Overexpression of GDE1 decreases glycerophosphoinositol in intestinal epithelial cells in vivo.

Glycerophosphoinositol (GPI), a product of phospholipases acting on membrane phosphoinositides, is increasingly being recognized as an important bioactive molecule. However, its cellular functions in vivo remain unexplored. Recently, several mammalian glycerophosphodiesterases (GDEs) have shown to be involved in the catabolism of GPI, possibly regulating its intracellular levels. Given the growing interest in biological significance of GPI in intestinal epithelial cells, this study focused on screening a GDE involved in intracellular GPI metabolism. Our results showed that GDE1 mRNA was highly expressed in intestinal epithelial cells and that its overexpression decreased intracellular GPI in cultured cells. We then created transgenic mice with GDE1 overexpression specifically in intestinal epithelial cells. These mice showed that GDE1 protein is localized in epithelial cells and that GPI levels are downregulated in the colon epithelial layers. This study provides a novel animal model for exploring GPI functions in vivo.