scholarly journals Synthetic hybrids of six yeast species

2019 ◽  
Author(s):  
David Peris ◽  
William G. Alexander ◽  
Kaitlin J. Fisher ◽  
Ryan V. Moriarty ◽  
Mira G. Basuino ◽  
...  
Keyword(s):  
Iterative Method ◽  
Chromosome Segregation ◽  
Chromosomal Instability ◽  
Genome Stability ◽  
Yeast Species ◽  
Potential Applications ◽  
Synthetic Hybrids ◽  
Evolutionary Radiations ◽  
Multiple Species ◽  
Species Hybrids

AbstractAllopolyploidy generates diversity by increasing the number of copies and sources of chromosomes. Many of the best-known evolutionary radiations, crops, and industrial organisms are ancient or recent allopolyploids. Allopolyploidy promotes differentiation and facilitates adaptation to new environments, but the tools to test its limits are lacking. Here we develop an iterative method to combine the genomes of multiple budding yeast species, generating Saccharomyces allopolyploids of an unprecedented scale. Chromosomal instability and cell size increased dramatically as additional copies of the genome were added, but we were able to construct synthetic hybrids of up to six species. The six-species hybrids initially grew slowly, but they rapidly adapted when selection to a novel environment was applied, even as they retained traits from multiple species. These new synthetic yeast hybrids have potential applications for the study of polyploidy, genome stability, chromosome segregation, cancer, and bioenergy.One sentence summaryWe constructed six-species synthetic hybrids and showed that they were chromosomally unstable but able to adapt rapidly.

scholarly journals Virulence protein VirD5 ofAgrobacterium tumefaciensbinds to kinetochores in host cells via an interaction with Spt4

2017 ◽  
Vol 114 (38) ◽  
pp. 10238-10243 ◽  
Author(s):  
Xiaorong Zhang ◽  
G. Paul H. van Heusden ◽  
Paul J. J. Hooykaas
Keyword(s):  
Chromosome Segregation ◽  
High Frequency ◽  
Chromosomal Instability ◽  
Plant Cells ◽  
Tumor Formation ◽  
Host Cells ◽  
Infection Site ◽  
Virulence Proteins ◽  
Virulence Protein

The bacteriumAgrobacterium tumefacienscauses crown gall tumor formation in plants. During infection the bacteria translocate an oncogenic piece of DNA (transferred DNA, T-DNA) into plant cells at the infection site. A number of virulence proteins are cotransported into host cells concomitantly with the T-DNA to effectuate transformation. Using yeast as a model host, we find that one of these proteins, VirD5, localizes to the centromeres/kinetochores in the nucleus of the host cells by its interaction with the conserved protein Spt4. VirD5 promotes chromosomal instability as seen by the high-frequency loss of a minichromosome in yeast. By using both yeast and plant cells with a chromosome that was specifically marked by alacOrepeat, chromosome segregation errors and the appearance of aneuploid cells due to the presence of VirD5 could be visualized in vivo. Thus, VirD5 is a prokaryotic virulence protein that interferes with mitosis.

scholarly journals Milk exosome-derived miRNAs from water buffalo are implicated in immune response and metabolism process

2020 ◽  
Author(s):  
Zujing Chen ◽  
Yueqin Xie ◽  
Junyi Luo ◽  
Ting Chen ◽  
Qianyun Xi ◽  
...  
Keyword(s):  
Functional Analysis ◽  
Buffalo Milk ◽  
Cow Milk ◽  
Lactation Period ◽  
Bioactive Substances ◽  
Physiological Importance ◽  
Exosomal Mirnas ◽  
Potential Applications ◽  
Multiple Species ◽  
Exosomal Mirna

Abstract Background: Buffalo milk is rich in various nutritional components and bioactive substances that provide more essential health benefits to human body. Recently, exosome identified in the breast milk has been reported as a neotype nutrient and can mediate intercellular communication with exosomal miRNAs. In the present study, we therefore hypothesized that exosome-derived miRNAs from buffalo milk would play the potential physiological importance of consumption of buffalo milk.Results: We isolated exosomes from buffalo and cow milk samples that were obtained at mid-lactation period, and the exosomal miRNA profiles were then generated using miRNA-seq. In addition, miRNAomes of pig, human and panda milk exosomes were downloaded from GEO database. Finally, a total of 27 milk exosomal miRNA profiles that included 4 buffalo, 4 cow, 8 pig, 4 human and 7 panda were analyzed using the miRDeep2 program. A total of 558 unique miRNA candidates existed across all species, and the top 10 highly expressed miRNA were evolutionarily conserved across multiple species. Functional analysis revealed that these milk enriched miRNAs targeted 400 putative sites to modulate disease resistance, immune responsiveness and basic metabolism events. In addition, a total of 32 miRNAs in buffalo milk were significantly up-regulated compared with non-buffalo milks, while 16 were significantly down-regulated. Of interest, functional analysis showed that up-regulated miRNA were mainly related to host metabolism processes, while the predicted functions of down-regulated miRNAs were enriched in immune response.Conclusion: In this study, we explored the exosomal miRNAome differences between milks of different animals, expanding the theoretical basis for potential applications of the miRNA-containing vesicles.

