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Tatsuya Hirano - One of the best experts on this subject based on the ideXlab platform.
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Condensin based chromosome organization from bacteria to vertebrates
Cell, 2016Co-Authors: Tatsuya HiranoAbstract:Condensins are large protein complexes that play a central role in chromosome organization and segregation in the three domains of life. They display highly characteristic, rod-shaped structures with SMC (structural maintenance of chromosomes) ATPases as their core subunits and organize large-scale chromosome structure through active mechanisms. Most eukaryotic species have two distinct Condensin complexes whose balanced usage is adapted flexibly to different organisms and cell types. Studies of bacterial Condensins provide deep insights into the fundamental mechanisms of chromosome segregation. This Review surveys both conserved features and rich variations of Condensin-based chromosome organization and discusses their evolutionary implications.
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balancing acts of two heat subunits of Condensin i support dynamic assembly of chromosome axes
The Japanese Biochemical Society The Molecular Biology Society of Japan, 2015Co-Authors: Kazuhisa Kinoshita, Tetsuya J Kobayashi, Tatsuya HiranoAbstract:Summary Condensin I is a five-subunit protein complex that plays a central role in mitotic chromosome assembly and segregation in eukaryotes. To dissect its mechanism of action, we reconstituted wild-type and mutant complexes from recombinant subunits and tested their abilities to assemble chromosomes in Xenopus egg cell-free extracts depleted of endogenous Condensins. We find that ATP binding and hydrolysis by SMC subunits have distinct contributions to the action of Condensin I and that continuous ATP hydrolysis is required for structural maintenance of chromosomes. Mutant complexes lacking either one of two HEAT subunits produce abnormal chromosomes with highly characteristic defects and have contrasting structural effects on chromosome axes preassembled with the wild-type complex. We propose that balancing acts of the two HEAT subunits support dynamic assembly of chromosome axes under the control of the SMC ATPase cycle, thereby governing construction of rod-shaped chromosomes in eukaryotic cells.
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Condensin targets and reduces unwound dna structures associated with transcription in mitotic chromosome condensation
Nature Communications, 2015Co-Authors: Takashi Sutani, Tatsuya Hirano, Daisuke Yamashita, Toyonori Sakata, Ryuichiro Nakato, Koji Masuda, Mai Ishibashi, Yutaka Suzuki, Masashige Bando, Katsuhiko ShirahigeAbstract:Chromosome condensation is a hallmark of mitosis in eukaryotes and is a prerequisite for faithful segregation of genetic material to daughter cells. Here we show that Condensin, which is essential for assembling condensed chromosomes, helps to preclude the detrimental effects of gene transcription on mitotic condensation. ChIP-seq profiling reveals that the fission yeast Condensin preferentially binds to active protein-coding genes in a transcription-dependent manner during mitosis. Pharmacological and genetic attenuation of transcription largely rescue bulk chromosome segregation defects observed in Condensin mutants. We also demonstrate that Condensin is associated with and reduces unwound DNA segments generated by transcription, providing a direct link between an in vitro activity of Condensin and its in vivo function. The human Condensin isoform Condensin I also binds to unwound DNA regions at the transcription start sites of active genes, implying that our findings uncover a fundamental feature of Condensin complexes.
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Condensin ii initiates sister chromatid resolution during s phase
Journal of Cell Biology, 2013Co-Authors: Daisuke Yamashita, Tatsuya HiranoAbstract:Condensins I and II are multisubunit complexes that play essential yet distinct functions in chromosome condensation and segregation in mitosis. Unlike Condensin I, Condensin II localizes to the nucleus during interphase, but it remains poorly understood what functions Condensin II might have before mitotic entry. Here, we report that Condensin II changes its chromatin-binding property during S phase. Remarkably, advanced premature chromosome condensation (PCC) assays enabled us to visualize Condensin II forming “sister axes” in replicated regions of chromosomes in S phase cells. Depletion of Condensin II compromised PCC-driven sister chromatid resolution during S phase. Moreover, fluorescence in situ hybridization assays revealed that Condensin II, but not Condensin I, promotes disjoining duplicated chromosomal loci during S phase. Application of mild replicative stress partially impaired this process and further exacerbated phenotypes arising from Condensin II depletion. Our results suggest that Condensin II initiates structural reorganization of duplicated chromosomes during S phase to prepare for their proper condensation and segregation in mitosis.
