Anatomy and Physiology of the Digestive Tract of Drosophila melanogaster

Abstract

The gastrointestinal tract has recently come to the forefront of multiple research fields. It is now recognized as a major source of signals modulating food intake, insulin secretion and energy balance. It is also a key player in immunity and, through its interaction with microbiota, can shape our physiology and behavior in complex and sometimes unexpected ways. The insect intestine had remained, by comparison, relatively unexplored until the identification of adult somatic stem cells in the Drosophila intestine over a decade ago. Since then, a growing scientific community has exploited the genetic amenability of this insect organ in powerful and creative ways. By doing so, we have shed light on a broad range of biological questions revolving around stem cells and their niches, interorgan signaling and immunity. Despite their relatively recent discovery, some of the mechanisms active in the intestine of flies have already been shown to be more widely applicable to other gastrointestinal systems, and may therefore become relevant in the context of human pathologies such as gastrointestinal cancers, aging, or obesity. This review summarizes our current knowledge of both the formation and function of the Drosophila melanogaster digestive tract, with a major focus on its main digestive/absorptive portion: the strikingly adaptable adult midgut.

Polyploidy in the adultDrosophilabrain

“…Polyploidy can confer cell-type and context specific benefits in various tissues. In Drosophila , polyploid intestinal enterocytes 76 , SPGs 19,20 and cells in the wounded epithelium 33,77 undergo endoreduplication and do not undergo cytokinesis to maintain the integrity of the blood brain barrier and the cell-cell junctions in the epithelium respectively. One possibility is that polyploidy in neurons or glia may allow cells to compensate for cell loss while maintaining established cell-cell contacts.…”

An abundant quiescent stem cell population inDrosophilaMalpighian tubules protects principal cells from kidney stones

“…The Drosophila digestive system provides an outstanding model in which to identify novel mechanisms of tissue maintenance by stem cells (reviewed in Losick et al, 2011;Miguel-Aliaga et al, 2018). Highly active midgut intestinal stem cells (ISCs) produce regionally distinctive enterocytes and enteroendocrine cells throughout the midgut via asymmetric Notch signaling (Buchon et al, 2013;Dubreuil, 2004;Filshie et al, 1971;Marianes and Spradling, 2013;McNulty et al, 2001;Mehta et al, 2009;Shanbhag and Tripathi, 2009;Veenstra et al, 2008).…”

Shavenbaby protein isoforms orchestrate the self-renewalversusdifferentiation ofDrosophilaintestinal stem cells

“…The Ecdysone receptor binds to pri cis-regulatory enhancers and trigger pri expression upon elevation of Ecdysone titer (Chanut-Delalande et al, 2014). Although Ecdysone influences intestine stem cells , the role of Ecdysone in midgut homeostasis remains to be fully elucidated (Miguel-Aliaga et al, 2018). We find that disrupting Ecdysone signaling affects the behavior of intestinal stem cells, decreasing proliferation and promoting differentiation, i.e., as observed upon inhibition of Svb processing.…”