scholarly journals Identification of the growth hormone receptor in an advanced teleost, the tilapia (Oreochromis mossambicus) with special reference to its distinct expression pattern in the ovary

2004 ◽  
Vol 181 (1) ◽  
pp. 65-76 ◽  
Author(s):  
S Kajimura ◽  
N Kawaguchi ◽  
T Kaneko ◽  
I Kawazoe ◽  
T Hirano ◽  
...  
Keyword(s):  
Gene Expression ◽  
Growth Hormone Receptor ◽  
Oreochromis Mossambicus ◽  
Mrna Levels ◽  
Female Reproduction ◽  
Immature Oocytes ◽  
Putative Signal Peptide ◽  
Isolation And Characterization ◽  
Extracellular Region ◽  
Igf I

There is considerable evidence that the GH/IGF-I axis plays an important role in female reproduction. We report the isolation and characterization of the GH receptor (GH-R) and its gene expression profile during oogenesis in the tilapia, Oreochromis mossambicus. cDNA encoding GH-R was cloned and sequenced from the tilapia liver. The predicted GH-R preprotein consisted of 635 amino acids and contained a putative signal peptide, an extracellular region with a characteristic motif, a single transmembrane region, and a cytoplasmic region with conserved box 1 and 2 domains. The tilapia GH-R shared 34-74% identities with known GH-Rs in vertebrates. A binding assay using COS-7 cells showed that the cloned GH-R bound specifically to tilapia GH. Northern blot analysis showed a single mRNA transcript in the liver and ovary. In situ hybridization revealed intense signals of GH-R in the cytoplasm and nucleus of immature oocytes. The granulosa and theca cells surrounding vitellogenic oocytes also contained the GH-R mRNA signals. About a tenfold greater level of GH-R mRNA was found in the immature oocytes versus the mature oocytes, along with high levels of IGF-I mRNA. There were no significant changes in mRNA levels of GH-R and IGF-I in the liver or in plasma IGF-I levels during oocyte development. No correlation was found between hepatic GH-R mRNA and ovarian GH-R mRNA. These results suggest that the GH/IGF-I axis in the ovary may be involved in the early phases of oogenesis, under a different regulatory mechanism of GH-R gene expression from that of the liver.

scholarly journals Dexamethasone administration attenuates the inhibitory effect of lipopolysaccharide on IGF-I and IGF-binding protein-3 in adult rats

2005 ◽  
Vol 185 (3) ◽  
pp. 467-476 ◽  
Author(s):  
Teresa Priego ◽  
Miriam Granado ◽  
Ana Isabel Martín ◽  
Asunción López-Calderón ◽  
María Angeles Villanúa
Keyword(s):  
Gene Expression ◽  
Inhibitory Effect ◽  
Mrna Levels ◽  
Serum Concentrations ◽  
Gh Receptor ◽  
Its Gene ◽  
Igf I ◽  
Igf Binding ◽  
Igf Binding Protein ◽  
Igfbp 3

The aim of this study was to investigate whether glucocorticoid administration had a beneficial effect on serum concentrations of insulin-like growth factor I (IGF-I) and on IGF-binding protein 3 (IGFBP-3) in rats injected with lipopolysaccharide (LPS). Adult male rats were injected with LPS or saline and pretreated with dexamethasone or saline. Dexamethasone administration decreased growth hormone (GH) receptor and IGF-I mRNA levels in the liver of control rats. LPS decreased GH receptor and IGF-I gene expression in the liver of saline-treated rats but not in the liver of dexamethasone-pretreated rats. In the kidney, GH receptor mRNA levels were not modified by dexamethasone or LPS treatment. However, LPS decreased renal IGF-I gene expression and dexamethasone pretreatment prevented this decrease. Serum concentrations of IGF-I were decreased by LPS, and dexamethasone pretreatment attenuated this effect. The gene expression of IGFBP-3 in the liver and kidney and its circulating levels were decreased by LPS. In control rats dexamethasone increased circulating IGFBP-3 and its gene expression in the liver, and decreased the proteolysis of this protein. Dexamethasone pretreatment attenuated the LPS-induced decrease in IGFBP-3 gene expression in the liver and prevented the LPS-induced decrease in IGFBP-3 gene expression in the kidney. Moreover, dexamethasone pretreatment attenuated the LPS-induced decrease in serum concentrations of IGFBP-3 and decreased the LPS-induced IGFBP-3 proteolysis in serum. In conclusion, dexamethasone pretreatment partially attenuates the inhibitory effect of LPS on serum IGF-I by blocking the decrease of its gene expression in the kidney as well as by attenuating the decrease in serum concentrations of IGFBP-3.

