Project description:Inflammatory bowel disease (IBD) is multi-factorial chronic intestinal inflammation driven by pathogenic T cells. The mechanisms underlying colitis pathogenicity and anti-TNF therapy resistance are not fully understood. Here we demonstrate that RORα is highly expressed in active UC patients, particularly in those non-responsive to anti-TNF treatment. Rorα deficient CD4+ T cells could not induce severe gut inflammation in a T cell transfer colitis model. Mechanistically, RORα regulated T cell infiltration in colon by promoting T cell migration and inhibiting T cell apoptosis. Meanwhile, genome-wide occupancy and transcriptome analysis revealed that RORα promoted mTORC1 activation. mTORC1 signaling, also hyperactivated in active UC patients, was necessary for T cell-mediated colitis.
Project description:Inflammatory bowel disease (IBD) is multi-factorial chronic intestinal inflammation driven by pathogenic T cells. The mechanisms underlying colitis pathogenicity and anti-TNF therapy resistance are not fully understood. Here we demonstrate that RORα is highly expressed in active UC patients, particularly in those non-responsive to anti-TNF treatment. Rorα deficient CD4+ T cells could not induce severe gut inflammation in a T cell transfer colitis model. Mechanistically, RORα regulated T cell infiltration in colon by promoting T cell migration and inhibiting T cell apoptosis. Meanwhile, genome-wide occupancy and transcriptome analysis revealed that RORα promoted mTORC1 activation. mTORC1 signaling, also hyperactivated in active UC patients, was necessary for T cell-mediated colitis.
Project description:Inflammatory bowel disease (IBD) is multi-factorial chronic intestinal inflammation driven by pathogenic T cells. The mechanisms underlying colitis pathogenicity and anti-TNF therapy resistance are not fully understood. Here we demonstrate that RORα is highly expressed in active UC patients, particularly in those non-responsive to anti-TNF treatment. Rorα deficient CD4+ T cells could not induce severe gut inflammation in a T cell transfer colitis model. Mechanistically, RORα regulated T cell infiltration in colon by promoting T cell migration and inhibiting T cell apoptosis. Meanwhile, genome-wide occupancy and transcriptome analysis revealed that RORα promoted mTORC1 activation. mTORC1 signaling, also hyperactivated in active UC patients, was necessary for T cell-mediated colitis.
Project description:Cells and organisms adjust their growth based on the availability of cholesterol, which is essential for cellular functions. However, the mechanisms by which cells sense cholesterol levels and translate these into growth signals are not fully understood. We report that cholesterol rapidly activates the master growth-regulatory TOR pathway in Drosophila tissues. We identify the nuclear receptor HR3, an ortholog of mammalian RORα, as an essential factor in cholesterol-induced TOR activation. We demonstrate that HR3 binds cholesterol and promotes TOR pathway activation through a non-genomic mechanism acting upstream of the Rag GTPases. Similarly, we find that RORα is necessary for cholesterol-mediated TOR activation in human cells, suggesting that HR3/RORα represents a conserved mechanism for cholesterol sensing that couples cholesterol availability to TOR-pathway activity. These findings advance our understanding of how cholesterol influences cell growth, with implications for cholesterol-related diseases and cancer. Here, we demonstrate that dietary cholesterol intake leads to rapid and dynamic activation of the TOR pathway in tissues of Drosophila. This response is modulated by the Drosophila RORα ortholog, HR3, which – like RORα – binds cholesterol and is activated by this ligand. Although HR3 is known to be transcriptionally upregulated by the ecdysone steroid hormone EcR, our results reveal that HR3 regulates growth through the TOR pathway in response to cholesterol independently of ecdysone-mediated effects. This regulation involves rapid cholesterol-induced TOR activation that in part is independent of the transcriptional functions of HR3, through an isoform of HR3 that lacks a DNA-binding domain (DBD). Reducing HR3 levels in cells mitigate the overactivation of TOR caused by the intralysosomal accumulation of cholesterol resulting from depletion of Npc1a. This indicates that HR3 is necessary for TOR activation by lysosomal cholesterol. Our findings suggest that HR3 activates the TOR pathway upstream of Rag proteins. Furthermore, our findings indicate that RORα is involved in cholesterol-induced TOR activation in human cells, suggesting that a conserved function of HR3/RORα is to couple cholesterol levels to TOR-pathway activation
Project description:To screen mRNAs specifically regulated by mTORC1, a global mRNA expression profile in colon epithelial cells (CECs) from mice with or without CECs-specific TSC1 knockout (KO) was developed using microarray. Wile-type or CECs-specific TSC1 KO mice with experimental colitis were sacrificed, with CECs harvested and subjected to total RNA extraction.
Project description:Mammalian target of rapamycin (mTOR) complex 1 (mTORC1) is a critical regulator of cell growth by integrating multiple signals (nutrients, growth factors, energy and stress) and is frequently deregulated in many types of cancer. We used a robust experimental paradigm involving the combination of two interventions, one genetic and one pharmacologic to identify genes regulated transcriptionally by mTORC1. In Tsc2+/+, but not Tsc2-/- immortalized mouse embryo fibroblasts (MEFs), serum deprivation downregulates mTORC1 activity. In Tsc2-/- cells, abnormal mTORC1 activity can be downregulated by treatment with rapamycin (sirolimus). By contrast, rapamycin has little effect on mTORC1 in Tsc2+/+ cells in which mTORC1 is already inhibited by low serum. Thus, under serum deprived conditions, mTORC1 activity is low in Tsc2+/+ cells (untreated or rapamycin treated), high in Tsc2-/- cells, but lowered by rapamycin; a pattern referred to as a M-^Slow/low/high/lowM-^T or M-^SLLHLM-^T, which allowed the identification of genes regulated by mTORC1 by performing the appropriate comparisons