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Condensins universal organizers of chromosomes with diverse functions
Genes & Development, 2012Co-Authors: Tatsuya HiranoAbstract:Condensins are multisubunit protein complexes that play a fundamental role in the structural and functional organization of chromosomes in the three domains of life. Most eukaryotic species have two different types of Condensin complexes, known as Condensins I and II, that fulfill nonoverlapping functions and are subjected to differential regulation during mitosis and meiosis. Recent studies revealed that the two complexes contribute to a wide variety of interphase chromosome functions, such as gene regulation, recombination, and repair. Also emerging are their cell type- and tissue-specific functions and relevance to human disease. Biochemical and structural analyses of eukaryotic and bacterial Condensins steadily uncover the mechanisms of action of this class of highly sophisticated molecular machines. Future studies on Condensins will not only enhance our understanding of chromosome architecture and dynamics, but also help address a previously underappreciated yet profound set of questions in chromosome biology.
Mitsuhiro Yanagida - One of the best experts on this subject based on the ideXlab platform.
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Suppressor screening reveals common kleisin–hinge interaction in Condensin and cohesin, but different modes of regulation
National Academy of Sciences, 2019Co-Authors: Mitsuhiro YanagidaAbstract:Cohesin and Condensin play fundamental roles in sister chromatid cohesion and chromosome segregation, respectively. Both consist of heterodimeric structural maintenance of chromosomes (SMC) subunits, which possess a head (containing ATPase) and a hinge, intervened by long coiled coils. Non-SMC subunits (Cnd1, Cnd2, and Cnd3 for Condensin; Rad21, Psc3, and Mis4 for cohesin) bind to the SMC heads. Here, we report a large number of spontaneous extragenic suppressors for fission yeast Condensin and cohesin mutants, and their sites were determined by whole-genome sequencing. Mutants of Condensin\u27s non-SMC subunits were rescued by impairing the SUMOylation pathway. Indeed, SUMOylation of Cnd2, Cnd3, and Cut3 occurs in midmitosis, and Cnd3 K870 SUMOylation functionally opposes Cnd subunits. In contrast, cohesin mutants rad21 and psc3 were rescued by loss of the RNA elimination pathway (Erh1, Mmi1, and Red1), and loader mutant mis4 was rescued by loss of Hrp1-mediated chromatin remodeling. In addition, distinct regulations were discovered for Condensin and cohesin hinge mutants. Mutations in the N-terminal helix bundle [containing a helix-turn-helix (HTH) motif] of kleisin subunits (Cnd2 and Rad21) rescue virtually identical hinge interface mutations in cohesin and Condensin, respectively. These mutations may regulate kleisin\u27s interaction with the coiled coil at the SMC head, thereby revealing a common, but previously unknown, suppression mechanism between the hinge and the kleisin N domain, which is required for successful chromosome segregation. We propose that in both Condensin and cohesin, the head (or kleisin) and hinge may interact and collaboratively regulate the resulting coiled coils to hold and release chromosomal DNAs
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Condensin locates at transcriptional termination sites in mitosis, possibly releasing mitotic transcripts
'The Royal Society', 2019Co-Authors: Norihiko Nakazawa, Orie Arakawa, Mitsuhiro YanagidaAbstract:Condensin is an essential component of chromosome dynamics, including mitotic chromosome condensation and segregation, DNA repair, and development. Genome-wide localization of Condensin is known to correlate with transcriptional activity. The functional relationship between Condensin accumulation and transcription sites remains unclear, however. By constructing the auxin-inducible degron strain of Condensin, herein we demonstrate that Condensin does not affect transcription itself. Instead, RNA-processing at transcriptional termination appears to define Condensin accumulation sites during mitosis, in the fission yeast Schizosaccharomyces pombe. Combining the auxin-degron strain with the nda3 β-tubulin cold-sensitive (cs) mutant enabled us to inactivate Condensin in mitotically arrested cells, without releasing the cells into anaphase. Transcriptional activation and