bluuebunny/crossref_metadata_2025_split huggingface dataset:
Selective Involvement of Interleukin-6 in the Transcriptional Activation of the Suppressor of Cytokine Signaling-3 in the Brain during Systemic Immune Challenges*
Authors: LeBel Éric , Vallières Luc , Rivest Serge 
Published: January 2014

AbstractCytokine-inducible proteins named as suppressors of cytokine signaling (SOCS) are rapidly induced by interleukin-6 (IL-6) and other members sharing the gp130 receptor subunit after activation of the Janus kinases (JAK) and the signal transducers and activators of transcription (STAT). These inhibitory proteins generally prevent tyrosine phosphorylation of IL-6 receptor signaling subunit gp130, specific JAK and STAT or in acting at steps distal to JAK activation. Expression of these inhibitory proteins is therefore a useful tool to investigate the signaling events occurring in the brain during immunogenic stimuli that involve cytokines of the IL-6 family. This study investigated the effect of ip lipopolysaccharide (LPS) administration on the expression of one key member of the SOCS family, SOCS-3, in both rats and mice. In rats, the endotoxin caused a profound transcriptional activation of the inhibitory factor in the circumventricular organs subfornical organ, organum vasculosum of the lamina terminalis, arcuate nucleus/median eminence, area postrema, choroid plexus, leptomeninges, ependymal lining cells, and along the endothelium of the brain blood vessels. The hybridization signal for SOCS-3 messenger RNA was low at 1 h, but robust at 3 and 6 h and declined to return to basal levels 12 h after the single ip LPS injection. The pattern of SOCS-3 expression was similar in the brain of wild-type mice, although induction of the inhibitory factor was no longer observed in the ependymal lining cells of the cerebral ventricles and the blood microvessels of IL-6-deficient animals at all the times evaluated, i.e. from 1–8 h post-LPS injection. The endothelium of the brain capillaries also exhibited up-regulation of both IL-6 receptor and gp130 subunits during systemic inflammation, which allowed SOCS-3 expression in response to circulating IL-6. The present data indicate that the JAK/STAT transduction pathways that lead to SOCS-3 transcription are activated within cells accessible from the blood circulation, but not within deep parenchymal elements of the brain during endotoxemia. Induction of SOCS-3 followed the cascade of events that take place during the acute phase response and the contribution of IL-6 in activating the inhibitory factor is site specific and not generalized throughout the central nervous system.
Leptin Deficiency Induced by Fasting Impairs the Satiety Response to Cholecystokinin**This work was supported by grants from the NIH (DK-12829, DK-52989, and NS-32272) and by the Royalty Research Fund, the Diabetes Endocrinology Research Center, and the Clinical Nutrition Research Unit of the University of Washington.
Authors: McMinn Julie E. , Sindelar Dana K. , Havel Peter J. , Schwartz Michael W. 
Published: January 2014

Abstract
Leptin administration potentiates the satiety response to signals such as cholecystokinin (CCK), that are released from the gut during a meal. To investigate the physiological relevance of this observation, we hypothesized that leptin deficiency, induced by fasting, attenuates the satiety response to CCK. To test this hypothesis, 48-h-fasted or fed rats were injected with ip saline or CCK. Fasting blunted the satiety response to 3.0 μg/kg CCK, such that 30-min food intake was suppressed by 65.1% (relative to saline-treated controls) in fasted rats vs. 85.9% in the fed state (P&lt; 0.05). In a subsequent experiment, rats were divided into three groups: 1) vehicle/fed; 2) vehicle/fasted; and 3) leptin-replaced/fasted; and each group received 3.0 μg/kg ip CCK. As expected, the satiety response to CCK was attenuated by fasting in vehicle-treated rats (30-min food intake: vehicle/fed, 0.3 ± 0.1 g; vehicle/fasted, 1.7 ± 0.4 g; P &lt; 0.01), and this effect was prevented by leptin replacement (0.7 ± 0.2 g, P &lt; 0.05 vs. vehicle/fasted; P = not significant vs. vehicle/fed). To investigate whether elevated neuropeptide Y (NPY) signaling plays a role in the effect of leptin deficiency to impair the response to CCK, we measured the response to 3.0 μg/kg ip CCK after treatment with 7.5 μg intracerebroventricular NPY. We found that both CCK-induced satiety and its ability to increase c-Fos-like-immunoreactivity in key brainstem-feeding centers were attenuated by NPY pretreatment. We conclude that an attenuated response to meal-related satiety signals is triggered by leptin deficiency and may contribute to increased food intake.
Selective Impairment of Corticotropin-Releasing Factor1 (CRF1) Receptor-Mediated Function Using CRF Coupled to Saporin1
Authors: Maciejewski-Lenoir Dominique , Heinrichs Steve C. , Liu Xin-Jun , Ling Nicholas , Tucker Anh , Xie Qiu , Lappi Douglas A. , Grigoriadis Dimitri E. 
Published: January 2014

