Showing papers on "Crypt published in 2017"
TL;DR: A critical role is revealed for the metabolic identity of Lgr5+ CBCs and Paneth cells in supporting optimal stem cell function, and mitochondria and reactive oxygen species signalling are identified as a driving force of cellular differentiation.
Abstract: The small intestinal epithelium self-renews every four or five days. Intestinal stem cells (Lgr5+ crypt base columnar cells (CBCs)) sustain this renewal and reside between terminally differentiated Paneth cells at the bottom of the intestinal crypt. Whereas the signalling requirements for maintaining stem cell function and crypt homeostasis have been well studied, little is known about how metabolism contributes to epithelial homeostasis. Here we show that freshly isolated Lgr5+ CBCs and Paneth cells from the mouse small intestine display different metabolic programs. Compared to Paneth cells, Lgr5+ CBCs display high mitochondrial activity. Inhibition of mitochondrial activity in Lgr5+ CBCs or inhibition of glycolysis in Paneth cells strongly affects stem cell function, as indicated by impaired organoid formation. In addition, Paneth cells support stem cell function by providing lactate to sustain the enhanced mitochondrial oxidative phosphorylation in the Lgr5+ CBCs. Mechanistically, we show that oxidative phosphorylation stimulates p38 MAPK activation by mitochondrial reactive oxygen species signalling, thereby establishing the mature crypt phenotype. Together, our results reveal a critical role for the metabolic identity of Lgr5+ CBCs and Paneth cells in supporting optimal stem cell function, and we identify mitochondria and reactive oxygen species signalling as a driving force of cellular differentiation.
341 citations
TL;DR: It is demonstrated that autocrine IL-6 signaling in the gut epithelium regulates crypt homeostasis through the Paneth cells and the Wnt signaling pathway.
Abstract: Gut homeostasis is a tightly regulated process requiring finely tuned complex interactions between different cell types, growth factors, or cytokines and their receptors. Previous work has implicated a role for IL-6 and mucosal immune cells in intestinal regeneration following injury and in promoting inflammation and cancer. We hypothesized that IL-6 signaling could also modulate crypt homeostasis. Using mouse in vitro crypt organoid and in vivo models, this study first demonstrated that exogenous IL-6 promoted crypt organoid proliferation and increased stem cell numbers through pSTAT3 activation in Paneth cells. Immunolabeling studies showed that the IL-6 receptor was restricted to the basal membrane of Paneth cells both in vitro and in vivo and that the crypt epithelium also expressed IL-6. Either a blocking Ab to the IL-6 receptor or a neutralizing Ab to IL-6 significantly reduced in vitro basal crypt organoid proliferation and budding, and in vivo significantly reduced the number of nuclei and the number of Lgr5EGFP-positive stem cells per crypt compared with IgG-treated mice, with the number of Paneth cells per crypt also significantly reduced. Functional studies demonstrated that IL-6-induced in vitro crypt organoid proliferation and crypt budding was abrogated by the Wnt inhibitor IWP2. This work demonstrates that autocrine IL-6 signaling in the gut epithelium regulates crypt homeostasis through the Paneth cells and the Wnt signaling pathway.
65 citations
TL;DR: The results suggest that chronic stress impairs colon epithelium homeostasis and barrier function via different mechanisms along the crypt axis.
Abstract: Chronic stress and elevated glucocorticoid hormone are associated with decreases in the intestinal epithelial tight junction protein claudin-1 (CLDN1). Human/rat CLDN1 promoters contain glucocorticoid response elements (GREs) and adjacent transcription repressor HES1 binding N-boxes. Notch signaling target HES1 expression was high and glucocorticoid receptor (NR3C1) low at the crypt base and the pattern reversed at the crypt apex. Chronic stress reduced overall rat colon HES1 and NR3C1 that was associated with CLDN1 downregulation. Chromatin-immunoprecipitation experiments showed that HES1 and NR3C1 bind to the CLDN1 promoter in rat colon crypts. The binding of NR3C1 but not HES1 to CLDN1 promoter significantly decreased in chronically stressed animals, which was prevented by the NR3C1 antagonist RU486. We employed the 21-day Caco-2/BBe cell model to replicate cell differentiation along the crypt axis. HES1 siRNA treatment early in differentiation increased CLDN1. In contrast, stress levels of cortisol decreased CLDN1 in late differentiation stage but not in the early stage. HES1 was high, whereas NR3C1 and CLDN1 were low in the early stage which reversed in the late stage, e.g. HES1/NR3C1 binding to CLDN1 promoter demonstrates a dynamic and reciprocal pattern. These results suggest that chronic stress impairs colon epithelium homeostasis and barrier function via different mechanisms along the crypt axis.
