Within a eukaryotic cell, both lipid homeostasis and faithful cell cycle progression are meticulously orchestrated. The fission yeast Schizosaccharomyces pombe provides a powerful platform to study the intricate regulatory mechanisms governing these fundamental processes. In S. pombe, the Cbf11 and Mga2 proteins are transcriptional activators of non-sterol lipid metabolism genes, with Cbf11 also known as a cell cycle regulator. Despite sharing a common set of target genes, little was known about their functional relationship. This study reveals that Cbf11 and Mga2 function together in the same regulatory pathway, critical for both lipid metabolism and mitotic fidelity. Deletion of either gene results in a similar array of defects, including slow growth, dysregulated lipid homeostasis, impaired cell cycle progression (cut phenotype), abnormal cell morphology, perturbed transcriptomic and proteomic profiles, and compromised response to the stressors camptothecin and thiabendazole. Remarkably, the double deletion mutant does not exhibit a more severe phenotype compared to the single mutants. In addition, ChIP-nexus analysis reveals that both Cbf11 and Mga2 bind to nearly identical positions within the promoter regions of target genes. Interestingly, Mga2 binding appears to be dependent on the presence of Cbf11 and Cbf11 likely acts as a tether to DNA, while Mga2 is needed to activate the target genes. In addition, the study explores the distribution of Cbf11 and Mga2 homologs across fungi. The presence of both Cbf11 and Mga2 homologs in Basidiomycota contrasts with Ascomycota, which mostly lack Cbf11 but retain Mga2. This suggests an evolutionary rewiring of the regulatory circuitry governing lipid metabolism and mitotic fidelity. In conclusion, this study offers compelling support for Cbf11 and Mga2 functioning jointly to regulate lipid metabolism and mitotic fidelity in fission yeast.
- MeSH
- metabolismus lipidů * genetika MeSH
- mitóza * genetika MeSH
- regulace genové exprese u hub * MeSH
- Schizosaccharomyces pombe - proteiny * genetika metabolismus MeSH
- Schizosaccharomyces * genetika metabolismus MeSH
- transkripční faktory genetika metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- Schizosaccharomyces pombe - proteiny * MeSH
- transkripční faktory MeSH
The genomes of many plants, animals, and fungi frequently comprise dispensable B chromosomes that rely upon various chromosomal drive mechanisms to counteract the tendency of non-essential genetic elements to be purged over time. The B chromosome of rye - a model system for nearly a century - undergoes targeted nondisjunction during first pollen mitosis, favouring segregation into the generative nucleus, thus increasing their numbers over generations. However, the genetic mechanisms underlying this process are poorly understood. Here, using a newly-assembled, ~430 Mb-long rye B chromosome pseudomolecule, we identify five candidate genes whose role as trans-acting moderators of the chromosomal drive is supported by karyotyping, chromosome drive analysis and comparative RNA-seq. Among them, we identify DCR28, coding a microtubule-associated protein related to cell division, and detect this gene also in the B chromosome of Aegilops speltoides. The DCR28 gene family is neo-functionalised and serially-duplicated with 15 B chromosome-located copies that are uniquely highly expressed in the first pollen mitosis of rye.
- MeSH
- Aegilops genetika metabolismus MeSH
- chromozomy rostlin * genetika MeSH
- karyotypizace MeSH
- mitóza * genetika MeSH
- nondisjunkce genetická MeSH
- pyl genetika MeSH
- regulace genové exprese u rostlin MeSH
- rostlinné geny MeSH
- rostlinné proteiny genetika metabolismus MeSH
- žito * genetika MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- rostlinné proteiny MeSH
Most eukaryotes maintain the stability of their cellular genome sizes to ensure genome transmission to offspring through sexual reproduction. However, some alter their genome size by selectively eliminating parts or increasing ploidy at specific developmental stages. This phenomenon of genome elimination or whole genome duplication occurs in animal hybrids reproducing asexually. Such genome alterations occur during gonocyte development ensuring successful reproduction of these hybrids. Although multiple examples of genome alterations are known, the underlying molecular and cellular processes involved in selective genome elimination and duplication remain largely unknown. Here, we uncovered the process of selective genome elimination and genome endoreplication in hemiclonal fish hybrids from the genus Hypseleotris. Specifically, we examined parental sexual species H. bucephala and hybrid H. bucephala × H. gymnocephala (HB × HX). We observed micronuclei in the cytoplasm of gonial cells in the gonads of hybrids, but not in the parental sexual species. We also observed misaligned chromosomes during mitosis which were unable to attach to the spindle. Moreover, we found that misaligned chromosomes lag during anaphase and subsequently enclose in the micronuclei. Using whole mount immunofluorescent staining, we showed that chromatid segregation has failed in lagging chromosomes. We also performed three-dimensional comparative genomic hybridization (3D-CGH) using species-specific probes to determine the role of micronuclei in selective genome elimination. We repeatedly observed that misaligned chromosomes of the H. bucephala genome were preferentially enclosed in micronuclei of hybrids. In addition, we detected mitotic cells without a mitotic spindle as a potential cause of genome duplication. We conclude that selective genome elimination in the gonads of hybrids occurs through gradual elimination of individual chromosomes of one parental genome. Such chromosomes, unable to attach to the spindle, lag and become enclosed in micronuclei.
