Dependence of hepatocyte-specific gene expression on cell-cell interactions in primary culture.

Abstract

In co-culture with non-parenchymal liver epithelial cells, rat hepatocytes show a marked increase in albumin and total protein synthesis when compared with cells maintained as pure populations in which an early decline in albumin secretion takes place. Analysis of the relative amounts of different mRNA sequences, determined by hybridization, indicated that the increase in protein synthesis resulted essentially from an increased level of the corresponding mRNAs. In addition, when cell-cell contacts were established between the two cell types several days after the seeding of hepatocytes, the stimulation of albumin secretion was similarly observed with a significant increase of the corresponding mRNA on days 10-14 of culture. Transcriptional assays, in which isolated nuclei were used for the study of RNA synthesis, showed that liverspecific gene transcription was significantly increased and maintained for at least 2 weeks. These results demonstrate for the first time long-term stabilization and reversibility of various specific mRNAs at high levels by adult hepatocytes in primary culture. They suggest that establishment of cellcell contacts between hepatocytes and liver epithelial cells are essential for the maintenance of a high rate of transcription of the liver-specific genes.

Advantages of in vitro cytotoxicity testing by using primary rat hepatocytes in comparison with established cell lines.

“…Similar changes are observed for Phase II enzymes (Forster et al,1986;Vandenberghe et al,1988). Other liver-specific genes such as albumin and transferrin in vitro may fall to less than 10% of their transcription rate in vivo (Clayton and Darnell, 1983;Fraslin et al, 1985). Various investigators are continuing to work on a further and better understanding of the molecular basis of the above process, and new hepatocyte cell lines have been developed (Werner et al, 1999;Allen et al, 2000;Kobayashi et al, 2000;Lee et al, 2000) in an effort to minimize the limitations of primary cultured hepatocytes.…”

Increase of β‐actin mRNA upon hypotonic perfusion of perfused rat liver

“…Thereafter, liver cell volume has reached a new steady state, which is 16.5+2.6% above the volume during normotonic perfusion [1 I], so that cells are exposed to mechanical stress. The elevated level offl-actin mRNA is significant at 1 h and is interpreted as a cellular response to the persistent mechanical stress resulting from cell swelling, fl-Actin mRNA has been reported to be induced during cell damage by various agents [12,13] as well as during establishment of hepatocytes in primary cultures [14]. Interestingly, in the latter case the effect was about 3-fold, similar to that in hypotonically perfused livers (Table I, Figs.…”

Liver cell models in in vitro toxicology.

“…UDP-glucuronyltransferase activity is more stable than that of sulfotransferases (66). The loss of specific functions is associated with an early drop of transcription rates of liver-specific genes, e.g., albumin and transferrin, that represent only 1 to 10% of those found in the liver after 24 hr of culture (68,69).…”