termination were not affected by Condensin\u27s degron-mediated depletion, at heat-shock inducible genes or mitotically activated genes. On the other hand, Condensin accumulation sites shifted approximately 500 bp downstream in the auxin-degron of 5′-3′ exoribonuclease Dhp1, in which transcripts became aberrantly elongated, suggesting that Condensin accumulates at transcriptionally terminated DNA regions. Growth defects in mutant strains of 3′-processing ribonuclease and polyA cleavage factors were additive in Condensin temperature-sensitive (ts) mutants. Considering Condensin\u27s in vitro activity to form double-stranded DNAs from unwound, single-stranded DNAs or DNA-RNA hybrids, Condensin-mediated processing of mitotic transcripts at the 3′-end may be a prerequisite for faithful chromosome segregation
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Condensin phosphorylated by the aurora b like kinase ark1 is continuously required until telophase in a mode distinct from top2
Journal of Cell Science, 2011Co-Authors: Norihiko Nakazawa, Rajesh Mehrotra, Masahiro Ebe, Mitsuhiro YanagidaAbstract:Condensin is a conserved protein complex that functions in chromosome condensation and segregation. It has not been previously unequivocally determined whether Condensin is required throughout mitosis. Here, we examined whether Schizosaccharomyces pombe Condensin continuously acts on chromosomes during mitosis and compared its role with that of DNA topoisomerase II (Top2). Using double mutants containing a temperature-sensitive allele of the Condensin SMC2 subunit cut14 (cut14-208) or of top2, together with the cold-sensitive nda3-KM311 mutation (in β-tubulin), temperature-shift experiments were performed. These experiments allowed inactivation of Condensin or Top2 at various stages throughout mitosis, even after late anaphase. The results established that mitotic chromosomes require Condensin and Top2 throughout mitosis, even in telophase. We then showed that the Cnd2 subunit of Condensin (also known as Barren) is the target subunit of Aurora-B-like kinase Ark1 and that Ark1-mediated phosphorylation of Cnd2 occurred throughout mitosis. The phosphorylation sites in Cnd2 were determined by mass spectrometry, and alanine and glutamate residue replacement mutant constructs for these sites were constructed. Alanine substitution mutants of Cnd2, which mimic the unphosphorylated protein, exhibited broad mitotic defects, including at telophase, and overexpression of these constructs caused a severe dominant-negative effect. By contrast, glutamate substitution mutants, which mimic the phosphorylated protein, alleviated the segregation defect in Ark1-inhibited cells. In telophase, the Condensin subunits in cut14-208 mutant accumulated in lumps that contained telomeric DNA and proteins that failed to segregate. Condensin might thus serve to keep the segregated chromosomes apart during telophase.
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Condensin but not cohesin SMC heterodimer induces DNA reannealing through protein-protein assembly.
The EMBO journal, 2003Co-Authors: Akiko Sakai, Kohji Hizume, Takashi Sutani, Kunio Takeyasu, Mitsuhiro YanagidaAbstract:Condensin and cohesin are chromosomal protein complexes required for chromosome condensation and sister chromatid cohesion, respectively. They commonly contain the SMC (structural maintenance of chromosomes) subunits consisting of a long coiled-coil with the terminal globular domains and the central hinge. Condensin and cohesin holo-complexes contain three and two non-SMC subunits, respectively. In this study, DNA interaction with cohesin and Condensin complexes purified from fission yeast was investigated. The DNA reannealing activity is strong for Condensin SMC heterodimer but weak for holo-Condensin, whereas no annealing activity is found for cohesin heterodimer SMC and Rad21-bound heterotrimer complexes. One set of globular domains of the same Condensin SMC is essential for the DNA reannealing activity. In addition, the coiled-coil and hinge region of another SMC are needed. Atomic force microscopy discloses the molecular events of DNA reannealing. SMC assembly that occurs on reannealing DNA seems to be a necessary intermediary step. SMC is eliminated from the completed double-stranded DNA. The ability of heterodimeric SMC to reanneal DNA may be regulated in vivo possibly through the non-SMC heterotrimeric complex.
