Differential effects of commensal bacteria on progenitor cell adhesion, division symmetry and tumorigenesis in the intestine.

Microbial factors influence homeostatic and oncogenic growth in the intestinal epithelium. However, we know little about immediate effects of commensal bacteria on stem cell division programs. In this study, we examined the effects of commensal species on homeostatic and tumorigenic stem cell proliferation in the female intestine. We identified as a potent stimulator of stem cell divisions. In a wild-type midgut, activates growth regulatory pathways that drive stem cell divisions. In a Notch-deficient background, -mediated proliferation causes rapid expansion of mutant progenitors, leading to accumulation of large, multi-layered tumors throughout the midgut. Mechanistically, we showed that disrupts expression and subcellular distribution of progenitor cell integrins, supporting symmetric divisions that expand intestinal stem cell populations. Collectively, our data emphasize the impact of commensal microbes on division and maintenance of the intestinal progenitor compartment.