Understanding the specific cell populations responsible for propagation of leukemia is an important step for development of effective targeted therapies. Recently, the lymphoid-primed multipotent progenitor (LMPP) has been proposed to be a key propagating population in acute myeloid leukemia (AML; PMID 21251617). We have also shown that LMPPs share many functional and gene expression properties with early thymic progenitors (ETPs; PMID 22344248). This finding is of particular interest as ETP leukemias have recently been described: a distinct and poor prognostic disease entity with a transcriptional profile reminiscent of murine ETPs, showing co-expression of hematopoietic stem cell (HSC) and myeloid markers (PMID 19147408). Together, this raises the question whether ETPs can act as a leukemia-initiating/propagating cell population; however, relevant disease models to test this hypothesis are currently lacking. Analysis of the genetic landscape of ETP leukemias has revealed frequent coexistence of inactivating mutations of EZH2 and RUNX1 (PMID 22237106). We therefore generated mice with deletions of Ezh2 and Runx1 specifically targeted to early lymphoid progenitors using Rag1Cre (Ezh2fl/flRunx1fl/flRag1Cre+; DKO mice). As anticipated, HSCs lacked significant recombination in DKO mice whereas close to 100% of purified ETPs (Lin-CD4-CD8-CD44+CD25-Kit+Flt3+) showed deletion of Ezh2 and Runx1. Strikingly, despite a 16-fold reduction in thymus cellularity caused by a block in thymocyte maturation at the DN2-DN3 transition, absolute numbers of ETPs within the thymus of DKO mice were markedly expanded (12-fold; p<0.0001). In contrast, Ezh2 or Runx1 deletion alone had no impact on numbers of ETPs. RNA-sequencing of the expanded ETPs in DKO mice revealed upregulation of HSC- and myeloid-associated transcriptional programs, reminiscent of ETP leukaemia e.g. Pbx1 (log2FC=3.0; p<0.0001) and Csf3r (log2FC=1.9; p=0.0038). Single-cell gene expression analysis confirmed co-expression of HSC and myeloid programs with lymphoid genes within individual DKO ETPs. Further, some key regulators of T-cell maturation which are aberrantly expressed in ETP leukemia were also disrupted in DKO ETPs e.g. Tcf7 (log2FC=-9.5; p<0.0001). Gene expression associated with aberrant Ras signalling was also present. However, despite a continued expansion of the ETP population with age, we did not observe leukemia in DKO mice with over 1 year of follow-up. Since ETP leukemias frequently feature activating mutations in genes regulating RAS signaling, we hypothesised that the expanded “pre-leukemic” ETPs in DKO mice would be primed for leukemic transformation by signalling pathway mutation. We therefore crossed DKO mice with a Flt3ITD/+ knock-in mouse line, as internal tandem duplications (ITD) of FLT3 are frequent in ETP leukemias. Ezh2fl/flRunx1fl/flRag1Cre+Flt3ITD/+ (DKOITD) mice showed dramatically reduced survival (median 9.3 weeks) resulting from an aggressive, fully penetrant acute leukemia showing a predominantly myeloid phenotype (e.g. Mac1) but with co-expression of some lymphoid antigens (e.g. intracellular CD3). Crucially, this leukaemia could be propagated in wild-type recipients upon transplantation of the expanded ETPs. DKOITD ETPs were transcriptionally very similar to DKO ETPs, retaining expression of lymphoid alongside HSC- and myeloid-associated genes. Finally, in a lympho-myeloid cell line model (EML cells) we demonstrated that Ezh2 inactivation-induced loss of H3K27me3 is associated with a corresponding increase in H3K27Ac, a transcriptional activating signal that recruits bromodomain proteins. As such, we reasoned that our ETP leukemia model might be sensitive to bromodomain inhibitors such as JQ1. Indeed, we observed high sensitivity of expanded DKOITD ETPs to JQ1, raising the possibility of a new therapeutic approach for ETP leukemias. This novel mouse model of ETP-propagated leukemia, driven by clinically relevant mutations, provides intriguing evidence that leukemias with a predominant myeloid phenotype, but co-expressing lymphoid genes, may initiate within a bona fide early lymphoid progenitor population. Since the functional characteristics of the cell of origin of a leukaemia may direct its progression and response to therapy, these findings could have important implications for future stratification and treatment of both AML and ETP leukemias. Overall design: mRNA-sequencing of mouse Mac1+ bone marrow cells from three genotypes
Ezh2 and Runx1 Mutations Collaborate to Initiate Lympho-Myeloid Leukemia in Early Thymic Progenitors.
