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Shintaro Yamada, Kazuto Kugou, Da-Qiao Ding, Yurika Fujita, Yasushi Hiraoka, Hiroshi Murakami, Kunihiro Ohta, Takatomi Yamada
Meiotic recombination ensures faithful chromosome segregation and confers genetic diversity to gametes, and thus, is a key DNA-templated reaction not only for sexual reproduction, but also evolution. This recombination is initiated by programmed DNA double strand breaks (DSBs), which are mainly formed at recombination hotspots. As meiotic DSB formation requires multiple proteins, it is regulated by chromatin structure. In particular, DSB occurs in a higher-order chromatin architecture termed "axis-loop", in which many loops protrude from proteinaceous axis...
March 16, 2018: Current Genetics
Sara Villa-Hernández, Rodrigo Bermejo
Proliferating cells need to accurately duplicate and pass their genetic material on to daughter cells. Problems during replication and partition challenge the structural and numerical integrity of chromosomes. Diverse mechanisms, as the DNA replication checkpoint, survey the correct progression of replication and couple it with other cell cycle events to preserve genome integrity. The structural maintenance of chromosomes (SMC) cohesin complex primarily contributes to chromosome duplication by mediating the tethering of newly replicated sister chromatids, thus assisting their equal segregation in mitosis...
March 16, 2018: Current Genetics
Camilla Björkegren, Laura Baranello
Although our knowledge of chromatin organization has advanced significantly in recent years, much about the relationships between different features of genome architecture is still unknown. Folding of mammalian genomes into spatial domains is thought to depend on architectural proteins, other DNA-binding proteins, and different forms of RNA. In addition, emerging evidence points towards the possibility that the three-dimensional organisation of the genome is controlled by DNA topology. In this scenario, cohesin, CCCTC-binding factor (CTCF), transcription, DNA supercoiling, and topoisomerases are integrated to dictate different layers of genome organization, and the contribution of all four to gene control is an important direction of future studies...
March 16, 2018: International Journal of Molecular Sciences
Min Jae Kang, Soo Min Ahn, Il Tae Hwang
Cornelia de Lange syndrome (CdLS) is a developmental disorder which is characterized by typical facial features, upper extremity malformations, and growth and cognitive delays. The genes involved in CdLS encode the cohesin complex and its associated proteins; and NIPBL mutations, which account for half of the cases, result in severe CdLS phenotypes. We describe a girl with CdLS, presenting with typical facial dysmorphism, cleft palate, hypertrichosis, upper limb hypertonicity, flexion contracture of elbows, micromelia, bilateral hearing loss, gastroesophageal reflux, and severe pyloric stenosis...
January 2018: Annals of Clinical and Laboratory Science
Jialiang Huang, Kailong Li, Wenqing Cai, Xin Liu, Yuannyu Zhang, Stuart H Orkin, Jian Xu, Guo-Cheng Yuan
Recent studies have highlighted super-enhancers (SEs) as important regulatory elements for gene expression, but their intrinsic properties remain incompletely characterized. Through an integrative analysis of Hi-C and ChIP-seq data, here we find that a significant fraction of SEs are hierarchically organized, containing both hub and non-hub enhancers. Hub enhancers share similar histone marks with non-hub enhancers, but are distinctly associated with cohesin and CTCF binding sites and disease-associated genetic variants...
March 5, 2018: Nature Communications
Lanni Aquila, Joyce Ohm, Anna Woloszynska-Read
Stromal Antigen 2 (STAG2) is one of four components of the cohesin complex and predominantly functions in sister chromatid cohesion and segregation. STAG2 is the most frequently mutated cohesin subunit and was recently identified as a gene that is commonly altered in bladder cancer. The significance of these mutations remains controversial. Some studies associate loss of STAG2 expression with low stage and low grade bladder tumors, as well as with improved clinical outcomes. In other cases, STAG2 inactivation has been shown to be a predictor of worse outcome for these patients...
March 1, 2018: Pharmacological Research: the Official Journal of the Italian Pharmacological Society
Qi Yi, Qinfu Chen, Cai Liang, Haiyan Yan, Zhenlei Zhang, Xingfeng Xiang, Miao Zhang, Feifei Qi, Linli Zhou, Fangwei Wang
Heterochromatin protein-1 (HP1) is a key component of heterochromatin. Reminiscent of the cohesin complex which mediates sister-chromatid cohesion, most HP1 proteins in mammalian cells are displaced from chromosome arms during mitotic entry, whereas a pool remains at the heterochromatic centromere region. The function of HP1 at mitotic centromeres remains largely elusive. Here, we show that double knockout (DKO) of HP1α and HP1γ causes defective mitosis progression and weakened centromeric cohesion. While mutating the chromoshadow domain (CSD) prevents HP1α from protecting sister-chromatid cohesion, centromeric targeting of HP1α CSD alone is sufficient to rescue the cohesion defects in HP1 DKO cells...
