Project description:Early B cell factor 1 (EBF1) is one of the key transcription factors required for orchestrating B-cell lineage development. Although studies have shown that Ebf1 haploinsufficiency is involved in the development of leukemia, no study has been conducted that characterizes the global effect of Ebf1 heterozygosity on the proteome of pro-B lymphocytes. Here, we employ both DIA (Data Independent Acquisition) and shotgun DDA (Data Dependent Acquisition) workflows for profiling proteins that are differently expressed between Ebf1+/+ and Ebf1+/- cells. Both DDA and DIA were able to reveal the downregulation of the EBF1 transcription factor in Ebf1+/- pro-B lymphocytes. Further examination of differentially expressed proteins by DIA revealed that, similar to EBF1, the expression of other B-cell lineage regulators, such as TCF3 and Pax5, is also down-regulated in Ebf1 heterozygous cells. Functional DIA analysis of differentially expressed proteins showed that EBF1 heterozygosity resulted in the deregulation of at least 8 transcription factors involved in lymphopoiesis, and to the deregulation of key proteins playing crucial roles in survival, development and differentiation of pro-B lymphocytes.
Project description:STAT5 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. Gene expression profiling was performed on cells isolated from lymph nodes of Stat5b-CA x Ebf1+/- and Stat5b-CA x Rag2-/- leukemic mice and pre B cells sorted from bone marrow of C57BL/6 mice and Stat5b-CA transgenic mice. 17 Samples.
Project description:We used microarrays to establish whether EBF1 and Pax5 repress similar or unique genes. We found that EBF1 uniquely represses the expression of the T-lineage transcription factor Gata3. Ebf1-/- pre-pro-B cells were transduced with either control MigR1, MigY-EBF1 or MigR-Pax5 viruses. 24 hours later, RNA was isolated and processed for Affymetrix microarray analysis. Cells expressing EBF1, Pax5, or neither were sorted and processed. Scale represents log2 value of normalized signal level.
Project description:STAT5 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.
Project description:In order to investigate how transcription factor dose impacts B-lymphocyte development, we generated mice carrying transheterozygous mutations in the Pax5 and Ebf1 genes. While combined reduction of Pax5 and Ebf1 dose had minimal impact on the development of the earliest CD19+ progenitors, these cells displayed an increased T-cell potential in vivo and in vitro. Alteration in lineage fate depended on a Notch1 mediated conversion process while no signs of de-differentiation could be detected. The differences in functional response to Notch signaling in Wt and Pax5+/-Ebf1+/- pro-B cells was reflected in the transcriptional response because even though cells of both genotypes responded by the generation of intracellular Notch1 and activation of a set of target genes, only the Pax5+/-Ebf1+/- pro-B cells down-regulated genes central for the preservation of stable B-cell identity. This report stresses the importance of transcription factor dose in lymphocyte development and suggests that Pax5 and Ebf1 collaborate to modulate the transcriptional response to Notch signaling after the generation of activated intracellular Notch1. This provides an insight to how transcription factors like Ebf1 and Pax5 preserve cellular identity during differentiation. EBF-1 ChIP-seq: Cultivated CD43+IgM- cells (ProB) cells from Wt, EBF-1 +/-, PAX-5 +/- and EBF-1 +/- PAX-5 +/- (TH) were assessed for EBF-1 binding by ChIP-seq. Replicate Ebf1 ChIP-seq runs on each genotype (Wt, TH, Ebf1+/- and Pax5+/-) and corresponding inputs were pooled into one dataset and analyzed as one combined sample per genotype. RNA-seq no treatment: Briefly, ProB-cells from C57BL/6J Ebf1+/-Pax5+/- (n=4), WT (n=4), Ebf1+/- (n=2) and Pax5+/- (n=2) were sorted and RNA extracted with Qiagen RNeasy Micro Kit. RNA was sent to UCLA Microarray Core for library preparation and were subsequently for 50 cycles of HiSeq 2000 SBS sequencing generating 20-30 million reads/sample. Data analysis was performed with Arraystar® (DNASTAR)). RNA-seq 1 day on OP9DL1 and OP9: In short, in vitro expanded ProB-cells from C57BL/6J Ebf1+/-Pax5+/- (n=4) and WT (n=4) were exposed either on OP9 or OP9-DL1 stromal cells for 24 hours and RNA extracted with Qiagen RNeasy Micro Kit. Due to low reads, two Wt and Ebf1+/-Pax5+/- were sequenced twice. Libraries were constructed using Nugen's Ovation Ultralow Library systems and were subsequently for 50 cycles of NextSeq500 sequencing generating 20-30 million reads/sample. Data analysis was performed with Arraystar® (DNASTAR)).
