Tumor epithelial cells develop within a microenvironment consisting of extracellular matrix, growth factors, and cytokines produced by nonepithelial stromal cells. In response to paracrine signals from tumor epithelia, stromal cells modify the microenvironment to promote tumor growth and metastasis. Here, we identify interleukin 33 (IL-33) as a regulator of tumor stromal cell activation and mediator of intestinal polyposis. In human colorectal cancer, IL-33 expression was induced in the tumor epithelium of adenomas and carcinomas, and expression of the IL-33 receptor, IL1RL1 (also referred to as IL1-R4 or ST2), localized predominantly to the stroma of adenoma and both the stroma and epithelium of carcinoma. Genetic and antibody abrogation of responsiveness to IL-33 in the Apc Min/+ mouse model of intestinal tumorigenesis inhibited proliferation, induced apoptosis, and suppressed angiogenesis in adenomatous polyps, which reduced both tumor number and size. Similar to human adenomas, IL-33 expression localized to tumor epithelial cells and expression of IL1RL1 associated with two stromal cell types, subepithelial myofibroblasts and mast cells, in Apc Min/+ polyps. In vitro, IL-33 stimulation of human subepithelial myofibroblasts induced the expression of extracellular matrix components and growth factors associated with intestinal tumor progression. IL-33 deficiency reduced mast cell accumulation in Apc Min/+ polyps and suppressed the expression of mast cell-derived proteases and cytokines known to promote polyposis. Based on these findings, we propose that IL-33 derived from the tumor epithelium promotes polyposis through the coordinated activation of stromal cells and the formation of a protumorigenic microenvironment.IL-33 | colorectal cancer | ApcMin | wound healing | Th2 immunity

BackgroundThe International Mouse Phenotyping Consortium is generating null allele mice for every protein-coding gene in the genome and characterizing these mice to identify gene–phenotype associations. While CRISPR/Cas9-mediated null allele production in mice is highly efficient, generation of conditional alleles has proven to be more difficult. To test the feasibility of using CRISPR/Cas9 gene editing to generate conditional knockout mice for this large-scale resource, we employed Cas9-initiated homology-driven repair (HDR) with short and long single stranded oligodeoxynucleotides (ssODNs and lssDNAs).ResultsUsing pairs of single guide RNAs and short ssODNs to introduce loxP sites around a critical exon or exons, we obtained putative conditional allele founder mice, harboring both loxP sites, for 23 out of 30 targeted genes. LoxP sites integrated in cis in at least one mouse for 18 of 23 genes. However, loxP sites were mutagenized in 4 of the 18 in cis lines. HDR efficiency correlated with Cas9 cutting efficiency but was minimally influenced by ssODN homology arm symmetry. By contrast, using pairs of guides and single lssDNAs to introduce loxP-flanked exons, conditional allele founders were generated for all four genes targeted, although one founder was found to harbor undesired mutations within the lssDNA sequence interval. Importantly, when employing either ssODNs or lssDNAs, random integration events were detected.ConclusionsOur studies demonstrate that Cas9-mediated HDR with pairs of ssODNs can generate conditional null alleles at many loci, but reveal inefficiencies when applied at scale. In contrast, lssDNAs are amenable to high-throughput production of conditional alleles when they can be employed. Regardless of the single-stranded donor utilized, it is essential to screen for sequence errors at sites of HDR and random insertion of donor sequences into the genome.Electronic supplementary materialThe online version of this article (10.1186/s12915-018-0529-0) contains supplementary material, which is available to authorized users.

The identification of causal variants in sequencing studies remains a considerable challenge that can be partially addressed by new gene-specific knowledge. Here, we integrate measures of how essential a gene is to supporting life, as inferred from viability and phenotyping screens performed on knockout mice by the International Mouse Phenotyping Consortium and essentiality screens carried out on human cell lines. We propose a cross-species gene classification across the Full Spectrum of Intolerance to Loss-of-function (FUSIL) and demonstrate that genes in five mutually exclusive FUSIL categories have differing biological properties. Most notably, Mendelian disease genes, particularly those associated with developmental disorders, are highly overrepresented among genes non-essential for cell survival but required for organism development. After screening developmental disorder cases from three independent disease sequencing consortia, we identify potentially pathogenic variants in genes not previously associated with rare diseases. We therefore propose FUSIL as an efficient approach for disease gene discovery.

