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Christopher S Potten - One of the best experts on this subject based on the ideXlab platform.
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the stem cells of small Intestinal Crypts where are they
Cell Proliferation, 2009Co-Authors: Christopher S Potten, Markus Loeffler, R Gandara, Y R Mahida, N A WrightAbstract:Recently, there has been resurgence of interest in the question of small Intestinal stem cells, their precise location and numbers in the Crypts. In this article, we attempt to re-assess the data, including historical information often omitted in recent studies on the subject. The conclusion we draw is that the evidence supports the concept that active murine small Intestinal stem cells in steady state are few in number and are proliferative. There are two evolving, but divergent views on their location (which may be more related to scope of capability and reversibility than to location) several lineage labelling and stem cell self-renewing studies (based on Lgr5 expression) suggest a location intercalated between the Paneth cells (crypt base columnar cells (CBCCs)), or classical cell kinetic, label-retention and radiobiological evidence plus other recent studies, pointing to a location four cell positions luminally from the base of the crypt The latter is supported by recent lineage labelling of Bmi-1-expressing cells and by studies on expression of Wip-1 phosphatase. The situation in the human small intestine remains unclear, but recent mtDNA mutation studies suggest that the stem cells in humans are also located above the Paneth cell zone. There could be a distinct and as yet undiscovered relationship between these observed traits, with stem cell properties both in cells of the crypt base and those at cell position 4.
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regeneration in epithelial proliferative units as exemplified by small Intestinal Crypts
Ciba Foundation Symposium 160 - Regeneration of Vertebrate Sensory Receptor Cells, 2007Co-Authors: Christopher S PottenAbstract:Surface epithelia are subdivided structurally into a series of partially autonomous proliferative units. Within each unit the proliferative cells are organized into a lineage or hierarchy each with relatively few ancestral (stem) cells. This structural organization is strikingly illustrated by the gastroIntestinal mucosa where the proliferative cells are packaged into Crypts. In the mouse small intestine there are 250 cells in total per crypt of which about 150-160 are proliferative. The latter cells are arranged as a series of about 10 rings each of about 16 cells, starting at about the 4th position from the bottom of the crypt and running up to the 13th-14th cell position. The stem cells are believed to be located in the lowermost ring. We have been studying the regenerative process in mouse small Intestinal Crypts after various levels of injury. Exposure to small doses of cytotoxic agents (e.g. gamma-radiation) reveals that some cells in the stem cell zone are very sensitive but that apparently unaffected cells in the zone are easily disturbed in their cell cycle characteristics by this minor damage. Such observations suggest that some of the controls on stem cell proliferation are extremely local in their action. The stem cells can detect the death of one of their members and the remainder respond accordingly. After more severe injury (drugs or higher doses of radiation) the first detectable changes also appear in the stem cell zone. It is concluded that the crucial cells in the regeneration process in epithelia are the stem cells. The cell kinetic properties during regeneration have been studied experimentally and modelled mathematically.
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altered stem cell regeneration in irradiated Intestinal Crypts of senescent mice
Journal of Cell Science, 1998Co-Authors: Kareen Martin, Christopher S Potten, Stephen A Roberts, Thomas B L KirkwoodAbstract:Ageing is associated with a progressive deterioration in the functions of many organs within the body. In tissue with high cell turnover, the maintenance of the stem cells is of particular importance. Any accumulation of damage in stem cells may affect their function and hence threaten the homeostasis and regenerative capacity of the tissue. The small intestine represents a good model for the study of stem cells because of its spatial and hierarchical organisation. We have examined the effect of age on stem cell regenerative capacity after irradiation, using the microcolony assay. Crypt survival levels, the growth rate of surviving Crypts, and the number of cells able to repopulate a crypt have been investigated by irradiating groups of 6-7 month old and 28-30 month old ICRFa male mice. After high doses of irradiation, the surviving Crypts in old mice were both smaller and fewer in number than in young mice. The growth rate of surviving Crypts was determined by measuring the crypt area and the number of cells/crypt at various times after 14 Gy irradiation. There was a growth delay of between about one half and one day in the older mice. Surprisingly, the number of clonogenic cells per crypt was estimated to be greater in the older mice. These studies indicate important age-related alterations in the capacity to regenerate the Crypts after radiation damage.
