Project description:Polycomb group (PcG) proteins comprise a large group of evolutionary conserved factors with essential roles for embryonic development and adult stem cell function. PcG proteins constitute two main multiprotein polycomb repressive complexes (PRC1 and PRC2) that operate in a hierarchical manner to silence gene expression. Functionally distinct PRC1 complexes are defined by Polycomb group RING finger protein (PCGF) paralogs. So far, six PCGF paralogs (PCGF1-6) have been identified but paralog-specific functions are not well understood. In our studies, we observed that Pcgf6 showed the highest expression level in undifferentiated murine embryonic stem cells (ESCs), blastocysts and testes. When ESCs differentiated, Pcgf6 expression strongly declined. To further investigate Pcgf6 biology, we established dox-inducible shRNA knockdown (KD) ESCs. Following Pcgf6 KD in ESCs the expression of pluripotency genes decreased, while mesodermal- and spermatogenesis-specific genes were de-repressed. Concomitantly with the elevated expression of mesodermal lineage markers, Pcgf6 KD ESCs showed increased hemangioblastic and hematopoietic activities. Finally, PCGF6 replaced SOX2 but not KLF4 or c-MYC in the generation of germline-competent iPS cells. Forced expression of Pcgf6 in OSKM-driven reprogramming increases iPS efficiency while Pcgf6 KD reduces the formation of ESC-like colonies. Together, these analyses show that Pcgf6 is non-redundantly involved in maintaining the pluripotent nature of ESCs and functions in iPS reprogramming. 6 samples were hybridized GeneChip Mouse Gene 1.0 ST Arrays (Affymetrix)
Project description:Polycomb group (PcG) proteins comprise a large group of evolutionary conserved factors with essential roles for embryonic development and adult stem cell function. PcG proteins constitute two main multiprotein polycomb repressive complexes (PRC1 and PRC2) that operate in a hierarchical manner to silence gene expression. Functionally distinct PRC1 complexes are defined by Polycomb group RING finger protein (PCGF) paralogs. So far, six PCGF paralogs (PCGF1-6) have been identified but paralog-specific functions are not well understood. In our studies, we observed that Pcgf6 showed the highest expression level in undifferentiated murine embryonic stem cells (ESCs), blastocysts and testes. When ESCs differentiated, Pcgf6 expression strongly declined. To further investigate Pcgf6 biology, we established dox-inducible shRNA knockdown (KD) ESCs. Following Pcgf6 KD in ESCs the expression of pluripotency genes decreased, while mesodermal- and spermatogenesis-specific genes were de-repressed. Concomitantly with the elevated expression of mesodermal lineage markers, Pcgf6 KD ESCs showed increased hemangioblastic and hematopoietic activities. Finally, PCGF6 replaced SOX2 but not KLF4 or c-MYC in the generation of germline-competent iPS cells. Forced expression of Pcgf6 in OSKM-driven reprogramming increases iPS efficiency while Pcgf6 KD reduces the formation of ESC-like colonies. Together, these analyses show that Pcgf6 is non-redundantly involved in maintaining the pluripotent nature of ESCs and functions in iPS reprogramming.
Project description:We report that the PRC1 component polycomb group ring finger 6 (Pcgf6) is required to maintain embryonic stem cell (ESC) identity. In contrast to canonical PRC1, Pcgf6 acts as a positive regulator of transcription and binds predominantly to promoters bearing active chromatin marks. Pcgf6 is expressed at high levels in ESCs, and knockdown reduces the expression of the core ESC regulators Oct4,Sox2, and Nanog. Conversely, Pcgf6 overexpression prevents downregulation of these factors and impairs differentiation. In addition, Pcgf6 enhanced reprogramming in both mouse and human somatic cells. The genomic binding profile of Pcgf6 is highly similar to that of trithorax group proteins, but not of PRC1 or PRC2 complexes, suggesting that Pcgf6 functions atypically in ESCs. Our data reveal novel roles for Pcgf6 in directly regulating Oct4, Nanog, Sox2, and Lin28 expression to maintain ESC identity. To identify Pcgf6-bound genomic DNA regions in mouse embryonic stem cells, we fixed mouse ESCs and isolated Pcgf6-bound genomic DNA regions for deep sequencing analysis.
Project description:The Polycomb group (PcG) proteins have an important role in controlling the expression of key genes implicated in embryonic development, differentiation and decision of cell fates. Emerging evidence suggests that Polycomb repressive complexes 1 (PRC1) is defined by the six Polycomb group RING finger protein (Pcgf) paralogs and Pcgf proteins can assemble into noncanonical PRC1 complexes. However, little is known about the precise mechanisms of differently composed noncanonical PRC1 in the maintenance of the pluripotent cell state. Here we disrupt the Pcgf genes in mouse embryonic stem cells by CRISPR-Cas9 to investigate Pcgf6 function. Microarray experiments were performed using wildtype ,Pcgf6 KO and Pcgf6 KO + Pcgf6_flag ES cells.
Project description:We report that the PRC1 component polycomb group ring finger 6 (Pcgf6) is required to maintain embryonic stem cell (ESC) identity. In contrast to canonical PRC1, Pcgf6 acts as a positive regulator of transcription and binds predominantly to promoters bearing active chromatin marks. Pcgf6 is expressed at high levels in ESCs, and knockdown reduces the expression of the core ESC regulators Oct4,Sox2, and Nanog. Conversely, Pcgf6 overexpression prevents downregulation of these factors and impairs differentiation. In addition, Pcgf6 enhanced reprogramming in both mouse and human somatic cells. The genomic binding profile of Pcgf6 is highly similar to that of trithorax group proteins, but not of PRC1 or PRC2 complexes, suggesting that Pcgf6 functions atypically in ESCs. Our data reveal novel roles for Pcgf6 in directly regulating Oct4, Nanog, Sox2, and Lin28 expression to maintain ESC identity.