February 28, 2018: EMBO Reports
Albert Galera-Prat, David Pantoja-Uceda, Douglas V Laurents, Mariano Carrión Vázquez
Bacterial cellulases are drawing increased attention as a means to obtain plentiful chemical feedstocks and fuels from renewable lignocellulosic biomass sources. Certain bacteria deploy a large extracellular multi-protein complex, called the cellulosome, to degrade cellulose. Scaffoldin, a key non-catalytic cellulosome component, is a large protein containing a cellulose-specific carbohydrate-binding module and several cohesin modules which bind and organize the hydrolytic enzymes. Despite the importance of the structure and protein/protein interactions of the cohesin module in the cellulosome, its structure in solution has remained unknown to date...
February 24, 2018: Archives of Biochemistry and Biophysics
Nuria Ferrandiz, Consuelo Barroso, Oana Telecan, Nan Shao, Hyun-Min Kim, Sarah Testori, Peter Faull, Pedro Cutillas, Ambrosious P Snijders, Monica P Colaiácovo, Enrique Martinez-Perez
The formation of haploid gametes from diploid germ cells requires the regulated two-step release of sister chromatid cohesion (SCC) during the meiotic divisions. Here, we show that phosphorylation of cohesin subunit REC-8 by Aurora B promotes SCC release at anaphase I onset in C. elegans oocytes. Aurora B loading to chromatin displaying Haspin-mediated H3 T3 phosphorylation induces spatially restricted REC-8 phosphorylation, preventing full SCC release during anaphase I. H3 T3 phosphorylation is locally antagonized by protein phosphatase 1, which is recruited to chromosomes by HTP-1/2 and LAB-1...
February 26, 2018: Nature Communications
D Valerio, A Luddi, V De Leo, D Labella, S Longobardi, P Piomboni
STUDY QUESTION: Are cohesins SA1/SA2 and the NAD-dependent deacetylase SIRT1 involved in telomere homeostasis of cumulus cells and thus eligible as biomarkers of follicular physiology and ovarian aging? SUMMARY ANSWER: SA1/SA2 cohesins and SIRT1 are associated with telomere length in cumulus cells and may be eligible biomarkers of follicular physiology and ovarian aging. WHAT IS KNOWN ALREADY: In somatic cells, cohesins SA1/SA2 mediate sister chromatid cohesion at the telomere termini (for SA1) and along chromatid arms (for SA2)...
February 22, 2018: Human Reproduction
Eulália M L da Silva, Susannah Rankin
Chromosome structure in both interphase and M-phase cells is strongly influenced by the action of the cohesin and condensin protein complexes. The cohesin complex tethers the identical copies of each chromosome, called sister chromatids, together following DNA replication and promotes normal interphase chromosome structure and gene expression. In contrast, condensin is active largely in M phase and promotes the compaction of individual chromosomes. The Xenopus egg extract system is uniquely suited to analyze the functions of both complexes...
February 23, 2018: Cold Spring Harbor Protocols
Mahipal Ganji, Indra A Shaltiel, Shveta Bisht, Eugene Kim, Ana Kalichava, Christian H Haering, Cees Dekker
It has been hypothesized that Structural Maintenance of Chromosomes (SMC) protein complexes such as condensin and cohesin spatially organize chromosomes by extruding DNA into large loops. Here, we provide unambiguous evidence for loop extrusion by directly visualizing the formation and processive extension of DNA loops by yeast condensin in real-time. We find that a single condensin complex is able to extrude tens of kilobase pairs of DNA at a force-dependent speed of up to 1,500 base pairs per second, using the energy of ATP hydrolysis...
February 22, 2018: Science
Somenath Datta, Richard M Sherva, Mart De La Cruz, Michelle T Long, Priya Roy, Vadim Backman, Sanjib Chowdhury, Hemant K Roy
The biological underpinnings for racial disparities in colorectal cancer (CRC) incidence remain to be elucidated. We have previously reported that the cohesin SA-1 down-regulation is an early event in colon carcinogenesis which is dramatically accentuated in African-Americans. In order to investigate the mechanism, we evaluated single nucleotide polymorphisms (SNPs) for association with SA-1-related outcomes followed by gene editing of candidate SNP. We observed that rs34149860 SNP was significantly associated with a lower colonic mucosal SA-1 expression and evaluation of public databases showed striking racial discordance...