Although genomic sequencing has been transformative in the study of rare genetic diseases, identifying causal variants remains a considerable challenge that can be addressed in part by new gene-specific knowledge. Here, we integrate measures of how essential a gene is to supporting life, as inferred from the comprehensive viability and phenotyping screens performed on knockout mice by the International Mouse Phenotyping Consortium and from human cell line essentiality screens. We propose a novel, cross-species gene classification across the Full

Breast cancer stem cells, the root of tumor growth, present challenges to investigate: Primary human breast cancer cells are difficult to establish in culture and inconsistently yield tumors after transplantation into immune-deficient recipient mice. Furthermore, there is limited characterization of mammary cancer stem cells in mice, the ideal model for the study of breast cancer. We herein describe a pre-clinical breast cancer stem cell model, based on the properties of cancer stem cells, derived from transgenic MMTV-PyMT mice. Using a defined set of cell surface markers to identify cancer stem cells by flow cytometry, at least four cell populations were recovered from primary mammary cancers. Only two of the four populations, one epithelial and one mesenchymal, were able to survive and proliferate in vitro. The epithelial population exhibited tumor initiation potential with as few as 10 cells injected into syngeneic immune-competent recipients. Tumors initiated from injected cell lines recapitulated the morphological and physiological components of the primary tumor. To highlight the stemness potential of the putative cancer stem cells, B lymphoma Mo-MLV insertion region 1 homolog (Bmi-1) expression was knocked down via shRNA targeting Bmi-1. Without Bmi-1 expression, putative cancer stem cells could no longer initiate tumors, but tumor initiation was rescued with the introduction of a Bmi-1 overexpression vector in the Bmi-1 knockdown cells. In conclusion, our data show that primary mammary cancers from MMTV-PyMT mice contain putative cancer stem cells that survive in culture and can be used to create a model for study of mammary cancer stem cells.

Testicular teratomas result from anomalies in embryonic germ cell development. In 129 inbred mice, teratoma initiation coincides with germ cell sex-specific differentiation and the mitotic-meiotic switch: XX and XY germ cells repress pluripotency, XX germ cells initiate meiosis, and XY germ cells activate male-specific differentiation and mitotic arrest. Here, we report that expression of , a gene that is crucial to male sex specification, is delayed in teratoma-susceptible germ cells. Decreased expression of was found to be due, in part, to the allele present in 129 mice. In teratoma-susceptible germ cells, diminished expression of genes downstream of disrupted processes that were crucial to male germ cell differentiation. Deficiency for increased teratoma incidence in 129 mice and induced developmental abnormalities associated with tumor initiation in teratoma-resistant germ cells. Finally, in the absence of commitment to the male germ cell fate, we discovered that a subpopulation of teratoma-susceptible germ cells transition into embryonal carcinoma (EC) cells with primed pluripotent features. We conclude that delayed male germ cell sex-specification facilitates the transformation of germ cells with naïve pluripotent features into primed pluripotent EC cells.

Summary The promyelocytic leukemia zinc finger (PLZF) transcription factor mediates a wide‐range of biological processes. Accordingly, perturbation of PLZF function results in a myriad of physiologic defects, the most conspicuous of which is abnormal skeletal patterning. Although whole body knockout of Plzf in the mouse (Plzf KO) has significantly expanded our understanding of Plzf function in vivo, a conditional knockout mouse model that enables tissue or cell‐type specific ablation of Plzf has not been developed. Therefore, we used CRISPR/Cas 9 gene editing to generate a mouse model in which exon 2 of the murine Plzf gene is specifically flanked (or floxed) by LoxP sites (Plzf f/f). Crossing our Plzf f/f mouse with a global cre‐driver mouse to generate the Plzf d/d bigenic mouse, we demonstrate that exon 2 of the Plzf gene is ablated in the Plzf d/d bigenic. Similar to the previously reported Plzf KO mouse, the Plzf d/d mouse exhibits a severe defect in skeletal patterning of the hindlimb, indicating that the Plzf f/f mouse functions as designed. Therefore, studies in this short technical report demonstrate that the Plzf f/f mouse will be useful to investigators who wish to explore the role of the Plzf transcription factor in a specific tissue or cell‐type.

Testicular teratomas result from anomalies in embryonic germ cell development. In the 129 family of inbred mouse strains, teratomas arise during the same developmental period that male germ cells normally enter G1/G0 mitotic arrest and female germ cells initiate meiosis (the mitotic:meiotic switch). Dysregulation of this switch associates with teratoma susceptibility and involves three germ cell developmental abnormalities seemingly critical for tumor initiation: delayed G1/G0 mitotic arrest, retention of pluripotency, and misexpression of genes normally restricted to embryonic female and adult male germ cells. One misexpressed gene, cyclin D1 (Ccnd1), is a known regulator of cell cycle progression and an oncogene in many tissues. Here, we investigated whether Ccnd1 misexpression in embryonic germ cells is a determinant of teratoma susceptibility in mice. We found that CCND1 localizes to teratomasusceptible germ cells that fail to enter G1/G0 arrest during the mitotic:meiotic switch and is the only Dtype cyclin misexpressed during this critical developmental time frame. We discovered that Ccnd1 deficiency in teratoma-susceptible mice significantly reduced teratoma incidence and suppressed the germ cell proliferation and pluripotency abnormalities associated with tumor initiation. Importantly, Ccnd1 expression was dispensable for somatic cell development and male germ cell specification and maturation in tumor-susceptible mice, implying that the mechanisms by which Ccnd1 deficiency reduced teratoma incidence were germ cell autonomous and specific to tumorigenesis. We conclude that misexpression of Ccnd1 in male germ cells is a key component of a larger pro-proliferative program that disrupts the mitotic:meiotic switch and predisposes 129 inbred mice to testicular teratocarcinogenesis.