Regulation of mouse retinol dehydrogenases and retinal dehydrogenases in hepatocyte differentiation.

Retinoic acid (RA) is produced via two sequential reactions of retinol dehydrogenases (RDHs) and retinal dehydrogenases (RALDHs). We found that primary cultured mouse hepatocytes on a single collagen gel gradually lost hepatocyte specific morphology, and that another collagen gel overlay remarkably recovered it. The levels of albumin and liver-dominant expressed RDHs expression in hepatocytes paralleled their morphological change, decreased during single collagen gel culture, and were up-regulated by sequential collagen overlay. Quite similar to the expression changes, albumin and those RDHs' mRNA expression levels increased along with liver differentiation during pre- and postnatal liver development. Our data supports that all-trans and 9-cis RA, catalyzed by the RDHs, indeed play an important role in liver differentiation and regeneration.