Project Details
Projekt
Consequences of desmoglein 2 loss for organization and function of intestinal epithelial junctions
Applicant
Professor Dr. Pavel Strnad
Subject Area
Cell Biology
Term
from 2015 to 2019
Project identifier
Deutsche Forschungsgemeinschaft (DFG) - Project number 273723961
Intestinal epithelia protect the organism against luminal pathogens while enabling selective uptake of nutrients. These dual functions are supported by the apical junctional complex, which is localized at the adluminal plasma membranes of adjacent cells and consists of circumferential tight junction strands (TJs), the adherens junction belt (AJs) and multiple spot-like desmosomal contact sites. While the function of TJs and AJs for intestinal homeostasis has been investigated in detail, much less is known about desmosomes. They are multiprotein complexes with transmembrane cadherins of the desmoglein (Dsg) and desmocollin type at their core that are associated through intracellular plaque proteins to the cytoplasmic keratin intermediate filament cytoskeleton. We recently generated intestine-specific desmoglein 2 gene (DSG2) knockouts to examine desmosomal cadherin-dependent biological functions of intestinal desmosomes. These mice display no obvious clinical phenotype. Yet, the levels of desmosomal, AJ and TJ proteins are significantly altered. Furthermore, the knockout mice are markedly susceptible to chemically-induced colitis as evidenced by increased weight loss, colon shortening, stronger epithelial damage and increased intestinal levels of proinflammatory cytokines. The goal of the project is to examine the consequences of Dsg2 depletion on the organization and function of the apical junctional complex. We propose that compromised function of the apical junctional complex is responsible for the increased susceptibility of DSG2 knockouts to intestinal injury. To pursue our goal and to investigate our hypothesis we will examine our knockout mice and cultured intestinal tumor cells with a stable DSG2 knockdown. First, we will analyze desmosomal composition, ultrastructure and dynamics and desmosome-dependent adhesion. We will perform immunoprecipitation experiments to study how the ablation of Dsg2 affects the interaction of the remaining desmosomal proteins. Secondly, we will investigate the consequences of Dsg2 loss for the function of TJs and AJs. In this context, we will study intestinal barrier integrity and efficiency of resorption and secretion. Thirdly, we will study the effects of Dsg2 depletion on overall intestinal epithelial physiology by examining migration and differentiation of epithelial cells along the crypt-villus axis, by studying mechanical resilience, adhesive properties and susceptibility to apoptosis of intestinal epithelial cells, and by investigating catenin signaling and protection against microbial infections. The project will improve our understanding of the contribution of desmosomal cadherins to desmosomal functions in the context of the apical junctional complex of intestinal epithelia with the long-term goal to elucidate the role of these prominent cell-cell contact sites for the maintenance and control of intestinal epithelial proliferation and differentiation.
DFG Programme
Priority Programmes