scholarly journals Heterochromatin: Guardian of the Genome

2018 ◽  
Vol 34 (1) ◽  
pp. 265-288 ◽  
Author(s):  
Aniek Janssen ◽  
Serafin U. Colmenares ◽  
Gary H. Karpen
Keyword(s):  
Chromosome Segregation ◽  
Genome Stability ◽  
Constitutive Heterochromatin ◽  
Repetitive Sequences ◽  
Genome Integrity ◽  
Chromatin Domain ◽  
Cellular Processes ◽  
Eukaryotic Nucleus ◽  
And Function ◽  
Heterochromatin Structure

Constitutive heterochromatin is a major component of the eukaryotic nucleus and is essential for the maintenance of genome stability. Highly concentrated at pericentromeric and telomeric domains, heterochromatin is riddled with repetitive sequences and has evolved specific ways to compartmentalize, silence, and repair repeats. The delicate balance between heterochromatin epigenetic maintenance and cellular processes such as mitosis and DNA repair and replication reveals a highly dynamic and plastic chromatin domain that can be perturbed by multiple mechanisms, with far-reaching consequences for genome integrity. Indeed, heterochromatin dysfunction provokes genetic turmoil by inducing aberrant repeat repair, chromosome segregation errors, transposon activation, and replication stress and is strongly implicated in aging and tumorigenesis. Here, we summarize the general principles of heterochromatin structure and function, discuss the importance of its maintenance for genome integrity, and propose that more comprehensive analyses of heterochromatin roles in tumorigenesis will be integral to future innovations in cancer treatment.

scholarly journals Aurora B kinase activity is regulated by SET/TAF1 on Sgo2 at the inner centromere

2019 ◽  
Vol 218 (10) ◽  
pp. 3223-3236 ◽  
Author(s):  
Yuichiro Asai ◽  
Koh Fukuchi ◽  
Yuji Tanno ◽  
Saki Koitabashi-Kiyozuka ◽  
Tatsuyuki Kiyozuka ◽  
...  
Keyword(s):  
Chromosome Segregation ◽  
Chromosomal Instability ◽  
Kinase Activity ◽  
Fine Tuning ◽  
Aurora B ◽  
The Novel ◽  
Aurora B Kinase ◽  
Microtubule Attachment ◽  
Molecular Events

The accurate regulation of phosphorylation at the kinetochore is essential for establishing chromosome bi-orientation. Phosphorylation of kinetochore proteins by the Aurora B kinase destabilizes improper kinetochore–microtubule attachments, whereas the phosphatase PP2A has a counteracting role. Imbalanced phosphoregulation leads to error-prone chromosome segregation and aneuploidy, a hallmark of cancer cells. However, little is known about the molecular events that control the balance of phosphorylation at the kinetochore. Here, we show that localization of SET/TAF1, an oncogene product, to centromeres maintains Aurora B kinase activity by inhibiting PP2A, thereby correcting erroneous kinetochore–microtubule attachment. SET localizes at the inner centromere by interacting directly with shugoshin 2, with SET levels declining at increased distances between kinetochore pairs, leading to establishment of chromosome bi-orientation. Moreover, SET overexpression induces chromosomal instability by disrupting kinetochore–microtubule attachment. Thus, our findings reveal the novel role of SET in fine-tuning the phosphorylation level at the kinetochore by balancing the activities of Aurora B and PP2A.

scholarly journals The RAD51 recombinase protects mitotic chromatin in human cells

2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Isabel E. Wassing ◽  
Emily Graham ◽  
Xanita Saayman ◽  
Lucia Rampazzo ◽  
Christine Ralf ◽  
...  
Keyword(s):  
Chromosome Segregation ◽  
Genome Stability ◽  
Spindle Assembly Checkpoint ◽  
De Novo ◽  
Genomic Stability ◽  
Human Cells ◽  
Genome Integrity ◽  
Chromosomal Replication ◽  
Anaphase Onset ◽  
Mitotic Chromatin

