Reg I-knockout mice reveal its role in regulation of cell growth that is required in generation and maintenance of the villous structure of small intestine

Multiplexed immunohistochemical evaluation of small bowel inflammatory and epithelial parameters in environmental enteric dysfunction

BACKGROUND

Environmental enteric dysfunction (EED) is characterized by reduced absorptive capacity and barrier function of the small intestine, leading to poor ponderal and linear childhood growth.

OBJECTIVES

To further define gene expression patterns that are associated with EED to uncover new pathophysiology of this disorder.

METHODS

Duodenal biopsies from cohorts of children with EED from Bangladesh, Pakistan and Zambia were analyzed by immunohistochemistry (IHC) to interrogate gene products that distinguished differentiation and various biochemical pathways in immune and epithelial cells, some identified by prior bulk RNA sequence analyses. Immunohistochemical staining was digitally quantified from scanned images and compared to cohorts of North American children with celiac disease (gluten-sensitive enteropathy) or with no known enteric disease and no pathologic abnormality (NPA) detected in their clinical biopsies.

RESULTS

After multivariable statistical analysis, we identified statistically significant (P < 0.05, 2-tailed t-test) elevated signals representing cluster of differentiation 45 (80%; 95% confidence interval [CI]: 24%, 127%), lipocalin 2 (659%; 95% CI: 198%, 1838%), and regenerating family 1 beta (221%; 95% CI: 47%, 600%) and lower signals corresponding to granzyme B (-74%; 95% CI: -82%, -62%), and sucrase isomaltase (-58%; 95% CI: -75%, -29%) in EED biopsies compared with NPA biopsies. Computerized algorithms also detected statistically significant elevation in intraepithelial lymphocytes (49%; 95% CI: 9%, 105%) and proliferation of leukocytes (267%; 95% CI: 92%, 601%) in EED biopsies compared with NPA biopsies.

CONCLUSIONS

Our results support a model of chronic epithelial stress that decreases epithelial differentiation and absorptive function. The close association of several IHC parameters with manual histologic scoring suggests that automated digital quantification of IHC panels complements traditional histomorphologic assessment in EED.

Effects of L-Leu-L-Leu peptide on growth, proliferation, and apoptosis in broiler intestinal epithelial cells

Small peptides are nutrients and bioactive molecules that have dual regulatory effects on nutrition and physiology. They are of great significance for maintaining the intestinal health and production performance of broilers. We here cultured the primary small intestinal epithelial cells (IEC) of chicken in a medium containing L-Leu (Leu) and L-Leu-L-Leu (Leu-Leu) for 24 h. The untreated cells were considered as the control group. The growth, proliferation, and apoptosis of IEC were examined. By combining RNA-seq and label-free sequencing technology, candidate genes, proteins, and pathways related to the growth, proliferation, and apoptosis of IEC were screened. Immunofluorescence detection revealed that the purity of the isolated primary IEC was >90%. The Leu-Leu group significantly promoted IEC growth and proliferation and significantly inhibited IEC apoptosis, and the effect was better than those of the Leu and control groups. Using transcriptome sequencing, four candidate genes, CCL20, IL8L1, IL8, and IL6, were screened in the Leu group, and one candidate gene, IL8, was screened in the Leu-Leu group. Two candidate genes, IL6 and RGN, were screened in the Leu-Leu group compared with the Leu group. Nonquantitative proteomic marker sequencing results revealed that through the screening of candidate proteins and pathways, found one growth-related candidate protein PGM3 and three proliferation-related candidate proteins RPS17, RPS11, and RPL23, and two apoptosis-related candidate proteins GPX4 and PDPK1 were found in the Leu-Leu group compared with Leu group. In short, Leu-Leu could promote IEC growth and proliferation and inhibit IEC apoptosis. On combining transcriptome and proteome sequencing technologies, multiple immune- and energy-related regulatory signal pathways were found to be related to IEC growth, proliferation, and apoptosis. Three candidate genes of IL8, IL6, and RGN were identified, and six candidate proteins of PGM3, RPS17, RPS11, RPL23, GPX4, and PDPK1 were involved in IEC growth, proliferation, and apoptosis. The results provide valuable data for preliminarily elucidating small peptide-mediated IEC regulation pathways, improving the small peptide nutrition theoretical system, and establishing small peptide nutrition regulation technology.

N6-methyladenosine modification of REG1α facilitates colorectal cancer progression via β-catenin/MYC/LDHA axis mediated glycolytic reprogramming

Aerobic glycolysis has been considered as a hallmark of colorectal cancer (CRC). However, the potential functional regulators of glycolysis in CRC remains to be elucidated. In the current study, we found that Regenerating islet-derived protein 1-alpha (REG1α) was significantly increased in both CRC tissues and serum, and positively associated with CRC patients' lymph node metastasis, advanced tumor stage, and unfavorable prognosis. Ectopic expression of REG1α contributed to various tumorigenic properties, including cell proliferation, cell cycle, migration, invasion, and glycolysis. In contrast, REG1α deficiency in CRC cells attenuated malignant properties and glucose metabolism. Mechanically, REG1α promoted CRC proliferation and metastasis via β-catenin/MYC axis-mediated glycolysis upregulation. Moreover, the malignant behaviors governed by REG1α could be effectively abolished by silencing of Wnt/β-catenin/MYC axis or glycolysis process using specific inhibitors. Besides, REG1α expression was mediated by METTL3 in an m6A-dependent manner. Overall, our work defines a novel regulatory model of the METTL3/REG1α/β-catenin/MYC axis in CRC, which indicates that REG1α could function as a novel biomarker and a potential therapeutic target for patients with CRC.

Gene knockout inference with variational graph autoencoder learning single-cell gene regulatory networks

In this paper, we introduce Gene Knockout Inference (GenKI), a virtual knockout (KO) tool for gene function prediction using single-cell RNA sequencing (scRNA-seq) data in the absence of KO samples when only wild-type (WT) samples are available. Without using any information from real KO samples, GenKI is designed to capture shifting patterns in gene regulation caused by the KO perturbation in an unsupervised manner and provide a robust and scalable framework for gene function studies. To achieve this goal, GenKI adapts a variational graph autoencoder (VGAE) model to learn latent representations of genes and interactions between genes from the input WT scRNA-seq data and a derived single-cell gene regulatory network (scGRN). The virtual KO data is then generated by computationally removing all edges of the KO gene-the gene to be knocked out for functional study-from the scGRN. The differences between WT and virtual KO data are discerned by using their corresponding latent parameters derived from the trained VGAE model. Our simulations show that GenKI accurately approximates the perturbation profiles upon gene KO and outperforms the state-of-the-art under a series of evaluation conditions. Using publicly available scRNA-seq data sets, we demonstrate that GenKI recapitulates discoveries of real-animal KO experiments and accurately predicts cell type-specific functions of KO genes. Thus, GenKI provides an in-silico alternative to KO experiments that may partially replace the need for genetically modified animals or other genetically perturbed systems.

Interaction between gut microbiota and sex hormones and their relation to sexual dimorphism in metabolic diseases

Metabolic diseases, such as obesity, metabolic syndrome (MetS) and type 2 diabetes (T2D), are now a widespread pandemic in the developed world. These pathologies show sex differences in their development and prevalence, and sex steroids, mainly estrogen and testosterone, are thought to play a prominent role in this sexual dimorphism. The influence of sex hormones on these pathologies is not only reflected in differences between men and women, but also between women themselves, depending on the hormonal changes associated with the menopause. The observed sex differences in gut microbiota composition have led to multiple studies highlighting the interaction between steroid hormones and the gut microbiota and its influence on metabolic diseases, ultimately pointing to a new therapy for these diseases based on the manipulation of the gut microbiota. This review aims to shed light on the role of sexual hormones in sex differences in the development and prevalence of metabolic diseases, focusing on obesity, MetS and T2D. We focus also the interaction between sex hormones and the gut microbiota, and in particular the role of microbiota in aspects such as gut barrier integrity, inflammatory status, and the gut-brain axis, given the relevance of these factors in the development of metabolic diseases.

