NOTCH1 pathway activation contributes to the pathogenesis of over 60% of T-cell acute lymphoblastic leukemia (T-ALL). While Notch is thought to exert the majority of its effects through ...transcriptional activation of Myc, it also likely has independent roles in T-ALL malignancy. Here, we utilized a zebrafish transgenic model of T-ALL, where Notch does not induce Myc transcription, to identify a novel Notch gene expression signature that is also found in human T-ALL and is regulated independently of Myc. Cross-species microarray comparisons between zebrafish and mammalian disease identified a common T-ALL gene signature, suggesting that conserved genetic pathways underlie T-ALL development. Functionally, Notch expression induced a significant expansion of pre-leukemic clones; however, a majority of these clones were not fully transformed and could not induce leukemia when transplanted into recipient animals. Limiting-dilution cell transplantation revealed that Notch signaling does not increase the overall frequency of leukemia-propagating cells (LPCs), either alone or in collaboration with Myc. Taken together, these data indicate that a primary role of Notch signaling in T-ALL is to expand a population of pre-malignant thymocytes, of which a subset acquire the necessary mutations to become fully transformed LPCs.
T-cell acute lymphoblastic leukemia (T-ALL) is a challenging clinical entity with high rates of induction failure and relapse. To discover the genetic changes occurring in T-ALL, and those ...contributing to relapse, we studied zebrafish (Danio rerio) T-ALL samples using array comparative genomic hybridization (aCGH). We performed aCGH on 17 T-ALLs from four zebrafish T-ALL models, and evaluated similarities between fish and humans by comparing all D. rerio genes with copy number aberrations (CNAs) with a cohort of 75 published human T-ALLs analyzed by aCGH. Within all D. rerio CNAs, we identified 893 genes with human homologues and found significant overlap (67%) with the human CNA dataset. In addition, when we restricted our analysis to primary T-ALLs (14 zebrafish and 61 human samples), 10 genes were recurrently altered in > 3 zebrafish cancers and ≥ 4 human cases, suggesting a conserved role for these loci in T-ALL transformation across species. We also conducted iterative allo-transplantation with three zebrafish malignancies. This technique selects for aggressive disease, resulting in shorter survival times in successive transplant rounds and modeling refractory and relapsed human T-ALL. Fifty-five percent of original CNAs were preserved after serial transplantation, demonstrating clonality between each primary and passaged leukemia. Cancers acquired an average of 34 new CNAs during passaging. Genes in these loci may underlie the enhanced malignant behavior of these neoplasias. We also compared genes from CNAs of passaged zebrafish malignancies with aCGH results from 50 human T-ALL patients who failed induction, relapsed or would eventually relapse. Again, many genes (88/164) were shared by both datasets. Further, nine recurrently altered genes in passaged D. rerio T-ALL were also found in multiple human T-ALL cases. These results suggest that zebrafish and human T-ALLs are similar at the genomic level, and are governed by factors that have persisted throughout evolution.
T-cell neoplasias are common in pediatric oncology, and include acute lymphoblastic leukemia (T-ALL) and lymphoblastic lymphoma (T-LBL). These cancers have worse prognoses than their B-cell ...counterparts, and their treatments carry significant morbidity. Although many pediatric malignancies have characteristic translocations, most T-lymphocyte-derived diseases lack cytogenetic hallmarks. Lacking these informative lesions, insight into their molecular pathogenesis is less complete. Although dysregulation of the NOTCH1 pathway occurs in a substantial fraction of cases, many other genetic lesions of T-cell malignancy have not yet been determined. To address this deficiency, we pioneered a phenotype-driven forward-genetic screen in zebrafish (Danio rerio). Using transgenic fish with T-lymphocyte-specific expression of enhanced green fluorescent protein (EGFP), we performed chemical mutagenesis, screened animals for GFP(+) tumors, and identified multiple lines with a heritable predisposition to T-cell malignancy. In each line, the patterns of infiltration and morphological appearance resembled human T-ALL and T-LBL. T-cell receptor analyses confirmed their clonality. Malignancies were transplantable and contained leukemia-initiating cells, like their human correlates. In summary, we have identified multiple zebrafish mutants that recapitulate human T-cell neoplasia and show heritable transmission. These vertebrate models provide new genetic platforms for the study of these important human cancers.
Pertussis toxin (PTX) is a potent ancillary adjuvant used to elicit several different autoimmune diseases, including experimental allergic encephalomyelitis (EAE). To delineate the genetics of PTX ...effect in EAE, we mapped EAE-modifying (eae-m) loci in cohorts of backcross mice immunized with and without PTX. In this study, we analyzed the genetic basis of EAE susceptibility and severity and the intermediate phenotypes of mononuclear cell infiltration, suppuration, and demyelination. In animals immunized with PTX, one major locus, eae9, controls disease susceptibility and severity. Eae9 also regulates the extent of mononuclear cell infiltration of the spinal cord in male mice. Without PTX, five eae-m loci were noted, including three new loci in intervals on chromosomes 8 (eae14), 10 (eae17), and 18 (eae18). Taken together, these results suggest that eae9 controls the effects of PTX in EAE susceptibility, and is capable of overriding the other genetic checkpoints in the pathogenesis of this disease.
Bphs controls
Bordetella pertussis
toxin (PTX)–induced vasoactive amine sensitization elicited by histamine (VAASH) and has an established role in autoimmunity. We report that congenic mapping links
...Bphs
to the histamine H
1
receptor gene (
Hrh1
/H1R) and that H1R differs at three amino acid residues in VAASH-susceptible and -resistant mice.
