Molecular mechanisms that are responsible for the development of human skin epithelial cells are not completely understood so far. As a consequence, the efficiency to establish a pure skin epithelial cell population from human induced pluripotent stem cells (hiPSC) remains poor. Using an approach including RNA interference and high-throughput imaging of early epithelial cells, we could identify candidate kinases which are involved in skin epithelial differentiation. Among them, we found HIPK4 to be an important inhibitor of this process. Indeed, its silencing increased the amount of generated skin epithelial precursors, increased the amount of generated keratinocytes and improved growth and differentiation of organotypic cultures, allowing for the formation of a denser basal layer and stratification with the expression of several keratins. Our data bring substantial input in the regulation of human skin epithelial differentiation and for improving differentiation protocols from pluripotent stem cells.
An RNAi Screen Reveals an Essential Role for HIPK4 in Human Skin Epithelial Differentiation from iPSCs.
Specimen part, Time
View SamplesThe aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor involved in adaptive cell functions, and highly active in the epidermis. AhR-ligands can accelerate keratinocyte differentiation, but a precise role for AhR in the skin barrier is unknown. We here show that transepidermal water loss (TEWL), a parameter of skin barrier integrity, is high in AhR-deficient (AhR-KO) mice. Experiments with conditionally AhR-deficient mouse lines identified keratinocytes as the major responsible cell population for high TEWL. Electron microscopy showed weaker inter-cellular connectivity in the epidermis of keratinocytes in AhR-KO mice, and gene expression analysis identified many barrier-associated genes as AhR targets. Moreover, AhR-deficient mice had higher inter-individual differences in their microbiome. Interestingly, removing AhR-ligands from the diet of wild-type mice mimicked AhR-deficiency regarding the impaired barrier. Vice versa, re-addition of the plant-derived ligand indole-3-carbinol (I3C) rescued the barrier deficiency even in aged mice. Our results suggest that functional AhR expression is critical for skin barrier integrity and that AhR represents a molecular target for the development of novel therapeutic approaches for skin barrier diseases, including dietary intervention.
Aryl Hydrocarbon Receptor in Keratinocytes Is Essential for Murine Skin Barrier Integrity.
Sex, Specimen part, Treatment, Time
View SamplesIn this series we have analyzed the effect of donor age on the gene expression profile of mesenchymal stromal cells (alternatively named mesenchymal stem cells; MSC) from human bone marrow. Cells were taken from bone marrow aspirates from iliac crest (BM) of healthy donors or from the caput femoris (HIP) of elderly patients that received femoral head prosthesis.
Aging and replicative senescence have related effects on human stem and progenitor cells.
No sample metadata fields
View SamplesWe 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.
Transcriptional repression of Gata3 is essential for early B cell commitment.
Specimen part
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 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 SamplesGene expression analysis of purified thymopoiesis-initiating progenitors/early thymic progenitors, lymphoid primed multipotent progenitors (LMPP) and hematopoietic stem/progenitor cells from E11.5, E12.5, E13.5 embryos, neonatal (1 week old) and adult (8 weeks old) mice Overall design: Differentially expressed genes analysis
Initial seeding of the embryonic thymus by immune-restricted lympho-myeloid progenitors.
Specimen part, Cell line, Subject
View SamplesLung alveolarization is a complex process that involves interactions between several cell types and leads to considerable increase in gas-exchange surface area. The step designated secondary septation includes elastogenesis from interstitial fibroblasts.
Gene expression profiling in lung fibroblasts reveals new players in alveolarization.
No sample metadata fields
View SamplesGene expression analysis of early thymic progenitors and thymus seeding progenitors
The earliest thymic T cell progenitors sustain B cell and myeloid lineage potential.
Sex, Age, Specimen part, Disease
View SamplesAnalysis of HEK293 cells lines expressing V336Y mutant mitochondrial ribosomal protein. Overall design: mRNA profiles of wild-type and V336Y mutant HEK293 cell culture samples generated by deep sequencing.
Mutant MRPS5 affects mitoribosomal accuracy and confers stress-related behavioral alterations.
Cell line, Subject
View Samples