bluuebunny/crossref_metadata_2025_split huggingface dataset:
Analysis of Ovarian Gene Expression in Follicle-Stimulating Hormone β Knockout Mice*
Authors: Burns Kathleen H. , Yan Changning , Kumar T. Rajendra , Matzuk Martin M. 
Published: January 2014

Abstract
FSH is a heterodimeric glycoprotein hormone that is produced in the gonadotroph cells of the anterior pituitary. It acts on Sertoli cells of the testis and granulosa cells of the ovary. We previously demonstrated that FSHβ knockout female mice are infertile due to a block in folliculogenesis preceding antral stage development. To investigate aberrations of ovarian gene regulation in the absence of FSH, we analyzed the expression of several important marker genes using Northern blot and in situ hybridization techniques. Key findings are as follows: 1) Follicles of FSHβ knockout mice develop a well organized thecal layer, which is positive for P450 17α-hydroxylase and LH receptor messenger RNAs (mRNAs). This indicates that theca recruitment is completed autonomously with respect to FSH. 2) Granulosa cells in FSH-deficient mice demonstrate an increase in FSH receptor mRNA, and decreases in P450 aromatase, serum/glucocorticoid-induced kinase, and inhibin/activin subunit mRNAs. These data support studies that implicate FSH signaling cascades in the expression of these genes. 3) In contrast to the thecal layer, granulosa cell populations in FSHβ knockout mice do not accumulate LH receptor mRNA. This suggests that although the granulosa cells have a block in proliferation at the antral follicle stage in the absence of FSH, they do not initiate programs of terminal differentiation as seen in luteinizing cells of wild-type ovaries. 4) Ovaries of FSH-deficient mice demonstrate a modest decrease in cyclin D2 mRNA, without up-regulation of cell cycle inhibitor mRNAs associated with luteinization (i.e. p15, p27, and p21). Although components of the FSH null phenotype may be caused by partial cyclin D2 loss of function, these findings indicate that the mechanisms of granulosa cell cycle arrest in FSHβ knockout mice are distinct from those of cycle withdrawal at luteinization. Underscoring the usefulness of the FSH-deficient mouse model, this study clarifies aspects of gonadotropin-dependent folliculogenesis, thecal layer development, cycle control in granulosa cells, and luteinization.
Characterization of Signal Transduction Pathway in Neurotropic Action of Angiotensin II in Brain Neurons
Authors: Yang Hong , Wang Xiangyu , Raizada Mohan K. 
Published: January 2014

AbstractInteraction of angiotensin II with the neuronal angiotensin type 1 receptor stimulates the PI3K signaling pathway. Our objective in this study was to investigate the hypothesis that the PI3K cascade regulates the neurotropic actions of angiotensin II in rat brain neurons. We followed growth associated protein-43 expression and neurite extension as markers of neurotropic activity. Angiotensin II, through its interaction with the angiotensin type 1 receptor, increased growth associated protein-43 expression and neurite extension. These effects were abolished by pretreatment of neurons with wortmannin and rapamycin, but not by PD 98059. Antisense oligonucleotides specific for p70S6 kinase also inhibited angiotensin II-stimulated neurotropic activity. These data confirm the involvement of PI3K and p70S6 kinase in angiotensin II-mediated neurotropic action. Further support for this was provided by the observation that angiotensin II caused a time-dependent stimulation of p70S6 kinase by an angiotensin type 1 receptor-mediated process. We also found that the neurotropic actions of angiotensin II are mediated by plasminogen activator inhibitor-1. Evidence for this includes 1) angiotensin II-stimulated neuronal plasminogen activator inhibitor-1 gene expression, 2) potent neurotropic action of exogenous plasminogen activator inhibitor-1, and 3) inhibitory neurotropic effect of angiotensin II by antisense oligonucleotide-mediated depletion of plasminogen activator inhibitor-1. Finally, we found that the neurotropic action of plasminogen activator inhibitor-1 is not blocked by either angiotensin type 1 receptor antagonist or inhibitors of PI3K or p70S6 kinase, indicating that the plasminogen activator inhibitor-1 step is downstream from the p70S6 kinase. These observations demonstrate that angiotensin II is a neurotropic hormone that engages a distinct PI3K-p70S6 kinase-plasminogen activator inhibitor-1 signaling pathway for this action.
Knockout Mice Lacking Steroidogenic Factor 1 Are a Novel Genetic Model of Hypothalamic Obesity
Authors: Majdic Gregor , Young Morag , Gomez-Sanchez Elise , Anderson Paul , Szczepaniak Lidia S. , Dobbins Robert L. , McGarry J. Denis , Parker Keith L. 
Published: January 2014

