scholarly journals Nipped-B, a Drosophila Homologue of Chromosomal Adherins, Participates in Activation by Remote Enhancers in the cut and Ultrabithorax Genes

Genetics ◽  
1999 ◽  
Vol 152 (2) ◽  
pp. 577-593 ◽  
Author(s):  
Robert A Rollins ◽  
Patrick Morcillo ◽  
Dale Dorsett
Keyword(s):  
Dna Repair ◽  
Sister Chromatid ◽  
Regulatory Region ◽  
Inhibitory Effect ◽  
Notch Receptor ◽  
Wing Margin ◽  
Transposon Insertion ◽  
Chromatid Cohesion ◽  
Complementation Groups ◽  
Mutant Phenotypes

Abstract How enhancers are able to activate promoters located several kilobases away is unknown. Activation by the wing margin enhancer in the cut gene, located 85 kb from the promoter, requires several genes that participate in the Notch receptor pathway in the wing margin, including scalloped, vestigial, mastermind, Chip, and the Nipped locus. Here we show that Nipped mutations disrupt one or more of four essential complementation groups: l(2)41Ae, l(2)41Af, Nipped-A, and Nipped-B. Heterozygous Nipped mutations modify Notch mutant phenotypes in the wing margin and other tissues, and magnify the effects that mutations in the cis regulatory region of cut have on cut expression. Nipped-A and l(2)41Af mutations further diminish activation by a wing margin enhancer partly impaired by a small deletion. In contrast, Nipped-B mutations do not diminish activation by the impaired enhancer, but increase the inhibitory effect of a gypsy transposon insertion between the enhancer and promoter. Nipped-B mutations also magnify the effect of a gypsy insertion in the Ultrabithorax gene. Gypsy binds the Suppressor of Hairy-wing insulator protein [Su(Hw)] that blocks enhancer-promoter communication. Increased insulation by Su(Hw) in Nipped-B mutants suggests that Nipped-B products structurally facilitate enhancer-promoter communication. Compatible with this idea, Nipped-B protein is homologous to a family of chromosomal adherins with broad roles in sister chromatid cohesion, chromosome condensation, and DNA repair.

scholarly journals SOLO: a meiotic protein required for centromere cohesion, coorientation, and SMC1 localization in Drosophila melanogaster

2010 ◽  
Vol 188 (3) ◽  
pp. 335-349 ◽  
Author(s):  
Rihui Yan ◽  
Sharon E. Thomas ◽  
Jui-He Tsai ◽  
Yukihiro Yamada ◽  
Bruce D. McKee
Keyword(s):  
Drosophila Melanogaster ◽  
Sister Chromatid ◽  
Sister Chromatid Cohesion ◽  
Early Prophase ◽  
Wild Type ◽  
Sister Chromatids ◽  
Chromatid Cohesion ◽  
Mutant Phenotypes ◽  
Meiosis I ◽  
Novel Protein

Sister chromatid cohesion is essential to maintain stable connections between homologues and sister chromatids during meiosis and to establish correct centromere orientation patterns on the meiosis I and II spindles. However, the meiotic cohesion apparatus in Drosophila melanogaster remains largely uncharacterized. We describe a novel protein, sisters on the loose (SOLO), which is essential for meiotic cohesion in Drosophila. In solo mutants, sister centromeres separate before prometaphase I, disrupting meiosis I centromere orientation and causing nondisjunction of both homologous and sister chromatids. Centromeric foci of the cohesin protein SMC1 are absent in solo mutants at all meiotic stages. SOLO and SMC1 colocalize to meiotic centromeres from early prophase I until anaphase II in wild-type males, but both proteins disappear prematurely at anaphase I in mutants for mei-S332, which encodes the Drosophila homologue of the cohesin protector protein shugoshin. The solo mutant phenotypes and the localization patterns of SOLO and SMC1 indicate that they function together to maintain sister chromatid cohesion in Drosophila meiosis.