Upregulation of Reg IV and Hgf mRNAs by Intermittent Hypoxia via Downregulation of microRNA-499 in Cardiomyocytes

Sleep apnea syndrome (SAS) is characterized by recurrent episodes of oxygen desaturation and reoxygenation (intermittent hypoxia [IH]), and is a risk factor for cardiovascular disease (CVD) and insulin resistance/Type 2 diabetes. However, the mechanisms linking IH stress and CVD remain elusive. We exposed rat H9c2 and mouse P19.CL6 cardiomyocytes to experimental IH or normoxia for 24 h to analyze the mRNA expression of several cardiomyokines. We found that the mRNA levels of regenerating gene IV (Reg IV) and hepatocyte growth factor (Hgf) in H9c2 and P19.CL6 cardiomyocytes were significantly increased by IH, whereas the promoter activities of the genes were not increased. A target mRNA search of microRNA (miR)s revealed that rat and mouse mRNAs have a potential target sequence for miR-499. The miR-499 level of IH-treated cells was significantly decreased compared to normoxia-treated cells. MiR-499 mimic and non-specific control RNA (miR-499 mimic NC) were introduced into P19.CL6 cells, and the IH-induced upregulation of the genes was abolished by introduction of the miR-499 mimic, but not by the miR-499 mimic NC. These results indicate that IH stress downregulates the miR-499 in cardiomyocytes, resulting in increased levels of Reg IV and Hgf mRNAs, leading to the protection of cardiomyocytes in SAS patients.

A genome-scale CRISPR screen reveals factors regulating Wnt-dependent renewal of mouse gastric epithelial cells

An ability to safely harness the powerful regenerative potential of adult stem cells for clinical applications is critically dependent on a comprehensive understanding of the underlying mechanisms regulating their activity. Epithelial organoid cultures accurately recapitulate many features of in vivo stem cell-driven epithelial renewal, providing an excellent ex vivo platform for interrogation of key regulatory mechanisms. Here, we employed a genome-scale clustered, regularly interspaced, short palindromic repeats (CRISPR) knockout (KO) screening assay using mouse gastric epithelial organoids to identify modulators of Wnt-driven stem cell-dependent epithelial renewal in the gastric mucosa. In addition to known Wnt pathway regulators, such as Apc, we found that KO of Alk, Bclaf3, or Prkra supports the Wnt independent self-renewal of gastric epithelial cells ex vivo. In adult mice, expression of these factors is predominantly restricted to non-Lgr5-expressing stem cell zones above the gland base, implicating a critical role for these factors in suppressing self-renewal or promoting differentiation of gastric epithelia. Notably, we found that Alk inhibits Wnt signaling by phosphorylating the tyrosine of Gsk3β, while Bclaf3 and Prkra suppress regenerating islet-derived (Reg) genes by regulating the expression of epithelial interleukins. Therefore, Alk, Bclaf3, and Prkra may suppress stemness/proliferation and function as novel regulators of gastric epithelial differentiation.

Okamoto model for necrosis and its expansions, CD38-cyclic ADP-ribose signal system for intracellular Ca2+ mobilization and Reg (Regenerating gene protein)-Reg receptor system for cell regeneration

In pancreatic islet cell culture models and animal models, we studied the molecular mechanisms involved in the development of insulin-dependent diabetes. The diabetogenic agents, alloxan and streptozotocin, caused DNA strand breaks, which in turn activated poly(ADP-ribose) polymerase/synthetase (PARP) to deplete NAD+, thereby inhibiting islet β-cell functions such as proinsulin synthesis and ultimately leading to β-cell necrosis. Radical scavengers protected against the formation of DNA strand breaks and inhibition of proinsulin synthesis. Inhibitors of PARP prevented the NAD+ depletion, inhibition of proinsulin synthesis and β-cell death. These findings led to the proposed unifying concept for β-cell damage and its prevention (the Okamoto model). The model met one proof with PARP knockout animals and was further extended by the discovery of cyclic ADP-ribose as the second messenger for Ca2+ mobilization in glucose-induced insulin secretion and by the identification of Reg (Regenerating gene) for β-cell regeneration. Physiological and pathological events found in pancreatic β-cells have been observed in other cells and tissues.

Molecular Changes in the Non-Inflamed Terminal Ileum of Patients with Ulcerative Colitis

Ulcerative colitis is a chronic inflammatory disease confined to the colon. Although the etiopathogenesis remains unknown, small bowel dysfunctions like histological and permeability alterations have been described in ulcerative colitis. We evaluated the molecular gene signature in the non-inflamed terminal ileum of 36 ulcerative colitis patients (7 active, with Mayo endoscopic subscore ≥2, and 29 inactive) as compared to 15 non-inflammatory bowel disease controls. Differential gene expression analysis with DESeq2 showed distinct expression patterns depending on disease activity and maximal disease extent. We found 84 dysregulated genes in patients with active extensive colitis and 20 in inactive extensive colitis, compared to controls. There was an overlap of 5 genes: REG1B, REG1A, MUC4, GRAMD2, and CASP10. In patients with left-sided colitis, ileal gene expression levels were similar to controls. Based on gene co-expression analysis, ileal changes in active ulcerative colitis patients were related to immune functions. The ileal changes in the inactive ulcerative colitis subjects converged into the maintenance of the intestinal barrier through increased mitochondrial function and dampened immune functions. In conclusion, we identified molecular changes in the non-inflamed ileum of ulcerative colitis that are dependent on colonic inflammation.

Role of regenerating islet-derived proteins in inflammatory bowel disease

Inflammatory bowel disease (IBD) is an inflammatory disorder of the gastrointestinal tract that affects millions of patients worldwide. It has a complex and multifactorial etiology leading to excessive exposure of intestinal epithelium to microbial antigens, inappropriate activation of the immune system and ultimately to the damage of intestinal tissues. Although numerous efforts have been made to improve the disease management, IBD remains persistently recurring and beyond cure. This is due largely to the gaps in our understanding of the pathogenesis of IBD that hamper the development of timely diagnoses and effective treatment. However, some recent discoveries, including the beneficial effects of interleukin-22 (IL-22) on the inflamed intestine, have shed light on a self-protective mechanism in IBD. Regenerating islet-derived (REG/Reg) proteins are small secretory proteins which function as IL-22's downstream effectors. Mounting studies have demonstrated that IBD patients have significantly increased REG expressions in the injured intestine, but with undefined mechanisms and roles. The reported functions of REG/Reg proteins in intestinal homeostasis, such as those of antibacterial, anti-inflammatory and tissue repair, lead us to discuss their potential mechanisms and clinical relevance in IBD in order to advance IBD research and management.

