5b phosphorylation while a constitutively active Jak2 could stimulate both in the absence of PRL. Furthermore, kinase-negative-Jak2, but not AG490, could inhibit Stat5b nuclear translocation and DNA binding. Therefore, it seems that in the presence of AG490, Stat5b remains phosphorylated, is located in the nucleus and capable of binding DNA, but is apparently transcriptionally inactive. These findings suggest that PRL may activate a second tyrosine kinase, other than Jak2, that is capable of phosphorylating Stat5b without inducing transcriptional activity. To investigate whether another signaling pathway is involved, the src kinase inhibitor PP2 and the phosphoinositol-3 kinase inhibitor (PI3K), LY294002, were used. Neither inhibitor alone had any major effect on PRL regulation of ERα promoter activity or on PRL-induced Stat5b phosphorylation. However, the combination of AG490 and LY294002 largely prevented PRL-induced Stat5b phosphorylation. These findings indicate that PRL stimulation of ERα expression requires Jak2 and also that PRL can induce Stat5b phosphorylation through two tyrosine kinases, Jak2 and one downstream of PI3K. Furthermore, these results suggest that the role of Jak2 in activating Stat5b may be through a mechanism other than simply inducing Stat5b phosphorylation.
Direct Regulation of β3-Integrin Subunit Gene Expression by HOXA10 in Endometrial Cells
Authors: Daftary Gaurang S. , Troy Patrick J. , Bagot Catherine N. , Young Steven L. , Taylor Hugh S. 
Published: January 2014

AbstractEstrogen and progesterone regulate HOXA10 expression in the endometrium, where HOXA10 is necessary for implantation. The integrins are also involved in early embryo-endometrial interactions. Here we show that HOXA10 directly regulates β3-integrin subunit expression in the endometrium, likely mediating the effect of sex steroids on β3-integrin expression. β3-Integrin expression was decreased in endometrium shown to have low HOXA10 expression. β3-Integrin mRNA levels were increased in endometrial adenocarcinoma cells (Ishikawa) transfected with pcDNA3.1/HOXA10, and decreased in cells treated with HOXA10 antisense. Seven consensus HOXA10 binding sites were identified 5′ of the β3-integrin gene. Direct binding of HOXA10 protein to four sites was demonstrated by EMSA. Reporter gene expression increased in BT-20 cells cotransfected with pcDNA3.1/ HOXA10 and pGL3-promoter vector containing region F (encompassing all seven HOXA10 consensus sites). A 41-bp segment (Region A) showed highest affinity binding to HOXA10 protein. Increased reporter expression, equal in magnitude to that obtained with Region F, was obtained with Region A. HOXA10 protein binding within Region A was localized by deoxyribonuclease I footprinting. β3-Integrin expression was directly up-regulated by HOXA10 through a 41-bp 5′-regulatory element. Sex steroids regulate the expression of endometrial β3-integrin through a pathway involving HOXA10.
Pregnane X Receptor (PXR), Constitutive Androstane Receptor (CAR), and Benzoate X Receptor (BXR) Define Three Pharmacologically Distinct Classes of Nuclear Receptors
Authors: Moore Linda B. , Maglich Jodi M. , McKee David D. , Wisely Bruce , Willson Timothy M. , Kliewer Steven A. , Lambert Millard H. , Moore John T. 
Published: January 2014

Abstract
The NR1I subfamily of nuclear receptors contains a phylogenetically diverse array of receptors related to the mammalian pregnane X receptor (PXR) (NR1I2) and constitutive androstane receptor (CAR) (NR1I3). We have carried out an extensive comparative analysis of this subgroup with representatives from fish, birds, amphibians, and mammals. Four novel receptors were isolated from fish, dog, pig, and monkey for this study and combined with a previously reported set of related receptors including human PXR, rabbit PXR, mouse PXR, chicken CXR, frog benzoate X receptors (BXRα, BXRβ), and human and mouse CAR. A broad range of xenobiotics, steroids, and bile acids were tested for their ability to activate the ligand binding domain of each receptor. Three distinct groups of receptors were identified based on their pharmacological profiles: 1) the PXRs were activated by a broad range of xenobiotics and, along with the mammalian PXRs, included the chicken and fish receptors; 2) the CARs were less promiscuous, had high basal activities, and were generally repressed rather than activated by those compounds that modulated their activity; and 3) the BXRs were selectively activated by a subset of benzoate analogs and are likely to be specialized receptors for this chemical class of ligands. The PXRs are differentiated from the other NR1I receptors by a stretch of amino acids between helices 1 and 3, which we designate the H1–3 insert. This insert was present in the mammalian, chicken, and fish PXRs but absent in the CARs and BXRs. Modeling studies suggest that the H1–3 insert contributes to the promiscuity of the PXRs by facilitating the unwinding of helices-6 and -7, thereby expanding the ligand binding pocket.
Direct Interactions between Corepressors and Coactivators Permit the Integration of Nuclear Receptor-Mediated Repression and Activation
Authors: Li Xiaolin , Kimbrel Erin A. , Kenan Daniel J. , McDonnell Donald P. 
Published: January 2014

