Bacterial clade-specific analysis identifies distinct epithelial responses in inflammatory bowel disease.

Abnormal immune responses to the resident gut microbiome can drive inflammatory bowel disease (IBD). Here, we combine high-resolution, culture-based shotgun metagenomic sequencing and analysis with matched host transcriptomics across three intestinal sites (terminal ileum, cecum, rectum) from pediatric IBD (PIBD) patients (n = 58) and matched controls (n = 42) to investigate this relationship. Combining our site-specific approach with bacterial culturing, we establish a cohort-specific bacterial culture collection, comprising 6,620 isolates (170 distinct species, 32 putative novel), cultured from 286 mucosal biopsies. Phylogeny-based, clade-specific metagenomic analysis identifies key, functionally distinct Enterococcus clades associated with either IBD or health. Strain-specific in vitro validation demonstrates differences in cell cytotoxicity and inflammatory signaling in intestinal epithelial cells, consistent with the colonic mucosa-specific response measured in patients with IBD. This demonstrates the importance of strain-specific phenotypes and consideration of anatomical sites in exploring the dysregulated host-bacterial interactions in IBD.

Ultraviolet-induced apoptosis in embryonic stem cells in vitro.

Embryonic stem (ES) cells, and the inner cell mass from which they are derived, are hypersensitive to DNA damage and appear to have specific cellular defense systems for DNA repair and the elimination of damaged cells. These mechanisms differ from somatic cells and are vital to minimize developmental defects that would potentially result from the continued proliferation and differentiation of abnormal cells into adult cell lineages. Although the DNA damage-induced signaling cascades activated in these cells are known to include p38 and c-Jun N-terminal protein kinase mitogen-activated protein kinase pathways and activation of a variety of transcription factors, including p53, nuclear factor-kappaB, and activator protein-1, the nature of the specific mechanisms unique to these cells remains to be elucidated. Here, we describe the use of homozygous knockout ES cells to investigate the role of Ets1 in the response to DNA damage in these cells. These studies demonstrate that Ets1 is required for optimal p53 function in this response and further demonstrate the potential for knockout ES cells to elucidate the role of specific genes in early embryonic cell responses.

Ets1 as a marker of malignant potential in gastric carcinoma.

AIM: Ets1 proto-oncogene is a transcription factor involved in the activation of several genes of tumor invasion and metastasis. We aimed to determine the relationship between the extent and intensity of Ets1 expression and patients' clinicopathological factors in gastric carcinoma. METHODS: Immunohistochemical analysis was performed for gastric tumor paraffin-embedded sections, followed by image analysis. RESULTS: Ets1 was not expressed in the normal gastric epithelium and its surrounding cells. The percentage of Ets1 expressing cells detected increased significantly in both epithelial tumor and stromal cells from high T classification, lymph node metastasis positive, clinical advanced-stage groups (P<0.001). The level of Ets1 staining in epithelial tumor cells also reflected the degree of cell differentiation. The percentage of epithelial and stromal cells expressing Ets1 was significantly correlated with the presence of lymph node metastasis (P=0.014 and P<0.001 respectively). Ets1 expression was not observed in tissue samples from patients with benign gastric ulcers. CONCLUSION: Ets1 protein expression in epithelial tumor cells reflects the degree of differentiation, and the percentage of Ets1 positive tumor and stromal cells correlates with lymph node metastasis. Thus Ets1 is a valuable marker of malignant potential in terms of invasiveness and metastasis of gastric carcinoma. It is also possible that inhibition of Ets1 is a potential avenue for therapy in gastric cancer.

Comparison of mice born after intracytoplasmic sperm injection with in vitro fertilization and natural mating.

The procedures of in vitro fertilization (IVF) and intracytoplasmic sperm injection (ICSI) are routinely used in modern medicine to overcome infertility and, in animal husbandry, to propagate lines with compromised fertility. However, there remains concern that manual selection and injection of whole sperm into oocytes could contribute to pre- and postnatal developmental defects. To address this, we have used gene expression profiling and immunophenotyping to characterize offspring generated by these procedures. We used gametes from glutathione peroxidase 1 knockout (Gpx1-/-) mice as a sensitized screen responsive to oxidative stress from artificial reproduction technologies (ART). There were no differences between IVF and ICSI derived offspring in gene expression patterns, and minor differences in hematopoietic parameters. Furthermore there were only minor differences between these IVF and ICSI pups and those derived from natural mating. These data demonstrate for the first time in that there is no significant phenotypic affects of ICSI when compared to IVF and we identified a relatively minor influence of the artificial fertilization methods on phenotype of offspring compared with natural mating. These observations would support the use of ICSI for derivation of mutant mouse lines and may be of some importance for the use of this technique in human ART.

Elf5 is essential for early embryogenesis and mammary gland development during pregnancy and lactation.

Elf5 is an epithelial-specific ETS factor. Embryos with a null mutation in the Elf5 gene died before embryonic day 7.5, indicating that Elf5 is essential during mouse embryogenesis. Elf5 is also required for proliferation and differentiation of mouse mammary alveolar epithelial cells during pregnancy and lactation. The loss of one functional allele led to complete developmental arrest of the mammary gland in pregnant Elf5 heterozygous mice. A quantitative mRNA expression study and Western blot analysis revealed that decreased expression of Elf5 correlated with the downregulation of milk proteins in Elf5(+/-) mammary glands. Mammary gland transplants into Rag(-/-) mice demonstrated that Elf5(+/-) mammary alveolar buds failed to develop in an Elf5(+/+) mammary fat pad during pregnancy, demonstrating an epithelial cell autonomous defect. Elf5 expression was reduced in Prolactin receptor (Prlr) heterozygous mammary glands, which phenocopy Elf5(+/-) glands, suggesting that Elf5 and Prlr are in the same pathway. Our data demonstrate that Elf5 is essential for developmental processes in the embryo and in the mammary gland during pregnancy.

A human CD2 minigene directs CRE-mediated recombination in T cells in vivo.

We have produced a mouse line that expresses the Cre recombinase under the regulation of a human CD2 minigene to facilitate Cre-specific recombination in T lymphocytes. These mice express Cre in thymocytes and T cells and are capable of efficient site-specific recombination as shown in the spleen and thymus, but not other tissues. These mice thus provide an excellent resource for the study of gene function during thymocyte development and in mature T cells.

Ets1 is required for p53 transcriptional activity in UV-induced apoptosis in embryonic stem cells.

Embryonic stem (ES) cells contain a p53-dependent apoptosis mechanism to avoid the continued proliferation and differentiation of damaged cells. We show that mouse ES cells lacking Ets1 are deficient in their ability to undergo UV-induced apoptosis, similar to p53 null ES cells. In Ets1(-/-) ES cells, UV induction of the p53 regulated genes mdm2, perp, cyclin G and bax was decreased both at mRNA and protein levels. While p53 protein levels were unaltered in Ets1(-/-) cells, its ability to transactivate genes such as mdm2 and cyclin G was reduced. Furthermore, electrophoretic mobility shift assays and immunoprecipitations demonstrated that the presence of Ets1 was necessary for a CBP/p53 complex to be formed. Chromatin immunoprecipitations demonstrated that Ets1 was required for the formation of a stable p53-DNA complex under physiological conditions and activation of histone acetyltransferase activity. These data demonstrate that Ets1 is an essential component of a UV-responsive p53 transcriptional activation complex in ES cells and suggests that Ets1 may contribute to the specificity of p53-dependent gene transactivation in distinct cellular compartments.