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age changes in stem cells of murine small Intestinal Crypts
Experimental Cell Research, 1998Co-Authors: Kareen Martin, Thomas B L Kirkwood, Christopher S PottenAbstract:Abstract Cell senescence is seen in many types of differentiated cells but age changes in stem cells have not previously been clearly demonstrated. Changes in stem cells may be of great importance for the ageing process, because any decline with age in the numbers and functional integrity of stem cells can lead to progressive deterioration of function and of proliferative homeostasis in tissues. Stem cells of the murine small intestine provide an excellent model system because these cells occupy a well-defined position near the base of the Crypts of Lieberkuhn. We examined mice aged between 5 and 32 months and found age-related alterations in the histology of the small intestine and in the apoptotic response of stem cells to low-dose irradiation. Apoptosis in the Crypts is concentrated around the stem cell position and can be markedly elevated by exposure to radiation or cytotoxic agents, suggesting that “suicide” of damaged stem cells may be an important system for long-term tissue maintenance. Animals aged 5, 15, 18, and 29 months were exposed to either 1 or 8 Gy gamma irradiation. A twofold increase in the level of apoptosis was seen following 1 Gy gamma irradiation in the 29-month-old animals, compared to the young and middle-age groups. After 8 Gy irradiation the level of apoptosis in all age groups was high and the age effect less pronounced. The data suggest that stem cells do undergo some functional alteration with age.
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clonality and life cycles of Intestinal Crypts explained by a state dependent stochastic model of epithelial stem cell organization
Journal of Theoretical Biology, 1997Co-Authors: Markus Loeffler, T Bratke, U Paulus, Christopher S PottenAbstract:Abstract The organization and control of stem cells is a key issue in epithelial cell biology. The small Intestinal murine crypt is a useful tissue to study such problems since stem cells are known to be located at specific positions at the bottom of the crypt where they are self maintaining. Recent data suggest, that (1) the number of active stem cells in a crypt can fluctuate, (2) the immediate progeny of a single stem cell can replace other stem cells eventually leading to monoclonality and (3) the life cycle of Crypts may be linked to stem cell dynamics. It is the objective of this paper to suggest a stochastic state-dependent model of stem cell and crypt growth which can explain and link these phenomena into one comprehensive framework. Monte Carlo simulations are performed to show consistency with available data. The model explains the size distribution of small Intestinal Crypts in steady state, the observations of stem cell fluctuations and monoclonality conversion, recovery of the crypt population after moderate damage and the rate of crypt fission and extinction. The key assumption of this model is an autoregulatory control of stem cell growth.
N A Wright - One of the best experts on this subject based on the ideXlab platform.
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the stem cells of small Intestinal Crypts where are they
Cell Proliferation, 2009Co-Authors: Christopher S Potten, Markus Loeffler, R Gandara, Y R Mahida, N A WrightAbstract:Recently, there has been resurgence of interest in the question of small Intestinal stem cells, their precise location and numbers in the Crypts. In this article, we attempt to re-assess the data, including historical information often omitted in recent studies on the subject. The conclusion we draw is that the evidence supports the concept that active murine small Intestinal stem cells in steady state are few in number and are proliferative. There are two evolving, but divergent views on their location (which may be more related to scope of capability and reversibility than to location) several lineage labelling and stem cell self-renewing studies (based on Lgr5 expression) suggest a location intercalated between the Paneth cells (crypt base columnar cells (CBCCs)), or classical cell kinetic, label-retention and radiobiological evidence plus other recent studies, pointing to a location four cell positions luminally from the base of the crypt The latter is supported by recent lineage labelling of Bmi-1-expressing cells and by studies on expression of Wip-1 phosphatase. The situation in the human small intestine remains unclear, but recent mtDNA mutation studies suggest that the stem cells in humans are also located above the Paneth cell zone. There could be a distinct and as yet undiscovered relationship between these observed traits, with stem cell properties both in cells of the crypt base and those at cell position 4.
Hans Clevers - One of the best experts on this subject based on the ideXlab platform.
