bluuebunny/crossref_metadata_2025_split huggingface dataset:
Role of Gonadotropin-Releasing Hormone as an Autocrine Growth Factor in Human Ovarian Surface Epithelium1
Authors: Kang Sung Keun , Choi Kyung-Chul , Cheng Kwai Wa , Nathwani Parimal S. , Auersperg Nelly , Leung Peter C. K. 
Published: January 2014

AbstractEpithelial ovarian cancer, which accounts for 80–90% of all ovarian cancers, is the most common cause of death from gynecological malignancies and is believed to originate from the ovarian surface epithelium. In the present study we investigated the expression of GnRH and its receptor in human ovarian surface epithelial (hOSE) cells and provided novel evidence that GnRH may have antiproliferative effects in this tissue. Using RT-PCR and Southern blot analysis, we cloned the GnRH and GnRH receptor (GnRHR) in hOSE cells. Sequence analysis revealed that GnRH and its receptor have sequences identical to those found in the hypothalamus and pituitary, respectively. To address whether GnRH regulates its own and receptor messenger RNA (mRNA), the cells were treated with different concentrations of the GnRH agonist (d-Ala6)-GnRH. Expression levels of GnRH and its receptor were investigated using quantitative and competitive RT-PCR, respectively. Interestingly, a biphasic effect was observed for the GnRH and GnRHR mRNA levels. High concentrations of the GnRH agonist (10−7 and 10−9m) decreased GnRH and GnRHR mRNA levels, whereas a low concentration (10−11m) resulted in up-regulation of GnRH and receptor mRNA levels. Treatment with the GnRH antagonist, antide, prevented the biphasic effects of the GnRH agonist in hOSE cells, confirming the specificity of the response. Furthermore, to investigate the physiological significance, we studied receptor-mediated growth regulatory effects of GnRH in human ovarian surface epithelial cells. The cells were treated with GnRH analogs, and the proliferative index of cells was measured using a [3H]thymidine incorporation assay. (d-Ala6)-GnRH had a direct inhibitory effect on the growth of hOSE cells in a time- and dose-dependent manner. This antiproliferative effect of the GnRH agonist was receptor mediated, as cotreatment of hOSE cells with antide abolished the growth inhibitory effects of the GnRH agonist. The results strongly suggest that GnRH can act as an autocrine/paracrine regulator in hOSE cells.
Calcitriol-Induced Apoptosis in LNCaP Cells Is Blocked By
Overexpression of Bcl-21
Authors: Blutt Sarah E. , McDonnell Timothy J. , Polek Tara C. , Weigel Nancy L. 
Published: January 2014

Abstract
While the role of vitamin D in bone and mineral metabolism has been investigated extensively, the role of the vitamin D receptor in other tissues is less well understood. 1,25-dihydroxyvitamin D3 (calcitriol) can act as a differentiating agent in normal tissues and can inhibit the growth of many cancer cell lines including LNCaP prostate cancer cells. We have shown previously that calcitriol causes LNCaP cell accumulation in the G0/G1 phase of the cell cycle. In this study, we demonstrate that calcitriol also induces apoptosis of LNCaP cells. The calcitriol-induced apoptosis is accompanied by a down-regulation of Bcl-2 and Bcl-XL proteins, both of which protect cells from undergoing apoptosis. Other proteins important in apoptotic control, Bax, Mcl-1, and Bcl-Xs, are unaffected by calcitriol treatment. We find that overexpression of Bcl-2 blocks calcitriol-induced apoptosis and reduces, but does not eliminate, calcitriol-induced growth inhibition. We conclude that both regulation of cell cycle and the apoptotic pathway are involved in calcitriol action in prostate cancer cells.
Resveratrol Acts as a Mixed Agonist/Antagonist for Estrogen Receptors α and β*
Authors: Bowers Jennifer L. , Tyulmenkov Valentyn V. , Jernigan Sarah C. , Klinge Carolyn M. 
Published: January 2014

