Project description:Epigenetic regulation of chromatin states is thought to control the self-renewal and differentiation of embryonic stem (ES) cells. However, the roles of repressive histone modifications such as trimethylated histone lysine 20 (H4K20me3) in pluripotency and development are largely unknown. Here, we show that the histone lysine methyltransferase SMYD5 mediates H4K20me3 at heterochromatin regions. Depletion of SMYD5 leads to compromised self-renewal, including dysregulated expression of OCT4 targets, and perturbed differentiation. SMYD5 bound regions are enriched with repetitive DNA elements. Knockdown of SMYD5 results in a global decrease of H4K20me3 levels, a redistribution of heterochromatin constituents including H3K9me3/2, G9a, and HP1α, and de-repression of endogenous retroelements. A loss of SMYD5-dependent silencing of heterochromatin nearby genic regions leads to upregulated expression of lineage-specific genes, thus contributing to the decreased self-renewal and accelerated differentiation of SMYD5-depeleted ES cells. Altogether, these findings implicate a role for SMYD5 in regulating ES cell self-renewal and H4K20me3-marked heterochromatin.
Project description:Epigenetic regulation of chromatin states is thought to control the self-renewal and differentiation of embryonic stem (ES) cells. However, the roles of repressive histone modifications such as trimethylated histone lysine 20 (H4K20me3) in pluripotency and development are largely unknown. Here, we show that the histone lysine methyltransferase SMYD5 mediates H4K20me3 at heterochromatin regions. Depletion of SMYD5 leads to compromised self-renewal, including dysregulated expression of OCT4 targets, and perturbed differentiation. SMYD5 bound regions are enriched with repetitive DNA elements. Knockdown of SMYD5 results in a global decrease of H4K20me3 levels, a redistribution of heterochromatin constituents including H3K9me3/2, G9a, and HP1α, and de-repression of endogenous retroelements. A loss of SMYD5-dependent silencing of heterochromatin nearby genic regions leads to upregulated expression of lineage-specific genes, thus contributing to the decreased self-renewal and accelerated differentiation of SMYD5-depeleted ES cells. Altogether, these findings implicate a role for SMYD5 in regulating ES cell self-renewal and H4K20me3-marked heterochromatin.
Project description:Epigenetic regulation of chromatin states is thought to control gene expression programs during lineage specification. However, the roles of repressive histone modifications such as trimethylated histone lysine 20 (H4K20me3) in development and genome stability are largely unknown. Here, we show that depletion of SMYD5, a H4K20me3 methyltransferase, leads to decreased H4K20me3 and H3K9me3 ChIP-Seq levels, and de-repression of endogenous LTR/LINE elements during differentiation. SMYD5 depletion results in chromosomal aberrations and the formation of transformed cells that exhibit decreased H4K20me3 and H3K9me3 levels and an expression signature consistent with multiple human cancers. Moreover, dysregulated gene expression in SMYD5 cancer cells is associated with LTR/ERV elements and decreased H4K20me3. These findings implicate an important role for SMYD5 in maintaining chromosome integrity by regulating heterochromatin and repressing endogenous repetitive DNA elements during differentiation.
Project description:Epigenetic regulation of chromatin states is thought to control gene expression programs during lineage specification. However, the roles of repressive histone modifications such as trimethylated histone lysine 20 (H4K20me3) in development and genome stability are largely unknown. Here, we show that depletion of SMYD5, a H4K20me3 methyltransferase, leads to decreased H4K20me3 and H3K9me3 ChIP-Seq levels, and de-repression of endogenous LTR/LINE elements during differentiation. SMYD5 depletion results in chromosomal aberrations and the formation of transformed cells that exhibit decreased H4K20me3 and H3K9me3 levels and an expression signature consistent with multiple human cancers. Moreover, dysregulated gene expression in SMYD5 cancer cells is associated with LTR/ERV elements and decreased H4K20me3. These findings implicate an important role for SMYD5 in maintaining chromosome integrity by regulating heterochromatin and repressing endogenous repetitive DNA elements during differentiation.
