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At least 19 recordsLinked to original sources

Genetic diversity of Collaborative Cross mice implicates FFAR3 as a target for ILC2 anti-inflammatory reprogramming.

Pulmonary group 2 innate lymphoid cells (ILC2s) are key drivers of Type 2 inflammation in diseases like asthma, yet the molecular mechanisms regulating their function are incompletely understood. Using the genetically diverse Collaborative Cross (CC) mouse panel, we mapped a quantitative trait locus (QTL) that governs ILC2 prevalence in the lung after aeroallergen exposure. This QTL induces a large population of ILC2s in the lung that are resistant to activation and have diminished Type 2 effector function. We identified free-fatty acid receptor 3 (Ffar3) as a gene responsible for this effect and demonstrated that FFAR3 signaling reprograms ILC2s to an anti-inflammatory state by promoting their survival, reducing Type 2 cytokine production, and enhancing IL-10 expression. This anti-inflammatory state is dependent on IL-2 signaling, is characterized by decreased ST2 expression, and is distinct from previously described IL-10-producing ILC2 phenotypes. FFAR3-dependent reprogramming is mediated by epidermal growth factor receptor (EGFR) upregulation, and FFAR3's anti-inflammatory effect is partially conserved in human ILC2s.

Animals↗

Simulating the collaborative cross: power of quantitative trait loci detection and mapping resolution in large sets of recombinant inbred strains of mice.

It has been suggested that the collaborative cross, a large set of recombinant inbred strains derived from eight inbred mouse strains, would be a powerful resource for the dissection of complex phenotypes. Here we use simulation to investigate the power of the collaborative cross to detect and map small genetic effects. We show that for a fixed population of 1000 individuals, 500 RI lines bred using a modified version of the collaborative cross design are adequate to map a single additive locus that accounts for 5% of the phenotypic variation to within 0.96 cM. In the presence of strong epistasis more strains can improve detection, but 500 lines still provide sufficient resolution to meet most goals of the collaborative cross. However, even with a very large panel of RILs, mapping resolution may not be sufficient to identify single genes unambiguously. Our results are generally applicable to the design of RILs in other species.

Animals↗

A Multitrait Locus Regulates Sarbecovirus Pathogenesis.

Infectious diseases have shaped the human population genetic structure, and genetic variation influences the susceptibility to many viral diseases. However, a variety of challenges have made the implementation of traditional human Genome-wide Association Studies (GWAS) approaches to study these infectious outcomes challenging. In contrast, mouse models of infectious diseases provide an experimental control and precision, which facilitates analyses and mechanistic studies of the role of genetic variation on infection. Here we use a genetic mapping cross between two distinct Collaborative Cross mouse strains with respect to severe acute respiratory syndrome coronavirus (SARS-CoV) disease outcomes. We find several loci control differential disease outcome for a variety of traits in the context of SARS-CoV infection. Importantly, we identify a locus on mouse chromosome 9 that shows conserved synteny with a human GWAS locus for SARS-CoV-2 severe disease. We follow-up and confirm a role for this locus, and identify two candidate genes, CCR9 and CXCR6, that both play a key role in regulating the severity of SARS-CoV, SARS-CoV-2, and a distantly related bat sarbecovirus disease outcomes. As such we provide a template for using experimental mouse crosses to identify and characterize multitrait loci that regulate pathogenic infectious outcomes across species. IMPORTANCE Host genetic variation is an important determinant that predicts disease outcomes following infection. In the setting of highly pathogenic coronavirus infections genetic determinants underlying host susceptibility and mortality remain unclear. To elucidate the role of host genetic variation on sarbecovirus pathogenesis and disease outcomes, we utilized the Collaborative Cross (CC) mouse genetic reference population as a model to identify susceptibility alleles to SARS-CoV and SARS-CoV-2 infections. Our findings reveal that a multitrait loci found in chromosome 9 is an important regulator of sarbecovirus pathogenesis in mice. Within this locus, we identified and validated CCR9 and CXCR6 as important regulators of host disease outcomes. Specifically, both CCR9 and CXCR6 are protective against severe SARS-CoV, SARS-CoV-2, and SARS-related HKU3 virus disease in mice. This chromosome 9 multitrait locus may be important to help identify genes that regulate coronavirus disease outcomes in humans.

Animals↗

Strategies for mapping and cloning quantitative trait genes in rodents.

