scholarly journals Fetal rat lung epithelium has a functional growth hormone receptor coupled to tyrosine kinase activity and insulin-like growth factor binding protein-2 production

1998 ◽  
Vol 21 (1) ◽  
pp. 73-84 ◽  
Author(s):  
DC Batchelor ◽  
RM Lewis ◽  
BH Breier ◽  
PD Gluckman ◽  
SJ Skinner
Keyword(s):  
Growth Hormone ◽  
Growth Factor ◽  
Binding Protein ◽  
Fetal Lung ◽  
Mrna Levels ◽  
Insulin Like Growth Factor ◽  
Rat Lung ◽  
Lung Epithelium ◽  
Fetal Rat ◽  
Fetal Rat Lung

Although growth hormone (GH) receptor (GHR) mRNA and protein are present in fetal tissues such as the lung, there is little evidence that GH mediates growth in the fetus. We have identified functional responses to GH in fetal rat lung epithelia and suggest a possible role for GHR in the developing lung. GHR mRNA in lung extracts was high before birth at day 16 of gestation (16f), decreased to low levels at day 22f but increased again after birth. At day 20f GHR mRNA levels were higher in lung than in liver, whereas growth hormone binding protein mRNA levels were approximately equal in lung and liver. Stimulation of primary cell cultures of day 19f lung epithelia with GH caused increased tyrosine phosphorylation in specific proteins, demonstrating functional GHR. Lung fibroblasts isolated at the same time did not respond to GH. Ligand and Northern blot analysis of the epithelial cultures revealed that GH stimulation increased insulin-like growth factor binding protein-2 (IGFBP-2) activity and mRNA. These experiments demonstrate the functional activity of GHR, specifically in fetal lung epithelium. We suggest that one role for GH in vivo may be indirectly to modify insulin-like growth factor activity in the developing fetal lung by increasing IGFBP-2.

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 and developmental regulation of wnt-2 (irp) gene in mesenchymal cells of fetal lung

1992 ◽  
Vol 262 (6) ◽  
pp. L672-L683 ◽  
Author(s):  
B. K. Levay-Young ◽  
M. Navre
Keyword(s):  
Lung Development ◽  
Developmental Regulation ◽  
Fetal Lung ◽  
Fibroblast Cell ◽  
Mrna Levels ◽  
Rat Lung ◽  
Intercellular Interaction ◽  
Wnt Proteins ◽  
Fetal Rat ◽  
Fetal Rat Lung

The wnt gene family encodes a group of proteins implicated as intercellular signaling molecules in vertebrate development. Because many wnt genes are also expressed in the lung, we have examined whether the wnt family member wnt-2 (irp) plays a role in lung development. We have cloned rat wnt-2 and found that this cDNA detects multiple mRNAs expressed at high levels in fetal rat lung. Much lower levels were found in adult rat lung and other tissues, including, surprisingly, the mammary gland. The wnt-2 mRNA was also detected in human fetal lung fibroblast cell lines, where the mRNA levels were dramatically regulated by growth state as well as growth factor stimulation. In situ hybridization showed that, in fetal rat lung, wnt-2 mRNA expression is restricted to the mesenchyme; levels in the developing epithelium were indistinguishable from background. Based on the known properties of other wnt proteins, our data lead us to propose that wnt-2 may play a role in lung development by mediating intercellular interaction(s) between mesenchyme and epithelium.

scholarly journals Mechanical strain-induced posttranscriptional regulation of fibronectin production in fetal lung cells

1999 ◽  
Vol 277 (1) ◽  
pp. L142-L149 ◽  
Author(s):  
Eric Mourgeon ◽  
Jing Xu ◽  
A. Keith Tanswell ◽  
Mingyao Liu ◽  
Martin Post
Keyword(s):  
Cell Proliferation ◽  
Mechanical Strain ◽  
Fetal Lung ◽  
Northern Analysis ◽  
Normal Lung ◽  
Lung Cells ◽  
Mrna Levels ◽  
Rat Lung ◽  
Fetal Rat ◽  
Fetal Rat Lung

We have shown that intermittent mechanical strain, simulating fetal breathing movements, stimulated fetal rat lung cell proliferation. Because normal lung growth requires proper coordination between cell proliferation and extracellular matrix remodeling, we investigated the effect of strain on fibronectin metabolism. Organotypic cultures of fetal rat lung cells, subjected to intermittent strain, showed increased fibronectin content in the culture media. Fibronectin-degrading activity in media from strained cells was similar to that of static cultures. Northern analysis revealed that strain inhibited fibronectin mRNA accumulation seen during static culture. Synthesis of fibronectin, determined by metabolic labeling, was increased by strain despite lower mRNA levels or presence of actinomycin D. This increase was not mediated via a rapamycin-sensitive mechanism. Strain stimulated prelabeled fibronectin secretion even in the presence of cycloheximide. These results suggest that strain differentially regulates fibronectin production of fetal lung cells at the transcriptional and posttranscriptional levels. Mechanical strain increases soluble fibronectin content by stimulating its synthesis and secretion without increasing fibronectin message levels.

Growth Hormone-Releasing Factor Regulation by Somatostatin, Growth Hormone and Insulin-Like Growth Factor I in Fetal Rat Hypothalamic-Brain Stem Cell Cocultures

1993 ◽  
Vol 58 (6) ◽  
pp. 655-665 ◽  
Author(s):  
Gumersindo Fernández Vázquez ◽  
Luanda Cacicedo ◽  
Maria Teresa de los Frailes ◽  
Maira Jesús Lorenzo ◽  
Rosa Tolón ◽  
...  
Keyword(s):  
Growth Hormone ◽  
Stem Cell ◽  
Growth Factor ◽  
Brain Stem ◽  
Insulin Like Growth Factor ◽  
Growth Hormone Releasing Factor ◽  
Factor I ◽  
Fetal Rat ◽  
Growth Factor I
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