Growth Hormone Transcription Research Articles

Study of the POU1f1 gene polymorphisms were associated with chicken growth traitsof Ross 308 broilers

This experiment was conducted in the poultry field of the Department of Livestock at the College of Agriculture and Marshlands /University of Thi-Qar for 42 days from 13/11 to 24/12/2020. The experiment included raising 100 broiler chickens of Ross 308 strain. The aim of this study was to detect the polymorphism of the PIT-1 gene in exon 6 of ROSS 308 broilers and their relationship to production performance with some biochemical blood traits. The PIT-1 gene is a transcription factor specific to the anterior lobe of the pituitary gland, and is involved in pituitary cell differentiation and production by mediating transcription of Growth hormone (GH) and Prolactin (PRL) and thyroid hormone (TSH-β) stimulation which make it an important gene for its effect on the productive traits in broilers. DNA was extracted from 100 birds, and the polymerase chain reaction and the Sequencing technology of Nitrogen Bases were used and the detection of genetic mutations occurring in them, and the results showed the presence of a point mutation (C1669T) in three genetic polymorphisms, namely CC , CT, and TT. There were highly significant differences (P>0.01) in the distribution ratios of genotypes, where the CC genotype scored the highest (82%), followed by the CT genotype(12%), and then the TT genotype(6%), and that the allelic frequency of the C allele is superior to that of the T allele. where they were 0.88 and. 0.12, respectively, and it was found that there was a significant difference (P<0.05) for the genotypes of the mutation (C1669T) on carcass weight, Dressing ratio, week body weight, relative breast weight, as well as serum total protein concentration at 42 days of age.

Dietary Chlorella vulgaris modulates the performance, antioxidant capacity, innate immunity, and disease resistance capability of Nile tilapia fingerlings fed on plant-based diets

This study assessed the impacts of dietary Chlorella vulgaris (ChV) on the growth, digestive enzymes activity, antioxidant status, immune responses, expression of hepatic cytokines and growth-related genes, and disease resistance capability of Nile tilapia (Oreochromis niloticus) fingerlings fed on plant-based diets. For this purpose, six tested diets were formulated to include 0.0 (control), 2.5, 5, 10, 15, and 20 g ChV/kg diet and were offered to the fish in triplicated groups for 70 days. A dose-dependent increase was observed in feed intake, specific growth rate, and weight gain (%) in ChV-fed fish but feed conversion ratios and survival rates % were not significantly changed among different ChV groups. Significantly higher serum protease, amylase, and lipase enzyme levels were detected in ChV-fed fish than the control group, especially in treatments of 10 – 15 g/kg diet. Feeding the fish with 10–20 g ChV/kg diet markedly increased serum total proteins, total lipids, and globulin levels. Similarly, glutathione peroxidase, superoxide dismutase, and catalase activities as well as serum lysozyme and respiratory burst activities, and total IgM levels were also elevated. On the other hand, lowest malondialdehyde levels were recorded in fish groups fed diets with 10 – 20 g ChV/kg diet compared with the control group. Bactericidal activities against Aeromonas hydrophila, Pseudomonas fluorescens, and Vibrio anguillarum were significantly higher as levels of dietary ChV increased up to 15 and 20 g/kg diet. Dietary ChV also upregulated the transcription of hepatic growth hormone, insulin-like growth factor 1, interleukin-1 beta, and tumor necrosis factor-alpha genes, particularly at 15 – 20 g/kg diet. However, feeding Nile tilapia fingerlings with 15 g ChV/kg diet is adequate to promote the performance and support antioxidant capacity, immune response, and resistance capability to bacterial infections.

Role of KCNAB2 expression in modulating hormone secretion in somatotroph pituitary adenoma.