Project description:Here, we report that EBF1 and Pax5 collaborate in a dose-dependent manner to regulate the IL-7-STAT5 signaling pathway and one-carbon metabolism, whereby we found both diminished and enhanced binding of EBF1 and Pax5 to target genes in compound heterozygous mutant mice. Moreover, single-cell RNA sequencing analysis identified a small subset of wild-type pro-B cells on the trajectory to pre-B cells that share gene expression signatures with leukemic Ebf1+/−Pax5+/− pro-B cells. Thus, a normal expression level of EBF1 and Pax5 is required for safeguarding a potentially vulnerable pro-Bcell subset from a transformation to B-ALL.
Project description:The transcription factors EBF1 and PAX5 are frequently mutated in B cell acute lymphoblastic leukemia (B-ALL). We demonstrate that Pax5+/- x Ebf1+/- compound heterozygous mice develop leukemia with high penetrance. Similar results were seen in Pax5+/- x Ikzf1+/- and Ebf1+/- x Ikzf1+/- mice for B-ALL, or in Tcf7+/- x Ikzf1+/- mice for T cell leukemia. To identify genetic defects that cooperate with Pax5 and Ebf1 compound heterozygosity to initiate leukemia, we carried out a Sleeping Beauty transposon screen. This screen identified a number of cooperating partners including gain-of-function mutations in Stat5 (~65%) and Jak1 (~68%), as well as loss-of-function mutations in Cblb (61%) and Myb (32%). These findings highlight the key role of JAK/STAT5 signaling in cooperating with Pax5 and Ebf1 compound haploinsufficiency to drive B cell transformation. Moreover, these studies pointed to unexpected roles for loss of function mutations in Cblb and Myb in B cell transformation. Subsequent RNA-Seq studies on WT, Pax5+/-, Ebf1+/-, Pax5+/- x Ebf1+/- pre-leukemic, Pax5+/- x Ebf1+/- leukemic cells and Pax5+/- x Ebf1+/- Sleeping Beauty leukemic cells demonstrated upregulation of a PDK1>SGK3>MYC pathway; treatment of Pax5+/- x Ebf1+/- leukemias with PDK1 specific inhibitors blocked their proliferation in vitro. Finally, we identified conserved transcriptional variation in a subset of genes between human leukemias and our mouse B-ALL models. Thus, compound haploinsufficiency for B cell transcription factors likely plays a critical role in transformation of human B cells and suggest that newly developed PDK1 inhibitors may be effective for treating patients characterized by such defects.