AbstractKnockout (KO) mice lacking steroidogenic factor 1 (SF-1) exhibit a phenotype that includes adrenal and gonadal agenesis, impaired gonadotropin expression, and abnormalities of the ventromedial hypothalamic nucleus (VMH). Studies in rodents with lesions of the ventromedial hypothalamus have implicated the VMH in body weight regulation, suggesting that SF-1 KO mice may provide a genetic model of obesity. To prevent death, SF-1 KO mice were rescued with corticosteroid injections, followed by syngeneic adrenal transplants from wild-type (WT) littermates. Corticosterone and ACTH levels in WT and SF-1 KO mice were indistinguishable, documenting restoration of hypothalamic-pituitary-adrenal function. Although weights at earlier ages did not differ significantly from WT littermates, SF-1 KO mice were significantly heavier by 8 wk of age and eventually weighed almost twice as much as WT controls. Obesity in SF-1 KO mice predominantly resulted from decreased activity rather than increased food intake. Leptin was increased markedly, insulin was modestly elevated, and glucose was indistinguishable from WT mice. Although sex steroids in rodents affect weight, ovariectomy did not abolish the weight difference between WT and SF-1 KO mice. These SF-1 KO mice are a genetic model of late-onset obesity that may help elucidate the role of the VMH in weight regulation.
Molecular Regulation of the IGF-Binding Protein-4 Protease System in Human Fibroblasts: Identification of a Novel Inducible Inhibitor
Authors: Chen Bing-Kun , Overgaard Michael T. , Bale Laurie K. , Resch Zachary T. , Christiansen Michael , Oxvig Claus , Conover Cheryl A. 
Published: January 2014

AbstractThe IGF-binding protein-4 (IGFBP-4) protease system is an important regulator of local IGF bioavailability and cell growth. Recently, the IGF-dependent IGFBP-4 protease secreted by cultured human fibroblasts was identified as pregnancy-associated plasma protein A (PAPP-A). In pregnancy serum, PAPP-A circulates as a disulfide-bound complex with the precursor form of major basic protein (pro-MBP), and in this complex PAPP-A’s proteolytic activity is not evident. In this study we analyzed the IGFBP-4 protease system in normal human fibroblasts to determine regulation outside of pregnancy. Treatment with the phorbol ester tumor promoter, β-phorbol 12,13-didecanoate (β-PDD), resulted in time-dependent inhibition of the IGF-dependent IGFBP-4 protease activity in cell-conditioned medium, which was evident at 6 h and complete by 24 h. PAPP-A mRNA was constitutively expressed in control cells, and levels were decreased only after 24 h of β-PDD treatment. Secretion of PAPP-A protein into conditioned medium did not change with β-PDD treatment. On the other hand, pro-MBP mRNA was undetectable in control human fibroblasts, and treatment with β-PDD induced pro-MBP mRNA and protein expression within 6 h. β-PDD-induced pro-MBP mRNA expression and protease inhibition were blocked with an inhibitor of RNA synthesis, actinomycin D. Actinomycin D had no effect on PAPP-A mRNA levels in the absence or presence of β-PDD. Similarly, transformation of human fibroblasts with simian virus 40 large T antigen resulted in the synthesis of pro-MBP mRNA and protein and inhibition of IGFBP-4 protease activity. Coculture of fibroblasts with cells transfected with pro-MBP cDNA resulted in inhibition of IGFBP-4 proteolytic activity without having any effect on PAPP-A synthesis. In summary, phorbol ester tumor promoters and simian virus 40 transformation regulate IGFBP-4 proteolysis in human fibroblasts through induction of a novel inhibitor of PAPP-A, pro-MBP. These findings expand our understanding of the IGFBP-4 protease system and suggest an additional level of local cell growth control.
Transcriptional Activation of the Ovine Follicle-Stimulating Hormone-β Gene by Gonadotropin- Releasing Hormone Involves Multiple Signal Transduction Pathways
Authors: Vasilyev Vyacheslav V. , Pernasetti Flavia , Rosenberg Suzanne B. , Barsoum Mark J. , Austin Darrell A. , Webster Nicholas J. G. , Mellon Pamela L. 
Published: January 2014