Prior profiling of the human pituitary adenoma (PA) DNA methylome showed the potassium channel subunit-encoding gene KCNAB2 to be highly differentially methylated between nonfunctional PAs (NFPAs) and growth hormone (GH)-secreting PAs, with greater KCNAB2 methylation detected in secretory PAs. KCNAB2 encodes an aldo-keto reductase that, among other things, negatively regulates members of the voltage-gated potassium channel (Kv) family. In this study, the authors aimed to determine whether modulation of Kcnab2 expression would alter GH secretion in the GH3 mammosomatotroph rat cell line. In addition, they examined whether dosing GH3 cells with the antiarrhythmic drug quinidine, a known inhibitor of Kv and voltage-gated sodium channels, would affect hormonal secretion. Previously generated RNA-seq data were reanalyzed to compare KCNAB2 expression levels in human NFPAs and GH-secreting PAs. Kcnab2 was overexpressed in GH3 cells using plasmid transfection and knocked down using shRNA, with confirmation by quantitative polymerase chain reaction (qPCR). GH concentrations in cell culture supernatants collected 24 hours after cell seeding were measured using enzyme-linked immunosorbent assay (ELISA). Separately, quinidine was administered to GH3 cells at graduated doses. GH and prolactin concentrations in supernatants collected 48 hours after quinidine treatment were measured by fluorometric immunoassay. Modulation of expression at the transcript level in GH3 cells resulted in proportionate changes in the expression of GH mRNA and secretion of GH peptide, as confirmed by qPCR and ELISA. Specifically, partial knockdown of Kcnab2 was associated with fewer GH RNA transcripts and less GH secretion compared with controls, while augmentation of Kcnab2 expression was associated with more GH transcripts and secretion than the controls. Administration of quinidine (≥ 50 µM) reduced both GH and prolactin secretion in a dose-dependent fashion (p ≤ 0.05). GH secretion in a somatotroph cell line is partially dependent on KCNAB2 gene expression and may be mitigated in vitro by quinidine. These results collectively suggest a potential new target and pharmacological candidate to be considered in the development of clinical therapeutics for acromegaly.

Trans-omics analyses revealed differences in hormonal and nutritional status between wild and cultured female Japanese eel (Anguilla japonica)

Long-term stock decline in the Japanese eel (Anguilla japonica) is a serious issue. To reduce natural resource utilization in Japan, artificial hormonal induction of maturation and fertilization in the Japanese eel has been intensively studied. Recent experiment on feminized (by feeding a commercial diet containing estradiol-17β for first half year) cultured female eels have shown ovulation problems, which is seldom observed in captured wild female eels. Therefore, the aim of this study is to try to investigate causes of ovulation problem frequently seen in cultured female eels by comparative trans-omics analyses. The omics data showed low growth hormone and luteinizing hormone transcription levels in the brain and low sex hormone–binding globulin transcription levels in the liver of the cultured female eels. In addition, it was found that high accumulation of glucose-6-phosphate and, maltose in the liver of the cultured female eel. It was also found that docosahexaenoic (DHA) acid, eicosapentaenoic acid (EPA) and arachidonic acid (ARA) ratios in cultured female eels were quite different from wild female eels. The data suggested that ovulation problem in cultured female eels was possibly resulted from prolonged intake of a high-carbohydrate diet and/or suboptimal DHA/EPA/ARA ratios in a diet.

OR24-1 Structure-Function Analysis of Human OTX2 Variants Defines Required Region of C-Terminus for Pituitary, Eye, and Craniofacial Development

