Project description:Oncogenic mutations that drive colorectal cancer can be present in healthy intestines for long periods without overt consequence. Mutation of Adenomatous polyposis coli (Apc), the most common initiating event in conventional adenomas, activates Wnt signaling, hence conferring fitness on mutant intestinal stem cells (ISCs). Apc mutations may occur in ISCs that arose by routine self-renewal or by dedifferentiation of their progeny. Although ISCs of these different origins are fundamentally similar, it is unclear if both generate tumours equally well in uninjured intestines. Also unknown is whether cis-regulatory elements are substantively modulated upon Wnt hyperactivation or as a feature of subsequent tumours. Here, we show in two mouse models that adenomas are not an obligatory outcome of Apc deletion in either ISC source but require proximity of mutant intestinal crypts. Reduced crypt density abrogates, and aggregation of mutant colonic crypts augments, adenoma formation. Moreover, adenoma-resident ISCs open chromatin at thousands of enhancers that are inaccessible in Apc-null ISCs not associated with adenomas. These cis-elements explain adenoma-selective gene activity and persist, with little further expansion of the repertoire, as other oncogenic mutations accumulate. Thus, cooperativity between neighbouring mutant crypts and new accessibility at specific enhancers are key steps early in intestinal tumourigenesis.
Project description:Paneth cells originate in the stem cell region near the bottom of the gland and release a large number of secretory granules containing antimicrobials. The antimicrobial-rich granules are discharged into the crypt lumen and prevent microbial invasion of the crypt and defend the gland stem cells from microbial damage. We examined the global gene expression profiles in crypt IECs using the Clariom S sDNA array. We analyzed mRNA panels of antimicrobial peptides (AMPs) produced in CSN8ΔIEC and CSN8fl/fl mice.
Project description:Transcriptional profiling of jejunal gene expression during the differentiation from crypt to villus cells in rats, using cryostat sections of the villus-crypt columns.
Project description:Skeletal homeostasis if profoundly altered in response to multiple-myeloma tumour burden. Osteocytes are pivotal regulatory cells in skeletal homeostasis. This dataset was used to examine the differences in the osteocyte-specific transcriptome that may underlie the changes in skeletal homeostasis that occur with multiple myeloma tumour burden. We performed total-RNA transcriptome sequencing on the isolated osteocytes from tumour-burdened and naive bone samples, as well as the marrow from these samples. With this experimental design we can identify genes that are changed specifically in osteocytes in the presence of multiple myeloma tumour burden.
Project description:Signals from the surrounding niche drive proliferation and suppress differentiation of intestinal stem cells (ISCs) at the bottom of intestinal crypts. Among sub-epithelial support cells, deep sub-cryptal CD81+ PDGFRAlo trophocytes alone sustain ISC functions ex vivo. Here we show that mRNA and chromatin profiles of abundant CD81- PDGFRAlo stromal cells resemble those of trophocytes and that both populations provide crucial canonical Wnt ligands. Mesenchymal expression of key ISC-supportive factors extends along a spatial and molecular continuum from trophocytes into peri-cryptal CD81- CD55hi cells, which mimic trophocyte activity in organoid co-cultures. Graded expression of essential niche factors is not cell-autonomous but dictated by the distance from bone morphogenetic protein (BMP)-secreting PDGFRAhi myofibroblast aggregates. BMP signaling inhibits ISC-trophic genes in PDGFRAlo cells near high crypt tiers and that suppression is relieved in stromal cells near and below the crypt base, including trophocytes. Cell distances thus underlie a self-organized and polar ISC niche.
Project description:Signals from the surrounding niche drive proliferation and suppress differentiation of intestinal stem cells (ISCs) at the bottom of intestinal crypts. Among sub-epithelial support cells, deep sub-cryptal CD81+ PDGFRAlo trophocytes capably sustain ISC functions ex vivo. Here we show that mRNA and chromatin profiles of abundant CD81- PDGFRAlo mouse stromal cells resemble those of trophocytes and that both populations provide crucial canonical Wnt ligands. Mesenchymal expression of key ISC-supportive factors extends along a spatial and molecular continuum from trophocytes into peri-cryptal CD81- CD55hi cells, which mimic trophocyte activity in organoid co-cultures. Graded expression of essential niche factors is not cell-autonomous but dictated by the distance from bone morphogenetic protein (BMP)-secreting PDGFRAhi myofibroblast aggregates. BMP signaling inhibits ISC-trophic genes in PDGFRAlo cells near high crypt tiers; that suppression is relieved in stromal cells near and below the crypt base, including trophocytes. Cell distances thus underlie a self-organized and polar ISC niche.
Project description:We used the mouse pathogen Citrobacter rodentium to model gut infections. Following oral inoculation C. rodentium resides in the caecum for the first 3 days, before it infects the colon on the 4th day. Here we show that while the host is unresponsive to the infection on day 3, there is an abrupt reprogramming of the cellular composition of the crypt, involving depletion of goblet and deep crypt secretory cells, as well as metabolism (e.g. simultaneous up-regulation of cholesterol biogenesis, import and efflux), DNA damage repair and proliferation, which correlated with Ki67 staining, on day 4. Reduction in the abundance of proteins involved in the TCA cycle and oxidative phosphorylation, leading to oxygenation of the gut, coincided with instant expansion of mucosal-associated Enterobacteriaceae. These results show that sensing a small number of pathogenic bacteria triggers immediate intrinsic changes to the epithelium physiology and the microbiota, which parallel innate gut immune responses.
Project description:At the base of the intestinal crypt, long-lived Lgr5+ stem cells are intercalated by Paneth cells that provide essential niche signals for stem-cell maintenance. This unique epithelial anatomy makes the intestinal crypt one of the most accessible models for the study of adult stem cell biology. The glycosylation patterns of this compartment are poorly characterized and the impact of glycans on stem cell differentiation remains largely unexplored. We found that Paneth cells, but not Lgr5+ stem cells, express abundant terminal N-acetyllactosamine (LacNAc). Employing an enzymatic method to edit glycans in cultured crypt organoids, we assessed the functional role of LacNAc in the intestinal crypt. We show that blocking access to LacNAc on Paneth cells leads to hyperproliferation of the neighbouring Lgr5+ stem cells, which is accompanied by the down-regulation of genes that are known as negative regulators of proliferation
Project description:In the mammalian intestine, crypts of Leiberkühn house intestinal epithelial stem /progenitor cells at their base. We found that the presence of this structure was supported by the physiologic role of a prominent bacterial metabolite, butyrate. This bacterially-produced short chain fatty acid inhibited intestinal epithelial proliferation at physiologic concentrations. During homeostasis, butyrate did not suppress epithelial stem proliferation because it was metabolized by differentiated colonocytes. Provision of butyrate access to stem/progenitor cells either through mucosal injury or application to a crypt-less host led to inhibition of proliferation. The mechanism was dependent on HDAC inhibition in stem cells and the transcription factor Foxo3. Thus, the mammalian crypt unit structure provides energy for differentiated cells at a distance from the crypt base and this action prevents suppression of stem/progenitor proliferation.