AbstractGnRH regulates gonadotrope cells through GnRH receptor activation of the PKC-, MAPK-, and calcium-activated signaling cascades. Due to the paucity of homologous model systems expressing FSHβ, little is known about the specific mechanisms involved in transcriptional regulation of this gene by GnRH. Previous studies from our laboratory demonstrated that the gonadotrope-derived LβT2 cell line expresses FSHβ mRNA. In the present study we characterized the mechanisms involved in GnRH regulation of the FSHβ promoter using this cell model. Using transfection assays, we show that GnRH regulation of the ovine FSHβ promoter involves at least two elements, present between −4152/−2878 and −2550/−1089 bp, in association with one or several elements within the proximal region of the promoter. Surprisingly, the two activating protein-1 sites previously shown to be involved in the FSHβ response to GnRH in heterologous cells do not play a role in GnRH responsiveness in the gonadotrope cell model. Here we demonstrate that calcium influx itself is not sufficient to confer the response, but it is necessary for both 12-O-tetradecanoyl-phorbol-13-acetate (TPA) and GnRH induction of the FSHβ gene. Moreover, we show that GnRH regulation of FSHβ gene expression is mediated by PKC and establish the presence of multiple PKC isozymes in LβT2 cells. Interestingly, GnRH and TPA induce activity of the FSHβ promoter through different, although possibly overlapping, pools of PKC isoforms. This is further supported by the use of a MAPK inhibitor, which abolishes the induction of FSHβ by GnRH, but not by TPA. In conclusion, we have demonstrated that calcium, PKC, and MAPK signaling systems are all involved in the induction of FSHβ gene expression by GnRH in the LβT2 mouse gonadotrope cell model.
Adenosine-Regulated Cell Proliferation in Pituitary Folliculostellate and Endocrine Cells: Differential Roles for the A1 and A2B Adenosine Receptors
Authors: Rees D. A. , Lewis M. D. , Lewis B. M. , Smith P. J. , Scanlon M. F. , Ham J. 
Published: January 2014

AbstractA1 and A2 adenosine receptors have been identified in the pituitary gland, but the cell type(s) on which they are located and their effects on pituitary cell growth are not known. Therefore, we analyzed the expression of A1 and A2 receptors in primary rat anterior pituitary cells, two pituitary folliculostellate (TtT/GF and Tpit/F1) and two pituitary endocrine (GH3 and AtT20) cell lines, and compared their effects on cell proliferation. In anterior pituitary and folliculostellate cells, adenosine and adenosine receptor agonists (5′-N-ethylcarboxamidoadenosine, a universal agonist, and CGS 21680, an A2A receptor agonist) stimulated cAMP levels with a rank order of potency that indicates the presence of functional A2B receptors. This stimulation, however, was not observed in either GH3 or AtT20 cells, where adenosine and the A1 receptor agonist 2-chloro-N6-cyclopentyladenosine inhibited VIP/forskolin-stimulated cAMP production. Expression of A2B and A1 receptors in the folliculostellate cells and that of the A1 receptor in the endocrine cells were confirmed by RT-PCR, immunocytochemistry, and ligand binding. Adenosine and 5′-N-ethylcarboxamidoadenosine dose-dependently (10 nm to 10 μm) stimulated growth in the folliculostellate, but not in the endocrine, cells, whereas in the latter, 100 μm adenosine and 2-chloro-N6-cyclopentyladenosine inhibited cell proliferation by slowing cell cycle progression. These data highlight the differential expression of A1 and A2B adenosine receptors in pituitary cells and provide evidence for opposing effects of adenosine on pituitary folliculostellate and endocrine cell growth.
Estradiol-Sensitive Afferents Modulate Long-Term Episodic Firing Patterns of GnRH Neurons
Authors: Nunemaker Craig S. , DeFazio R. Anthony , Moenter Suzanne M. 
Published: January 2014

