Intestinal Progenitor Cells Research Articles

Vasoactive intestinal peptide promotes secretory differentiation and mitigates radiation-induced intestinal injury

BackgroundVasoactive intestinal peptide (VIP) is a neuronal peptide with prominent distribution along the enteric nervous system. While effects of VIP on intestinal motility, mucosal vasodilation, secretion, and mucosal immune cell function are well-studied, the direct impact of VIP on intestinal epithelial cell turnover and differentiation remains less understood. Intestinal stem and progenitor cells are essential for the maintenance of intestinal homeostasis and regeneration, and their functions can be modulated by factors of the stem cell niche, including neuronal mediators. Here, we investigated the role of VIP in regulating intestinal epithelial homeostasis and regeneration following irradiation-induced injury.MethodsJejunal organoids were derived from male and female C57Bl6/J, Lgr5-EGFP-IRES-CreERT2 or Lgr5-EGFP-IRES-CreERT2/R26R-LSL-TdTomato mice and treated with VIP prior to analysis. Injury conditions were induced by exposing organoids to 6 Gy of irradiation (IR). To investigate protective effects of VIP in vivo, mice received 12 Gy of abdominal IR followed by intraperitoneal injections of VIP.ResultsWe observed that VIP promotes epithelial differentiation towards a secretory phenotype predominantly via the p38 MAPK pathway. Moreover, VIP prominently modulated epithelial proliferation as well as the number and proliferative activity of Lgr5-EGFP+ progenitor cells under homeostatic conditions. In the context of acute irradiation injury in vitro, we observed that IR injury renders Lgr5-EGFP+ progenitor cells more susceptible to VIP-induced modulations, which coincided with the strong promotion of epithelial regeneration by VIP. Finally, the observed effects translate into an in vivo model of abdominal irradiation, where VIP showed to prominently mitigate radiation-induced injury.ConclusionsVIP prominently governs intestinal homeostasis by regulating epithelial progenitor cell proliferation and differentiation and promotes intestinal regeneration following acute irradiation injury.

Inonotus obliquus aqueous extract inhibits intestinal inflammation and insulin metabolism defects in Drosophila

In biomedical research, the fruit fly (Drosophila melanogaster) is among the most effective and flexible model organisms. Through the use of the Drosophila model, molecular mechanisms of human diseases can be investigated and candidate pharmaceuticals can be screened. White rot fungus Inonotus obliquus is a member of the family Hymenochaetaceae. Due to its multifaceted pharmacological effects, this fungus has been the subject of scientific investigation. Nevertheless, the precise mechanisms by which Inonotus obliquus treats diseases remain unclear. In this study, we prepared an aqueous extract derived from Inonotus obliquus and demonstrated that it effectively prevented the negative impacts of inflammatory agents on flies, including overproliferation and overdifferentiation of intestinal progenitor cells and decreased survival rate. Furthermore, elevated reactive oxygen species levels and cell death were alleviated by Inonotus obliquus aqueous extract, suggesting that this extract inhibited intestinal inflammation. Additionally, Inonotus obliquus aqueous extract had an impact on the insulin pathway, as it alleviated growth defects in flies that were fed a high-sugar diet and in chico mutants. In addition, we determined the composition of Inonotus obliquus aqueous extract and conducted a network pharmacology analysis in order to identify prospective key compounds and targets. In brief, Inonotus obliquus aqueous extract exhibited considerable potential as a therapeutic intervention for human diseases. Our research has established a foundational framework that supports the potential clinical implementation of Inonotus obliquus.

