Rat liver transcript profiling in normal and disease states using a kinetic polymerase chain reaction assay

Synthesis of a number of rat liver proteins, including albumin, fibrinogen, apolipoprotein AI, and transferrin, is elevated in the nephrotic syndrome (NS). Increased synthesis of these proteins is regulated at the transcriptional level and occurs in the context of increased mRNA encoding each protein. Changes in albumin, fibrinogen, apolipoprotein AI, and transferrin mRNA levels in total cellular RNA isolated from the livers of normal rats and rats with passive Heymann nephritis were measured using a kinetically monitored, reverse transcriptase-initiated PCR (kRT-PCR) assay. The kRT-PCR assay rapidly quantitated changes in rat liver mRNA levels with an accuracy comparable to that of more labor-intensive mRNA quantitation methods. The relative levels of beta-actin, apolipoprotein AI, fibrinogen, and albumin mRNAs were very similar in total cellular RNA isolated from rat liver versus H4C3 hepatocytes in culture, suggesting that the H4C3 hepatocyte is an appropriate model for studying expression of genes encoding proteins secreted by the liver. Taken together, the results demonstrate the feasibility of using the kRT-PCR assay for isolation and characterization of a soluble factor responsible for elevated synthesis of hepatocyte mRNAs associated with the nephrotic syndrome.