Correlation between acute phase-related expression of C/EBP beta and transcriptional regulation of the haptoglobin gene during rat liver development

The hepatic 35 kD nucleoprotein participates in transcriptional regulation of the haptoglobin gene during the development of rat liver. The same molec ular mass and trans-acting role of the above protein as the active isoform of C/EBP beta transcription factor, made homology between them possible. We could detect C/EBP beta in control hepatic nuclear extracts not earlier th an in the second week after the birth. However, the acute-phase reaction in duced the expression of 35 kD-C/EBP beta at day 7 of postnatal development suggesting that the above trans-active nucleoprotein displays the structura l and functional characteristics of C/EBP beta isoform from that day on.