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OC Wallis
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YP Zhang
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M Wallis
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Pituitary growth hormone (GH), like several other protein hormones, shows an unusual episodic pattern of molecular evolution in which sustained bursts of rapid change are imposed on long periods of very slow evolution (near-stasis). A marked period of rapid change occurred in the evolution of GH in primates or a primate ancestor, and gave rise to the species specificity that is characteristic of human GH. We have defined more precisely the position of this burst by cloning and sequencing the GH genes for a prosimian, the slow loris (Nycticebus pygmaeus) and a New World monkey, marmoset (Callithrix jacchus). Slow loris GH is very similar in sequence to pig GH, demonstrating that the period of rapid change occurred during primate evolution, after the separation of lines leading to prosimians and higher primates. The putative marmoset GH is similar in sequence to human GH, demonstrating that the accelerated evolution occurred before divergence of New World monkeys and Old World monkeys/apes. The burst of change was confined largely to coding sequence for mature GH, and is not marked in other components of the gene sequence including signal peptide, 5' upstream region and introns. A number of factors support the idea that this episode of rapid change was due to positive adaptive selection. Thus (1) there is no apparent loss of function of GH in man compared with non-primates, (2) after the episode of rapid change the rate of evolution fell towards the slow basal level that is seen for most mammalian GHs, (3) the accelerated rate of substitution for the exons of the GH gene significantly exceeds that for introns, and (4) the amino acids contributing to the hydrophobic core of GH are strongly conserved when higher primate and other GH sequences are compared, and for coding sequences other than that coding for hydrophobic core residues the rate of substitution for non-synonymous sites (K(A)) is significantly greater than that for synonymous sites (K(S)). In slow loris, as in most non-primate mammals, there is no evidence for duplication of the GH gene, but in marmoset, as in rhesus monkey and man, the putative GH gene is one of a cluster of closely related genes.

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T Zhang Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA

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M S Roberson Department of Biomedical Sciences, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853, USA

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GnRH controls the synthesis and release of the pituitary gonadotropic hormones. MAP kinase (MAPK) cascades, including extracellular signal-regulated kinase (ERK) and c-Jun N-terminal kinase (JNK) pathways, are crucial for GnRH-induced gene activation. In the present study, we investigated the function of GnRH-induced MAPK phosphatases (MKPs) using an in vivo mouse model as well as the αT3–1 cell line. Following GnRH agonist stimulation, in vivo gene profiling demonstrated that both MKP-1 and MKP-2 are induced with distinct temporal profiles, suggesting differential roles of these MKPs in the regulation of MAPK activation. Elevated activity of MKP-2 in αT3–1 cells, through either overexpression or activation of the endogenous MKP-2 gene, was correlated with inhibition of GnRH-induced activation of ERK and JNK, as well as the expression of ERK- and JNK-dependent proto-oncogenes. These data supported the conclusion that GnRH-induced MKPs likely serve as negative feedback regulators that modulate MAPK activity and function in the GnRH signaling pathway.

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Jing He State Key Laboratory of Genetic Resource and Evolution, Department of Laboratory Medicine and Pathobiology and Banting and Best Diabetes Centre, The Graduate School, Laboratory for Conservation and Utilization of Bioresource, Kunming Institute of Zoology, Chinese Academy of Sciences, 32 Jiaochang Donglu, Kunming, Yunnan 650223, People's Republic of China

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David M Irwin State Key Laboratory of Genetic Resource and Evolution, Department of Laboratory Medicine and Pathobiology and Banting and Best Diabetes Centre, The Graduate School, Laboratory for Conservation and Utilization of Bioresource, Kunming Institute of Zoology, Chinese Academy of Sciences, 32 Jiaochang Donglu, Kunming, Yunnan 650223, People's Republic of China