AbstractThe RAD51 recombinase plays critical roles in safeguarding genome integrity, which is fundamentally important for all living cells. While interphase functions of RAD51 in maintaining genome stability are well-characterised, its role in mitosis remains contentious. In this study, we show that RAD51 protects under-replicated DNA in mitotic human cells and, in this way, promotes mitotic DNA synthesis (MiDAS) and successful chromosome segregation. In cells experiencing mild replication stress, MiDAS was detected irrespective of mitotically generated DNA damage. MiDAS broadly required de novo RAD51 recruitment to single-stranded DNA, which was supported by the phosphorylation of RAD51 by the key mitotic regulator Polo-like kinase 1. Importantly, acute inhibition of MiDAS delayed anaphase onset and induced centromere fragility, suggesting a mechanism that prevents the satisfaction of the spindle assembly checkpoint while chromosomal replication remains incomplete. This study hence identifies an unexpected function of RAD51 in promoting genomic stability in mitosis.

scholarly journals The yeast core spliceosome maintains genome integrity through R-loop prevention and α-tubulin expression

2018 ◽  
Author(s):  
Annie S. Tam ◽  
Veena Mathew ◽  
Tianna S. Sihota ◽  
Anni Zhang ◽  
Peter C. Stirling
Keyword(s):  
Gene Expression ◽  
Dna Replication ◽  
Chromosome Segregation ◽  
Genome Stability ◽  
Spindle Assembly Checkpoint ◽  
Genome Instability ◽  
Genome Integrity ◽  
Genome Maintenance ◽  
Maintenance Factors ◽  
Spindle Assembly Checkpoint Protein

To achieve genome stability cells must coordinate the action of various DNA transactions including DNA replication, repair, transcription and chromosome segregation. How transcription and RNA processing enable genome stability is only partly understood. Two predominant models have emerged: one involving changes in gene expression that perturb other genome maintenance factors, and another in which genotoxic DNA:RNA hybrids, called R-loops, impair DNA replication. Here we characterize genome instability phenotypes in a panel yeast splicing factor mutants and find that mitotic defects, and in some cases R-loop accumulation, are causes of genome instability. Genome instability in splicing mutants is exacerbated by loss of the spindle-assembly checkpoint protein Mad1. Moreover, removal of the intron from the α-tubulin gene TUB1 restores genome integrity. Thus, while R-loops contribute in some settings, defects in yeast splicing predominantly lead to genome instability through effects on gene expression.

scholarly journals Loss of CIC promotes mitotic dysregulation and chromosome segregation defects

2019 ◽  
Author(s):  
Suganthi Chittaranjan ◽  
Jungeun Song ◽  
Susanna Y. Chan ◽  
Stephen Dongsoo Lee ◽  
Shiekh Tanveer Ahmad ◽  
...  
Keyword(s):  
Cell Cycle ◽  
Chromosome Segregation ◽  
Mammalian Cells ◽  
Chromosomal Instability ◽  
Spindle Assembly Checkpoint ◽  
Tumour Suppressor ◽  
Cell Cycle Regulators ◽  
Loss Of Function ◽  
Wide Range ◽  
Cancer Types

AbstractBackgroundCIC is a transcriptional repressor inactivated by loss-of-function mutations in several cancer types, including gliomas, lung cancers, and gastric adenocarcinomas. CIC alterations and/or loss of CIC activity have been associated with poorer outcomes and more aggressive phenotypes across cancer types, which is consistent with the notion that CIC functions as a tumour suppressor across a wide range of contexts.ResultsUsing mammalian cells lacking functional CIC, we found that CIC deficiency was associated with chromosome segregation (CS) defects, resulting in chromosomal instability and aneuploidy. These CS defects were associated with transcriptional dysregulation of spindle assembly checkpoint and cell cycle regulators. We also identified novel CIC interacting proteins, including core members of the SWI/SNF complex, and showed that they cooperatively regulated the expression of genes involved in cell cycle regulation. Finally, we showed that loss of CIC and ARID1A cooperatively increased CS defects and reduced cell viability.ConclusionsOur study ascribes a novel role to CIC as an important regulator of the cell cycle and demonstrates that loss of CIC can lead to chromosomal instability and aneuploidy in human and murine cells through defects in CS, providing insight into the underlying mechanisms of CIC’s increasingly apparent role as a “pan-cancer” tumour suppressor.

scholarly journals GTSE1 tunes microtubule stability for chromosome alignment and segregation through MCAK inhibition

2016 ◽  
Author(s):  
Shweta Bendre ◽  
Arnaud Rondelet ◽  
Conrad Hall ◽  
Nadine Schmidt ◽  
Yu-Chih Lin ◽  
...  
Keyword(s):  
Cell Lines ◽  
Cancer Cell ◽  
Chromosome Segregation ◽  
Genome Stability ◽  
Cancer Cell Lines ◽  
Dynamic Regulation ◽  
Spindle Positioning ◽  
Chromosome Missegregation ◽  
Microtubule Stability ◽  
Chromosome Alignment