February 19, 2018: Neoplasia: An International Journal for Oncology Research
Shukun Luo, Liang Tong
The cysteine protease separase opens the cohesin ring by cleaving its kleisin subunit and is a pivotal cell cycle factor for the transition from metaphase to anaphase. It is inhibited by forming a complex with the chaperone securin, and in vertebrates, also by the Cdk1-cyclin B1 complex. Separase is activated upon the destruction of securin or cyclin B1 by the proteasome, after ubiquitination by the anaphase-promoting complex/cyclosome (APC/C). Here we review recent structures of the active protease segment of Chaetomium thermophilum separase in complex with a substrate-mimic inhibitor and full-length Saccharomyces cerevisiae and Caenorhabditis elegans separase in complex with securin...
February 13, 2018: Current Opinion in Structural Biology
Ziva Misulovin, Michelle Pherson, Maria Gause, Dale Dorsett
The cohesin complex topologically encircles chromosomes and mediates sister chromatid cohesion to ensure accurate chromosome segregation upon cell division. Cohesin also participates in DNA repair and gene transcription. The Nipped-B-Mau2 protein complex loads cohesin onto chromosomes and the Pds5-Wapl complex removes cohesin. Pds5 is also essential for sister chromatid cohesion, indicating that it has functions beyond cohesin removal. The Brca2 DNA repair protein interacts with Pds5, but the roles of this complex beyond DNA repair are unknown...
February 15, 2018: PLoS Genetics
Sangita Pal, Spike D Postnikoff, Myrriah Chavez, Jessica K Tyler
The causal relationship between genomic instability and replicative aging is unclear. We reveal here that genomic instability at the budding yeast ribosomal DNA (rDNA) locus increases during aging, potentially due to the reduced cohesion that we uncovered during aging caused by the reduced abundance of multiple cohesin subunits, promoting increased global chromosomal instability. In agreement, cohesion is lost during aging at other chromosomal locations in addition to the rDNA, including centromeres. The genomic instability in old cells is exacerbated by a defect in DNA double-strand break (DSB) repair that we uncovered in old yeast...
February 2018: Science Advances
Kota Nagasaka, M Julius Hossain, M Julia Roberti, Jan Ellenberg, Toru Hirota
In the version of this Letter originally published, the authors omitted a citation of an early study demonstrating topoisomerase-II-dependent sister chromatid resolution. This reference has now been added to the reference list as reference number 28, and the relevant text has been amended as follows to include its citation: 'Resolution must reflect the removal of sister-sister contacts, and we show here that Topo-IIα-mediated release of DNA catenation plays a major role (Fig. 4), in agreement with previous findings28, whereas, surprisingly, cohesin dissociation is not strictly required (Fig...
February 12, 2018: Nature Cell Biology
Carmen Morales, Ana Losada
Replicated chromatids are held together from the time they emerge from the replication fork until their separation in anaphase. This process, known as cohesion, promotes faithful DNA repair by homologous recombination in interphase and ensures accurate chromosome segregation in mitosis. Identification of cohesin thirty years ago solved a long-standing question about the nature of the linkage keeping together the sister chromatids. Cohesin is an evolutionarily conserved complex composed of a heterodimer of the Structural Maintenance of Chromosomes (SMC) family of ATPases, Smc1 and Smc3, the kleisin subunit Rad21 and a Huntingtin/EF3/PP2A/Tor1 (HEAT) repeat domain-containing subunit named SA/STAG...
February 9, 2018: Current Opinion in Cell Biology
Maximilian Scheurer, Peter Rodenkirch, Marc Siggel, Rafael C Bernardi, Klaus Schulten, Emad Tajkhorshid, Till Rudack
Molecular dynamics (MD) simulations have become ubiquitous in all areas of life sciences. The size and model complexity of MD simulations are rapidly growing along with increasing computing power and improved algorithms. This growth has led to the production of a large amount of simulation data that need to be filtered for relevant information to address specific biomedical and biochemical questions. One of the most relevant molecular properties that can be investigated by all-atom MD simulations is the time-dependent evolution of the complex noncovalent interaction networks governing such fundamental aspects as molecular recognition, binding strength, and mechanical and structural stability...
February 6, 2018: Biophysical Journal
Xingkang Wu, Zhenyu Li, Yuemao Shen
BACKGROUND: Mitosis, the most dramatic event in the cell cycle, involves the reorganization of virtually all cellular components. Antimitotic agents are useful for dissecting the mechanism of this reorganization. Previously, we found that the small molecule CS1 accumulates cells in G2/M phase [1], but the mechanism of its action remains unknown. METHODS: Cell cycle analysis, live cell imaging and nuclear staining were used. Chromosomal morphology was detected by chromosome spreading...
January 30, 2018: Biochimica et Biophysica Acta
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