
<ArticleTitle><prot><prot>Interleukin-2</prot> receptor beta</prot> subunit-dependent and -independent regulation of intestinal epithelial tight junctions.</ArticleTitle>
<AbstractText>Interleukin (IL)-15 is able to regulate tight junction formation in intestinal epithelial cells. However, the mechanisms that regulate the intestinal barrier function in response to <prot>IL-15</prot> and the involved subunits of the <prot>IL-15 ligand-receptor</prot> system are unknown. We determined the <prot>IL-2Rbeta</prot> subunit and IL-15-dependent regulation of tight junction-associated proteins in the human intestinal epithelial cell line T-84. The <prot>IL-2Rbeta</prot> subunit was expressed and induced signal transduction in caveolin enriched rafts in intestinal epithelial cells. IL-15-mediated tightening of intestinal epithelial monolayers correlated with the enhanced recruitment of tight junction proteins into Triton X-100-insoluble protein fractions. IL-15-mediated up-regulation of ZO-1 and ZO-2 expression was independent of the <prot>IL-2Rbeta</prot> subunit, whereas the phosphorylation of <prot>occludin</prot> and enhanced membrane association of <prot>claudin-1</prot> and <prot>claudin-2</prot> by <prot>IL-15</prot> required the presence of the <prot>IL-2Rbeta</prot> subunit. Recruitment of <prot>claudin</prot>s and hyperphosphorylated <prot>occludin</prot> into tight junctions resulted in a more marked induction of tight junction formation in intestinal epithelial cells than the up-regulation of <prot>ZO-1</prot> and <prot>ZO-2</prot> by itself. The regulation of the intestinal epithelial barrier function by <prot>IL-15</prot> involves IL-2Rbeta-dependent and -independent signaling pathways leading to the recruitment of <prot>claudin</prot>s, hyperphosphorylated <prot>occludin</prot>, <prot>ZO-1</prot>, and <prot>ZO-2</prot> into the tight junctional protein complex.</AbstractText>
