Project description:Tuft cells are an epithelial cell subset critical for initiating type 2 immune responses to parasites and protozoa in the small intestine. To respond to these stimuli, intestinal tuft cells use taste chemosensory signaling pathways, but the role of taste receptors in type 2 immunity is poorly understood. Here, we show that the taste receptor TAS1R3, which detects sweet and umami in the tongue, also regulates tuft cell responses in the distal small intestine. BALB/c mice, which have an inactive form of TAS1R3, as well as Tas1r3-deficient C57BL6/J mice both have severely impaired responses to tuft cell-inducing signals in the ileum including the protozoa Tritrichomonas muris and succinate. In contrast, TAS1R3 is not required to mount an immune response to the helminth Heligmosomoides polygyrus, which infects the proximal small intestine. Examination of uninfected Tas1r3-/- mice revealed a modest reduction in the number of tuft cells in the proximal small intestine but a severe decrease in the distal small intestine at homeostasis. Together, these results suggest that TAS1R3 influences intestinal immunity by shaping the epithelial cell landscape at steady state.
Project description:The transient receptor potential melastatin type 6 (TRPM6) is a divalent cation channel pivotal for gatekeeping Mg2+ balance. To study the role of TRPM6 in the intestine, we generated mice lacking intestinal TRPM6 (Vill1-TRPM6-/-). In this study, the distal colon of Vill1-TRPM6-/- mice and of the control mice (TRPM6fl/fl) was subjected to RNA sequencing.
Project description:The ability to generate defined null mutations in mice revolutionized the analysis of gene function in mammals. However, gene-deficient mice generated by using 129-derived embryonic stem (ES) cells may carry large segments of 129 DNA, even when extensively backcrossed to reference strains, such as C57BL/6J, and this may confound interpretation of experiments performed in these mice. Tissue plasminogen activator (tPA), encoded by the PLAT gene, is a fibrinolytic serine protease that is widely expressed in the brain. A large number of neurological abnormalities have been reported in tPA-deficient mice. The studies here compare genes differentially expressed in the brains of Plat-/- mice from two independent Plat-/- mouse derivations to wild-type C57BL/6J mice. One strain denoted “Old” was constructed in ES cells from a 129 mouse and backcrossed extensively to C57BL/6J, and one denoted “New” Plat-/- mouse was constructed using zinc finger nucleases directly in the C57BL/6J-Plat-/- mouse strain. We identify a significant set of genes that are differentially expressed in the brains of Old Plat-/- mice that preferentially cluster in the vicinity of Plat on chromosome 8, apparently linked to more than 20 Mbp of DNA flanking Plat being of 129 origin. No such clustering is seen in the New Plat-/- mice.
Project description:Endogenous retroviruses (ERVs) are transposable elements that cause host genome instability and usually play deleterious roles such as tumorigenesis. Recent advances also suggest that this 'enemy within' may encode viral mimic to induce antiviral immune responses through viral sensors. Here, through whole genome RNA-seq we discovered a full-length ERV-derived long non-coding RNA (lncRNA), designated lnc-EPAV (ERV-derived lncRNA positively regulates antiviral responses), as a positive regulator of NF-κB signaling. Lnc-EPAV expression was rapidly up-regulated by viral RNA mimic or RNA viruses to facilitate the expression of RELA, an NF-κB subunit that plays a critical role in antiviral responses. In turn, RELA promoted the transcription of lnc-EPAV to form a positive feedback loop. Transcriptome analysis of lnc-EPAV-silenced macrophages, combined with gain- and loss-of-function experiments, showed that lnc-EPAV was critical for induction of type I interferon (IFN) and inflammatory cytokine expression by RNA viruses. Consistently, lnc-EPAV-deficient mice exhibited reduced expression of type I IFNs, and consequently increased viral loads and mortality following lethal RNA virus infection. Mechanistically, lnc-EPAV promoted expression of RELA by competitively binding to and displacing SFPQ, a transcriptional repressor of RELA. The binding between ERV-derived RNAs and SFPQ also existed in human cells. Altogether, our work demonstrates an alternative mechanism by which ERVs regulate antiviral immune responses.