Abstract
Epidemiological evidence indicates that phytoestrogens inhibit cancer formation and growth, reduce cholesterol levels, and show benefits in treating osteoporosis. At least some of these activities are mediated through the interaction of phytoestrogens with estrogen receptors α and β (ERα and ERβ). Resveratrol, trans-3,5,4′-trihydroxystilbene, is a phytoestrogen in grapes that is present in red wine. Resveratrol was shown to bind ER in cytosolic extracts from MCF-7 and rat uteri. However, the contribution of ERα vs. ERβ in this binding is unknown. Here we report that resveratrol binds ERβ and ERα with comparable affinity, but with 7,000-fold lower affinity than estradiol (E2). Thus, resveratrol differs from other phytoestrogens that bind ERβ with higher affinity than ERα. Resveratrol acts as an estrogen agonist and stimulates ERE-driven reporter gene activity in CHO-K1 cells expressing either ERα or ERβ. The estrogen agonist activity of resveratrol depends on the ERE sequence and the type of ER. Resveratrol-liganded ERβ has higher transcriptional activity than E2-liganded ERβ at a single palindromic ERE. This indicates that those tissues that uniquely express ERβ or that express higher levels of ERβ than ERα may be more sensitive to resveratrol’s estrogen agonist activity. For the natural, imperfect EREs from the human c-fos, pS2, and progesterone receptor (PR) genes, resveratrol shows activity comparable to that induced by E2. We report that resveratrol exhibits E2 antagonist activity for ERα with select EREs. In contrast, resveratrol shows no E2 antagonist activity with ERβ. These data indicate that resveratrol differentially affects the transcriptional activity of ERα and ERβ in an ERE sequence-dependent manner.
Glucagon-Like Peptide-1 Induces Cell Proliferation and Pancreatic-Duodenum Homeobox-1 Expression and Increases Endocrine Cell Mass in the Pancreas of Old, Glucose-Intolerant Rats
Authors: Perfetti Riccardo , Zhou Jie , Doyle Máire E. , Egan Josephine M. 
Published: January 2014

AbstractGlucose homeostasis in mammals is maintained by insulin secretion from the β-cells of the islets of Langerhans. Type 2 diabetes results either from primary β-cell failure alone and/or a failure to secrete enough insulin to overcome insulin resistance. Here, we show that continuous infusion of glucagon-like peptide-1 (7–36) (GLP-1; an insulinotropic agent), to young and old animals, had effects on the β-cell of the pancreas other than simply on the insulin secretory apparatus. Our previous studies on a rodent model of glucose intolerance, the aging Wistar rat, show that a plateau in islet size, insulin content, and β-cell mass is reached at 13 months, despite a continuing increase in body weight. Continuous sc infusion of GLP-1 (1.5 pm/kg·min), over 5 days, resulted in normal glucose tolerance. Our current results in both young and old rats demonstrate that treatment caused an up-regulation of pancreatic-duodenum homeobox-1 (PDX-1) expression in islets and total pancreas, induced pancreatic cell proliferation, and β-cell neogenesis. The effects on levels of PDX-1 messenger RNA were abrogated by simultaneous infusion of Exendin (9–39), a specific antagonist of GLP-1. PDX-1 protein levels increased 4-fold in whole pancreata and 6-fold in islets in response to treatment.β -cell mass increased to 7.2 ± 0.58 from 4.88 ± 0.38 mg, treated vs. control, respectively, P&lt; 0.02. Total pancreatic insulin content also increased from 0.55± 0.02 to 1.32 ± 0.11 μg/mg total pancreatic protein. Therefore, GLP-1 would seem to be a unique therapy that can stimulate pancreatic cell proliferation and β-cell differentiation in the pancreas of rodents.
Female Fertility Is Reduced in Mice Lacking Ca2+/Calmodulin-Dependent Protein Kinase IV**This work was supported by an NIH Medical Scientist Training Program award (to J.Y.W.) and NIH Grants HD-07503 (to A.R.M.) and HD-1272 (to J.S.R.)
Authors: Wu Joy Y. , Gonzalez-Robayna Ignacio J. , Richards JoAnne S. , Means Anthony R. 
Published: January 2014

