Final Report Summary - SHIGELLA INDUCED EMT (Diversion of adherens junctions by bacterial type III effectors during Shigella invasion of polarized intestinal epithelial cells)
Shigella flexneri is a gram-negative pathogenic bacterium that cause devastating diarrhea upon ingestion. The type III secretion system (T3SS) encoded on a large plasmid is a key virulence factor of Shigella flexneri. After epithelial contact, the T3SS induces complex signaling pathways leading to localized membrane ruffling and subsequent bacterial invasion in the cells. The T3SS determines the interactions of the bacteria with intestinal cells by translocating effector proteins into the target cells subverting host cell signal transduction pathways. Shigella invasion is determined by the concerted action of T3SS effectors that reorganize the actin cytoskeleton through the targeting of RhoGTPases and tyrosine kinase signaling. Interestingly, adherens junctions (AJs) are regulated by Rho GTPases and tyrosine kinase. The diversion of RhoGTPases and tyrosine signaling by Shigella effectors regulates the adherens junctions leading to the activation of an Epithelial-to-Mesenchymal-like transition pathway to induce invasion of polarized intestinal cells.
We believe that the regulation of such processes controlling adherens junctions are diverted by Shigella type III effectors during invasion of polarized cells. Cell-cell adhesion is mediated by cadherins, a superfamilly of transmembrane cell-cell adhesion receptors. The goal of this proposal is to characterize the role of the RhoGTPases activation to identify key mechanistic links with tyrosine kinase signaling that regulate intercellular junctions during Shigella invasion of polarized cells.
We have shown so far that invasion of polarized epithelial by Shigella induces an increase in tyrosine phosphorylation. Detergent fractionation to characterize association of proteins with the cytoskeleton upon invasion showed that cortactin was tyrosyl-phosphorylated upon Shigella invasion in polarized epithelial cells. We analyzed cytoskeletal reorganization during Shigella invasion of polarized cells by fluorescence microscopy. We observed that strikingly, actin foci formation at the apical surface of polarized cells occurred almost exclusively at adherens junctions.
Shigella is known to cause bacillary dysentery that is endemic worldwide but especially widespread in young children of the developing world. Shigella infection alone can result in 150 million cases annually and drug resistance is becoming prevalent which stress the need of a better understanding of the mechanisms of infection in order to effectively fight the disease. In the same time, Shigella model of infection can be used as a powerful tool to investigate different pathway like EMT a process associated with normal development, wound healing but also cancer progression and metastasis. The fact that, in order to successfully invade polarized cells, Shigella need the simultaneous activation of Rac1 and RhoA will help us shed some light on the crosstalk between GTPases as Rho and Rac are often antagonistic in their effects.
Infectious diseases and cancer are very different but devastating diseases even if they don’t affect the same part of the word equally. It would be important for the scientific excellence of the EU to investigate innovative approach in order to fight these diseases. The study of Shigella Flexneri mechanism of infection showed by its complexity and is mimicking of cellular transduction pathway of the host cell that we need to develop approaches allowing us to integrate different way of apprehending diseases.
We believe that the regulation of such processes controlling adherens junctions are diverted by Shigella type III effectors during invasion of polarized cells. Cell-cell adhesion is mediated by cadherins, a superfamilly of transmembrane cell-cell adhesion receptors. The goal of this proposal is to characterize the role of the RhoGTPases activation to identify key mechanistic links with tyrosine kinase signaling that regulate intercellular junctions during Shigella invasion of polarized cells.
We have shown so far that invasion of polarized epithelial by Shigella induces an increase in tyrosine phosphorylation. Detergent fractionation to characterize association of proteins with the cytoskeleton upon invasion showed that cortactin was tyrosyl-phosphorylated upon Shigella invasion in polarized epithelial cells. We analyzed cytoskeletal reorganization during Shigella invasion of polarized cells by fluorescence microscopy. We observed that strikingly, actin foci formation at the apical surface of polarized cells occurred almost exclusively at adherens junctions.
Shigella is known to cause bacillary dysentery that is endemic worldwide but especially widespread in young children of the developing world. Shigella infection alone can result in 150 million cases annually and drug resistance is becoming prevalent which stress the need of a better understanding of the mechanisms of infection in order to effectively fight the disease. In the same time, Shigella model of infection can be used as a powerful tool to investigate different pathway like EMT a process associated with normal development, wound healing but also cancer progression and metastasis. The fact that, in order to successfully invade polarized cells, Shigella need the simultaneous activation of Rac1 and RhoA will help us shed some light on the crosstalk between GTPases as Rho and Rac are often antagonistic in their effects.
Infectious diseases and cancer are very different but devastating diseases even if they don’t affect the same part of the word equally. It would be important for the scientific excellence of the EU to investigate innovative approach in order to fight these diseases. The study of Shigella Flexneri mechanism of infection showed by its complexity and is mimicking of cellular transduction pathway of the host cell that we need to develop approaches allowing us to integrate different way of apprehending diseases.