Over the past 15 years, more than 2,000 quantitative trait loci (QTLs) have been identified in crosses between inbred strains of mice and rats, but less than 1% have been characterized at a molecular level. However, new resources, such as chromosome substitution strains and the proposed Collaborative Cross, together with new analytical tools, including probabilistic ancestral haplotype reconstruction in outbred mice, Yin-Yang crosses and in silico analysis of sequence variants in many inbred strains, could make QTL cloning tractable. We review the potential of these strategies to identify genes that underlie QTLs in rodents.

Animals↗

Specificity of antigens on UV radiation-induced antigenic tumor cell variants measured in vitro and in vivo.

In vitro exposure of nonimmunogenic murine tumor cells to UV radiation (UVR) generates highly antigenic variants that are immunologically rejected by normal, syngeneic mice. The purpose of this study was to determine whether these antigenic variants cross-react immunologically with the parental tumor and whether the UVR-associated antigen unique to UVR-induced tumors is also present on the variants. Antigenic (regressor) variants and nonimmunogenic (progressor) clones derived from UV-irradiated cultures of the C3H K1735 melanoma and SF19 spontaneous fibrosarcoma cell lines were used to address these questions. In an in vivo immunization and challenge assay, the antigenic variants did not induce cross-protection among themselves, but each induced immunity against the immunizing variant, the parent tumor cells, and nonimmunogenic clones derived from UV-irradiated parent cultures. Therefore, the variants can be used to induce in mice a protective immunity that prevents the growth of the parent tumor and nonimmunogenic clones, but not other antigenic variants. In contrast, immunization with cells of the parental tumor or the nonimmunogenic clones induced no protective immunity against challenge with any of the cell lines. Utilizing the K1735 melanoma-derived cell lines in vitro, T-helper (Th) cells isolated from tumor-immunized mice were tested for cross-reactivity by their ability to collaborate with trinitrophenyl-primed B-cells in the presence of trinitrophenyl-conjugated tumor cells. Also, the cross-reactivity of cytotoxic T-lymphocytes from tumor-immunized mice was assessed by a 4-h 51Cr-release assay. Antigenic variants induced cytotoxic T-lymphocytes and Th activity that was higher than that induced by the parent tumor and nonimmunogenic clones from the UVR-exposed parent tumor and cross-reacted with the parental tumor cells and nonimmunogenic clones, but not with other antigenic variants. Furthermore, upon transplantation, the UVR-induced antigenic variants grew in UV-irradiated and immunosuppressed mice, but not in untreated mice indicating that the variants expressed the determinant recognized by suppressor T-cells present in UV-irradiated mice. These results demonstrate that highly antigenic cells generated by the in vitro exposure of two different murine tumors to UV radiation express a determinant shared with the parental tumor cells and nonimmunogenic clones, a unique variant-specific determinant and the suppressor cell-defined determinant present on UVR-induced tumors. Based on these results, two models are proposed to explain the make-up of the antigenic determinants present on the UVR-induced antigenic variants.

Animals↗

Cross-talk between alpha(4)beta(1)/alpha(5)beta(1) and c-Kit results in opposing effect on growth and survival of hematopoietic cells via the activation of focal adhesion kinase, mitogen-activated protein kinase, and Akt signaling pathways.

Erythroid progenitor cells (EPCs) are deficient in mice lacking either the ligand stem cell factor (SCF), its receptor c-Kit, or beta(1)-integrins. In nonhematopoietic cells, integrins and receptor tyrosine kinases can collaborate to modulate cellular functions, providing evidence for cross-talk between signals emerging from these cell surface molecules. Using specific recombinant fibronectin peptides that contain the binding site for the integrin alpha(4)beta(1) (FN-H296) or alpha(5)beta(1) (FN-CH271) or both alpha(4)beta(1) and alpha(5)beta(1) (FN-CH296), this study investigated the effect of adhesion alone, or in combination with activation of c-Kit, on functional and biochemical outcomes in an EPC line, G1E-ER2, and primary EPCs. G1E-ER2 cells and primary EPCs cultured on FN-CH271 in the presence of c-Kit activation led to a significant increase in proliferation in comparison with cells grown on FN-H296 or FN-CH296. G1E-ER2 cells cultured on FN-H296 or FN-CH296 resulted in significant cell death in comparison to cells grown on FN-CH271. Activation of c-Kit enhanced the survival of G1E-ER2 cells grown on FN-H296 or FN-CH296; however, the rescue was only partial. The reduced survival of G1E-ER2 cells on FN-H296 correlated with reduced activation of Akt and expression of Bcl-2 and Bcl-x(L), whereas increase in proliferation on FN-CH271 correlated with significantly enhanced and sustained activation of focal adhesion kinase (FAK) and extracellular-regulated kinase (ERK) pathways. These data demonstrate that adhesion-induced signals emanating from ligation of alpha(4)beta(1) and alpha(5)beta(1) result in distinct biologic outcomes, including death via alpha(4)beta(1) and survival/proliferation via alpha(5)beta(1). (Blood. 2001;97:1975-1981)

Animals↗

The augmentation of tumor-specific immunity using haptenic muramyl dipeptide (MDP) derivatives. III. Eradication of disseminated murine chronic leukemia cells by utilizing MDP hapten-reactive helper T-cell activity.

