LI-cadherin gene expression during mouse intestinal development.

LI-cadherin (Liver-Intestine cadherin) is a member of a subclass (7-D cadherins) within the cadherin superfamily. Although its cellular function as a cell-cell adhesion molecule has been demonstrated in cell culture studies, its physiological function still needs to be explored in the intact organism. After isolating the cDNA for mouse LI-cadherin, we generated specific antibodies against the overexpressed protein and studied its expression pattern in adult mouse tissues and mouse embryos. The mouse LI-cadherin sequence is 91% identical to the sequence of rat LI-cadherin and exhibits the same structural features described for rat LI-cadherin. In mouse adult tissue, LI-cadherin is expressed in the intestine and in small amounts in the spleen. In contrast to rat, Mouse LI-cadherin was not expressed in liver. During mouse embryogenesis, LI-cadherin expression begins at embryonic day 12.5. With the exception of transient expression in the urogenital sinus and the common bile duct on day 13.5, LI-cadherin was found exclusively in the intestinal epithelium. Its expression coincides with the formation of intestinal villi, a developmental stage that includes major tissue remodeling, growth, and differentiation. LI-cadherin is expressed along the entire anterior-posterior axis of the developing intestine as well as along the entire villus axis once villi begin to form. LI-cadherin occupies all cell surfaces of the deeper layers of the epithelium, distributing to basolateral surfaces only in the cells of the outer epithelial layer. LI-cadherin was found to be always co-expressed with E-cadherin.