Positional and developmental regulation of glutamine synthetase expression in mouse liver.

In situ hybridization showed that all fetal hepatocytes contain glutamine synthetase (GS) mRNA but that in adult mouse liver, only a single cell layer surrounding the central veins contains GS mRNA. A shift from the fetal to the adult pattern begins within a few days of birth and is complete within 12 days of birth. Since the total GS mRNA and the transcription rate of the single GS gene are similar at birth and in adults, we conclude that there is a generalized reduction in GS transcription for most hepatocytes and a sharp rise in GS transcription for the immediate pericentral cells. This may be a case of positional regulation of specific gene transcription in apparently a single cell lineage.