A previous paper has demonstrated that enhanced tumor-specific immunity could be induced by priming mice with Bacillus Calmette Guerin (BCG) and subsequently immunizing them with syngeneic tumor cells modified with BCG-cross-reactive muramyl dipeptide (MDP) hapten. The present study establishes a tumor-specific immunotherapy protocol for a murine chronic leukemia based on the above T-T cell collaboration between antitumor effector T cells and anti-MDP hapten helper T cells induced by BCG priming. BALB/c mice which had been primed to BCG were injected intravenously (i.v.) with viable, syngeneic BCL1 leukemia cells. One week later, these mice were immunized intraperitoneally (i.p.) with unmodified or MDP hapten-modified, 10,000 R X-irradiated BCL1 cells, followed by 4 booster immunizations at 5-day intervals. The administration of unmodified BCL1 tumor cells into BCG-primed mice failed to prevent them from tumor death due to the persistent growth of preinjected BCL1 cells. In contrast, the immunization of BCG-primed, BCL1 leukemia-cell-bearing mice with MDP-modified BCL1 cells resulted in a high growth inhibition of leukemia cells and protection of these mice from death by leukemia. It was also revealed that potent tumor-specific, T-cell-mediated immunity was generated in mice which survived in this immunotherapy model. Thus, these results indicate that administration of MDP hapten-modified, syngeneic leukemia cells into leukemia-bearing mice which have been primed with BCG results in potent tumor-specific, T-cell-mediated immunity attributable to preventing the growth of disseminated leukemic cells.

Acetylmuramyl-Alanyl-Isoglutamine↗

The CD2-scl transgene alters the phenotype and frequency of T-lymphomas in N-ras transgenic or p53 deficient mice.

Abnormal expression of SCL (TAL-1/TCL5) occurs in the majority of paediatric cases of acute T-cell lymphoblastic leukemia (T-ALL). Unexpectedly however, transgenic mice carrying scl coupled to the human T-cell specific CD2 enhancer (CD2-scl) did not spontaneously develop T-cell lymphomas despite high levels of scl expression in their thymocytes. Analogous to other transgenic models of lymphomagenesis, it is likely that additional genetic abnormalities are required to cooperate with scl to trigger lymphomagenesis. Two possible candidates are the p53 and N-ras genes which are mutated in some cases of T-ALL, particularly in relapsed disease. Therefore, we examined lymphomagenesis in the progeny of CD2-scl mice crossed with N-ras transgenic mice or p53 deficient. Surprisingly, the frequency of lymphomas in the p53 nullizygous or N-ras transgenic mice was not enhanced by expression of the scl transgene. In fact, expression of scl in both genetic backgrounds paradoxically reduced the frequency of thymic lymphomas and, at least in the p53 nullizygous mice, shifted the pattern of organ involvement to the peripheral lymphoid organs. In contrast, CD2-scl transgene expression accelerated lymphomagenesis in p53 heterozygous mice. These data suggest that the collaborative effects of scl with N-ras or p53 vary according to the developmental stage of the T-cell.

Alleles↗

bmi-1 transgene induces lymphomas and collaborates with myc in tumorigenesis.

The bmi-1 gene was discovered as a frequent target of Moloney virus insertion in virally accelerated B-lymphoid tumors of E mu-myc transgenic mice and hence is thought to collaborate with the myc gene in lymphomagenesis, but its oncogenic potential has not previously been tested directly. To determine whether bmi-1 overexpression can contribute to hematopoietic neoplasia in vivo, strains of transgenic mice were generated in which bmi-1 expression was directed to the lymphoid compartment by a coupled immunoglobulin heavy chain enhancer (E mu). Although the E mu-bmi-1 transgene was expressed in both B and T cells, lymphoid development was not perturbed. Nevertheless, 14% of the mice in the strain with highest expression have developed lymphoma. Unexpectedly, most tumors were of the T-cell lineage, although one case of B lymphoma was observed. Furthermore, cross breeding E mu-bmi-1 and E mu-myc mice established that the bmi-1 transgene markedly accelerated the onset of pre-B and B lymphomas. These results demonstrate directly that bmi-1 can contribute to lymphomagenesis in the T and B cell lineages and collaborate with the myc gene in tumor development.

