Rat lactase-phlorizin hydrolase human growth hormone transgene is expressed on small intestinal villi in transgenic mice

Background & Aims: Lactase-phlorizin hydrolase (LPH) is an absorptive enterocyte-specific gene that is expressed in a well-characterized pattern along the crypt-villus (vertical), proximal-distal (horizontal), and developmental (temporal) gradients. The aim of this study was to characterize the capacity of regulatory elements within the rat LPH gene to direct appropriate cell lineage and topographical patterns of expression in vivo in transgenic mice. Methods: Transgenic mouse lines were established using a construction containing bases -2038 to +15 of the rat LPH gene fused to a human growth hormone reporter gene. Results: In one line, the transgene was expressed only in small intestine and was localized to absorptive enterocytes on villi. The transgene was not expressed in goblet or enteroendocrine cells or in crypts. Transgene expression along horizontal and developmental gradients was different from that of the native mouse LPH gene. Conclusions: The results suggest that the region from -2038 to +15 of the rat LPH gene contains regulatory elements that direct correct tissue, cell, and vertical expression but may not contain all the elements necessary for appropriate horizontal and temporal control. This investigation provides further insight into the complexities of the molecular control of intestinal gene expression.