OTX2 is a homeobox transcription factor important for eye, craniofacial and midline development. Whole gene deletions and heterozygous mutations in OTX2 cause variable anomalies with incomplete penetrance, and most cases present with craniofacial / ocular abnormalities, and hypopituitarism, including either isolated or combined pituitary hormone deficiency. Patients with variants of unknown significance in OTX2 pose a dilemma for medical diagnosis. OTX2 is highly conserved evolutionarily: variable craniofacial defects are observed in heterozygous Otx2 null mice and zebrafish with knockdown of otx2b together with other genes. Thus, mouse and zebrafish offer opportunities for functional analysis of human patient variants. A patient diagnosed with combined pituitary hormone deficiency, including deficiencies in GH, ACTH, FSH, and LH, with no obvious ocular or craniofacial abnormalities, had an intriguing, rare, likely deleterious OTX2H230L/+ variant in a predicted protein-protein interaction domain within the C-terminus. We tested the functional significance of the variant allele. No differences in the transactivation properties were observed in cell culture transfections. To assess function in a more physiological context, we generated an Otx2 allelic series in mice using CRISPR/Cas9. This included nested C-terminal deletions, frameshifts, the OTX2H230L/+ allele and other missense mutations. Surprisingly, all Otx2 variants after codon 220 were tolerated; no gross ocular, craniofacial, or pituitary growth insufficiency phenotypes were noted. In contrast, ocular phenotypes were 100% penetrant in Otx2L219Pfs*17/+ mice, including unilateral or bilateral anophthalmia or microphthalmia. Given the time and cost of generating mouse models of human disease, we explored the utility of zebrafish to assess patient variants in OTX2. Although zebrafish have two otx2 genes, previous studies showed that morpholino knockdown of otx2b caused craniofacial defects that mimic those of human patients if an unrelated gene in the pathway was also knocked down. We sought to characterize the phenotypic consequences of a complete loss of function variant in zebrafish because it could offer a cleaner, more robust system for assessment of human variants than the use of multiple, gene-specific morpholinos. Zebrafish homozygous for an essential splice site mutation, otx2bc.507-2A>C (otx2bhu3625) died at 11 days post fertilization. Preliminary data suggest mutants have reduced growth hormone transcripts at day 5, and assessment of zebrafish mutant vision and eye morphology is underway. The mouse studies suggest that the patient OTX2H230L/+ variant is likely tolerated, as are other variants and deletions C-terminal to position 220 of OTX2. Analysis of zebrafish genetic loss of function mutants suggest they offer an avenue for assessing the functional significance of human OTX2 variants.

Regulation of growth hormone biosynthesis by Cdk5 regulatory subunit associated protein 1-like 1 (CDKAL1) in pituitary adenomas.

CDK5 regulatory subunit associated protein 1-like 1 (CDKAL1) is a tRNA-modifying enzyme that catalyzes 2-methylthiolation (ms2) and has been implicated in the development of type 2 diabetes (T2D). CDKAL1-mediated ms2 is important for efficient protein translation and regulates insulin biosynthesis in pancreatic cells. Interestingly, an association between T2D and release of growth hormone (GH) has been reported in humans. However, it is unknown whether CDKAL1 is important for hormone production in the pituitary gland. The present study investigated the role of CDKAL1 in GH-producing pituitary adenomas (GHPAs). CDKAL1 activity was suppressed in GHPAs, as evidenced by a decrease in ms2, compared with non-functioning pituitary adenomas (NFPAs), which do not produce specific hormones. Downregulation of Cdkal1 using small interfering and short hairpin RNAs increased the biosynthesis and secretion of GH in rat GH3 cells. Depletion of Cdkal1 increased the cytosolic calcium level via downregulation of DnaJ heat shock protein family (Hsp40) member C10 (Dnajc10), which is an endoplasmic reticulum protein related to calcium homeostasis. This stimulated transcription of GH via upregulation of Pit-1. Moreover, CDKAL1 activity was highly sensitive to proteostatic stress and was upregulated by suppression of this stress. Taken together, these results suggest that dysregulation of CDKAL1 is involved in the pathogenesis of GHPAs, and that modulation of the proteostatic stress response might control CDKAL1 activity and facilitate treatment of GHPAs.

Molecular basis of growth hormone daily mRNA and protein synthesis in rats

AimsDaily and seasonal rhythms coordinate the endocrine and metabolic functions. The pituitary gland is the master regulator of several endocrine activities, and its function is classically regulated by endocrine signals from its target glands as well as from the hypothalamus. The growth hormone (GH) produced and secreted by the anterior pituitary presents a pulsatile secretion throughout the 24-hour cycle. However, the molecular mechanisms regulating the daily pattern of GH secretion are still unclear. Herein we investigated whether circadian GH mRNA and protein synthesis is modulated by acute adjustments in the stability and expression of GH mRNA. Main methodsGH mRNA and protein content were evaluated by real-time PCR and Western blotting, respectively, in pituitary gland of rats euthanized every 3 h during a 24-h period at the Zeitgeber times (ZT3 to ZT24). The GH mRNA poly(A) tail length was determined by RACE-PAT assay. Key findingsWe identified two main peaks of GH mRNA level in the pituitary gland of rats; one in the middle of the light-cycle and another in the middle of the dark-cycle. The latter was associated with an increase in pituitary GH protein content. Interestingly, an increment in the poly(A) tail length of the GH transcript was observed in association to reduced migration rate of the GH transcript and increased mRNA content in the dark-cycle period. SignificanceOur findings provide evidence that changes in the GH mRNA poly(A) length may underlie the circadian pattern of GH mRNA and protein levels in the pituitary gland of rats.

