bluuebunny/crossref_metadata_2025_split huggingface dataset:
Thyroid Hormone Controls the Expression of Insulin-Like Growth Factor I Receptor Gene at Different Levels in Lung and Heart of Developing and Adult Rats*
Authors: Moreno Beatriz , Rodríguez-Manzaneque Juan Carlos , Pérez-Castillo Ana , Santos Angel 
Published: January 2014

AbstractThyroid hormone exerts profound effects on the insulin-like growth factors (IGFs)/IGF factor I receptor (IGF-IR) system through its action on the production of IGF-I peptide and IGF-binding proteins. Most of these actions are mediated by the direct control of pituitary GH gene by thyroid hormone. In this work, we have analyzed the possible effect of hypothyroidism on the expression of IGF-IR gene, both in adult and developing animals. Our results show that in the lung and heart, thyroid hormone exerts a negative effect on IGF-IR gene expression in the adult animals and during perinatal life (from day 15 onwards). This negative effect is exerted at different levels. In the heart, this regulation occurs at a pretranslational level, indicated by the fact that parallel changes in the number of membrane IGF-I receptors and IGF-IR transcripts were observed, whereas in lung, no effect of thyroid hormone was noted in the amount of IGF-IR transcripts, suggesting a translational or posttranslational control. GH does not seem to mediate T3 effects on this gene. In contrast, retinoic acid increases the expression of IGF-IR gene at a transcriptional or posttranscriptional level in adult lung and heart. Because the IGFs/IGF-IR system is depressed in hypothyroid animals, the specific increase in the number of IGF-IRs in the lung and heart of these animals could represent a mechanism to ameliorate the negative effects of hypothyroidism on these important organs.
Regulation of Rat Testis Gonocyte Proliferation by Platelet-Derived Growth Factor and Estradiol: Identification of Signaling Mechanisms Involved*
Authors: Li Hua , Papadopoulos Vassilios , Vidic Branislav , Dym Martin , Culty Martine 
Published: January 2014

AbstractTo determine what factors regulate gonocyte proliferation in newborn rats, we first examined the expression of several signal transduction molecules by immunocytochemistry in 3-day-old rat testis sections. We found that gonocytes specifically expressed the ι and ζ isoforms of protein kinase (PK) C (PKC) and the phosphatidylinositol 3-kinase (PI 3-K). Because both the ζPKC and PI 3-K have been shown to play a role in platelet-derived growth factor (PDGF)-induced cell proliferation, we examined the effects of PDGF on gonocytes. For this, we developed a method to obtain highly purified and viable gonocytes in culture. After enzymatic digestion, differential adhesion, and two successive gradient fractionations, the gonocyte suspension obtained was over 90% pure, as assessed by light microscopy. The viability of cultured gonocytes exceeded 90% after 48 h in the presence of 2.5% FBS used as a survival factor. Immunodetection studies showed that isolated gonocytes expressed ζPKC, PI 3-K, and the PDGF receptor. Treatment with 10 ng/ml PDGF induced a 4-fold increase of bromodeoxyuridine incorporation into gonocytes (from 5% proliferative gonocytes under basal conditions to 20% in the presence of PDGF). Because neonatal Sertoli cells secrete high levels of the growth promoting steroid, 17β-estradiol, we also tested its effect and found that it induced gonocyte proliferation at a level comparable with that of PDGF and that this effect was blocked by the estrogen receptor antagonist, ICI 164384. The combination of PDGF and estradiol, however, was not additive, suggesting that their effects were mediated by common molecular target(s). These results demonstrate that PDGF and estradiol activate gonocyte proliferation in vitro, suggesting that they may act as the physiological regulators of gonocyte development in vivo.
Integrin Binding to Immobilized Collagen and Fibronectin Stimulates the Proliferation of Human Thyroid Cells in Culture*
Authors: Vitale Mario , Illario Maddalena , Di Matola Tiziana , Casamassima Adele , Fenzi Gianfranco , Rossi Guido 
Published: January 2014