Hrh1
-/-
mice are protected from VAASH, which can be restored by genetic complementation with a susceptible
Bphs/Hrh1
allele, and experimental allergic encephalomyelitis and autoimmune orchitis due to immune deviation. Thus, natural alleles of
Hrh1
control both the autoimmune T cell and vascular responses regulated by histamine after PTX sensitization.
BACKGROUND: The ubiquitous use of phthalate esters in plastics, personal care products and food packaging materials results in widespread general population exposure. In this report, we extend our ...preliminary study on the relationship between urinary concentrations of phthalate metabolites and sperm DNA damage among a larger sample of men and include measurements of mono-(2-ethyl-5-hydroxyhexyl) phthalate (MEHHP) and mono-(2-ethyl-5-oxohexyl) phthalate (MEOHP), two oxidative metabolites of di-(2-ethylhexyl) phthalate (DEHP). METHODS: Among 379 men from an infertility clinic, urinary concentrations of phthalate metabolites were measured using isotope-dilution high-performance liquid chromatography–tandem mass spectrometry. Sperm DNA damage measurements, assessed with the neutral comet assay, included comet extent (CE), percentage of DNA in tail (Tail%) and tail distributed moment (TDM). RESULTS: Monoethyl phthalate (MEP), a metabolite of diethyl phthalate, was associated with increased DNA damage, confirming our previous findings. Mono-(2-ethylhexyl) phthalate (MEHP), a metabolite of DEHP, was associated with DNA damage after adjustment for the oxidative DEHP metabolites. After adjustment for MEHHP, for an interquartile range increase in urinary MEHP, CE increased 17.3% 95% confidence interval (CI) = 8.7–25.7%, TDM increased 14.3% (95% CI = 6.8–21.7%) and Tail% increased 17.5% (95% CI = 3.5–31.5%). CONCLUSIONS: Sperm DNA damage was associated with MEP and with MEHP after adjusting for DEHP oxidative metabolites, which may serve as phenotypic markers of DEHP metabolism to ‘less toxic’ metabolites. The urinary levels of phthalate metabolites among these men were similar to those reported for the US general population, suggesting that exposure to some phthalates may affect the population distribution of sperm DNA damage.
Pertussis toxin (PTX) is the primary component responsible for eliciting the majority of biological activities associated with Bordetella pertussis, including the induction of several tissue-adjuvant ...models of organ-specific autoimmune disease. PTX, when administered in vivo, enhances vascular permeability, which is made manifest by a concomitant increase in sensitivity to a variety of agents and treatments affecting the vascular bed. One such agent is histamine, and the response to PTX, as measured by hypersensitivity following vasoactive amine challenge, is genetically controlled by the Bphs locus. Susceptibility to the induction of both experimental allergic encephalomyelitis (EAE) and experimental allergic orchitis (EAO) in mice is associated with, and in the latter case linked to, a susceptible allele at this locus. We report here the mapping of the Bphs locus to mouse chromosome 6, telomeric of Tcrb and centromeric of Prp (D6Nds8). This region also contains a number of loci of immunologic relevance including Igk, Ly-2, Ly-3, Il-5r, Ly-35, Ly-4, and Tnfr-2.
Anthrax lethal toxin (LT) is the principal virulence factor associated with lethal pathologies following infection with
Bacillus anthracis
. Macrophages are the primary effector cells mediating ...lethality since macrophage-depleted mice are resistant to LT challenge. Recently,
Ltxs1
, the gene controlling differential susceptibility of murine macrophages to cytolysis following
in vitro
exposure to LT, was identified as
Kif1c
. To directly assess the
in vivo
role of
Kif1c
alleles in mortality, we studied a panel of interval-specific recombinant congenic lines carrying various segments of central chromosome 11 derived from LT-resistant DBA/2 mice on the LT-susceptible BALB/c background. The results of this study reveal that mortality is controlled by three linked quantitative trait loci (QTL):
Ltxs1/Kif1c
(42–43 cM),
Ltxs2
(35–37 cM), and
Ltxs3
(45–47 cM). The
Ltxs3
interval encompasses
Nos2
, which is an attractive candidate gene for
Ltxs3
. In this regard, we demonstrate that selective, pharmacologically based inhibition of Nos2 activity
in vivo
partially overrides genetic resistance to LT and that
Nos2
expression as determined by reverse transcription-polymerase chain reaction differs significantly between DBA/2 and BALB/c macrophages. Additionally, to recapitulate dominant resistance to mortality as seen in (BALB/c × DBA/2) F
1 hybrids, DBA/2 alleles are required at all three QTL.
The existence of immunoregulatory genes conferring dominant resistance to autoimmunity is well documented. In an effort to better understand the nature and mechanisms of action of these genes, we ...utilized the murine model of autoimmune orchitis as a prototype. When the orchitis-resistant strain DBA/2J is crossed with the orchitis-susceptible strain BALB/cByJ, the F1hybrid is completely resistant to the disease. By using reciprocal radiation bone marrow chimeras, the functional component mediating this resistance was mapped to the bone marrow-derived compartment. Resistance is not a function of either low-dose irradiation- or cyclophosphamide (20 mg/kg)-sensitive immunoregulatory cells, but can be adoptively transferred by primed splenocytes. Genome exclusion mapping identified three loci controlling the resistant phenotype. Orch3 maps to chromosome 11, whereas Orch4 and Orch5 map to the telomeric and centromeric regions of chromosome 1, respectively. All three genes are linked to a number of immunologically relevant candidate loci. Most significant, however, is the linkage of Orch3 to Idd4 and Orch5 to Idd5, two susceptibility genes which play a role in autoimmune insulin-dependent type 1 diabetes mellitus in the nonobese diabetic mouse.
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