AbstractCRF is the main component in the brain neuropeptide effector system responsible for the behavioral, endocrine, and physiological activation that accompanies stress activation. Reduced CRF system activation plays a role in the etiology of a variety of psychiatric and metabolic disease states. We have developed a novel protein conjugate that joins native rat/human CRF to a ribosome-inactivating protein, saporin (CRF-SAP), for the purpose of targeted inactivation of CRF receptor-expressing cells. Cytotoxicity measurements revealed that CRF-SAP (1–100 nm) produced concentration-dependent and progressive cell death over time in CRF1 receptor-transfected L cells, but at similar concentrations had no effect on CRF2α receptor-transfected cells. The CRF-SAP-induced toxicity in CRF1-transfected cells was prevented by coincubation with the competitive CRF1/CRF2 receptor peptide antagonist,[ d-Phe12]CRF-(12–41), or the selective nonpeptide CRF1 receptor antagonist, NBI 27914. Finally, in cultured rat pituitary cells that express native CRF1 receptors, CRF-SAP suppressed CRF-induced (1 nm) ACTH release. GnRH (1–10 nm) stimulated LH release was also assessed in the same pituitary cultures. Although there was a slight decrease in LH release from these cultures, this decrease was observed with CRF-SAP or SAP alone, suggesting that the response was nonspecific. Taken together, these results suggest the utility of CRF-SAP as a specific and subtype-selective tool for long term impairment of CRF1 receptor-expressing cells.
Activin A-Induced HepG2 Liver Cell Apoptosis: Involvement of Activin Receptors and Smad Proteins*
Authors: Chen Wei , Woodruff Teresa K. , Mayo Kelly E. 
Published: January 2014

Abstract
A balance between cell proliferation and apoptosis is important for regulating normal liver function. Proteins of the transforming growth factor-β superfamily are known to be important mediators of apoptosis in the liver. In this study we demonstrate that activin A potently induces apoptotic cell death in a hepatoma cell line, HepG2 cells. To determine the roles of activin receptors and downstream signaling proteins in activin A-induced apoptosis in these cells, the activin signaling pathway was analyzed using the transcription of an activin-responsive reporter gene, p3TP-Lux, as an assay. Although individual activin receptors had little effect on transcriptional activity, coexpression of an activin type I receptor and a type II receptor significantly increased both basal and activin-induced transcriptional activation, with the combination of receptors IB and IIB being the most potent. Similarly, expression of individual Smad proteins had only a modest effect on reporter gene activity, but the combination of Smad2 and Smad4 strongly stimulated transcription. Activin signaling induced a rapid relocation of Smad2 to the nucleus, as determined using a green fluorescence protein-Smad2 fusion protein. In contrast, green fluorescence protein-Smad4 remained localized to the cytoplasm unless it was coexpressed with Smad2. In agreement with the transcriptional response assays, overexpression or suppression of activin signaling components in HepG2 cells altered apoptosis. Overexpression of receptors IB and IIB or Smad proteins 2 and 4 stimulated apoptosis, whereas dominant negative mutant forms of the activin type IIB receptor or Smad2 blocked activin-stimulated apoptosis. These studies suggest that signaling from the cell surface to the nucleus through Smad proteins is a required component of the activin A-induced cell death process in liver cells.
Nitric Oxide and Carbon Monoxide Have a Stimulatory Role in the Hypothalamic-Pituitary-Adrenal Response to Physico-Emotional Stressors in Rats*
Authors: Kim C. Kwon , Rivier Catherine L. 
Published: January 2014