scholarly journals Dairy cows experience selective reduction of the hepatic growth hormone receptor during the periparturient period

2004 ◽  
Vol 181 (2) ◽  
pp. 281-290 ◽  
Author(s):  
J Wook Kim ◽  
RP Rhoads ◽  
SS Block ◽  
TR Overton ◽  
SJ Frank ◽  
...  
Keyword(s):  
Gene Expression ◽  
Skeletal Muscle ◽  
Growth Hormone ◽  
Dairy Cows ◽  
Hormone Receptor ◽  
Growth Hormone Receptor ◽  
Late Pregnancy ◽  
Target Tissue ◽  
Ghr Gene ◽  
Igf I

At parturition, dairy cows experience a 70% reduction in plasma IGF-I. This reduction coincides with decreased abundance of GHR1A, the liver-specific transcript of the growth hormone receptor (GHR) gene, suggesting impaired growth hormone-dependent synthesis of IGF-I. It is not immediately obvious that the periparturient reduction in GHR1A is sufficient to reduce hepatic GHR abundance. This is because approximately 50% of total GHR mRNA abundance in prepartum liver is accounted for by ubiquitously expressed transcripts which remain collectively unchanged at parturition. In addition, the possibility that parturition alters GHR expression in other growth hormone target tissue has not been examined. To address these questions, we measured GHR gene expression and GHR protein in liver and skeletal muscle of four dairy cows on days -35,+3 and+56 (relative to parturition on day 0). Hepatic GHR abundance and GHR1A transcripts were lower on day+3 than on day -35 and returned to late pregnancy value by day+56. Additional studies in two other groups of cows indicated that the hepatic levels of the GHR protein recovered substantially within 10 days after parturition. These changes occurred without variation in the abundance of HNF4, a liver-enriched transcription factor activating the promoter responsible for GHR1A synthesis. In contrast to liver, levels of GHR gene expression and GHR protein were identical on days -35,+3 and+56 in skeletal muscle. These data suggest a role for the GHR in regulating tissue-specific changes in growth hormone responsiveness in periparturient dairy cows.

scholarly journals Prolactin 177, prolactin 188, and extracellular osmolality independently regulate the gene expression of ion transport effectors in gill of Mozambique tilapia

2015 ◽  
Vol 309 (10) ◽  
pp. R1251-R1263 ◽  
Author(s):  
Mayu Inokuchi ◽  
Jason P. Breves ◽  
Shunsuke Moriyama ◽  
Soichi Watanabe ◽  
Toyoji Kaneko ◽  
...  
Keyword(s):  
Gene Expression ◽  
Mrna Expression ◽  
Incubation Time ◽  
Oreochromis Mossambicus ◽  
Mrna Levels ◽  
Ion Transporters ◽  
Local Effects ◽  
Mozambique Tilapia ◽  
Gill Filaments ◽  
Euryhaline Teleost

This study characterized the local effects of extracellular osmolality and prolactin (PRL) on branchial ionoregulatory function of a euryhaline teleost, Mozambique tilapia ( Oreochromis mossambicus). First, gill filaments were dissected from freshwater (FW)-acclimated tilapia and incubated in four different osmolalities, 280, 330, 380, and 450 mosmol/kg H2O. The mRNA expression of Na+/K+-ATPase α1a (NKA α1a) and Na+/Cl− cotransporter (NCC) showed higher expression with decreasing media osmolalities, while Na+/K+/2Cl− cotransporter 1a (NKCC1a) and PRL receptor 2 (PRLR2) mRNA levels were upregulated by increases in media osmolality. We then incubated gill filaments in media containing ovine PRL (oPRL) and native tilapia PRLs (tPRL177 and tPRL188). oPRL and the two native tPRLs showed concentration-dependent effects on NCC, NKAα1a, and PRLR1 expression; Na+/H+ exchanger 3 (NHE3) expression was increased by 24 h of incubation with tPRLs. Immunohistochemical observation showed that oPRL and both tPRLs maintained a high density of NCC- and NKA-immunoreactive ionocytes in cultured filaments. Furthermore, we found that tPRL177 and tPRL188 differentially induce expression of these ion transporters, according to incubation time. Together, these results provide evidence that ionocytes of Mozambique tilapia may function as osmoreceptors, as well as directly respond to PRL to modulate branchial ionoregulatory functions.

scholarly journals Age-Related Alterations in Pituitary and Testicular Functions in Long-Lived Growth Hormone Receptor Gene-Disrupted Mice

