Related Experiment Videos
Identification and characterization of growth hormone receptor mRNA in the mammary gland
1Unité d'Endocrinologie Moléculaire, Institut National de la Recherche Agronomique, Jouy, France.
Abstract:
The present report describes the first characterization of growth hormone (GH) receptor (GH-R) mRNA in the rabbit mammary gland. Northern blot analysis of poly(A)+ RNA isolated from several tissues of rabbit probed with a rabbit liver GH-R cDNA fragment revealed hybridization to only one transcript of 4.2 kb. A specific hybridizing signal appears in the mammary gland mRNA during gestation, when three different probes derived from liver GH-R cDNA and encoding respectively for extracellular, transmembrane and intracellular regions, were used. The signal is lower than in the liver but highly significant. These results indicate that the three regions are present and well conserved in the GH-R transcript found in the mammary gland. By S1 nuclease mapping analysis we demonstrated that the extracellular and transmembrane domains of mammary gland GH-R mRNA are strongly homologous to the liver GH-R mRNA. In addition, mammary gland GH-R mRNA is probably generated by mammary epithelial cells as demonstrated by the hybridization signal obtained using mRNA extracted from purified acini. The increase in the concentration of GH-R mRNA occurs during epithelial cell proliferation associated with a decrease in the proportion of adipocytes and connective cells at late gestation. The 4.2 kb GH-R mRNA species was also detected in ovine and porcine mammary glands during gestation, suggesting a probable expression of the related form of GH-R in these species.
Insights
Researchers identified growth hormone (GH) receptor (GH-R) mRNA in rabbit mammary glands during gestation. This GH-R mRNA is likely produced by mammary epithelial cells and conserved across species.
Area of Science:
- Reproductive Biology
- Molecular Endocrinology
- Mammalian Physiology
Background:
- Growth hormone (GH) plays a crucial role in mammary gland development and function.
- The presence and regulation of the GH receptor (GH-R) in the mammary gland are not fully understood.
- Characterizing GH-R mRNA expression provides insights into GH signaling during lactation.
Purpose of the Study:
- To characterize growth hormone receptor (GH-R) mRNA in the rabbit mammary gland.
- To determine the expression pattern and cellular origin of GH-R mRNA during gestation.
- To investigate the conservation of GH-R mRNA structure and expression in other species.
Main Methods:
- Northern blot analysis of poly(A)+ RNA from various rabbit tissues.
- Hybridization using rabbit liver GH-R cDNA probes (extracellular, transmembrane, intracellular regions).
- S1 nuclease mapping to analyze mRNA domains and cellular localization via purified acini mRNA.
Main Results:
- A 4.2 kb GH-R mRNA transcript was detected in rabbit mammary gland during gestation.
- The mammary gland GH-R mRNA shows high homology to liver GH-R mRNA, particularly in extracellular and transmembrane domains.
- GH-R mRNA expression increased with epithelial cell proliferation during late gestation.
- Similar GH-R mRNA species were found in ovine and porcine mammary glands.
Conclusions:
- The rabbit mammary gland expresses a 4.2 kb GH-R mRNA transcript during gestation.
- This transcript is likely produced by mammary epithelial cells and shares conserved domains with the liver GH-R.
- GH-R mRNA expression correlates with epithelial cell proliferation, suggesting a role in mammary gland development.