Cell line, Subject
View SamplesUnderstanding the specific cell populations responsible for propagation of leukemia is an important step for development of effective targeted therapies. Recently, the lymphoid-primed multipotent progenitor (LMPP) has been proposed to be a key propagating population in acute myeloid leukemia (AML; PMID 21251617). We have also shown that LMPPs share many functional and gene expression properties with early thymic progenitors (ETPs; PMID 22344248). This finding is of particular interest as ETP leukemias have recently been described: a distinct and poor prognostic disease entity with a transcriptional profile reminiscent of murine ETPs, showing co-expression of hematopoietic stem cell (HSC) and myeloid markers (PMID 19147408). Together, this raises the question whether ETPs can act as a leukemia-initiating/propagating cell population; however, relevant disease models to test this hypothesis are currently lacking. Analysis of the genetic landscape of ETP leukemias has revealed frequent coexistence of inactivating mutations of EZH2 and RUNX1 (PMID 22237106). We therefore generated mice with deletions of Ezh2 and Runx1 specifically targeted to early lymphoid progenitors using Rag1Cre (Ezh2fl/flRunx1fl/flRag1Cre+; DKO mice). As anticipated, HSCs lacked significant recombination in DKO mice whereas close to 100% of purified ETPs (Lin-CD4-CD8-CD44+CD25-Kit+Flt3+) showed deletion of Ezh2 and Runx1. Strikingly, despite a 16-fold reduction in thymus cellularity caused by a block in thymocyte maturation at the DN2-DN3 transition, absolute numbers of ETPs within the thymus of DKO mice were markedly expanded (12-fold; p<0.0001). In contrast, Ezh2 or Runx1 deletion alone had no impact on numbers of ETPs. RNA-sequencing of the expanded ETPs in DKO mice revealed upregulation of HSC- and myeloid-associated transcriptional programs, reminiscent of ETP leukaemia e.g. Pbx1 (log2FC=3.0; p<0.0001) and Csf3r (log2FC=1.9; p=0.0038). Single-cell gene expression analysis confirmed co-expression of HSC and myeloid programs with lymphoid genes within individual DKO ETPs. Further, some key regulators of T-cell maturation which are aberrantly expressed in ETP leukemia were also disrupted in DKO ETPs e.g. Tcf7 (log2FC=-9.5; p<0.0001). Gene expression associated with aberrant Ras signalling was also present. However, despite a continued expansion of the ETP population with age, we did not observe leukemia in DKO mice with over 1 year of follow-up. Since ETP leukemias frequently feature activating mutations in genes regulating RAS signaling, we hypothesised that the expanded “pre-leukemic” ETPs in DKO mice would be primed for leukemic transformation by signalling pathway mutation. We therefore crossed DKO mice with a Flt3ITD/+ knock-in mouse line, as internal tandem duplications (ITD) of FLT3 are frequent in ETP leukemias. Ezh2fl/flRunx1fl/flRag1Cre+Flt3ITD/+ (DKOITD) mice showed dramatically reduced survival (median 9.3 weeks) resulting from an aggressive, fully penetrant acute leukemia showing a predominantly myeloid phenotype (e.g. Mac1) but with co-expression of some lymphoid antigens (e.g. intracellular CD3). Crucially, this leukaemia could be propagated in wild-type recipients upon transplantation of the expanded ETPs. DKOITD ETPs were transcriptionally very similar to DKO ETPs, retaining expression of lymphoid alongside HSC- and myeloid-associated genes. Finally, in a lympho-myeloid cell line model (EML cells) we demonstrated that Ezh2 inactivation-induced loss of H3K27me3 is associated with a corresponding increase in H3K27Ac, a transcriptional activating signal that recruits bromodomain proteins. As such, we reasoned that our ETP leukemia model might be sensitive to bromodomain inhibitors such as JQ1. Indeed, we observed high sensitivity of expanded DKOITD ETPs to JQ1, raising the possibility of a new therapeutic approach