Project description:Glucocorticoids are primary stress hormones and their synthetic derivatives are widely used clinically. The therapeutic efficacy of these steroids is limited by severe side effects and glucocorticoid resistance. Multiple glucocorticoid receptor (GR) isoforms are produced by alternative translation initiation; however, the role individual isoforms play in controlling tissue-specific responses to glucocorticoids in vivo is unknown. We have generated knockin mice that exclusively express the most active receptor isoform, GR-C3. The GR-C3 knockin mice die at birth due to respiratory distress but can be completely rescued by antenatal glucocorticoid administration. Rescued GR-C3 mice exhibited alterations in circadian rhythm in a sexually dimorphic manner and in sensitivity to lipopolysaccharide (LPS)-induced endotoxemia. To evaluate the ability of glucocorticoids to protect against LPS-induced inflammation, we measured gene expression in spleens from WT and rescued GR-C3 knockin mice that had been treated with vehicle or LPS for 3 and 24 hours. The GR-C3 isoform was found to be deficient in its ability to repress a large cohort of immune and inflammatory genes.
Project description:We developed a novel, rapidly-progressing, severe murine model of C3G by replacing the mouse C3 gene with the human C3 homologue using Velocigene® technology. We conducted functional, histological, molecular and pharmacologic assays to characterize the presentation of renal disease and useful pharmacologic interventions in the humanized C3 (C3hu/hu) mice.
Project description:In our study, we investigated the effect of Vasoactive intestinal peptide (VIP) on murine intestinal stem cell (ISC) activity and differentiation in homeostatic conditions and following irradiation-induced injury. We utilized a model of murine intestinal organoids and observed that VIP promotes epithelial differentiation towards a secretory phenotype predominantly via the p38 MAPK pathway. Moreover, VIP prominently modulates epithelial proliferation as well as the number and proliferative activity of Lgr5-EGFP+ ISC under homeostatic conditions. Further analysis revealed that in vitro acute irradiation injury renders Lgr5-EGFP+ ISC even more susceptible to modulations by VIP, which results in the strong promotion of epithelial regeneration by VIP. Finally, these effects by VIP translate into an in vivo model of abdominal irradiation, where VIP was shown to prominently mitigate radiation-induced injury. Taken together, our findings indicate a prominent role of VIP in modulating ISC behavior in intestinal homeostasis and its potential to promote intestinal regeneration following acute irradiation injury.
Project description:Glucocorticoids are primary stress hormones and their synthetic derivatives are widely used clinically. The therapeutic efficacy of these steroids is limited by severe side effects and glucocorticoid resistance. Multiple glucocorticoid receptor (GR) isoforms are produced by alternative translation initiation; however, the role individual isoforms play in controlling tissue-specific responses to glucocorticoids in vivo is unknown. We have generated knockin mice that exclusively express the most active receptor isoform, GR-C3. The GR-C3 knockin mice die at birth due to respiratory distress but can be completely rescued by antenatal glucocorticoid administration. To evaluate the GR-C3 transcriptome, we prepared mouse embryonic fibroblasts (MEFs) from E12.5 wild-type (WT) and GR-C3 knockin embryos and treated the cells with vehicle or the synthetic glucocorticoid Dexamethasone (Dex) for 6 hours. The GR-C3 isoform was found to have a markedly different gene-regulatory profile than GR in WT MEFs.
Project description:The complement component C3 is a fundamental plasma protein for host defense, produced largely by the liver. However, recent work has demonstrated the critical importance of tissue-specific C3 expression in cell survival. Here we analyzed the effects of local versus peripheral sources of C3 expression in a model of bacterial pneumonia. While mice with global C3 deficiency had severe pneumonia-induced lung injury, those deficient in liver-deficient C3 remain protected, comparable to wildtype mice. Human lung transcriptome analysis showed that secretory epithelial cells, such as club cells, are a major source of C3. Mice with a tamoxifen-induced C3 gene ablation from club cells in the lung had worse pulmonary injury compared to similarly treated controls, despite maintaining normal circulating C3 levels. Finally, in human cellular and mouse pneumonia models, we show that C3 reduces epithelial cell death mediated through the alternative pathway component Factor B, rather than the C3aR. Thus, our findings suggest that a locally-derived C3-Factor B pathway protects the lung mucosal barrier.
Project description:Toxoplasma gondii is a ubiquitous parasite of warm-blooded animals. Parasites can switch into the chronic infection following exposure to stress. PKA C3 is a protein kinase involved in the differentiation process. Here, we determine the phosphoproteome of parasites conditionally depleted of PKA C3.