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Magda Vanderschueren-lodeweyckx - One of the best experts on this subject based on the ideXlab platform.
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Serum levels of Growth Hormone-Binding Protein and insulin-like Growth factor I in children and adolescents with type 1 (insulin-dependent) diabetes mellitus
Diabetologia, 1993Co-Authors: Guy Massa, L Dooms, Roger Bouillon, Magda Vanderschueren-lodeweyckxAbstract:Serum levels of insulin-like Growth factor I are reduced in patients with Type 1 (insulin-dependent) diabetes mellitus. To evaluate the role of the hepatic Growth hormone receptor in the decreased serum concentrations of insulin-like Growth factor I, serum levels of the high affinity Growth Hormone-Binding Protein, which is qualitatively and quantitatively related to the hepatic Growth hormone receptor, and of insulin-like Growth factor I were measured in 70 children and adolescents with Type 1 diabetes and 105 healthy control children. Analysis of variance revealed a significant negative effect of Type 1 diabetes on serum levels of the Growth Hormone-Binding Protein and of insulin-like Growth factor I. In the diabetic patients, serum levels of the Growth Hormone-Binding Protein were positively related to body mass index and to insulin dose per kg body weight, and were not influenced by pubertal stage, gender, or plasma levels of haemoglobin A1c. Serum levels of insulin-like Growth factor I increased during early puberty reaching peak levels at midpuberty and decreasing thereafter. No relationship was found between serum levels of Growth Hormone-Binding Protein and of insulin-like Growth factor I. Our data suggest that decreased liver somatogenic receptor levels, as reflected by the concentrations of circulating Growth Hormone-Binding Protein, play a minor role in the suppressed concentrations of circulating insulin-like Growth factor I. Post-Growth hormone receptor defects or changes in the insulin-like Growth factor binding Proteins probably contribute more to the lower serum levels of insulin-like Growth factor I.
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Comparison between the human serum Growth Hormone-Binding Protein and the water-soluble Growth Hormone-Binding site released from IM-9 lymphocytes.
Acta endocrinologica, 1993Co-Authors: Guy Massa, Mapoko Ilondo, Magda Vanderschueren-lodeweyckxAbstract:The characteristics of the human serum Growth Hormone-Binding Protein (GHBP) were compared with those of a water-soluble GH-binding site prepared by incubating cultured IM-9 lymphocytes in assay buffer with 25 mmol/l iodoacetamide. High-performance liquid chromatography gel filtration of the water-soluble GH-binding site incubated with 125I-labeled human GH ([125I]hGH) revealed a large peak of bound [125I]hGH eluting at the same position as the peak of [125I]hGH bound to the GHBP in serum. The estimated M(r) of the peak was 120,000, presumably representing one [125I]hGH bound to two binding sites. The binding specificities of the serum GHBP, the water-soluble GH-binding site and the GH receptor on IM-9 lymphocytes were identical. The binding affinities for 22,000 hGH and for 20,000 hGH of the serum GHBP were similar to the binding affinity of the water-soluble GH-binding site but lower than those of the cellular GH receptor. These findings show that the characteristics of the serum GHBP are comparable to those of the water-soluble GH-binding site released from IM-9 cells and support the hypothesis that in man the serum GHBP is produced by proteolytic cleavage of the cellular GH receptor.
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Serum levels of Growth Hormone-Binding Protein and insulin-like Growth factor-I during puberty.
Clinical endocrinology, 1992Co-Authors: Guy Massa, Roger Bouillon, Magda Vanderschueren-lodeweyckxAbstract:OBJECTIVE The aim was to investigate the effect of pubertal development on serum levels of Growth hormone binding Protein (GHBP) and IGF-I, and to study the relationship between GHBP levels and height standard deviation score (SDS), nutritional state and IGF-I levels. DESIGN AND PATIENTS The investigation was performed on serum samples from 72 healthy adolescents of different pubertal stage. Results were compared to those obtained in 46 prepubertal children. MEASUREMENTS Serum levels of GHBP were measured by HPLC gel filtration and IGF-I levels were measured by RIA after acid-ethanol extraction. RESULTS No effect of pubertal stage on serum levels of GHBP was found. A positive relationship was found between serum levels of GHBP and height SDS (r= 0.38; P < 0.005) and weight expressed as percentage of median weight for height age (r= 0.46; P < 0.0005). Serum levels of IGF-I increased during puberty and were not correlated with height SDS or weight for height age. In pubertal subjects, no relationship existed between serum levels of GHBP and IGF-I. In prepubertal subjects, however, a significantly positive relationship between GHBP and IGF-I levels (r= 0.66; P < 0.0005) was found. CONCLUSIONS Pubertal development does not seem to influence serum levels of GHBP. Height SDS and nutritional state are related to the concentration of GHBP. Before puberty, the level of GHBP is positively related to IGF-I levels; during puberty, however, the increase in serum IGF-I levels is not accompanied by changes in the amount of circulating GHBP.
