Xiaoxue Li

Related publications (4)

Autophagy as a Gatekeeper of Intestinal Homeostasis

Bruno Lemaitre, Xiaoxue Li

The control of gut homeostasis by autophagy in the context of host-microbiota relationship remains poorly understood. In this issue of Developmental Cell, Nagai et al. (2021) show that autophagy plays a crucial role in enterocytes to prevent the mis-regulation of the Hippo-Yorkie pathway by the microbiota.

CELL PRESS2021

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Animals require complex metabolic and physiological adaptations to maintain the function of vital organs in response to environmental stresses and infection. Here, we found that infection or injury in Drosophila induced the excretion of hemolymphatic lipids by Malpighian tubules, the insect kidney. This lipid purge was mediated by a stress-induced lipid-binding protein, Materazzi, which was enriched in Malpighian tubules. Flies lacking materazzi had higher hemolymph concentrations of reactive oxygen species (ROS) and increased lipid peroxidation. These flies also displayed Malpighian tubule dysfunction and were susceptible to infections and environmental stress. Feeding flies with antioxidants rescued the materazzi phenotype, indicating that the main role of Materazzi is to protect the organism from damage caused by stress-induced ROS. Our findings suggest that purging hemolymphatic lipids presents a physiological adaptation to protect host tissues from excessive ROS during immune and stress responses, a process that is likely to apply to other organisms.

2020

Transforming Growth Factor beta/Activin signaling in neurons increases susceptibility to starvation

Wen Bin Chng, Bruno Lemaitre, Xiaoxue Li

Animals rely on complex signaling network to mobilize its energy stores during starvation. We have previously shown that the sugar-responsive TGF beta/Activin pathway, activated through the TGF beta ligand Dawdle, plays a central role in shaping the post-prandial digestive competence in the Drosophila midgut. Nevertheless, little is known about the TGF beta/Activin signaling in sugar metabolism beyond the midgut. Here, we address the importance of Dawdle (Daw) after carbohydrate ingestion. We found that Daw expression is coupled to dietary glucose through the evolutionarily conserved Mio-Mlx transcriptional complex. In addition, Daw activates the TGF beta/Activin signaling in neuronal populations to regulate triglyceride and glycogen catabolism and energy homeostasis. Loss of those neurons depleted metabolic reserves and rendered flies susceptible to starvation.

2017

Remote Control of Intestinal Stem Cell Activity by Haemocytes in Drosophila

Jean Philippe Boquete, Sveta Chakrabarti, Esther Jeanne Collas, Jan Paul Dudzic, Bruno Lemaitre, Xiaoxue Li

The JAK/STAT pathway is a key signaling pathway in the regulation of development and immunity in metazoans. In contrast to the multiple combinatorial JAK/STAT pathways in mammals, only one canonical JAK/STAT pathway exists in Drosophila. It is activated by three secreted proteins of the Unpaired family (Upd): Upd1, Upd2 and Upd3. Although many studies have established a link between JAK/STAT activation and tissue damage, the mode of activation and the precise function of this pathway in the Drosophila systemic immune response remain unclear. In this study, we used mutations in upd2 and upd3 to investigate the role of the JAK/STAT pathway in the systemic immune response. Our study shows that haemocytes express the three upd genes and that injury markedly induces the expression of upd3 by the JNK pathway in haemocytes, which in turn activates the JAK/STAT pathway in the fat body and the gut. Surprisingly, release of Upd3 from haemocytes upon injury can remotely stimulate stem cell proliferation and the expression of Drosomycin-like genes in the intestine. Our results also suggest that a certain level of intestinal epithelium renewal is required for optimal survival to septic injury. While haemocyte-derived Upd promotes intestinal stem cell activation and survival upon septic injury, haemocytes are dispensable for epithelium renewal upon oral bacterial infection. Our study also indicates that intestinal epithelium renewal is sensitive to insults from both the lumen and the haemocoel. It also reveals that release of Upds by haemocytes coordinates the wound-healing program in multiple tissues, including the gut, an organ whose integrity is critical to fly survival.

Public Library of Science2016