Cell-fate conversion of intestinal cells in adult Drosophila midgut by depleting a single transcription factor

The manipulation of cell identity by reprograming holds immense potential in regenerative medicine, but is often limited by the inefficient acquisition of fully functional cells. This problem can potentially be resolved by better understanding the reprogramming process using in vivo genetic models, which are currently scarce. Here we report that both enterocytes (ECs) and enteroendocrine cells (EEs) in adult Drosophila midgut show a surprising degree of cell plasticity. Depleting the transcription factor Tramtrack in the differentiated ECs can initiate Prospero-mediated cell transdifferentiation, leading to EE-like cells. On the other hand, depletion of Prospero in the differentiated EEs can lead to the loss of EE-specific transcription programs and the gain of intestinal progenitor cell identity, allowing cell cycle re-entry or differentiation into ECs. We find that intestinal progenitor cells, ECs, and EEs have a similar chromatin accessibility profile, supporting the concept that cell plasticity is enabled by pre-existing chromatin accessibility with switchable transcription programs. Further genetic analysis with this system reveals that the NuRD chromatin remodeling complex, cell lineage confliction, and age act as barriers to EC-to-EE transdifferentiation. The establishment of this genetically tractable in vivo model should facilitate mechanistic investigation of cell plasticity at the molecular and genetic level.

Gastric adenocarcinoma with intestinal progenitor cell differentiation: a morphologically underdiagnosed and more invasive distinctive type of gastric adenocarcinoma.

This study aims to explore the clinical and pathological characteristics, prognosis, diagnosis, and differential diagnosis of gastric adenocarcinoma with enteroblastic differentiation (GAED) in elderly patients. A total of 16 cases of GAED diagnosed from August 2019 to August 2022 at the First Affiliated Hospital of Nanchang University were retrospectively collected to analyze their clinical and pathological features. A control group of 360 cases of conventional gastric adenocarcinoma diagnosed during the same period was used for comparison. Among the 16 GAED patients, 11 were male and 5 were female, with ages ranging from 64 to 89 years (median age 75.5 years). Clinical manifestations of these patients included symptoms such as abdominal pain, bloating, hematemesis, and melena. The macroscopic classification revealed 11 cases of ulcerative lesions, 4 protruded lesions, and 1 diffusely infiltrative lesion. Tumor sizes varied from 3 to 9.5 cm in diameter, with a median diameter of 4.75 cm. Microscopically, the tumor cells exhibited tubular, papillary, and cribriform arrangements, with cuboidal or columnar morphology, relatively distinct cell boundaries, and cytoplasm that appeared clear or weakly acidophilic. Immunophenotyping analysis revealed the expression of SALL4 (15/16), Glypican-3 (12/16), CDX2 (12/16), CD10 (10/16), and p53 (12 cases exhibiting mutant expression, 4 cases exhibiting wild-type expression) within the tumor cells. There was no loss of mismatch repair proteins (MLH1, PMS2, MSH2, MSH6). The Ki-67 proliferation index ranged from 50% to 95%. In comparison to conventional gastric adenocarcinoma, GAED was frequently found in the gastric antrum (P<0.001) and exhibited a higher incidence of intravascular cancer emboli (P<0.001). Significant differences were noted in the Lauren classification, invasion depth, differentiation degree (P<0.01), and macroscopic type (P<0.05). However, no significant differences were found regarding age, gender, tumor diameter, neural invasion, or lymph node metastasis (P>0.05). The postoperative follow-up ranging from 5 to 29 months revealed one death and 15 cases of disease-free survival. GAED is a special subtype of gastric adenocarcinoma characterized by a combination of embryonal and intestinal differentiation immunophenotypes, as well as its increased propensity for biological invasion. Accurate identification of GAED is crucial in pathological practice, as it helps differentiate between GAED and conventional adenocarcinoma and aids in the evaluation of tumor malignancy. Furthermore, it is imperative to conduct a differential diagnosis that involves hepatoid adenocarcinoma, yolk sac tumor-like adenocarcinoma, and metastatic hepatocellular carcinoma.

RAB11A and RAB11B control mitotic spindle function in intestinal epithelial progenitor cells.