AbstractCa2+/calmodulin-dependent protein kinase IV (CaMKIV) is a serine/threonine protein kinase with limited tissue distribution. CaMKIV is highly expressed in the testis, where it is found in transcriptionally inactive elongating spermatids. We have recently generated mice deficient in CaMKIV. In the absence of CaMKIV, the exchange of sperm nuclear basic proteins in male spermatids is impaired, resulting in male infertility secondary to defective spermiogenesis. The involvement of CaMKIV in female fertility has not been addressed. Here we report that female fertility is markedly reduced in CaMKIV-deficient mice due to impaired follicular development and ovulation. CaMKIV is expressed in the ovary, where it is localized in granulosa cells. We further find that in cultured granulosa cells, CaMKIV expression and subcellular localization are hormonally regulated. As granulosa cells differentiate, CaMKIV levels decrease and the kinase translocates from the nucleus into the cytoplasm. Our results demonstrate a critical role for CaMKIV in female reproduction and point to a potential function in granulosa cell differentiation.
Vitamin D Is an Important Factor in Estrogen Biosynthesis of Both Female and Male Gonads*
Authors: Kinuta Keiko , Tanaka Hiroyuki , Moriwake Tadashi , Aya Kunihiko , Kato Shigeaki , Seino Yoshiki 
Published: January 2014

AbstractIn the present study, the role of vitamin D in the regulation of estrogen synthesis in gonads was investigated. Vitamin D receptor null mutant mice showed gonadal insufficiencies. Uterine hypoplasia and impaired folliculogenesis were observed in the female, and decreased sperm count and decreased motility with histological abnormality of the testis were observed in the male. The aromatase activities in these mice were low in the ovary, testis, and epididymis at 24%, 58%, and 35% of the wild-type values, respectively. The gene expression of aromatase was also reduced in these organs. Elevated serum levels of LH and FSH revealed hypergonadotropic hypogonadism in these mice. The gene expressions of estrogen receptor α and β were normal in gonads in these mice. Supplementation of estradiol normalized histological abnormality in the male gonads as well as in the female. Calcium supplementation increased aromatase activity and partially corrected the hypogonadism. When the serum calcium concentration was kept in the normal range by supplementation, the aromatase activity in the ovary increased to 60% of the wild-type level, but LH and FSH levels were still elevated. These results indicated that vitamin D is essential for full gonadal function in both sexes. The action of vitamin D on estrogen biosynthesis was partially explained by maintaining calcium homeostasis; however, direct regulation of the expression of the aromatase gene should not be neglected.
Knockout of the Murine Prostaglandin EP2 Receptor Impairs Osteoclastogenesis in Vitro*
Authors: Li Xiaodong , Okada Yosuke , Pilbeam Carol C. , Lorenzo Joseph A. , Kennedy Christopher R. J. , Breyer Richard M. , Raisz Lawrence G. 
Published: January 2014