AbstractThe expression of integrins of the β1 family and their possible biological effects were investigated in normal human thyroid cells in monolayer culture. The expression of β1 andα 1–6 integrin subunits was determined by flow cytofluorometry with specific antibodies. Follicular cells of subconfluent monolayer cultures expressedα 2β1 and α3β1 at high levels, while α1β1 was only slightly expressed, and α4β1,α 5β1, and α6β1 were never detected. Cell attachment assays were performed in fibronectin-, type I collagen-, and laminin-coated microtiter plates. Thyroid cells, while adherent to collagen and fibronectin, showed poor attachment to laminin despite the abundance of their putative receptorsα 2β1 and α3β1. In serum-free medium, collagen and fibronectin induced cytoskeletal organization, change of cell shape from round to flat, and cell spreading. [3H]Thymidine incorporation and proliferation assays were used to evaluate the effects of collagen and fibronectin on DNA synthesis and cell growth in the absence of a change in spreading or cell shape. Both substrates, in low serum-containing medium, induced a concentration-dependent increase in [3H]thymidine incorporation partially inhibited by RGD-containing peptides that blocked the cell attachment.Thyrocytes cultured in low serum-containing medium on immobilized fibronectin or collagen showed a dose-dependent stimulation of proliferation. These data indicate that fibronectin and collagen can regulate the cytoskeletal organization and cell shape and stimulate the proliferation of normal human thyroid cells in culture and that integrins mediate these effects of extracellular matrix proteins.
Prolactin Regulation of Islet-Derived INS-1 Cells: Characteristics and Immunocytochemical Analysis of STAT5 Translocation*
Authors: Stout L. E. , Svensson A. M. , Sorenson R. L. 
Published: January 2014

AbstractThe major changes in pancreatic islet function during pregnancy and after exposure to lactogens are an increase in β-cell proliferation and enhanced insulin secretion. In this study we examined INS-1 cells as a potential model for further inquiry into PRL signaling inβ -cells. Proliferation of β-cells, insulin secretion, and quantitative immunocytochemical analysis of STAT5 translocation were studied.PRL treatment of INS-1 cells resulted in a 2- to 4-fold increase in cell proliferation compared to that in the control group. In contrast, there was no effect of PRL treatment on HIT cell proliferation and only a very small effect on RIN cell proliferation. A significant effect on INS-1 cell proliferation was observed at 10 ng/ml and reached a maximum at 200 ng/ml.PRL treatment resulted in enhanced insulin secretion from INS-1 cells. There was a time-dependent increase in insulin secretion, which when corrected for cell number was 1.5-fold greater in the PRL-treated cells. The effects of PRL on cell division and insulin secretion were glucose dependent.The presence of the JAK family of tyrosine kinases and the transcription factor STAT5 in INS-1 cells was examined by immunocytochemical techniques. Although all members of the JAK family of kinases were detected, the staining intensity of JAK-2 was noticeably more intense. Initial studies of STAT5 translocation were performed using PRL-dependent Nb2 lymphoma cells, in which PRL treatment resulted in a nearly complete translocation of cytoplasmic STAT5 to the nucleus. Under control conditions there was a near-equal fluorescence intensity of STAT5 staining in the nucleus and cytoplasm of INS-1 cells. PRL treatment resulted in a time-dependent increase in STAT5 staining in the nucleus, with a corresponding decrease in the cytoplasm. The STAT5 staining intensity in the nucleus remained elevated for the duration of PRL treatment. This effect was reversible upon removal of PRL from the medium. Besides PRL, both GH and FBS induced a similar translocation of STAT5 to the nucleus. Although present in RIN cells, no detectable changes in STAT5 were observed in RIN cells after exposure to PRL, GH, or FBS.INS-1 cells should provide a good model for further inquiry into the intracellular signaling pathways used by PRL and how these events alter islet function.
Interleukin-3 and Interleukin-6 Stimulate Cortisol Secretion from Adult Human Adrenocortical Cells
Authors: Weber M. M. , Michl P. , Auernhammer C. J. , Engelhardt D. 
Published: January 2014

Abstract
Accumulating data indicate that interleukins can activate the hypothalamic-pituitary-adrenal (HPA) axis. We evaluated the effect of human recombinant interleukin-3 (IL-3) and interleukin-6 (IL-6) on cortisol secretion from adult human adrenocortical cells in primary culture. IL-3 and IL-6 (100 μg/L) equipotently stimulated basal cortisol secretion approximately 5-fold. The stimulatory effect was significant after 12 h (p &lt; 0.01) and maximum cortisol levels were induced after 48 h. In contrast to ACTH, which significantly induced cAMP levels in parallel to its steroidogenic effect, IL-3 or IL-6 had no significant effect on cAMP. Furthermore, we showed that specific inhibition of the cyclooxygenase pathway by indomethacin completely blocked the steroidogenic effect of IL-6 while the effect of IL-3 was not affected. In contrast, coincubation with nordihydroguaiaretic acid—a specific inhibitor of the lipoxygenase system—abolished IL-3 stimulated steroidogenesis but had no effect on IL-6 stimulated cortisol secretion. These findings indicate that IL-3 and Il-6 directly stimulate the steroidogenesis at the adrenal level through activation of different, cAMP-independent pathways. While the stimulatory effect of IL-6 on cortisol secretion from adult human adrenocortical cells seems to be mediated through the cyclooxygenase pathway, the effect of IL-3 on adrenocortical cortisol secretion is dependent on the lipoxygenase pathway.
Cyclic Adenosine 3′,5′-Monophosphate Regulates GLUT4 and GLUT1 Glucose Transporter Expression and Stimulates Transcriptional Activity of the GLUT1 Promoter in Muscle Cells*
Authors: Viñals Francesc , Ferré Josep , Fandos César , Santalucia Tomàs , Testar Xavier , Palacín Manuel , Zorzano Antonio 
Published: January 2014