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Rui Chen State Key Laboratory of Genetic Resource and Evolution, Department of Laboratory Medicine and Pathobiology and Banting and Best Diabetes Centre, The Graduate School, Laboratory for Conservation and Utilization of Bioresource, Kunming Institute of Zoology, Chinese Academy of Sciences, 32 Jiaochang Donglu, Kunming, Yunnan 650223, People's Republic of China
State Key Laboratory of Genetic Resource and Evolution, Department of Laboratory Medicine and Pathobiology and Banting and Best Diabetes Centre, The Graduate School, Laboratory for Conservation and Utilization of Bioresource, Kunming Institute of Zoology, Chinese Academy of Sciences, 32 Jiaochang Donglu, Kunming, Yunnan 650223, People's Republic of China

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Ya-Ping Zhang State Key Laboratory of Genetic Resource and Evolution, Department of Laboratory Medicine and Pathobiology and Banting and Best Diabetes Centre, The Graduate School, Laboratory for Conservation and Utilization of Bioresource, Kunming Institute of Zoology, Chinese Academy of Sciences, 32 Jiaochang Donglu, Kunming, Yunnan 650223, People's Republic of China
State Key Laboratory of Genetic Resource and Evolution, Department of Laboratory Medicine and Pathobiology and Banting and Best Diabetes Centre, The Graduate School, Laboratory for Conservation and Utilization of Bioresource, Kunming Institute of Zoology, Chinese Academy of Sciences, 32 Jiaochang Donglu, Kunming, Yunnan 650223, People's Republic of China

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Specific interactions among biomolecules drive virtually all cellular functions and underlie phenotypic complexity and diversity. Biomolecules are not isolated particles, but are elements of integrated interaction networks, and play their roles through specific interactions. Simultaneous emergence or loss of multiple interacting partners is unlikely. If one of the interacting partners is lost, then what are the evolutionary consequences for the retained partner? Taking advantages of the availability of the large number of mammalian genome sequences and knowledge of phylogenetic relationships of the species, we examined the evolutionary fate of the motilin (MLN) hormone gene, after the pseudogenization of its specific receptor, MLN receptor (MLNR), on the rodent lineage. We speculate that the MLNR gene became a pseudogene before the divergence of the squirrel and other rodents about 75 mya. The evolutionary consequences for the MLN gene were diverse. While an intact open reading frame for the MLN gene, which appears functional, was preserved in the kangaroo rat, the MLN gene became inactivated independently on the lineages leading to the guinea pig and the common ancestor of the mouse and rat. Gain and loss of specific interactions among biomolecules through the birth and death of genes for biomolecules point to a general evolutionary dynamic: gene birth and death are widespread phenomena in genome evolution, at the genetic level; thus, once mutations arise, a stepwise process of elaboration and optimization ensues, which gradually integrates and orders mutations into a coherent pattern.

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C M Klinge Department of Biochemistry and Molecular Biology, Center for Genetics and Molecular Medicine, University of Louisville School of Medicine, Louisville, Kentucky 40292, USA

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S C Jernigan Department of Biochemistry and Molecular Biology, Center for Genetics and Molecular Medicine, University of Louisville School of Medicine, Louisville, Kentucky 40292, USA

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K A Mattingly Department of Biochemistry and Molecular Biology, Center for Genetics and Molecular Medicine, University of Louisville School of Medicine, Louisville, Kentucky 40292, USA

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K E Risinger Department of Biochemistry and Molecular Biology, Center for Genetics and Molecular Medicine, University of Louisville School of Medicine, Louisville, Kentucky 40292, USA

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J Zhang Department of Biochemistry and Molecular Biology, Center for Genetics and Molecular Medicine, University of Louisville School of Medicine, Louisville, Kentucky 40292, USA