Four Decades After the Discovery of Regenerating Islet-Derived (Reg) Proteins: Current Understanding and Challenges

Regenerating islet-derived (Reg) proteins have emerged as multifunctional agents with pro-proliferative, anti-apoptotic, differentiation-inducing and bactericidal properties. Over the last 40 years since first discovered, Reg proteins have been implicated in a gamut of maladies including diabetes, various types of cancer of the digestive tract, and Alzheimer disease. Surprisingly though, a consensus is still absent on the regulation of their expression, and molecular underpinning of their function. Here, we provide a critical appraisal of recent findings in the field of Reg protein biology. Specifically, the structural characteristics are reviewed particularly in connection with established or purported functions of different members of the Reg family. Moreover, Reg expression patterns in different tissues both under normal and pathophysiological conditions are summarized. Putative receptors and cascades reported to relay Reg signaling inciting cellular responses are presented aiming at a better appreciation of the biological activities of the distinct Reg moieties. Challenges are also discussed that have hampered thus far the rapid progress in this field such as the use of non-standard nomenclature for Reg molecules among various research groups, the existence of multiple Reg members with significant degree of homology and possibly compensatory modes of action, and the need for common assays with robust readouts of Reg activity. Coordinated research is warranted going forward, given that several research groups have independently linked Reg proteins to diseased states and raised the possibility that these biomolecules can serve as therapeutic targets and biomarkers.

Knockdown of REG Iα Enhances the Sensitivity to 5-Fluorouracil of Colorectal Cancer Cells via Cyclin D1/CDK4 Pathway and BAX/BCL-2 Pathways

Objective: The reverse of chemoresistance and the improvement of sensitivity to chemotherapeutic agents of colorectal cancer cells have great clinical significance and the mechanism underlying the drug resistance is still unclear. REG Iα was reported to be upregulated in colorectal cancer tissues, but the roles of chemoresistance are still unclear. Materials and Methods: The expression of REG Iα in colorectal cancer cell lines was assessed by quantitative real-time polymerase chain reaction (Q-PCR). The expression of REG Iα in HCT116 and LOVO cells was knockdown by siRNA. The cell viability and IC₅₀ (half maximal inhibitory concentration) values were analyzed by the CCK8 assay. The proportion of apoptosis and cell cycles were analyzed by flow cytometry. The migration potency of HCT116 and LOVO cells was analyzed by cell migration assay. The protein level of Cyclin D1, CDK4 (cyclin-dependent kinase 4), Bax and Bcl-2 were analyzed by western blot. Results: Knockdown of REG Iα enhances the sensitivity to 5-Fu of colorectal cancer cells. REG Iα knockdown promoted the cell apoptosis of HCT116 and LOVO under the 5-Fu treatment. The cell migration and cycle of colorectal cancer cells was also inhibited by REG Iα knockdown. We also found that REG Iα knockdown induced cell cycle arrest and cell apoptosis by Cyclin D1/CDK4 pathway and BAX/BCL-2 pathways. Conclusions: Knockdown of REG Iα enhances the sensitivity to 5-Fu of colorectal cancer cells via cyclin D1/CDK4 pathway and BAX/BCL-2 pathways.

The role of diet and intestinal microbiota in the development of metabolic syndrome

Metabolic syndrome (MetS) is a cluster of metabolic factors that increase the risk of cardiovascular disease and type 2 diabetes mellitus (T2DM), which is in itself a major cardiovascular disease risk factor. The aim of this review is to summarize the data related to the influence of the gut microbiota on the development of obesity and the MetS, highlighting the role of diet in controlling the MetS by modifying the gut microbiota. The main alterations in the gut microbiota of individuals with MetS consist of an increased Firmicutes/Bacteriodetes ratio and a reduced capacity to degrade carbohydrates to short-chain fatty acids, which in turn is related with the metabolic dysfunction of the host organism rather than with obesity itself. In addition to a low-fat, high-carbohydrate diet, with its high fiber intake, a diet with 30% fat content but with a high content in fruit and vegetables, such as the Mediterranean diet, is beneficial and partially restores the dysbiosis found in individuals with MetS. Overall, the shaping of the gut microbiota through the administration of prebiotics or probiotics increases the short-chain fatty acid production and is therefore a valid alternative in MetS treatment.

Proteomic analysis of AQP11-null kidney: Proximal tubular type polycystic kidney disease

Autosomal Dominant Polycystic Kidney Disease (ADPKD) is caused by the mutation of polycystins (PC-1 or PC-2), in which cysts start from the collecting duct to extend to all nephron segments with eventual end stage renal failure. The cyst development is attenuated by a vasopressin V2 receptor antagonist tolvaptan which, however, will not affect proximal tubule cysts devoid of V2 receptor. Aquaporin-11 (AQP11) is expressed selectively in the proximal tubule of the kidney and AQP11-null kidneys have a disruptive PC-1 trafficking to the plasma membrane to develop polycystic kidneys. Here, we analyzed AQP11-null kidneys at the beginning of cyst formation by quantitative proteomic analysis using Tandem Mass Tag (TMT). Among ~ 1200 identified proteins, 124 proteins were differently expressed by > 1.5 or < 0.8 fold change. A pancreatic stone inhibitor or a growth factor, lithostathine-1 (Reg1) was most enhanced by 5 folds which was confirmed by western blot, while mitochondria-related proteins were downregulated. The identified proteins will be new target molecules for the treatment of proximal tubular cysts and helpful to explore the functional roles of AQP11 in the kidney.

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Proteomic analysis of the kidney from AQP11-null mice of proximal tubular specific ADPKD.

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Among ~ 1200 identified proteins, 124 proteins were differently expressed by > 1.5 or < 0.8 fold change.

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Mitochondrial proteins were downregulated reflecting a functional mitochondrial damage in cystic epithelia.

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Reg1 protein was most enhanced by 5 folds which was confirmed by western blot.

Expression of REG family genes in human inflammatory bowel diseases and its regulation

The pathophysiology of inflammatory bowel disease (IBD) reflects a balance between mucosal injury and reparative mechanisms. Some regenerating gene (Reg) family members have been reported to be expressed in Crohn's disease (CD) and ulcerative colitis (UC) and to be involved as proliferative mucosal factors in IBD. However, expression of all REG family genes in IBD is still unclear. Here, we analyzed expression of all REG family genes (REG Iα, REG Iβ, REG III, HIP/PAP, and REG IV) in biopsy specimens of UC and CD by real-time RT-PCR. REG Iα, REG Iβ, and REG IV genes were overexpressed in CD samples. REG IV gene was also overexpressed in UC samples. We further analyzed the expression mechanisms of REG Iα, REG Iβ, and REG IV genes in human colon cells. The expression of REG Iα was significantly induced by IL-6 or IL-22, and REG Iβ was induced by IL-22. Deletion analyses revealed that three regions (- 220 to - 211, - 179 to - 156, and - 146 to - 130) in REG Iα and the region (- 274 to- 260) in REG Iβ promoter were responsible for the activation by IL-22/IL-6. The promoters contain consensus transcription factor binding sequences for MZF1, RTEF1/TEAD4, and STAT3 in REG Iα, and HLTF/FOXN2F in REG Iβ, respectively. The introduction of siRNAs for MZF1, RTEF1/TEAD4, STAT3, and HLTF/FOXN2F abolished the transcription of REG Iα and REG Iβ. The gene activation mechanisms of REG Iα/REG Iβ may play a role in colon mucosal regeneration in IBD.

Gata4 is critical to maintain gut barrier function and mucosal integrity following epithelial injury

The intestinal epithelial barrier is critical to limit potential harmful consequences from exposure to deleterious luminal contents on the organism. Although this barrier is functionally important along the entire gut, specific regional regulatory mechanisms involved in the maintenance of this barrier are poorly defined. Herein, we identified Gata4 as a crucial regulator of barrier integrity in the mouse proximal intestinal epithelium. Conditional deletion of Gata4 in the intestine led to a drastic increase in claudin-2 expression that was associated with an important increase of gut barrier permeability without causing overt spontaneous inflammation. Administration of indomethacin, a non-steroidal anti-inflammatory drug (NSAID) that causes enteritis, led to rapid and restricted proximal small intestinal injuries in Gata4 mutant mice as opposed to control mice. Comparative analysis of gene transcript profiles from indomethacin-challenged control and Gata4 mutant mice identified defects in epithelial cell survival, inflammatory cell recruitment and tissue repair mechanisms. Altogether, these observations identify Gata4 as a novel crucial regulator of the intestinal epithelial barrier and as a critical epithelial transcription factor implicated in the maintenance of proximal intestinal mucosal integrity after injury.