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Condensin architecture and interaction with dna regulatory non smc subunits bind to the head of smc heterodimer
Current Biology, 2002Co-Authors: Shige H Yoshimura, Kohji Hizume, Takashi Sutani, Kunio Takeyasu, Akiko Murakami, Mitsuhiro YanagidaAbstract:Condensin and cohesin are two protein complexes that act as the central mediators of chromosome condensation and sister chromatid cohesion, respectively. The basic underlying mechanism of action of these complexes remained enigmatic. Direct visualization of Condensin and cohesin was expected to provide hints to their mechanisms. They are composed of heterodimers of distinct structural maintenance of chromosome (SMC) proteins and other non-SMC subunits. Here, we report the first observation of the architecture of Condensin and its interaction with DNA by atomic force microscopy (AFM). The purified Condensin SMC heterodimer shows a head-tail structure with a single head composed of globular domains and a tail with the coiled-coil region. Unexpectedly, the Condensin non-SMC trimers associate with the head of SMC heterodimers, producing a larger head with the tail. The heteropentamer is bound to DNA in a distributive fashion, whereas Condensin SMC heterodimers interact with DNA as aggregates within a large DNA-protein assembly. Thus, non-SMC trimers may regulate the ATPase activity of Condensin by directly interacting with the globular domains of SMC heterodimer and alter the mode of DNA interaction. A model for the action of heteropentamer is presented.
William C. Earnshaw - One of the best experts on this subject based on the ideXlab platform.
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Rapid degradation and 3D CLEM of Condensin reveal chromatin compaction uncoupled from chromosome architecture in mitosis
2017Co-Authors: Kumiko Samejima, Hiromi Ogawa, Daniel G. Booth, James R. Paulson, Linfeng Xie, Cara A. Watson, Melpomeni Platani, Masato T. Kanemaki, William C. EarnshawAbstract:The requirement for Condensin in chromosome formation in somatic cells remains unclear as imperfectly condensed chromosomes do form in conventional Condensin-depleted cells. Here we have dissected the role of Condensin at different stages of vertebrate mitosis by combining auxin-mediated rapid depletion of Condensin subunit SMC2 with chemical genetics to obtain near-synchronous mitotic entry of chicken DT40 cells. We analysed the outcomes by live and fixed-cell microscopy methods, including 3D correlative light and serial block face scanning electron microscopy. Following rapid depletion of Condensin, chromosomal defects were obvious. The chromatin was compacted normally, but formed a single mass of mitotic chromosomes clustered at one side of a bent mitotic spindle. Cultures arrest at prometaphase, eventually exiting mitosis without segregating chromosomes. Experiments titrating the auxin concentration suggest a previously unsuspected dual role of Condensin, as different Condensin levels are required for anaphase chromosome segregation and formation of a normal chromosome architecture.
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Condensin regulates the stiffness of vertebrate centromeres
Molecular Biology of the Cell, 2009Co-Authors: Susana A. Ribeiro, Damien F. Hudson, Christine J. Farr, Jesse C Gatlin, Yimin Dong, Ajit P Joglekar, Lisa A Cameron, Bruce F Mcewen, E D Salmon, William C. EarnshawAbstract:When chromosomes are aligned and bioriented at metaphase, the elastic stretch of centromeric chromatin opposes pulling forces exerted on sister kinetochores by the mitotic spindle. Here we show that Condensin ATPase activity is an important regulator of centromere stiffness and function. Condensin depletion decreases the stiffness of centromeric chromatin by 50% when pulling forces are applied to kinetochores. However, Condensin is dispensable for the normal level of compaction (rest length) of centromeres, which probably depends on other factors that control higher-order chromatin folding. Kinetochores also do not require Condensin for their structure or motility. Loss of stiffness caused by Condensin-depletion produces abnormal uncoordinated sister kinetochore movements, leads to an increase in Mad2(+) kinetochores near the metaphase plate and delays anaphase onset.
