Mitotic chromosomes scale to nucleo-cytoplasmic ratio and cell size in Xenopus
Ontology highlight
ABSTRACT:
ORGANISM(S): Xenopus laevis
PROVIDER: GSE217111 | GEO | 2023/05/02
REPOSITORIES: GEO
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Project description:Mitotic chromosomes scale to nucleo-cytoplasmic ratio and cell size in Xenopus
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Project description:During the rapid and reductive cleavage divisions of early embryogenesis, subcellular structures such as the nucleus and mitotic spindle scale to decreasing cell size. Mitotic chromosomes also decrease in size during development, presumably to scale coordinately with mitotic spindles, but the underlying mechanisms are unclear. Here we combine in vivo and in vitro approaches using eggs and embryos from the frog Xenopus laevis to show that mitotic chromosome scaling is mechanistically distinct from other forms of subcellular scaling. We found that mitotic chromosomes scale continuously with cell, spindle, and nuclear size in vivo. However, unlike for spindles and nuclei, mitotic chromosome size cannot be reset by cytoplasmic factors from earlier developmental stages. In vitro, increasing nuclear-cytoplasmic (N/C) ratio is sufficient to recapitulate mitotic chromosome scaling, but not nuclear or spindle scaling, through differential loading of maternal factors during interphase. An additional pathway involving importin α scales mitotic chromosomes to cell surface area/volume ratio (SA/V) during metaphase. Finally, single-chromosome immunofluorescence and Hi-C data suggest that mitotic chromosomes shrink during embryogenesis through decreased recruitment of condensin I, resulting in major rearrangements of DNA loop architecture to accommodate the same amount of DNA on a shorter chromosome axis. Together, our findings demonstrate how mitotic chromosome size is set by spatially and temporally distinct developmental cues in the early embryo.
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Project description:Selective compartmentalization in condensin-depleted mitotic chromosomes
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Project description:To test if mitotic chromosomes have decreased accessibility, we utilized Assay for Transposase-Accessible Chromatin using sequencing (ATAC-seq) analysis where the integration of sequencing-compatible adaptors by the Tn5 transposase is directly correlated with the accessibility of genomic regions
2016-11-17 | GSE85184 | GEO
Project description:During mitosis, condensin activity is thought to disrupt interphase chromatin structures. Here, we utilize condensin-deficient mitotic chromosomes as a unique architectural platform to further investigate genome folding principles. Upon condensin loss, compartments progressively emerge in mitotic chromosomes. Euchromatin diverges into two different compartments A1 and A2, the former of which shows strong homotypic interactions while the latter exhibit reduced self-aggregation. Constitutive heterochromatin (B1) displays reduced level of compartmentalization and the normally inert facultative heterochromatin (B2) participates to compartmentalize the genome. Dynamically, A1 compartment is established remarkably fast with similarly efficient separation from B1 while reformation of B1 is delayed, implying that A1 self-attraction is the engine to compartmentalizalize the condensin-depleted mitotic chromosomes. Notified by the mitotic compartmentalization of B1 which lacks HP1 binding, we sought to explore the role of HP1 proteins in genome folding and demonstrat that HP1& are dispensible for chromatin structural restoration during cell divison. Our observations unveil delicate patterns and novel principles of genome compartmentalization that are otherwise hidden in interphase cells.
2023-11-22 | GSE229179 | GEO
Project description:During mitosis, condensin activity is thought to disrupt interphase chromatin structures. Here, we utilize condensin-deficient mitotic chromosomes as a unique architectural platform to further investigate genome folding principles. Upon condensin loss, compartments progressively emerge in mitotic chromosomes. Euchromatin diverges into two different compartments A1 and A2, the former of which shows strong homotypic interactions while the latter exhibit reduced self-aggregation. Constitutive heterochromatin (B1) displays reduced level of compartmentalization and the normally inert facultative heterochromatin (B2) participates to compartmentalize the genome. Dynamically, A1 compartment is established remarkably fast with similarly efficient separation from B1 while reformation of B1 is delayed, implying that A1 self-attraction is the engine to compartmentalizalize the condensin-depleted mitotic chromosomes. Notified by the mitotic compartmentalization of B1 which lacks HP1 binding, we sought to explore the role of HP1 proteins in genome folding and demonstrat that HP1& are dispensible for chromatin structural restoration during cell divison. Our observations unveil delicate patterns and novel principles of genome compartmentalization that are otherwise hidden in interphase cells.