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the r spondin lgr5 rnf43 module regulator of wnt signal strength
Genes & Development, 2014Co-Authors: Wim De Lau, Weng Chuan Peng, Piet Gros, Hans CleversAbstract:Lgr5 was originally discovered as a common Wnt target gene in adult Intestinal Crypts and colon cancer. It was subsequently identified as an exquisite marker of multiple Wnt-driven adult stem cell types. Lgr5 and its homologs, Lgr4 and Lgr6, constitute the receptors for R-spondins, potent Wnt signal enhancers and stem cell growth factors. The Lgr5/R-spondin complex acts by neutralizing Rnf43 and Znrf3, two transmembrane E3 ligases that remove Wnt receptors from the stem cell surface. Rnf43/Znrf3 are themselves encoded by Wnt target genes and constitute a negative Wnt feedback loop. Thus, adult stem cells are controlled by an intricate interplay of potent Wnt agonists, antagonists, and anti-antagonists.
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occult progression by apc deficient Intestinal Crypts as a target for chemoprevention
Carcinogenesis, 2014Co-Authors: Hans Clevers, Jared M Fischer, Darryl Shibata, Michael R Liskay, Arnout G SchepersAbstract:Although Apc mutation is widely considered an initiating event in colorectal cancer, little is known about the earliest stages of tumorigenesis following sporadic Apc loss. Therefore, we have utilized a novel mouse model that facilitates the sporadic inactivation of Apc via frameshift reversion of Cre in single, isolated cells and subsequently tracks the fates of Apc-deficient Intestinal cells. Our results suggest that consistent with Apc being a 'gatekeeper', loss of Apc early in life during Intestinal growth leads to adenomas or increased crypt fission, manifested by fields of mutant but otherwise normal-appearing Crypts. In contrast, Apc loss occurring later in life has minimal consequences, with mutant Crypts being less prone to either increased crypt fission or adenoma formation. Using the stem cell-specific Lgr5-CreER mouse, we generated different sized fields of Apc-deficient Crypts via independent recombination events and found that field size correlates with progression to adenoma. To evaluate this early stage prior to adenoma formation as a therapeutic target, we examined the chemopreventive effects of sulindac on Apc-deficient occult crypt fission. We found that sulindac treatment started early in life inhibits the morphologically occult spread of Apc-deficient Crypts and thus reduces adenoma numbers. Taken together these results suggest that: (i) earlier Apc loss promotes increased crypt fission, (ii) a field of Apc-deficient Crypts, which can form via occult crypt fission or independent neighboring events, is an important intermediate between loss of Apc and adenoma formation and (iii) normal-appearing Apc-deficient Crypts are potential unappreciated targets for cancer screening and chemoprevention.
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paneth cells maestros of the small Intestinal Crypts
Annual Review of Physiology, 2013Co-Authors: Hans Clevers, Charles L. BevinsAbstract:Paneth cells are highly specialized epithelial cells of the small intestine, where they coordinate many physiological functions. First identified more than a century ago on the basis of their readily discernible secretory granules by routine histology, these cells are located at the base of the Crypts of Lieberkuhn, tiny invaginations that line the mucosal surface all along the small intestine. Investigations over the past several decades determined that these cells synthesize and secrete substantial quantities of antimicrobial peptides and proteins. More recent studies have determined that these antimicrobial molecules are key mediators of host-microbe interactions, including homeostatic balance with colonizing microbiota and innate immune protection from enteric pathogens. Perhaps more intriguing, Paneth cells secrete factors that help sustain and modulate the epithelial stem and progenitor cells that cohabitate in the Crypts and rejuvenate the small Intestinal epithelium. Dysfunction of Paneth cell biology contributes to the pathogenesis of chronic inflammatory bowel disease.
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Optimality in the Development of Intestinal Crypts
Cell, 2012Co-Authors: Shalev Itzkovitz, Irene C. Blat, Tyler Jacks, Hans Clevers, Alexander Van OudenaardenAbstract:SUMMARY Intestinal Crypts in mammals are comprised of longlived stem cells and shorter-lived progenies. These two populations are maintained in specific proportionsduringadultlife.Here,weinvestigatethedesign principles governing the dynamics of these proportions during crypt morphogenesis. Using optimal control theory, we show that a proliferation strategy known as a ‘‘bang-bang’’ control minimizes the time to obtain a mature crypt. This strategy consists of a surge of symmetric stem cell divisions, establishing the entire stem cell pool first, followed by a sharp transition to strictly asymmetric stem cell divisions, producing nonstem cells with a delay. We validate these predictions using lineage tracing and single-molecule fluorescence in situ hybridization of Intestinal Crypts in infant mice, uncovering small Crypts that are entirely composed of Lgr5-labeled stem cells, which become a minority as Crypts continue to grow. Our approach can be used to uncover similar design principles in other developmental systems.