RAB11 small GTPases and associated recycling endosome have been localized to mitotic spindles and implicated in regulating mitosis. However, the physiological significance of such regulation has not been observed in mammalian tissues. We have used newly engineered mouse models to investigate intestinal epithelial renewal in the absence of single or double isoforms of RAB11 family members: Rab11a and Rab11b. Comparing with single knockouts, mice with compound ablation demonstrate a defective cell cycle entry and robust mitotic arrest followed by apoptosis, leading to a total penetrance of lethality within 3 days of gene ablation. Upon Rab11 deletion ex vivo, enteroids show abnormal mitotic spindle formation and cell death. Untargeted proteomic profiling of Rab11a and Rab11b immunoprecipitates has uncovered a shared interactome containing mitotic spindle microtubule regulators. Disrupting Rab11 alters kinesin motor KIF11 function and impairs bipolar spindle formation and cell division. These data demonstrate that RAB11A and RAB11B redundantly control mitotic spindle function and intestinal progenitor cell division, a mechanism that may be utilized to govern the homeostasis and renewal of other mammalian tissues.

Lrig1+ small intestinal progenitor cells require MYO5B for proper crypt proliferation and enterocyte maturation

Microvillus inclusion disease (MVID) is a congenital disorder characterized by severe diarrhea. MVID is caused by inactivating mutations in myosin Vb (MYO5B), a motor protein. Mice lacking MYO5B in their intestinal epithelium have demonstrated the importance of MYO5B in enterocyte brush border formation and epithelial cell differentiation. Additionally, the proliferative zone of the intestinal crypt of MYO5B-deficient mice is elongated compared to controls. We hypothesize that the progenitor cell-specific Cre driver under Lrig1 demonstrates crypt-specific effects caused by MYO5B loss. Lrig1-CreERT2;R26R-YFP and Myo5bfl/fl mice were crossbred to generate Lrig1-CreERT2;R26R-YFP;MYO5B fl/fl (Lrig1 ΔMYO5B ) mice. Adult Lrig1 ΔMYO5B mice and control littermates received tamoxifen injection at day 0. GI tissues were collected 2.5, 3, 4, and 5 days after tamoxifen administration for histological characterization. Lrig1 ΔMYO5B mice began experiencing significant weight loss 4 days after tamoxifen injection and lost 20% of their starting body weight on day 5. At day 5, the Lrig1 ΔMYO5B mouse colon was devoid of solid feces and their small intestine contained clear luminal contents, together suggesting a watery diarrheal phenotype. Enterocytes of Lrig1DMYO5B mice on day 5 contained abnormal cytoplasmic accumulation of PAS staining. Fewer goblet cells were apparent in intestinal sections from day 3 and 5 Lrig1 ΔMYO5B mice compared to controls. Crypts were elongated starting at day 3. Similarly, the PCNA+ epithelial region was expanded in Lrig1 ΔMYO5B mice, even reaching into the villi at day 5. The time course of the PCNA+ region expansion corresponded to the wave of MYO5B-loss beginning at the base of crypts. MYO5B expression was diminished in the crypts at day 3 and nearly absent from the epithelium by day 5. Interestingly, expression of 3-hydroxy-3-methylglutaryl-CoA synthase 2 (HMGCS2), the rate-limited enzyme of ketogenesis that is important for stem cell function, was expanded in the crypt at day 3 and 5 after tamoxifen. Sodium/glucose cotransporter 1 (SGLT1), which is present along the apical surface of mature enterocytes, was progressively diminished and mis-localized away from the apical surface after tamoxifen administration. Apical sodium-dependent bile acid transporter (ASBT), found in the distal small intestine, demonstrated a similar mis-localization away from the apical membrane in enterocytes.We established a novel mouse model that demonstrates progressive MYO5B loss in the intestinal epithelium, starting at the base of the crypt and reaching villi tips over the course of 5 days following Cre induction. This Lrig1 ΔMYO5B strain will allow for lineage tracing studies to better understand the effect of MYO5B loss on intestinal epithelial differentiation and progenitor function. NSF GFRP, NIH R01DK128190 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

SIRT1 Controls Enteroendocrine Progenitor Cell Proliferation in High-Fat Diet-Fed Mice