Abstract
The unliganded thyroid hormone receptor β (TRβ) represses the basal transcriptional activity of target genes, in part through interactions with the nuclear receptor corepressor (N-CoR). In this study we have identified a rather unexpected interaction between N-CoR and the nuclear receptor coactivator ACTR. We have demonstrated in vitro and in intact cells that N-CoR directly associates with ACTR and that the interaction surfaces on N-CoR and ACTR are distinct from those required for TR binding. The significance of this finding was demonstrated by showing that N-CoR facilitates an interaction between unliganded-TRβ and ACTR. One possible consequence of the formation of the trimeric complex of N-CoR/ACTR/unliganded-TR is that N-CoR may raise the local concentration of ACTR at target gene promoters. In support of this hypothesis it was demonstrated that the presence of N-CoR can enhance TRβ-mediated transcriptional activation. It is proposed, therefore, that TRβ- mediated activation and repression are integrally linked in a manner that is not predicted by the current models of nuclear receptor action.
Characterization of a New Upstream GnRH Receptor Promoter in Human Ovarian Granulosa-Luteal Cells
Authors: Cheng Chi Keung , Yeung Chung Man , Chow Billy K. C. , Leung Peter C. K. 
Published: January 2014

Abstract
GnRH has been implicated as an important local autocrine and paracrine factor in regulating ovarian function. However, to date, the transcriptional regulation of GnRH receptor (GnRHR) gene in human ovary remains poorly understood. Here we report the characterization of a new upstream promoter for the GnRHR gene in human granulosa-luteal cells. Using progressive deletion analysis, a region between nucleotide −1300 and −1018 (relative to the translation start site) was shown to exhibit the highest promoter activities in two immortalized human granulosa-luteal cell lines, SVOG-4o and SVOG-4m. Two putative CCAAT/enhancer binding protein (C/EBP) motifs and one GATA motif were identified within this region. Mutational studies showed that these three motifs cooperated synergistically to regulate GnRHR gene transcription in the granulosa cells but not in other cell types including human ovarian carcinoma OVCAR-3, human embryonic kidney-293 (HEK-293) and mouse pituitary gonadotrope-derived αT3–1 cells. Surprisingly, by competitive EMSAs, we found that an Oct-1 consensus sequence was able to inhibit protein complex formation with the distal C/EBP motif, suggesting a possible cross-talk between the Oct-1 transcription factor and this C/EBP motif. Taken together, our results strongly indicate a role of the C/EBP and GATA motifs in regulating GnRHR gene transcription in human granulosa-luteal cells and further suggest that tissue-specific expression of human GnRHR gene is mediated by differential promoter usage.
11β-Hydroxysteroid Dehydrogenase Type 1 and Its Role in the Hypothalamus-Pituitary-Adrenal Axis, Metabolic Syndrome, and Inflammation
Authors: Cooper Mark S. , Stewart Paul M. 
Published: January 2014

ABSTRACT

Context
11β-Hydroxysteroid dehydrogenase (11β-HSD) enzymes are now appreciated to be important regulators of hormone action at a tissue level. 11β-HSD1 is widely expressed and increases glucocorticoid action through its unique ability to convert inactive glucocorticoids (cortisone in man, 11-dehydrocorticosterone in rodents) to their active forms (cortisol and corticosterone, respectively). The enzyme has roles in the normal hypothalamus-pituitary-adrenal (HPA) axis, has been implicated in metabolic syndrome, and may modulate various aspects of the immune response.

Evidence Acquisition
A review of published, peer-reviewed medical literature (1990 to June 2009) on the physiology and pathophysiology of 11β-HSD1 was performed with an emphasis on HPA axis consequences, the metabolic syndrome, and the inflammatory response.

Evidence Synthesis
Studies of patients with genetic defects in 11β-HSD1 action show abnormal HPA axis responses with hyperandrogenism being a major consequence. The mechanisms underlying these abnormalities have been explored in mouse models with targeted deletion of components of the 11β-HSD1 system. A range of experimental studies emphasize the role of 11β-HSD1 in the metabolic syndrome and the potential for treatment with chemical inhibitors. An emerging area is the role of 11β-HSD1 in the inflammatory response.

Conclusions
11β-HSD1 activity is an important component of the HPA axis and contributes to the metabolic syndrome and the normal immune response. Ongoing clinical observations and the development of selective inhibitors will further clarify the role of 11β-HSD1 in these areas.