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One mechanism by which ligand-activated estrogen receptors α and β (ERα and ERβ) stimulate gene transcription is through direct ER interaction with specific DNA sequences, estrogen response elements (EREs). ERE-bound ER recruits coactivators that stimulate gene transcription. Binding of ER to natural and synthetic EREs with different nucleotide sequences alters ER binding affinity, conformation, and transcriptional activity, indicating that the ERE sequence is an allosteric effector of ER action. Here we tested the hypothesis that alterations in ER conformation induced by binding to different ERE sequences modulates ER interaction with coactivators and corepressors. CHO-K1 cells transfected with ERα or ERβ show ERE sequence-dependent differences in the functional interaction of ERα and ERβ with coactivators steroid receptor coativator 1 (SRC-1), SRC-2 (glucocorticoid receptor interacting protein 1 (GRIP1)), SRC-3 amplified in breast cancer 1 (AIB1) and ACTR, cyclic AMP binding protein (CBP), and steroid receptor RNA activator (SRA), corepressors nuclear receptor co-repressor (NCoR) and silencing mediator for retinoid and thyroid hormone recpetors (SMRT), and secondary coactivators coactivator associated arginine methyltransferase 1 (CARM1) and protein arginine methyltransferase 1 (PRMT1). We note both ligand-independent as well estradiol- and 4-hydroxytamoxifen-dependent differences in ER-coregulator activity. In vitro ER-ERE binding assays using receptor interaction domains of these coregulators failed to recapitulate the cell-based results, substantiating the importance of the full-length proteins in regulating ER activity. These data demonstrated that the ERE sequence impacts estradiol-and 4-hydroxytamoxifen-occupied ERα and ERβ interaction with coregulators as measured by transcriptional activity in mammalian cells.

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J Bian Department of Pediatrics, The Second Affiliated Hospital, Dalian Medical University, 467 Zhongshan Road, Shahekou District, Dalian 116027, China

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X M Bai Department of Pediatrics, The Second Affiliated Hospital, Dalian Medical University, 467 Zhongshan Road, Shahekou District, Dalian 116027, China

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Y L Zhao Department of Pediatrics, The Second Affiliated Hospital, Dalian Medical University, 467 Zhongshan Road, Shahekou District, Dalian 116027, China

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L Zhang Department of Pediatrics, The Second Affiliated Hospital, Dalian Medical University, 467 Zhongshan Road, Shahekou District, Dalian 116027, China

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Z J Liu Department of Pediatrics, The Second Affiliated Hospital, Dalian Medical University, 467 Zhongshan Road, Shahekou District, Dalian 116027, China

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Obesity is currently a worldwide pandemic. Leptin resistance is a main mechanism of obese human and rodents. The downregulation of the long form of the leptin receptor (Lrb) was involved in leptin resistance in diet-induced obese rats. In the studies, we investigated whether arcuate nucleus (ARC) silencing of Lrb would promote diet-induced obesity in rats. Lentiviral vectors expressing Lrb-shRNA were administered to 5-week-old male rats by ARC injection. Following viral delivery, the rats were provided with a high-fat diet (HFD) or a chow diet (CD). After 8 weeks of the diet, serum leptin, and insulin concentrations were measured by RIA, gene expression of Lrb in the ARC was detected by a real-time RT-PCR, and leptin signaling was examined by western blot. The Lrb-shRNA knocked down the expression of Lrb mRNA in infected regions by 54% for the HFD rats and 47% for the CD rats respectively. The Lrb knockdown reduced Stats3 activation and increased expression of Npy mRNA. The rats with reduced Lrb in the ARC showed a significant increase in energy intake and body weight (BW) again when fed with a HFD. By contrast, there were no effects of Lrb reduction on energy intake or BW when rats maintained on a low-fat chow. Our results provide evidence that Lrb knockdown selectively in the ARC promotes diet-induced obesity and associated metabolic complications in rats.

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W Lei
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T Hirose
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L-X Zhang
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H Adachi
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M J Spinella
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E Dmitrovsky
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A M Jetten
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ABSTRACT

We have cloned a cDNA encoding the full-length coding region of the human homologue of the germ cell nuclear factor (GCNF)/retinoid receptor-related testis-associated receptor (RTR), from a human testis cDNA library. The amino acid sequence of human GCNF/RTR is highly homologous to that of the mouse GCNF/RTR. The largest difference between the two homologues is a 15 amino acid deletion in the human GCNF/RTR at amino acid 47. The GCNF/RTR gene was localized on human chromosome 9. Northern blot analysis using poly(A)+ RNA from different human tissues showed that GCNF/RTR mRNA is most abundantly expressed in the testis. GCNF/RTR was also highly expressed in embryonic stem cells and embryonal carcinoma cells but repressed in its differentiated derivatives. Induction of differentiation of mouse embryonal carcinoma F9 cells and human embryonal carcinoma NTERA-2 clone Dl (NT2/D1) cells by all-trans retinoic acid was accompanied by a down-regulation of GCNF/RTR. Our observations suggest that GCNF/RTR plays a role in the control of gene expression in early embryogenesis and during spermatogenesis.