We aimed to investigate how sirtuin 1 (SIRT1), a conserved mammalian Nicotinamide adenine dinucleotide+-dependent protein deacetylase, regulates the number of enteroendocrine cells (EECs). EECs benefit metabolism, and their increase potentially could treat type 2 diabetes and obesity. We used mice with specific Sirt1 disruption in the intestinal epithelium (VilKO, villin-Cre+, and Sirt1flox/flox mice) or enteroendocrine progenitor cells (EEPCs) (NgnKO, neurogenin 3-Cre+, Sirt1flox/flox mice) and mice with increased SIRT1 activity owing to overexpression (Sir2d mice) or 24-hour fasting. Mice were fed a high-fat diet (HFD), and blood glucagon-like peptide 1 (GLP-1) and glucose levels were measured. Intestinal tissues, EECs, andformed organoids were analyzed using quantitative polymerase chain reaction, immunoblotting, and immunohistochemistry. In HFD-fed VilKO and NgnKO mice, an increase in EECs (42.3% and 37.2%), GLP-1- or GLP-2-producing L cells (93.0% and 61.4%), and GLP-1 (85.7% and 109.6%) was observed after glucose loading, explaining the improved metabolic phenotype of HFD-VilKO mice. These increases were associated with up-regulated expression of neurogenin 3 (EEPC marker) in crypts of HFD-VilKO and HFD-NgnKO mice, respectively. Conversely, Sir2d or 24-hour fasted mice showed a decrease in EECs (21.6%), L cells (41.6%), and proliferative progenitor cells. SIRT1 overexpression- or knockdown-mediated change in the progenitor cell proliferation was associated with Wnt/β-catenin activity changes. Notably, Wnt/β-catenin inhibitor completely suppressed EEC and L-cell increases in HFD-VilKO mice or organoids from HFD-VilKO and HFD-NgnKO mice. Intestinal SIRT1 in EECs modulates the EEPC cycle by regulating β-catenin activity and can control the number of EECs in HFD-fed mice, which is a previously unknown role.

The RNA-binding protein Swm is critical for Drosophila melanogaster intestinal progenitor cell maintenance.

The regulation of stem cell survival, self-renewal, and differentiation is critical for the maintenance of tissue homeostasis. Although the involvement of signaling pathways and transcriptional control mechanisms in stem cell regulation have been extensively investigated, the role of post-transcriptional control is still poorly understood. Here, we show that the nuclear activity of the RNA-binding protein Second Mitotic Wave Missing is critical for Drosophila melanogaster intestinal stem cells and their daughter cells, enteroblasts, to maintain their progenitor cell properties and functions. Loss of swm causes intestinal stem cells and enteroblasts to stop dividing and instead detach from the basement membrane, resulting in severe progenitor cell loss. swm loss is further characterized by nuclear accumulation of poly(A)+ RNA in progenitor cells. Second Mitotic Wave Missing associates with transcripts involved in epithelial cell maintenance and adhesion, and the loss of swm, while not generally affecting the levels of these Second Mitotic Wave Missing-bound mRNAs, leads to elevated expression of proteins encoded by some of them, including the fly ortholog of Filamin. Taken together, this study indicates a nuclear role for Second Mitotic Wave Missing in adult stem cell maintenance, raising the possibility that nuclear post-transcriptional regulation of mRNAs encoding cell adhesion proteins ensures proper attachment of progenitor cells.

Apelin drives endothelial cell migration toward intestinal progenitor cells.

Apelin drives endothelial cell migration toward intestinal progenitor cells.

