Bone morphogenetic protein 2 induced differentiation toward superficial epithelial cells in the gastric mucosa

Dysplastic crypt-rings in tandem: A novel histologic parameter in tubular adenomas

Descriptions of the various dysplastic crypt phenotypes occurring in TA have remained unattended in the literature. Recently, new crypt-phenotypes, characterized by crypt rings in tandem (CRT), and by dysplastic crypt rings in tandem (DCRT) were described in IBD, and in in IBD-associated dysplasia, respectively. Here, we report the occurrence of DCRT in 40.4 % (n = 59) out of 146 consecutive tubular adenomas of the colorectum (TA). The number of DCRT varied: 10 TA had two DCRT, seven TA had three DCRT, two TA, four DCRT and the remaining two TA had ≥ five DCRT. The frequency of DCRT was influenced by TA-size; larger TA (≥ 5 mm) had significantly more DCRT than smaller TA (<5 mm). Conversely, the frequency of TA with DCRT was not influenced by age, gender, or localization. Since only 1 or 2 sections were available per TA, the number of DCRT in the entire TA should be higher than those shown in Results. Historical controls in human and rodent normal colorectum showed no CRT. Moreover, DCRT were not found in 781 historical non-polypoid colorectal adenomas. The present finding might encourage searching for DCRT, the final goal being to achieve a more elaborated microscopic narrative of TA, the most prevalent of all colorectal adenomas.

Exploring the Regulators of Keratinization: Role of BMP-2 in Oral Mucosa

The oral mucosa functions as a physico-chemical and immune barrier to external stimuli, and an adequate width of the keratinized mucosa around the teeth or implants is crucial to maintaining them in a healthy and stable condition. In this study, for the first time, bulk RNA-seq analysis was performed to explore the gene expression of laser microdissected epithelium and lamina propria from mice, aiming to investigate the differences between keratinized and non-keratinized oral mucosa. Based on the differentially expressed genes (DEGs) and Gene Ontology (GO) Enrichment Analysis, bone morphogenetic protein 2 (BMP-2) was identified to be a potential regulator of oral mucosal keratinization. Monoculture and epithelial-mesenchymal cell co-culture models in the air-liquid interface (ALI) indicated that BMP-2 has direct and positive effects on epithelial keratinization and proliferation. We further performed bulk RNA-seq of the ALI monoculture stimulated with BMP-2 in an attempt to identify the downstream factors promoting epithelial keratinization and proliferation. Analysis of the DEGs identified, among others, IGF2, ID1, LTBP1, LOX, SERPINE1, IL24, and MMP1 as key factors. In summary, these results revealed the involvement of a well-known growth factor responsible for bone development, BMP-2, in the mechanism of oral mucosal keratinization and proliferation, and pointed out the possible downstream genes involved in this mechanism.

Crypt-rings in tandem detected in infectious colitis, in IBD and in IBD-associated noninvasive neoplasia

AIMS

Recently, eight novel histologic structures in colon mucosa with inflammation were described. Here, we assessed the frequency of one of them: crypt rings in tandem (CRT), in patients with infectious colitis (IC), IBD (ulcerative colitis; UC or Crohn colitis; CrC) and UC in remission (UCR). In addition, the frequency of dysplastic CRT (DCRT) in IBD-associated noninvasive neoplasia (IBDNIN) were also calculated.

METHODS

Colon biopsies in 578 cases were reviewed: 42 cases with IC, 280 with IBD (180 UC and 100 CrC), 100 UCR and the remaining 156, IBDNIN.

RESULTS

The proportions of CRT in IC was 16.7%, in IBD 14.3% %, in UCR 3%, and of DCRT in IBDNIN, 20%. No differences were recorded between the proportions of CRT in IC, UC and CrC. Conversely, the difference in CRT frequency between UC and UCR, and between CRT and DCRT were significant (P = 0.006, and p = 0.05, respectively).

CONCLUSIONS

CRT evolved in IC and in IBD. The finding of CRT in IC strongly suggest that those characteristic crypts were shaped at the early stages of mucosal inflammation. CRT persisted in IBD with protracted inflammation but plummeted in UCR, that is when the mucosal inflammation waned. The proportion of DCRT was significantly higher than that of CRT. It is submitted that DCRT might had developed in IBDNIN using CRT as scaffolds. This is the first study in which a characteristic pathologic aberration of cryptogenesis was tracked in colon biopsies from patients with IBD and with IBD-associated neoplastic transformation.