54 citations
TL;DR: The existence of crypt fusion is discovered, an almost exact reverse phenomenon of crypt fission, in which 2 crypts fuse into 1 daughter crypt, which could regulate crypt numbers during the lifetime of a mouse.
46 citations
TL;DR: Three-dimensional crypt organoid cultures from genetically modified mouse models are used as an effective in vitro model for studying intestinal drug metabolism and toxicity.
Abstract: The gastrointestinal tract is enriched with xenobiotic processing proteins that play important roles in xenobiotic bioactivation, metabolism, and detoxification. The application of genetically modified mouse models has been instrumental in characterizing the function of xenobiotic processing genes (XPG) and their proteins in drug metabolism. Here, we report the utilization of three-dimensional crypt organoid cultures from these animal models to study intestinal drug metabolism and toxicity. With the successful culturing of crypt organoids, we profiled the abundance of Phase I and Phase II XPG expression, drug transporter gene expression, and xenobiotic nuclear receptor (XNR) gene expression. Functions of XNRs were examined by treating crypt cells with XNR prototypical agonists. Real-time quantitative polymerase chain reaction demonstrated that the representative downstream target genes were induced. These findings were validated from cultures developed from XNR-null mice. In crypt cultures isolated from Pxr-/- mice, pregnenolone 16α-carbonitrile failed to induce Cyp3a11 gene expression; similarly, WY14643 failed to induce Cyp4a10 in the Pparα-/- crypts. Crypt cultures from control (Ugt1F/F ) and intestinal epithelial cell (IEC) specific Ugt1 null mice (Ugt1ΔIEC ) were treated with camptothecin-11, an anticancer prodrug with severe intestinal toxicity that originates from insufficient UGT1A1-dependent glucuronidation of its active metabolite SN-38. In the absence of Ugt1 gene expression, Ugt1ΔIEC crypt cultures exhibit very limited production of SN-38 glucuronide, concordant with increased apoptosis in comparison with Ugt1F/F crypt cultures. This study suggests crypt organoid cultures as an effective in vitro model for studying intestinal drug metabolism and toxicity.
35 citations
TL;DR: It is concluded that exfoliation of crypt epithelium, but not crypt apoptosis, is a major contributor toinflammation in human patients suffering inflammatory bowel disease (IBD).
Abstract: Mice deficient in glutathione peroxidase (GPx)-1 and -2 (GPx1-/-GPx2-/- double knockout or DKO mice) develop very-early-onset (VEO) ileocolitis, suggesting that lack of defense against reactive oxygen species (ROS) renders susceptibility to intestinal inflammation. Two members of ROS-generating NADPH oxidase family, NOX1 and DUOX2, are highly inducible in the intestinal epithelium. Previously, we reported that Nox1 deficiency ameliorated the pathology in DKO mice (Nox1-TKO). The role of Duox2 in ileocolitis of the DKO mice is evaluated here in Duoxa-TKO mice by breeding DKO mice with Duoxa-/- mice (Duoxa-TKO), which do not have Duox2 activity. Similar to Nox1-TKO mice, Duoxa-TKO mice no longer have growth retardation, shortened intestine, exfoliation of crypt epithelium, crypt abscesses and depletion of goblet cells manifested in DKO mice by 35 days of age. Unlike Nox1-TKO mice, Duoxa-TKO mice still have rampant crypt apoptosis, elevated proliferation, partial loss of Paneth cells and diminished crypt density. Treating DKO mice with NOX inhibitors (di-2-thienyliodonium/DTI and thioridazine/THZ) and an antioxidant (mitoquinone/MitoQ) significantly reduced gut pathology. Furthermore, in the inflamed human colon, DUOX protein expression is highly elevated in the apical, lateral and perinuclear membrane along the whole length of gland. Taken together, we conclude that exfoliation of crypt epithelium, but not crypt apoptosis, is a major contributor to inflammation. Both Nox1 and Duox2 induce exfoliation of crypt epithelium, but only Nox1 induces apoptosis. NOX1 and DUOX2 may be potential therapeutic targets for treating ileocolitis in human patients suffering inflammatory bowel disease (IBD).