Abstract
GnRH neurons comprise the final common pathway of an estrogen-sensitive pattern generator controlling fertility. To determine estradiol effects on GnRH neuron firing patterns, adult transgenic mice were ovariectomized (OVX), and half were treated with estradiol (OVX+E). One week later targeted single-unit extracellular recordings were made from GnRH neurons identified by green fluorescent protein expression. Estradiol markedly affected GnRH neuron firing patterns, increasing the percentage and duration of time these cells were quiescent (≤1 action current/min). Estradiol increased the interval between episodes of increased firing rate determined by Cluster analysis of recordings more than 45 min (OVX+E 38.8 ± 7.2 min, OVX 16.7 ± 2.1 min, n = 6 each). Possible mechanisms of estradiol modulation were examined by simultaneously blocking ionotropic secretion of γ-aminobutyric acid and glutamatergic receptors. This treatment had no effect on cells from OVX mice (n = 10), indicating episodic firing of GnRH neurons is not driven by activation of these receptors. Receptor blockade eliminated estradiol effects on GnRH neurons in the midventral preoptic area (n = 7) but not elsewhere (n = 7). Individual GnRH neurons thus display episodic firing patterns at intervals previously reported for secretory pulses. Estradiol modulates episode frequency to exert feedback control; in a substantial subset of GnRH neurons, estradiol feedback is enforced via GABAergic and/or glutamatergic afferents.
Increased Hepatic Peroxisome Proliferator-Activated Receptor-γ Coactivator-1 Gene Expression in a Rat Model of Intrauterine Growth Retardation and Subsequent Insulin Resistance
Authors: Lane Robert H. , MacLennan Nicole K. , Hsu Jennifer L. , Janke Sara M. , Pham Tho D. 
Published: January 2014

Abstract
Uteroplacental insufficiency and subsequent intrauterine growth retardation (IUGR) increase the risk of type 2 diabetes in humans and rats. Unsuppressed endogenous hepatic glucose production is a common component of the insulin resistance associated with type 2 diabetes. Peroxisome proliferator-activated receptor-γ coactivator-1 (PGC-1) mediates hepatic glucose production by controlling mRNA levels of glucose-6-phosphatase (G-6-Pase), phosphoenolpyruvate carboxykinase (PEPCK), and fructose-1,6-bisphosphatase (FBPase). We therefore hypothesized that gene expression of PGC-1 would be increased in juvenile IUGR rat livers, and this increase would directly correlate with hepatic mRNA levels of PEPCK, G-6-Pase, and FBPase, but not glucokinase. We found that IUGR hepatic PGC-1 protein levels were increased to 230 ± 32% and 310 ± 47% of control values at d 0 and d 21 of life, respectively. Similarly, IUGR hepatic PGC-1 mRNA levels were significantly elevated at both ages. Concurrent with the increased PGC-1 gene expression, IUGR hepatic mRNA levels of G-6-Pase, PEPCK, and FBPase were also significantly increased, whereas glucokinase mRNA levels were significantly decreased. These data suggest that increased PGC-1 expression and subsequent hepatic glucose production contribute to the insulin resistance observed in the IUGR juvenile rat.
Administration of 5α-Androstane-3α,17β-Diol to Female Tammar Wallaby Pouch Young Causes Development of a Mature Prostate and Male Urethra
Authors: Leihy Michael W. , Shaw Geoffrey , Renfree Marilyn B. , Wilson Jean D. 
Published: January 2014

AbstractSecretion of 5α-androstane-3α,17β-diol (5α-adiol) by the testes of the tammar wallaby is responsible for initiation of prostatic development after d 20 in male pouch young. To ascertain the role of this hormone in the subsequent growth and differentiation of the prostate and in the development of the male phallus, 5α-adiol was administered to tammar female pouch young in two regimens. Administration of the hormone by mouth (8 μg/g body weight·wk) between d 70 and 150 of pouch life caused prostate development equivalent to that in d 150 males and promoted growth and differentiation of the penis, but not masculinization of the urethra. Treatment with a small dose of 5α-adiol enanthate (1 μg/g body weight·wk) from d 20–150 produced similar results. However, administration of larger doses of 5α-adiol enanthate (10 or 100 μg/g body weight·wk) from d 20–150 caused supraphysiological growth of the prostate, development of a male-type urethra, and penile growth. These results indicate that prostatic development and penile growth can be initiated over a wide time period, but that formation of a male urethra requires androgen action before d 70, when male penile differentiation begins. This further strengthens the hypothesis that 5α-adiol is the circulating androgen responsible in this species for virilization during development.
Leptin Is Inversely Related to Age at Menarche in Human Females*
Authors: Matkovic Velimir , Ilich Jasminka Z. , Skugor Mario , Badenhop Nancy E. , Goel Prem , Clairmont Albert , Klisovic Dino , Nahhas Ramzi W. , Landoll John D. 
Published: January 2014