Regulation of gastric epithelial cell homeostasis by gastrin and bone morphogenetic protein signaling

We reported that transgenic expression of the bone morphogenetic protein (BMP) signaling inhibitor noggin in the mouse stomach, leads to parietal-cell (PC) loss, expansion of transitional cells expressing markers of both mucus neck and zymogenic lineages, and to activation of proliferative mechanisms. Because these cellular changes were associated with increased levels of the hormone gastrin, we investigated if gastrin mediates the expression of the phenotypic changes of the noggin transgenic mice (NogTG mice). Three-month-old NogTG mice were crossed to gastrin-deficient (GasKO mice) to generate NogTG;GasKO mice. Morphology of the corpus of wild type, NogTG, GasKO, and NogTG;GasKO mice was analyzed by H&E staining. Distribution of PCs and zymogenic cells (ZCs) was analyzed by immunostaining for the H⁺/K⁺-ATPase and intrinsic factor (IF). Expression of the H⁺/K⁺-ATPase and IF genes and proteins were measured by QRT-PCR and western blots. Cell proliferation was assessed by immunostaining for proliferating cell nuclear antigen. The corpus of the NogTG;GasKO mice displayed a marked reduction in the number of PCs and ZCs in comparison to NogTG mice. Further, cellular proliferation was significantly lower in NogTG;GasKO mice, than in the NogTG mice. Thus, gastrin mediates the increase in gastric epithelial cell proliferation induced by inhibition of BMP signaling in vivo. Moreover, gastrin and BMP signaling exert cooperative effects on the maturation and differentiation of both the zymogenic and PC lineages. These findings contribute to a better understanding of the factors involved in the control of gastric epithelial cell homeostasis.

Anti-inflammatory activity of bone morphogenetic protein signaling pathways in stomachs of mice

BACKGROUND & AIMS

Bone morphogenetic protein (BMP)4 is a mesenchymal peptide that regulates cells of the gastric epithelium. We investigated whether BMP signaling pathways affect gastric inflammation after bacterial infection of mice.

METHODS

We studied transgenic mice that express either the BMP inhibitor noggin or the β- galactosidase gene under the control of a BMP-responsive element and BMP4(βgal/+) mice. Gastric inflammation was induced by infection of mice with either Helicobacter pylori or Helicobacter felis. Eight to 12 weeks after inoculation, gastric tissue samples were collected and immunohistochemical, quantitative, reverse-transcription polymerase chain reaction and immunoblot analyses were performed. We used enzyme-linked immunosorbent assays to measure cytokine levels in supernatants from cultures of mouse splenocytes and dendritic cells, as well as from human gastric epithelial cells (AGS cell line). We also measured the effects of BMP-2, BMP-4, BMP-7, and the BMP inhibitor LDN-193189 on the expression of interleukin (IL)8 messenger RNA by AGS cells and primary cultures of canine parietal and mucus cells. The effect of BMP-4 on NFkB activation in parietal and AGS cells was examined by immunoblot and luciferase assays.

RESULTS

Transgenic expression of noggin in mice increased H pylori- or H felis-induced inflammation and epithelial cell proliferation, accelerated the development of dysplasia, and increased expression of the signal transducer and activator of transcription 3 and activation-induced cytidine deaminase. BMP-4 was expressed in mesenchymal cells that expressed α-smooth muscle actin and activated BMP signaling pathways in the gastric epithelium. Neither BMP-4 expression nor BMP signaling were detected in immune cells of C57BL/6, BRE-β-galactosidase, or BMP-4(βgal/+) mice. Incubation of dendritic cells or splenocytes with BMP-4 did not affect lipopolysaccharide-stimulated production of cytokines. BMP-4, BMP-2, and BMP-7 inhibited basal and tumor necrosis factor α-stimulated expression of IL8 in canine gastric epithelial cells. LDN-193189 prevented BMP4-mediated inhibition of basal and tumor necrosis factor α-stimulated expression of IL8 in AGS cells. BMP-4 had no effect on TNFα-stimulated phosphorylation and degradation of IκBα, or on TNFα induction of a NFκβ reporter gene.

CONCLUSIONS

BMP signaling reduces inflammation and inhibits dysplastic changes in the gastric mucosa after infection of mice with H pylori or H felis.

Cooperativity of E-cadherin and Smad4 loss to promote diffuse-type gastric adenocarcinoma and metastasis

Loss of E-cadherin (CDH1), Smad4, and p53 has been shown to play an integral role in gastric, intestinal, and breast cancer formation. Compound conditional knockout mice for Smad4, p53, and E-cadherin were generated to define and compare the roles of these genes in gastric, intestinal, and breast cancer development by crossing with Pdx-1-Cre, Villin-Cre, and MMTV-Cre transgenic mice. Interestingly, gastric adenocarcinoma was significantly more frequent in Pdx-1-Cre;Smad4(F/F);Trp53(F/F);Cdh1(F) (/+) mice than in Pdx-1-Cre;Smad4(F/F);Trp53(F/F);Cdh1(+/+) mice, demonstrating that Cdh1 heterozygosity accelerates the development and progression of gastric adenocarcinoma, in combination with loss of Smad4 and p53. Pdx-1-Cre;Smad4(F/F);Trp53(F/F);Cdh1(F) (/+) mice developed gastric adenocarcinomas without E-cadherin expression. However, intestinal and mammary adenocarcinomas with the same genetic background retained E-cadherin expression and were phenotypically similar to mice with both wild-type Cdh1 alleles. Lung metastases were identified in Pdx-1-Cre;Smad4(F/F);Trp53(F/F);Cdh1(F) (/+) mice, but not in the other genotypes. Nuclear β-catenin accumulation was identified at the invasive tumor front of gastric adenocarcinomas arising in Pdx-1-Cre;Smad4(F/F);Trp53(F/F);Cdh1(F) (/+) mice. This phenotype was less prominent in mice with intact E-cadherin or Smad4, indicating that the inhibition of β-catenin signaling by E-cadherin or Smad4 downregulates signaling pathways involved in metastases in Pdx-1-Cre;Smad4(F/F);Trp53(F/F);Cdh1(F) (/+) mice. Knockdown of β-catenin significantly inhibited the migratory activity of Pdx-1-Cre;Smad4(F/F);Trp53(F/F);Cdh1(F) (/+) cell lines. Thus, loss of E-cadherin and Smad4 cooperates with p53 loss to promote the development and metastatic progression of gastric adenocarcinomas, with similarities to human gastric adenocarcinoma.