AbstractWe have previously reported that innervation-dependent basal contractile activity regulates in an inverse manner the expression of GLUT1 and GLUT4 glucose transporters in skeletal muscle. Based on the facts that muscle innervation decreases and muscle denervation increases cAMP levels, we investigated whether cAMP might mediate the effects of innervation/denervation on glucose transporter expression. Treatment of L6E9 myotubes with 8-bromo-cAMP, forskolin, or monobutyryl-8-bromo-cAMP led to a marked decrease in GLUT4 protein levels; 8-bromo-cAMP also diminished GLUT4 messenger RNA (mRNA), suggesting pretranslational repression. In contrast, L6E9 myoblasts and myotubes responded to 8-bromo-cAMP or forskolin by increasing the cell content of GLUT1 protein. Induction of GLUT1 protein was a consequence of the activation of different mechanisms in myoblast and myotube cells; whereas 8-bromo-cAMP treatment caused a substantial increase in GLUT1 mRNA in myoblasts, no change in GLUT1 mRNA was detected in myotubes. The increase in GLUT1 mRNA in L6E9 myoblasts induced by 8-bromo-cAMP was the result of transcriptional activation, as concluded from transfection analysis of 2.1 kilobases of the rat GLUT1 gene promoter fused to the bacterial chloramphenicol acetyltransferase gene. Furthermore, the stimulatory effect of 8-bromo-cAMP on the transcriptional activity of the GLUT1 promoter required a 33-bp sequence lying 5′ upstream of the transcription start site. In all, cAMP inversely regulates GLUT4 and GLUT1 glucose transporter expression in muscle cells. Furthermore, our results suggest that down-regulation of GLUT4 expression and up-regulation of GLUT1 expression in muscle associated with denervation are partly attributable to cAMP.
Insulin-Like Growth Factor Binding Protein-5 Binds to Plasminogen Activator Inhibitor-I*
Authors: Nam Taek Jeong , Busby Walker , Clemmons David R. 
Published: January 2014

AbstractInsulin-like growth factor binding protein-5 (IGFBP-5) has been shown to bind to the extracellular matrix (ECM) of both fibroblasts and smooth muscle cells. The ECM-IGFBP-5 interaction is mediated in part by binding to heparan sulfate containing proteoglycans. Because proteoglycans may not be the only components of ECM that bind to IGFBP-5, we have determined its ability to bind to other ECM proteins. When a partially purified mixture of the proteins that were present in fibroblast conditioned medium was purified by IGFBP-5 affinity chromatography, a 55-kDa protein was eluted. Amino acid sequencing of the amino terminal 28 amino acids showed that it was human plasminogen activator inhibitor-1 (PAI-1). To determine if this interaction was specific, purified human PAI-1 was incubated with IGFBP-5 and the IGFBP-5/PAI-1 complex immunoprecipitated with anti-PAI-1 antiserum. When the precipitate was analyzed by immunoblotting using anti-IGFBP-5 antiserum, the intensity of the IGFBP-5 band was substantially increased compared with controls that did not contain human PAI-1. A synthetic IGFBP-5 peptide that contained the amino acid sequence between positions 201 and 218 inhibited IGFBP-5/PAI-1 interaction. Coincubation of IGFBP-5 mutants that contained substitutions for specific basic residues located between positions 201 and 218 with PAI-1 indicated that some of these amino acids were important for binding. Two mutants that contained neutral substitutions for specific basic amino acids within the glycosaminoglycan binding domain had reduced binding to PAI-1. In contrast, three other mutants that also had substitutions for charged residues in the same region had no reduction in binding. Heparin and heparan sulfate inhibited the IGFBP-5/PAI-1 interaction; however, several other glycosaminoglycans had no effect. PAI-1 was determined to be an important ECM component for binding because approximately 27% of total ECM binding could be inhibited with anti-PAI-1 antiserum. Competitive binding studies with unlabeled IGFBP-5 showed that the dissociation constant of PAI-1 for IGFBP-5 was 9.1 × 10−8m. In summary, IGFBP-5 binds specifically to plasminogen activator inhibitor-1. Because this is present in the extracellular matrix of several cell types, it may be one of the important binding components of ECM. PAI-1 binding partially protects IGFBP-5 from proteolysis, suggesting that it is one of the ECM components that is involved in mediating this effect.
1α,25-Dihydroxyvitamin D3 Actions in LNCaP Human Prostate Cancer Cells Are Androgen-Dependent*
Authors: Zhao Xiao-Yan , Ly Lan H. , Peehl Donna M. , Feldman David 
Published: January 2014