Abstract
Prostaglandin E2 (PGE2) stimulates the formation of osteoclast-like tartrate-resistant acid phosphatase-positive multinucleated cells (TRAP + MNC) in vitro. This effect likely results from stimulation of adenylyl cyclase, which is mediated by two PGE2 receptors, designated EP2 and EP4. We used cells from mice in which the EP2 receptor had been disrupted to test its role in the formation of TRAP + MNC. EP2 heterozygous (±) mice in a C57BL/6 x 129/SvEv background were bred to produce homozygous null (EP2 −/−) and wild-type (EP2 +/+) mice. PGE2, PTH, or 1,25 dihydroxyvitamin D increased TRAP+ MNC in 7-day cultures of bone marrow cells from EP2 +/+ mice. In cultures from EP2 −/− animals, responses to PGE2, PTH, and 1,25 dihydroxyvitamin D were reduced by 86%, 58%, and 50%, respectively. A selective EP4 receptor antagonist (EP4RA) further inhibited TRAP+ MNC formation in both EP2 +/+ and EP2 −/− cultures. In cocultures of spleen and calvarial osteoblastic cells, the response to PGE2 or PTH was reduced by 92% or 85% when both osteoblastic cells and spleen cells were from EP2− /− mice, by 88% or 68% when only osteoblastic cells were from EP2 −/− mice and by 58% or 35% when only spleen cells were from EP2 −/− mice. PGE2 increased receptor activator of nuclear factor (NF)-kB ligand (RANKL) messenger RNA expression in osteoblastic and bone marrow cell cultures from EP2 +/+ mice 2-fold but had little effect on cells from EP2 −/− mice. Spleen cells cultured with RANKL and macrophage colony stimulating factor produced TRAP+ MNC. PGE2 increased the number of TRAP+ MNC in spleen cell cultures from EP2 +/+ mice but not in cultures from EP2 −/− mice. EP4RA had no effect on the PGE2 response in spleen cell cultures. PGE2 decreased the expression of messenger RNA for granulocyte-macrophage colony stimulating factor in spleen cell cultures from EP2+ /+ mice but had little effect on cells from EP2 −/− mice. These data demonstrate that the prostaglandin EP2 receptor plays a role in the formation of osteoclast-like cells in vitro. A major defect in EP2 −/− mice appears to be in the capacity of osteoblastic cells to stimulate osteoclast formation. In addition, there appears to be a defect in the response of cells of the osteoclastic lineage to PGE2 in EP2 −/− mice.
4-Hydroxytamoxifen Trans-Represses Nuclear Factor-κB Activity in Human Osteoblastic U2-OS Cells through Estrogen Receptor (ER)α, and Not through ERβ*
Authors: Quaedackers Monique E. , Van Den Brink Christina E. , Wissink Sacha , Schreurs Richard H. M. M. , Gustafsson Jan-Åke , Van Der Saag Paul T. , Van Der Burg Bart 
Published: January 2014

AbstractEstrogens are important mediators of bone homeostasis, and postmenopausal estrogen replacement therapy is extensively used to prevent osteoporosis. The biological effects of estrogen are mediated by receptors belonging to the superfamily of steroid/thyroid nuclear receptors, estrogen receptor (ER)α and ERβ. ERα, not only trans-activates target genes in a hormone-specific fashion, but it can also neutralize other transcriptional activators, such as nuclear factor (NF)-κB, causing repression of their target genes. A major mechanism by which estrogens prevent osteoporosis seems to be repression of transcription of NF-κB target genes, such as the osteoclast-activating cytokines interleukin-6 and interleukin-1. To study the capacity of both ERs in repression of NF-κB signaling in bone cells, we first carried out transient transfections with ERα or ERβ of the human osteoblastic U2-OS cell line, in which endogenous NF-κB was stimulated by tumor necrosis factor α. Repression by ERα was already observed without 17β-estradiol, whereas addition of the ligand increased repression to 90%. ERβ, however, was able to repress NF-κB activity only in the presence of ligand. Because it is known that some antiestrogens can also display tissue-specific agonistic properties, 4-hydroxytamoxifen was tested for its capacity in repressing NF-κB activity and was found to be active (albeit less efficient than 17β-estradiol) and, interestingly, only with ERα. The pure antagonist ICI 164,384 was incapable of repressing through any ER subtypes. Deletion analysis and the use of receptor ERα/ERβ-chimeras showed that the A/B domain, containing activation function-1, is essential for this suppressive action. Next, we developed stable transfectants of the human osteoblastic U2-OS cell line containing ERα or ERβ in combination with an NF-κB luciferase reporter construct. In these cell lines, repression of NF-κB activity was only mediated through ERα and not through ERβ. These findings offer new insights into the specific role of both ER subtypes in bone homeostasis and could eventually help in developing more specific medical intervention strategies for osteoporosis.
Insulinotropic Hormone Glucagon-Like Peptide 1 (GLP-1) Activation of Insulin Gene Promoter Inhibited by p38 Mitogen-Activated Protein Kinase*
Authors: Kemp Daniel M. , Habener Joel F. 
Published: January 2014

