Mechanisms driving fasting-induced protection from genotoxic injury in the small intestine.

Genotoxic agents such as doxorubicin (DXR) can cause damage to the intestines that can be ameliorated by fasting. How fasting is protective and the optimal timing of fasting and refeeding remain unclear. Here, our analysis of fasting/refeeding-induced global intestinal transcriptional changes revealed metabolic shifts and implicated the cellular energetic hub mechanistic target of rapamycin complex 1 (mTORC1) in protecting from DXR-induced DNA damage.

Loss of ZNRF3/RNF43 Unleashes EGFR in Cancer.

ZNRF3 and RNF43 are closely related transmembrane E3 ubiquitin ligases with significant roles in development and cancer. Conventionally, their biological functions have been associated with regulating WNT signaling receptor ubiquitination and degradation. However, our proteogenomic studies have revealed EGFR as the most negatively correlated protein with mRNA levels in multiple human cancers.

Investigation of murine host sex as a biological variable in epithelial barrier function and muscle contractility in human intestinal organoids.

Intestinal failure (IF) occurs when intestinal surface area or function is not sufficient to support digestion and nutrient absorption. Human intestinal organoid (HIO)-derived tissue-engineered intestine is a potential cure for IF. Research to date has demonstrated successful HIO transplantation (tHIO) into mice with significant in vivo maturation.

Metabolic targeting of NRF2 potentiates the efficacy of the TRAP1 inhibitor G-TPP through reduction of ROS detoxification in colorectal cancer.

Tumor necrosis factor receptor-associated protein 1 (TRAP1) is a mitochondrial homolog of HSP90 chaperones. It plays an important role in protection against oxidative stress and apoptosis by regulating reactive oxidative species (ROS). To further elucidate the mechanistic role of TRAP1 in regulating tumor cell survival, we used gamitrinib-triphenylphosphonium (G-TPP) to inhibit TRAP1 signaling pathways in colon cancer.

Genomic analysis of 1,25-dihydroxyvitamin D action in mouse intestine reveals compartment and segment-specific gene regulatory effects.

1,25-dihydroxyvitamin D (VD) regulates intestinal calcium absorption in the small intestine (SI) and also reduces risk of colonic inflammation and cancer. However, the intestine compartment-specific target genes of VD signaling are unknown. Here, we examined VD action across three functional compartments of the intestine using RNA-seq to measure VD-induced changes in gene expression and Chromatin Immunoprecipitation with next generation sequencing to measure vitamin D receptor (VDR) genomic binding.

Evaluation of Murine Host Sex as a Biological Variable in Transplanted Human Intestinal Organoid Development.

Background: Human intestinal organoids (HIOs), when transplanted into immunocompromised mice (tHIOs), demonstrate significant growth and maturation. While both male and female mice are reported to be viable hosts for these experiments, a direct comparison of sex-related differences in tHIO structure and development has not been performed.

Aims: We sought to identify host sex-related differences in tHIO engraftment, morphology, and epithelial and mesenchymal development.

Intestinal Deletion of 3-Hydroxy-3-Methylglutaryl-Coenzyme A Reductase Promotes Expansion of the Resident Stem Cell Compartment.

Background: The intestine occupies the critical interface between cholesterol absorption and excretion. Surprisingly little is known about the role of de novo cholesterol synthesis in this organ, and its relationship to whole body cholesterol homeostasis. Here, we investigate the physiological importance of this pathway through genetic deletion of the rate-limiting enzyme.

Ontogeny and function of the circadian clock in intestinal organoids.

Circadian rhythms regulate diverse aspects of gastrointestinal physiology ranging from the composition of microbiota to motility. However, development of the intestinal circadian clock and detailed mechanisms regulating circadian physiology of the intestine remain largely unknown. In this report, we show that both pluripotent stem cell-derived human intestinal organoids engrafted into mice and patient-derived human intestinal enteroids possess circadian rhythms and demonstrate circadian phase-dependent necrotic cell death responses to Clostridium difficile toxin B (TcdB).