Project description:By regulating digestion and absorption of nutrients and providing a barrier against the external environment the intestine provides a crucial contribution to the maintenance of health. To what extent aging-related changes in the intestinal system contribute to the impaired health of the aging body is still under debate. Young (4 months) and old (21 months) male C57BL/6J mice were fed a control low-fat (10E%) or a high-fat diet (45E%) for 2 weeks. During the intervention gross energy intake and energy excretion in the feces were measured. After sacrifice the small and large intestine were isolated whereby the small intestine was divided in three equal parts. Of each of the isolated segments Swiss rolls were prepared for histological analysis and the luminal content was isolated to examine alterations in the microflora with 16S rRNA Q-PCR. Furthermore, mucosal scrapings were isolated from each segment to determine differential gene expression by microarray analysis and global DNA methylation by pyrosequencing. Digestible energy intake was similar between the two age groups on both the control and the high-fat diet implying that macronutrient metabolism is not affected in 21-month-old mice. This observation was supported by the fact that the microarray analysis on RNA from intestinal scrapings showed no marked changes in expression of genes involved in metabolic processes. Decreased expression of Cubilin was observed in the intestine of 21-month-old mice, which might contribute to aging-induced vitamin B12 deficiency. Furthermore, microarray data analysis revealed enhanced expression of a high number of genes involved in immune response and inflammation in the colon, but not in the small intestine of the 21-month-old mice. Aging-induced global hypomethylation was observed in the colon and the distal part of the small intestine, but not in the first two sections of the small intestine. In 21-month old mice the most pronounced effects of aging was observed in the colon, limited changes were observed in the small intestine. Young (4M) and old (21M) wild type C57BL/6J mice were fed a low-fat diet or high-fat diet for 2 weeks. After the diet intervention period, the animals were killed and scrapings were made of the colon. Total RNA was isolated and subjected to gene expression profiling.
Project description:Obesity and insulin resistance are two major risk factors underlying the metabolic syndrome. To gain more insight in the role of the small intestine in the etiology of these metabolic disorders, a microarray study was performed on small intestines (SI) of C57BL/6J mice that were fed a high fat diet mimicking the fatty acid composition of a Western-style human diet. The mice became obese and developed dietary fat-induced glucose intolerance. For gene expression profiling, the small intestines were subdivided in three equal parts along the longitudinal axis. The most pronounced effects of dietary fat were detected in part 2 of the small intestine. The biological processes that were most extensively modulated on a high fat diet were related to lipid metabolism, especially β- and ω-fatty acid oxidation seemed to play an important role, cell cycle and inflammation/immune response. An additional secretome analysis revealed differentially expressed secreted proteins, such as Il18, Ffgf15, Mif, Igfbp3 and Angptl4, which might provoke systemic effects in peripheral organs by influencing their metabolic homeostasis. Furthermore, many of the dietary fat-modulated genes and biological processes in small intestine were previously already associated with obesity and/or insulin resistance. Together, the data of this exploratory study provided various leads for an essential role of the small intestine in development of obesity and/or insulin resistance. Keywords: time course
Project description:Box C/D-type small nucleolar RNAs (snoRNAs) are functional RNAs responsible for mediating 2’-O-ribose methylation of ribosomal RNAs (rRNAs) within the nucleolus. Previously, in relation to a novel chromosomal translocation in a human B-cell lymphoma, we identified U50HG, a non-protein-coding gene that hosted a box C/D-type U50 snoRNA within its intron. To investigate the physiological importance of the U50 snoRNA and its involvement in tumorigenesis, we generated a mouse model deficient in mouse U50 (mU50) snoRNA expression without altering the expression of mouse mU50 host-gene, mU50HG-b. The established mU50 snoRNA-deficient mice showed a significant reduction of mU50 snoRNA expression and the corresponding target rRNA methylation in various organs. Lifelong phenotypic monitoring showed that the mU50-deficient mice looked almost normal without accelerated tumorigenicity; however, a notable difference was the propensity for anomalies in the lymphoid organs. B-cells were isolated from spleens of DmU50(HG-b) mice or wild-type C57BL/6J with antibody-conjugated magnetic beads system (Myltenyi Biotec). Total RNA was purified with QIAGEN RNeasy Micro kit. Affymetrix GeneChip® Microarrays (Mouse Expression 430 2.0 Array) were used.