In the small intestine, the progeny of stem cells migrate in precise patterns. Absorptive, enteroendocrine, and goblet cells migrate toward the villus while Paneth cells occupy the bottom of the crypts. We show here that beta-catenin and TCF inversely control the expression of the EphB2/EphB3 receptors and their ligand ephrin-B1 in colorectal cancer and along the crypt-villus axis. Disruption of EphB2 and EphB3 genes reveals that their gene products restrict cell intermingling and allocate cell populations within the intestinal epithelium. In EphB2/EphB3 null mice, the proliferative and differentiated populations intermingle. In adult EphB3(-/-) mice, Paneth cells do not follow their downward migratory path, but scatter along crypt and villus. We conclude that in the intestinal epithelium beta-catenin and TCF couple proliferation and differentiation to the sorting of cell populations through the EphB/ephrin-B system.

Pseudomonas aeruginosa is a Gram-negative bacterium that is notorious for infections in the airway of cystic fibrosis (CF) subjects. Often, these infections become chronic, leading to higher morbidity and mortality rates. Bacterial quorum sensing (QS) coordinates the expression of virulence factors and the formation of biofilms at a population level. QS has become the focus of attention for development of alternatives to antimicrobials targeting P. aeruginosa infections. However, a better understanding of the bacteria-host interaction, and the role of QS in infection, is required. In this study, we set up a new P. aeruginosa infection model, using 2D airway organoids derived from healthy and CF individuals. Using dual RNA-sequencing, we dissected their interaction, focusing on the role of QS. As expected, P. aeruginosa induced epithelial inflammation. However, QS signaling did not affect the epithelial airway cells. The epithelium influenced several infection-related processes of P. aeruginosa, including metabolic changes, induction of type 3 and type 6 secretion systems (T3SS and T6SS), and increased expression of antibiotic resistance genes, including mexXY efflux pump and several porins. Interestingly, the epithelium influenced the regulation by QS of the type 2 (T2SS) and T6SS. Finally, we compared our model with in vivo P. aeruginosa transcriptomic datasets, from samples directly isolated from the airways of CF subjects. This shows that our model recapitulates important aspects of in vivo infection, like enhanced denitrification, betaine/choline metabolism, increased antibiotic resistance, as well as an overall decrease of motility-related genes. This relevant infection model is interesting for future investigations, helping to reduce the burden of P. aeruginosa infections in CF.