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E J Gold Department of Anatomy and Structural Biology and Centre for Gene Research, University of Otago, School of Medical Sciences, PO Box 913, Dunedin 9001, New Zealand.
Department of Physiology, University of Otago, School of Medical Sciences, PO Box 913, Dunedin 9001, New Zealand.
Monash Institute of Reproduction and Development, Monash University, Melbourne, Australia.
School of Biological and Molecular Sciences, Oxford Brookes University, Headington, Oxford, United Kingdom.

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X Zhang Department of Anatomy and Structural Biology and Centre for Gene Research, University of Otago, School of Medical Sciences, PO Box 913, Dunedin 9001, New Zealand.
Department of Physiology, University of Otago, School of Medical Sciences, PO Box 913, Dunedin 9001, New Zealand.
Monash Institute of Reproduction and Development, Monash University, Melbourne, Australia.
School of Biological and Molecular Sciences, Oxford Brookes University, Headington, Oxford, United Kingdom.

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A M Wheatley Department of Anatomy and Structural Biology and Centre for Gene Research, University of Otago, School of Medical Sciences, PO Box 913, Dunedin 9001, New Zealand.
Department of Physiology, University of Otago, School of Medical Sciences, PO Box 913, Dunedin 9001, New Zealand.
Monash Institute of Reproduction and Development, Monash University, Melbourne, Australia.
School of Biological and Molecular Sciences, Oxford Brookes University, Headington, Oxford, United Kingdom.

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S L Mellor Department of Anatomy and Structural Biology and Centre for Gene Research, University of Otago, School of Medical Sciences, PO Box 913, Dunedin 9001, New Zealand.
Department of Physiology, University of Otago, School of Medical Sciences, PO Box 913, Dunedin 9001, New Zealand.
Monash Institute of Reproduction and Development, Monash University, Melbourne, Australia.
School of Biological and Molecular Sciences, Oxford Brookes University, Headington, Oxford, United Kingdom.

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M Cranfield Department of Anatomy and Structural Biology and Centre for Gene Research, University of Otago, School of Medical Sciences, PO Box 913, Dunedin 9001, New Zealand.
Department of Physiology, University of Otago, School of Medical Sciences, PO Box 913, Dunedin 9001, New Zealand.
Monash Institute of Reproduction and Development, Monash University, Melbourne, Australia.
School of Biological and Molecular Sciences, Oxford Brookes University, Headington, Oxford, United Kingdom.

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G P Risbridger Department of Anatomy and Structural Biology and Centre for Gene Research, University of Otago, School of Medical Sciences, PO Box 913, Dunedin 9001, New Zealand.
Department of Physiology, University of Otago, School of Medical Sciences, PO Box 913, Dunedin 9001, New Zealand.
Monash Institute of Reproduction and Development, Monash University, Melbourne, Australia.
School of Biological and Molecular Sciences, Oxford Brookes University, Headington, Oxford, United Kingdom.

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N P Groome Department of Anatomy and Structural Biology and Centre for Gene Research, University of Otago, School of Medical Sciences, PO Box 913, Dunedin 9001, New Zealand.
Department of Physiology, University of Otago, School of Medical Sciences, PO Box 913, Dunedin 9001, New Zealand.
Monash Institute of Reproduction and Development, Monash University, Melbourne, Australia.
School of Biological and Molecular Sciences, Oxford Brookes University, Headington, Oxford, United Kingdom.

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J S Fleming Department of Anatomy and Structural Biology and Centre for Gene Research, University of Otago, School of Medical Sciences, PO Box 913, Dunedin 9001, New Zealand.
Department of Physiology, University of Otago, School of Medical Sciences, PO Box 913, Dunedin 9001, New Zealand.
Monash Institute of Reproduction and Development, Monash University, Melbourne, Australia.
School of Biological and Molecular Sciences, Oxford Brookes University, Headington, Oxford, United Kingdom.