Abstract
We and others have recently shown that 1α,25-dihydroxyvitamin D3 [1,25-(OH)2D3] significantly inhibits cell proliferation and increases secretion of prostate-specific antigen (PSA) in LNCaP cells, an androgen-responsive human prostate cancer cell line. The present study was designed to investigate the possible interactions between 1,25-(OH)2D3 and androgens in the regulation of LNCaP cellular function. LNCaP cell growth was dose-dependently inhibited by 1,25-(OH)2D3 (60% inhibition at 10 nm) when cells were cultured in medium supplemented with FBS (FBS medium). 1,25-(OH)2D3-treated cells showed a 5-fold increase in PSA secretion, similar to the increase seen in dihydrotestosterone (DHT)-treated cells. In combination, 1,25-(OH)2D3 and DHT synergistically enhanced PSA secretion 22-fold. This synergistic effect was even greater when cells were cultured in medium supplemented with charcoal-stripped serum (CSS medium), where endogenous steroids are substantially depleted. Under these conditions, 1,25-(OH)2D3 and DHT together stimulated PSA secretion up to 50-fold over the untreated control. Radioligand binding assays and Western blot analyses showed that the androgen receptor (AR) content was increased significantly by 1,25-(OH)2D3 at 48 h. Furthermore, the steady-state mRNA level of AR was up-regulated approximately 2-fold by 1,25-(OH)2D3 at 24 h. When cells were grown in CSS medium, 1,25-(OH)2D3 alone no longer inhibited cell growth or induced PSA secretion. Titration experiments revealed that the addition of DHT at 1 nm to the medium restored the antiproliferative activity of 1,25-(OH)2D3. Conversely, an antiandrogen, Casodex, completely blocked 1,25-(OH)2D3 antiproliferative and PSA stimulation activities when cells were cultured in FBS medium. In conclusion, these results demonstrate that the antiproliferative and PSA induction activities of 1,25-(OH)2D3 in LNCaP cells are dependent upon androgen action and that AR up-regulation by 1,25-(OH)2D3 likely contributes to the synergistic actions of 1,25-(OH)2D3 and DHT in these cells.
Spatio-Temporal Expression Patterns of Steroidogenic Acute Regulatory Protein (StAR) During Follicular Development in the Rat Ovary*
Authors: Ronen-Fuhrmann Tamar , Timberg Rina , King Steven R. , Hales Karen H. , Hales Dale B. , Stocco Douglas M. , Orly Joseph 
Published: January 2014

AbstractThe steroidogenic acute regulatory protein (StAR) is a vital mitochondrial protein that is indispensable for the synthesis of steroid hormones in the steroidogenic cells of the adrenal cortex and the gonads. Recent studies have shown that StAR enhances the conversion of the substrate for all steroid hormones, cholesterol, into pregnenolone, probably by facilitating cholesterol entry into the inner compartment of the mitochondria where the steroidogenic cytochrome P450scc complex resides. To study the potential of StAR to affect ovarian steroidogenesis during follicular development, we examined the time-dependent expression of StAR protein and messenger RNA in PMSG/human CG (hCG)-treated immature rats. Western blot analyses and immunohistochemical and RT-PCR methodologies have revealed a biphasic expression of StAR in the ovaries responding to hormones. The first peak of StAR expression was generated by PMSG administration and lasted for 24 h. Furthermore, it was restricted to the entire network of the ovarian secondary interstitial tissue, as well as to a fewer scattered theca-interna cells. The second burst of StAR expression was observed in response to the LH surge, as simulated by hCG. This time, StAR was expressed in the entire theca-interna and interstitial tissue, as well as in those granulosa cells that were confined to periovulatory follicles. Immunoelectron microscopy studies revealed the over 90% of StAR antigenic sites are localized in the inner compartments of the mitochondrion, suggesting a rapid removal of StAR precursor from the mitochondrial surface, where it is believed to exert its activity. Altogether, our observations portray dynamic acute alterations of StAR expression during the process of follicular maturation in this animal model. Furthermore, if StAR indeed determines steroidogenic capacities in the ovary, our findings imply that, in immature rats undergoing hormonally induced first ovulation: 1) the early phases of follicular development are supported by androgen production originating from nonfollicular cells; 2) estrogen production in the granulosa cells of Graafian follicles is nourished by a submaximal androgenic output in the theca-interstitial compartments of the ovary.
Substitution of Ala564 in the First Zinc Cluster of the Deoxyribonucleic Acid (DNA)-Binding Domain of the Androgen Receptor by Asp, Asn, or Leu Exerts Differential Effects on DNA Binding*
Authors: Brüggenwirth Hennie T. , Boehmer Annemie L. M. , Lobaccaro Jean Marc , Chiche Laurent , Sultan Charles , Trapman Jan , Brinkmann Albert O. 
Published: January 2014