Project description:Heterochromatin, which is a densely packed chromatin state that is transcriptionally silent, is a critical regulator of gene expression. However, it is unclear how the repressive histone modification, H4K20me3, or the histone methyltransferase, SUV420H2, regulate embryonic stem (ES) cell fate by patterning the epigenetic landscape. Here, we report that depletion of SUV420H2 leads to a near complete loss of H4K20me3 genome-wide, dysregulated gene expression, and delayed ES cell differentiation. SUV420H2-bound regions are enriched with repetitive DNA elements, which are de-repressed in SUV420H2 knockout ES cells. Moreover, SUV420H2 regulation of H4K20me3-marked heterochromatin controls chromatin architecture, including fine-scale interactions between gene regulatory elements in pluripotent ES cells. SUV420H2 plays a critical role in stabilizing the three-dimensional (3D) chromatin landscape of ES cells, where loss of SUV420H2 results in A/B compartment switching, perturbed chromatin insulation, and altered chromatin interactions of pericentric heterochromatin, indicative of localized decondensation. In addition, depletion of SUV420H2 resulted in compromised interactions between H4K20me3 and gene regulatory regions. Together, these findings describe a novel role for SUV420H2 in regulating the chromatin landscape of ES cells.
Project description:Heterochromatin, which is a densely packed chromatin state that is transcriptionally silent, is a critical regulator of gene expression. However, it is unclear how the repressive histone modification, H4K20me3, or the histone methyltransferase, SUV420H2, regulate embryonic stem (ES) cell fate by patterning the epigenetic landscape. Here, we report that depletion of SUV420H2 leads to a near complete loss of H4K20me3 genome-wide, dysregulated gene expression, and delayed ES cell differentiation. SUV420H2-bound regions are enriched with repetitive DNA elements, which are de-repressed in SUV420H2 knockout ES cells. Moreover, SUV420H2 regulation of H4K20me3-marked heterochromatin controls chromatin architecture, including fine-scale interactions between gene regulatory elements in pluripotent ES cells. SUV420H2 plays a critical role in stabilizing the three-dimensional (3D) chromatin landscape of ES cells, where loss of SUV420H2 results in A/B compartment switching, perturbed chromatin insulation, and altered chromatin interactions of pericentric heterochromatin, indicative of localized decondensation. In addition, depletion of SUV420H2 resulted in compromised interactions between H4K20me3 and gene regulatory regions. Together, these findings describe a novel role for SUV420H2 in regulating the chromatin landscape of ES cells.
Project description:Regulation of genes that initiate and amplify inflammatory programs of gene expression is achieved by signal-dependent exchange of co-regulator complexes that function to read, write and erase specific histone modifications linked to transcriptional activation or repression. Here, we provide evidence for an unexpected role of trimethylated histone H4 lysine 20 (H4K20me3) as a repression checkpoint that restricts expression of toll like receptor 4 (TLR4) target genes in macrophages. H4K20me3 is deposited at the promoters of a subset of these genes by the SMYD5 histone methyltransferase through its association with NCoR co-repressor complexes. Signal-dependent erasure of H4K20me3 is required for effective gene activation and is achieved by NF-KB-dependent delivery of the histone demethylase PHF2. Liver X receptors antagonize TLR4-dependent gene activation by maintaining NCoR/SMYD5-mediated repression. These findings reveal a histone H4K20 tri-methylation/de-methylation strategy that integrates positive and negative signaling inputs that control immunity and homeostasis. mRNA profiling from thioglycollate-elicited mouse macrophages treated with siRNA for Control, Smyd5 and Phf2 for 48 hours followed by 4 hours of LPS treatment.
Project description:Bivalent chromatin domains consisting of the activating histone 3 lysine 4 trimethylation (H3K4me3) and repressive histone 3 lysine 27 trimethylation (H3K27me3) histone modifications are enriched at developmental genes that are repressed in embryonic stem cells but active during differentiation. However, it is unknown whether another repressive histone modification, histone 4 lysine 20 trimethylation (H4K20me3), co-localizes with activating histone marks in ES cells. Here, we describe the previously uncharacterized coupling of the repressive H4K20me3 heterochromatin mark with the activating histone modifications H3K4me3 and histone 3 lysine 36 trimethylation (H3K36me3), and transcriptional machinery (RNA polymerase II; RNAPII), in ES cells. These newly described bivalent domains consisting of H3K4me3/H4K20me3 are predominantly located in intergenic regions and near transcriptional start sites of active genes, while H3K36me3/H4K20me3 are located in intergenic regions and within gene body regions of active genes. Global sequential ChIP, also termed reChIP-Seq, confirmed the simultaneous presence of H3K4me3 and H4K20me3 at the same genomic regions in ES cells. Genes containing H3K4me3/H4K20me3 exhibit decreased RNAPII pausing and are poised for deactivation of RNAPII binding during differentiation relative to H3K4me3 marked genes. An evaluation of transcription factor (TF) binding motif enrichment revealed that DNA sequence may play a role in shaping the landscape of these novel bivalent domains. Moreover, H3K4me3/H4K20me3 and H3K36me3/H4K20me3 bound regions are enriched with repetitive LINE and LTR elements.