Endocrinology ◽  
2007 ◽  
Vol 148 (12) ◽  
pp. 6019-6025 ◽  
Author(s):  
Varadaraj Chandrashekar ◽  
Christina R. Dawson ◽  
Eric R. Martin ◽  
Juliana S. Rocha ◽  
Andrzej Bartke ◽  
...  
Keyword(s):  
Growth Hormone Receptor ◽  
Receptor Gene ◽  
Delayed Puberty ◽  
Plasma Testosterone ◽  
Mrna Levels ◽  
Testosterone Levels ◽  
Gh Receptor ◽  
Age Related ◽  
Igf I ◽  
Plasma Prl

The somatotropic axis, GH, and IGF-I interact with the hypothalamic-pituitary-gonadal axis in health and disease. GH-resistant GH receptor-disrupted knockout (GHRKO) male mice are fertile but exhibit delayed puberty and decreases in plasma FSH levels, testicular content of LH, and prolactin (PRL) receptors, whereas PRL levels are elevated. Because the lifespan of GHRKO mice is much greater than the lifespan of their normal siblings, it was of interest to compare age-related changes in the hypothalamic-pituitary-gonadal axis in GHRKO and normal animals. Plasma IGF-I, insulin, PRL, LH, FSH, androstenedione and testosterone levels, and acute responses to GnRH and LH were measured in young (2–4 and 5–6 months of age) and old (18–19 and 23–26 months of age) male GHRKO mice and their normal siblings. Plasma IGF-I was not detectable in GHRKO mice. Plasma PRL levels increased with age in normal mice but declined in GHRKO males, and did not differ in old GHRKO and normal animals. Plasma LH responses to acute GnRH stimulation were attenuated in GHRKO mice but increased with age only in normal mice. Plasma FSH levels were decreased in GHRKO mice regardless of age. Plasma testosterone responses to LH stimulation were attenuated in old mice regardless of genotype, whereas plasma androstenedione responses were reduced with age only in GHRKO mice. Testicular IGF-I mRNA levels were normal in young and increased in old GHRKO mice, whereas testicular concentrations and total IGF-I levels were decreased in these animals. These findings indicate that GH resistance due to targeted disruption of the GH receptor gene in mice leads to suppression of testicular IGF-I levels, and modifies the effects of aging on plasma PRL levels and responses of the pituitary and testes to GnRH and LH stimulation. Plasma testosterone levels declined during aging in normal but not in GHRKO mice, and the age-related increase in the LH responses to exogenous GnRH was absent in GHRKO mice, perhaps reflecting a delay of aging in these remarkably long-lived animals.

Activation of insulin-like growth factor gene expression during work-induced skeletal muscle growth

1990 ◽  
Vol 259 (1) ◽  
pp. E89-E95 ◽  
Author(s):  
D. L. DeVol ◽  
P. Rotwein ◽  
J. L. Sadow ◽  
J. Novakofski ◽  
P. J. Bechtel
Keyword(s):  
Gene Expression ◽  
Skeletal Muscle ◽  
Growth Factor ◽  
Muscle Growth ◽  
Experimental Period ◽  
Mrna Levels ◽  
Insulin Like Growth Factor ◽  
Muscle Weight ◽  
Skeletal Muscle Growth ◽  
Igf I

We have investigated the hypothesis that there is local regulation of insulin-like growth factor (IGF) gene expression during skeletal muscle growth. Compensatory hypertrophy was induced in the soleus, a predominantly slow-twitch muscle, and plantaris, a fast-twitch muscle, in 11- to 12-wk-old female Wistar rats by unilateral cutting of the distal gastrocnemius tendon. Animals were killed 2, 4, or 8 days later, and muscles of the nonoperated leg served as controls. Muscle weight increased throughout the experimental period, reaching 127% (soleus) or 122% (plantaris) of control values by day 8. In both growing muscles, IGF-I mRNA, quantitated by a solution-hybridization nuclease-protection assay, rose by nearly threefold on day 2 and remained elevated throughout the experimental period. IGF-II mRNA levels also increased over controls. A more dramatic response was seen in hypophysectomized rats, where IGF-I mRNA levels rose by 8- to 13-fold, IGF-II values by 3- to 7-fold, and muscle mass increased on day 8 to 149% (soleus) or 133% (plantaris) of the control contralateral limb. These results indicate that signals propagated during muscle hypertrophy enhance the expression of both IGF genes, that modulation of IGF-I mRNA levels can occur in the absence of growth hormone, and that locally produced IGF-I and IGF-II may play a role in skeletal muscle growth.