Project description:The transcription factors EBF1 and PAX5 are frequently mutated in B cell acute lymphoblastic leukemia (B-ALL). We demonstrate that Pax5+/- x Ebf1+/- compound heterozygous mice develop leukemia with high penetrance. Similar results were seen in Pax5+/- x Ikzf1+/- and Ebf1+/- x Ikzf1+/- mice for B-ALL, or in Tcf7+/- x Ikzf1+/- mice for T cell leukemia. To identify genetic defects that cooperate with Pax5 and Ebf1 compound heterozygosity to initiate leukemia, we carried out a Sleeping Beauty transposon screen. This screen identified a number of cooperating partners including gain-of-function mutations in Stat5 (~65%) and Jak1 (~68%), as well as loss-of-function mutations in Cblb (61%) and Myb (32%). These findings highlight the key role of JAK/STAT5 signaling in cooperating with Pax5 and Ebf1 compound haploinsufficiency to drive B cell transformation. Moreover, these studies pointed to unexpected roles for loss of function mutations in Cblb and Myb in B cell transformation. Subsequent RNA-Seq studies on WT, Pax5+/-, Ebf1+/-, Pax5+/- x Ebf1+/- pre-leukemic, Pax5+/- x Ebf1+/- leukemic cells and Pax5+/- x Ebf1+/- Sleeping Beauty leukemic cells demonstrated upregulation of a PDK1>SGK3>MYC pathway; treatment of Pax5+/- x Ebf1+/- leukemias with PDK1 specific inhibitors blocked their proliferation in vitro. Finally, we identified conserved transcriptional variation in a subset of genes between human leukemias and our mouse B-ALL models. Thus, compound haploinsufficiency for B cell transcription factors likely plays a critical role in transformation of human B cells and suggest that newly developed PDK1 inhibitors may be effective for treating patients characterized by such defects.
Project description:PURPOSE: To provide a detailed gene expression profile of the normal postnatal mouse cornea. METHODS: Serial analysis of gene expression (SAGE) was performed on postnatal day (PN)9 and adult mouse (6 week) total corneas. The expression of selected genes was analyzed by in situ hybridization. RESULTS: A total of 64,272 PN9 and 62,206 adult tags were sequenced. Mouse corneal transcriptomes are composed of at least 19,544 and 18,509 unique mRNAs, respectively. One third of the unique tags were expressed at both stages, whereas a third was identified exclusively in PN9 or adult corneas. Three hundred thirty-four PN9 and 339 adult tags were enriched more than fivefold over other published nonocular libraries. Abundant transcripts were associated with metabolic functions, redox activities, and barrier integrity. Three members of the Ly-6/uPAR family whose functions are unknown in the cornea constitute more than 1% of the total mRNA. Aquaporin 5, epithelial membrane protein and glutathione-S-transferase (GST) omega-1, and GST alpha-4 mRNAs were preferentially expressed in distinct corneal epithelial layers, providing new markers for stratification. More than 200 tags were differentially expressed, of which 25 mediate transcription. CONCLUSIONS: In addition to providing a detailed profile of expressed genes in the PN9 and mature mouse cornea, the present SAGE data demonstrate dynamic changes in gene expression after eye opening and provide new probes for exploring corneal epithelial cell stratification, development, and function and for exploring the intricate relationship between programmed and environmentally induced gene expression in the cornea. Keywords: other
Project description:EBF1 and PAX5 are two transcription factors targeted in human B-ALL. Their importance for normal B-cell differentiation has led to the suggestion that impaired function of these proteins contributes to the developmental block observed in B-lineage leukemia. However, increased understanding of the function of these proteins has suggested more complex roles in malignant transformation. We here report that the loss of EBF1 function in B-cell progenitors results in reduced expression of c-MYC. Ectopic expression of c-MYC rescues B-cell expansion in the absence of EBF1 both in vivo and in vitro and ChIP-seq analysis identifies multiple binding sites for EBF1 in putative regulatory elements of the mouse c-Myc gene. On the contrary, expression of PAX5 in EBF1 deficient cells resulted in down regulation of c-Myc and inhibition of cell expansion. Since both EBF1 and PAX5 bind multiple regulatory elements in the c-Myc gene, these data suggest that EBF1 and PAX5 have opposing functions with regard to regulation of c-Myc expression. This suggests the existence of a lineage restricted regulatory loop controlling the expansion of B-lineage progenitors. The binding of EBF1 and PAX5 to multiple regulatory elements in the human c-MYC gene indicate that this regulatory loop may be of relevance for our understanding of leukemia formation.