Thyroid and Glucocorticoid Hormones Induce Expression of Lactase-Phlorizin Hydrolase Gene in CDX-2/HNF-1α Co-Transfected IEC-6 Cells

Thyroid and glucocorticoid hormones and several transcriptional factors such as caudal type homeobox (CDX)-2 and hepatocyte nuclear factor (HNF)-1 alpha are important for the differentiation of small intestinal absorptive cells and the consequent expression of genes related to the digestion/absorption of carbohydrates. In this study, we investigated whether thyroid and glucocorticoid hormones enhanced the expression of lactase-phlorizin hydrolase (LPH) gene, an intestine-specific gene that encodes an enzyme for lactose digestion, in small intestinal stem-like IEC-6 cells co-transfected with CDX-2 and HNF-1 alpha using a retrovirus system. Changes in expression of intestine-specific genes caused by treatment with thyroid and/or glucocorticoid hormones were monitored in empty vector-transfected cells and in CDX-2/HNF-1 alpha co-transfected cells by qRT-PCR. Stable co-transfection with CDX-2 and HNF-1 alpha evoked the expression of the LPH gene in IBC-6 cells. Furthermore, treatment with a thyroid hormone, triiodothyronine, and a glucocorticoid receptor agonist, dexamethasone, significantly enhanced expression of the LPH, CDX-2 and HNF-1 alpha genes in CDX-2/HNF-1 alpha co-transfected IEC-6 cells. These results suggest that thyroid and glucocorticoid hormones synergistically enhance expression of the LPH gene in CDX-2/HNF-1 alpha co-transfected IEC-6 cells.