- Klíčová slova
- Asexual, Carp gudgeon, Gonocytes, Histone modification, Hybridogenesis, Micronucleus,
- MeSH
- chromozomy genetika MeSH
- délka genomu MeSH
- genom * MeSH
- gonády metabolismus MeSH
- hybridizace genetická MeSH
- mitóza genetika MeSH
- ryby genetika MeSH
- segregace chromozomů genetika MeSH
- zvířata MeSH
- Check Tag
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
Mitotic fidelity is crucial for the faithful distribution of genetic information into the daughter cells. Many fungal species, including the fission yeast Schizosaccharomyces pombe, undergo a closed form of mitosis, during which the nuclear envelope does not break down. In S. pombe, numerous processes have been identified that contribute to successful completion of mitosis. Notably, perturbations of lipid metabolism can lead to catastrophic mitosis and the 'cut' phenotype. It has been suggested that these mitotic defects are caused by insufficient membrane phospholipid supply during the anaphase nuclear expansion. However, it is not clear whether additional factors are involved. In this study, we characterized in detail mitosis in an S. pombe mutant lacking the Cbf11 transcription factor, which regulates lipid metabolism genes. We show that in cbf11Δ cells mitotic defects have already appeared prior to anaphase, before the nuclear expansion begins. Moreover, we identify altered cohesin dynamics and centromeric chromatin structure as additional factors affecting mitotic fidelity in cells with disrupted lipid homeostasis, providing new insights into this fundamental biological process.
- Klíčová slova
- CSL transcription factor, Chromatin structure, Closed mitosis, Cohesin, Lipid metabolism, Mitotic defects,
- MeSH
- koheziny MeSH
- metabolismus lipidů genetika MeSH
- mitóza genetika MeSH
- Schizosaccharomyces pombe - proteiny * metabolismus MeSH
- Schizosaccharomyces * metabolismus MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- Schizosaccharomyces pombe - proteiny * MeSH
Flowering plants contain a large number of cyclin families, each containing multiple members, most of which have not been characterized to date. Here, we analyzed the role of the B1 subclass of mitotic cyclins in cell cycle control during Arabidopsis development. While we reveal CYCB1;5 to be a pseudogene, the remaining four members were found to be expressed in dividing cells. Mutant analyses showed a complex pattern of overlapping, development-specific requirements of B1-type cyclins with CYCB1;2 playing a central role. The double mutant cycb1;1 cycb1;2 is severely compromised in growth, yet viable beyond the seedling stage, hence representing a unique opportunity to study the function of B1-type cyclin activity at the organismic level. Immunolocalization of microtubules in cycb1;1 cycb1;2 and treating mutants with the microtubule drug oryzalin revealed a key role of B1-type cyclins in orchestrating mitotic microtubule networks. Subsequently, we identified the GAMMA-TUBULIN COMPLEX PROTEIN 3-INTERACTING PROTEIN 1 (GIP1/MOZART) as an in vitro substrate of B1-type cyclin complexes and further genetic analyses support a potential role in the regulation of GIP1 by CYCB1s.
- Klíčová slova
- CDK, CYCB1, endosperm, microtubule nucleation, mitosis,
- MeSH
- Arabidopsis * genetika metabolismus MeSH
- buněčné dělení * MeSH
- cyklin B1 * genetika metabolismus MeSH
- mikrotubuly * metabolismus MeSH
- mitóza genetika MeSH
- proteiny huseníčku * genetika metabolismus MeSH
- transportní proteiny MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- cyklin B1 * MeSH
- GIP1 protein, Arabidopsis MeSH Prohlížeč
- proteiny huseníčku * MeSH
- transportní proteiny MeSH
Progression through the cell cycle is driven by cyclin-dependent kinases that control gene expression, orchestration of mitotic spindle, and cell division. To identify new regulators of the cell cycle, we performed transcriptomic analysis of human non-transformed cells expressing a fluorescent ubiquitination-based cell cycle indicator and identified 701 transcripts differentially expressed in G1 and G2 cells. Family with sequence similarity 110 member A (FAM110A) protein is highly expressed in G2 cells and localized at mitotic spindle and spindle poles during mitosis. Depletion of FAM110A impairs chromosomal alignment, delays metaphase-to-anaphase transition, and affects spindle positioning. Using mass spectrometry and immunoprecipitation, we identified casein kinase I (CK1) in complex with FAM110A during mitosis. CK1 phosphorylates the C-terminal domain of FAM110A in vitro, and inhibition of CK1 reduces phosphorylation of mitotic FAM110A. Wild-type FAM110A, but not the FAM110A-S252-S255A mutant deficient in CK1 phosphorylation, rescues the chromosomal alignment, duration of mitosis, and orientation of the mitotic spindle after depletion of endogenous FAM110A. We propose that CK1 regulates chromosomal alignment by phosphorylating FAM110A and promoting its interaction with mitotic spindle.
