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Differential developmental expression of the rat kininogen genes
1Department of Pediatrics, Tulane University School of Medicine, New Orleans, Louisiana 70112.
Pediatric Research
|December 1, 1992
Summary
Rat liver T-kininogen (T-KG) mRNA levels significantly increase after birth, suggesting a protective role via antiprotease activity. Kininogen K (K-KG) expression remains constant throughout development.
Area of Science:
- Biochemistry
- Developmental Biology
- Molecular Genetics
Background:
- Rat liver expresses two low molecular weight kininogens: T-kininogen (T-KG) and K-kininogen (K-KG).
- T- and K-KG genes exhibit differential regulation despite sequence similarity in flanking regions.
- T-KG is inducible and functions as a thiol-protease inhibitor, while K-KG is constitutive and a bradykinin precursor.
Purpose of the Study:
- To investigate the differential developmental expression of T- and K-KG genes in Sprague-Dawley rats.
- To understand the regulatory mechanisms governing kininogen gene expression during rat development.
Main Methods:
- Northern blot analysis of total liver RNA to detect T- and K-KG mRNA species.
- High-stringency probing with complementary oligonucleotides.
- Western blot analysis to assess T-KG protein levels in liver and plasma.
Main Results:
- A single T-KG mRNA (1.8 kb) and two K-KG mRNA species (1.6 and 2.3 kb) were detected across all ages.
- Steady-state T-KG mRNA levels increased 3.5-fold at birth, remaining high for the first week before declining.
- T-KG protein levels paralleled mRNA expression, while K-KG mRNA expression showed no significant changes during fetal to neonatal transition or postnatal maturation.
Conclusions:
- Rat liver synthesizes kininogens during fetal development.
- T- and K-KG genes are differentially regulated during postnatal development.
- Postnatal up-regulation of T-KG synthesis may provide a protective function in newborns through its antiprotease activity.