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Distribution and relevance of insulin-like growth factor-I receptor in metanephric development
1Department of Pathology, Northwestern University Medical School, Chicago, Illinois.
Abstract:
During embryogenesis, various ligand-receptor interactions take place to modulate the development and growth of various mammalian organs. During these interactions, a critical concentration of a given receptor is needed to elicit a ligand-induced biologic response at a defined gestational stage of the fetus. In this study, the distribution and the relevance of insulin-like growth factor-I receptor (IGF-IR) in metanephric development was investigated. Kidneys were harvested from mouse embryos at days 13 to 19 of fetal gestation, and maintained in a metanephric culture system. Immunofluorescence studies, using anti-IGF-IR, revealed a high expression of IGF-IR at day 13, which declined during the later stages of gestation through neonatal life. To study the relevance of IGF-IR expression in metanephric development, antisense-oligodeoxynucleotide (ODN) experiments were carried out. Antisense-ODN 43 mer probes were synthesized utilizing rat IGF-IR cDNA selected nucleotide sequences which are highly conserved in other mammalian species. Southern blot analyses of various restriction fragments of the rat and mice genomic DNA yielded similar bands when hybridized with the antisense-ODN or rat IGF-IR cDNA, suggesting a high degree of homology in the region of the gene selected for the synthesis of antisense-ODN. Also, the antisense-ODN hybridized with the appropriate murine fetal kidney mRNA species, as ascertained by S1 nuclease protection assay. Inclusion of antisense-ODN in the culture medium resulted in an inhibition of the growth of the kidney, reduction in the population of the nephrons and disorganization of the ureteric bud branches.(ABSTRACT TRUNCATED AT 250 WORDS)
Insights
Insulin-like growth factor-I receptor (IGF-IR) is crucial for kidney development. Blocking IGF-IR in embryonic kidneys inhibits growth and nephron formation, highlighting its essential role.
Area of Science:
- Developmental Biology
- Molecular Biology
- Genetics
Background:
- Embryonic development relies on precise ligand-receptor interactions.
- Specific receptor concentrations are vital for fetal organogenesis at defined gestational stages.
Purpose of the Study:
- To investigate the distribution and functional relevance of insulin-like growth factor-I receptor (IGF-IR) during mammalian kidney development.
Main Methods:
- Immunofluorescence staining of embryonic mouse kidneys (gestational days 13-19) to detect IGF-IR expression.
- In vitro metanephric culture system with antisense-oligodeoxynucleotides (ODN) to inhibit IGF-IR.
- Southern blot and S1 nuclease protection assays to confirm antisense-ODN specificity and homology.
Main Results:
- IGF-IR expression was high at day 13 of gestation, decreasing in later stages.
- Antisense-ODN targeting IGF-IR significantly inhibited embryonic kidney growth.
- Inhibition of IGF-IR led to reduced nephron populations and disorganized ureteric bud branching.
Conclusions:
- IGF-IR plays a critical role in regulating mammalian kidney development.
- Blocking IGF-IR function disrupts key developmental processes, including nephrogenesis and ureteric branching.