AbstractIn the androgen receptor of a patient with androgen insensitivity, the alanine residue at position 564 in the first zinc cluster of the DNA-binding domain was substituted by aspartic acid. In other members of the steroid receptor family, either valine or alanine is present at the corresponding position, suggesting the importance of a neutral amino acid residue at this site. The mutant receptor was transcriptionally inactive, which corresponded to the absence of specific DNA binding in gel retardation assays, and its inactivity in a promoter interference assay. Two other receptor mutants with a mutation at this same position were created to study the role of position 564 in the human androgen receptor on DNA binding in more detail. Introduction of asparagine at position 564 resulted in transcription activation of a mouse mammary tumor virus promoter, although at a lower level compared with the wild-type receptor. Transcription activation of an (ARE)2-TATA promoter was low, and binding to different hormone response elements could not be visualized. The receptor with a leucine residue at position 564 was as active as the wild-type receptor on a mouse mammary tumor virus promoter and an (ARE)2-TATA promoter, but interacted differentially with several hormone response elements in a gel retardation assay. The results of the transcription activation and DNA binding studies could partially be predicted from three-dimensional modeling data. The phenotype of the patient was explained by the negative charge, introduced at position 564.
Glucagon-Like Peptide-1-(7–36) Amide and Peptide YY Mediate Intraduodenal Fat-Induced Inhibition of Acid Secretion in Dogs*
Authors: Fung Leslie C. , Chisholm Connie , Greenberg Gordon R. 
Published: January 2014

AbstractIntraduodenal fat inhibits gastric acid secretion via the release of one or more hormonal enterogastrones thought to arise from ileo-colonic mucosa. This study determined whether glucagon-like peptide-1 (GLP-1)-(7–36) amide and peptide YY (PYY), colocalized in L cells found in the ileum, mediate intraduodenal fat-induced inhibition of stimulated gastric acid, and evaluated the influence of cholecystokinin-A (CCK-A) receptor activation. Gastric acid secretion in response to duodenal perfusions of 8% peptone was measured in conscious dogs with gastric and duodenal cannulas. Intraduodenal administration of a 10% fat emulsion suppressed gastric acid secretion by 72 ± 4% (P &lt; 0.001) and increased plasma levels of GLP-1 and PYY by 44 ± 5 and 46 ± 4 fmol/ml, respectively (both P &lt; 0.01). Pretreatment with the CCK-A receptor antagonist MK-329 completely reversed the inhibition of gastric acid by fat, suppressed rises of plasma GLP-1 (maximum change, 23 ± 4 fmol/ml), and reduced plasma PYY responses to baseline. Intravenous infusions of 50 pmol/kg·h GLP-1 or PYY, which reproduced plasma elevations after intraduodenal fat, inhibited gastric acid secretion by 66 ± 5% and 51 ± 6%, respectively (both P &lt; 0.01); coinfusions of GLP-1 and PYY abolished gastric acid secretion (P &lt; 0.001) without influencing plasma gastrin or somatostatin. Pretreatment with 1500 pmol/kg·h of the GLP-1 antagonist exendin-(9–39) amide did not alter the magnitude of inhibition of gastric acid caused by exogenous GLP-1. These results indicate that GLP-1 and PYY released by intraduodenal fat, in part through CCK-dependent pathways, are major enterogastrones in dogs. This inhibitory action occurs independent of circulating concentrations of somatostatin and gastrin and appears to involve a GLP-1 receptor distinct from that mediating incretin effects.