scholarly journals Dose-response effects of a new growth hormone receptor antagonist (B2036-PEG) on circulating, hepatic and renal expression of the growth hormone/insulin-like growth factor system in adult mice

2000 ◽  
Vol 167 (2) ◽  
pp. 295-303 ◽  
Author(s):  
JW van Neck ◽  
NF Dits ◽  
V Cingel ◽  
IA Hoppenbrouwers ◽  
SL Drop ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Growth Factor ◽  
Receptor Antagonist ◽  
Growth Hormone Receptor ◽  
Binding Protein ◽  
Mrna Levels ◽  
Insulin Like Growth Factor ◽  
Gh Receptor ◽  
Igf I ◽  
Igfbp 3

The effects of growth hormone (GH) in regulating the expression of the hepatic and renal GH and insulin-like growth factor (IGF) system were studied by administering a novel GH receptor antagonist (GHRA) (B2036-PEG) at different doses (0, 1.25, 2.5, 5 and 10 mg/kg/day) to mice for 7 days. No differences were observed in the groups with respect to body weight, food consumption or blood glucose. However, a dose-dependent decrease was observed in circulating IGF-I levels and in hepatic and renal IGF-I levels at the highest doses. In contrast, in the 5 and 10 mg/kg/day GHRA groups, circulating and hepatic transcriptional IGF binding protein-3 (IGFBP-3) levels were not modified, likely resulting in a significantly decreased IGF-I/IGFBP-3 ratio. Hepatic GH receptor (GHR) and GH binding protein (GHBP) mRNA levels increased significantly in all GHRA dosage groups. Endogenous circulatory GH levels increased significantly in the 2.5 and 5 mg/kg/day GHRA groups. Remarkably, increased circulating IGFBP-4 and hepatic IGFBP-4 mRNA levels were observed in all GHRA administration groups. Renal GHR and GHBP mRNA levels were not modified by GHRA administration at the highest doses. Also, renal IGFBP-3 mRNA levels remained unchanged in most GHRA administration groups, whereas IGFBP-1, -4 and -5 mRNA levels were significantly increased in the 5 and 10 mg/kg/day GHRA administration groups. In conclusion, the effects of a specific GHR blockade on circulating, hepatic and renal GH/IGF axis reported here, may prove useful in the future clinical use of GHRAs.

Growth hormone induces tyrosine phosphorylation but does not alter insulin-like growth factor-I gene expression in human IM9 lymphocytes

1994 ◽  
Vol 13 (2) ◽  
pp. 127-136 ◽  
Author(s):  
P E Clayton ◽  
R N Day ◽  
C M Silva ◽  
P Hellmann ◽  
K H Day ◽  
...  
Keyword(s):  
Gene Expression ◽  
Tyrosine Phosphorylation ◽  
Northern Hybridization ◽  
Mrna Levels ◽  
Transduction Pathway ◽  
Exon 2 ◽  
Early Protein ◽  
Its Gene ◽  
Igf I ◽  
I Gene

ABSTRACT GH induces hepatic IGF-I synthesis by increasing transcription of its gene. IGF-I is synthesized, however, in many other tissues where the effect of GH on its gene expression is less well characterized. IGF-I and GH are produced by human lymphocytes and may function as autocrine regulators of lymphoproliferation. We have therefore used the human IM9 lymphocyte cell line to (A) define the IGF-I gene transcripts expressed and (B) investigate the effect of GH on early (protein tyrosine phosphorylation) and late (changes in IGF-I mRNA levels) events in intracellular signal transduction. Multiple IGF-I mRNA species, ranging in size from 0·9 to 5·8 kb, were detected by Northern hybridization of poly(A)+ mRNA from IM9 cells. The human IGF-I gene contains at least six exons and alternative splicing produces a number of transcripts. Solution hybridization with exon-specific riboprobes and amplification by PCR using exon-specific primers revealed that multiple transcripts were expressed in IM9 cells, and that exon 2 was the dominant leader exon. Treatment of IM9 cells with 200 ng recombinant human (rh)GH/ml led to the specific tyrosine phosphorylation of three intracellular proteins (93, 120 and 134 kDa), which are involved in the initial signalling of the GH transduction pathway. However a solution hybridization assay using the IGF-IA specific riboprobe on IM9 cell RNA from similar experiments revealed that GH treatment did not change IGF-I gene expression. This study has demonstrated (A) that the IGF-I gene is expressed in human IM9 lymphocytes, (B) that in contrast to other human tissue, exon 2 is the major leader exon, and (C) that rhGH induces tyrosine phosphorylation of 93, 120 and 134 kDa proteins but does not alter IGF-I gene expression. The IM9 cell may form an important model to investigate a GH transduction pathway not coupled to the IGF-I gene.