Functional MYO5B Loss Alters Lipid Metabolic Pathways in Intestinal Progenitor Cells

Background and Aims: Differentiation of intestinal epithelial cells involves cell division inhibition, cell lineage choice, and brush border elaboration. Myosin Vb (MYO5B) is a motor protein that is critical for cell polarization and membrane protein trafficking in intestinal epithelial cells and its deficiency causes both hyperproliferation and microvillus defects. Recently, we reported that a bioactive phospholipid, lysophosphatidic acid (LPA), can promote cell differentiation and nutrient absorption in tamoxifen‐induced MYO5B knockout mice in vivo and in enteroids. Our RNA‐sequencing data with KEGG pathway and GO enrichment analysis indicated that MYO5B loss disrupts stem cell characteristics, cell lineage differentiation, and energy metabolic pathways. We hypothesize that the alteration of metabolic pathways in progenitor cells causes the disruption of stem cell function.Methods: Adult Villin‐CreERT2;Myo5bflox/flox or littermate control (Myo5bflox/flox) mice received a single dose of tamoxifen and the intestinal tissues were analyzed 4 days after the tamoxifen injection. Fresh frozen sections of jejunum were analyzed by imaging mass spectrometry (IMS). Immunostaining for key metabolic enzymes were utilized to support the RNA‐seq and IMS observations.Results: Using RNA‐sequencing, MYO5B deficient epithelial cells showed significant decreases in transcripts for enzymes that mediate fatty acid ß‐oxidation compared to control mouse jejunum. Instead, Acsl3, Acat2, and Hmgcs2 were significantly upregulated, proteins that are important for lipogenesis, cholesterol ester synthesis, and ketogenesis, respectively. Consistent with these results, IMS demonstrated that MYO5B deficient tissues accumulated long‐chain fatty acids, phosphatidylinositol, cholesterol derivatives, and nucleotide products in the mucosa (Figure 1). Immunostaining signals of HMGCS2 in control mouse jejunum is limited to the crypt stem cells, whereas MYO5B‐deficient intestine showed expanded HMGCS2 expression in the proliferative cell zone. Interestingly, systemic LPA treatment in MYO5B‐deficient mice further increased the expression of HMGCS2 in both proliferating and differentiated epithelial cells (Figure 2). These observations suggest that MYO5B loss induces a starvation‐like phenotype in proliferative epithelial cells and that LPA treatment increased ketone body production as alternative energy fuels, resulting in the promotion of epithelial cell differentiation.Conclusion: MYO5B loss impairs fatty acid oxidation in the intestinal progenitor cells, which likely leads to cell differentiation deficits. Alteration of metabolic pathways might be a therapeutic target for epithelial disfunction seen in diarrheal diseases.

Interplay between intestinal microbiota and PRDM16‐mediated metabolic regulation of intestinal stem and progenitor cells

Distinct metabolic programs regulate intestinal stem cell renewal and differentiation. However, the mechanisms that rewire metabolism during differentiation are poorly defined. Previously, we have shown that the transcription factor PRDM16 is a critical regulator of intestinal metabolism and differentiation. Acute deletion of Prdm16 in adult mice causes intestinal wasting, apoptosis, and an accumulation of poorly differentiated cells in the small intestinal crypt, primarily in the duodenum and proximal jejunum. PRDM16 has emerged as a regulator of metabolic signaling in multiple tissues including thermogenic adipose tissue and the small intestine. RNA‐seq and tracer metabolomic studies show that PRDM16 regulates fatty acid oxidation (FAO) in the intestinal crypt, leading to impaired differentiation of stem and transit amplifying cells into mature cells.Our current studies have focused on the effects of the intestinal microbiota, which produces significant quantities of metabolites that could affect cells in the digestive tract. We postulated that altering the microbiome of mice in the context of Prdm16 deletion could modify the phenotype. Strikingly, pre‐treatment of animals with an antibiotic cocktail including ampicillin, neomycin, vancomycin and metronidazole almost completely rescues the Prdm16 deletion phenotype. While deletion of Prdm16 typically leads to death within 10 days, antibiotic treated mice survive at least 12 weeks after deletion. An early hallmark of the Prdm16‐deletion phenotype is the induction of the p53 pathway in the crypt. Apoptotic cells are present in high numbers, particularly in transit amplifying progenitors. Gene expression profiling of isolated small intestinal crypts indicates that the early p53 signature that is typical of Prdm16 deletion does not develop in antibiotic treated mice. Furthermore, pretreatment of mice with antibiotics prevents the severe defects normally observed when Prdm16 is deleted ex vivo in organoid cultures. However, treatment of organoids with the same antibiotics only in culture does not lead to a phenotypic rescue. We are currently characterizing how deletion of Prdm16 alters the intestinal microbiota and the effects that those changes could have on metabolite levels in the tissue. Overall, these studies aim to understand how changes in metabolic signaling can affect stem and progenitor cell behaviors and how the microbiome and, potentially, antibiotics themselves can affect the function of the intestine.