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Condensin architect of mitotic chromosomes
Chromosome Research, 2009Co-Authors: Damien F. Hudson, Kathryn M Marshall, William C. EarnshawAbstract:Condensin is a highly conserved pentameric complex consisting of two structural maintenance of chromosome (SMC) ATPase subunits and three auxiliary components. While initially regarded as a key driver of mitotic chromosome condensation, Condensin is increasingly viewed as having a more subtle influence on chromosome architecture. The two Condensin complexes are required to direct the correct folding and organization of chromosomes prior to anaphase and for keeping the chromosomes compact as they separate to the poles. This ancient complex is essential in mitosis and meiosis and has additional roles in gene regulation and DNA repair. The wide variety of biochemical and genetic tools available are gradually unravelling the numerous roles Condensin plays during the cell cycle and shedding light on its mechanism of action.
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Condensin and Repo-Man-PP1 co-operate in the regulation of chromosome architecture during mitosis.
Nature Cell Biology, 2006Co-Authors: Paola Vagnarelli, Damien F. Hudson, Susana A. Ribeiro, Laura Trinkle-mulcahy, Jennifer M. Spence, Fan Lai, Christine J. Farr, Angus I. Lamond, William C. EarnshawAbstract:The reversible condensation of chromosomes during cell division remains a classic problem in cell biology. Condensation requires the Condensin complex in certain experimental systems, but not in many others. Anaphase chromosome segregation almost always fails in Condensin-depleted cells, leading to the formation of prominent chromatin bridges and cytokinesis failure. Here, live-cell analysis of chicken DT40 cells bearing a conditional knockout of Condensin subunit SMC2 revealed that Condensin-depleted chromosomes abruptly lose their compact architecture during anaphase and form massive chromatin bridges. The compact chromosome structure can be preserved and anaphase chromosome segregation rescued by preventing the targeting subunit Repo-Man from recruiting protein phosphatase 1 (PP1) to chromatin at anaphase onset. This study identifies an activity critical for mitotic chromosome structure that is inactivated by Repo-Man-PP1 during anaphase. This activity, provisionally termed 'regulator of chromosome architecture' (RCA), cooperates with Condensin to preserve the characteristic chromosome architecture during mitosis.
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Condensin i interacts with the parp 1 xrcc1 complex and functions in dna single strand break repair
Molecular Cell, 2006Co-Authors: Jason T Heale, Damien F. Hudson, William C. Earnshaw, Alexander R Ball, John A Schmiesing, Jongsoo Kim, Xiangduo Kong, Sharleen Zhou, Kyoko YokomoriAbstract:Summary Condensins are essential protein complexes critical for mitotic chromosome organization. Little is known about the function of Condensins during interphase, particularly in mammalian cells. Here we report the interphase-specific interaction between Condensin I and the DNA nick-sensor poly(ADP-ribose) polymerase 1 (PARP-1). We show that the association between Condensin I, PARP-1, and the base excision repair (BER) factor XRCC1 increases dramatically upon single-strand break damage (SSB) induction. Damage-specific association of Condensin I with the BER factors flap endonuclease 1 (FEN-1) and DNA polymerase δ/ɛ was also observed, suggesting that Condensin I is recruited to interact with BER factors at damage sites. Consistent with this, DNA damage rapidly stimulates the chromatin association of PARP-1, Condensin I, and XRCC1. Furthermore, depletion of Condensin in vivo compromises SSB but not double-strand break (DSB) repair. Our results identify a SSB-specific response of Condensin I through PARP-1 and demonstrate a role for Condensin in SSB repair.