Activin/follistatin system in grass carp pituitary cells: - Regulation by local release of growth hormone and luteinizing hormone and its functional role in growth hormone synthesis and secretion.

Gonadotrophin regulation by activin/follistatin system is well-documented, but the corresponding effect on growth hormone (GH) has not been fully characterized and with little information available in lower vertebrates, especially in fish models. In grass carp, local interactions of GH and luteinizing hormone (LH) can induce GH release and gene expression at pituitary level via autocrine/paracrine mechanisms. To shed light on the role of activin/follistatin system in GH regulation by local actions of GH and LH, grass carp activin βA and βB were cloned, shown to be single-copy genes expressed in the pituitary, and confirmed to encode activin proteins capable of transactivating promoter with activin-responsive elements. In grass carp pituitary cells, activin A and B were effective in reducing GH secretion and GH cell content with concurrent drop in GH mRNA level whereas the opposite was true for follistatin, the activin-binding protein known to neutralize the effects of endogenous activin. Treatment with activin A and B not only could suppress basal but also inhibit GH mRNA expression induced by GH and human chorionic gonadotropin (hCG), a functional analogue of LH in fish model. Apparently, down-regulation of GH mRNA by activin was mediated by reducing GH transcript stability with concurrent inhibition on GH promoter activity via the SMAD pathway. In reciprocal experiments, GH treatment was found to up-regulate activin βA, activin βB and follistatin mRNA levels in carp pituitary cells but the opposite was noted by removing endogenous GH with GH antiserum. Interestingly, parallel treatment with hCG could also inhibit basal as well as GH-induced activin βA, activin βB and follistatin gene expression. These results, as a whole, indicate that the pituitary activin/follistatin system can serve as a regulatory target for local interactions of GH and LH and contribute to GH regulation by autocrine/paracrine mechanisms in the carp pituitary.

Targeting growth hormone receptor in human melanoma cells attenuates tumor progression and epithelial mesenchymal transition via suppression of multiple oncogenic pathways.

Recent reports have confirmed highest levels of growth hormone (GH) receptor (GHR) transcripts in melanoma, one of the most aggressive forms of human cancer. Yet the mechanism of GH action in melanoma remains mostly unknown. Here, using human malignant melanoma cells, we examined the effects of GH excess or siRNA mediated GHR knock-down (GHRKD) on tumor proliferation, migration and invasion. GH promoted melanoma progression while GHRKD attenuated the same. Western blot analysis revealed drastic modulation of multiple oncogenic signaling pathways (JAK2, STAT1, STAT3, STAT5, AKT, mTOR, SRC and ERK1/2) following addition of GH or GHRKD. Further, we show that GH excess upregulates expression of markers of epithelial mesenchymal transition in human melanoma, while the effects were reversed by GHRKD. Interestingly, we observed consistent expression of GH transcript in the melanoma cells as well as marked modulation of the IGF receptors and binding proteins (IGF1R, IGF2R, IR, IGFBP2, IGFBP3) and the oncogenic HGF-MET mRNA, in response to excess GH or GHRKD. Our study thus identifies the mechanistic model of GH-GHR action in human melanoma and validates it as an important pharmacological target of intervention.