AbstractOver the last century there has been a trend toward an earlier onset of menarche attributed to better nutrition and body fatness. With the discovery of the obesity gene and its product, leptin, we reexamined this hypothesis from a new perspective. As delayed menarche and leanness are considered risk factors for osteoporosis, we also evaluated the relation between leptin and bone mass. Body composition and serum leptin levels were measured, and the timing of menarche was recorded in 343 pubertal females over 4 yr. Body composition was measured by dual x-ray absorptiometry, and leptin by a new RIA. All participants were premenarcheal at baseline (aged 8.3–13.1 yr). Leptin was strongly associated with body fat (r = 0.81; P &lt; 0.0001) and change in body fat (r = 0.58; P &lt; 0.0001). The rise in serum leptin concentration up to the level of 12.2 ng/mL (95% confidence interval, 7.2–16.7) was associated with the decline in age at menarche. An increase of 1 ng/mL in serum leptin lowered the age at menarche by 1 month. A serum leptin level of 12.2 ng/mL corresponded to a relative percent body fat of 29.7%, a body mass index of 22.3, and body fat of 16.0 kg. A gain in body fat of 1 kg lowered the timing of menarche by 13 days. Leptin was positively related to bone area (r = 0.307; P &lt; 0.0001) and change in bone area (r = 0.274; P &lt; 0.0001).A critical blood leptin level is necessary to trigger reproductive ability in women, suggesting a threshold effect. Leptin is a mediator between adipose tissue and the gonads. Leptin may also mediate the effect of obesity on bone mass by influencing the periosteal envelope. This may have implications for the development of osteoporosis and osteoarthritis.
Expression of Functional Leptin Receptors in the Human Ovary1
Authors: Karlsson Cecilia , Lindell Kajsa , Svensson Eva , Bergh Christina , Lind Peter , Billig Håkan , Carlsson Lena M. S. , Carlsson Björn 
Published: January 2014

The size of body fat stores is known to influence fertility, indicating a link between adipose tissue and the reproductive system. Studies in mice have identified the adipocyte-derived hormone, leptin (Ob protein), as a possible mediator of this effect. The aim of this study was to investigate the possibility that leptin may have direct effects on the human ovary. To probe this hypothesis we first analyzed the expression of leptin receptors in the human ovary. Transcripts encoding both the long and short isoforms of the leptin receptor were present in human granulosa cells and thecal cells; however, the short isoforms were expressed at much higher levels. Immunoreactive leptin was present in follicular fluid at levels similar to those found in serum. ob gene expression, however, was undetectable in the ovary, as determined by reverse transcription-PCR, whereas it was easily detected in adipose tissue. To determine whether leptin could induce a biological response in ovarian cells, we examined the effect of leptin on estradiol production in cultured granulosa cells. Leptin (100 ng/mL) inhibited LH (0.1 ng/mL)-stimulated estradiol production. In contrast, leptin had no effect on estradiol production in the absence of LH.
In conclusion, this study has demonstrated that the leptin receptor is expressed in the human ovary, that leptin is present in follicular fluid, and that leptin can induce a biological response in ovarian cells. These results suggest that leptin may have a direct effect on the human ovary.
Human Estrogen Receptor β-Gene Structure, Chromosomal Localization, and Expression Pattern1
Authors: Enmark Eva , Pelto-Huikko Markku , Grandien Kaj , Lagercrantz Svetlana , Lagercrantz Jacob , Fried Gabriel , Nordenskjöld Magnus , Gustafsson Jan-Åke 
Published: January 2014

The estrogen receptor (ER) is a ligand-activated transcription factor that mediates the effects of the steroid hormone 17β-estradiol, in both males and females. Since the isolation and cloning of ER, the consensus has been that only one such receptor exists.The finding of a second subtype of ER (ERβ) has caused considerable excitement amongst endocrinologists. In this article, we present data regarding the genomic structure and chromosomal localization of the human ERβ gene, demonstrating that two independent ER genes do exist in the human. Furthermore, we present data regarding the tissue distribution of human ERβ, showing that this receptor is expressed in multiple tissues. For instance, ERβ is found in developing spermatids of the testis, a finding of potential relevance for the ongoing debate on the effects of environmental estrogens on sperm counts. In addition, we find ERβ in ovarian granulosa cells, indicating that estrogens also participate in the regulation of follicular growth in the human.