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cdx2 determines the fate of postnatal Intestinal endoderm
Development, 2012Co-Authors: Emma J Stringer, Hans Clevers, Toshiro Sato, Nick Barker, Isabelle Duluc, Thoueiba Saandi, Irwin Davidson, Monika Bialecka, Catrin Pritchard, Doug J WintonAbstract:Knock out of Intestinal Cdx2 produces different effects depending upon the developmental stage at which this occurs. Early in development it produces histologically ordered stomach mucosa in the midgut. Conditional inactivation of Cdx2 in adult Intestinal epithelium, as well as specifically in the Lgr5-positive stem cells, of adult mice allows long-term survival of the animals but fails to produce this phenotype. Instead, the endodermal cells exhibit cell-autonomous expression of gastric genes in an Intestinal setting that is not accompanied by mesodermal expression of Barx1, which is necessary for gastric morphogenesis. Cdx2-negative endodermal cells also fail to express Sox2, a marker of gastric morphogenesis. Maturation of the stem cell niche thus appears to be associated with loss of ability to express positional information cues that are required for normal stomach development. Cdx2-negative Intestinal Crypts produce subsurface cystic vesicles, whereas untargeted Crypts hypertrophy to later replace the surface epithelium. These observations are supported by studies involving inactivation of Cdx2 in Intestinal Crypts cultured in vitro. This abolishes their ability to form long-term growing Intestinal organoids that differentiate into Intestinal phenotypes. We conclude that expression of Cdx2 is essential for differentiation of gut stem cells into any of the Intestinal cell types, but they maintain a degree of cell-autonomous plasticity that allows them to switch on a variety of gastric genes.
Markus Loeffler - One of the best experts on this subject based on the ideXlab platform.
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the stem cells of small Intestinal Crypts where are they
Cell Proliferation, 2009Co-Authors: Christopher S Potten, Markus Loeffler, R Gandara, Y R Mahida, N A WrightAbstract:Recently, there has been resurgence of interest in the question of small Intestinal stem cells, their precise location and numbers in the Crypts. In this article, we attempt to re-assess the data, including historical information often omitted in recent studies on the subject. The conclusion we draw is that the evidence supports the concept that active murine small Intestinal stem cells in steady state are few in number and are proliferative. There are two evolving, but divergent views on their location (which may be more related to scope of capability and reversibility than to location) several lineage labelling and stem cell self-renewing studies (based on Lgr5 expression) suggest a location intercalated between the Paneth cells (crypt base columnar cells (CBCCs)), or classical cell kinetic, label-retention and radiobiological evidence plus other recent studies, pointing to a location four cell positions luminally from the base of the crypt The latter is supported by recent lineage labelling of Bmi-1-expressing cells and by studies on expression of Wip-1 phosphatase. The situation in the human small intestine remains unclear, but recent mtDNA mutation studies suggest that the stem cells in humans are also located above the Paneth cell zone. There could be a distinct and as yet undiscovered relationship between these observed traits, with stem cell properties both in cells of the crypt base and those at cell position 4.
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clonality and life cycles of Intestinal Crypts explained by a state dependent stochastic model of epithelial stem cell organization
Journal of Theoretical Biology, 1997Co-Authors: Markus Loeffler, T Bratke, U Paulus, Christopher S PottenAbstract:Abstract The organization and control of stem cells is a key issue in epithelial cell biology. The small Intestinal murine crypt is a useful tissue to study such problems since stem cells are known to be located at specific positions at the bottom of the crypt where they are self maintaining. Recent data suggest, that (1) the number of active stem cells in a crypt can fluctuate, (2) the immediate progeny of a single stem cell can replace other stem cells eventually leading to monoclonality and (3) the life cycle of Crypts may be linked to stem cell dynamics. It is the objective of this paper to suggest a stochastic state-dependent model of stem cell and crypt growth which can explain and link these phenomena into one comprehensive framework. Monte Carlo simulations are performed to show consistency with available data. The model explains the size distribution of small Intestinal Crypts in steady state, the observations of stem cell fluctuations and monoclonality conversion, recovery of the crypt population after moderate damage and the rate of crypt fission and extinction. The key assumption of this model is an autoregulatory control of stem cell growth.