Irisin inhibition of growth hormone secretion in cultured tilapia pituitary cells

Irisin, the product of fibronectin type III domain-containing protein 5 (FNDC5) gene, is well-documented to be a regulator of energy metabolism. At present, not much is known about its biological function in non-mammalian species. In this study, a full-length tilapia FDNC5 was cloned and its tissue expression pattern has been confirmed. Based on the sequence obtained, we produced and purified recombinant irisin which could induce uncoupling protein 1 (UCP1) gene expression in tilapia hepatocytes. Further, the rabbit polyclonal irisin antiserum was produced and its specificity was confirmed by antiserum preabsorption. In tilapia pituitary cells, irisin inhibited growth hormone (GH) gene expression and secretion and triggered rapid phosphorylation of Akt, Erk1/2, and p38 MAPK. Furthermore, irisin-inhibited GH mRNA expression could be prevented by inhibiting PI3K/Akt, MEK1/2, and p38 MAPK, respectively. Apparently, fish irisin can act directly at the pituitary level to inhibit GH transcript expression via multiple signaling pathways.

A Common Phenotype Polymorphism in Mammalian Brains Defined by Concomitant Production of Prolactin and Growth Hormone.

Pituitary Prolactin (PRL) and Growth Hormone (GH) are separately controlled and sub-serve different purposes. Surprisingly, we demonstrate that extra-pituitary expression in the adult mammalian central nervous system (CNS) is coordinated at mRNA and protein levels. However this was not a uniform effect within populations, such that wide inter-individual variation was superimposed on coordinate PRL/GH expression. Up to 44% of individuals in healthy cohorts of mice and rats showed protein levels above the norm and coordinated expression of PRL and GH transcripts above baseline occurred in the amygdala, frontal lobe and hippocampus of 10% of human subjects. High levels of PRL and GH present in post mortem tissue were often presaged by altered responses in fear conditioning and stress induced hyperthermia behavioral tests. Our data define a common phenotype polymorphism in healthy mammalian brains, and, given the pleiotropic effects known for circulating PRL and GH, further consequences of coordinated CNS over-expression may await discovery.

RNAseq analysis of fast skeletal muscle in restriction-fed transgenic coho salmon (Oncorhynchus kisutch): an experimental model uncoupling the growth hormone and nutritional signals regulating growth.

BackgroundCoho salmon (Oncorhynchus kisutch) transgenic for growth hormone (Gh) express Gh in multiple tissues which results in increased appetite and continuous high growth with satiation feeding. Restricting Gh-transgenics to the same lower ration (TR) as wild-type fish (WT) results in similar growth, but with the recruitment of fewer, larger diameter, muscle skeletal fibres to reach a given body size. In order to better understand the genetic mechanisms behind these different patterns of muscle growth and to investigate how the decoupling of Gh and nutritional signals affects gene regulation we used RNA-seq to compare the fast skeletal muscle transcriptome in TR and WT coho salmon.ResultsIllumina sequencing of individually barcoded libraries from 6 WT and 6 TR coho salmon yielded 704,550,985 paired end reads which were used to construct 323,115 contigs containing 19,093 unique genes of which >10,000 contained >90 % of the coding sequence. Transcripts coding for 31 genes required for myoblast fusion were identified with 22 significantly downregulated in TR relative to WT fish, including 10 (vaspa, cdh15, graf1, crk, crkl, dock1, trio, plekho1a, cdc42a and dock5) associated with signaling through the cell surface protein cadherin. Nineteen out of 44 (43 %) translation initiation factors and 14 of 47 (30 %) protein chaperones were upregulated in TR relative to WT fish.ConclusionsTR coho salmon showed increased growth hormone transcripts and gene expression associated with protein synthesis and folding than WT fish even though net rates of protein accretion were similar. The uncoupling of Gh and amino acid signals likely results in additional costs of transcription associated with protein turnover in TR fish. The predicted reduction in the ionic costs of homeostasis in TR fish associated with increased fibre size were shown to involve multiple pathways regulating myotube fusion, particularly cadherin signaling.Electronic supplementary materialThe online version of this article (doi:10.1186/s12864-015-1782-z) contains supplementary material, which is available to authorized users.

STAT3 upregulation in pituitary somatotroph adenomas induces growth hormone hypersecretion.