Apelin-driven endothelial cell migration sustains intestinal progenitor cells and tumor growth.

Stem and progenitor cells residing in the intestinal crypts drive the majority of colorectal cancers (CRCs), yet vascular contribution to this niche remains largely unexplored. VEGFA is a key driver of physiological and tumor angiogenesis. Accordingly, current anti-angiogenic cancer therapies target the VEGFA pathway. Here we report that in CRC expansion of the stem/progenitor pool in intestinal crypts requires VEGFA-independent growth and remodeling of blood vessels. Epithelial transformation induced expression of the endothelial peptide apelin, directs migration of distant venous endothelial cells towards progenitor niche vessels ensuring optimal perfusion. In the absence of apelin, loss of injury-inducible PROX1+ epithelial progenitors inhibited both incipient and advanced intestinal tumor growth. Our results establish fundamental principles for the reciprocal communication between vasculature and the intestinal progenitor niche and provide a mechanism for resistance to VEGFA-targeting drugs in CRCs.

Immune regulation of intestinal-stem-cell function in Drosophila.

SummaryIntestinal progenitor cells integrate signals from their niche, and the gut lumen, to divide and differentiate at a rate that maintains an epithelial barrier to microbial invasion of the host interior. Despite the importance of evolutionarily conserved innate immune defenses to maintain stable host-microbe relationships, we know little about contributions of stem-cell immunity to gut homeostasis. We used Drosophila to determine the consequences of intestinal-stem-cell immune activity for epithelial homeostasis. We showed that loss of stem-cell immunity greatly impacted growth and renewal in the adult gut. In particular, we found that inhibition of stem-cell immunity impeded progenitor-cell growth and differentiation, leading to a gradual loss of stem-cell numbers with age and an impaired differentiation of mature enteroendocrine cells. Our results highlight the importance of immune signaling in stem cells for epithelial function in the adult gut.

Measurement of activity of developmental signal transduction pathways to quantify stem cell pluripotency and phenotypically characterize differentiated cells

Important challenges in stem cell research and regenerative medicine are reliable assessment of pluripotency state and purity of differentiated cell populations. Pluripotency and differentiation are regulated and determined by activity of developmental signal transduction pathways (STPs). To date activity of these STPs could not be directly measured on a cell sample.Here we validate a novel assay platform for measurement of activity of developmental STPs (STP) for use in stem cells and stem cell derivatives. In addition to previously developed STP assays, we report development of an additional STP assay for the MAPK-AP1 pathway. Subsequently, activity of Notch, Hedgehog, TGFβ, Wnt, PI3K, MAPK-AP1, and NFκB signaling pathways was calculated from Affymetrix transcriptome data of human pluripotent embryonic (hES) and iPS cell lines under different culture conditions, organ-derived multipotent stem cells, and differentiated cell types, to generate quantitative STP activity profiles.Results show that the STP assay technology enables reliable and quantitative measurement of multiple STP activities simultaneously on any individual cell sample. Using the technology, we found that culture conditions dominantly influence the pluripotent stem cell STP activity profile, while the origin of the stem cell line was a minor variable. A pluripotency STP activity profile (Pluripotency qPAP) was defined (active PI3K, MAPK, Hedgehog, Notch, TGFβ, and NFκB pathway, inactive Wnt pathway). Differentiation of hES cells to intestinal progenitor cells resulted in an STP activity profile characterized by active PI3K, Wnt and Notch pathways, comparable to the STP activity profile measured on primary intestinal crypt stem cells. Quantitative STP activity measurement is expected to improve experimental reproducibility and standardization of pluripotent and multipotent stem cell culture/differentiation, and enable controlled manipulation of pluripotency/differentiation state using pathway targeting compounds.