AbstractWe tested the hypothesis that nitric oxide and carbon monoxide, which are produced in the brain by nitric oxide synthase (NOS) and heme oxygenase (HO), modulate the hypothalamic-pituitary-adrenal response to physico-emotional stressors by acting at the hypothalamus. Accordingly, we determined 1) whether the intracerebroventricular (icv) injection of NOS or HO inhibitors at doses that were confined to the brain attenuated electroshock-induced ACTH release; and 2) whether the decreases in this ACTH response were concurrent with decreases in NOS or HO activity levels at the hypothalamus. Icv injection of the NOS inhibitor Nω-nitro-l-arginine-methylester (L-NAME; 50 μg) or the HO inhibitor tin protoporphyrin (SnPP; 20–25μ g) significantly blunted the plasma ACTH response to a 45-min session of intermittent electroshocks. Importantly, in these same animals there were concurrent decreases in hypothalamic NOS or HO activities, respectively. There were little or no effects of these inhibitors on anterior pituitary NOS or HO activities, indicating that there was only minimal leakage of the drug from the brain after icv administration. The specificity of action of these inhibitors was confirmed by the fact that SnPP did not affect NOS activity, and L-NAME did not affect HO activity. Finally, L-NAME produced no effect, whereas SnPP produced only transient increases in blood pressure, suggesting that these inhibitors do not affect activity indirectly through alterations in blood pressure. These data support the hypothesis that in the whole animal, both NO and CO exert a stimulatory influence on the acute ACTH response to physico-emotional stressors, and that the hypothalamus is the critical site of their actions.
Testosterone Effect on Insulin Content, Messenger Ribonucleic Acid Levels, Promoter Activity, and Secretion in the Rat*
Authors: Morimoto Sumiko , Fernandez-Mejia Cristina , Romero-Navarro Guillermo , Morales-Peza Nestor , DÍaz-Sánchez Vicente 
Published: January 2014

AbstractCoexistence of hyperinsulinemia and hyperandrogenism in women has been frequently described. Most of the studies addressing this issue have focused on the mechanisms by which insulin produces hyperandrogenism. In the present study, we analyzed the effects of testosterone in vivo and in vitro upon insulin gene expression and release in the rat. Our studies demonstrate that testosterone increases insulin messenger RNA (mRNA) levels in vitro as well as in vivo. In both prepuberal and intact adult rats, serum testosterone concentrations were positively correlated with insulin mRNA levels and insulin concentration in serum. Testosterone deprivation after gonadectomy decreased both insulin gene expression and serum insulin concentration. Insulin mRNA levels were partially restored after 3 days of testosterone administration and serum insulin was 80% and 27% above baseline values at 5 and 7 days posttreatment. Primary cultured pancreatic islets treated with the sexual steroid increased about 80% insulin mRNA, as well as protein, and release. In transfected islets, testosterone increased the activity of the −410 bp rat insulin promoter I by 154%. These data demonstrate that testosterone has a direct effect upon pancreatic islet function by favoring insulin gene expression and release.
High-Level Expression of a Functional Single-Chain Human Chorionic Gonadotropin-Luteinizing Hormone Receptor Ectodomain Complex in Insect Cells*
Authors: Fralish Gregory B. , Narayan Prema , Puett David 
Published: January 2014

AbstractReproductive capacity in primates is dependent on the high-affinity binding of the glycoprotein hormones LH and human (h)CG to the large ectodomain (ECD) of their common receptor (LHR). Our understanding of the precise molecular determinants of hormone binding is limited, because there are no structural data for any of the glycoprotein hormone receptors. Overexpression of the ECD of the receptor has been attempted in various expression systems. Prokaryotic expression does not yield properly folded ECD. Eukaryotic expression, on the other hand, results in mostly heterogeneous, intracellularly trapped protein, but the secreted ECD is completely folded. Accordingly, we have tethered the single-chain hormone, yoked hCG, to the N terminus of LHR-ECD (yoked hormone-extracellular domain). Yoked hCG is secreted at high levels; binds LHR with high affinity; and, when tethered to the N terminus of full-length LHR, it binds and constitutively activates the receptor. Using recombinant baculovirus, yoked hormone-extracellular domain is secreted from insect cells at levels greater than 1 μg/ml, nearly 20-fold higher than that previously reported in eukaryotic expression systems. The protein was purified and binds exogenous 125I-hCG with high affinity but, significantly, only after protease treatment to remove the tethered hormone. Thus, the fusion protein seems to form a functional hormone-receptor complex that is expressed at levels sufficient for its biophysical characterization.
Cycles of Transcription and Translation Do Not Comprise the Gonadotropin-Releasing Hormone Pulse Generator in GT1 Cells*
Authors: Pitts Gilbert R. , Nunemaker Craig S. , Moenter Suzanne M. 
Published: January 2014