Guy Massa - One of the best experts on this subject based on the ideXlab platform.
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Serum levels of Growth Hormone-Binding Protein and insulin-like Growth factor I in children and adolescents with type 1 (insulin-dependent) diabetes mellitus
Diabetologia, 1993Co-Authors: Guy Massa, L Dooms, Roger Bouillon, Magda Vanderschueren-lodeweyckxAbstract:Serum levels of insulin-like Growth factor I are reduced in patients with Type 1 (insulin-dependent) diabetes mellitus. To evaluate the role of the hepatic Growth hormone receptor in the decreased serum concentrations of insulin-like Growth factor I, serum levels of the high affinity Growth Hormone-Binding Protein, which is qualitatively and quantitatively related to the hepatic Growth hormone receptor, and of insulin-like Growth factor I were measured in 70 children and adolescents with Type 1 diabetes and 105 healthy control children. Analysis of variance revealed a significant negative effect of Type 1 diabetes on serum levels of the Growth Hormone-Binding Protein and of insulin-like Growth factor I. In the diabetic patients, serum levels of the Growth Hormone-Binding Protein were positively related to body mass index and to insulin dose per kg body weight, and were not influenced by pubertal stage, gender, or plasma levels of haemoglobin A1c. Serum levels of insulin-like Growth factor I increased during early puberty reaching peak levels at midpuberty and decreasing thereafter. No relationship was found between serum levels of Growth Hormone-Binding Protein and of insulin-like Growth factor I. Our data suggest that decreased liver somatogenic receptor levels, as reflected by the concentrations of circulating Growth Hormone-Binding Protein, play a minor role in the suppressed concentrations of circulating insulin-like Growth factor I. Post-Growth hormone receptor defects or changes in the insulin-like Growth factor binding Proteins probably contribute more to the lower serum levels of insulin-like Growth factor I.
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Comparison between the human serum Growth Hormone-Binding Protein and the water-soluble Growth Hormone-Binding site released from IM-9 lymphocytes.
Acta endocrinologica, 1993Co-Authors: Guy Massa, Mapoko Ilondo, Magda Vanderschueren-lodeweyckxAbstract:The characteristics of the human serum Growth Hormone-Binding Protein (GHBP) were compared with those of a water-soluble GH-binding site prepared by incubating cultured IM-9 lymphocytes in assay buffer with 25 mmol/l iodoacetamide. High-performance liquid chromatography gel filtration of the water-soluble GH-binding site incubated with 125I-labeled human GH ([125I]hGH) revealed a large peak of bound [125I]hGH eluting at the same position as the peak of [125I]hGH bound to the GHBP in serum. The estimated M(r) of the peak was 120,000, presumably representing one [125I]hGH bound to two binding sites. The binding specificities of the serum GHBP, the water-soluble GH-binding site and the GH receptor on IM-9 lymphocytes were identical. The binding affinities for 22,000 hGH and for 20,000 hGH of the serum GHBP were similar to the binding affinity of the water-soluble GH-binding site but lower than those of the cellular GH receptor. These findings show that the characteristics of the serum GHBP are comparable to those of the water-soluble GH-binding site released from IM-9 cells and support the hypothesis that in man the serum GHBP is produced by proteolytic cleavage of the cellular GH receptor.
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Serum levels of Growth Hormone-Binding Protein and insulin-like Growth factor-I during puberty.
