Nonautonomous regulation of Drosophila midgut stem cell proliferation by the insulin-signaling pathway.

Drosophila adult midgut intestinal stem cells (ISCs) maintain tissue homeostasis by producing progeny that replace dying enterocytes and enteroendocrine cells. ISCs adjust their rates of proliferation in response to enterocyte turnover through a positive feedback loop initiated by secreted enterocyte-derived ligands. However, less is known about whether ISC proliferation is affected by growth of the progeny as they differentiate.

Age-related changes in Drosophila midgut are associated with PVF2, a PDGF/VEGF-like growth factor.

Age-associated changes in stem cell populations have been implicated in age-related diseases, including cancer. However, little is known about the underlying molecular mechanisms that link aging to the modulation of adult stem cell populations. Drosophila midgut is an excellent model system for the study of stem cell renewal and aging.

The caudal homeodomain protein activates Drosophila E2F gene expression.

The Drosophila caudal homeobox gene is required for definition of the anteroposterior axis and for gut development, and CDX1 and CDX2, human homologs, play crucial roles in the regulation of cell proliferation and differentiation in the intestine. Most studies have indicated tumor suppressor functions of Cdx2, with inhibition of proliferation, while the effects of Cdx1 are more controversial. The influence of Drosophila Caudal on cell proliferation is unknown.