scholarly journals SUV39 SET domains mediate crosstalk of heterochromatic histone marks

2020 ◽  
Author(s):  
Alessandro Stirpe ◽  
Nora Guidotti ◽  
Sarah Northall ◽  
Sinan Kilic ◽  
Alexandre Hainard ◽  
...  
Keyword(s):  
Catalytic Domain ◽  
Constitutive Heterochromatin ◽  
H3k9 Methylation ◽  
Set Domain ◽  
Heterochromatin Formation ◽  
Histone Lysine ◽  
Heterochromatin Silencing ◽  
Central Recruitment ◽  
Genomic Regions ◽  
In Cis

AbstractThe SUV39 class of methyltransferase enzymes deposits histone lysine 9 di- and trimethylation (H3K9me2/3), the epigenetic hallmark of constitutive heterochromatin, which serves as the central recruitment platform for the heterochromatic silencing machinery. How these enzymes are regulated to mark specific genomic regions as heterochromatic is not well understood. Clr4 is the sole H3K9me2/3 methyltransferase in the fission yeast S.pombe and recent evidence suggests that ubiquitination of lysine 14 on H3 tail (H3K14) plays a key role in H3K9 methylation. However, the molecular mechanism of this regulation and its role in heterochromatin formation remains to be determined. Here we present a structure-function approach to understanding how the H3K14ub mark stimulates Clr4 activity in cis. These results show that the H3K14ub substrate binds specifically and tightly to the catalytic domain of Clr4, and thereby activates the enzyme by 250-fold. Mutations that disrupt this mechanism lead to a loss of H3K9me2/3 and abolish heterochromatin silencing similar to a clr4 deletion. Our work reveals a sensor for H3K14 ubiquitylation in the SET domain of Clr4, which mediates the licensing of heterochromatin formation by an epigenetic cross-talk. This sensor is also active in the human SUV39H2 enzyme.

scholarly journals SUV39 SET domains mediate crosstalk of heterochromatic histone marks

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Alessandro Stirpe ◽  
Nora Guidotti ◽  
Sarah J Northall ◽  
Sinan Kilic ◽  
Alexandre Hainard ◽  
...  
Keyword(s):  
Structure Function ◽  
Fission Yeast ◽  
Catalytic Domain ◽  
Constitutive Heterochromatin ◽  
Histone H3 ◽  
H3k9 Methylation ◽  
Set Domain ◽  
Heterochromatin Formation ◽  
Heterochromatin Silencing ◽  
Genomic Regions

The SUV39 class of methyltransferase enzymes deposits histone H3 lysine 9 di- and trimethylation (H3K9me2/3), the hallmark of constitutive heterochromatin. How these enzymes are regulated to mark specific genomic regions as heterochromatic is poorly understood. Clr4 is the sole H3K9me2/3 methyltransferase in the fission yeast Schizosaccharomyces pombe, and recent evidence suggests that ubiquitination of lysine 14 on histone H3 (H3K14ub) plays a key role in H3K9 methylation. However, the molecular mechanism of this regulation and its role in heterochromatin formation remain to be determined. Our structure-function approach shows that the H3K14ub substrate binds specifically and tightly to the catalytic domain of Clr4, and thereby stimulates the enzyme by over 250-fold. Mutations that disrupt this mechanism lead to a loss of H3K9me2/3 and abolish heterochromatin silencing similar to clr4 deletion. Comparison with mammalian SET domain proteins suggests that the Clr4 SET domain harbors a conserved sensor for H3K14ub, which mediates licensing of heterochromatin formation.

The histone chaperone FACT facilitates heterochromatin spreading through regulation of histone turnover and H3K9 methylation states

2021 ◽  
Author(s):  
Magdalena Murawska ◽  
R. A. Greenstein ◽  
Tamas Schauer ◽  
Karl C.F. Olsen ◽  
Henry Ng ◽  
...  
Keyword(s):  
Gene Expression ◽  
Histone Chaperone ◽  
Replication Cycle ◽  
H3k9 Methylation ◽  
Spreading Process ◽  
Epigenetic Marks ◽  
Heterochromatin Formation ◽  
Heterochromatin Silencing

