Wnt signaling is boosted during intestinal regeneration by a CD44-positive feedback loop.

Enhancement of Wnt signaling is fundamental for stem cell function during intestinal regeneration. Molecular modules control Wnt activity by regulating signal transduction. CD44 is such a positive regulator and a Wnt target gene.

Lef1 restricts ectopic crypt formation and tumor cell growth in intestinal adenomas.

Somatic mutations in or genes lead to aberrant Wnt signaling and colorectal cancer (CRC) initiation and progression via-catenin–T cell factor/lymphoid enhancer binding factor TCF/LEF transcription factors. We found that was expressed exclusively in -mutant, Wnt ligand–independent tumors, but not in ligand-dependent, serrated tumors. To analyze function in tumor development, we conditionally deleted in intestinal stem cells of mice or broadly from the entire intestinal epithelium of or mice.

Oncogenic BRAF, unrestrained by TGFβ-receptor signalling, drives right-sided colonic tumorigenesis.

Right-sided (proximal) colorectal cancer (CRC) has a poor prognosis and a distinct mutational profile, characterized by oncogenic BRAF mutations and aberrations in mismatch repair and TGFβ signalling. Here, we describe a mouse model of right-sided colon cancer driven by oncogenic BRAF and loss of epithelial TGFβ-receptor signalling. The proximal colonic tumours that develop in this model exhibit a foetal-like progenitor phenotype (Ly6a/Sca1) and, importantly, lack expression of Lgr5 and its associated intestinal stem cell signature.

NOTUM from Apc-mutant cells biases clonal competition to initiate cancer.

The tumour suppressor APC is the most commonly mutated gene in colorectal cancer. Loss of Apc in intestinal stem cells drives the formation of adenomas in mice via increased WNT signalling, but reduced secretion of WNT ligands increases the ability of Apc-mutant intestinal stem cells to colonize a crypt (known as fixation). Here we investigated how Apc-mutant cells gain a clonal advantage over wild-type counterparts to achieve fixation.

Subversion of Niche-Signalling Pathways in Colorectal Cancer: What Makes and Breaks the Intestinal Stem Cell.

The intestinal epithelium fulfils pleiotropic functions in nutrient uptake, waste elimination, and immune surveillance while also forming a barrier against luminal toxins and gut-resident microbiota. Incessantly barraged by extraneous stresses, the intestine must continuously replenish its epithelial lining and regenerate the full gamut of specialized cell types that underpin its functions. Homeostatic remodelling is orchestrated by the intestinal stem cell (ISC) niche: a convergence of epithelial- and stromal-derived cues, which maintains ISCs in a multipotent state.

Expression of R-Spondin 1 in Apc Mice Suppresses Growth of Intestinal Adenomas by Altering Wnt and Transforming Growth Factor Beta Signaling.

Background & Aims: Mutations in the APC gene and other genes in the Wnt signaling pathway contribute to development of colorectal carcinomas. R-spondins (RSPOs) are secreted proteins that amplify Wnt signaling in intestinal stem cells. Alterations in RSPO genes have been identified in human colorectal tumors.

MCL1 Is Required for Maintenance of Intestinal Homeostasis and Prevention of Carcinogenesis in Mice.

Background & Aims: Intestinal epithelial homeostasis depends on a tightly regulated balance between intestinal epithelial cell (IEC) death and proliferation. While the disruption of several IEC death regulating factors result in intestinal inflammation, the loss of the anti-apoptotic BCL2 family members BCL2 and BCL2L1 has no effect on intestinal homeostasis in mice. We investigated the functions of the antiapoptotic protein MCL1, another member of the BCL2 family, in intestinal homeostasis in mice.

Author Correction: Loss of BCL9/9l suppresses Wnt driven tumourigenesis in models that recapitulate human cancer.

The original version of this Article contained an error in the spelling of the author Miryam Müller, which was incorrectly given as Miryam Müeller. This has now been corrected in both the PDF and HTML versions of the Article.

RAL GTPases Drive Intestinal Stem Cell Function and Regeneration through Internalization of WNT Signalosomes.

Ral GTPases are RAS effector molecules and by implication a potential therapeutic target for RAS mutant cancer. However, very little is known about their roles in stem cells and tissue homeostasis. Using Drosophila, we identified expression of RalA in intestinal stem cells (ISCs) and progenitor cells of the fly midgut.

Loss of BCL9/9l suppresses Wnt driven tumourigenesis in models that recapitulate human cancer.

Different thresholds of Wnt signalling are thought to drive stem cell maintenance, regeneration, differentiation and cancer. However, the principle that oncogenic Wnt signalling could be specifically targeted remains controversial. Here we examine the requirement of BCL9/9l, constituents of the Wnt-enhanceosome, for intestinal transformation following loss of the tumour suppressor APC.

Intestinal Stem Cell Dynamics: A Story of Mice and Humans.

Stem cell dynamics define the probability of accumulating mutations within the intestinal epithelium. In this issue of Cell Stem Cell, Nicholson et al. (2018) report that human intestinal stem cell dynamics differ significantly from those of mice and establish that oncogenic mutations are more likely to expand; therefore, "normal" epithelium may carry multiple mutations.

Wnt ligands influence tumour initiation by controlling the number of intestinal stem cells.