Abstract
Neural control of reproduction is achieved through episodic GnRH secretion, but little is known about the molecular mechanisms underlying pulse generation. The ultradian time domain of GnRH release suggests mechanisms ranging from macromolecular synthesis to posttranslational modification could be involved. We tested if messenger RNA (mRNA) or protein synthesis are components of the pulse generator by determining the effects of transcription and translation inhibitors on episodic GnRH release from immortalized GT1–1 GnRH neurons. Time course and efficacy of transcription and translation blockade were assessed by determining the ability of specific inhibitors to block the robust, rapid induction of c-fos mRNA or protein accumulation by forskolin (10 μm). The transcription inhibitors actinomycin D (ACT-D, 20 μm) or 5,6-dichlorobenzimidazole riboside (DRB, 100 μm), or the translation inhibitors anisomycin (ANI, 10 μm) or puromycin (PUR, 10 μm) were applied to GT1–1 cells 30, 15, or 0 min before forskolin. Northern and Western blots revealed blockade of transcription and translation was rapid and essentially complete. GT1–1 cells were perifused for a 90- to 120-min control period then for 100–130 min with vehicle or inhibitor to examine pulsatile GnRH secretion. GnRH interpeak intervals, peak amplitude, and peak area were not different between control and experimental periods of cells treated with vehicle (n = 15), ACT-D (n = 10), DRB (n = 6), ANI (n = 8), and PUR (n = 6; P &gt; 0.05). This study presents the first clear evidence that the series of reactions resulting in secretion of a GnRH pulse do not include cycles of transcription and translation. Although these mechanisms would be required to replenish components of the pulse generator, they are not integral components of this oscillator. We hypothesize that posttranslational events underlie episodic GnRH release in GT1–1 cells.
Mitogenic and Metabolic Effects of Type I IGF Receptor Overexpression in Insulin Receptor-Deficient Hepatocytes
Authors: Kim Jane J. , Park Byung-Chul , Kido Yoshiaki , Accili Domenico 
Published: January 2014

AbstractWe have previously shown that hepatocytes lacking insulin receptors (Ir−/−) fail to mediate metabolic responses, such as stimulation of glycogen synthesis, while retaining the ability to proliferate in response to IGFs. In this study we have asked whether overexpression of type I IGF receptors would rescue the metabolic response of Ir−/− hepatocytes. After IGF-I stimulation, insulin receptor substrate-1 and -2 phosphorylation and PI3K activity were restored to levels similar to or greater than those seen in wild-type cells. Rates of cell proliferation in response to IGF-I increased approximately 2-fold, whereas glycogen synthesis was restored to wild-type levels, but was comparatively smaller than that elicited by overexpression of insulin receptors. In summary, overexpression of IGF-I receptors in Ir−/− hepatocytes normalized insulin receptor substrate-2 phosphorylation and glycogen synthesis to wild-type levels, whereas it increased cell proliferation above wild-type levels. Moreover, stimulation of glycogen synthesis was submaximal compared with the effect of insulin receptor overexpression. We conclude that IGF-I receptors are more efficiently coupled to cell proliferation than insulin receptors, but are less potent than insulin receptors in stimulating glycogen synthesis. The data are consistent with the possibility that there exist intrinsic signaling differences between insulin and IGF-I receptors.
Parathyroid Hormone Inhibits c-Jun N-Terminal Kinase Activity in Rat Osteoblastic Cells by a Protein Kinase A-Dependent Pathway
Authors: Doggett Teresa A. , Swarthout John T. , Jefcoat Stephen C. , Wilhelm Dagmar , Dieckmann Andreas , Angel Peter , Partridge Nicola C. 
Published: January 2014