IMPLICATIONS

This study demonstrates that inhibition of β-catenin is a converging node for the antimetastatic signaling pathways driven by E-cadherin and Smad4 in Pdx-1-Cre;Smad4(F/F);Trp53(F/F);Cdh1(F) (/+) mice, providing novel insights into mechanisms for gastric cancer metastasis.

MAPKs and signal transduction in the control of gastrointestinal epithelial cell proliferation and differentiation

Mitogen-activated protein kinase (MAPK) pathways are activated by several stimuli and transduce the signal inside cells, generating diverse responses including cell proliferation, differentiation, migration and apoptosis. Each MAPK cascade comprises a series of molecules, and regulation takes place at different levels. They communicate with each other and with additional pathways, creating a signaling network that is important for cell fate determination. In this review, we focus on ERK, JNK, p38 and ERK5, the major MAPKs, and their interactions with PI3K-Akt, TGFβ/Smad and Wnt/β-catenin pathways. More importantly, we describe how MAPKs regulate cell proliferation and differentiation in the rapidly renewing epithelia that lines the gastrointestinal tract and, finally, we highlight the recent findings on nutritional aspects that affect MAPK transduction cascades.

Bone morphogenetic protein signaling regulates gastric epithelial cell development and proliferation in mice

BACKGROUND & AIMS

We investigated the role of bone morphogenetic protein (BMP) signaling in the regulation of gastric epithelial cell growth and differentiation by generating transgenic mice that express the BMP inhibitor noggin in the stomach.

METHODS

The promoter of the mouse H+/K+-ATPase β-subunit gene, which is specifically expressed in parietal cells, was used to regulate expression of noggin in the gastric epithelium of mice. The transgenic mice were analyzed for noggin expression, tissue morphology, cellular composition of the gastric mucosa, gastric acid content, and plasma levels of gastrin. Tissues were analyzed by immunohistochemical, quantitative real-time polymerase chain reaction, immunoblot, microtitration, and radioimmunoassay analyses.

RESULTS

In the stomachs of the transgenic mice, phosphorylation of Smad 1, 5, and 8 decreased, indicating inhibition of BMP signaling. Mucosa were of increased height, with dilated glands, cystic structures, reduced numbers of parietal cells, and increased numbers of cells that coexpressed intrinsic factor, trefoil factor 2, and Griffonia (Bandeiraea) simplicifolia lectin II, compared with wild-type mice. In the transgenic mice, levels of the H+/K+-ATPase α-subunit protein and messenger RNA were reduced, whereas those of intrinsic factor increased. The transgenic mice were hypochloridric and had an increased number of Ki67- and proliferating cell nuclear antigen-positive cells; increased levels of plasma gastrin; increased expression of transforming growth factor-α, amphiregulin, and gastrin; and activation of extracellular signal-regulated kinase 2.

CONCLUSIONS

Inhibiting BMP signaling in the stomachs of mice by expression of noggin causes loss of parietal cells, development of transitional cells that express markers of mucus neck and zymogenic lineages, and activation of proliferation. BMPs are therefore important regulators of gastric epithelial cell homeostasis.

Novel regulatory aspects of the extracellular Ca2+-sensing receptor, CaR

The capacity to sense and adapt to changes in environmental cues is of paramount importance for every living organism. From yeast to man, cells must be able to match cellular activities to growth environment and nutrient availability. Key to this process is the development of membrane-bound systems that can detect modifications in the extracellular environment and to translate these into biological responses. Evidence gathered over the last 15 years has demonstrated that many of these cell surface "sensors" belong to the G protein-coupled receptor superfamily. Crucial to our understanding of nutrient sensing in mammalian species has been the identification of the extracellular Ca(2+)/cation-sensing receptor, CaR. CaR was the first ion-sensing molecule identified in man and genetic studies in humans have revealed the importance of the CaR in mineral ion metabolism. Latter, it has become apparent that the CaR also plays an important role outside the Ca(2+) homeostatic system, as an integrator of multiple environmental signals for the regulation of many vital cellular processes, from cell-to-cell communication to secretion and cell survival/cell death. Recently, novel aspects of receptor function reveal an unexpected role for the CaR in the regulation of growth and development in utero.