Effect of resveratrol on cancer progression through the REG Ⅲ expression pathway in head and neck cancer cells

Identification of reliable markers of chemo- and radiosensitivity and the key molecules that enhance the susceptibility of head and neck squamous cell carcinoma (HNSCC) to anticancer treatments is highly desirable. Previously, we have reported that regenerating gene (REG) Ⅲ expression was such a marker associated with an improved survival rate for HNSCC patients. In the present study, we investigated the stimulators for induction of REG Ⅲ expression using REG Ⅲ promoter assay in HNSCC cells transfected with REG Ⅲ promoter vector. We tested inflammatory cytokines, growth factors, polyphenols, PPARγ activator of thiazolidinediones, and histone deacetylase inhibitors, and found that 3,4',5-trihydroxy-trans-stilbene (resveratrol) significantly increased the REG Ⅲ promoter activity and the mRNA levels of REG Ⅲ in HNSCC cells. Moreover, we demonstrated the effect of resveratrol on cancer cell progression, such as cell proliferation, chemo‑ and radiosensitivity and cancer invasion of HNSCC cells. Resveratrol significantly inhibited cell growth, enhanced chemo‑ and radiosensitivity, and blocked cancer invasion of HNSCC cells. These data suggested that resveratrol could inhibit cancer progression through the REG Ⅲ expression pathway in HNSCC cells.

The Role of Probiotics on the Microbiota: Effect on Obesity

The microbiota and the human host maintain a symbiotic association. Nowadays, metagenomic analyses are providing valuable knowledge on the diversity and functionality of the gut microbiota. However, with regard to the definition of a "healthy microbiota" and the characterization of the dysbiosis linked to obesity, there is still not a clear answer. Despite this fact, attempts have been made to counteract obesity through probiotic supplementation. A literature search of experimental studies relevant to the topic was performed in PubMed database with the keywords "probiotic" and "obesity" and restricted to those with "Lactobacillus" or "Bifidobacterium" in the title. So far, evidence of an antiobesity effect of different lactobacilli and bifidobacteria has been mainly obtained from animal models of dietary-induced obesity. Using these experimental models, a substantial number of studies have reported reductions in weight gain and, in particular, fat tissue mass at different locations following administration of bacteria, as compared with controls. Antiatherogenic and anti-inflammatory effects-including regulation of expression of lipogenic and lipolytic genes in the liver, reduction in liver steatosis, improvement of blood lipid profile and glucose tolerance, decreased endotoxemia, and regulation of inflammatory pathways-are also reported in many of them. The number of human studies focused on probiotic administration for obesity management is still very scarce, and it is too soon to judge their potential efficacy, especially when considering the fact that the actions of probiotics are always strain specific and the individual response varies according to intrinsic factors, the overall composition of diet, and their interactions.

Identification of GATA-4 as a novel transcriptional regulatory component of regenerating islet-derived family members

Intestinal epithelial cells are exposed to luminal bacterial threat and require adequate defense mechanisms to ensure host protection and epithelium regeneration against possible deleterious damage. Differentiated intestinal epithelial cells produce antimicrobial and regenerative components that protect against such challenges. Few intestinal specific transcription factors have been identified to control the switching from repression to activation of this class of gene. Herein, we show that gene transcription of some regenerating islet-derived (REG) family members is dependent on the transcription factor GATA-4. Silencing of GATA-4 expression in cultured intestinal epithelial cells identified Reg3β as a target gene using an unbiased approach of gene expression profiling. Co-transfection and RNA interference assays identified complex GATA-4-interactive transcriptional components required for the activation or repression of Reg3β gene activity. Conditional deletion of Gata4 in the mouse intestinal epithelium supported its regulatory role for Reg1, Reg3α, Reg3β and Reg3γ genes. Reg1 dramatic down-modulation of expression in Gata4 conditional null mice was associated with a significant decrease in intestinal epithelial cell migration. Altogether, these results identify a novel and complex role for GATA-4 in the regulation of REG family members gene expression.

Relationship between Reg proteins and intestinal mucosa barrier damage in rats with severe acute pancreatitis

AIM: To detect the expression of regenerating islet-derived proteins (Reg)Ⅰand Ⅲ in the intestinal mucosa of rats with severe acute pancreatitis (SAP), and to evaluate the relationship between the levels of RegⅠand Ⅲ and intestinal mucosal barrier damage.

METHODS: Seventy-two adult SD rats were randomly divided into three groups: a normal control (N) group, an SAP (S) group, and a pyrrolidine dithiocarbamate (PDTC, 10 mg/kg) pretreatment (P) group. Each group was further divided into two subgroups for testing at different time points (12 and 24 h), with 12 rats in each subgroup. The rats in the S group were given 20% L-arginine (L-Arg, 2.5 g/kg) by intraperitoneal injection twice at one-hour interval to induce SAP. The N group was given equal volume of normal saline. The P group was given PDTC 10 mg/kg by intraperitoneal injection 1 h before the first injection of L-Arg. All rats were killed 12 h or 24 h after L-Arg injection to collect blood, pancreatic and intestinal tissue samples. The pathological changes in pancreatic and intestinal tissues were observed and graded under an optical microscope. ELISA was used to detect the levels of serum interleukin 22 (IL-22), tumor necrosis factor-α (TNF-α) and intestinal fatty acid binding protein (I-FABP). The expression of RegⅠand Ⅲ mRNAs in intestinal tissue was evaluated by RT-PCR. The levels of RegⅠ, Ⅲ and nuclear-factor κB (NF-κB) proteins in intestinal tissue were detected by Western blot.

RESULTS: In the SAP group, the scores of pancreatic changes (12 h: 8.92 ± 1.130; 24 h: 11.31 ± 1.609) and intestinal mucosal changes (12 h: 3.79 ± 0.689, 24 h: 4.33 ± 0.354), and the levels of IL-22 (12 h: 712.46 ng/mL ± 81.549 ng/mL, 24 h: 751.02 ng/mL ± 104.054 ng/mL), TNF-α (12 h: 138.08 ng/mL ± 20.369 ng/mL, 24 h: 159.43 ng/mL ± 24.46 ng/mL), I-FABP (12 h: 338.04 IU/mL ± 61.876 IU/mL, 24 h: 395.26 IU/mL ± 58.547 IU/mL), intestinal NF-κB p65 (12 h: 0.51 ± 0.065, 24 h: 0.60 ± 0.066), RegⅠprotein (12 h: 0.45 ± 0.047, 24 h: 0.56 ± 0.033), and Reg Ⅲ protein (12 h: 0.70 ± 0.084, 24 h: 0.92 ± 0.163) were significantly higher (P < 0.05) than those in the control group. Compared with the S group, pretreatment with different doses of PDTC significantly decreased the above parameters (P < 0.05), although the levels of these parameters were still significantly higher than those in the N group (P < 0.05). There were positive correlations among RegⅠand Ⅲ protein expression, intestinal mucosal pathological score, IL-22, I-FABP, TNF-α, and NF-κB p65 expression.

CONCLUSION: RegⅠand Ⅲ protein expression is upregulated in SAP, which is possibly associated with intestinal mucosa damage and NF-κB signaling pathway activation.