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Somatic mutation, monoclonality and stochastic models of stem cell organization in the Intestinal crypt.
Journal of theoretical biology, 1993Co-Authors: Markus Loeffler, Douglas J Winton, Andreas Birke, Christopher S PottenAbstract:Among highly proliferating tissues the Intestinal tissue is of particular interest. Techniques are available that permit an insight into how Intestinal Crypts as the basic macroscopic tissue unit are regenerated from a small population of self-maintaining stem cells. However, neither the precise number of these stem cells nor their properties are known. We have recently suggested a model of stem cell organization which explains the life cycle of murine Intestinal Crypts, their birth (by crypt fission) and extinction rates, as well as their size distribution on a quantitative basis (Loeffler & Grossman, 1991). The model assumptions involve two stochastic branching processes, one for the growth of several independent indistinguishable stem cells and a second for a threshold dependent crypt fission process. New data have now become available challenging the above concept. They relate to the conversion of Crypts to monoclonal phenotypic expression after mutagenic events, presumably taking place in single stem cells. A detailed analysis of these data is shown here utilizing a more elaborate version of the above model. The new data are consistent with this model within the range of parameters predicted previously. We conclude that the cellular regeneration of Intestinal Crypts can be explained on the basis of several indistinguishable stem cells which can replace each other.
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a stochastic branching model with formation of subunits applied to the growth of Intestinal Crypts
Journal of Theoretical Biology, 1991Co-Authors: Markus Loeffler, Bernd GroßmannAbstract:The Intestinal epithelium is one of the most rapidly regenerating tissues in mammals. Cell production takes place in the Intestinal Crypts which contain about 250 cells. Only a minority of 1–60 proliferating cells are able to maintain a crypt over a long period of time. However, so far attempts to identify these stem cells were unsuccessful. Therefore, little is known about their cellular growth and selfmaintenance properties. On the other hand, the Crypts appear to exhibit a life cycle which starts by fission of existing Crypts and ends by fission or extinction. Data on these processes have recently become available. Here, we demonstrate how these data on the life cycle of the macroscopic crypt structure can be used to derive a quantitative model of the microscopic process of stem cell growth. The model assumptions are: (1) stem cells undergo a time independent supracritical Markovian branching process (Galton-Watson process); (2) a crypt divides if the number of stem cells exceeds a given threshold and the stem cells are distributed to both daughter Crypts according to binomial statistics; (3) the size of the crypt is proportional to the stem cell number. This model combining two different stochastic branching processes describes a new class of processes whose stationary stability and asymptotic behavior are examined. This model should be applicable to various growth processes with formation of subunits (e.g. population growth with formation of colonies in biology, ecology and sociology). Comparison with crypt data shows that Intestinal stem cells have a probability of over 0·8 of dividing asymmetrically and that the threshold number should be 8 or larger.
Johan H Van Es - One of the best experts on this subject based on the ideXlab platform.
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paneth cells constitute the niche for lgr5 stem cells in Intestinal Crypts
Nature, 2011Co-Authors: Toshiro Sato, Noah F. Shroyer, Johan H Van Es, Hugo J Snippert, Daniel E Stange, Robert G J Vries, Maaike Van Den Born, Nick Barker, Marc Van De Wetering, Hans CleversAbstract:Homeostasis of self-renewing small Intestinal Crypts results from neutral competition between Lgr5 stem cells, which are small cycling cells located at crypt bottoms. Lgr5 stem cells are interspersed between terminally differentiated Paneth cells that are known to produce bactericidal products such as lysozyme and cryptdins/defensins. Single Lgr5-expressing stem cells can be cultured to form long-lived, self-organizing crypt-villus organoids in the absence of non-epithelial niche cells. Here we find a close physical association of Lgr5 stem cells with Paneth cells in mice, both in vivo and in vitro. CD24(+) Paneth cells express EGF, TGF-α, Wnt3 and the Notch ligand Dll4, all essential signals for stem-cell maintenance in culture. Co-culturing of sorted stem cells with Paneth cells markedly improves organoid formation. This Paneth cell requirement can be substituted by a pulse of exogenous Wnt. Genetic removal of Paneth cells in vivo results in the concomitant loss of Lgr5 stem cells. In colon Crypts, CD24(+) cells residing between Lgr5 stem cells may represent the Paneth cell equivalents. We conclude that Lgr5 stem cells compete for essential niche signals provided by a specialized daughter cell, the Paneth cell.
