New insights into cohesin loading

Litwin, Ireneusz; Wysocki, Robert

doi:10.1007/s00294-017-0723-6

Cited by 30 publications

(29 citation statements)

References 98 publications

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“…The formation of sister chromatid cohesion is divided into several steps: cohesin loading, establishment, and maintenance (Litwin and Wysocki 2018). These steps are molecularly distinct and occur in sequential order.…”

Section: Defects In Recombination In the Presence Of A Pcmentioning

confidence: 99%

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A Novel Role for α-Importins and Akirin in Establishment of Meiotic Sister Chromatid Cohesion in Caenorhabditis elegans

et al. 2018

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During meiotic prophase I, sister chromatid cohesion is established in a way that supports the assembly of the synaptonemal complex (SC). The SC connects homologous chromosomes, directing meiotic recombination to create crossovers. In this paper, we identify two proteins that cooperate to import and load meiotic cohesins, thus indirectly promoting SC assembly. AKIR-1 is a protein with a previously identified meiotic role in SC disassembly. akir-1 mutants have no obvious defects in sister chromatid cohesion. We identified ima-2, a gene encoding for an a-importin nuclear transport protein, as a gene interacting with akir-1. Analysis of akir-1;ima-2 double mutants reveals a decrease in the number of germline nuclei and the formation of polycomplexes (PCs) (an SC protein aggregate). These PCs contain proteins that are part of the two main substructures of the SC: the central region and the lateral element. Unlike typical PCs, they also contain sister chromatid cohesion proteins. In akir-1;ima-2 double mutants, PCs are located in both the nucleus and the cytoplasm. This suggests that the defects observed in the double mutants are both in nuclear import and in the assembly of sister chromatid cohesion. PC formation is also associated with recombination defects leading to reduced numbers of crossovers. Similarly to cohesion mutants, the pairing center protein HIM-8 is mislocalized in akir-1;ima-2 double mutants, forming multiple foci. We propose that AKIR-1 and IMA-2 operate in parallel pathways to import and load chromosomally associated cohesin complex proteins in meiotic nuclei, a novel finding for both of these conserved proteins.

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Section: Defects In Recombination In the Presence Of A Pcmentioning

confidence: 99%

“…In some organisms, other cohesion subunits are replaced as well. Cohesin loading is a regulated stepwise process that requires the cohesion loaders Scc2 and Scc4, and proteins involved in cohesion establishment such as Eco1 [reviewed in Litwin and Wysocki (2018) and Reichman et al (2018)].…”

mentioning

confidence: 99%

A Novel Role for α-Importins and Akirin in Establishment of Meiotic Sister Chromatid Cohesion in Caenorhabditis elegans

et al. 2018

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“…Cohesin is loaded onto chromosomes in the G1 phase of the cell cycle to establish sister chromatids cohesion during replication [ 98 , 115 , 116 ]. In prophase, cohesin is removed from chromosome arms, but it is retained at the centromeric region until the anaphase onset, giving rise to the classical, X-shaped mitotic chromosomes morphology [ 115 , 117 ].…”

Section: Regulation Of Topoisomerase II Activity: Guidance By the mentioning

confidence: 99%

A Topology-Centric View on Mitotic Chromosome Architecture

Piskadlo

Oliveira

2017

IJMS

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Mitotic chromosomes are long-known structures, but their internal organization and the exact process by which they are assembled are still a great mystery in biology. Topoisomerase II is crucial for various aspects of mitotic chromosome organization. The unique ability of this enzyme to untangle topologically intertwined DNA molecules (catenations) is of utmost importance for the resolution of sister chromatid intertwines. Although still controversial, topoisomerase II has also been proposed to directly contribute to chromosome compaction, possibly by promoting chromosome self-entanglements. These two functions raise a strong directionality issue towards topoisomerase II reactions that are able to disentangle sister DNA molecules (in trans) while compacting the same DNA molecule (in cis). Here, we review the current knowledge on topoisomerase II role specifically during mitosis, and the mechanisms that directly or indirectly regulate its activity to ensure faithful chromosome segregation. In particular, we discuss how the activity or directionality of this enzyme could be regulated by the SMC (structural maintenance of chromosomes) complexes, predominantly cohesin and condensin, throughout mitosis.

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“…In S. cerevisiae, the core cohesin complex consists of Smc1, Smc3, Scc3 and an α-kleisin (Scc1 and Rec8 in mitosis and meiosis respectively) [4]. Smc1 interacts with Smc3 via their hinge domains, and their ATPase head domains are linked by the kleisin subunit [5]. Scc3 is able to interact with the kleisin subunit [6].…”

Section: Introductionmentioning

confidence: 99%

The cohesin loader SCC2 contains a PHD finger that is required for meiosis in land plants

Wang

Sun

et al. 2020

PLoS Genet

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Cohesin, a multisubunit protein complex, is required for holding sister chromatids together during mitosis and meiosis. The recruitment of cohesin by the sister chromatid cohesion 2/4 (SCC2/4) complex has been extensively studied in Saccharomyces cerevisiae mitosis, but its role in mitosis and meiosis remains poorly understood in multicellular organisms, because complete loss-of-function of either gene causes embryonic lethality. Here, we identified a weak allele of Atscc2 (Atscc2-5) that has only minor defects in vegetative development but exhibits a significant reduction in fertility. Cytological analyses of Atscc2-5 reveal multiple meiotic phenotypes including defects in chromosomal axis formation, meiosis-specific cohesin loading, homolog pairing and synapsis, and AtSPO11-1-dependent double strand break repair. Surprisingly, even though AtSCC2 interacts with AtSCC4 in vitro and in vivo, meiosis-specific knockdown of AtSCC4 expression does not cause any meiotic defect, suggesting that the SCC2-SCC4 complex has divergent roles in mitosis and meiosis. SCC2 homologs from land plants have a unique plant homeodomain (PHD) motif not found in other species. We show that the AtSCC2 PHD domain can bind to the N terminus of histones and is required for meiosis but not mitosis. Taken together, our results provide evidence that unlike SCC2 in other organisms, SCC2 requires a functional PHD domain during meiosis in land plants.

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New insights into cohesin loading

Cited by 30 publications

References 98 publications

A Novel Role for α-Importins and Akirin in Establishment of Meiotic Sister Chromatid Cohesion in Caenorhabditis elegans

A Novel Role for α-Importins and Akirin in Establishment of Meiotic Sister Chromatid Cohesion in Caenorhabditis elegans

A Topology-Centric View on Mitotic Chromosome Architecture

The cohesin loader SCC2 contains a PHD finger that is required for meiosis in land plants

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