Hes1 promotes the IL-22-mediated antimicrobial response by enhancing STAT3-dependent transcription in human intestinal epithelial cells

Notch signaling plays an essential role in the proliferation and differentiation of intestinal epithelial cells (IECs). We have previously shown that Notch signaling is up-regulated in the inflamed mucosa of ulcerative colitis (UC) and thereby plays an indispensable role in tissue regeneration. Here we show that in addition to Notch signaling, STAT3 signaling is highly activated in the inflamed mucosa of UC. Forced expression of the Notch target gene Hes1 dramatically enhanced the IL-22-mediated STAT3-dependent transcription in human IECs. This enhancement of STAT3-dependent transcription was achieved by the extended phosphorylation of STAT3 by Hes1. Microarray analysis revealed that Hes1-mediated enhancement of IL-22-STAT3 signaling significantly increased the induction of genes encoding antimicrobial peptides, such as REG1A, REG3A and REG3G, in human IECs. Conversely, the reduction of Hes1 protein levels with a γ-secretase inhibitor significantly down-regulated the induction of those genes in IECs, resulting in a markedly poor response to IL-22. Our present findings identify a new role for the molecular function of Hes1 in which the protein can interact with cytokine signals and regulate the immune response of IECs.

HDAC1 and HDAC2 restrain the intestinal inflammatory response by regulating intestinal epithelial cell differentiation

Acetylation and deacetylation of histones and other proteins depends on histone acetyltransferases and histone deacetylases (HDACs) activities, leading to either positive or negative gene expression. HDAC inhibitors have uncovered a role for HDACs in proliferation, apoptosis and inflammation. However, little is known of the roles of specific HDACs in intestinal epithelial cells (IEC). We investigated the consequences of ablating both HDAC1 and HDAC2 in murine IECs. Floxed Hdac1 and Hdac2 homozygous mice were crossed with villin-Cre mice. Mice deficient in both IEC HDAC1 and HDAC2 weighed less and survived more than a year. Colon and small intestinal sections were stained with hematoxylin and eosin, or with Alcian blue and Periodic Acid Schiff for goblet cell identification. Tissue sections from mice injected with BrdU for 2 h, 14 h and 48 h were stained with anti-BrdU. To determine intestinal permeability, 4-kDa FITC-labeled dextran was given by gavage for 3 h. Microarray analysis was performed on total colon RNAs. Inflammatory and IEC-specific gene expression was assessed by Western blot or semi-quantitative RT-PCR and qPCR with respectively total colon protein and total colon RNAs. HDAC1 and HDAC2-deficient mice displayed: 1) increased migration and proliferation, with elevated cyclin D1 expression and phosphorylated S6 ribosomal protein, a downstream mTOR target; 2) tissue architecture defects with cell differentiation alterations, correlating with reduction of secretory Paneth and goblet cells in jejunum and goblet cells in colon, increased expression of enterocytic markers such as sucrase-isomaltase in the colon, increased expression of cleaved Notch1 and augmented intestinal permeability; 3) loss of tissue homeostasis, as evidenced by modifications of claudin 3 expression, caspase-3 cleavage and Stat3 phosphorylation; 4) chronic inflammation, as determined by inflammatory molecular expression signatures and altered inflammatory gene expression. Thus, epithelial HDAC1 and HDAC2 restrain the intestinal inflammatory response, by regulating intestinal epithelial cell proliferation and differentiation.

Biomarkers for diagnosis and monitoring of celiac disease

Celiac disease (CD) is an autoimmune disorder, which damages the small intestine and is caused by ingestion of gluten in genetically susceptible individuals. The only known effective treatment is a lifelong gluten-free diet. Genetic risk factors have been identified and nearly all patients are HLA-DQ2 and/or HLA-DQ8 positive. Specific autoantibodies, IgA antitissue transglutaminase-2, antiendomysium, and antideaminated forms of gliadin peptide antibodies, are widely used as diagnostic aids in celiac patients. However, the discovery of new biomarkers may help in the diagnosis and follow-up of the disease. Recently, the molecule REG Iα, involved in tissue regeneration, has been proposed as a new biomarker of CD. REG Iα expression is increased in the target tissue and in the sera of celiac patients during damage and inflammation, decreasing after gluten-free diet. In this article we review the main biomarkers for diagnosis and monitoring of CD, focusing on the immune response-related mechanisms.

High expression of gastrin receptor protein in injured mucosa of Helicobacter pylori-positive gastritis

BACKGROUND AND AIM

Gastrin is a growth factor for the gastric epithelial cells. However, it is unknown how gastric receptor (GR) expression is regulated in the gastric mucosa. We studied GR expression using a newly raised antibody and investigated the relationship between GR expression and gastritis.

METHODS

Gastric receptor expression in 63 human gastric mucosa was studied. Helicobacter pylori infection and histological gastritis status were evaluated in gastric biopsy samples. In gastric ulcer cases, additional biopsy specimens were taken from injured mucosa. Fasting sera were collected and serum gastrin level evaluated. MKN-28 cells were cultured at various pH conditions, and the change in GR expression was determined.

RESULTS

Gastric receptor expression was detected in the foveolar epithelium of the gastric mucosa, and its expression was stronger in patients infected with H. pylori. In particular, higher expression was detected in regenerating injured mucosa. There was no association between gastritis score/serum gastrin level and GR expression in H. pylori-positive cases. In MKN-28 cells, GR protein expression was lower in neutral conditions than in acidic or alkaline conditions.

CONCLUSION

Gastric mucosal injury with H. pylori infection destroys the pH barrier on the foveolar epithelium and may induce GR expression through pH changes.

Reelin is involved in the crypt-villus unit homeostasis

Intestinal myofibroblasts secrete substances that control organogenesis and wound repair of the intestine. The myofibroblasts of the rat small intestine express reelin and the present work explores whether reelin regulates crypt-villus unit homeostasis using normal mice and mice with the reelin gene disrupted (reeler). The results reveal that mouse small intestine expresses reelin, its receptors apolipoprotein E receptor 2 (ApoER2) and very low-density lipoprotein receptor (VldlR) and the reelin effector protein Disabled-1 (Dab1) and that reelin expression is restricted to myofibroblasts. The absence of reelin significantly reduces epithelial cell proliferation, migration, and apoptosis and the number of Paneth cells. These effects are observed during the suckling, weaning, and adult periods. The number of Goblet cells is increased in the 2-month-old reeler mice. The absence of reelin also expands the extracellular space of the adherens junctions and desmosomes without significantly affecting either the tight-junction structure or the epithelial paracellular permeability. In conclusion, this is the first in vivo work showing that the absence of reelin alters intestinal epithelium homeostasis.

New insights into the role of STAT3 in IBD

Although it is clear that inflammatory bowel disease (IBD) involves an inappropriate immune response to floral components, the molecular determinants that mediate the gene transcription underlying and aggravating disease remain poorly understood. There is building momentum, however, that implicates differential regulation of the signal transducer and activator of transcription (STAT) 3 as an important factor in mediating pathogenic gene transcription in IBD, and this notion was reinforced by studies presented at the recent 2011 Digestive Disease Week (DDW) conference in Chicago. In the present report we integrate the existing body of literature with the novel data presented at this meeting to present a kaleidoscopic scheme so as to provide further insight into the role of STAT3 in IBD. A genetic propensity to its overactivation in the monocyte and epithelial compartment compromises the innate defense to allow low-level bacterial infection to fester and eventually initiate disease. The subsequent STAT3 activation in various relevant mucosal immune compartments, in particular epithelial cell proliferation and survival, and the function of the regulatory T cells and Th17 cells allow the mucosal immune system to fight the infection and return to steady state. As such, the action of STAT3 in IBD is highly context-dependent but always important.