AbstractThe insulin gene promoter contains many transcriptional response elements that predispose the gene to a wide range of regulatory signals. Glucagon-like peptide 1 (GLP-1) stimulates insulin gene transcription by intracellular second messenger cascades leading to direct transcription factor activation or to the up-regulation of insulin promoter specific transcription factors. In these studies, we have identified a novel regulatory signaling mechanism acting on the rat insulin 1 promoter (rINS1) in the INS-1 β-cell line. In the presence of stimulatory concentrations of GLP-1 (0.1–100 nm) on rINS1 activity, inhibition of p38 mitogen-activated protein kinase (p38 MAPK) using SB 203580 resulted in a marked increase in promoter activity (maximum 3-fold) over GLP-1 alone, as determined by rINS1 promoter-luciferase reporter gene expression. This effect was revealed to be mediated via the cAMP response element (CRE) of rINS1, because site directed mutagenesis of the CRE motif in rINS1 abolished the increased response to SB 203580. Furthermore, inhibition of p38 MAPK uncovered a similar, more pronounced, response in the expression of a generic CRE promoter driven reporter gene. Time course dose-response studies indicate that the p38 MAPK induced inhibitory response may involve expression of immediate early genes (IEGs); maximum repression of rINS1 activity occurred after 4 h of treatment, comparable with regulatory responses by IEGs. In conclusion, these results demonstrate a novel signaling mechanism whereby p38 MAPK represses rINS1 promoter activity in response to GLP-1, suggesting the involvement of a robust regulatory control by p38 MAPK in insulin gene expression. The relevance of this mechanism may be most apparent during periods of cellular stress in which p38 MAPK activity is stimulated. In this regard, reduced insulin expression levels caused by chronic hyperglycemia (glucotoxicity) and/or hyperlipidemia (lipotoxicity) may be a direct consequence of this mechanism.
Determination of Three Isoforms of the Receptor Activator of Nuclear Factor-κΒ Ligand and Their Differential Expression in Bone and Thymus*
Authors: Ikeda Tohru , Kasai Michiyuki , Utsuyama Masanori , Hirokawa Katsuiku 
Published: January 2014

AbstractThe receptor activator of nuclear factor (NF)-κB ligand [RANKL; also known as tumor necrosis factor-related activation-induced cytokine, osteoprotegerin ligand, and osteoclast differentiation factor] is known to bind with the receptor activator of NF-κB (RANK) and act not only as a key factor for osteoclastogenesis but also as a regulator of lymphocyte development. In this study, we found two additional isoforms of RANKL. RANKL 2 has a shorter intracellular domain than the original RANKL (RANKL 1), and RANKL 3 lacks a transmembrane domain and was thought to act as a soluble form. In the bone marrow stromal cell line ST2 and preosteoblastic cell line MC3T3-E1, all three RANKL isoforms were detected, but the expression of RANKL 2 was preferentially suppressed by treatment with 1α,25-dihydroxyvitamin D3 and dexamethasone. In young adult thymus, CD4−CD8− double-negative cells were positive for all three isoforms, CD4+CD8+ double-positive cells were positive for RANKL 1 and RANKL 3 but negative for RANKL 2, and CD4+CD8− and CD4−CD8+ single-positive cells were positive for all three isoforms. Immunofluorescence analyses of NIH3T3 cells transfected with each RANKL isoform indicated that the three RANKL isoforms were translated, and RANKL 2 protein predominantly stayed in the endoplasmic reticulum and Golgi networks. These results indicate that there are three kinds of RANKL-RANK pathways. The presence of multiple RANKL-RANK pathways suggests a more complicated RANKL-RANK system for osteoclastogenesis or T cell differentiation than previously thought.
Mutagenesis of Basic Amino Acids in the Carboxyl-Terminal Region of Insulin-Like Growth Factor Binding Protein-5 Affects Acid-Labile Subunit Binding
Authors: Firth Sue M. , Clemmons David R. , Baxter Robert C. 
Published: January 2014

