Changes in apolipoprotein A-I mRNA level in the liver of rats with experimental nephrotic syndrome.
In previous studies we had shown that: one of the most specific feature of hyperlipoproteinemia found in rats with experimental nephrotic syndrome is the accumulation of apolipoprotein A-I-rich HDL in plasma and this disorder is associated with an overproduction of apolipoprotein A-I by the liver. The present study was designed to investigate whether the increased hepatic synthesis of apolipoprotein A-I was due to an accumulation of functionally active apolipoprotein A-I mRNA in liver of nephrotic rats. Hepatic mRNA was translated in vitro by rabbit reticulocyte lysate in the presence of [35S]methionine and in vitro synthesized apolipoprotein A-I, albumin and apolipoprotein E were immunoprecipitated by specific rabbit IgG. In nephrotic rats the amount of in vitro synthesized apolipoprotein A-I was almost twice that found in the controls, suggesting that functionally active apolipoprotein A-I mRNA was increased in liver of nephrotic rats. To confirm that this difference in apolipoprotein A-I mRNA activity was due to an actual increase of hepatic apolipoprotein A-I mRNA sequences, we performed nucleic acid hybridization experiments (northern blot) using several cloned cDNA probes (rat and human apolipoprotein A-I, rat apolipoprotein E and apolipoprotein A-II). The results indicate that in nephrotic rats the amount of hybridizable apolipoprotein A-I mRNA sequences was about 3-fold higher than that in controls. In contrast, there was no difference in the amount of hybridizable apolipoprotein A-II and apolipoprotein E mRNA sequences, indicating that the change in apolipoprotein A-I mRNA induced by the nephrotic state was specific for this mRNA.
D000818:Animals; D016632:Apolipoprotein A-I; D001054:Apolipoproteins A / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D001057:Apolipoproteins E / Q000235:genetics / Q000302:isolation & purification; D002474:Cell-Free System; D008099:Liver / Q000032:analysis*; D008297:Male; D009404:Nephrotic Syndrome / Q000378:metabolism*; D009693:Nucleic Acid Hybridization; D011061:Poly A / Q000378:metabolism; D014176:Protein Biosynthesis; D012313:RNA / Q000378:metabolism; D012333:RNA, Messenger / Q000032:analysis* / Q000235:genetics; D051381:Rats; D011919:Rats, Inbred Strains; D012709:Serum Albumin / Q000302:isolation & purification
D016632:Apolipoprotein A-I; D001054:Apolipoproteins A; D001057:Apolipoproteins E; D012333:RNA, Messenger; D012709:Serum Albumin; D011061:Poly A; D012313:RNA