Animals↗

Elevated frequency of loss of heterozygosity in mammary tumors arising in mouse mammary tumor virus/neu transgenic mice.

Loss of heterozygosity (LOH) analysis was performed on 62 mammary tumors that were induced in (BALB/c x C57BL/6)F1 mouse mammary tumor virus/neu transgenic mice. Eighty-six simple sequence length polymorphism markers were used to cover all of the somatic chromosomes. Frequency of LOH was observed to be significant for chromosomes 4 (50%), 19 (32%), and 8 (21%). On chromosome 4, at least three distinct regions of allelic deletions could be identified: one proximal to 22 cM; the second close to the p16INK4a/p15INK4b locus, which is commonly deleted in various tumors; and the third one in the proximity of Mom1. The frequency of LOH on chromosome 19 was the same for the four markers used. Our data suggested the presence of two distinct LOH loci, one proximal to 47 cM and the other at the distal region. On chromosome 8, possibly two distinct LOH loci could be recognized, one around 52 cM and the other one at 67 cM or distal to it. These regions map close to E-cadherin (Cdh1) and M-cadherin (Cdh15) loci, respectively. Because LOH sites are thought to harbor tumor suppressor genes, this allelotype screening has allowed the mapping of putative tumor suppressor genes that may be implicated, in collaboration with the erbB-2/neu oncogene, in the development of mammary tumors in these transgenic mice.

Acyltransferases↗

Skin-specific caspase-1-transgenic mice show cutaneous apoptosis and pre-endotoxin shock condition with a high serum level of IL-18.

To study the pathophysiological roles of overexpressed caspase-1 (CASP1), originally designated as IL-1 beta-converting enzyme, we generated transgenic mice in which human CASP1 is overexpressed in their keratinocytes. The transgenic mice spontaneously developed recalcitrant dermatitis and skin ulcers, characterized by the presence of massive keratinocyte apoptosis. The skin of the mice contained the active form of human CASP1 and expressed mRNA for caspase-activated DNase, an effector endonuclease responsible for DNA fragmentation. Their skin and sera showed elevated levels of mature IL-18 and IL-1 beta, but not of IFN-gamma. The plasma from these animals induced IFN-gamma production by IL-18-responsive NK cells. Administration of heat-killed Propionibacterium acnes, a potent in vivo type 1 cell inducer, caused IFN-gamma-mediated lethal liver injury in the transgenic mice, which was completely inhibited by treatment with neutralizing anti-IL-18 Ab. These results indicated that in vivo overexpression of CASP1 caused spontaneous apoptotic tissue injury and rendered mice highly susceptible to exogenous type 1 cell-inducing condition in collaboration with endogenously accumulated proinflammatory cytokines.

Animals↗

Targeting of T-B interaction using heteroconjugate antibody.

We have deliberately targeted collaboration between T cells and certain B cells by using a heteroconjugate (HETCONJ) antibody. This specific reagent was created by cross-linking the F(ab')2 portions of anti-I-Ab and anti-CD3 monoclonal antibodies. Spleen cells from B6 (I-Ab) but not bm12 (I-Abm12) mice proliferated in vitro in the presence of the HETCONJ. Similarly, T-cell dependent IgM secretion was induced in B cells from B6, yet only weakly in B cells from bm 12 mice. Using B cells from Igh allotype double congenic (B6.C20 Igha/I-Ab and bm12, Ighb/I-Abm12) mice in co-culture experiments, we have used the HETCONJ to study linked versus bystander T-B interaction. B-cell activation, mediated by HETCONJ, was 10 times greater in unseparated than in resting splenic B cells. T-B interaction through T-B contact was more efficient than activation through bystander effects both for unseparated and resting splenic B cells. Large, already activated B cells, in contrast, did not show a preference for linked recognition. Our reagent has mimicked some of the events involved in T-B collaboration and may be useful in studying the molecular basis of cellular interactions.

Animals↗

p53 deficiency accelerates induction and progression of esophageal and forestomach tumors in zinc-deficient mice.