31 citations
TL;DR: The data argue against the traditional view of ATP as the main cytoprotective factor by glucose metabolism, and indicate a novel anti‐necroptotic role of glycolytic pyruvate under ischaemic stress.
Abstract: Key points
Intestinal ischaemia causes epithelial death and crypt dysfunction, leading to barrier defects and gut bacteria-derived septic complications.
Enteral glucose protects against ischaemic injury; however, the roles played by glucose metabolites such as pyruvate and ATP on epithelial death and crypt dysfunction remain elusive.
A novel form of necrotic death that involves the assembly and phosphorylation of receptor interacting protein kinase 1/3 complex was found in ischaemic enterocytes.
Pyruvate suppressed epithelial cell death in an ATP-independent manner and failed to maintain crypt function. Conversely, replenishment of ATP partly restored crypt proliferation but had no effect on epithelial necroptosis in ischaemic gut.
Our data argue against the traditional view of ATP as the main cytoprotective factor by glucose metabolism, and indicate a novel anti-necroptotic role of glycolytic pyruvate under ischaemic stress.
Abstract
Mesenteric ischaemia/reperfusion induces epithelial death in both forms of apoptosis and necrosis, leading to villus denudation and gut barrier damage. It remains unclear whether programmed cell necrosis [i.e. receptor-interacting protein kinase (RIP)-dependent necroptosis] is involved in ischaemic injury. Previous studies have demonstrated that enteral glucose uptake by sodium-glucose transporter 1 ameliorated ischaemia/reperfusion-induced epithelial injury, partly via anti-apoptotic signalling and maintenance of crypt proliferation. Glucose metabolism is generally assumed to be cytoprotective; however, the roles played by glucose metabolites (e.g. pyruvate and ATP) on epithelial cell death and crypt dysfunction remain elusive. The present study aimed to investigate the cytoprotective effects exerted by distinct glycolytic metabolites in ischaemic gut. Wistar rats subjected to mesenteric ischaemia were enterally instilled glucose, pyruvate or liposomal ATP. The results showed that intestinal ischaemia caused RIP1-dependent epithelial necroptosis and villus destruction accompanied by a reduction in crypt proliferation. Enteral glucose uptake decreased epithelial cell death and increased crypt proliferation, and ameliorated mucosal histological damage. Instillation of cell-permeable pyruvate suppressed epithelial cell death in an ATP-independent manner and improved the villus morphology but failed to maintain crypt function. Conversely, the administration of liposomal ATP partly restored crypt proliferation but did not reduce epithelial necroptosis and histopathological injury. Lastly, glucose and pyruvate attenuated mucosal-to-serosal macromolecular flux and prevented enteric bacterial translocation upon blood reperfusion. In conclusion, glucose metabolites protect against ischaemic injury through distinct modes and sites, including inhibition of epithelial necroptosis by pyruvate and the promotion of crypt proliferation by ATP.
25 citations
TL;DR: Altered mAChR signaling causes change in ileal mucosal morphometry and crypt cell proliferation, and mA cholinergic nervous system pathways appear to be critical for mucosal homeostasis.
23 citations
TL;DR: Systemic, but not intestinal-specific, m TORC1 is important for normal adaptation responses to SBR, and forced enterocyte mTORC1 signaling after resection causes an enhanced adaptive response.