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The mRNA expression of two activin growth factor subunits (βA- and βC-activin), activin receptor subunits (ActRIIA, ActRIIB) and the activin-binding protein follistatin, and peptide expression of βA-activin and βC-activin subunits, were examined in regenerating rat liver after partial hepatectomy (PHx). Liver samples were collected from adult, male Sprague–Dawley rats, 12–240 h (n=3–5 rats per time point) after PHx or from sham-operated controls at the same time points. Hepatocyte mitosis and apoptosis were assessed histologically and by in situ cell death detection. RT and PCR were used to assess relative gene expression. βA- and βC-activin peptide immunoreactivity was assessed in liver and serum samples by western blotting, whereas cellular expression was investigated by immunohistochemistry, using specific monoclonal antibodies. βA- and βC-activin mRNA dropped to < 50% of sham control values 12 h after PHx and remained at this level until 168 h post-PHx, when βA-activin expression increased to three times sham control values and βC-activin mRNA returned to pre-PHx levels. A peak in follistatin expression was observed 24–48 h post-PHx, coincident with an increase in hepatocyte mitosis. No changes were observed in ActRIIA mRNA, whereas ActRIIB expression paralleled that of βA-activin mRNA. βC-activin immunoreactive homo- and heterodimers were observed in regenerating liver and serum. Mitotic hepatocytes frequently contained βC-activin immunoreactivity, whereas apoptotic hepatocytes were often immunoreactive for βA-activin. We conclude that βA- and βC-activin subunit proteins are autocrine growth regulators in regenerating liver and when expressed independently lead to hepatocyte apoptosis or mitosis in a subset of hepatocytes.

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M Zhang Department of Animal Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100094, People’s Republic of China
State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, People’s Republic of China

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Y Tao Department of Animal Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100094, People’s Republic of China
State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, People’s Republic of China

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B Zhou Department of Animal Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100094, People’s Republic of China
State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, People’s Republic of China

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H Xie Department of Animal Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100094, People’s Republic of China
State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, People’s Republic of China

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F Wang Department of Animal Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100094, People’s Republic of China
State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, People’s Republic of China

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L Lei Department of Animal Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100094, People’s Republic of China
State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, People’s Republic of China

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L Huo Department of Animal Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100094, People’s Republic of China
State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, People’s Republic of China

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Q Sun Department of Animal Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100094, People’s Republic of China
State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, People’s Republic of China

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G Xia Department of Animal Physiology and Biochemistry, College of Biological Sciences, China Agricultural University, Beijing 100094, People’s Republic of China
State Key Laboratory of Reproductive Biology, Institute of Zoology, Chinese Academy of Sciences, Beijing 100080, People’s Republic of China

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Atrial natriuretic peptide (ANP) as well as its receptors is found in mammalian ovary and follicular cells and its function in oocyte meiotic maturation has also been reported in Xenopus, hamster and rat. But the results are controversial and the physiological mechanism of ANP on oocyte maturation is not clear, especially the relationship between gonadotrophin and ANP as well as the signal transduction, and these need further study. The present study conducted experiments to examine these questions by using drug treatment and Western blot analysis and focused on pig oocyte meiotic maturation and cumulus expansion in vitro. The results revealed that ANP could inhibited FSH-induced pig oocyte maturation and cumulus expansion and prevent the full phosphorylation of mitogen-activated protein kinase in both oocytes and cumulus cells, and that these inhibitory effects could be mimicked by 8-Br-cyclic guanosine 5′-monophosphate (8-Br-cGMP), but blocked by a protein kinase G (PKG) inhibitor KT5823. Zaprinast, a cGMP-specific phosphodiesterase inhibitor, could enhance the inhibitory effect of ANP on oocyte maturation. A specific analogue of ANP, C-ANP-(4–23), which binds to the natriuretic peptide receptor-C (NPRC), had no effect in either FSH-induced or spontaneous oocyte maturation. Treatment with forskolin, a stimulator of adenylate cyclase, had a biphasic effect; 44 h treatment induced cumulus expansion but inhibited oocyte maturation while 2 h treatment induced maturation of cumulus-enclosed oocytes (CEOs). Both ANP and C-ANP-(4–23) could inhibit the effect of forskolin on CEO maturation, and these inhibitory effects of ANP/C-ANP-(4–23) could be blocked by preincubation with pertussis toxin (PT), consistent with mediation by a Gi protein(s) in the cumulus cells. All these results suggest that ANP is a multifunctional regulator of FSH and forskolin on pig CEO maturation by two signalling mechanisms: one is via a cGMP/PKG pathway, the other is via NPRC receptors in cumulus cells and the activation of the PT-sensitive Gi protein(s).

