IKK kinase is essential for the B cell maturation and secondary lymphoid organ development. In the current study, we evaluated the role of IKK in the marginal zone and follicular B lymphocyte development by genetically deleting IKK from the B cell lineage using CD19-Cre mice. The loss of IKK did not affect the normal development of early B cell progenitors. However, a significant decline was observed in the percentage of immature B lymphocytes, mature marginal zone and follicular B cells along with a severe disruption of splenic marginal and follicular B cell zones. A gene expression analysis performed on the RNA extracted from the newly formed B cells (B220+IgMhi) revealed that IKK deficiency produces significant changes in the expression of genes involved in MZ and FO B lymphocyte survival, homing and migration. And several among those genes identified belong to G protein family. Specifically, we validated the upregulated expression of regulator of G protein signaling 13 (RGS13), which is a GTPase activating protein (GAP) that negatively regulates G protein signaling and impede B cell migration. Likewise, promigratory B lymphocyte receptor, the sphingosine-1-phosphate receptor 3 (SIPR3) that couple to Gi showed significantly reduced expression. In addition, an in silico analysis of gene product interactions revealed NF-B signaling pathways to be a major gene regulating networks perturbed with IKK deletion. Taken together, this study reveals IKKNF-B and G protein signaling axis to be central for the MZ and FO B cells survival, maintenance, homing and migration.
IKKα deficiency disrupts the development of marginal zone and follicular B cells.
Specimen part
View SamplesSTAT5 is critical for differentiation, proliferation and survival of progenitor B cells suggesting a possible role in Acute Lymphoblastic Leukemia (ALL). Herein, we show increased expression of activated STAT5 in ALL patients, which correlates with treatment outcome. Mutations in Ebf1 and Pax5, genes critical for B cell development have also been identified in human ALL. To determine whether mutations in Ebf1 or Pax5 synergize with STAT5 activation to induce ALL we crossed mice expressing a constitutively active form of STAT5 (Stat5b-CA) with mice heterozygous for Ebf1 or Pax5. Haploinsufficiency of either Pax5 or Ebf1 synergized with Stat5b-CA to rapidly induce ALL in 100% of the mice. The leukemic cells displayed reduced expression of both Pax5 and Ebf1 but this had little affect on most EBF1 or PAX5 target genes. However, a subset of these genes was deregulated and included a large percentage of potential tumor suppressor genes and oncogenes. Further, most of these genes appear to be jointly regulated by both EBF1 and PAX5. Our findings suggest a model whereby small perturbations in a self-reinforcing network of transcription factors critical for B cell development, specifically PAX5 and EBF1, cooperate with STAT5 activation to initiate ALL.
Ebf1 or Pax5 haploinsufficiency synergizes with STAT5 activation to initiate acute lymphoblastic leukemia.
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View SamplesThe generation of sufficient numbers of mature ventricular myocytes for effective cell-based therapy is a central barrier for cardiac regenerative medicine. Here we demonstrate that induced pluripotent stem cells (iPSCs) can be derived from murine ventricular myocytes, and consistent with other reports of iPSCs derived from various somatic cell types, ventricular myocyte derived iPSCs (ViPSCs) exhibit a markedly higher propensity to differentiate into beating cardiomyocytes as compared to genetically-matched embryonic stem cells (ESCs) or iPSCs derived from tail-tip fibroblasts. Strikingly, ViPSC-derived cardiomyocytes form up to 99% ventricular myocytes suggesting that ventricular myocyte-derived iPSCs may be a viable strategy to generate specific cardiomyocyte subtypes for cell-based therapies. The enhanced ventricular myogenesis in ViPSCs is mediated via increased numbers of cardiovascular progenitors at early stages of differentiation. In order to investigate the mechanism of enhanced ventricular myogenesis from ViPSCs, we performed global gene expression and DNA methylation analysis, which revealed a distinct epigenetic signature that may be involved in specifying the ventricular myocyte fate in pluripotent stem cells.
Highly efficient derivation of ventricular cardiomyocytes from induced pluripotent stem cells with a distinct epigenetic signature.
Specimen part
View SamplesWe generated Ikk-KA/KA knock-in mice (KA/KA), in which an ATP binding site of Ikk Lys 44 was replaced by alanine. The knock-in mice develop severe skin lesions and begin to die after 6 to 10 months. We also found lung SCCs in some of the mice. To study lung SCC development, we stabilize the skin condition by crossing KA/KA with Lori.Ikk transgenic mice to generate KA/KA-Lori.Ikk mice, which 100% spontaneously developed lethal lung SCC at 4 to 6 months of age.
The pivotal role of IKKα in the development of spontaneous lung squamous cell carcinomas.
Age, Specimen part
View SamplesThe transcription factor STAT5 plays a critical role in B cell acute lymphoblastic leukemia (B-ALL). How STAT5 mediates this effect is unclear. Here we demonstrate that STAT5 activation cooperates with defects in the pre-BCR signaling components encoded by Blnk, Btk, Prkcb, Nfkb1, and Ikzf1 to initiate B-ALL. STAT5 antagonizes NF-B and IKAROS by opposing regulation of shared target genes. STAT5 binding was enriched at super-enhancers, which were associated with an opposing network of transcription factors, including PAX5, EBF1, PU.1, IRF4, and IKAROS. Patients with high ratios of active STAT5 to NF-B or IKAROS have more aggressive disease. Our studies illustrate that an imbalance of two opposing transcriptional programs drive B-ALL, and suggest that restoring the balance of these pathways may inhibit B-ALL.