Abstract: Background & Aims Intestinal adaptation is a compensatory response to the massive loss of small intestine after surgical resection. We investigated the role of intestinal epithelial cell–specific mammalian target of rapamycin complex 1 (i-mTORC1) in intestinal adaptation after massive small bowel resection (SBR). Methods We performed 50% proximal SBR on mice to study adaptation. To manipulate i-mTORC1 activity, Villin-CreER transgenic mice were crossed with tuberous sclerosis complex (TSC)1flox/flox or Raptorflox/flox mice to inducibly activate or inactivate i-mTORC1 activity with tamoxifen. Western blot was used to confirm the activity of mTORC1. Crypt depth and villus height were measured to score adaptation. Immunohistochemistry was used to investigate differentiation and rates of crypt proliferation. Results After SBR, mice treated with systemic rapamycin showed diminished structural adaptation, blunted crypt cell proliferation, and significant body weight loss. Activating i-mTORC1 via TSC1 deletion induced larger hyperproliferative crypts and disorganized Paneth cells without a significant change in villus height. After SBR, ablating TSC1 in intestinal epithelium induced a robust villus growth with much stronger crypt cell proliferation, but similar body weight recovery. Acute inactivation of i-mTORC1 through deletion of Raptor did not change crypt cell proliferation or mucosa structure, but significantly reduced lysozyme/matrix metalloproteinase-7–positive Paneth cell and goblet cell numbers, with increased enteroendocrine cells. Surprisingly, ablation of intestinal epithelial cell–specific Raptor after SBR did not affect adaptation or crypt proliferation, but dramatically reduced body weight recovery after surgery. Conclusions Systemic, but not intestinal-specific, mTORC1 is important for normal adaptation responses to SBR. Although not required, forced enterocyte mTORC1 signaling after resection causes an enhanced adaptive response.
21 citations
TL;DR: Information from recent studies on Wnt-expressing cells and intestinal fibroblast lineages are integrated and their roles in homeostasis and wound healing are discussed to clarify the mechanisms of epithelial tissue formation.
Abstract: The crypt is a minimal functional unit in the intestinal epithelium. This unique structure is maintained by surrounding mesenchymal cells that focally interact with associated epithelial cells. Canonical and non-canonical Wnt ligands enable specific microenvironments localized to each end of the crypt major axis. While canonical Wnt-expressing cells are localized near the crypt bottom where intestinal stem cells reside, non-canonical Wnt-expressing cells are positioned beneath the luminal surface of epithelial cells. During wound healing, propagation and appropriate relocation of each cell population are thought to ensure subsequent crypt regeneration. In this review, I integrate information from recent studies on Wnt-expressing cells and intestinal fibroblast lineages and discuss their roles in homeostasis and wound healing. More information on the lineages of Wnt-expressing cells will help clarify the mechanisms of epithelial tissue formation.
19 citations
TL;DR: A computational model is described which includes novel features, including an accurate representation of the geometry of the crypt mouth, and a mechanism emerges in the model for regulation of crypt cellularity in response to changes in either cell proliferation rates or membrane adhesion strengths.
Abstract: Colorectal cancer (CRC) is a major cause of cancer mortality. Colon crypts are multi-cellular flask-shaped invaginations of the colonic epithelium, with stem cells at their base which support the continual turnover of the epithelium with loss of cells by anoikis from the flat mucosa. Mutations in these stem cells can become embedded in the crypts, a process that is strongly implicated in CRC initiation. We describe a computational model which includes novel features, including an accurate representation of the geometry of the crypt mouth. Model simulations yield previously unseen emergent phenomena, such as localization of cell death to a small region of the crypt mouth which corresponds with that observed in vivo. A mechanism emerges in the model for regulation of crypt cellularity in response to changes in either cell proliferation rates or membrane adhesion strengths. We show that cell shape assumptions influence this behaviour, with cylinders recapitulating biology better than spheres. Potential applications of the model include determination of roles of mutations in neoplasia and exploring factors for altered crypt morphodynamics.
TL;DR: Muscarinic receptors are widely distributed along the entire alimentary tract and only mAChR2 clearly localized to the crypt stem cell compartment, specifically co‐localizing with Paneth cells at crypt bases, suggesting it is a plausible regulator of stem cell activity.