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C A Bagnell
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Q Zhang
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K Ohleth
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M L Connor
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B R Downey
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B K Tsang
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L Ainsworth
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ABSTRACT

Northern analysis and in-situ hybridization were used to follow the development of relaxin gene expression in the newly forming corpus luteum (CL) after ovulation and throughout luteal development. Alkaline phosphatase (AP) was used as a marker of theca-derived lutein cells and the relationship between AP-positive and relaxin mRNA-containing cells was assessed. Ovaries from prepubertal pigs treated with pregnant mares serum gonadotrophin (PMSG)/human chorionic gonadotrophin (hCG) were collected during the periovulatory period and at various times during 19 days after ovulation. In addition, CL from cyclic pigs on days 10 and 16 were used to monitor relaxin gene expression in small and large luteal cells. Northern analysis revealed that relaxin gene expression increased with CL development in the PMSG/hCG-treated pig, reaching maximal levels at around day 14 post-ovulation. Thereafter, as the CL regressed, the level of relaxin mRNA declined. In CL from cyclic pigs at day 10 of the cycle, only small luteal cells expressed relaxin mRNA. However, by day 16 of the cycle, large luteal cells were the source of relaxin gene expression. In-situ hybridization studies revealed that in the early CL (up to 30 h post-ovulation), the relaxin gene transcript was observed in cells along the margins of the CL and in the core of the infolding follicle wall corresponding to the AP-positive, luteinized theca cell layer. As luteinization progressed, the theca and granulosa cell layers could no longer be distinguished morphologically (from 54 h after ovulation until day 9). However, the pattern of relaxin hybridization persisted along the periphery in bands of cells penetrating the CL, and coincided with areas of AP staining, indicating that the theca lutein cells were the site of relaxin gene expression. At day 14, relaxin hybridization and AP staining were distributed throughout the luteal tissue. With CL regression both AP staining and relaxin hybridization declined. This pattern of relaxin hybridization in the CL of the gonadotrophin-primed pig was identical to that observed in cyclic pigs on days 10 and 16 of the cycle. These findings indicate that theca interna cells retain their ability to express the relaxin gene following ovulation and luteinization. In the early CL, the small theca-derived lutein cells are the source of relaxin transcript. However, as the CL becomes fully differentiated, the large granulosa-derived lutein cells acquire the capacity to express the relaxin message.

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Kathryn L Auld
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Stephen P Berasi Pfizer Global Biotherapeutics Technologies, Pfizer BioTherapeutics Research and Development, Pfizer BioTherapeutics Research and Development, Pfizer BioTherapeutics Research and Development, Pfizer Oncology Research and Development, Former Wyeth Colleagues, Cambridge, Massachusetts, USA

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Yan Liu Pfizer Global Biotherapeutics Technologies, Pfizer BioTherapeutics Research and Development, Pfizer BioTherapeutics Research and Development, Pfizer BioTherapeutics Research and Development, Pfizer Oncology Research and Development, Former Wyeth Colleagues, Cambridge, Massachusetts, USA

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Michael Cain Pfizer Global Biotherapeutics Technologies, Pfizer BioTherapeutics Research and Development, Pfizer BioTherapeutics Research and Development, Pfizer BioTherapeutics Research and Development, Pfizer Oncology Research and Development, Former Wyeth Colleagues, Cambridge, Massachusetts, USA