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single lgr5 stem cells build crypt villus structures in vitro without a mesenchymal niche
Nature, 2009Co-Authors: Toshiro Sato, Johan H Van Es, Hugo J Snippert, Daniel E Stange, Robert G J Vries, Nick Barker, Marc Van De Wetering, Arie Abo, Pekka Kujala, Peter J PetersAbstract:The Intestinal epithelium is the most rapidly self-renewing tissue in adult mammals. We have recently demonstrated the presence of about six cycling Lgr5(+) stem cells at the bottoms of small-Intestinal Crypts. Here we describe the establishment of long-term culture conditions under which single Crypts undergo multiple crypt fission events, while simultanously generating villus-like epithelial domains in which all differentiated cell types are present. Single sorted Lgr5(+) stem cells can also initiate these cryptvillus organoids. Tracing experiments indicate that the Lgr5(+) stem-cell hierarchy is maintained in organoids. We conclude that Intestinal cryptvillus units are self-organizing structures, which can be built from a single stem cell in the absence of a non-epithelial cellular niche.
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notch gamma secretase inhibition turns proliferative cells in Intestinal Crypts and adenomas into goblet cells
Nature, 2005Co-Authors: Johan H Van Es, Maaike Van Den Born, Marielle E. Van Gijn, Harry Begthel, Doug J Winton, Orbicia Riccio, Marc Vooijs, Miranda Cozijnsen, Sylvie Robine, Freddy RadtkeAbstract:The self-renewing epithelium of the small intestine is ordered into stem/progenitor crypt compartments and differentiated villus compartments. Recent evidence indicates that the Wnt cascade is the dominant force in controlling cell fate along the crypt-villus axis. Here we show a rapid, massive conversion of proliferative crypt cells into post-mitotic goblet cells after conditional removal of the common Notch pathway transcription factor CSL/RBP-J. We obtained a similar phenotype by blocking the Notch cascade with a gamma-secretase inhibitor. The inhibitor also induced goblet cell differentiation in adenomas in mice carrying a mutation of the Apc tumour suppressor gene. Thus, maintenance of undifferentiated, proliferative cells in Crypts and adenomas requires the concerted activation of the Notch and Wnt cascades. Our data indicate that gamma-secretase inhibitors, developed for Alzheimer's disease, might be of therapeutic benefit in colorectal neoplastic disease.
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Wnt signalling induces maturation of Paneth cells in Intestinal Crypts
Nature cell biology, 2005Co-Authors: Johan H Van Es, Maaike Van Den Born, Philippe Jay, Alex Gregorieff, Marielle E. Van Gijn, Suzanne Jonkheer, Pantelis Hatzis, Andrea Thiele, Harry Begthel, Thomas BrabletzAbstract:Wnt signalling, which is transduced through beta-catenin/TCF4, maintains the undifferentiated state of Intestinal crypt progenitor cells. Mutational activation of the pathway initiates the adenomacarcinoma sequence. Whereas all other differentiated epithelial cells migrate from the crypt onto the villus, Paneth cells home towards the source of Wnt signals--that is, the crypt bottom. Here, we show that expression of a Paneth gene programme is critically dependent on TCF4 in embryonic intestine. Moreover, conditional deletion of the Wnt receptor Frizzled-5 abrogates expression of these genes in Paneth cells in the adult intestine. Conversely, adenomas in Apc-mutant mice and colorectal cancers in humans inappropriately express these Paneth-cell genes. These observations imply that Wnt signals in the crypt can separately drive a stem-cell/progenitor gene programme and a Paneth-cell maturation programme. In Intestinal cancer, both gene programmes are activated simultaneously.