Regenerating proteins and their expression, regulation and signaling

The regenerating (Reg) protein family comprises C-type lectin-like proteins discovered independently during pancreatitis and pancreatic islet regeneration. However, an increasing number of studies provide evidence of participation of Reg proteins in the proliferation and differentiation of diverse cell types. Moreover, Reg family members are associated with various pathologies, including diabetes and forms of gastrointestinal cancer. These findings have led to the emergence of key roles for Reg proteins as anti-inflammatory, antiapoptotic and mitogenic agents in multiple physiologic and disease contexts. Yet, there are significant gaps in our knowledge regarding the regulation of expression of different Reg genes. In addition, the pathways relaying Reg-triggered signals, their targets and potential cross-talk with other cascades are still largely unknown. In this review, the expression patterns of different Reg members in the pancreas and extrapancreatic tissues are described. Moreover, factors known to modulate Reg levels in different cell types are discussed. Several signaling pathways, which have been implicated in conferring the effects of Reg ligands to date, are also delineated. Further efforts are necessary for elucidating the biological processes underlying the action of Reg proteins and their involvement in various maladies. Better understanding of the function of Reg genes and proteins will be beneficial in the design and development of therapies utilizing or targeting this protein group.

Regenerating gene Iα is a biomarker for diagnosis and monitoring of celiac disease: a preliminary study

The regenerating gene (REG) is a multigene family in humans that plays a role in tissue regeneration. The REG Iα protein is expressed in the pancreas and the gastrointestinal tract and is involved in the pathophysiology of gastritis, pancreatitis, cancer, inflammatory bowel disease, and type 1 diabetes (T1D). Celiac disease (CD) is an autoimmune disease caused by the ingestion of gluten in genetically susceptible individuals. Our aim was to determine whether the serum REG Iα concentration reflects the destructive/regenerative process in the small bowel in CD. REG Iα was determined by enzyme-linked immunosorbent assay (ELISA) in 40 patients with active CD, and in 19 of them, REG Iα was assessed after following a gluten free diet. As controls, 35 healthy subjects were included in the study. Autoantibodies to transglutaminase, gliadin, and endomisium were measured also. We found a significant increase in REG Iα in the sera of CD patients when compared with controls. REG Iα levels decreased after a gluten-free diet together with a significant reduction in antitransglutaminase antibodies. T1D and pernicious anemia patients displayed normal serum REG Iα concentrations. This preliminary study suggests that REG Iα protein levels can be used as a biomarker for the diagnosis and monitoring of CD.

Bifidobacterium longum supplementation improved high-fat-fed-induced metabolic syndrome and promoted intestinal Reg I gene expression

Recent evidence suggests that intestinal Bifidobacterium species (spp.) positively correlates with improved insulin resistance and obesity, and this might be linked to metabolic inflammation. The expression of intestinal REG (regenerating) family proteins which are widely involved in inflammatory bowel disease and diabetes are still unknown in metabolic syndrome. Hence, we investigated the effects of Bifidobacterium longum (BIF) supplementation on metabolic parameters, intestinal function and expression of Reg family genes in a rat model of metabolic syndrome induced by a high-fat (HF) diet. We specifically increased the gut bifidobacterial content of HF-fed rats through BIF supplementation. Compared with the normal chow-fed control rats, HF feeding significantly reduced intestinal Bifidobacterium. As expected, BIF supplementation fed rats had totally restored quantities of Bifidobacterium. HF diet-fed rats showed significant increase in body weight, fat deposits, systolic blood pressure, fasting glucose, fasting triglycerides and reduced insulin sensitivity, while increases of intestinal Bifidobacterium did improve HF-diet-induced metabolic disorders. HF feeding led to significantly higher levels of the plasma lipopolysaccharide, interleukin-1β and intestinal myeloperoxidase, as well as intestinal inflammatory activity index, while these parameters were normalized to the control levels in the HF + BIF-treated rats. The levels of RegI mRNA and protein in the HF + BIF group were significantly higher than the control and the HF groups. Increasing Bifidobacterium in the gut improved HF-fed-induced metabolic syndrome by reducing metabolic endotoxin concentrations and intestinal inflammation, as well as upgrading the expression of intestinal Reg I as a regulator of growth factor.

SWI/SNF complexes containing Brahma or Brahma-related gene 1 play distinct roles in smooth muscle development

SWI/SNF ATP-dependent chromatin-remodeling complexes containing either Brahma-related gene 1 (Brg1) or Brahma (Brm) play important roles in mammalian development. In this study we examined the roles of Brg1 and Brm in smooth muscle development, in vivo, through generation and analysis of mice harboring a smooth muscle-specific knockout of Brg1 on wild-type and Brm null backgrounds. Knockout of Brg1 from smooth muscle in Brg1(flox/flox) mice expressing Cre recombinase under the control of the smooth muscle myosin heavy-chain promoter resulted in cardiopulmonary defects, including patent ductus arteriosus, in 30 to 40% of the mice. Surviving knockout mice exhibited decreased expression of smooth muscle-specific contractile proteins in the gastrointestinal tract, impaired contractility, shortened intestines, disorganized smooth muscle cells, and an increase in apoptosis of intestinal smooth muscle cells. Although Brm knockout mice had normal intestinal structure and function, knockout of Brg1 on a Brm null background exacerbated the effects of knockout of Brg1 alone, resulting in an increase in neonatal lethality. These data show that Brg1 and Brm play critical roles in regulating development of smooth muscle and that Brg1 has specific functions within vascular and gastrointestinal smooth muscle that cannot be performed by Brm.

Expression of Reg family proteins in embryonic stem cells and its modulation by Wnt/beta-catenin signaling

Regenerating islet (Reg) proteins are involved in the proliferation and differentiation of diverse cell types. However, whether embryonic stem cells (ESCs) express Reg genes and their corresponding proteins remains unknown. In this study, we probed the expression of Reg family members by mouse ESCs (mESCs). Mouse Reg1 and Reg3gamma were detected in undifferentiated stem cells. Furthermore, we tested if gastrin--an inducer of Reg1 expression in committed cells--up-regulates the Reg1 gene in mESCs. Gastrin did not affect the expression of Reg1 either in self-renewing mESCs or under conditions permitting their differentiation. Moreover, overexpression of Reg genes found in various forms of cancer has been linked to dysregulated activation of the canonical Wnt/beta-catenin cascade. Given the important roles of Wnt signaling in stem cells, we investigated if activation of Wnt alters the expression of Reg genes in mESCs. Wnt activation led to an increase in Reg1 gene expression with a concomitant increase in the amount of secreted Reg1 protein. Finally, the expression pattern of genes indicative of differentiation was examined in mESCs that were either exposed to soluble Reg1 or overexpressed the Reg1 gene. This is the first account of expression of Reg family members by ESCs. Our results show that the canonical Wnt cascade affects Reg expression and warrants further studies into the potential roles of Reg proteins in stem cell physiology.