Christian H. Haering - One of the best experts on this subject based on the ideXlab platform.
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The Condensin holocomplex cycles dynamically between open and collapsed states
Nature Structural & Molecular Biology, 2020Co-Authors: Je-kyung Ryu, Christian H. Haering, Allard J. Katan, Eli O. Sluis, Thomas Wisse, Ralph Groot, Cees DekkerAbstract:Atomic force microscopy imaging of yeast Condensin indicates that Condensin may extrude DNA by switching conformation between open O and collapsed B shapes, indicative of a type of scrunching model. Structural maintenance of chromosome (SMC) protein complexes are the key organizers of the spatiotemporal structure of chromosomes. The Condensin SMC complex has recently been shown to be a molecular motor that extrudes large loops of DNA, but the mechanism of this unique motor remains elusive. Using atomic force microscopy, we show that budding yeast Condensin exhibits mainly open ‘O’ shapes and collapsed ‘B’ shapes, and it cycles dynamically between these two states over time, with ATP binding inducing the O to B transition. Condensin binds DNA via its globular domain and also via the hinge domain. We observe a single Condensin complex at the stem of extruded DNA loops, where the neck size of the DNA loop correlates with the width of the Condensin complex. The results are indicative of a type of scrunching model in which Condensin extrudes DNA by a cyclic switching of its conformation between O and B shapes.
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dna loop extruding Condensin complexes can traverse one another
Nature, 2020Co-Authors: Eugene Kim, Christian H. Haering, Jacob W J Kerssemakers, Indra A Shaltiel, Cees DekkerAbstract:Condensin, a key component of the structure maintenance of chromosome (SMC) protein complexes, has recently been shown to be a motor that extrudes loops of DNA1. It remains unclear, however, how Condensin complexes work together to collectively package DNA into chromosomes. Here we use time-lapse single-molecule visualization to study mutual interactions between two DNA-loop-extruding yeast Condensins. We find that these motor proteins, which, individually, extrude DNA in one direction only are able to dynamically change each other’s DNA loop sizes, even when far apart. When they are in close proximity, Condensin complexes are able to traverse each other and form a loop structure, which we term a Z-loop—three double-stranded DNA helices aligned in parallel with one Condensin at each edge. Z-loops can fill gaps left by single loops and can form symmetric dimer motors that pull in DNA from both sides. These findings indicate that Condensin may achieve chromosomal compaction using a variety of looping structures.
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dna loop extruding Condensin complexes can traverse one another
Biophysical Journal, 2020Co-Authors: Eugene Kim, Christian H. Haering, Jacob W J Kerssemakers, Indra A Shaltiel, Cees DekkerAbstract:Condensin, a key member of the Structure Maintenance of Chromosome (SMC) protein complexes, has recently been shown to be a motor that extrudes loops of DNA1. It remains unclear, however, how Condensin complexes work together to collectively package DNA into the chromosomal architecture. Here, we use time-lapse single-molecule visualization to study mutual interactions between two DNA-loop-extruding yeast Condensins. We find that these one-side-pulling motor proteins are able to dynamically change each other’s DNA loop sizes, even when located large distances apart. When coming into close proximity upon forming a loop within a loop, Condensin complexes are, surprisingly, able to traverse each other and form a new type of loop structure, which we term Z loop – three double-stranded DNA helices aligned in parallel with one Condensin at each edge. These Z-loops can fill gaps left by single loops and can form symmetric dimer motors that reel in DNA from both sides. These new findings indicate that Condensin may achieve chromosomal compaction using a variety of looping structures.
