Three-dimensional (3D) chromatin structure plays a critical role in development, gene regulation, and cellular identity. Alterations to this structure can have profound effects on cellular phenotypes and have been associated with a variety of diseases including multiple types of cancer. One of several forces that help shape 3D chromatin structure is liquid-liquid phase separation, a form of self-association between biomolecules that can sequester regions of chromatin into subnuclear droplets or even membraneless organelles like nucleoli. This review focuses on a class of oncogenic fusion proteins that appear to exert their oncogenic function via phase-separation-driven alterations to 3D chromatin structure. Here, we review what is known about the mechanisms by which these oncogenic fusion proteins phase separate in the nucleus and their role in shaping the 3D chromatin structure. We discuss the potential for this phenomenon to be a more widespread mechanism of oncogenesis.
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http://dx.doi.org/10.1016/j.gde.2022.101901 | DOI Listing |
Genes Dev
January 2025
Oncode Institute, Hubrecht Institute, Royal Netherlands Academy of Arts and Sciences (KNAW), University Medical Center Utrecht, Utrecht 3584 CT, the Netherlands;
Enhancers are tissue-specific regulatory DNA elements that can activate transcription of genes over distance. Their target genes most often are located in the same contact domain-chromosomal entities formed by cohesin DNA loop extrusion and typically flanked by CTCF-bound boundaries. Enhancers shared by multiple unrelated genes are underexplored but may be more common than anticipated.
View Article and Find Full Text PDFJ Eukaryot Microbiol
January 2025
Laboratory of Cytology of Unicellular Organisms, Institute of Cytology of the Russian Academy of Sciences, St. Petersburg, Russia.
The genus Pelomyxa includes 15 species of anaerobic Archamoebae with remarkable diverse nucleoplasm morphology. Nuclear structures, like chromatin and nucleoli, of several members of the genus was previously identified only based on their ultrastructural similarity to typical structures of somatic cells of higher eukaryotes. Here, we explored an easy-to-use, one-step intravital staining method with DAPI and pyronin to distinguish between DNA and RNA structures in nuclei of unfixed cells of Pelomyxa belevskii and P.
View Article and Find Full Text PDFNucleosome repositioning is essential for establishing nucleosome-depleted regions (NDRs) to initiate transcription. This process has been extensively studied using structural, biochemical, and single-molecule approaches, which require homogenously positioned nucleosomes. This is often achieved using the Widom 601 sequence, a highly efficient nucleosome positioning element (NPE) selected for its unusually strong binding to the H3-H4 histone tetramer.
View Article and Find Full Text PDFGene syntax-the order and arrangement of genes and their regulatory elements-shapes the dynamic coordination of both natural and synthetic gene circuits. Transcription at one locus profoundly impacts the transcription of nearby adjacent genes, but the molecular basis of this effect remains poorly understood. Here, using integrated reporter circuits in human cells, we show that supercoiling-mediated feedback regulates expression of adjacent genes in a syntax-specific manner.
View Article and Find Full Text PDFThe formation of condensed heterochromatin is critical for establishing cell-specific transcriptional programs. To reveal structural transitions underlying heterochromatin formation in maturing mouse rod photoreceptors, we apply cryo-EM tomography, AI-assisted deep denoising, and molecular modeling. We find that chromatin isolated from immature retina cells contains many closely apposed nucleosomes with extremely short or absent nucleosome linkers, which are inconsistent with the typical two-start zigzag chromatin folding.
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