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The aryl hydrocarbon receptor (AHR) plays important roles in intestinal homeostasis, limiting tumour growth and promoting differentiation in the intestinal epithelium. Spineless, theDrosophilahomolog of AHR, has only been studied in the context of development but not in the adult intestine. Here, we show thatspinelessis upregulated in the adult intestinal epithelium after infection withPseudomonas entomophila(P.e.). Spineless knockdown increased stem cell proliferation following infection-induced injury. Spineless overexpression limited intestinal stem cell proliferation and reduced survival after infection. In two tumour models, using eitherNotchRNAi or constitutively active Yorkie, Spineless suppressed tumour growth and doubled the lifespan of tumour-bearing flies. At the transcriptional level it reversed the gene expression changes induced in Yorkie tumours, counteracting cell proliferation and altered metabolism. These findings demonstrate a new role for Spineless in the adultDrosophilamidgut and highlight the evolutionarily conserved functions of AHR/Spineless in the control of proliferation and differentiation of the intestinal epithelium.

International audience; Microsporidia are located at the base of the fungal evolutionary tree. They are obligate intracellular parasites and harness host metabolism to fuel their growth and proliferation. However, how the infestation of cells affects the whole organism and how the organism contributes to parasite proliferation remain poorly understood. Here, we have developed a Tubulinosema ratisbonensis systemic infection model in the genetically amenable Drosophila melanogaster host, in which parasite spores obtained in a mammalian cell culture infection system are injected into adult flies. The parasites proliferate within flies and ultimately kill their hosts. As commonly observed for microsporidia infecting insects, T. ratisbonensis preferentially grows in the fat body and ultimately depletes the host metabolic stores. We find that supplementing the fly diet with yeast does not benefit the host but the parasite, which increases its proliferation. Unexpectedly, fatty acids and not carbohydrates or amino acids are the critical components responsible for this phenomenon. Our genetic dissection of host lipid metabolism identifies a crucial compound hijacked by T. ratisbonensis: phosphatidic acid. We propose that phosphatidic acid is a limiting precursor for the synthesis of the parasite membranes and, hence, of its proliferation.

Fipronil is a phenyl pyrazole molecule widely used across the world as both insecticide and veterinary drug. The main goal of this work was to synthesize a fluorescently labeled fipronil derivative for cellular imaging without affecting its intrinsic properties. We selected fluorescein as fluorescent probe and we investigated different strategies for stable chemical ligation between both entities, such as thiourea and direct peptide bond. While thiourea bond displayed low stability, direct peptide bond was difficult to achieve due to problems of steric hindrance. The best result was obtained by conjugation using click chemistry, which allowed to obtain fipronil stably labeled with the fluorescent probe. journal article 2018 Jun 19 2018 06 19 imported In Press, Corrected Proof

We present the draft genome sequence of Tubulinosema ratisbonensis, a microsporidium species infecting Drosophila melanogaster. A total of 3,013 protein-encoding genes and an array of transposable elements were identified. This work represents a necessary step to develop a novel model of host-parasite relationships using the highly tractable genetic model D. melanogaster.

International audience; When Drosophila melanogaster feeds on Pseudomonas aeruginosa, some bacteria cross the intestinal barrier and eventually proliferate in the hemocoel. This process is limited by hemocytes through phagocytosis. P. aeruginosa requires the quorum-sensing regulator RhlR to elude the cellular immune response of the fly. RhlI synthesizes the autoinducer signal that activates RhlR. Here, we show that rhlI mutants are unexpectedly more virulent than rhlR mutants, both in fly and in nematode intestinal infection models, suggesting that RhlR has RhlI-independent functions. We also report that RhlR protects P. aeruginosa from opsonization mediated by the Drosophila thioester-containing protein 4 (Tep4). RhlR mutant bacteria show higher levels of Tep4-mediated opsonization, as compared to rhlI mutants, which prevents lethal bacteremia in the Drosophila hemocoel. In contrast, in a septic model of infection, in which bacteria are introduced directly into the hemocoel, Tep4 mutant flies are more resistant to wild-type P. aeruginosa, but not to the rhlR mutant. Thus, depending on the infection route, the Tep4 opsonin can either be protective or detrimental to host defense.

WhenDrosophilaflies feed onPseudomonas aeruginosastrain PA14, some bacteria cross the intestinal barrier and start proliferating inside the hemocoel. This process is limited by hemocytes through phagocytosis. We have previously shown that the PA14 quorum-sensing regulator RhlR is required for these bacteria to elude the cellular immune response. RhlI synthesizes the auto-inducer signal that activates RhlR. Here, we compare the null mutant phenotypes ofrhlRandrhlIin a variety of infection assays inDrosophilaand in the nematodeCaenorhabditis elegans. Surprisingly, inDrosophila, unlikeΔrhlRmutants,ΔrhlImutants are only modestly attenuated for virulence and are poorly phagocytosed and opsonized in a Thioester-containing Protein4-dependent manner. Likewise, ΔrhlIbut not ΔrhlRmutants colonize the digestive tract ofC. elegansand kill it as efficiently as wild-type PA14. Thus, RhlR has an RhlI-independent function in eluding detection or counter-acting the action of the immune system. In contrast to the intestinal infection model,Tep4mutant flies are more resistant to PA14 in a septic injury model, which also depends onrhlR. Thus, the Tep4 putative opsonin can either be protective or detrimental to host defense depending on the infection route.

Microsporidia are located at the base of the fungal evolutionary tree. They are obligate intracellular parasites and harness host metabolism to fuel their growth and proliferation. However, how the infestation of cells affects the whole organism and how the organism contributes to parasite proliferation remain poorly understood. Here, we have developed a Tubulinosema ratisbonensis systemic infection model in the genetically amenable Drosophila melanogaster host, in which parasite spores obtained in a mammalian cell culture infection system are injected into adult flies. The parasites proliferate within flies and ultimately kill their hosts. As commonly observed for microsporidia infecting insects, T. ratisbonensis preferentially grows in the fat body and ultimately depletes the host metabolic stores. We find that supplementing the fly diet with yeast does not benefit the host but the parasite, which increases its proliferation. Unexpectedly, fatty acids and not carbohydrates or amino acids are the critical components responsible for this phenomenon. Our genetic dissection of host lipid metabolism identifies a crucial compound hijacked by T. ratisbonensis: phosphatidic acid. We propose that phosphatidic acid is a limiting precursor for the synthesis of the parasite membranes and, hence, of its proliferation.

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