Heterochromatin formation requires three distinct steps: nucleation, self-propagation (spreading) along the chromosome, and faithful maintenance after each replication cycle. Impeding any of those steps induces heterochromatin defects and improper gene expression. The essential histone chaperone FACT has been implicated in heterochromatin silencing, however, the mechanisms by which FACT engages in this process remain opaque. Here, we pin-pointed its function to the heterochromatin spreading process. FACT impairment reduces nucleation-distal H3K9me3 and HP1/Swi6 accumulation at subtelomeres and de-represses genes in the vicinity of heterochromatin boundaries. FACT promotes spreading by repressing heterochromatic histone turnover, which is crucial for the H3K9me2 to me3 transition that enables spreading. FACT mutant spreading defects are suppressed by removal of the H3K9 methylation antagonist Epe1 via nucleosome stabilization. Together, our study identifies FACT as a histone chaperone that specifically promotes heterochromatin spreading and lends support to the model that regulated histone turnover controls the propagation of epigenetic marks.

scholarly journals Abo1 is required for the H3K9me2 to H3K9me3 transition in heterochromatin

2020 ◽  
Vol 10 (1) ◽  
Author(s):  
Wenbo Dong ◽  
Eriko Oya ◽  
Yasaman Zahedi ◽  
Punit Prasad ◽  
J. Peter Svensson ◽  
...  
Keyword(s):  
Constitutive Heterochromatin ◽  
Genomic Stability ◽  
Wild Type ◽  
Key Factors ◽  
Facultative Heterochromatin ◽  
Heterochromatin Formation ◽  
Aaa Atpase ◽  
Genome Wide ◽  
Heterochromatin Silencing

AbstractHeterochromatin regulation is critical for genomic stability. Different H3K9 methylation states have been discovered, with distinct roles in heterochromatin formation and silencing. However, how the transition from H3K9me2 to H3K9me3 is controlled is still unclear. Here, we investigate the role of the conserved bromodomain AAA-ATPase, Abo1, involved in maintaining global nucleosome organisation in fission yeast. We identified several key factors involved in heterochromatin silencing that interact genetically with Abo1: histone deacetylase Clr3, H3K9 methyltransferase Clr4, and HP1 homolog Swi6. Cells lacking Abo1 cultivated at 30 °C exhibit an imbalance of H3K9me2 and H3K9me3 in heterochromatin. In abo1∆ cells, the centromeric constitutive heterochromatin has increased H3K9me2 but decreased H3K9me3 levels compared to wild-type. In contrast, facultative heterochromatin regions exhibit reduced H3K9me2 and H3K9me3 levels in abo1∆. Genome-wide analysis showed that abo1∆ cells have silencing defects in both the centromeres and subtelomeres, but not in a subset of heterochromatin islands in our condition. Thus, our work uncovers a role of Abo1 in stabilising directly or indirectly Clr4 recruitment to allow the H3K9me2 to H3K9me3 transition in heterochromatin.

scholarly journals SETDB1-Mediated Silencing of Retroelements

Viruses ◽  
2020 ◽  
Vol 12 (6) ◽  
pp. 596 ◽  
Author(s):  
Kei Fukuda ◽  
Yoichi Shinkai
Keyword(s):  
Genome Stability ◽  
Histone H3 ◽  
Endogenous Retroviruses ◽  
H3k9 Methylation ◽  
Epigenetic Factors ◽  
Set Domain ◽  
H3k9 Trimethylation ◽  
Histone Lysine ◽  
Histone Lysine Methyltransferase ◽  
Lysine Methyltransferase

SETDB1 (SET domain bifurcated histone lysine methyltransferase 1) is a protein lysine methyltransferase and methylates histone H3 at lysine 9 (H3K9). Among other H3K9 methyltransferases, SETDB1 and SETDB1-mediated H3K9 trimethylation (H3K9me3) play pivotal roles for silencing of endogenous and exogenous retroelements, thus contributing to genome stability against retroelement transposition. Furthermore, SETDB1 is highly upregulated in various tumor cells. In this article, we describe recent advances about how SETDB1 activity is regulated, how SETDB1 represses various types of retroelements such as L1 and class I, II, and III endogenous retroviruses (ERVs) in concert with other epigenetic factors such as KAP1 and the HUSH complex and how SETDB1-mediated H3K9 methylation can be maintained during replication.