AbstractThe dynamic regulation of microtubules during mitosis is critical for accurate chromosome segregation and genome stability. Cancer cell lines with hyperstabilized kinetochore microtubules have increased segregation errors and elevated chromosomal instability (CIN), but the genetic defects responsible remain largely unknown. The microtubule depolymerase MCAK can influence CIN through its impact on microtubule stability, but how its potent activity is controlled in cells remains unclear. Here we show that GTSE1, a protein found overexpressed in aneuploid cancer cell lines and tumours, regulates microtubule stability during mitosis by inhibiting MCAK microtubule depolymerase activity. Cells lacking GTSE1 have defects in chromosome alignment and spindle positioning due to microtubule instability caused by excess MCAK activity. Reducing GTSE1 levels in CIN cancer cell lines reduces chromosome missegregation defects, while artificially inducing GTSE1 levels in chromosomally stable cells elevates chromosome missegregation and CIN. Thus GTSE1 inhibition of MCAK activity regulates the balance of microtubule stability that determines the fidelity of chromosome alignment, segregation, and chromosomal stability.

scholarly journals The copy-number and varied strengths of MELT motifs in Spc105 balance the strength and responsiveness the Spindle Assembly Checkpoint

2020 ◽  
Author(s):  
Babhrubahan Roy ◽  
Simon JY Han ◽  
Adrienne N. Fontan ◽  
Ajit P. Joglekar
Keyword(s):  
Chromosome Segregation ◽  
Copy Number ◽  
Genome Stability ◽  
Spindle Assembly Checkpoint ◽  
Spindle Assembly ◽  
Evolutionary Trend ◽  
Binding Affinities ◽  
Chromosome Missegregation ◽  
Anaphase Onset ◽  
Maintain Genome Stability

SummaryThe Spindle Assembly Checkpoint (SAC) maintains genome stability while enabling timely anaphase onset. To maintain genome stability, the SAC must be strong so that it delays cell division even if one chromosome is unattached, but for timely anaphase onset, it must be responsive to silencing mechanisms. How it meets these potentially antagonistic requirements is unclear. Here we show that the balance between SAC strength and responsiveness is determined by the number of ‘MELT’ motifs in the kinetochore protein Spc105/KNL1 and their Bub3-Bub1 binding affinities. Spc105/KNL1 must contain many strong MELT motifs to prevent chromosome missegregation, but not too many, because this delays SAC silencing and anaphase onset. We demonstrate this by constructing a Spc105 variant that trades SAC responsiveness for significantly improved chromosome segregation accuracy. We propose that the necessity of balancing SAC strength with responsiveness drives the evolutionary trend of MELT motif number amplification and degeneration of their functionally optimal amino acid sequence.

scholarly journals Two XMAP215/TOG microtubule polymerases, Alp14 and Dis1, play non-exchangeable, distinct roles in microtubule organisation in fission yeast

2019 ◽  
Author(s):  
Masashi Yukawa ◽  
Tomoki Kawakami ◽  
Corinne Pinder ◽  
Takashi Toda
Keyword(s):  
Fission Yeast ◽  
Chromosome Segregation ◽  
Genome Stability ◽  
Spindle Assembly ◽  
Mitotic Progression ◽  
Spindle Microtubule ◽  
Microtubule Associated Proteins ◽  
Spatial Regulation ◽  
Associated Proteins ◽  
Microtubule Formation

AbstractProper bipolar spindle assembly underlies accurate chromosome segregation. A cohort of microtubule-associated proteins orchestrates spindle microtubule formation in a spatiotemporally coordinated manner. Among them, the conserved XMAP215/TOG family of microtubule polymerase plays a central role in spindle assembly. In fission yeast, two XMAP215/TOG members, Alp14 and Dis1, share essential roles in cell viability; however how these two proteins functionally collaborate remains undetermined. Here we show the functional interplay and specification of Alp14 and Dis1. Creation of new mutant alleles of alp14, which display temperature sensitivity in the absence of Dis1, enabled us to conduct detailed analyses of a double mutant. We have found that simultaneous inactivation of Alp14 and Dis1 results in early mitotic arrest with very short, fragile spindles. Intriguingly, these cells often undergo spindle collapse, leading to a lethal “cut” phenotype. By implementing an artificial targetting system, we have shown that Alp14 and Dis1 are not functionally exchangeable and as such are not merely redundant paralogues. Intriguingly, while Alp14 promotes microtubule nucleation, Dis1 does not. Our results uncover that the intrinsic specification, not the spatial regulation, between Alp14 and Dis1 underlies the collaborative actions of these two XMAP215/TOG members in mitotic progression, spindle integrity and genome stability.

Sign in / Sign up

Export Citation Format

Share Document