THE GENE OF HEPATOCYTE GROWTH-FACTOR IS EXPRESSED IN FAT-STORING CELLS OF RAT-LIVER AND IS DOWN-REGULATED DURING CELL-GROWTH AND BY TRANSFORMING GROWTH-FACTOR-BETA

Hepatocyte growth factor (HGF) has been detected in non-parenchymal cells but not in hepatocytes. We performed Northern blot analysis of total RNA extracted from rat hepatocytes, Kupffer cells, endothelial cells and fat-storing (Ito-) cells. Total RNA was extracted from fat-storing cells at different times after isolation and from cells treated with different amounts of transforming growth factor β. The RNA was hybridized with HGF, fibronectin-, and α-actin-specific cDNA probes, consecutively. We found an abundant amount of HGF mRNA in freshly isolated fat-storing cells, but not in other liver cells. The amount of the HGF transcripts decreases significantly in FSC during the time of culture, while fibronectin gene expression increases and α-actin gene expression as well. TGF-β dramatically inhibits HGF gene expression, but causes an enhanced fibronectin mRNA level. Northern blot hybridisation of total RNA from CCl4-chronically damaged liver with HGF cDNA shows a significant increase of HGF mRNA during development of liver fibrosis. We suggest that in damaged liver either non-parenchymal cells, others than FSC, became able to express the HGF in vivo, or other mediators overcome the inhibitory effect of TGF-β. © 1992.