Hepatic Gene Expression During the Perinatal Transition in the Rat

Area of Science:

• Developmental Biology
• Molecular Biology
• Genomics

Background:

• The liver is critical for energy metabolism and macromolecule synthesis during the perinatal transition.
• Understanding hepatic gene expression changes in the early postnatal period is essential for comprehending perinatal adaptation.

Purpose of the Study:

• To characterize dynamic changes in hepatic gene expression in rats from late gestation through the first postnatal week.
• To identify key metabolic pathways and regulatory networks involved in the immediate perinatal transition.

Main Methods:

• RNA microarrays were employed to profile gene expression.
• Computational analyses were used to identify significant changes and upstream regulators.
• Gene expression was analyzed at multiple time points: embryonic day 21, 30 min, 4 h, 12 h, 1 day, and 1 week postnatally.

Main Results:

• Marked hepatic gene expression changes occurred between 4 and 12 hours after birth, impacting glycolysis and cholesterol synthesis.
• Over 50% of nuclear-encoded mitochondrial genes altered expression within the first week, with 25% changing in the first 24 hours.
• Changes coincided with hepatocyte proliferation and were linked to cell stress, hormones, cytokines, and transcription factor networks.

Conclusions:

• Early postnatal hepatic gene expression involves a complex, choreographed network of signaling pathways responding to environmental stimuli.
• The transcriptomic response facilitates a complex metabolic adaptation during the perinatal period.
• Multiple initiating factors and transcriptional regulators orchestrate this adaptive response.