Drivers of transcriptional variance in human intestinal epithelial organoids.

Human intestinal epithelial organoids (enteroids and colonoids) are tissue cultures used for understanding the physiology of the human intestinal epithelium. Here, we explored the effect on the transcriptome of common variations in culture methods, including extracellular matrix substrate, format, tissue segment, differentiation status, and patient heterogeneity. RNA-sequencing datasets from 276 experiments performed on 37 human enteroid and colonoid lines from 29 patients were aggregated from several groups in the Texas Medical Center.

Effect of substrate stiffness on human intestinal enteroids' infectivity by enteroaggregative Escherichia coli.

Human intestinal enteroids (HIE) models have contributed significantly to our understanding of diarrheal diseases and other intestinal infections, but their routine culture conditions fail to mimic the mechanical environment of the native intestinal wall. Because the mechanical characteristics of the intestine significantly alter how pathogens interact with the intestinal epithelium, we used different concentrations of polyethylene glycol (PEG) to generate soft (~2 kPa), medium (~10 kPa), and stiff (~100 kPa) hydrogel biomaterial scaffolds. The height of HIEs cultured in monolayers atop these hydrogels was 18 µm whereas HIEs grown on rigid tissue culture surfaces (with stiffness in the GPa range) were 10 µm.

In Vivo Transplantation of Human Intestinal Organoids Enhances Select Tight Junction Gene Expression.

Background: Short bowel syndrome is a potentially fatal condition with inadequate management options. Tissue-engineered small intestine (TESI) is a promising solution, but confirmation of TESI function will be crucial before human application. We sought to define intestinal epithelial barrier function in human intestinal organoid (HIO)-derived TESI.

Vitamin D Receptor Gene Single Nucleotide Polymorphisms and Association With Vitamin D Levels and Endoscopic Disease Activity in Inflammatory Bowel Disease Patients: A Pilot Study.

Background: Inflammatory bowel diseases (IBDs) comprise a heterogenous group of chronic gastrointestinal disorders that are multifactorial in etiology. Experimental in vitro and in vivo studies suggest that intestinal vitamin D receptor (VDR) signaling plays a role in modulating the immune response in IBD as a cause and/or a consequence of chronic inflammation.

Aim: The aim of this study is to study the associations between vitamin D receptor gene single nucleotide polymorphisms(SNPs), vitamin D levels, and endoscopic disease activity in IBD.

Analysis of 1,25-Dihydroxyvitamin D Genomic Action Reveals Calcium-Regulating and Calcium-Independent Effects in Mouse Intestine and Human Enteroids.

Although vitamin D is critical for the function of the intestine, most studies have focused on the duodenum. We show that transgenic expression of the vitamin D receptor (VDR) only in the distal intestine of VDR null mice (KO/TG mice) results in the normalization of serum calcium and rescue of rickets. Although it had been suggested that calcium transport in the distal intestine involves a paracellular process, we found that the 1,25-dihydroxyvitamin D [1,25(OH)D]-activated genes in the proximal intestine associated with active calcium transport (, , and ) are also induced by 1,25(OH)D in the distal intestine of KO/TG mice.

Enteroaggregative E. coli Adherence to Human Heparan Sulfate Proteoglycans Drives Segment and Host Specific Responses to Infection.

Enteroaggregative Escherichia coli (EAEC) is a significant cause of acute and chronic diarrhea, foodborne outbreaks, infections of the immunocompromised, and growth stunting in children in developing nations. There is no vaccine and resistance to antibiotics is rising. Unlike related E.

Telomere dysfunction activates YAP1 to drive tissue inflammation.

Germline telomere maintenance defects are associated with an increased incidence of inflammatory diseases in humans, yet whether and how telomere dysfunction causes inflammation are not known. Here, we show that telomere dysfunction drives pATM/c-ABL-mediated activation of the YAP1 transcription factor, up-regulating the major pro-inflammatory factor, pro-IL-18. The colonic microbiome stimulates cytosolic receptors activating caspase-1 which cleaves pro-IL-18 into mature IL-18, leading to recruitment of interferon (IFN)-γ-secreting T cells and intestinal inflammation.