scholarly journals The ATPases of cohesin interface with regulators to modulate cohesin-mediated DNA tethering

eLife ◽  
2015 ◽  
Vol 4 ◽  
Author(s):  
Gamze Çamdere ◽  
Vincent Guacci ◽  
Jeremiah Stricklin ◽  
Douglas Koshland
Keyword(s):  
Dna Repair ◽  
Transcriptional Regulation ◽  
Dna Binding ◽  
Sister Chromatid ◽  
Active Sites ◽  
Binding Activity ◽  
Second Step ◽  
Dna Binding Activity ◽  
Chromatid Cohesion ◽  
Biochemical Analyses

Cohesin tethers together regions of DNA, thereby mediating higher order chromatin organization that is critical for sister chromatid cohesion, DNA repair and transcriptional regulation. Cohesin contains a heterodimeric ATP-binding Cassette (ABC) ATPase comprised of Smc1 and Smc3 ATPase active sites. These ATPases are required for cohesin to bind DNA. Cohesin’s DNA binding activity is also promoted by the Eco1 acetyltransferase and inhibited by Wpl1. Recently we showed that after cohesin stably binds DNA, a second step is required for DNA tethering. This second step is also controlled by Eco1 acetylation. Here, we use genetic and biochemical analyses to show that this second DNA tethering step is regulated by cohesin ATPase. Furthermore, our results also suggest that Eco1 promotes cohesion by modulating the ATPase cycle of DNA-bound cohesin in a state that is permissive for DNA tethering and refractory to Wpl1 inhibition.

Sister chromatid cohesion and genome stability in vertebrate cells

2003 ◽  
Vol 31 (1) ◽  
pp. 263-265 ◽  
Author(s):  
C. Morrison ◽  
P. Vagnarelli ◽  
E. Sonoda ◽  
S. Takeda ◽  
W.C. Earnshaw
Keyword(s):  
Dna Repair ◽  
Chromosome Segregation ◽  
Sister Chromatid ◽  
Genome Stability ◽  
Sister Chromatid Cohesion ◽  
Spindle Poles ◽  
Chromatid Cohesion ◽  
Chromosomal Passenger ◽  
Passenger Protein

For successful eukaryotic mitosis, sister chromatid pairs remain linked after replication until their kinetochores have been attached to opposite spindle poles by microtubules. This linkage is broken at the metaphase–anaphase transition and the sisters separate. In budding yeast, this sister chromatid cohesion requires a multi-protein complex called cohesin. A key component of cohesin is Scc1/Mcd1 (Rad21 in fission yeast). Disruption of the chicken orthologue of Scc1 by gene targeting in DT40 cells causes premature sister chromatid separation. Cohesion between sister chromatids is likely to provide a substrate for post-replicative DNA repair by homologous recombination. In keeping with this role of cohesion, Scc1 mutants also show defects in the repair of spontaneous and induced DNA damage. Scc1-deficient cells frequently fail to complete metaphase chromosome alignment and show chromosome segregation defects, suggesting aberrant kinetochore function. Consistent with this, the chromosomal passenger protein, INCENP (inner centromere protein) fails to localize to centromeres. Survivin, another passenger protein and one which interacts with INCENP, also fails to localize to centromeres in Scc1-deficient cells. These results show that cohesin maintains genomic stability by ensuring appropriate DNA repair and equal chromosome segregation at mitosis.

scholarly journals Cohesin in space and time: architecture and oligomerization in vivo

2020 ◽  
Author(s):  
Siheng Xiang ◽  
Douglas Koshland
Keyword(s):  
Cell Cycle ◽  
Dna Repair ◽  
Transcription Regulation ◽  
Sister Chromatid ◽  
Critical Role ◽  
Coiled Coils ◽  
Biological Functions ◽  
Chromatid Cohesion ◽  
And Function