Project description:Polycomb group (PcG) proteins are essential for maintenance of lineage fidelity by coordinating developmental gene expression programs. Polycomb group protein Pcgf6 has been previously reported to repress lineage-specific genes, especially germ cell-related genes in mouse embryonic stem cells (ESCs) via the non- canonical Polycomb repressive complex PRC1. 6. However, the potential mechanism of this repressive activity remains largely unknown. Here, we demonstrated that Pcgf6 played an essential role in embryonic development as indicated by the partially penetrant embryonic lethality in homozygous mice. Additionally, we found that surviving Pcgf6-deficient mice exhibited compromised fertility. Using the Pcgf6 mutant mice, we revealed that ablation of Pcgf6 in somatic tissues also led to robust derepression of such germ cell-related genes. We provided evidence that these genes were direct targets of Pcgf6 in ESCs and endogenous Pcgf6 colocalized with G9a/Glp and Hdac1/2 on the promoters of these germ cell-related genes and that binding of these proteins to target genes correlated with methylation of H3K9 and the status of histone acetylation. Moreover, the recruitment of G9a/Glp and Hdac1/2 to target promoters was dependent on the binding of Pcgf6. Therefore, our study demonstrated a critical role for Pcgf6 in safeguarding lineage decisions and in protecting germ cell-related genes against aberrant expression.
Project description:Whole genome sequencing was performed on several murine iPS cell clones (and their parental cells) from each of three independent reprogramming experiments. Hundreds of single nucleotide variants (SNVs) were detected in each clone, with an average of 11 in coding regions. Affymetrix Mouse Exon 1.0ST arrays were used to compare expression patterns in MPSVII iPS lines, and embryo-derived MPSVII ES cells. Unsupervised hierarchal clustering analysis showed that the iPS clones and ES cell lines clustered randomly, suggesting that their global patterns of gene expression are highly similar. Taken together, our data suggest that most of the genetic variation in iPS cell clones is not caused by reprogramming, but is rather a consequence of cloning individual cells, “capturing” random mutations that preexisted in the single cells that were reprogrammed. These mutations can sometimes contribute to reprogramming “fitness”, thus providing a selective advantage for rare cells when they overexpress reprogramming factors. Mouse embryonic fibroblasts (MEFs) derived from a murine disease model (Mucopolysaccaridosis type VII- MPSVII) were used. Affymetrix Mouse Exon 1.0ST arrays were used to compare expression patterns in MPSVII iPS lines, and embryo-derived MPSVII ES cells. Expression patterns in four separate iPS clones were compared to MPSVII ES cells. Control hybridization was performed with B6 Blu ES cells and MEFs.
Project description:Hematopoiesis generated from human embryonic stem cells (ES) and induced pluripotent stem cells (iPS) are unprecedented resources for cell therapy. We compared hematopoietic differentiation potentials from ES and iPS cell lines originated from various donors and derived them using integrative and non-integrative vectors. Significant differences in differentiation toward hematopoietic lineage were observed among ES and iPS. The ability of engraftment of iPS or ES-derived cells in NOG mice varied among the lines with low levels of chimerism. iPS generated from ES cell-derived mesenchymal stem cells (MSC) reproduce a similar hematopoietic outcome compared to their parental ES cell line. We were not able to identify any specific hematopoietic transcription factors that allow to distinguish between good versus poor hematopoiesis in undifferentiated ES or iPS cell lines. However, microarray analysis showed genes differentially expressed in ES and iPS cell lines according to their hematopoietic potential. These results demonstrate the influence of genetic background in variation of hematopoietic potential rather than the reprogramming process.
Project description:We identified that DC activation and immunogenicity are regulated by the transcriptional repressor polycomb group factor 6 (PCGF6). Pcgf6 is rapidly downregulated upon stimulation and this downregulation is necessary to permit full DC activation. Silencing PCGF6 expression enhanced both spontaneous and stimulated DC activation. We show that PCGF6 associates with the H3K4me3 demethylase JARID1c, and together they negatively regulate H3K4me3 levels in DCs. Our results identify two key regulators – PCGF6 and JARID1c – that temper DC activation, and implicate active transcriptional silencing via histone demethylation as a previously unappreciated mechanism for regulating DC activation and quiescence
Project description:Whole genome sequencing was performed on several murine iPS cell clones (and their parental cells) from each of three independent reprogramming experiments. Hundreds of single nucleotide variants (SNVs) were detected in each clone, with an average of 11 in coding regions. Affymetrix Mouse Exon 1.0ST arrays were used to compare expression patterns in MPSVII iPS lines, and embryo-derived MPSVII ES cells. Unsupervised hierarchal clustering analysis showed that the iPS clones and ES cell lines clustered randomly, suggesting that their global patterns of gene expression are highly similar. Taken together, our data suggest that most of the genetic variation in iPS cell clones is not caused by reprogramming, but is rather a consequence of cloning individual cells, “capturing” random mutations that preexisted in the single cells that were reprogrammed. These mutations can sometimes contribute to reprogramming “fitness”, thus providing a selective advantage for rare cells when they overexpress reprogramming factors.