Paneth cells promote angiogenesis and regulate portal hypertension in response to microbial signals.

Background & Aims: Paneth cells (PCs) synthesize and secrete antimicrobial peptides that are key mediators of host-microbe interactions, establishing a balance between intestinal microflora and enteric pathogens. We observed that their number increases in experimental portal hypertension and aimed to investigate the mechanisms by which these cells can contribute to the regulation of portal pressure.

Methods: We first treated Math1VilcreERT2 mice with tamoxifen to induce the complete depletion of intestinal PCs.

Models of the Small Intestine: Engineering Challenges and Engineering Solutions.

Pathologies affecting the small intestine contribute significantly to the disease burden of both the developing and the developed world, which has motivated investigation into the disease mechanisms through models. Although existing models recapitulate selected features of the intestine, various important aspects have often been isolated or omitted due to the anatomical and physiological complexity. The small intestine's intricate microanatomy, heterogeneous cell populations, steep oxygen gradients, microbiota, and intestinal wall contractions are often not included in experimental models of the small intestine, despite their importance in both intestinal biology and pathology.

Vitamin D and the intestine: Review and update.

The central role of vitamin D in calcium homeostasis is to increase calcium absorption from the intestine. This article describes the early work that served as the foundation for the initial model of vitamin D mediated calcium absorption. In addition, other research related to the role of vitamin D in the intestine, including those which have challenged the traditional model and the crucial role of specific calcium transport proteins, are reviewed.

Use of organoids to study regenerative responses to intestinal damage.

Intestinal organoid cultures provide an in vitro model system for studying pathways and mechanisms involved in epithelial damage and repair. Derived from either embryonic or induced pluripotent stem cells or adult intestinal stem cells or tissues, these self-organizing, multicellular structures contain polarized mature cells that recapitulate both the physiology and heterogeneity of the intestinal epithelium. These cultures provide a cutting-edge technology for defining regenerative pathways that are induced following radiation or chemical damage, which directly target the cycling intestinal stem cell, or damage resulting from viral, bacterial, or parasitic infection of the epithelium.

Cellular Plasticity of Defa4-Expressing Paneth Cells in Response to Notch Activation and Intestinal Injury.

Background & Aims: Loss of leucine-rich repeat-containing G-protein-coupled receptor 5-positive crypt base columnar cells provides permissive conditions for different facultative stem cell populations to dedifferentiate and repopulate the stem cell compartment. In this study, we used a defensin α4-Cre recombinase (Defa4Cre) line to define the potential of Paneth cells to dedifferentiate and contribute to intestinal stem cell (ISC) maintenance during normal homeostasis and after intestinal injury.

Methods: Small intestine and enteroids from Defa4;Rosa26 tandem dimer Tomato (tdTomato), a red fluoresent protein, (or Rosa26 Enhanced Yellow Fluorescent Protein (EYFP)) reporter, Notch gain-of-function (Defa4;Rosa26 Notch Intracellular Domain (NICD)-ires-nuclear Green Fluorescent Protein (nGFP) and Defa4;Rosa26 Enhanced Green Fluorescent Protein (EGFP);TetO), A Disintegrin and Metalloproteinase domain-containing protein 10 (ADAM10) loss-of-function (Defa4;ADAM10), and Adenomatous polyposis coli (APC) inactivation (Defa4;APC) mice were analyzed.

Is a Tumor Suppressor Gene in Colorectal Cancer.

Colorectal cancer is the third most common cancer and the third leading cause of cancer death in the United States. Growth factor-independent 1 (GFI1) is a zinc finger transcriptional repressor responsible for controlling secretory cell differentiation in the small intestine and colon. GFI1 plays a significant role in the development of human malignancies, including leukemia, lung cancer, and prostate cancer.