Exacerbation of indomethacin-induced small intestinal injuries in Reg I-knockout mice

Nonsteroidal anti-inflammatory drug (NSAID)-induced small intestinal injuries are serious clinical events and a successful therapeutic strategy is difficult. Regenerating gene (Reg) I protein functions as a regulator of cell proliferation and maintains intercellular integrity in the small intestine. The aim of this study was to evaluate the role of Reg I in NSAID-induced small intestinal injuries. First, to examine the effect of Reg I deficiency on such injuries, indomethacin, a widely used NSAID, was injected subcutaneously into 10-wk-old male Reg I-knockout (Reg I(-/-)) and wild-type (Reg I(+/+)) mice twice with an interval of 24 h, after which the mice were euthanized. Small intestinal injuries were assessed by gross findings, histopathology, and contents of IL-1beta and MPO in the experimental tissues. Next, we investigated the therapeutic potential of Reg I in indomethacin-induced small intestinal injuries. Recombinant Reg I protein (rReg I) was administered to 10-wk-old male ICR mice, then indomethacin was administered 6 h using the same protocol as noted above, after which small intestinal injuries were assessed after euthanasia. Our results showed that Reg I(-/-) mice had a greater number of severe small intestinal lesions after indomethacin administration. Histological examinations of the small intestines from those mice revealed deep ulcers with prominent inflammatory cell infiltration, whereas the mucosal content of proinflammatory agents was also significantly increased. In addition, rReg I administration inhibited indomethacin-induced small intestinal injuries in ICR mice. In conclusion, Reg I may be useful as a therapeutic agent in NSAID-induced small intestinal injuries.

In vivo evidence for the role of RegI in gastric regeneration: transgenic overexpression of RegI accelerates the healing of experimental gastric ulcers

On the basis of its temporal and spatial pattern of expression during the healing of gastric ulcers, RegI is implied to be a key growth factor governing the gastric progenitor cell proliferation, which is fundamental for reconstruction of the gastric tissue; however, there is no direct in vivo evidence. The aim of this study was to use RegI-transgenic (Tg) mice to test the role of RegI protein in the healing of experimentally induced gastric ulcers. The stomachs from 48 pairs of wild-type (Wt) and Tg littermates were examined for gastric erosions after 24 h of water-immersion stress, or, 6, 12, 18 and 24 h after oral administration of HCl/ethanol. Expression levels of c-fos and c-myc proto-oncogenes were examined over time by real-time reverse transcriptase PCR to assess gastric cell proliferation. Almost all the littermate pairs tested showed superiority of Tg mice over Wt mice in the ability of decreasing ulcer index (UI) (cumulative length of erosion). The time-course study revealed that the UIs of Tg were lower in the healing phase, and not in the injury phase. The fraction of proliferating cells was higher in Tg mice than in Wt mice throughout the time course as assessed by c-fos expression levels. This is the first in vivo evidence that RegI has a role in gastric ulcer healing. We suggest that RegI exerts its effects by promoting growth and not by cytoprotection.

Involvement of the IL-22/REG Ialpha axis in ulcerative colitis

The Regenerating gene (REG) Ialpha protein, a trophic and/or anti-apoptotic factor, is important in the pathophysiology of gastrointestinal inflammation. Interleukin (IL)-22 is a recently identified cytokine that is suggested to have pivotal roles in inflammatory bowel diseases. We therefore investigated the involvement of the IL-22/REG Ialpha axis and examined the mechanism of regulation of REG Ialpha expression by IL-22 stimulation in ulcerative colitis (UC) mucosa. Expression of IL-22, IL-22 receptor 1 (IL-22R1), and REG Ialpha in UC mucosa was analyzed by real-time RT-PCR and immunohistochemistry. The effects of IL-22 on REG Ialpha protein expression were examined using a small-interfering RNA for STAT3, an MAPK inhibitor or a PI3K inhibitor. The element responsible for IL-22-induced REG Ialpha promoter activation was determined by a promoter deletion and electrophoretic mobility shift assay. The expression of IL-22 was enhanced in infiltrating inflammatory cells, and that of IL-22R1 and REG Ialpha was concurrently enhanced in the inflamed epithelium in UC mucosa. The levels of REG Ialpha and IL-22 mRNA expression were strongly correlated, and the distributions of REG Ialpha- and IL-22R1-positive epithelial cells were very similar. IL-22 simulation enhanced the expression of REG Ialpha protein through STAT3 tyrosine phosphorylation in colon cancer cells. The IL-22-responsive element was located between -142 and -134 in the REG Ialpha promoter region. REG Ialpha protein may have a pathophysiological role as a biological mediator for immune cell-derived IL-22 in the UC mucosa.

Regenerating gene I regulates interleukin-6 production in squamous esophageal cancer cells

Regenerating gene (REG) I plays important roles in cancer cell biology. The purpose of this study was to determine whether REG I affects cytokine production in cancer cells. We transfected TE-5 and TE-9 squamous esophageal cancer cells with REG Ialpha and Ibeta and examined its effects on cytokine expression. We found that transfecting TE-5 and TE-9 cells with REG I Ialpha and Ibeta led to significantly increased expression of interleukin (IL)-6 mRNA and protein, but it had little or no effect on expression of IL-2, IL-4, IL-5, IL-10, IL-12, IL-13, IL-17A, interferon-gamma, tumor necrosis factor-alpha, granulocyte-colony stimulating factor or transforming growth factor-beta1. The elevated IL-6 expression seen in REG Ialpha transfectants was silenced by small interfering RNA-mediated knockdown. These finding suggest that REG I may act through IL-6 to exert effects on squamous esophageal cancer cell biology.

Loss of RegI in conjunction with gastrin deficiency in mice facilitates efficient gastric ulcer healing but is dispensable for hyperplasia and tumourigenesis

RegI (Regenerating islet derived-1) was originally characterized as a growth factor involved in pancreatic islet cell regeneration. It is also considered a gastrointestinal mitogen as its expression is increased during pathologies involving aberrant cell proliferation that can lead to neoplasia. However, the absolute requirement for RegI to directly stimulate gastric mucosal cell proliferation in vivo requires further investigation. We used RegI-deficient mice to determine the requirement for RegI in normal gastric mucosal development, wound healing, hyperplasia and tumourigenesis. We found that epithelial repair of acetic acid ulcers in compound mutant RegI/gastrin-deficient mice was significantly reduced compared to wild type, RegI-deficient or gastrin-deficient mice. In contrast, RegI was dispensable for normal gastric mucosal development, hyperplasia in HKbeta-deficient mice and tumourigenesis in gp130(F/F) mice. Although RegI was not required for proliferation in these pathological models, expression of multiple Reg family members were increased during gp130(F/F) tumourigenesis. Interestingly, loss of RegI in gp130(F/F) mice resulted in decreased expression of other Reg family members. Our results indicate that RegI and gastrin may synergistically regulate gastric mucosal proliferation during certain pathological settings like wound healing while gastric epithelial proliferation in other pathologies may require coordinated expression of multiple Reg genes.

Advances in RegIV and alimentary system neoplasms

RegIV, a novel member of regenerating gene family, is located at 1p12-13.1, encoding a 17-kDa secreted protein, which is constitutively expressed in the epithelium of normal pancreas and gastrointestinal tract, whereas the expression is up-regulated in inflammatory or neoplastic tissues. RegIV is involved in the carcinogenesis, progression, metastasis and drug resistance of alimentary system neoplasms, and is thought to be useful to make a forecast of the prognosis. It may serve as a new important target for the prevention, diagnosis and treatment of gastrointestinal neoplasms.