TL;DR: It is found that short-term changes in food intake in vivo or glucose availability in vitro dictate the mode of division of crypt cells and that LKB1-AMPK signaling modulates the glucose-induced changes in the Mode of division in vitro.
Abstract: Nutrient availability influences intestinal epithelial stem cell proliferation and tissue growth. Increases in food result in a greater number of epithelial cells, villi height and crypt depth. We investigated whether this nutrient-driven expansion of the tissue is the result of a change in the mode of intestinal epithelial stem cell division and if LKB1-AMPK signaling plays a role. We utilized in vivo and in vitro experiments to test this hypothesis. C57BL/6J mice were separated into four groups and fed varying amounts of chow for 18 h: (1) ad libitum, (2) 50% of their average daily intake (3) fasted or (4) fasted for 12 h and refed. Mice were sacrificed, intestinal sections excised and immunohistochemically processed to determine the mitotic spindle orientation. Epithelial organoids in vitro were treated with no (0 mM), low (5 mM) or high (20 mM) amounts of glucose with or without an activator (Metformin) or inhibitor (Compound C) of LKB1-AMPK signaling. Cells were then processed to determine the mode o...
TL;DR: Enhancing 5-HT signaling in mice increases VH, CD, EH, and crypt cell proliferation in the intestinal mucosa and holds promise as a target for therapies aimed at enhancing intestinal recovery after injury or mucosal surface area loss.
06 Jan 2017
TL;DR: The assay was used to identify bioactive compounds, which served as probes to interrogate the biology of crypt organoids over prolonged culture, and the pathways that are changing over time may offer potential targets for treatment of mucositis.
Abstract: Oral and intestinal mucositis is a debilitating side effect of radiation treatment. A mouse model of radiation-induced mucositis leads to weight loss and tissue damage, reflecting the human ailment as it responds to keratinocyte growth factor (KGF), the standard-of-care treatment. Cultured intestinal crypt organoids allowed the development of an assay monitoring the effect of treatments of intestinal epithelium to radiation-induced damage. This in vitro assay resembles the mouse model as KGF and roof plate-specific spondin-1 (RSPO1) enhanced crypt organoid recovery following radiation. Screening identified compounds that increased the survival of organoids postradiation. Testing of these compounds revealed that the organoids changed their responses over time. Unbiased transcriptome analysis was performed on crypt organoid cultures at various time points in culture to investigate this adaptive behavior. A number of genes and pathways were found to be modulated over time, providing a rationale for the altered sensitivity of the organoid cultures. This report describes an in vitro assay that reflects aspects of human disease. The assay was used to identify bioactive compounds, which served as probes to interrogate the biology of crypt organoids over prolonged culture. The pathways that are changing over time may offer potential targets for treatment of mucositis.
TL;DR: It is suggested that crypt-transformed plants can also be used as a tool to elucidate the biochemical basis of defense responses as phenolics are known to play a role in providing defense barriers to infection by pathogen.
Abstract: Tylophora indica, an indigenous medicinal plant, was transformed with the cryptogein gene to determine the effect of crypt gene on secondary metabolites in co-transformed roots and plants via Agrobacterium rhizogenes mediated transformation. The Ri crypt co-transformed roots and plants showed expression of crypt gene. Southern hybridization specifies that crypt gene has been transferred and positively integrated into the Ri crypt co-transformed plant. AFLP fingerprinting revealed high degree of genetic similarity among the Ri-transformed and Ri crypt co-transformed cultures. The expression of crypt gene stimulated phenolic compound accumulation in transformed root and plants while tylophorine content was comparable in Ri transformed and Ri crypt co-transformed root lines and plants. The Ri crypt co-transformed root lines showed significantly higher (p ≤ 0.05) phenolics production (caffeic acid, 1.8–2.9-fold; p-coumaric acid, 1.9-fold and ferulic acid, 1.5–2-fold) compared to Ri-transformed root lines. The roots of Ri crypt co-transformed plants showed a significantly (p ≤ 0.05) higher content of caffeic acid (1.19-fold) and ferulic acid (1.53-fold) than Ri-transformed plants. It is suggested that crypt-transformed plants can also be used as a tool to elucidate the biochemical basis of defense responses as phenolics are known to play a role in providing defense barriers to infection by pathogen.
