Developmental Changes in Apolipoprotein B Gene Expression in the Liver of Fetal Calves

Abstract

Changes in apolipoprotein (apo B) gene expression in the liver were determined in fetal calves from 90 to 260 days of intrauterine life. Results were compared with those obtained from the livers of 1-month-old calves and adult cows. By Western blot analysis using a rabbit antiserum to bovine apo B, apo B100 was detected from 90 days of intrauterine life. Apo B100 was shown to be the only form of apo B detected in the liver of fetal calves whatever the gestational age indicating the lack of editing process during the prenatal period. Hepatic apo B contents were stable during intrauterine life and comparable to those of calves and lower than those of cows. Hepatic contents of apo B mRNA increased with the gestational age similarly to total RNA. Values of apo B mRNA at 260 days of intrauterine life were comparable to those in the liver of 1-month-old calves and adult cows. These results suggested that hepatic synthesis of calf apo B during fetal development is specifically regulated at a posttranscriptional level, either by a decrease in the rate of translation and/or by an increase in the rate of intracellular apo B degradation.

Effects of interactions of hepatocyte nuclear factor 4α isoforms with coactivators and corepressors are promoter‐specific

“…Specific deletion of HNF4α in adult liver results in complete loss of ApoCIII expression [20]. Furthermore, the levels of ApoB and ApoCIII transcripts increase during development to reach the levels characteristic of adult liver [27]. Thus, the transcriptional responses that we have obtained using promoter studies recapitulate those observed during development: expression is lower during embryonic/fetal life when the less responsive HNF4α7 isoform is expressed.…”