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Ying Zhang Pfizer Global Biotherapeutics Technologies, Pfizer BioTherapeutics Research and Development, Pfizer BioTherapeutics Research and Development, Pfizer BioTherapeutics Research and Development, Pfizer Oncology Research and Development, Former Wyeth Colleagues, Cambridge, Massachusetts, USA

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Christine Huard Pfizer Global Biotherapeutics Technologies, Pfizer BioTherapeutics Research and Development, Pfizer BioTherapeutics Research and Development, Pfizer BioTherapeutics Research and Development, Pfizer Oncology Research and Development, Former Wyeth Colleagues, Cambridge, Massachusetts, USA

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Shoichi Fukayama Pfizer Global Biotherapeutics Technologies, Pfizer BioTherapeutics Research and Development, Pfizer BioTherapeutics Research and Development, Pfizer BioTherapeutics Research and Development, Pfizer Oncology Research and Development, Former Wyeth Colleagues, Cambridge, Massachusetts, USA

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Jing Zhang
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Sung Choe
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Wenyan Zhong Pfizer Global Biotherapeutics Technologies, Pfizer BioTherapeutics Research and Development, Pfizer BioTherapeutics Research and Development, Pfizer BioTherapeutics Research and Development, Pfizer Oncology Research and Development, Former Wyeth Colleagues, Cambridge, Massachusetts, USA

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Bheem M Bhat Pfizer Global Biotherapeutics Technologies, Pfizer BioTherapeutics Research and Development, Pfizer BioTherapeutics Research and Development, Pfizer BioTherapeutics Research and Development, Pfizer Oncology Research and Development, Former Wyeth Colleagues, Cambridge, Massachusetts, USA

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Ramesh A Bhat Pfizer Global Biotherapeutics Technologies, Pfizer BioTherapeutics Research and Development, Pfizer BioTherapeutics Research and Development, Pfizer BioTherapeutics Research and Development, Pfizer Oncology Research and Development, Former Wyeth Colleagues, Cambridge, Massachusetts, USA

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Eugene L Brown Pfizer Global Biotherapeutics Technologies, Pfizer BioTherapeutics Research and Development, Pfizer BioTherapeutics Research and Development, Pfizer BioTherapeutics Research and Development, Pfizer Oncology Research and Development, Former Wyeth Colleagues, Cambridge, Massachusetts, USA

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Robert V Martinez Pfizer Global Biotherapeutics Technologies, Pfizer BioTherapeutics Research and Development, Pfizer BioTherapeutics Research and Development, Pfizer BioTherapeutics Research and Development, Pfizer Oncology Research and Development, Former Wyeth Colleagues, Cambridge, Massachusetts, USA

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Based on its homology to the estrogen receptor and its roles in osteoblast and chondrocyte differentiation, the orphan nuclear receptor estrogen-related receptor α (ERRα (ESRRA)) is an intriguing therapeutic target for osteoporosis and other bone diseases. The objective of this study was to better characterize the molecular mechanisms by which ERRα modulates osteoblastogenesis. Experiments from multiple systems demonstrated that ERRα modulates Wnt signaling, a crucial pathway for proper regulation of bone development. This was validated using a Wnt-luciferase reporter, where ERRα showed co-activator-dependent (peroxisome proliferator-activated receptor gamma co-activator 1α, PGC-1α) stimulatory effects. Interestingly, knockdown of ERR α expression also enhanced WNT signaling. In combination, these data indicated that ERRα could serve to either activate or repress Wnt signaling depending on the presence or absence of its co-activator PGC-1α. The observed Wnt pathway modulation was cell intrinsic and did not alter β-catenin nuclear translocation but was dependent on DNA binding of ERRα. We also found that expression of active ERRα correlated with Wnt pathway effects on osteoblastic differentiation in two cell types, consistent with a role for ERRα in modulating the Wnt pathway. In conclusion, this work identifies ERRα, in conjunction with co-activators such as PGC-1α, as a new regulator of the Wnt-signaling pathway during osteoblast differentiation, through a cell-intrinsic mechanism not affecting β-catenin nuclear translocation.

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