for ETP leukemias. This novel mouse model of ETP-propagated leukemia, driven by clinically relevant mutations, provides intriguing evidence that leukemias with a predominant myeloid phenotype, but co-expressing lymphoid genes, may initiate within a bona fide early lymphoid progenitor population. Since the functional characteristics of the cell of origin of a leukaemia may direct its progression and response to therapy, these findings could have important implications for future stratification and treatment of both AML and ETP leukemias. Overall design: mRNA-sequencing of mouse early thymic precursors from three genotypes
Ezh2 and Runx1 Mutations Collaborate to Initiate Lympho-Myeloid Leukemia in Early Thymic Progenitors.
Cell line, Subject
View SamplesThe human nuclear poly(A)-binding protein PABPN1 has been implicated in the decay of nuclear noncoding RNAs (ncRNAs). In addition, PABPN1 stimulates hyperadenylation by poly(A) polymerase, and this activity is thought to be required for decay. Here, we inactivated hyperadenylation by two distinct mechanisms and examined changes in gene expression in HEK293 cells by RNAseq. We observed the upregulation of various ncRNAs, including snoRNA host genes, primary miRNA transcripts, and upstream antisense RNAs, confirming that hyperadenylation is broadly required for the degradation of PABPN1-targets. In addition, we found that mRNAs with retained introns are susceptible to PABPN1 and PAPa/?-mediated decay (PPD). Transcripts are targeted for degradation due to inefficient export, which is a consequence of reduced intron number or incomplete splicing. We conclude that PPD is an important mammalian nuclear RNA decay pathway for the removal of poorly spliced and nuclear-retained transcripts. Overall design: Poly(A)+ RNA from HEK293 cells was analyzed by next generation sequencing following depletion of PAPa and PAP? or expression of a dominant negative allele of PABPN1 (LALA) designed to inhibit polyadenylation. For each condition, we collected both total RNA and a nuclear-enriched sample. Each sample was collected in duplicate.
Canonical Poly(A) Polymerase Activity Promotes the Decay of a Wide Variety of Mammalian Nuclear RNAs.
No sample metadata fields
View SamplesThe RING domain protein Arkadia/RNF111 is a ubiquitin ligase in the transforming growth factor beta (TGFß) pathway. We previously identified Arkadia as a small ubiquitin-like modifier (SUMO)-binding protein with clustered SUMO-interacting motifs (SIMs) that together form a SUMO-binding domain (SBD). However, precisely how SUMO interaction contributes to the function of Arkadia was not resolved. Through analytical molecular and cell biology, we found that the SIMs share redundant function with Arkadia''s M domain, a region distinguishing Arkadia from its paralogs ARKL1/ARKL2 and the prototypical SUMO-targeted ubiquitin ligase (STUbL) RNF4. The SIMs and M domain together promote both Arkadia''s colocalization with CBX4/Pc2, a component of Polycomb bodies, and the activation of a TGFbeta pathway transcription reporter. Transcriptome profiling through RNA sequencing showed that Arkadia can both promote and inhibit gene expression, indicating that Arkadia''s activity in transcriptional control may depend on the epigenetic context, defined by Polycomb repressive complexes and DNA methylation [Sun, Liu, and Hunter (2014) Mol Cell Biol 34(16):2981-2995]. Overall design: To determine the role of Arkadia in TGFß signaling at the transcriptome level, the profiles of TGFß-stimulated gene expression were examined in Ark+/+ (Ark_WT), Ark-/- (Ark_null), and Arkadia (WT and sim mutant)-reconstituted Ark-/- MEFs. RNA sequencing was carried out using poly(A)-enriched RNA samples from unstimulated cells and cells treated with TGFß for 1h, 4h, or 16h as indicated. Two batches of sequencing data for a total of 16 independent samples were submitted.