TL;DR: A novel mouse model for studying the long-term trajectory of radiation-induced gut injury, which allows for the use of high doses and multiple fractions, with minor impact on animal health for at least 3 mo, is established.
Abstract: A deeper understanding of the radiation-induced pathophysiological processes that develop in the gut is imperative to prevent, alleviate, or eliminate cancer survivorship diseases after radiotherapy to the pelvic area. Most rodent models of high-dose gastrointestinal radiation injury are limited by high mortality. We therefore established a model that allows for the delivering of radiation in fractions at high doses while maintaining long-term survival. Adult male C57/BL6 mice were exposed to small-field irradiation, restricted to 1.5 cm of the colorectum using a linear accelerator. Each mouse received 6 or 8 Gy, two times daily in 12-h intervals in two, three, or four fractions. Acute cell death was examined at 4.5 h postirradiation and histological changes at 6 wk postirradiation. Another group was given four fractions of 8 Gy and followed over time for development of visible symptoms. Irradiation caused immediate cell death, mainly limited to the colorectum. At 6 wk postirradiation, several crypts displayed signs of radiation-induced degeneration. The degenerating crypts were seen alongside crypts that appeared perfectly healthy. Crypt survival was reduced after the fourth fraction regardless of dose, whereas the number of macrophages increased. Angiogenesis was induced, likely as a compensatory mechanism for hypoxia. Four months postirradiation, mice began to show radiation-induced symptoms, and histological examination revealed an extensive crypt loss and fibrosis. Our model is uniquely suitable for studying the long-term trajectory and underlying mechanisms of radiation-induced gastrointestinal injury.NEW & NOTEWORTHY A novel mouse model for studying the long-term trajectory of radiation-induced gut injury. The method allows for the use of high doses and multiple fractions, with minor impact on animal health for at least 3 mo. Crypt loss and a slow progression of fibrosis is observed. Crypt degeneration is a process restricted to isolated crypts. Crypt degeneration is presented as a convenient proxy endpoint for long-term radiation-induced gut injury.
TL;DR: The findings support the possibility that crypt cells are functionally less uniform as supposed in zebrafish, and documented that calretinin, a known marker of zebra fish ciliated and microvillous olfactory cells, in the guppy is expressed also by a subpopulation of S100-positive crypt neurons.
Abstract: Olfactory crypt neurons have been observed in several bony fishes and chondrichtyans. Although their morphology is uniform in all fish, very few is known about their antigenic properties, usually studied in zebrafish, but quite overlooked in other species. We tested in Poecilia reticulata (guppy) the two antibodies recognized to mark zebrafish crypt cells: while anti-S100 showed an immunohistochemical pattern comparable to what reported in zebrafish, anti-TrkA gave no signal. Western blot analysis revealed that S100-antiserum bound an antigen of expected weight, probably belonging to the S100 family. On the contrary, anti-TrkA detected more bands, but the protein/s might be too much diffused and/or diluted in the tissue to be detected with immunohistochemistry. Because of the high level of conservation in the Trk family proteins of the kinase domain, on which anti-TrkA was produced, we also tested anti-TrkB to exclude cross reactivity. Immunohistochemistry and Western blot confirmed that anti-TrkB displayed high specificity to its target and a different staining pattern compared to anti-TrkA, but, as anti-TrkA, it did not label crypt neurons. Finally, we documented that calretinin, a known marker of zebrafish ciliated and microvillous olfactory cells, in the guppy is expressed also by a subpopulation of S100-positive crypt neurons. These results reveal differences in antigen expression between zebrafish and guppy crypt cells. Together with the already known species-specific projections to the olfactory bulb and a heterogeneous panel of odorants, our findings support the possibility that crypt cells are functionally less uniform as supposed.