AbstractCohesin helps mediate sister chromatid cohesion, chromosome condensation, DNA repair and transcription regulation. Cohesin can tether two regions of DNA and can also extrude DNA loops. We interrogated cohesin architecture, oligomerization state and function of cohesin oligomers in vivo through proximity-dependent labeling of cohesin domains. Our results suggest that the hinge and head domains of cohesin both bind DNA, and that cohesin coiled coils bend, bringing the head and hinge together to form a butterfly conformation. Our data also suggest that cohesin efficiently oligomerizes on and off DNA. The levels of oligomers and their distribution on chromosomes are cell cycle regulated. Cohesin oligomerization is blocked by mutations in distinct domains of Smc3p and Mcd1p, or depletion of Pds5p. This unusual subset of mutations specifically blocks the maintenance of cohesion and condensation, suggesting that cohesin oligomerization plays a critical role in these biological functions.

scholarly journals SMC Complexes Are Guarded by the SUMO Protease Ulp2 Against SUMO-Chain-Mediated Turnover

2020 ◽  
Author(s):  
Ivan Psakhye ◽  
Dana Branzei
Keyword(s):  
Dna Repair ◽  
Ubiquitin Ligase ◽  
Sister Chromatid ◽  
Essential Role ◽  
Sumo Protease ◽  
Chromatid Cohesion ◽  
Multiple Processes ◽  
Simultaneous Loss ◽  
Structural Maintenance Of Chromosomes

ABSTRACTStructural maintenance of chromosomes (SMC) complexes, cohesin, condensin and Smc5/6, are essential for viability and participate in multiple processes, including sister chromatid cohesion, chromosome condensation, and DNA repair. Here we show that SUMO chains target all three SMC complexes and are antagonized by the SUMO protease Ulp2 to prevent their turnover. We uncover that the essential role of the cohesin-associated subunit Pds5 is to counteract SUMO chains jointly with Ulp2. Importantly, fusion of Ulp2 to kleisin Scc1 supports viability of PDS5 null cells and protects cohesin from proteasomal degradation mediated by the SUMO-targeted ubiquitin ligase Slx5/Slx8. The lethality of PDS5 deleted cells can also be bypassed by simultaneous loss of the PCNA unloader, Elg1, and the cohesin releaser, Wpl1, but only when Ulp2 is functional. Condensin and Smc5/6 complex are similarly guarded by Ulp2 against unscheduled SUMO-chain assembly, which we propose to time the availability of SMC complexes on chromatin.

scholarly journals Brca2, Pds5 and Wapl differentially control cohesin chromosome association and function

2017 ◽  
Author(s):  
Ziva Misulovin ◽  
Michelle Pherson ◽  
Maria Gause ◽  
Dale Dorsett
Keyword(s):  
Gene Expression ◽  
Dna Repair ◽  
Dna Replication ◽  
Chromosome Segregation ◽  
Sister Chromatid ◽  
Protein Complex ◽  
Sister Chromatid Cohesion ◽  
Sister Chromatids ◽  
Chromatid Cohesion ◽  
Active Genes