Multiple Arkadia/RNF111 structures coordinate its Polycomb body association and transcriptional control.
No sample metadata fields
View SamplesThis study was aimed at understanding the genome-wide binding and regulatory role of the DAXX transcriptional repressor, recently implicated in PCa. ChIP-Seq analysis of genome-wide distribution of DAXX in PC3 cells revealed over 59,000 DAXX binding sites, found at regulatory enhancers and promoters. ChIP-Seq analysis of DNA methyltransferase 1 (DNMT1), which is a key epigenetic partner for DAXX repression, revealed that DNMT1 binding was restricted to a small number of DAXX sites. DNMT1 and DAXX bound close to transcriptional activator motifs. DNMT1 sites were found to be dependent on DAXX for recruitment by analyzing DNMT1 ChIP-Seq following DAXX knockdown (K/D), corroborating previous findings that DAXX recruits DNMT1 to repress its target genes. Massively parallel RNA sequencing (RNA-Seq) was used to compare the transcriptomes of WT and DAXX K/D PC3 cells. Genes induced by DAXX K/D included those involved in autophagy, and DAXX ChIP-Seq peaks were found close to the transcription start sites (TSS) of autophagy genes, implying they are more likely to be regulated by DAXX. Overall design: Determine changes in gene expression levels between WT and DAXX K/D prostate cancer cells by RNA-Seq (PC3 Cells).
The DAXX co-repressor is directly recruited to active regulatory elements genome-wide to regulate autophagy programs in a model of human prostate cancer.
No sample metadata fields
View SamplesThis SuperSeries is composed of the SubSeries listed below.
The origins of breast cancer prognostic gene expression profiles.
No sample metadata fields
View SamplesMetastasis predictive gene signatures can result from either somatic mutation, inherited polyrmorphism or both. This experiment is designed to look at the gene expression differences due to differences in somatic mutations in the initiating oncogene, PyMT. Met1 is from a fully metastatic FVB mammary tumor cell line, DB7 contains a mutation that permits tumor formation, but suppresses metastatic ability.
The origins of breast cancer prognostic gene expression profiles.
No sample metadata fields
View SamplesF1 hybrids from (AKR/J x FVB/NJ) and (DBA/2J x FVB/NJ) outcrosses display a 20-fold difference in mammary tumor metastatic capacity, due to differences in inherited polymorphisms. Expression studies were performed to determine whether polymorphism-driven gene expression signatures predictive of outcome could be generated from normal tissues
The origins of breast cancer prognostic gene expression profiles.
No sample metadata fields
View SamplesF1 hybrids from (AKR/J x FVB/NJ) and (DBA/2J x FVB/NJ) outcrosses display a 20-fold difference in mammary tumor metastatic capacity, due to differences in inherited polymorphisms. Expression studies were performed to determine whether polymorphism-driven gene expression signatures predictive of outcome could be generated from mouse tumor tissues
The origins of breast cancer prognostic gene expression profiles.
No sample metadata fields
View SamplesF1 hybrids from (AKR/J x FVB/NJ) and (DBA/2J x FVB/NJ) outcrosses display a 20-fold difference in mammary tumor metastatic capacity, due to differences in inherited polymorphisms. Expression studies were performed to determine whether polymorphism-driven gene expression signatures predictive of outcome could be generated from normal tissues
The origins of breast cancer prognostic gene expression profiles.
No sample metadata fields
View Samples