Antagonism of B cell enhancer networks by STAT5 drives leukemia and poor patient survival.
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View SamplesSphingosine 1-phosphate (S1P) is a bioactive lipid whose levels are tightly regulated by its synthesis and degradation. Intracellularly, S1P is dephosphoryled by the actions of two S1P-specific phosphatases, sphingosine 1-phosphate phosphatase 1 and 2. To identify the physiologic functions of S1P phosphatase 1, we have studied mice with its gene, Sgpp1, deleted. Sgpp1-/- mice appeared normal at birth but during the first week of life, they exhibited stunted growth, suffered desquamation, and most died before weaning. Interestingly, the epidermal permeability barrier developed normally during embryogenesis. Sgpp1 -/- pups and surviving adults exhibited epidermal hyperplasia and abnormal expression of keratinocyte differentiation markers. Keratinocytes isolated from Sgpp1 -/- skin had increased intracellular S1P levels, and expressed a gene expression profile that indicated enhanced differentiation. The results reveal S1P metabolism as a regulator of keratinocyte differentiation and epidermal homeostasis.
Sphingosine-1-phosphate phosphatase 1 regulates keratinocyte differentiation and epidermal homeostasis.
Specimen part
View SamplesDeletion of the gene encoding Foxa2, a winged helix transcription factor selectively expressed in respiratory epithelial cells, caused spontaneous pulmonary eosinophilic inflammation and goblet cell metaplasia. Loss of Foxa2 induced the recruitment and activation of myeloid dendritic cells (mDCs) and Th2 cells in the lung, and was associated with the increased production of T helper 2 (Th2) cytokines and chemokines. mRNA microarray analysis demonstrated that deletion of Foxa2 induced the expression of a number of mRNAs regulating pulmonary dendritic cell activation, Th2 mediated inflammation, and goblet cell differentiation. The spontaneous pulmonary inflammation and goblet cell metaplasia caused by loss of Foxa2 was inhibited by treatment of newborn Foxa2/ mice with monoclonal IL-4Ralpha antibody. Expression of Foxa2 in non-ciliated secretory cells (Clara cells) in vivo inhibited goblet cell differentiation induced by pulmonary allergen exposure. The respiratory epithelium plays a central role in the regulation of Th2-mediated inflammation and innate immunity in the developing lung in a process regulated by Foxa2.
Foxa2 programs Th2 cell-mediated innate immunity in the developing lung.
Specimen part
View SamplesFoxp3+ regulatory T (Treg) cells prevent inflammatory disease but the mechanistic basis of suppression is not understood completely . Gene silencing by RNA interference can act in a cell-autonomous and non-cell-autonomous manner, providing mechanisms of inter-cellular regulation. Here, we demonstrate that non-cell-autonomous gene silencing, mediated by miRNA-containing exosomes, is a mechanism employed by Treg cells to suppress T cell-mediated disease. Treg cells transferred microRNAs (miRNA) to various immune cells, including T helper 1 (Th1) cells, suppressing Th1 cell proliferation and cytokine secretion. Use of Dicer-deficient or Rab27a and Rab27b double-deficient Treg cells to disrupt miRNA-biogenesis or the exosomal pathway, respectively, established a requirement for miRNAs and exosomes for Treg cell-mediated suppression. Transcriptional analysis and miRNA inhibitor studies showed that exosome-mediated transfer of Let-7d from Treg cell to Th1 cells contributed to suppression and prevention of systemic disease. These studies reveal a mechanism of Treg cell-mediated suppression mediated by miRNA-containing exosomes.
MicroRNA-containing T-regulatory-cell-derived exosomes suppress pathogenic T helper 1 cells.
Specimen part
View SamplesFumarylacetoacetate hydrolase (Fah), the last enzyme of the tyrosine degradation pathway, is specifically expressed in hepatocytes in the liver. Loss of Fah leads to liver failure in mice within 6-8 weeks. This can be prevented by blocking tyrosine degradation upstream of Fah with 2-(2-nitro-4-trifluoromethylbenzoyl)-1,3-cyclohexanedione (NTBC). Here, we investigate the impact of p21 on global gene expression in Fah deficiency.
Loss of p21 permits carcinogenesis from chronically damaged liver and kidney epithelial cells despite unchecked apoptosis.
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View SamplesTranscriptional control is dependent on a vast network of epigenetic modifications. One epigenetic mark of particular interest is tri-methylation of lysine 27 on histone H3 (H3K27me3), which is catalyzed and maintained by the Polycomb Repressor Complex (PRC2). Although this histone mark is studied widely, the precise relationship between its local pattern of enrichment and regulation of gene expression is currently unclear. We have used ChIP-seq to generate genome wide maps of H3K27me3 enrichment, and have identified three enrichment profiles with distinct regulatory consequences. First, a broad domain of H3K27me3 enrichment across the body of genes corresponds to the canonical view of H3K27me3 as inhibitory to transcription. Second, a peak of enrichment around the transcription start site is commonly associated with bivalent genes, where H3K4me3 also marks the TSS. Finally and most surprisingly, we identified an enrichment profile with a peak in the promoter of genes that is associated with active transcription. Genes with each of these three profiles were found in different proportions in each of the cell types studied. The data analysis techniques developed here will be useful for the identification of common enrichment profiles for other histone modifications that have important consequences for transcriptional regulation.
ChIP-seq analysis reveals distinct H3K27me3 profiles that correlate with transcriptional activity.
Specimen part
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