Changes in Jak3 Expression during the Differentiation of Intestinal epithelial cells*

Abstract

Changes in genetic expression play a central role during the differentiation of intestinal epithelial cells (IEC). Previously we have reported that Jak3 plays an essential role during mucosal wound repair an important ramification for patients with ulcerative colitis and Crohn's disease. Here we determine the physiological significance of Jak‐3 expression during enterocytic differentiation. Jak‐3 expression was determined in sub‐confluent, confluent, 2‐ and 3‐week post‐confluent HT‐29 Cl‐19a cells through western analysis using Jak‐3 antibody. Reduced Jak‐3 expression was observed in sub‐confluent cells and the expression was increased with differentiation. Interestingly an additional lower mol. wt. Jak3 was detected only at 2 weeks of post confluent cells but not at 3 weeks post confluence indicating the possibility of a non phosphorylated form. To determine the effect of Jak‐3 on the differentiation of HT‐29, Jak‐3 was over expressed in HT‐29 cells and its differentiation was monitored using the differentiation marker sucrose isomaltase. Results show that over expression of Jak‐3 potentiate the differentiation of IEC. Densitometric analysis of the ratio of Jak3 to â‐actin expression shows a 1.5 fold increase in Jak3 expression. Taken together these results indicate that Jak3 expression regulate the differentiation of IEC. *This work was supported a grant from CCFA (to NK)