Project Details
Projekt
Functional characterization of CD97 in intestinal epithelial cells
Subject Area
General and Visceral Surgery
Gastroenterology
Gastroenterology
Term
from 2009 to 2020
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 147293537
CD97, an adhesion-GPCR, is expressed in epithelial adherens junctions of the normal human intestine. In the first proposal we evaluated the function of CD97 within these cells using Cd97-transgenic mice. In the present proposal two new, clinically relevant aspects will be examined: A In intestinal biopsies of Tg(villin-CD97) mice the stimulated chloride secretion increased whereas in stable CD97 siRNA colorectal cell clones chloride secretion decreased. These and other data suggest that CD97 regulates the cystic fibrosis transmembrane conductance regulator (CFTR). Mutations in the CFTR gene are responsible for cystic fibrosis, the most frequent monogenetic disease which reduces life span to 40 years only. The aim of the present proposal is to verify the hypothesis -CD97 regulates the CFTR- at various levels, including expression (transcription, translation, transport, localization, stability) and function (folding, opening/closure) of the CFTR. We established the 3D culture of murine intestinal stem cells for its use in forskolin-induced (FIS) and radiation-induced swelling (RIS). Thus, in organoids of new double Cd97/Cftr-transgenic mice we will verify, beside by classical experiments with these animals, whether CD97 regulates the CFTR. A strategy for the electrophysiological analysis of a direct interaction of CD97 with the wildtype- and mutated CFTR are two electrode voltage clamp and patch clamp-experiments with Xenopus laevis oocytes which coexpress both receptors. We will clarify whether CD97 regulates and rescues the mutated CFTR and whether an activation or increase of the CFTR is involved in the development of a radiation-induced gastrointestinal syndrome (RIGS). Our results may open new therapeutic approaches to regulate the expression and/or function of the mutated CFTR by CD97 in patients with cystic fibrosis. B In mammals intestinal growth after birth proceeds in two phases which are caused probably by different molecular pattern or regulatory mechanisms. Cylindrical intestinal growth, that is an increase in length and diameter with normal microscopic anatomy, dominates after birth before weaning. Interestingly, Tg(villin-CD97) mice develop a megaintestine with normal microscopic anatomy after birth. Thus, these mice are a unique model to identify the unknown molecular pattern of cylindrical intestinal growth. We will verify the following hypothesis: The interaction of CD97 with the CFTR is involved in the regulation of intestinal growth, CD97 regulates crypt fissioning in the small intestine after birth and CD97 regulates a receptor for a timely-restricted trophic (milk)-factor in the intestinal epithelium. With these results we could also increase our knowledge on the missing induction of a favored cylindrical intestinal growth pattern during therapy of patients with short bowel syndrome.
DFG Programme
Research Grants
