Dataset Information

The INO80 complex regulates epigenetic inheritance of heterochromatin (RNA-seq)

ABSTRACT: One key aspect of epigenetic inheritance is that chromatin structure can be stably inherited through generations even after removal of the initial signal that establishes such structure. In fission yeast, the RNA interference (RNAi) machinery is critical for the targeting of histone methyltransferase Clr4 to repetitive DNA elements to establish a large domain of heterochromatin marked with histone H3 lysine 9 methylation (H3K9me). Subsequently during DNA replication, the deposition of parental histones containing H3K9me into daughter DNA strands is expected to recruit Clr4 to modify neighboring new histones, resulting in the inheritance of heterochromatin in both daughter cells. However, pericentric heterochromatin cannot be properly inherited in the absence of RNAi, suggesting the existence of mechanisms that counteract chromatin-based inheritance. Here we show that in the absence of certain components of the INO80 chromatin remodeling complex, pericentric heterochromatin can be properly inherited in RNAi mutants. The ability of INO80 to counter heterochromatin inheritance is attributed to one accessory subunit Iec5, which promotes histone turn over at heterochromatin regions, but has little effects on the ability of INO80 in regulating nucleosome positioning at heterochromatin, gene expression, or the DNA damage response. Slow histone turnover preserves parental histones at repeat regions to enhance epigenetic inheritance of heterochromatin not only in RNAi mutants but also in wild type cells. Our analyses identified a separation-of-function mutation of INO80 in regulating histone turnover at heterochromatin and demonstrate the important role of histone turnover in controlling heterochromatin inheritance and maintaining the proper heterochromatin landscape of the genome.

ORGANISM(S): Schizosaccharomyces pombe

PROVIDER: GSE150544 | GEO | 2020/11/18

REPOSITORIES: GEO

ACCESS DATA

Similar Datasets

Project description:Heterochromatic DNA domains play important roles in the regulation of gene expression and maintenance of genome stability by silencing repetitive DNA elements and transposons. In organisms ranging from fission yeast to mammals, heterochromatin assembly at DNA repeats involves the activity of small noncoding RNAs (sRNAs) associated with the RNA interference (RNAi) pathway. Typically, sRNAs, originating from long noncoding RNAs transcribed from DNA repeats, guide Argonaute-containing effector complexes to complementary nascent RNAs to initiate histone H3 lysine 9 di- and tri-methylation (H3K9me2 and H3K9me3, respectively) and heterochromatin formation. H3K9me is in turn required for recruitment of RNAi to chromatin and promotes sRNA generation. However, how heterochromatin formation, which silences transcription, can proceed by a co-transcriptional mechanism that also promotes sRNA generation remains paradoxical. Here, using Clr4, the fission yeast homolog of mammalian SUV39H H3K9 methyltransferases, we designed active site mutations, which allow H3K9me2 catalysis but block the transition to H3K9me3. We show that H3K9me2 defines a functionally distinct heterochromatin state that is sufficient for RNAi-dependent co-transcriptional gene silencing (CTGS). Unlike H3K9me3 domains, which are transcriptionally silent, H3K9me2 domains are transcriptionally active, contain modifications associated with euchromatic transcription, and couple RNAi-mediated transcript degradation to the establishment of H3K9me domains. The two H3K9me states recruit reader proteins with different efficiencies, explaining their different downstream silencing functions. Furthermore, transition from H3K9me2 to H3K9me3 is required for RNAi-independent epigenetic inheritance of H3K9me domains. Our findings demonstrate that H3K9me2 and H3K9me3 define functionally distinct heterochromatin states and uncover a mechanism for formation of transcriptionally permissive heterochromatin that is compatible with its broadly conserved role in RNAi-mediated genome defense.

Dataset Information

The INO80 complex regulates epigenetic inheritance of heterochromatin (RNA-seq)

Similar Datasets

OmicsDI is part of the ELIXIR infrastructure