Cytokine signalling by gp130 regulates gastric mucosal healing after ulceration and, indirectly, antral tumour progression

The cytokines IL-6 and IL-11, which signal via the receptor gp130, have been implicated in various gut pathologies, including inflammation and wound healing. We used mouse cytokine signalling mutants to evaluate the role of gp130 pathways in gastric ulceration and healing and the effect of spatially remote fundic ulceration on antral tumour progression, since compromised wound healing may impact tumourigenesis. Glacial acetic acid applied to the serosal surface of stomachs from wild-type, gp130(757FF), IL-6(-/-) and IL-11 receptor (R)alpha(-/-) mice was used to induce discrete haemostasis/necrosis and resultant mucosal ulceration. Wound pathology and mRNA expression of key cytokine target genes were examined 2 and 14 weeks after ulcer induction. The outcome of fundic ulceration on antral tumour development in gp130(757FF) mice was also examined. Chemical haemostasis in gp130(7575FF) mice produces more severe gastric ulcers than in wild-type mice. Lack of IL-6 produces more severe ulceration, while loss of IL-11Ralpha less severe ulcers, suggesting a role for IL-11 in ulcer induction. Increased expression of ulcer-associated IL-11 and its established mitogenic target genes RegI, IIIbeta and IIIgamma paralleled severe ulceration in gp130(757FF) mice. In this model, coincident with fundic ulceration, antral tumour development was inhibited and correlated with decreased RegI, IIIbeta and IIIgamma and reduced MMP9 and 13 expression. IL-11-driven transcription via gp130 contributes to the gastric mucosal response to ulceration. Fundic mucosal ulceration modulates antral growth factor and metalloproteinase gene expression, thereby contributing to restricted tumour growth.

Expression and localization of regenerating gene I in a rat liver regeneration model

Regenerating gene (Reg) I has been identified as a regenerative/proliferative factor for pancreatic islet cells. We examined Reg I expression in the regenerating liver of a rat model that had been administered 2-acetylaminofluorene and treated with 70% partial hepatectomy (2-AAF/PH model), where hepatocyte and cholangiocyte proliferation was suppressed and the hepatic stem cells and/or hepatic progenitor cells were activated. In a detailed time course study of activation of hepatic stem cells in the 2-AAF/PH model, utilizing immunofluorescence staining with antibodies of Reg I and other cell-type-specific markers, we found that Reg I-expressing cells are present in the bile ductules and increased during regeneration. Reg I-expressing cells were colocalized with CK19, OV6, and AFP. These results demonstrate that Reg I is significantly upregulated in the liver of the 2-AAF/PH rat model, accompanied by the formation of bile ductules during liver regeneration.

REG I enhances chemo- and radiosensitivity in squamous cell esophageal cancer cells

Identification of reliable markers of chemo- and radiosensitivity and the key molecules that enhance the susceptibility of squamous esophageal cancer cells to anticancer treatments would be highly desirable. To test whether regenerating gene (REG) I expression enhances chemo- and radiosensitivity in esophageal squamous cell carcinoma cells, we used MTT (3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide) assays to compare the chemo- and radiosensitivities of untransfected TE-5 and TE-9 cells with those of cells stably transfected with REG Ialpha and Ibeta. We then used flow cytometry to determine whether REG I expression alters cell cycle progression. No REG I mRNA or protein were detected in untransfected TE-5 and TE-9 cells. Transfection with REG Ialpha and Ibeta led to strong expression of both REG I mRNA and protein in TE-5 and TE-9 cells, which in turn led to significant increases in both chemo- and radiosensitivity. Cell cycle progression was unaffected by REG I expression. REG I thus appears to enhance the chemo- and radiosensitivity of squamous esophageal cancer cells, which suggests that it may be a useful target for improved and more individualized treatments for patients with esophageal squamous cell carcinoma.

Advances in regenerating gene family and digestive system neoplasms

Since the first member of regenerating gene (Reg) family was discovered in 1988, it has been verified that regenerating genes play important roles in diabetes, inflammation and injury, and digestive system tumors. Now, more members of Reg family have been cloned. With further investigations, the great role of Reg family, especially Reg IV, in digestive system neoplasms has attracted more and more attention.

Three genes control the timing, the site and the size of blastema formation in Drosophila

Regeneration is a vital process to maintain and repair tissues. Despite the importance of regeneration, the genes responsible for regenerative growth remain largely unknown. In Drosophila, imaginal disc regeneration can be induced either by fragmentation and in vivo culture or in situ by ubiquitous expression of wingless (wg/wnt1). Imaginal discs, like appendages in lower vertebrates, initiate regeneration by wound healing and proliferation at the wound site, forming a regeneration blastema. Most blastema cells maintain their disc-specific identity during regeneration; a few cells however, exhibit stem-cell like properties and switch to a different fate, in a phenomenon known as transdetermination. We identified three genes, regeneration (rgn), augmenter of liver regeneration (alr) and Matrix metalloproteinase-1 (Mmp1) expressed specifically in blastema cells during disc regeneration. Mutations in these genes affect both fragmentation- and wg-induced regeneration by either delaying, reducing or positioning the regeneration blastema. In addition to the modifications of blastema homeostasis, mutations in the three genes alter the rate of regeneration-induced transdetermination. We propose that these genes function in regenerative proliferation, growth and regulate cellular plasticity.

REG Ialpha is a reliable marker of chemoradiosensitivity in squamous cell esophageal cancer patients

BACKGROUND

A reliable marker of chemoradiosensitivity that would enable appropriate and individualized treatment of thoracic squamous cell esophageal cancer has long been sought. We investigated whether regenerating gene (REG) Ialpha is such a marker.

METHODS

We assessed expression of REG Ialpha in untreated endoscopic biopsy specimens and examined the correlation between REG Ialpha expression and the clinical responses to definitive chemoradiotherapy and prognosis. We also examined the relationship between REG Ialpha expression in the resected tumor and the prognosis of patients who received esophagectomy for thoracic squamous cell esophageal cancer.

RESULTS

Among the 42 patients treated with definitive chemoradiotherapy, 8 of the 23 REG I-positive patients (35%) showed complete responses to chemoradiotherapy, while only one of the 19 REG I-negative patients did so. The survival rate among the REG I-positive patients was significantly better than among the REG I-negative patients. For the 76 patients treated surgically, there was no significant difference in the survival rates among the REG I-positive and REG I-negative patients.

CONCLUSIONS

REG Ialpha expression in squamous cell esophageal carcinoma may be a reliable marker of chemoradiosensitivity. We anticipate that it will enable us to provide more appropriate and individualized treatment to patients of advanced esophageal squamous cell carcinoma.

Chronically administered retinoic acid has trophic effects in the rat small intestine and promotes adaptation in a resection model of short bowel syndrome

Following the loss of functional small bowel surface area, the intestine undergoes a compensatory adaptive response. The observation that adaptation is inhibited in vitamin A-deficient rats following submassive intestinal resection suggested that vitamin A is required for this response and raised the possibility that exogenous vitamin A could augment adaptation. Therefore, to directly assess whether chronically administered retinoic acid could stimulate gut adaptation in a model of short bowel syndrome and to address the mechanisms of any such effects, Sprague-Dawley rats were implanted with controlled release retinoic acid or control pellets and then subjected to mid-small bowel or sham resections. At 2 wk postoperation, changes in gut morphology, crypt cell proliferation and apoptosis, enterocyte migration, the extracellular matrix, and gene expression were assessed. Retinoic acid had significant trophic effects in resected and sham-resected rats. Retinoic acid markedly inhibited apoptosis and stimulated crypt cell proliferation and enterocyte migration postresection. Data presented indicate that these proadaptive effects of retinoic acid may be mediated via changes in the extracellular matrix (e.g., by increasing collagen IV synthesis, decreasing E-cadherin expression, and reducing integrin beta(3) levels), via affects on Hedgehog signaling (e.g., by reducing expression of the Hedgehog receptors Ptch and Ptch2 and the Gli1 transcription factor), by increasing expression of Reg1 and Pap1, and by modulation of retinoid and peroxisome proliferator-activated receptor signaling pathways. These studies are the first to demonstrate that retinoic acid can significantly enhance intestinal adaptation and suggest it may be beneficial in patients with short bowel syndrome.