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Project description:During mitosis, condensin activity is thought to disrupt interphase chromatin structures. Here, we utilize condensin-deficient mitotic chromosomes as a unique architectural platform to further investigate genome folding principles. Upon condensin loss, compartments progressively emerge in mitotic chromosomes. Euchromatin diverges into two different compartments A1 and A2, the former of which shows strong homotypic interactions while the latter exhibit reduced self-aggregation. Constitutive heterochromatin (B1) displays reduced level of compartmentalization and the normally inert facultative heterochromatin (B2) participates to compartmentalize the genome. Dynamically, A1 compartment is established remarkably fast with similarly efficient separation from B1 while reformation of B1 is delayed, implying that A1 self-attraction is the engine to compartmentalizalize the condensin-depleted mitotic chromosomes. Notified by the mitotic compartmentalization of B1 which lacks HP1 binding, we sought to explore the role of HP1 proteins in genome folding and demonstrat that HP1& are dispensible for chromatin structural restoration during cell divison. Our observations unveil delicate patterns and novel principles of genome compartmentalization that are otherwise hidden in interphase cells.
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Project description:The extreme length of chromosomal DNA requires organizing mechanisms to both promote functional genetic interactions and ensure faithful chromosome segregation when cells divide. Microscopy and genome wide contact frequency (Hi-C) analyses indicate that intra-chromosomal looping of DNA is a primary pathway of chromosomal organization during all stages of the cell cycle (Dekker, J. & Mirny, L. . Cell 164, 1110–1121 (2016). Although the enzymatic pathways required for DNA loop formation are yet to be fully characterized, the activity of the SMC family of proteins has been consistently associated with this process in interphase and mitosis. Here we use Hi-C to study the reorganization of budding yeast chromosome conformation in early mitosis and the role of SMCs in this process. Using polymer simulations, we find that the differences between interphase and mitotic Hi-C maps can be explained by the formation of intra-chromosomal (cis-) loops in mitotic chromosomes. We demonstrate that mitotic SMC cohesin activity is required for formation of cis-loops, independently of sister-chromatid cohesion. In contrast, SMC condensin is not required for loop formation in these early mitotic cells. Rather condensin activity promotes distinct higher order structures in the chromosomes at centromeres and in the rDNA proximal regions. Thus we demonstrate that cohesin-dependent cis-loops provide the primary higher order organization of budding yeast mitotic chromosomes, independently of condensin and sister chromatid cohesion.
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Project description:During mitosis, condensin activity is thought to disrupt interphase chromatin structures. Here, we utilize condensin-deficient mitotic chromosomes as a unique architectural platform to further investigate genome folding principles. Upon condensin loss, compartments progressively emerge in mitotic chromosomes. Euchromatin diverges into two different compartments A1 and A2, the former of which shows strong homotypic interactions while the latter exhibit reduced self-aggregation. Constitutive heterochromatin (B1) displays reduced level of compartmentalization and the normally inert facultative heterochromatin (B2) participates to compartmentalize the genome. Dynamically, A1 compartment is established remarkably fast with similarly efficient separation from B1 while reformation of B1 is delayed, implying that A1 self-attraction is the engine to compartmentalizalize the condensin-depleted mitotic chromosomes. Notified by the mitotic compartmentalization of B1 which lacks HP1 binding, we sought to explore the role of HP1 proteins in genome folding and demonstrat that HP1& are dispensible for chromatin structural restoration during cell divison. Our observations unveil delicate patterns and novel principles of genome compartmentalization that are otherwise hidden in interphase cells.
2023-11-22 | GSE248254 | GEO
Project description:During mitosis, condensin activity is thought to disrupt interphase chromatin structures. Here, we utilize condensin-deficient mitotic chromosomes as a unique architectural platform to further investigate genome folding principles. Upon condensin loss, compartments progressively emerge in mitotic chromosomes. Euchromatin diverges into two different compartments A1 and A2, the former of which shows strong homotypic interactions while the latter exhibit reduced self-aggregation. Constitutive heterochromatin (B1) displays reduced level of compartmentalization and the normally inert facultative heterochromatin (B2) participates to compartmentalize the genome. Dynamically, A1 compartment is established remarkably fast with similarly efficient separation from B1 while reformation of B1 is delayed, implying that A1 self-attraction is the engine to compartmentalizalize the condensin-depleted mitotic chromosomes. Notified by the mitotic compartmentalization of B1 which lacks HP1 binding, we sought to explore the role of HP1 proteins in genome folding and demonstrat that HP1& are dispensible for chromatin structural restoration during cell divison. Our observations unveil delicate patterns and novel principles of genome compartmentalization that are otherwise hidden in interphase cells.
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