AbstractThe 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. Here we show that Brca2 opposes Pds5 function in sister chromatid cohesion by assaying precocious sister chromatid separation in metaphase spreads of cultured cells depleted for these proteins. By genome-wide chromatin immunoprecipitation we find that Pds5 facilitates SA cohesin subunit association with DNA replication origins and that Brca2 inhibits SA binding, mirroring their effects on sister chromatid cohesion. Cohesin binding is maximal at replication origins and extends outward to occupy active genes and regulatory sequences. Pds5 and Wapl, but not Brca2, limit the distance that cohesin extends from origins, thereby determining which active genes, enhancers and silencers bind cohesin. Using RNA-seq we find that Brca2, Pds5 and Wapl influence the expression of most genes sensitive to Nipped-B and cohesin, largely in the same direction. These findings demonstrate that Brca2 regulates sister chromatid cohesion and gene expression in addition to its canonical role in DNA repair and expand the known functions of accessory proteins in cohesin’s diverse functions.Author summaryThe cohesin protein complex has multiple functions in eukaryotic cells. It ensures that when a cell divides, the two daughter cells receive the correct number of chromosomes. It does this by holding together the sister chromatids that are formed when chromosomes are duplicated by DNA replication. Cohesin also helps repair damaged DNA, and to regulate genes important for growth and development. Even minor deficiencies in some proteins that regulate cohesin cause significant human birth defects. Here we investigated in Drosophila cells how three proteins, Pds5, Wapl and Brca2, determine where cohesin binds to chromosomes, control cohesin’s ability to hold sister chromatids together, and participate in gene expression. We find that Pds5 and Wapl work together, likely during DNA replication, to determine which genes bind cohesin by controlling how far cohesin spreads out along chromosomes. Pds5 is required for cohesin to hold sister chromatids together, and Brca2 counteracts this function. In contrast to the opposing roles in sister chromatid cohesion, Pds5 and Brca2 work together to facilitate control of gene expression by cohesin. Brca2 plays a critical role in DNA repair, and these studies expand the known roles for Brca2 by showing that it also regulates sister chromatid cohesion and gene expression. BRCA2 mutations in humans increase susceptibility to breast and ovarian cancer, and these findings raise the possibility that changes in chromosome segregation or gene expression might contribute to the increased cancer risk associated with these mutations.

scholarly journals A role for the Smc3 hinge domain in the maintenance of sister chromatid cohesion

2017 ◽  
Author(s):  
Brett Robison ◽  
Vincent Guacci ◽  
Douglas Koshland
Keyword(s):  
Sister Chromatid ◽  
Sister Chromatid Cohesion ◽  
Insertion Mutagenesis ◽  
Regulation Of Transcription ◽  
Dna Duplexes ◽  
Damage Repair ◽  
Chromatid Cohesion ◽  
Mutant Phenotypes ◽  
Random Insertion ◽  
Hinge Domain

AbstractCohesin is a conserved protein complex required for sister chromatid cohesion, chromosome condensation, DNA damage repair, and regulation of transcription. Although cohesin functions to tether DNA duplexes, the contribution of its individual domains to this activity remains poorly understood. We interrogated the Smc3p subunit of cohesin by random insertion mutagenesis. Analysis of a mutant in the Smc3p hinge revealed an unexpected role for this domain in cohesion maintenance and condensation. Further investigation revealed that the Smc3p hinge functions at a step following cohesin’s stable binding to chromosomes and independently of Smc3p’s regulation by the Eco1p acetyltransferase. Hinge mutant phenotypes resemble loss of Pds5p, which binds opposite the hinge near Smc3p’s head domain. We propose that a specific conformation of the Smc3p hinge and Pds5p cooperate to promote cohesion maintenance and condensation.

scholarly journals Cohesin architecture and clustering in vivo

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Siheng Xiang ◽  
Douglas Koshland
Keyword(s):  
Cell Cycle ◽  
Dna Repair ◽  
Transcription Regulation ◽  
Sister Chromatid ◽  
Coiled Coil ◽  
Sister Chromatid Cohesion ◽  
Chromosome Condensation ◽  
Cohesin Complex ◽  
Chromatid Cohesion

Cohesin helps mediate sister chromatid cohesion, chromosome condensation, DNA repair, and transcription regulation. We exploited proximity-dependent labeling to define the in vivo interactions of cohesin domains with DNA or with other cohesin domains that lie within the same or in different cohesin complexes. Our results suggest that both cohesin's head and hinge domains are proximal to DNA, and cohesin structure is dynamic with differential folding of its coiled coil regions to generate butterfly confirmations. This method also reveals that cohesins form ordered clusters on and off DNA. The levels of cohesin clusters and their distribution on chromosomes are cell cycle-regulated. Cohesin clustering is likely necessary for cohesion maintenance because clustering and maintenance uniquely require the same subset of cohesin domains and the auxiliary cohesin factor Pds5p. These conclusions provide important new mechanistic and biological insights into the architecture of the cohesin complex, cohesin–cohesin interactions, and cohesin's tethering and loop-extruding activities.

Sign in / Sign up

Export Citation Format

Share Document