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Expression of liver carnitine palmitoyltransferase I and II genes during development in the rat
S Thumelin1, V Esser, D Charvy
1Centre de Recherche sur l'Endocrinologie Moléculaire et le Développement du CNRS, Meudon-Bellevue, France.
Insights
Hepatic carnitine palmitoyl-transferase I (CPT I) expression and activity increase after birth and are influenced by diet. CPT II expression remains high throughout development, unaffected by nutritional status.
Area of Science:
- Biochemistry
- Molecular Biology
- Developmental Biology
Background:
- Hepatic carnitine palmitoyl-transferases (CPT) I and II are key enzymes in fatty acid oxidation.
- Their regulation is crucial for energy homeostasis, especially during developmental transitions and varying nutritional states.
Purpose of the Study:
- To investigate the developmental expression and activity of hepatic CPT I and CPT II in rats.
- To determine the impact of nutritional state (weaning diet, fasting) on CPT I and CPT II regulation.
Main Methods:
- Enzyme activity assays.
- Western blotting for protein expression.
- Quantitative real-time PCR for mRNA levels.
- Studies conducted on rat liver during neonatal development, weaning, and adult fed-starved transitions.
Main Results:
- CPT I activity, protein, and mRNA are low in fetal liver, increasing significantly post-birth.
- CPT I expression is high during suckling, in rats weaned onto high-fat diets, and in starved adults.
- High-carbohydrate weaning significantly decreases CPT I expression.
- CPT II activity, protein, and mRNA are high in fetal liver and remain elevated regardless of nutritional status.
Conclusions:
- CPT I expression is dynamically regulated by nutritional cues during development and in adulthood.
- CPT II exhibits a stable, high basal expression in the liver, independent of nutritional state.
- These findings highlight differential regulation of CPT I and CPT II in response to metabolic demands.
Abstract:
The enzyme activity and the expression (protein and mRNA concentrations) of genes encoding for hepatic carnitine palmitoyl-transferases (CPT) I and II were studied during neonatal development, in response to nutritional state at weaning and during the fed-starved transition in adult rats. The activity, the protein concentration and the level of mRNA encoding CPT I are low in foetal-rat liver and increase 5-fold during the first day of extra-uterine life. The activity and gene expression of CPT I are high during the entire suckling period, in the liver of 30-day-old rats weaned at 20 days on to a high-fat diet and in the liver of 48 h-starved adult rats. The activity and CPT I gene expression are markedly decreased in the liver of rats weaned on to a high-carbohydrate diet. By contrast, the activity, the protein concentration and the level of mRNA encoding CPT II are already high in the liver of term foetuses and remain at this level throughout the suckling period, irrespective of the nutritional state of the animals either at weaning or in the adult.