Clinical endocrinology, 1992Co-Authors: Guy Massa, Roger Bouillon, Magda Vanderschueren-lodeweyckxAbstract:OBJECTIVE The aim was to investigate the effect of pubertal development on serum levels of Growth hormone binding Protein (GHBP) and IGF-I, and to study the relationship between GHBP levels and height standard deviation score (SDS), nutritional state and IGF-I levels. DESIGN AND PATIENTS The investigation was performed on serum samples from 72 healthy adolescents of different pubertal stage. Results were compared to those obtained in 46 prepubertal children. MEASUREMENTS Serum levels of GHBP were measured by HPLC gel filtration and IGF-I levels were measured by RIA after acid-ethanol extraction. RESULTS No effect of pubertal stage on serum levels of GHBP was found. A positive relationship was found between serum levels of GHBP and height SDS (r= 0.38; P < 0.005) and weight expressed as percentage of median weight for height age (r= 0.46; P < 0.0005). Serum levels of IGF-I increased during puberty and were not correlated with height SDS or weight for height age. In pubertal subjects, no relationship existed between serum levels of GHBP and IGF-I. In prepubertal subjects, however, a significantly positive relationship between GHBP and IGF-I levels (r= 0.66; P < 0.0005) was found. CONCLUSIONS Pubertal development does not seem to influence serum levels of GHBP. Height SDS and nutritional state are related to the concentration of GHBP. Before puberty, the level of GHBP is positively related to IGF-I levels; during puberty, however, the increase in serum IGF-I levels is not accompanied by changes in the amount of circulating GHBP.
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Ontogeny and nutritional regulation of the serum Growth Hormone-Binding Protein in the rat.
Acta endocrinologica, 1991Co-Authors: Nkuadi Mulumba, Guy Massa, Jean-marie Ketelslegers, Marc MaesAbstract:The ontogeny and the nutritional regulation of the serum Growth Hormone-Binding Protein in Wistar rats was studied in vitro using Ultrogel AcA34 filtration of serum incubated with 125I-bovine Growth hormone. The level of the specific binding of GH to serum GH-binding Protein was low in 1-week-old rats (female rats 2.3 +/- 0.9%; N = 6, and male rats 2.1 +/- 8%; N = 6) and increased with puberty, to reach 10-fold higher levels in 12-week-old adult female (26.1 +/- 2.3%; N = 6) and 5-fold higher levels in adult male rats (11.2 +/- 0.9%; N = 6). From 6 weeks of age and onwards, the level of serum GH-binding Protein was significantly higher in female than in male rats, reflecting sexual dimorphism. The nutritional dependence of GH-binding Protein was supported by the 46% decline of serum GH-binding Protein levels in 6-week-old female rats fasted for 3 days (11.6 +/- 0.9 and 6.3 +/- 1.1% in control and fasted rats, respectively; N = 8/group; p less than 0.001). After 4 days of refeeding, no difference was found between control and experimental animals. During development and after nutritional manipulation, Scatchard analysis revealed that the changes in GH-binding Protein were due to changes in binding capacity and not affinity. The levels of serum GH-binding Protein were positively correlated with the levels of hepatic GH binding sites, suggesting that the regulation of both Proteins is closely related during development and in states of nutritional sufficiency and deprivation.
L E Underwood - One of the best experts on this subject based on the ideXlab platform.
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Tissue-specific developmental regulation of the messenger ribonucleic acids encoding the Growth hormone receptor and the Growth hormone binding Protein in rat fetal and postnatal tissues.
Pediatric research, 1992Co-Authors: J L Walker, B M Moats-staats, A D Stiles, L E UnderwoodAbstract:Tissue responsiveness to Growth hormone is likely to be regulated by local concentrations and availability of the membrane-bound Growth hormone receptor (GHR) and perhaps by the actions of the soluble Growth hormone binding Protein (GHBP). To determine whether the developmental regulation of the GHR and GHBP might vary among tissues, we have measured the relative abundance of the 4.3-kb GHR and 1.3-kb GHBP mRNA in rat fetal and postnatal liver, kidney, lung, and ileum by Northern hybridization of polyadenylated RNA with a 32P-labeled antisense riboprobe prepared from a rat GHR cDNA. The GHR and GHBP mRNA were both present in the four tissues studied at fetal age 19 d (E19). In postnatal liver, both transcripts increased in abundance 3- to 4-fold after 14 d to mature levels at 42 d (p = 0.0001). Similar changes were seen in postnatal kidney for GHR mRNA abundance; however, GHBP mRNA abundance increased only 2- to 3-fold to mature levels by 28 d (kidney GHR versus GHBP mRNA profile, p = 0.0001). In lung, a 2-fold linear increase in GHR mRNA abundance was observed (p = 0.0019), but the GHBP mRNA did not change (GHR versus GHBP mRNA profile, p = 0.0006). Both transcripts decreased in abundance by 2- to 3-fold from E19 to 42 d in ileum (p less than 0.05). The abundance of both transcripts was three to 10 times greater in 60-d liver than in the other three tissues at 60 d.(ABSTRACT TRUNCATED AT 250 WORDS)
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Tissue-specific developmental regulation of the messenger ribonucleic acids encoding the Growth hormone receptor and the Growth hormone binding Protein in rat fetal and postnatal tissues.