Swi6/HP1 binding to RNA-DNA hybrids initiates heterochromatin assembly

2020 ◽  
Author(s):  
Jagmohan Singh ◽  
Jyotsna Kumar ◽  
Swati Haldar ◽  
Neelima Gupta ◽  
Viney Kumar ◽  
...  
Keyword(s):  
Fission Yeast ◽  
Rnai Pathway ◽  
Affinity Binding ◽  
Heterochromatin Formation ◽  
Independent Mechanism ◽  
Alternate Model ◽  
Self Association ◽  
Heterochromatin Silencing ◽  
Heterochromatin Structure ◽  
Heterochromatin Assembly

Abstract Heterochromatin formation in fission yeast and metazoans involves di/trimethylation of histone H3 at lysine 9 position (me2/me3-K9-H3) by the histone methyltransferase (HMT) Suv39/Clr4, followed by binding of Swi6/HP1 to me2/me3-K9-H3 via its chromodomain1. Subsequent self-association of Swi6/HP1 on adjacent nucleosomes leads to folded heterochromatin structure1-3. An alternate model suggests a concerted participation of Clr4 and Swi6/HP12,3. HP1 binding to RNA has been invoked for heterochromatin silencing in metazoans4,5. Swi6/HP1 also binds and channels RNA to exosome pathway in fission yeast6. Recruitment of Swi6/HP1 to centromere is also dependent on the RNAi pathway7. Here we show that Swi6/HP1 exhibits binding to RNAs, ranging from promiscuous, low-affinity binding to mRNAs, to moderate-affinity binding to the RNAi-generated siRNAs corresponding to the repeats present in heterochromatin regions7, to high affinity binding to the RNA-DNA hybrids cognate to the repeats. Together with sensitivity of Swi6 localization and silencing to RNaseH, our results suggest a dynamic distribution of Swi6/HP1 among the heterochromatin and euchromatic transcripts and binding to RNA-DNA hybrid as an RNAi-dependent and Me2/me3-K9-H3-independent mechanism of recruitment, leading to heterochromatin formation and silencing.

scholarly journals Histone H3K9 methylation promotes formation of genome compartments inCaenorhabditis elegansvia chromosome compaction and perinuclear anchoring

2020 ◽  
Vol 117 (21) ◽  
pp. 11459-11470 ◽  
Author(s):  
Qian Bian ◽  
Erika C. Anderson ◽  
Qiming Yang ◽  
Barbara J. Meyer
Keyword(s):  
Gene Expression ◽  
Nuclear Periphery ◽  
Chromosome Conformation ◽  
C Elegans ◽  
Genome Wide ◽  
Central Regions ◽  
In Trans ◽  
Genomic Regions ◽  
In Cis ◽  
Gene Expression Levels

Genomic regions preferentially associate with regions of similar transcriptional activity, partitioning genomes into active and inactive compartments within the nucleus. Here we explore mechanisms controlling genome compartment organization inCaenorhabditis elegansand investigate roles for compartments in regulating gene expression. Distal arms ofC. eleganschromosomes, which are enriched for heterochromatic histone modifications H3K9me1/me2/me3, interact with each other bothin cisandin trans,while interacting less frequently with central regions, leading to genome compartmentalization. Arms are anchored to the nuclear periphery via the nuclear envelope protein CEC-4, which binds to H3K9me. By performing genome-wide chromosome conformation capture experiments (Hi-C), we showed that eliminating H3K9me1/me2/me3 through mutations in the methyltransferase genesmet-2andset-25significantly impaired formation of inactive Arm and active Center compartments.cec-4mutations also impaired compartmentalization, but to a lesser extent. We found that H3K9me promotes compartmentalization through two distinct mechanisms: Perinuclear anchoring of chromosome arms via CEC-4 to promote theircisassociation, and an anchoring-independent mechanism that compacts individual chromosome arms. In bothmet-2 set-25andcec-4mutants, no dramatic changes in gene expression were found for genes that switched compartments or for genes that remained in their original compartment, suggesting that compartment strength does not dictate gene-expression levels. Furthermore, H3K9me, but not perinuclear anchoring, also contributes to formation of another prominent feature of chromosome organization, megabase-scale topologically associating domains on X established by the dosage compensation condensin complex. Our results demonstrate that H3K9me plays crucial roles in regulating genome organization at multiple levels.

scholarly journals Structure of the Catalytic Domain of Human DOT1L, a Non-SET Domain Nucleosomal Histone Methyltransferase