- Klíčová slova
- G2 phase, casein kinase 1, cell cycle, chromosomal alignment, mitosis,
- MeSH
- anafáze MeSH
- aparát dělícího vřeténka * metabolismus MeSH
- fosforylace MeSH
- HeLa buňky MeSH
- lidé MeSH
- mitóza genetika MeSH
- proteiny buněčného cyklu * metabolismus MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- proteiny buněčného cyklu * MeSH
B chromosomes are enigmatic elements in thousands of plant and animal genomes that persist in populations despite being nonessential. They circumvent the laws of Mendelian inheritance but the molecular mechanisms underlying this behavior remain unknown. Here we present the sequence, annotation, and analysis of the maize B chromosome providing insight into its drive mechanism. The sequence assembly reveals detailed locations of the elements involved with the cis and trans functions of its drive mechanism, consisting of nondisjunction at the second pollen mitosis and preferential fertilization of the egg by the B-containing sperm. We identified 758 protein-coding genes in 125.9 Mb of B chromosome sequence, of which at least 88 are expressed. Our results demonstrate that transposable elements in the B chromosome are shared with the standard A chromosome set but multiple lines of evidence fail to detect a syntenic genic region in the A chromosomes, suggesting a distant origin. The current gene content is a result of continuous transfer from the A chromosomal complement over an extended evolutionary time with subsequent degradation but with selection for maintenance of this nonvital chromosome.
- Klíčová slova
- B chromosome, genetic drive, nondisjunction, preferential fertilization,
- MeSH
- chromozomy rostlin genetika MeSH
- kukuřice setá genetika MeSH
- meióza genetika MeSH
- mitóza genetika MeSH
- molekulární evoluce * MeSH
- pyl genetika MeSH
- těhotenské proteiny genetika MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, U.S. Gov't, Non-P.H.S. MeSH
- Názvy látek
- těhotenské proteiny MeSH
Cyclin A2 is a key regulator of the cell cycle, implicated both in DNA replication and mitotic entry. Cyclin A2 participates in feedback loops that activate mitotic kinases in G2 phase, but why active Cyclin A2-CDK2 during the S phase does not trigger mitotic kinase activation remains unclear. Here, we describe a change in localisation of Cyclin A2 from being only nuclear to both nuclear and cytoplasmic at the S/G2 border. We find that Cyclin A2-CDK2 can activate the mitotic kinase PLK1 through phosphorylation of Bora, and that only cytoplasmic Cyclin A2 interacts with Bora and PLK1. Expression of predominately cytoplasmic Cyclin A2 or phospho-mimicking PLK1 T210D can partially rescue a G2 arrest caused by Cyclin A2 depletion. Cytoplasmic presence of Cyclin A2 is restricted by p21, in particular after DNA damage. Cyclin A2 chromatin association during DNA replication and additional mechanisms contribute to Cyclin A2 localisation change in the G2 phase. We find no evidence that such mechanisms involve G2 feedback loops and suggest that cytoplasmic appearance of Cyclin A2 at the S/G2 transition functions as a trigger for mitotic kinase activation.