Pediatric Research, 1992Co-Authors: J L Walker, B M Moats-staats, A D Stiles, L E UnderwoodAbstract:ABSTRACT: Tissue responsiveness to Growth hormone is likely to be regulated by local concentrations and availability of the membrane-bound Growth hormone receptor (GHR) and perhaps by the actions of the soluble Growth hormone binding Protein (GHBP). To determine whether the developmental regulation of the GHR and GHBP might vary among tissues, we have measured the relative abundance of the 4.3-kb GFR and 1.3-kb GHBP mRNA in rat fetal and postnatal liver, kidney, lung, and ileum by Northern hybridization of polyadenylated RNA with a 32P-labeled antisense riboprobe prepared from a rat GHR cDNA. The GHR and GHBP mRNA were both present in the four tissues studied at fetal age 19 d (E19). In postnatal liver, both transcripts increased in abundance 3− to 4-fold after 14 d to mature levels at 42 d (p = 0.0001). Similar changes were seen in postnatal kidney for GHR mRNA abundance; however, GHBP mRNA abundance increased only 2− to 3-fold to mature levels by 28 d (kidney GHR versus GHBP mRNA profile, p = 0.0001). In lung, a 2-fold linear increase in GHR mRNA abundance was observed (p = 0.0019), but the GHBP mRNA did not change (GHR versus GHBP mRNA profile, p = 0.0006). Both transcripts decreased in abundance by 2− to 3-fold from E19 to 42 d in ileum (p < 0.05). The abundance of both transcripts was three to 10 times greater in 60-d liver than in the other three tissues at 60 d. The variation in abundance and in the developmental profiles of the GHR and GHBP mRNA observed in these fetal and postnatal tissues suggests that the GHR and GHBP could mediate differences within and between tissues in the responsiveness to Growth hormone. The differential regulation of the two transcripts evident in kidney and lung supports the emerging evidence that the GHBP may have a funciton distinct from that of the GHR.
Marie-catherine Postel-vinay - One of the best experts on this subject based on the ideXlab platform.
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Regulation of human Growth hormone receptor gene transcription by human Growth hormone binding Protein
Molecular and cellular endocrinology, 1997Co-Authors: Primus-eugen Mullis, Johannes K Wagner, Andrée Eblé, Jean-marc Nuoffer, Marie-catherine Postel-vinayAbstract:Abstract The hypothesis that Growth hormone binding Protein (GHBP) has an effect on its own on the regulation of the GH-receptor/GHBP transcription was tested. Three different forms of human GHBP (recombinant non-glycosylated GHBP, recombinant glycosylated GHBP and GHBP purified and extracted from serum) were added in different concentrations determined by LIFA [0 pmol/l; 50 pmol/l (low level), 200 pmol/l (average level) and 500 pmol/l (high level in circulation)] to a human hepatoma cell line (HuH7 cells) cultured in a serum free hormonally-defined medium. Following the incubation with GHBP for 0, 1 and 2 h, GH-receptor expression was quantitatively assessed by using polymerase chain reaction amplification. Treatment with a GHBP concentration of 50 pmol/l resulted in a significant increase of GH-receptor mRNA molecules given as number of molecules×10 6 / μ g total RNA. In contrast, the concentration of 500 pmol/l presented a significant decrease of GH-receptor mRNA molecules, whereas 200 pmol/l GHBP produced a GH-receptor gene expression which was in between the values of the experiments with 50 and 500 pmol/l of GHBP added. Furthermore, the three different forms of human GHBP used provided similar data and, therefore, did not effect in any variation of GH-receptor expression. In addition, nuclear run-on experiments confirmed the changes in GH-receptor expression; and cycloheximide (10 μ g/ml) did not alter the transcription indicating that the up and down regulating effects of GHBP on the GH-receptor/GHBP gene transcription was dependent, at least partly, on pre-existing factors and does not require Protein synthesis. In conclusion, we present data showing that GHBP on its own has an effect on GH-receptor gene expression.
