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Glutamine synthetase expression in perinatal spiny mouse liver
W H Lamers1, L Boon, F J Van Hemert
1Department of Anatomy and Embryology, Academic Medical Center, University of Amsterdam, The Netherlands. w.h.lamers@amc.uva.nl
European Journal of Biochemistry
|July 20, 1999
Summary
Post-transcriptional gene regulation increases ammonia-metabolizing enzymes in perinatal liver. This study reveals protein synthesis regulation at the elongation level, crucial for perinatal adaptation in spiny mice.
Area of Science:
- Biochemistry
- Molecular Biology
- Developmental Biology
Background:
- Post-transcriptional control significantly impacts gene expression, particularly for ammonia-metabolizing enzymes during the perinatal period.
- The mechanisms and adaptive significance of increased protein/mRNA ratios in rat liver remain unclear.
Purpose of the Study:
- Investigate the regulation of glutamine synthetase (GS) gene expression in spiny mouse liver.
- Compare rat and spiny mouse to distinguish adaptive from developmental regulation.
- Elucidate the molecular mechanisms controlling GS protein accumulation during the perinatal phase.
Main Methods:
- Quantified GS enzyme activity and protein content via Western blot.
- Measured GS mRNA levels using molecular assays.
- Analyzed polysome profiles to assess translational control mechanisms.
Main Results:
- GS enzyme activity and protein content increased exponentially both prenatally and postnatally.
- GS mRNA levels decreased postnatally, leading to a significant increase in the protein/mRNA ratio.
- Polysome profiling indicated GS mRNA was fully occupied by ribosomes, suggesting regulation at the elongation step.
Conclusions:
- Perinatal adaptation involves a substantial increase in GS protein synthesis rate, driven by enhanced translational elongation.
- This regulation occurs post-transcriptionally, primarily at the level of translation, not mRNA stability or initiation.
- Spiny mouse serves as a model to understand adaptive perinatal gene expression control.