Pituitary somatotroph adenomas result in dysregulated growth hormone (GH) hypersecretion and acromegaly; however, regulatory mechanisms that promote GH hypersecretion remain elusive. Here, we provide evidence that STAT3 directly induces somatotroph tumor cell GH. Evaluation of pituitary tumors revealed that STAT3 expression was enhanced in human GH-secreting adenomas compared with that in nonsecreting pituitary tumors. Moreover, STAT3 and GH expression were concordant in a somatotroph adenoma tissue array. Promoter and expression analysis in a GH-secreting rat cell line (GH3) revealed that STAT3 specifically binds the Gh promoter and induces transcription. Stable expression of STAT3 in GH3 cells induced expression of endogenous GH, and expression of a constitutively active STAT3 further enhanced GH production. Conversely, expression of dominant-negative STAT3 abrogated GH expression. In primary human somatotroph adenoma-derived cell cultures, STAT3 suppression with the specific inhibitor S3I-201 attenuated GH transcription and reduced GH secretion in the majority of derivative cultures. In addition, S3I-201 attenuated somatotroph tumor growth and GH secretion in a rat xenograft model. GH induced STAT3 phosphorylation and nuclear translocation, indicating a positive feedback loop between STAT3 and GH in somatotroph tumor cells. Together, these results indicate that adenoma GH hypersecretion is the result of STAT3-dependent GH induction, which in turn promotes STAT3 expression, and suggest STAT3 as a potential therapeutic target for pituitary somatotroph adenomas.

β-Hydroxybutyric Sodium Salt Inhibition of Growth Hormone and Prolactin Secretion via the cAMP/PKA/CREB and AMPK Signaling Pathways in Dairy Cow Anterior Pituitary Cells

β-hydroxybutyric acid (BHBA) regulates the synthesis and secretion of growth hormone (GH) and prolactin (PRL), but its mechanism is unknown. In this study, we detected the effects of BHBA on the activities of G protein signaling pathways, AMPK-α activity, GH, and PRL gene transcription, and GH and PRL secretion in dairy cow anterior pituitary cells (DCAPCs). The results showed that BHBA decreased intracellular cAMP levels and a subsequent reduction in protein kinase A (PKA) activity. Inhibition of PKA activity reduced cAMP response element-binding protein (CREB) phosphorylation, thereby inhibiting GH and PRL transcription and secretion. The effects of BHBA were attenuated by a specific Gαi inhibitor, pertussis toxin (PTX). In addition, intracellular BHBA uptake mediated by monocarboxylate transporter 1 (MCT1) could trigger AMPK signaling and result in the decrease in GH and PRL mRNA translation in DCAPCs cultured under low-glucose and non-glucose condition when compared with the high-glucose group. This study identifies a biochemical mechanism for the regulatory action of BHBA on GH and PRL gene transcription, translation, and secretion in DCAPCs, which may be one of the factors that regulate pituitary function during the transition period in dairy cows.

The acute salinity changes activate the dual pathways of endocrine responses in the brain and pituitary of tilapia

To analyze and compare the stress and osmoregulatory hormones and receptors in pituitary during acute salinity changes, the expression patterns of corticotropin releasing hormone (crh) in hypothalamus, prolactin (prl) releasing peptide (pRrp) in telencephalon and diencephalon, glucocorticoid receptors 2 (gr2), and mineralocorticoid receptor (mr), crh-r, pro-opiomelanocorticotropin (pomc), pRrp, prl, dopamine 2 receptor (d2-r), growth hormone (gh), gh-receptor (gh-r) and insulin-like growth hormone (igf-1) transcripts in pituitary were characterized in euryhaline tilapia. The results indicate that the crh transcripts increased in the hypothalamus and rostral pars distalis of the pituitary after the transfer of fish to SW. Similarly, the pRrp transcripts were more abundant in SW acclimated tilapia forebrain and hypothalamus. The crh-r, gr2 and mr transcripts were more expressed in rostral pars distalis and pars intermedia of pituitary at SW than FW tilapia. The data indicate that the SW acclimation stimulates these transcripts in the specific regions of the brain and pituitary which may be related to the activation of the hypothalamic–pituitary–interrenal (HPI)-axis. The results of dual in situ hybridization reveal that the transcripts of crh-r, gr2 and mr with pomc are highly co-localized in corticotrophs of pituitary. Furthermore, we demonstrate high expression of pRrp in the brain and low expression of pRrp and prl transcripts in the pituitary of SW fish. No crh-r and corticosteroid receptors were co-localized with prl transcripts in the pituitary. The gh-r and igf-1 mRNA levels were significantly increased in SW acclimated tilapia pituitary whereas there was no difference in the gh mRNA levels. The data suggest that the locally produced pRrp and d2-r may control and regulate the expression of prl mRNA in pituitary. Therefore, the dual roles of pRrp are involved in the stress (via brain-pituitary) and osmoregulatory (via pituitary) pathways in tilapia exposed to acute salinity changes.