The p53 tumor suppressor protein plays a pivotal role in preventing uncontrolled cellular proliferation. By contrast, zinc deprivation enhances esophageal cell proliferation and the induction of esophageal tumors in rodents by N-nitrosomethylbenzylamine (NMBA). We investigated whether p53 deficiency rendered zinc-deficient (ZD) mice more susceptible to NMBA-induced esophageal/forestomach carcinogenesis. At 6-7 weeks of age, p53 null (-/-), heterozygous (+/-), and wild-type (+/+) mice were placed on ZD or zinc-sufficient (ZS) diets to form six experimental groups: ZD:p53-/-; ZD:p53+/-; ZD:p53+/+; ZS:p53-/-; ZS:p53+/-; and ZS:p53+/+. After 3 weeks, 15-23 mice in each group were treated once with NMBA (2 mg/kg body weight). Control animals were untreated. Zinc deficiency alone induced unrestrained cellular proliferation in the esophagus and forestomach of p53-/- mice. Forestomach tumors were first detected in a ZD:p53-/- mouse at 13 days. By 30 days, 100% (21 of 21) of ZD:p53-/- mice developed forestomach tumors and 38% showed esophageal tumors versus 42 and 0% in ZS:p53-/- mice (P < 0.004, esophagus; P < 0.001, forestomach). ZD:p53-/- mice showed an accelerated progression to malignancy, with 10% of esophageal tumors and 38% of forestomach tumors presenting as carcinomas. Nearly 20% of ZD:p53-/- mice developed esophageal Barrett's metaplasia, a lesion not previously seen in NMBA-induced neoplasia. ZD:p53+/- mice had significantly higher tumor incidence than ZS:p53+/- mice. The order of tumor incidence in forestomach was as follows: naught incidence in ZS:p53+/+ mice; ZD:p53-/- > ZD:p53+/- > ZS:p53-/- > ZD:p53+/+ >/= ZS:p53+/- > ZS:p53+/+. The rapid rate of tumor induction/progression in ZD:p53-/- mice was accompanied by an increase in the rate of cell proliferation and a decrease in apoptosis. cDNA array expression analysis of known genes identified a 5-fold up-regulation of cytokeratin 14 mRNA expression in ZD:p53-/- versus ZS:p53-/- forestomach, a result showing gene-modulating effects of zinc deficiency. Cytokeratin 14 is a biomarker in human esophageal carcinogenesis. Our findings provide in vivo evidence for the collaboration of a deficiency of both p53 and zinc in esophageal carcinogenesis and reveal molecular targets of this collaboration.

Animals↗

Cancer dormancy. VII. A regulatory role for CD8+ T cells and IFN-gamma in establishing and maintaining the tumor-dormant state.

Dormant tumor cells resistant to ablative cancer therapy represent a significant clinical obstacle due to later relapse. Experimentally, the murine B cell lymphoma (BCL1) is used as a model of tumor dormancy in mice vaccinated with the BCL1 Ig. Here, we used this model to explore the cellular mechanisms underlying dormancy. Our previous studies have demonstrated that T cell-mediated immunity is an important component in the regulation of tumor dormancy because Id-immune T cells adoptively transferred into passively immunized SCID mice challenged with BCL1 cells significantly increased the incidence and duration of the dormant state. We have extended these observations and demonstrate that CD8+, but not CD4+, T cells are required for the maintenance of dormancy in BCL1 Ig-immunized BALB/c mice. In parallel studies, the transfer of Id-immune CD8+ cells, but not Id-immune CD4+ cells, conferred significant protection to SCID mice passively immunized with nonprotective levels of polyclonal anti-Id and then challenged with BCL1 cells. Furthermore, the ability of CD8+ T cells to induce a state of dormancy in passively immunized SCID mice was completely abrogated by treatment with neutralizing alpha-IFN-gamma mAbs in vivo. In vitro studies demonstrated that IFN-gamma alone or in combination with reagents to cross-link the surface Ig induced both cell cycle arrest and apoptosis in a BCL1 cell line. Collectively, these data demonstrate a role for CD8+ T cells via endogenous production of IFN-gamma in collaboration with humoral immunity to both induce and maintain a state of tumor dormancy.

Animals↗

Studies on IgE production in mice. I. Spontaneous suppression of IgE production in SJA/9 mice.

IgE levels after Nippostrongylus brasiliensis infestation were high in all strains of mice examined except in the SJA/9 strain. However, surface IgE levels on B cells were not different from those observed in the SJL strain. Most surface IgE-bearing cells also had surface IgM molecules. We suggest that the surface IgE-bearing cells are precursors of IgE-producing cells. In adoptive transfer, hapten-specific IgE antibody was produced when hapten-primed cells from SJA/9 mice were transferred together with cells from SJL donors infested with N. brasiliensis but not when the cells were from SJA/9 donors. It is suggested that the lack of collaboration between hapten-primed B cells and cells from infested mice is a genetic trait of the SJA/9 strain.

Animals↗