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Condensin ii inactivation in interphase does not affect chromatin folding or gene expression
bioRxiv, 2018Co-Authors: Nezar Abdennur, Christian H. Haering, Leonid A Mirny, Wibke Schwarzer, Aleksandra Pekowska, I A Shaltiel, Wolfgang Huber, Francois SpitzAbstract:Condensin complexes have been proposed to play a prominent role in interphase chromatin organization and control of gene expression. Here, we report that the deletion of the central Condensin II kleisin subunit Ncaph2 in differentiated mouse hepatocytes does not lead to significant changes in chromosome organization or in gene expression. Both observations challenge current views that implicate Condensin in interphase chromosomal domain formation and in enhancer-promoter interactions. Instead, we suggest that the previously reported effects of Condensin perturbation may result from their structural role during mitosis, which might indirectly impact the re-establishment of interphase chromosomal architecture after cell division.
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Condensin controls cellular rna levels through the accurate segregation of chromosomes instead of directly regulating transcription
bioRxiv, 2018Co-Authors: Clemence Hocquet, Xavier Robellet, Laurent Modolo, Ximing Sun, Claire Burny, Sara Cuylenhaering, Esther Toselli, Sandra Claudermunster, Lars M Steinmetz, Christian H. HaeringAbstract:Condensins are genome organisers that shape chromosomes and promote their accurate transmission. Several studies have also implicated Condensins in gene expression, although the mechanisms have remained enigmatic. Here, we report on the role of Condensin in gene expression in fission and budding yeasts. In contrast to previous studies, we provide compelling evidence that Condensin plays no direct role in the maintenance of the transcriptome, neither during interphase nor during mitosis. We further show that the changes in gene expression in post-mitotic fission yeast cells that result from Condensin inactivation are largely a consequence of chromosome missegregation during anaphase, which notably depletes the RNA-exosome from daughter cells. Crucially, preventing karyotype abnormalities in daughter cells restores a normal transcriptome despite Condensin inactivation. Thus, chromosome instability, rather than a direct role of Condensin in the transcription process, changes gene expression. This knowledge challenges the concept of gene regulation by canonical Condensin complexes.
Damien F. Hudson - One of the best experts on this subject based on the ideXlab platform.
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mitotic chromosomes are compacted laterally by kif4 and Condensin and axially by topoisomerase iiα
Journal of Cell Biology, 2012Co-Authors: Kumiko Samejima, Paola Vagnarelli, Itaru Samejima, Hiromi Ogawa, Giulia Vargiu, David A Kelly, Flavia De Lima Alves, Alastair R W Kerr, Lydia C Green, Damien F. HudsonAbstract:Mitotic chromosome formation involves a relatively minor condensation of the chromatin volume coupled with a dramatic reorganization into the characteristic “X” shape. Here we report results of a detailed morphological analysis, which revealed that chromokinesin KIF4 cooperated in a parallel pathway with Condensin complexes to promote the lateral compaction of chromatid arms. In this analysis, KIF4 and Condensin were mutually dependent for their dynamic localization on the chromatid axes. Depletion of either caused sister chromatids to expand and compromised the “intrinsic structure” of the chromosomes (defined in an in vitro assay), with loss of Condensin showing stronger effects. Simultaneous depletion of KIF4 and Condensin caused complete loss of chromosome morphology. In these experiments, topoisomerase IIα contributed to shaping mitotic chromosomes by promoting the shortening of the chromatid axes and apparently acting in opposition to the actions of KIF4 and Condensins. These three proteins are major determinants in shaping the characteristic mitotic chromosome morphology.
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Condensin regulates the stiffness of vertebrate centromeres
Molecular Biology of the Cell, 2009Co-Authors: Susana A. Ribeiro, Damien F. Hudson, Christine J. Farr, Jesse C Gatlin, Yimin Dong, Ajit P Joglekar, Lisa A Cameron, Bruce F Mcewen, E D Salmon, William C. EarnshawAbstract:When chromosomes are aligned and bioriented at metaphase, the elastic stretch of centromeric chromatin opposes pulling forces exerted on sister kinetochores by the mitotic spindle. Here we show that Condensin ATPase activity is an important regulator of centromere stiffness and function. Condensin depletion decreases the stiffness of centromeric chromatin by 50% when pulling forces are applied to kinetochores. However, Condensin is dispensable for the normal level of compaction (rest length) of centromeres, which probably depends on other factors that control higher-order chromatin folding. Kinetochores also do not require Condensin for their structure or motility. Loss of stiffness caused by Condensin-depletion produces abnormal uncoordinated sister kinetochore movements, leads to an increase in Mad2(+) kinetochores near the metaphase plate and delays anaphase onset.
