Thyroid hormone responsive genes in the murine hepatocyte cell line AML 12

Thyroid hormone (T3) plays an important role in gene regulation in the liver. Previous studies have been done in complex systems such as animal models, or in transformed malignant hepatic cell lines in which thyroid hormone receptor (TR) was over-expressed by co-transfection. Therefore, the aim of this study was to characterize T3-responsive genes in a simple system, by using a non-transformed hepatic cell line that is able to express sufficient amounts of endogenous TRs. For this purpose we used the murine non-transformed hepatocyte cell line AML 12. We performed analyses using a cDNA microarray containing 15,000 murine genes. We found 12 genes to be up-regulated and 5 genes to be down-regulated in the presence of T3. For some of the genes not previously known to be regulated by T3, we confirmed the regulation by T3 using real-time PCR. Our data in AML 12 cells provide a simple and physiologically relevant system to study T3 action, without the influence of neoplastic transformation or artificial TR over-expression. Furthermore, our data describe novel T3 responsive genes and provide insight into the role of T3 in important processes such as cholesterol metabolism, bile acid secretion, oncogenesis, among others, that can be tested in future experiments in vivo.