Altered skeletal pattern of gene expression in response to spaceflight and hindlimb elevation

1994 ◽  
Vol 267 (6) ◽  
pp. E822-E827 ◽  
Author(s):  
D. D. Bikle ◽  
J. Harris ◽  
B. P. Halloran ◽  
E. Morey-Holton
Keyword(s):  
Gene Expression ◽  
Alkaline Phosphatase ◽  
Bone Formation ◽  
Bone Mineralization ◽  
Mrna Levels ◽  
Skeletal Unloading ◽  
Compensatory Response ◽  
Factor I ◽  
Igf I ◽  
Skeletal Pattern

Spaceflight leads to osteopenia, in part by inhibiting bone formation. Using an animal model (hindlimb elevation) that simulates the weightlessness of spaceflight, we and others showed a reversible inhibition of bone formation and bone mineralization. In this study, we have measured the mRNA levels of insulin-like growth factor I (IGF-I), IGF-I receptor (IGF-IR), alkaline phosphatase, and osteocalcin in the tibiae of rats flown aboard National Aeronautics and Space Administration Shuttle Flight STS-54 and compared the results with those obtained from their ground-based controls and from the bones of hindlimb-elevated animals. Spaceflight and hindlimb elevation transiently increase the mRNA levels for IGF-I, IGF-IR, and alkaline phosphatase but decrease the mRNA levels for osteocalcin. The changes in osteocalcin and alkaline phosphatase mRNA levels are consistent with a shift toward decreased maturation, whereas the rise in IGF-I and IGF-IR mRNA levels may indicate a compensatory response to the fall in bone formation. We conclude that skeletal unloading during spaceflight or hindlimb elevation resets the pattern of gene expression in the osteoblast, giving it a less mature profile.

scholarly journals Insulin and IGF-I are necessary for FSH-induced cytochrome P450 aromatase but not cytochrome P450 side-chain cleavage gene expression in oestrogenic bovine granulosa cells in vitro

2002 ◽  
Vol 174 (3) ◽  
pp. 499-507 ◽  
Author(s):  
JM Silva ◽  
CA Price
Keyword(s):  
Gene Expression ◽  
Cytochrome P450 ◽  
Granulosa Cells ◽  
Side Chain ◽  
Mrna Levels ◽  
Side Chain Cleavage ◽  
P450 Aromatase ◽  
Chain Cleavage ◽  
Igf I

The earliest biochemical indicators of ovarian follicle deviation in cattle include lower oestradiol and free IGF concentrations in subordinate compared with dominant follicles. We determined if decreases in FSH, IGF-I or insulin cause decreased P450 aromatase (P450arom) or P450 cholesterol side-chain cleavage (P450scc) mRNA expression in oestrogenic bovine granulosa cells in vitro. In the first experiment, cells obtained from small follicles (2-5 mm diameter) were cultured in serum-free medium supplemented with physiological concentrations of FSH, IGF-I and insulin for 4 days. A decrease in specific hormone concentration was produced by replacing 70% of spent medium with medium devoid of FSH, insulin, or insulin and IGF-I on day 4 and again on day 5 of culture. Cultures were terminated on day 7. A reduction in FSH concentrations during the last 3 days of culture decreased P450arom and P450scc mRNA levels. A reduction in insulin reduced P450arom but not P450scc mRNA levels, and a reduction of both insulin and IGF-I concentrations further decreased P450arom mRNA levels and decreased P450scc mRNA levels. In a second experiment, cells obtained from small follicles (2-5 mm diameter) were cultured with insulin (100 ng/ml) without FSH for 4 days, and then insulin was withdrawn from the culture and FSH added for a further 3 days. The withdrawal of insulin decreased (P<0.02) oestradiol accumulation and reduced P450arom mRNA to below detectable levels, but did not affect P450scc mRNA levels. The addition of FSH transiently increased oestradiol secretion and P450arom mRNA levels, but P450arom mRNA levels were undetectable at the end of the culture period. The addition of FSH significantly enhanced P450scc mRNA levels and progesterone accumulation. These data demonstrated that a reduction of insulin-like activity reduced aromatase gene expression in bovine follicles without necessarily affecting progesterone synthetic capability, and thus may initiate follicle regression in cattle at the time of follicle divergence.

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