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Condensin architect of mitotic chromosomes
Chromosome Research, 2009Co-Authors: Damien F. Hudson, Kathryn M Marshall, William C. EarnshawAbstract:Condensin is a highly conserved pentameric complex consisting of two structural maintenance of chromosome (SMC) ATPase subunits and three auxiliary components. While initially regarded as a key driver of mitotic chromosome condensation, Condensin is increasingly viewed as having a more subtle influence on chromosome architecture. The two Condensin complexes are required to direct the correct folding and organization of chromosomes prior to anaphase and for keeping the chromosomes compact as they separate to the poles. This ancient complex is essential in mitosis and meiosis and has additional roles in gene regulation and DNA repair. The wide variety of biochemical and genetic tools available are gradually unravelling the numerous roles Condensin plays during the cell cycle and shedding light on its mechanism of action.
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Condensin and Repo-Man-PP1 co-operate in the regulation of chromosome architecture during mitosis.
Nature Cell Biology, 2006Co-Authors: Paola Vagnarelli, Damien F. Hudson, Susana A. Ribeiro, Laura Trinkle-mulcahy, Jennifer M. Spence, Fan Lai, Christine J. Farr, Angus I. Lamond, William C. EarnshawAbstract:The reversible condensation of chromosomes during cell division remains a classic problem in cell biology. Condensation requires the Condensin complex in certain experimental systems, but not in many others. Anaphase chromosome segregation almost always fails in Condensin-depleted cells, leading to the formation of prominent chromatin bridges and cytokinesis failure. Here, live-cell analysis of chicken DT40 cells bearing a conditional knockout of Condensin subunit SMC2 revealed that Condensin-depleted chromosomes abruptly lose their compact architecture during anaphase and form massive chromatin bridges. The compact chromosome structure can be preserved and anaphase chromosome segregation rescued by preventing the targeting subunit Repo-Man from recruiting protein phosphatase 1 (PP1) to chromatin at anaphase onset. This study identifies an activity critical for mitotic chromosome structure that is inactivated by Repo-Man-PP1 during anaphase. This activity, provisionally termed 'regulator of chromosome architecture' (RCA), cooperates with Condensin to preserve the characteristic chromosome architecture during mitosis.
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Condensin i interacts with the parp 1 xrcc1 complex and functions in dna single strand break repair
Molecular Cell, 2006Co-Authors: Jason T Heale, Damien F. Hudson, William C. Earnshaw, Alexander R Ball, John A Schmiesing, Jongsoo Kim, Xiangduo Kong, Sharleen Zhou, Kyoko YokomoriAbstract:Summary Condensins are essential protein complexes critical for mitotic chromosome organization. Little is known about the function of Condensins during interphase, particularly in mammalian cells. Here we report the interphase-specific interaction between Condensin I and the DNA nick-sensor poly(ADP-ribose) polymerase 1 (PARP-1). We show that the association between Condensin I, PARP-1, and the base excision repair (BER) factor XRCC1 increases dramatically upon single-strand break damage (SSB) induction. Damage-specific association of Condensin I with the BER factors flap endonuclease 1 (FEN-1) and DNA polymerase δ/ɛ was also observed, suggesting that Condensin I is recruited to interact with BER factors at damage sites. Consistent with this, DNA damage rapidly stimulates the chromatin association of PARP-1, Condensin I, and XRCC1. Furthermore, depletion of Condensin in vivo compromises SSB but not double-strand break (DSB) repair. Our results identify a SSB-specific response of Condensin I through PARP-1 and demonstrate a role for Condensin in SSB repair.