Cell ◽  
2003 ◽  
Vol 112 (5) ◽  
pp. 711-723 ◽  
Author(s):  
Jinrong Min ◽  
Qin Feng ◽  
Zhizhong Li ◽  
Yi Zhang ◽  
Rui-Ming Xu
Keyword(s):  
Catalytic Domain ◽  
Histone Methyltransferase ◽  
Set Domain ◽  
Nucleosomal Histone

scholarly journals Silencing of Euchromatic Transposable Elements as a Consequence of Nuclear Lamina Dysfunction

Cells ◽  
2020 ◽  
Vol 9 (3) ◽  
pp. 625
Author(s):  
Valeria Cavaliere ◽  
Giovanna Lattanzi ◽  
Davide Andrenacci
Keyword(s):  
Transposable Elements ◽  
Genome Instability ◽  
Nuclear Periphery ◽  
Nuclear Lamina ◽  
Rna Degradation ◽  
Loss Of Function ◽  
Heterochromatin Formation ◽  
Repressive Effect ◽  
Regulatory Effects ◽  
Genomic Regions

Transposable elements (TEs) are mobile genomic sequences that are normally repressed to avoid proliferation and genome instability. Gene silencing mechanisms repress TEs by RNA degradation or heterochromatin formation. Heterochromatin maintenance is therefore important to keep TEs silent. Loss of heterochromatic domains has been linked to lamin mutations, which have also been associated with derepression of TEs. In fact, lamins are structural components of the nuclear lamina (NL), which is considered a pivotal structure in the maintenance of heterochromatin domains at the nuclear periphery in a silent state. Here, we show that a lethal phenotype associated with Lamin loss-of-function mutations is influenced by Drosophila gypsy retrotransposons located in euchromatic regions, suggesting that NL dysfunction has also effects on active TEs located in euchromatic loci. In fact, expression analysis of different long terminal repeat (LTR) retrotransposons and of one non-LTR retrotransposon located near active genes shows that Lamin inactivation determines the silencing of euchromatic TEs. Furthermore, we show that the silencing effect on euchromatic TEs spreads to the neighboring genomic regions, with a repressive effect on nearby genes. We propose that NL dysfunction may have opposed regulatory effects on TEs that depend on their localization in active or repressed regions of the genome.

scholarly journals LSD1 prevents aberrant heterochromatin formation in Neurospora crassa

2020 ◽  
Vol 48 (18) ◽  
pp. 10199-10210
Author(s):  
William K Storck ◽  
Vincent T Bicocca ◽  
Michael R Rountree ◽  
Shinji Honda ◽  
Tereza Ormsby ◽  
...  
Keyword(s):  
Dna Methylation ◽  
Neurospora Crassa ◽  
Constitutive Heterochromatin ◽  
Histone H3 ◽  
Feedback Mechanism ◽  
Histone Demethylase ◽  
Histone Deacetylation ◽  
Heterochromatin Formation ◽  
Lysine Specific Demethylase ◽  
Specialized Form

Abstract Heterochromatin is a specialized form of chromatin that restricts access to DNA and inhibits genetic processes, including transcription and recombination. In Neurospora crassa, constitutive heterochromatin is characterized by trimethylation of lysine 9 on histone H3, hypoacetylation of histones, and DNA methylation. We explored whether the conserved histone demethylase, lysine-specific demethylase 1 (LSD1), regulates heterochromatin in Neurospora, and if so, how. Though LSD1 is implicated in heterochromatin regulation, its function is inconsistent across different systems; orthologs of LSD1 have been shown to either promote or antagonize heterochromatin expansion by removing H3K4me or H3K9me respectively. We identify three members of the Neurospora LSD complex (LSDC): LSD1, PHF1, and BDP-1. Strains deficient for any of these proteins exhibit variable spreading of heterochromatin and establishment of new heterochromatin domains throughout the genome. Although establishment of H3K9me3 is typically independent of DNA methylation in Neurospora, instances of DNA methylation-dependent H3K9me3 have been found outside regions of canonical heterochromatin. Consistent with this, the hyper-H3K9me3 phenotype of Δlsd1 strains is dependent on the presence of DNA methylation, as well as HCHC-mediated histone deacetylation, suggesting that spreading is dependent on some feedback mechanism. Altogether, our results suggest LSD1 works in opposition to HCHC to maintain proper heterochromatin boundaries.

Sign in / Sign up

Export Citation Format

Share Document