Effect of dietary energy and protein restriction followed by realimentation on pituitary mRNA expression of growth hormone and related genes in lambs

The objective of the current study was to evaluate the influence of dietary energy and protein restriction followed by realimentation on pituitary growth hormone (GH), growth hormone-releasing hormone receptor (GHRHR), GH secretagogue receptor (GHSR), somatostatin receptor 1 (SSTR1), somatostatin receptor 2 (SSTR2), insulin-like growth factor 1 receptor (IGF-1R), and IGF-2 mRNA expression in lambs. Forty 3-month-old native Mongolian wether lambs were selected, and randomly assigned to control group (CON), moderately energy-restricted group (MR1), moderately protein-restricted group (MR2), or severely energy- and protein-restricted group (SR). The feed restriction stage lasted for 60 days and then all groups were fed the same diet for 90 days (realimentation stage). Pituitaries were collected from four lambs in each group at the end of the two stages. Pituitary gene expression was determined by quantitative real-time reverse transcription PCR. At the end of the restriction stage, the body weight of lambs in all restricted groups was significantly lower than that in the CON group. Pituitary GH, GHRHR, GHSR and IGF-2 expression in lambs in the SR group was greater than that in the CON group (P<0.05), whereas the mRNA expression of SSTR1, SSTR2 and IGF-1R did not change (P≥0.05). At the end of the realimentation stage, the body weight of lambs in the MR1 and MR2 groups was not different from that of lambs in the CON group (P>0.05). However, the body weight of lambs in the SR group was still lower than that in the CON group (P<0.05). The pituitary GH expression of lambs in the SR group was still greater (P<0.05) than that of the CON group, whereas expression of the other genes had returned to control levels. No differences were found in pituitary GH and related gene expression in lambs in the MR1 and MR2 groups compared with those in the CON group throughout the entire experiment (P>0.05). Our results indicated that moderate dietary energy and protein restriction did not influence pituitary GH and related gene expression. Only severe energy and protein restriction caused a significant increase in pituitary GH transcription, which lasted throughout the realimentation stage.

Rapid induction of the Growth Hormone Gene Transcription by Glucocorticoids In Vitro: Possible Involvement of Membrane Glucocorticoid Receptors and Phosphatidylinositol 3‐Kinase Activation

The regulation of transcription of the growth hormone (GH) gene by glucocorticoids was studied in MtT/S cells, a cell line derived from an oestrogen-induced mammotrophic tumour in the rat, and in the primary culture of the anterior pituitary gland of adult mice. The levels of the GH heteronuclear RNA (GH hnRNA), which are mainly determined by the transcription rate, increased by 25-fold during 24 h in response to dexamethasone (DEX; 1 μM) in MtT/S cells that were cultured in the medium containing charcoal-stripped serum for 7 days. The stimulatory effect of DEX on the GH hnRNA levels was detectable as early as 30 min. This rapid effect of DEX did not require on-going protein synthesis, whereas it was considered that DEX requires the presence of unknown cellular proteins produced independently of DEX stimulation. By contrast, on-going protein synthesis was required for DEX action when incubated for 6 h, as has been observed in the previous studies. The specific inhibitor of glucocorticoid receptor, RU486, inhibited both rapid (30 min) and delayed (6 h) the effects of glucocorticoids on GH hnRNA levels. Membrane impermeable glucocorticoid, corticosterone-bovine serum albumin conjugate (CSBSA), was found to have effects similar to those of DEX and free corticosterone (CS), suggesting that glucocorticoids regulate GH gene transcription at least in part through the membrane bound receptors. From pharmacological studies, it was suggested that phosphatidylinositol 3-kinase (PI3K) activation is involved in the rapid effects but not in the delayed effects of glucocorticoids. This also suggests that the delayed effects of glucocorticoids depend on mechanisms other than the activation of PI3-kinase. Finally, both rapid and delayed effects of CS and CSBSA were observed not only in MtT/S cells, but also in the mouse pituitary cells in primary culture. Therefore, it is possible that the membrane initiated action of glucocorticoids is involved in the regulation of GH transcription in normal pituitary cells, as well as in pituitary tumour cells.