Epigenetic modifier balances Mapk and Wnt signalling in differentiation of goblet and Paneth cells.

Differentiation and lineage specification are controlled by cooperation of growth factor signalling. The involvement of epigenetic regulators in lineage specification remains largely elusive. Here, we show that the histone methyltransferase Mll1 prevents intestinal progenitor cells from differentiation, whereas it is also involved in secretory lineage specification of Paneth and goblet cells. Using conditional mutagenesis in mice and intestinal organoids, we demonstrate that loss of Mll1 renders intestinal progenitor cells permissive for Wnt-driven secretory differentiation. However, Mll1-deficient crypt cells fail to segregate Paneth and goblet cell fates. Mll1 deficiency causes Paneth cell-determined crypt progenitors to exhibit goblet cell features by unleashing Mapk signalling, resulting in increased numbers of mixed Paneth/goblet cells. We show that loss of Mll1 abolishes the pro-proliferative effect of Mapk signalling in intestinal progenitor cells and promotes Mapk-induced goblet cell differentiation. Our data uncover Mll1 and its downstream targets Gata4/6 as a regulatory hub of Wnt and Mapk signalling in the control of lineage specification of intestinal secretory Paneth and goblet cells.

Coordinated repression of pro-differentiation genes via P-bodies and transcription maintains Drosophila intestinal stem cell identity

The role of processing bodies (P-bodies), key sites of post-transcriptional control, in adult stem cells remains poorly understood. Here, we report that adult Drosophila intestinal stem cells, but not surrounding differentiated cells such as absorptive enterocytes (ECs), harbor P-bodies that contain Drosophila orthologs of mammalian P-body components DDX6, EDC3, EDC4, and LSM14A/B. A targeted RNAi screen in intestinal progenitor cells identified 39 previously known and 64 novel P-body regulators, including Patr-1, a gene necessary for P-body assembly. Loss of Patr-1-dependent P-bodies leads to a loss of stem cells that is associated with inappropriate expression of EC-fate gene nubbin. Transcriptomic analysis of progenitor cells identifies a cadre of such weakly transcribed pro-differentiation transcripts that are elevated after P-body loss. Altogether, this study identifies a P-body-dependent repression activity that coordinates with known transcriptional repression programs to maintain a population of invivo stem cells in a state primed for differentiation.

RNA binding protein DDX5 directs tuft cell specification and function to regulate microbial repertoire and disease susceptibility in the intestine

ObjectiveTuft cells residing in the intestinal epithelium have diverse functions. In the small intestine, they provide protection against inflammation, combat against helminth and protist infections, and serve as entry portals...

RAL GTPases mediate EGFR-driven intestinal stem cell proliferation and tumourigenesis.

RAS-like (RAL) GTPases function in Wnt signalling-dependent intestinal stem cell proliferation and regeneration. Whether RAL proteins work as canonical RAS effectors in the intestine and the mechanisms of how they contribute to tumourigenesis remain unclear. Here, we show that RAL GTPases are necessary and sufficient to activate EGFR/MAPK signalling in the intestine, via induction of EGFR internalisation. Knocking down Drosophila RalA from intestinal stem and progenitor cells leads to increased levels of plasma membrane-associated EGFR and decreased MAPK pathway activation. Importantly, in addition to influencing stem cell proliferation during damage-induced intestinal regeneration, this role of RAL GTPases impacts on EGFR-dependent tumourigenic growth in the intestine and in human mammary epithelium. However, the effect of oncogenic RAS in the intestine is independent from RAL function. Altogether, our results reveal previously unrecognised cellular and molecular contexts where RAL GTPases become essential mediators of adult tissue homeostasis and malignant transformation.