Many epithelial stem cell populations follow a pattern of stochastic stem cell divisions called 'neutral drift'. It is hypothesised that neutral competition between stem cells protects against the acquisition of deleterious mutations. Here we use a Porcupine inhibitor to reduce Wnt secretion at a dose where intestinal homoeostasis is maintained despite a reduction of Lgr5+ stem cells.

TGFβ pathway limits dedifferentiation following WNT and MAPK pathway activation to suppress intestinal tumourigenesis.

Recent studies have suggested increased plasticity of differentiated cells within the intestine to act both as intestinal stem cells (ISCs) and tumour-initiating cells. However, little is known of the processes that regulate this plasticity. Our previous work has shown that activating mutations of Kras or the NF-κB pathway can drive dedifferentiation of intestinal cells lacking Apc.

HUWE1 is a critical colonic tumour suppressor gene that prevents MYC signalling, DNA damage accumulation and tumour initiation.

Cancer genome sequencing projects have identified hundreds of genetic alterations, often at low frequencies, raising questions as to their functional relevance. One exemplar gene is HUWE1, which has been found to be mutated in numerous studies. However, due to the large size of this gene and a lack of functional analysis of identified mutations, their significance to carcinogenesis is unclear.

Evidence for age-related and individual-specific changes in DNA methylation profile of mononuclear cells during early immune development in humans.

Environment induced epigenetic effects on gene expression in early life are likely to play important roles in mediating the risk of several immune-related diseases. In order to investigate this fully, it is essential to first document temporal changes in epigenetic profile in disease-free individuals as a prelude to defining environmentally mediated changes. Mononuclear cells (MC) were collected longitudinally from a small number of females at birth, 1 year, 2.

The effects of Mycobacteria vaccae derivative on allergen-specific responses in children with atopic dermatitis.

The capacity of microbial products to inhibit allergic inflammation make them logical candidates for novel therapies in allergic diseases such as atopic dermatitis. To assess the effects of intradermal Mycobacterium vaccae derivative on allergen-specific immune responses in children with moderate to severe atopic dermatitis. Peripheral blood mononuclear cells were isolated from children aged 5-16 years who received intradermal injections of M.

Differences in innate immune function between allergic and nonallergic children: new insights into immune ontogeny.

Background: Microbial products are of central interest in the modulation of allergic propensity.

Objective: We sought to explore whether allergic children show differences in microbial Toll-like receptor (TLR)-mediated responses over their first 5 years of life.

Methods: Mononuclear cells isolated from 35 allergic and 35 nonallergic children at birth and 1, 2.

Progress in understanding postnatal immune dysregulation in allergic disease.

It is increasingly unlikely that allergic disease is the result of isolated immune defects, but rather the result of altered gene activation patterns in intricate immune networks. This appears to be driven by complex environmental changes, including microbial exposure, diet, and pollutants, which are known to modify immune development in early life, beginning in pregnancy. The first models showing possible epigenetic mechanisms for these effects are beginning to emerge.

Thymic indoleamine 2,3-dioxygenase-positive eosinophils in young children: potential role in maturation of the naive immune system.

Eosinophils expressing indoleamine 2, 3-dioxygenase (IDO) may contribute to T-helper cell (Th)2 predominance. To characterize human thymus IDO+ eosinophil ontogeny relative to Th2 regulatory gene expression, we processed surgically obtained thymi from 22 children (age: 7 days to 12 years) for immunohistochemistry and molecular analysis, and measured cytokine and kynurenine levels in tissue homogenates. Luna+ eosinophils ( approximately 2% of total thymic cells) decreased in number with age (P = 0.

Algorithmic models to predict allergic disease using multiple neonatal markers.

Childhood blindness and visual impairment are as important and perhaps more devastating and disabling than adult onset blindness, because of the long span of life still remaining to be lived. Refractive errors and more particularly myopia, place a substantial burden on the individual and society. School-age children constitute a particularly vulnerable group where uncorrected refractive errors may have a dramatic impact on learning capability and educational potential.

Early experience with the TriMed fragment-specific fracture fixation system in intraarticular distal radius fractures.

This paper reports the results of fixation of intraarticular fractures of the distal radius using the TriMed fragment-specific fixation system by surgeons early in their experience with the system. A consecutive series of 22 AO types C2 and C3 fractures in 21 patients were internally fixed with the system. Restoration of articular congruity to less than 2 mm was possible in 20 fractures.

Silyamandin, a new flavonolignan isolated from milk thistle tinctures.

Our investigations into the stability of tincture preparations of milk thistle fruit [ Silybum marianum L. Gaertn. (Asteraceae)] have led to the characterization of a new flavonolignan 4-(4-hydroxy-3-methoxyphenyl)-7-[(2 R,3 R)-3,5,7-trihydroxy-4-oxochroman-2-yl]-1-oxo-1,3,3a,4,5,7a-hexahydro-2-benzofuran-5-carboxylic acid called silyamandin (1).

Induction of class II major histocompatibility antigens on thyroid, adult pancreatic islet, and fetal proislet allografts.

Cultured BALB/c (H-2d) thyroid, adult pancreatic islet and fetal proislet tissues can be accepted permanently in CBA/H (H-2k) recipients until rejection is triggered by the transfer of antidonor strain activated immune T cells. Class II MHC antigens are not expressed on the accepted grafts and are induced following immune cell transfer, but expression is quantitatively and qualitatively different for the different tissues. Thyroid allografts show intense class II MHC antigen expression early after immune cell transfer and before extensive tissue destruction has occurred.