- MeSH
- aktivace enzymů genetika MeSH
- buněčné jádro metabolismus MeSH
- chromatin metabolismus MeSH
- cyklin A2 genetika metabolismus MeSH
- cyklin-dependentní kinasa 2 nedostatek genetika MeSH
- cytoplazma metabolismus MeSH
- fosforylace genetika MeSH
- G2 fáze genetika MeSH
- HeLa buňky MeSH
- lidé MeSH
- mitóza genetika MeSH
- polo-like kinasa 1 MeSH
- poškození DNA genetika MeSH
- protein-serin-threoninkinasy metabolismus MeSH
- proteinkinasa CDC2 nedostatek genetika MeSH
- proteiny buněčného cyklu metabolismus MeSH
- protoonkogenní proteiny metabolismus MeSH
- S fáze genetika MeSH
- signální transdukce genetika MeSH
- transfekce MeSH
- vazba proteinů MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- bora protein, human MeSH Prohlížeč
- CCNA2 protein, human MeSH Prohlížeč
- CDK1 protein, human MeSH Prohlížeč
- CDK2 protein, human MeSH Prohlížeč
- chromatin MeSH
- cyklin A2 MeSH
- cyklin-dependentní kinasa 2 MeSH
- protein-serin-threoninkinasy MeSH
- proteinkinasa CDC2 MeSH
- proteiny buněčného cyklu MeSH
- protoonkogenní proteiny MeSH
Primary cilia play critical roles in development and disease. Their assembly and disassembly are tightly coupled to cell cycle progression. Here, we present data identifying KIF14 as a regulator of cilia formation and Hedgehog (HH) signaling. We show that RNAi depletion of KIF14 specifically leads to defects in ciliogenesis and basal body (BB) biogenesis, as its absence hampers the efficiency of primary cilium formation and the dynamics of primary cilium elongation, and disrupts the localization of the distal appendage proteins SCLT1 and FBF1 and components of the IFT-B complex. We identify deregulated Aurora A activity as a mechanism contributing to the primary cilium and BB formation defects seen after KIF14 depletion. In addition, we show that primary cilia in KIF14-depleted cells are defective in response to HH pathway activation, independently of the effects of Aurora A. In sum, our data point to KIF14 as a critical node connecting cell cycle machinery, effective ciliogenesis, and HH signaling.
- MeSH
- adaptorové proteiny signální transdukční metabolismus MeSH
- Aurora kinasa A antagonisté a inhibitory genetika metabolismus MeSH
- bazální tělíska metabolismus MeSH
- buněčný cyklus genetika MeSH
- chromatografie kapalinová MeSH
- cilie genetika metabolismus patologie MeSH
- HEK293 buňky MeSH
- interfáze fyziologie MeSH
- intracelulární signální peptidy a proteiny genetika metabolismus MeSH
- kineziny genetika metabolismus MeSH
- lidé MeSH
- mitóza genetika MeSH
- onkogenní proteiny genetika metabolismus MeSH
- protein-serin-threoninkinasy genetika metabolismus MeSH
- proteiny hedgehog metabolismus MeSH
- RNA interference MeSH
- signální transdukce genetika MeSH
- sodíkové kanály metabolismus MeSH
- tandemová hmotnostní spektrometrie MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Názvy látek
- adaptorové proteiny signální transdukční MeSH
- AURKA protein, human MeSH Prohlížeč
- Aurora kinasa A MeSH
- citron-kinase MeSH Prohlížeč
- FBF1 protein, human MeSH Prohlížeč
- intracelulární signální peptidy a proteiny MeSH
- KIF14 protein, human MeSH Prohlížeč
- kineziny MeSH
- onkogenní proteiny MeSH
- protein-serin-threoninkinasy MeSH
- proteiny hedgehog MeSH
- SCLT1 protein, human MeSH Prohlížeč
- sodíkové kanály MeSH
B chromosomes (Bs) are supernumerary chromosomes, which are often preferentially inherited. When transmission rates of chromosomes are higher than 0.5, not obeying the Mendelian law of equal segregation, the resulting transmission advantage is collectively referred to as 'chromosome drive'. Here we analysed the drive mechanism of Aegilops speltoides Bs. The repeat AesTR-183 of A. speltoides Bs, which also can be detected on the Bs of Aegilops mutica and rye, was used to track Bs during pollen development. Nondisjunction of CENH3-positive, tubulin interacting B sister chromatids and an asymmetric spindle during first pollen grain mitosis are key for the accumulation process. A quantitative flow cytometric approach revealed that, independent of the number of Bs present in the mother plant, Bs accumulate in the generative nuclei to > 93%. Nine out of 11 tested (peri)centromeric repeats were shared by A and B chromosomes. Our findings provide new insights into the process of chromosome drive. Quantitative flow cytometry is a useful and reliable method to study the drive frequency of Bs. Nondisjunction and unequal spindle organization accompany during first pollen mitosis the drive of A. speltoides Bs. The prerequisites for the drive process seems to be common in Poaceae.
- Klíčová slova
- Aegilops speltoides, asymmetric spindle, centromere, chromosome drive, chromosome nondisjunction, flow cytometry, pollen grain mitosis, supernumerary B chromosome,
- MeSH
- Aegilops genetika MeSH
- aparát dělícího vřeténka metabolismus MeSH
- buněčné jádro genetika MeSH
- centromera metabolismus MeSH
- chromozomy rostlin genetika MeSH
- konzervovaná sekvence genetika MeSH
- mitóza genetika MeSH
- nondisjunkce genetická * MeSH
- pyl genetika MeSH
- repetitivní sekvence nukleových kyselin genetika MeSH
- sekvence nukleotidů MeSH
- žito genetika MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