Short-Chain Fatty Acids Inhibit Growth Hormone and Prolactin Gene Transcription via cAMP/PKA/CREB Signaling Pathway in Dairy Cow Anterior Pituitary Cells

Short-chain fatty acids (SCFAs) play a key role in altering carbohydrate and lipid metabolism, influence endocrine pancreas activity, and as a precursor of ruminant milk fat. However, the effect and detailed mechanisms by which SCFAs mediate bovine growth hormone (GH) and prolactin (PRL) gene transcription remain unclear. In this study, we detected the effects of SCFAs (acetate, propionate, and butyrate) on the activity of the cAMP/PKA/CREB signaling pathway, GH, PRL, and Pit-1 gene transcription in dairy cow anterior pituitary cells (DCAPCs). The results showed that SCFAs decreased intracellular cAMP levels and a subsequent reduction in PKA activity. Inhibition of PKA activity decreased CREB phosphorylation, thereby inhibiting GH and PRL gene transcription. Furthermore, PTX blocked SCFAs- inhibited cAMP/PKA/CREB signaling pathway. These data showed that the inhibition of GH and PRL gene transcription induced by SCFAs is mediated by Gi activation and that propionate is more potent than acetate and butyrate in inhibiting GH and PRL gene transcription. In conclusion, this study identifies a biochemical mechanism for the regulation of SCFAs on bovine GH and PRL gene transcription in DCAPCs, which may serve as one of the factors that regulate pituitary function in accordance with dietary intake.

Developmental transcription of genes putatively associated with growth in two sturgeon species of different growth rate

In the present study, we surveyed developmental changes in the transcription of growth hormone (gh), insulin-like growth factor-I (igf-I), ghrelin (ghrl) and vascular endothelial growth factor (vegf) genes in the largest freshwater fish, European sturgeon (Beluga, Huso huso) and compared the same parameters to that of its phylogenically close moderate-sized species, Persian sturgeon (Acipenser persicus). The transcripts of gh, igf-I, ghrl and vegf were detected at all developmental time-points of Persian sturgeon and Beluga from embryos to juvenile fish. Changes in normalized gh, igf-I, ghrl and vegf transcription by using the geometric average of genes encoding ribosomal protein L6 (RPL6) and elongation factor (EF1A) over the time of development of Persian sturgeon and Beluga were statistically significant (P<0.05). Our results showed that the mRNA expression levels of both igf-I and ghrl were low during early larval development and then increased significantly to the late larval time-points when larvae started exogenous feeding. In both Beluga and Persian sturgeon, after a low mRNA expression during the embryonic stage, the transcript levels of vegf displayed an increasing trend during yolk-sac fry, consistent with organogenesis. The vegf level remained constantly high in the time of exogenous feeding. The highest detection of gh transcripts coincided with the end of the embryonic stage (hatching time) in Persian sturgeon and 3days-post-hatching (dph) in Beluga. In Persian sturgeon, the gh transcript started to decrease to the rest of the developmental time-points, whereas in Beluga gh transcript had a marked second increase from the time of exogenous feeding (20-dph). This Beluga specific increase in gh transcription may be associated with the marked growth rate and extraordinary size of this fish species.

OR09-6 Placental growth hormone (GHV) is the predominant growth hormone transcript in MCF7 breast cancer cells

OR09-6 Placental growth hormone (GHV) is the predominant growth hormone transcript in MCF7 breast cancer cells