Dataset Information

Organization of Chromatin by Intrinsic and Regulated Phase Separation.

ABSTRACT: Eukaryotic chromatin is highly condensed but dynamically accessible to regulation and organized into subdomains. We demonstrate that reconstituted chromatin undergoes histone tail-driven liquid-liquid phase separation (LLPS) in physiologic salt and when microinjected into cell nuclei, producing dense and dynamic droplets. Linker histone H1 and internucleosome linker lengths shared across eukaryotes promote phase separation of chromatin, tune droplet properties, and coordinate to form condensates of consistent density in manners that parallel chromatin behavior in cells. Histone acetylation by p300 antagonizes chromatin phase separation, dissolving droplets in vitro and decreasing droplet formation in nuclei. In the presence of multi-bromodomain proteins, such as BRD4, highly acetylated chromatin forms a new phase-separated state with droplets of distinct physical properties, which can be immiscible with unmodified chromatin droplets, mimicking nuclear chromatin subdomains. Our data suggest a framework, based on intrinsic phase separation of the chromatin polymer, for understanding the organization and regulation of eukaryotic genomes.

SUBMITTER: Gibson BA

PROVIDER: S-EPMC6778041 | biostudies-literature | 2019 Oct

REPOSITORIES: biostudies-literature

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Organization of Chromatin by Intrinsic and Regulated Phase Separation.

Gibson Bryan A BA Doolittle Lynda K LK Schneider Maximillian W G MWG Jensen Liv E LE Gamarra Nathan N Henry Lisa L Gerlich Daniel W DW Redding Sy S Rosen Michael K MK

Cell 20190919 2

Eukaryotic chromatin is highly condensed but dynamically accessible to regulation and organized into subdomains. We demonstrate that reconstituted chromatin undergoes histone tail-driven liquid-liquid phase separation (LLPS) in physiologic salt and when microinjected into cell nuclei, producing dense and dynamic droplets. Linker histone H1 and internucleosome linker lengths shared across eukaryotes promote phase separation of chromatin, tune droplet properties, and coordinate to form condensates ...[more]

PMID: 31543265

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Project description:Development of cancer is intimately associated with genetic abnormalities that target proteins with intrinsically disordered regions (IDRs). In human hematological malignancies, recurrent chromosomal translocation of nucleoporin (NUP98 or NUP214) generates an aberrant chimera that invariably retains nucleoporin’s IDR, tandemly dispersed phenylalanine-andglycine (FG) repeats1-3. However, it remains largely elusive how unstructured IDRs contribute to oncogenesis. We here show that IDR or FG repeats harbored within NUP98-HOXA9, a homeodomain-containing transcription factor (TF) chimera recurrently detected in acute leukemia patients1,4,5, is essential for establishing nuclear liquid-liquid phase separation (LLPS) puncta and for inducing leukemic transformation of primary hematopoietic cells in vitro and in vivo. Strikingly, LLPS of NUP98-HOXA9 not only promotes chromatin occupancy of chimera TF oncoproteins but is also required for formation of a broad, ‘super-enhancer’-like binding pattern, typically seen at a battery of leukemia-related loci exemplified by HOX, MEIS and PBX genes, potentiating their transcriptional activation. An artificial HOX chimera, created by replacing NUP98’s FG repeats with an unrelated LLPSforming IDR of FUS6,7, had similar enhancement effects on chimera’s chromatin binding and target gene activation. Via Hi-C mapping, we further demonstrated that the phase-separated NUP98-HOXA9 protein assembly is able to induce formation of CTCF-independent chromatin looping enriched at leukemic oncogenes. Together, this report describes a proof-of-principle example wherein cancer acquires mutation to establish condensates of oncogenic TFs via a phase separation mechanism, which simultaneously enhances their chromatin targeting and induces organization of aberrant three-dimensional chromatin structure during tumorous transformation. As a range of LLPS-competent molecules are implicated in various human cancers, this mechanism can potentially be generalized to many malignant and diseased settings.

Dataset Information

Organization of Chromatin by Intrinsic and Regulated Phase Separation.

Publications

Organization of Chromatin by Intrinsic and Regulated Phase Separation.

Similar Datasets

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