A subset of neurons controls the permeability of the peritrophic matrix and midgut structure in Drosophila adults

Abstract

The metazoan gut performs multiple physiological functions, including digestion and absorption of nutrients, and also serves as a physical and chemical barrier against ingested pathogens and abrasive particles. Maintenance of these functions and structures is partly controlled by the nervous system, yet the precise roles and mechanisms of the neural control of gut integrity remain to be clarified in Drosophila. Here, we screened for GAL4 enhancer-trap strains and labeled a specific subsets of neurons, using Kir2.1 to inhibit their activity. We identified an NP3253 line that is susceptible to oral infection by Gram-negative bacteria. The subset of neurons driven by the NP3253 line includes some of the enteric neurons innervating the anterior midgut, and these flies have a disorganized proventricular structure with high permeability of the peritrophic matrix and epithelial barrier. The findings of the present study indicate that neural control is crucial for maintaining the barrier function of the gut, and provide a route for genetic dissection of the complex brain-gut axis in adults of the model organism Drosophila.

Anatomy and Physiology of the Digestive Tract of Drosophila melanogaster

“…While the foregut and hindgut are lined by an impermeable cuticle, a more permeable structure — the peritrophic matrix — protects the midgut. The peritrophic matrix is composed of chitin fibrils and chitin-binding proteins that are assembled in the proventriculus, remodeled along the midgut and eventually degraded at the mid-hindgut junction ( Kenmoku et al 2016 ). The presence of a peritrophic matrix and epithelial tight septate junctions explains why only rare pathogens are capable of breaching the gut and penetrate the hemolymph compartment ( Nehme et al 2007 ; Kuraishi et al 2011 ; Bonnay et al 2013 ; Shibata et al 2015 ).…”

Drosophila Histone Demethylase KDM5 Regulates Social Behavior through Immune Control and Gut Microbiota Maintenance

“…Feeding Assay with FITC-Labeled Beads 3-7 days old female flies were starved for 3 hr at 25 C before feeding FITC-labeled beads (30 nm diameter, Polysciences, Warrington, PA, USA) to monitor the permeability of the anterior midgut, as described previously (Kenmoku et al, 2016). The guts were dissected after feeding for 15-30 min, and then put guts on the slides and captured image using an Olympus conventional fluorescence microscope.…”

“…Whole guts were fixed in 13PBS with 4% paraformaldehyde for 30 min at 25 C. Samples were washed in PBS with 0.1% Triton X-100 (PBST) three times, 10 min each. Then the tissues were prewashed in 5% BSA in PBST for at least 30 min at 25 C. For anti-PH3 antibody staining, the samples were fixed with 3.7% formaldehyde in PBS, permeabilized with 99.5% pre-chilled ethanol at -30 C for 5 min per the previous published method (Kenmoku et al, 2016). Samples were incubated with anti-Relish (RayBiotech) or anti-PH3 (Cell signaling) at 1:100 dilution overnight.…”

Organ-to-Organ Communication: A Drosophila Gastrointestinal Tract Perspective

“…Growing evidence gleaned by Olds WH and Xu T has suggested that the loss of PPK1 in posterior enteric neurons reduces food intake levels through mechanosensory ion channels (Olds and Xu, 2014). According to Kenmoku et al, the maintenance of barrier function is causally linked to a specific subset of enteric neurons innervating the anterior midgut (Kenmoku et al, 2016). The peritrophic matrix and epithelial barrier of flies with loss of activity of these enteric neurons display high permeability (Kenmoku et al, 2016).…”

“…According to Kenmoku et al, the maintenance of barrier function is causally linked to a specific subset of enteric neurons innervating the anterior midgut (Kenmoku et al, 2016). The peritrophic matrix and epithelial barrier of flies with loss of activity of these enteric neurons display high permeability (Kenmoku et al, 2016). Taken together, these findings suggest that this neuron-gut communication strategy has far-reaching effects on the regulation of intestinal regeneration and physiology.…”