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Growth Hormone-Binding Protein in the goat: characterization, evolution under exogenous Growth hormone treatment, and correlation with liver Growth hormone receptor levels
Domestic animal endocrinology, 1996Co-Authors: Hélène Jammes, Marie-catherine Postel-vinay, C. Disenhaus, V. Ouriet, Christine Kayser, Jean DjianeAbstract:This report describes the identification and characterization of a specific, high-affinity Growth Hormone-Binding Protein (GHBP) in lactating goat serum. Serum samples were incubated with [125I]human GH as ligand and in the absence or in the presence of bovine GH as competitor. GH-GHBP complex formation was performed by high-performance liquid chromatography, and the radioactivity was recorded on-line with a Berthold LB detector connected to a computer. The results showed that a serum Protein was able to bind specifically to human GH and bovine GH but not to ovine prolactin. Scatchard plots indicated an affinity constant of 4.5 x 10(8) M-1 and a maximum binding capacity of 4.8 x 10(-10) mol/l. In addition, we conducted a 4-wk study to determine the effects of recombinant bovine GH administration on milk production in lactating goats. The effects of recombinant bovine GH treatment on milk production and on the regulation of GHBP and hepatic GH receptor levels were studied. As expected, recombinant bovine GH injected daily increased yields of milk, fat, Protein (40, 61, and 40%, respectively), and circulating insulin-like Growth factor 1 concentrations compared with controls. During the pretreatment and treatment periods, the control goats exhibited a constant amount of GHBP in serum. No consistent effect of GH treatment on GHBP level was observed. The binding of [125I]bovine GH to hepatic microsomal membranes of GH-treated goats was significantly decreased compared with that of control goats. After MgCl2 desaturation of membranes, the results demonstrated that the down-regulation of GH hepatic receptors, observed for the treated goat group, was induced by receptor occupancy without modification of binding affinity. The GH receptor gene expression, analyzed by slot blot and hybridization with an [alpha-32P]GH receptor cDNA probe, was not modified by the GH treatment. In lactating goats, the galactopoietic effect of exogenous GH involved a hepatic receptor occupancy. The individual concentration of GHBP in serum cannot explain the individual variations of responses to GH treatment in goats.
Serge Amselem - One of the best experts on this subject based on the ideXlab platform.
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Evolutionary divergence of the truncated Growth hormone receptor isoform in its ability to generate a soluble Growth hormone binding Protein.
Molecular and cellular endocrinology, 1998Co-Authors: Florence Dastot, Philippe Duquesnoy, Marie-laure Sobrier, Michel Goossens, Serge AmselemAbstract:The soluble Growth hormone binding Protein (GHBP), which is encoded by the GH receptor (GHR) gene, is generated by several mechanisms. In rabbits (rb) and humans (h), it is derived by proteolytic cleavage of the full-length membrane-bound receptor molecules (GHR-fl), whereas in rats (r) and mice, it results from an alternative splice excluding the transmembrane domain. Furthermore, in all these species, alternative splicing in the cytoplasmic domain results in a truncated isoform (GHR-tr), that, in humans, produces large amounts of GHBP through proteolysis. To further characterize the species specificity of the mechanism underlying GHBP generation, rbGHR-tr and rGHR-tr expressed in COS-7 cells were assayed for their ability to produce a GHBP in comparison with the corresponding full-length receptors. Large amounts of GHBP were secreted by cells expressing the rabbit constructs, the rbGHR-tr isoform being more efficient in GHBP generation than rbGHR-fl. In contrast, no GHBP was detected from cells expressing rGHR-tr, the cytoplasmic deletion having no effect on GHBP release from membrane receptors. These data further demonstrate evolutionary divergence in the mechanism by which GHBP is generated and provide new clues to decipher the molecular process underlying the cleavage step.