Functional MYO5B Loss Disrupts Stem Cell Function and Differentiation of Secretory Cell Lineage

Background and Aims Differentiation of intestinal epithelial cells involves cell division inhibition, cell lineage choice, and brush border elaboration. Functional myosin Vb (MYO5B) loss causes microvillus inclusion disease (MVID) and induces a variety of deficits in enterocyte function. However, the impact of MYO5B loss on differentiated cell lineage choice had not been investigated. Since intestinal progenitor cells predominantly express MYO5B, we hypothesize that MYO5B deficiency alters stem/progenitor cell function and affects proper cell differentiation. Methods Tamoxifen-induced epithelial-specific MYO5B knockout (VilCreERT2; Myo5bflox/flox) mice were used for immunohistochemical analysis of intestinal tissues, organoid generation from crypts, and RNA-sequencing of isolated epithelial cells. We quantified the population of secretory cell lineages in utilizing whole slide imaging and digital image analysis tools. Neonatal pig intestinal organoids, possessing the Navajo mutation MYO5B(P663L), were analyzed as another MVID model that more closely represents human MVID pathology. Results Consistent with our RNA-sequencing data in epithelial cells that demonstrated decreases in Pou2f3, Spib, Dclk1, Chat, and Pgst1, MYO5B loss induced an 80% reduction in DCLK1-positive tuft cells. The frequency of TFF3-producing goblet cells was also significantly decreased. However, the Paneth cell lineage was increased by MYO5B deficiency along with expansion of the progenitor cell zone that express a Notch-dependent stem cell marker, olfactomedin (OLFM)4, and monocarboxylate transporter (MCT)1. No difference was detected in chromogranin-A-expressing enteroendocrine cells. mRNA expression indicated an increase in Notch receptor and decreases in Wnt family ligands in MYO5B deficient intestine, which may explain the alteration of cell lineages by MYO5B loss. We further investigated the effect of lysophosphatidic acid (LPA) receptor activation on epithelial sensory cell differentiation. Intraperitoneal, but not gavaged, LPA significantly increased tuft cell populations both in control and MYO5B knockout mice without alteration of mRNA expression of tuft cell-specific transcription factors. LPA did not affect hyperproliferative crypts in MYO5B deficient mice. In mouse intestinal organoids, the frequency of tuft cells was significantly decreased by 4-hydroxy-tamoxifen-induced MYO5B loss to values corresponding to undifferentiated enteroids. Intestinal organoids that were generated from MYO5B(P663L) pig jejunum had grater organoid forming rate and more proliferative cell population compared to age-matched wild type pig organoids. Differentiation of secretory cell lineages were inhibited in MYO5B(P663L) organoids similarly to the mouse model. Conclusions Functional MYO5B loss disrupts stem cell characteristics and proper differentiation in the small intestine likely through imbalance of Notch/Wnt signaling. Systemic LPA administration specifically activates tuft cell differentiation independent from MYO5B-mediated signaling pathway.

Generation of Human-Induced Pluripotent Stem Cell-Derived Functional Enterocyte-Like Cells for Pharmacokinetic Studies.

SummaryWe aimed to establish an in vitro differentiation procedure to generate matured small intestinal cells mimicking human small intestine from human-induced pluripotent stem cells (iPSCs). We previously reported the efficient generation of CDX2-expressing intestinal progenitor cells from embryonic stem cells (ESCs) using 6-bromoindirubin-3′-oxime (BIO) and (3,5-difluorophenylacetyl)-L-alanyl-L-2-phenylglycine tert-butyl ester (DAPT) to treat definitive endodermal cells. Here, we demonstrate the generation of enterocyte-like cells by culturing human iPSC-derived intestinal progenitor cells on a collagen vitrigel membrane (CVM) and treating cells with a simple maturation medium containing BIO, DMSO, dexamethasone, and activated vitamin D3. Functional tests further confirmed that these iPSC-derived enterocyte-like cells exhibit P-gp- and BCRP-mediated efflux and cytochrome P450 3A4 (CYP3A4)-mediated metabolism. We concluded that hiPS cell-derived enterocyte-like cells can be used as a model for the evaluation of drug transport and metabolism studies in the human small intestine.