TL;DR: The results indicate that for certain parameters the crypt is in a homeostatic state, but slight changes on their values can disrupt this behaviour.
Abstract: We present a theoretical and computational framework to model the colonic crypt organisation in the human intestine. We construct a theoretical and computational framework to model the colonic crypt behaviour, using a Voronoi tessellation to represent each cell and elastic forces between them we addressed how their dynamical disfunction can lead to tumour masses and cancer. Our results indicate that for certain parameters the crypt is in a homeostatic state, but slight changes on their values can disrupt this behaviour.
TL;DR: A new computational model of the colonic crypt has been developed and suggests that Apc loss confers a survival advantage at the crypt mouth which may be a previously unknown method of mutation fixation.
TL;DR: It is shown that sepsis unmasks compartment‐specific proliferative and apoptotic regulation that is not present under homeostatic conditions.
Abstract: Cell production and death are tightly regulated in the rapidly renewing gut epithelium, with proliferation confined to crypts and apoptosis occurring in villi and crypts. This study sought to determine how stress alters these compartmentalized processes. Wild-type mice made septic via cecal ligation and puncture had decreased crypt proliferation and increased crypt and villus apoptosis. Fabpi-TAg mice expressing large T-antigen solely in villi had ectopic enterocyte proliferation with increased villus apoptosis in unmanipulated animals. Septic fabpi-TAg mice had an unexpected increase in villus proliferation compared with unmanipulated littermates, whereas crypt proliferation was decreased. Cell cycle regulators cyclin D1 and cyclin D2 were decreased in jejunal tissue in septic transgenic mice. In contrast, villus and crypt apoptosis were increased in septic fabpi-TAg mice. To examine the relationship between apoptosis and proliferation in a compartment-specific manner, fabpi-TAg mice were crossed with fabpl-Bcl-2 mice, resulting in expression of both genes in the villus but Bcl-2 alone in the crypt. Septic bi-transgenic animals had decreased crypt apoptosis but had a paradoxical increase in villus apoptosis compared with septic fabpi-TAg mice, associated with decreased proliferation in both compartments. Thus, sepsis unmasks compartment-specific proliferative and apoptotic regulation that is not present under homeostatic conditions.-Lyons, J. D., Klingensmith, N. J., Otani, S., Mittal, R., Liang, Z., Ford, M. L., Coopersmith, C. M. Sepsis reveals compartment-specific responses in intestinal proliferation and apoptosis in transgenic mice whose enterocytes re-enter the cell cycle.
TL;DR: Crypt cell motion was reduced with inhibition of the ROCK pathway and attenuated with old age, and both resulted in incomplete pattern recovery, which suggests that in addition to proliferation and self-renewal, motility of stem cells is critical for maintaining homeostasis.
Abstract: Despite the continuous renewal and turnover of the small intestinal epithelium, the intestinal stem cell niche maintains a soccer ball-like, alternating pattern of stem and Paneth cells in the crypt. To study the robustness of the niche pattern, we used intravital two-photon microscopy in mice with fluorescently-labeled Lgr5+ intestinal stem cells and precisely perturbed the mosaic pattern with femtosecond laser ablation. Ablation of one to three cells initiated rapid motion of niche cells that restored the alternation in the crypt pattern within about two hours without any cell proliferation. Crypt cells then performed a coordinated dilation of the crypt lumen, which resulted in peristalsis-like motion that forced damaged cells out of the niche. Crypt cell motion was reduced with inhibition of the ROCK pathway and attenuated with old age, and both resulted in incomplete pattern recovery. This suggests that in addition to proliferation and self-renewal, motility of stem cells is critical for maintaining homeostasis. Reduction of this novel behavior of stem cells could contribute to disease and age-related changes.
TL;DR: The data presented in this article are related to the research article entitled “Distribution of muscarinic acetylcholine receptor subtypes in the murine small intestine”, which demonstrated that neuronal serotonin stimulates intestinal crypt cell division, and induces villus growth and crypt depth.
TL;DR: Food-grade TIO2 pigment initiates preneoplastic lesions and promotes aberrant crypt development in the rat Colon during Digestive Disease Week.