Abstract
Like insulin-like growth factor binding protein-3 (IGFBP-3), IGFBP-5 was recently shown to form ternary complexes with insulin-like growth factor (IGF) and the acid-labile subunit (ALS). Previous studies using IGFBP-5/IGFBP-6 chimeric proteins have identified major and minor ALS binding sites in the carboxyl-terminal and central regions, respectively of IGFBP-5. We now report that ALS binds to IGFBP-3 (Ka = 1.1 ± 0.1 liters/nmol) and IGFBP-5 (Ka = 1.8 ± 0.5 liters/nmol) with similar binding affinities. Using site-specific mutants, we have identified residues K211/R214/K217/R218 within the carboxyl-terminal region of IGFBP-5 as being essential for ALS binding. Mutation of K134R136 or K138K139 in the central region of IGFBP-5 resulted in a small decrease in ALS binding.
Evidence That Relaxin Inhibits Apoptosis in the Cervix and the Vagina during the Second Half of Pregnancy in the Rat*
Authors: Zhao Shuangping , Fields P. A. , Sherwood O. D. 
Published: January 2014

Abstract
The growth of the cervix and vagina that occurs during the second half of rat pregnancy is accompanied by an increase in both epithelial and stromal cells. Neither the mechanism(s) that regulates this accumulation of cells nor its hormonal control is known. To test the hypothesis that the rate of apoptosis declines during the second half of pregnancy, cervices and vaginas were collected on days 5, 10, 15, 18, and 21 of pregnancy. Terminal deoxynucleotidyl transferase-mediated deoxyuridine 5′-triphosphate nick end-labeling was used to detect apoptotic cells. The rate of apoptosis declined (P &lt; 0.05) in epithelial and stromal cells in both the cervix and vagina during the second half of pregnancy, when blood levels of relaxin are increasing. To test the hypothesis that relaxin inhibits apoptosis, cervices and vaginas were collected 6, 12, 24, 48, and 72 h after the neutralization of endogenous relaxin, on days 19–21 of pregnancy, with a monoclonal antibody for rat relaxin. Both the terminal deoxynucleotidyl transferase-mediated deoxyuridine 5′-triphosphate nick end-labeling method and electron microscopy were used to detect apoptotic cells. Withdrawal of relaxin caused an increase in the rate of apoptosis in both the cervix and the vagina (P &lt; 0.05). It is concluded that the rate of apoptosis declines in the cervix and the vagina during the second half of rat pregnancy, and that relaxin likely contributes to this process.
Comparative Analysis of Pharmacologic and/or Genetic Disruption of Cyclooxygenase-1 and Cyclooxygenase-2 Function in Female Reproduction in Mice*
Authors: Reese Jeff , Zhao Xuemei , Ma Wen-Ge , Brown Naoko , Maziasz Timothy J. , Dey S. K. 
Published: January 2014

AbstractCyclooxygenase (COX)-derived prostaglandins are critical in female reproduction. Gene targeting studies show that ovulation, fertilization, implantation, and decidualization are defective in COX-2 deficient mice. We used genetic and pharmacologic approaches to perturb COX function and examine the differential and synergistic effects of inhibition of COX-1, COX-2, or of both isoforms on reproductive outcomes during early pregnancy in mice. The results demonstrate that simultaneous inhibition of COX-1 and COX-2 produces more severe effects on early pregnancy events than inhibition of either isoform alone. The effects of pharmacological inhibition of COX-2 on female reproductive functions were less severe than the null mutation of the COX-2 gene. A combined approach showed that COX-2 inhibition in COX-1−/− mice induced complete reproductive failure, suggesting a lack of alternative sources of prostaglandin synthesis. This investigation raises caution regarding the indiscriminate use of COX inhibitors and shows for the first time the distinct and overlapping pathways of the cyclooxygenase systems in female reproduction.