|Ph.D Student||Elkouby-Naor Liron|
|Subject||Interactions between Claudin Tight Junction Proteins|
in Various Physiological Systems
|Department||Department of Medicine||Supervisor||Professor Tamar Ben-Yosef|
|Full Thesis text|
The transcellular and the paracellular routes are the pathways through which solutes and water move across epithelial cells and between them, respectively. The major selective barrier of the paracellular pathway is created by tight junctions (TJs). TJs form regions of intimate contact between the plasma membranes of adjacent epithelial cells, thus preventing or reducing paracellular diffusion. The main components of TJ strands are 23 members of the claudin family of proteins. Many tissues including the eye, the kidney and the inner ear express multiple claudins, which interact with each other in both homotypic and heterotypic manners. In this work we used several approaches to explore claudins biology. To study the regulation of Cldn11, a member of the claudin family, at the transcriptional level, we performed detailed analysis of the promoter region. Using the luciferase assay and site directed mutagenesis, we identified the GATA family of transcription factors as regulators of this gene. To study the functional interactions between different claudins we generated a mouse model in which more than one claudin gene is abolished, the claudin11/claudin 14 double deficient mutant mice. These mice exhibit a combination of the phenotypes found in each of the singly deficient mutants, including deafness, neurological deficits and male sterility. Examination of other organs in which both claudins are expressed, including the kidney, revealed no additional abnormalities. To establish a basis for the identification of claudin-related ocular phenotypes, we determined claudin expression profile in the mouse eye. RT-PCR analysis of the mouse eye revealed changes in claudin expression pattern in the adult eye comparing to the embryo (E14). Claudins 1, -2, -3, -4, -5, -7, -10, -11, -12, -13, -19 and -23 are expressed in the adult, while in the embryo, claudins 6, -8 and -16 were also detectable. By immunofluorescence staining we determined the localization of the various claudins in the adult mouse eye. The project described here will lead to a better understanding of the contribution of claudin proteins to various physiological systems and the interactions between them.