AbstractTreatment of osteoblastic cells with PTH initiates dual signaling cascades resulting in activation of both PKA and PKC. It has been shown that PTH either inhibits or stimulates ERKs depending on dose of the hormone; nevertheless, the ability of PTH to regulate other members of the MAPK family is unknown. Another member of this family, c-Jun-NH2-terminal kinase (JNK), is preferentially activated by cytokines and cellular stresses and plays a key role in regulating the activity of various transcription factors. We demonstrate that treatment of UMR 106-01 cells and rat calvarial osteoblasts with PTH (10−8m), N-terminal peptides of PTH that selectively activate PKA, or 8-bromo-cAMP (activates PKA) results in the inhibition of JNK activity from high basal levels. Examination of the upstream members of the JNK cascade revealed that both stress-activated protein kinase/extracellular signal-related kinase kinase 1/MAPK kinase 4 and MAPK/extracellular signal-related kinase kinase kinase 1 activities were also inhibited after treatment with PTH (10−8m). We conclude that treatment of osteoblastic cells with PTH is sufficient to inhibit high basal JNK activity by activation of the PKA signaling cascade.
The Role of Insulin-Like Growth Factor (IGF) Binding Protein-2 in the Insulin-Mediated Decrease in IGF-I Bioactivity
Authors: Arafat Ayman M. , Weickert Martin O. , Frystyk Jan , Spranger Joachim , Schöfl Christof , Möhlig Matthias , Pfeiffer Andreas F.H. 
Published: January 2014

ABSTRACT

Context:
Insulin interacts with the GH-IGF system by a reciprocal regulation of IGF-binding proteins (IGFBP) and GH, which in turn regulate insulin sensitivity via bioactive IGF-I. This network is linked to metabolic syndrome and cardiovascular diseases.

Objective:
We evaluated the effect of glucose and insulin on IGFBP-1-4, particularly IGFBP-2, in the regulation of bioactive IGF-I and its relation to insulin resistance.

Setting:
The study was conducted at an endocrinology center.

Research Design and Methods:
Twenty-four healthy subjects (12 men; aged 21–72 yr; body mass index 25.9 ± 0.9 kg/m2) and 19 subjects with impaired glucose tolerance (IGT; eight men; aged 26–71 yr; body mass index 28.9 ± 1.2 kg/m2 ) were prospectively studied using oral glucose tolerance test and hyperinsulinemic euglycemic clamp.

Results:
During the clamp, insulin decreased IGF-I bioactivity in both IGT subjects and controls (−16.2 ± 2.8 and −13.9 ± 3.3%, respectively; P &lt; 0.01). In addition, insulin increased IGFBP-2 and GH and decreased IGFBP-1 and -4 but did not alter total IGF-I, IGF-II, or IGFBP-3 levels. During the oral glucose tolerance test, GH and IGFBP-1 were markedly suppressed. Subjects with IGT showed more pronounced insulin resistance and lower GH, IGFBP-1, and IGFBP-2 levels (P &lt; 0.05). In multiple regression analysis, IGFBP-2 was an independent predictor of insulin sensitivity (β = 0.36, P &lt; 0.05) and IGF-I bioactivity (β = −0.5, P &lt; 0.05).

Conclusions:
Our data indicate that insulin acutely decreases IGF-I bioactivity through differential modulation of IGFBPs. Furthermore, IGFBP-2 plays a central role in the insulin-IGF system cross talk and is closely linked to insulin resistance, thereby providing a further explanation for its association with the metabolic syndrome.
Molecular Scanning of β-3-Adrenergic Receptor Gene in Total Congenital Lipoatrophic Diabetes Mellitus*
Authors: Silver Kristi , Walston Jeremy , Plotnick Leslie , Taylor Simeon I. , Kahn C. Ronald , Shuldiner Alan R. 
Published: January 2014

Abstract
Total congenital lipoatrophic diabetes is characterized by absence of subcutaneous adipose tissue, hypertriglyceridemia, and insulin resistance. We hypothesized that mutations in the β-3-adrenergic receptor (β3AR) gene might result in the lipoatrophic phenotype by preventing triglyceride storage in adipocytes; thereby, resulting in secondary insulin resistance. We screened the β3AR gene in 7 subjects with total congenital lipoatropic diabetes. We found a heterozygous substitution of a guanine to cytosine at position −153 (G-153C) in the 5′-untranslated region of 3 African-American lipoatrophic siblings and 1 sibling without lipoatrophy but with insulin resistance. To determine whether the base change was related to the lipoatrophic phenotype, we genotyped 69 African-Americans without lipoatrophy and found the G-153C substitution in 2 control subjects (allele frequency = 0.01). No other single-stranded polymorphism variants were found in any of the 7 lipoatrophic subjects. Direct sequencing of both alleles of 1 lipoatrophic subject demonstrated a thymidine insertion at position− 300 in both alleles. All lipoatrophic subjects along with 20 African-American control subjects were homozygous for the base insertion, suggesting an error in the published sequence. In conclusion, mutations in the β3AR gene do not appear to be involved in the development of congenital total lipoatrophy.