bims-micesi 2024-04-21 papers

bims-micesi

Biomed News

on Mitotic cell signalling

Issue of 2024–04–21
thirteen papers selected by
Valentina Piano, Uniklinik Köln

Loss of the puromycin-sensitive aminopeptidase, PAM-1, triggers the spindle assembly checkpoint during the first mitotic division in Caenorhabditis elegans.
The kinesin motor Kif9 regulates centriolar satellite positioning and mitotic progression.
Entangling and disentangling mitotic chromosomes.
Nuclear release of eIF1 globally increases stringency of start-codon selection to preserve mitotic arrest physiology.
Mechanical stress combines with planar polarised patterning during metaphase to orient embryonic epithelial cell divisions.
CFDP1 regulates the stability of pericentric heterochromatin thereby affecting RAN GTPase activity and mitotic spindle formation.
Emerging role and function of SPDL1 in human health and diseases.
Heat stress impairs centromere structure and segregation of meiotic chromosomes in Arabidopsis.
A validation strategy to assess the role of phase separation as a determinant of macromolecular localization.
Phosphorylation of Mad1 at serine 18 by Mps1 is required for the full virulence of rice blast fungus, Magnaporthe oryzae.
Nuclear localization signal in nuclear receptor VDR facilitates the mitotic genome bookmarking by involving distinct amino acid residues.
Could the mitotic count improve personalized prognosis in melanoma patients?
Sustained ERK signaling promotes G2 cell cycle exit and primes cells for whole-genome duplication.

MicroPubl Biol. 2024 ;2024

Loss of the puromycin-sensitive aminopeptidase, PAM-1, triggers the spindle assembly checkpoint during the first mitotic division in Caenorhabditis elegans.

Aidan Durkan, Annalise Koup, Sarah E Bell, Rebecca Lyczak.

Puromycin-sensitive aminopeptidases have long been implicated in cell-cycle regulation, but the mechanism remains unknown. Here we show that mutations in the gene encoding the C. elegans puromycin-sensitive aminopeptidase, PAM-1 , cause chromosome segregation defects and an elongated mitosis in the one-cell embryo. Depleting a known regulator of the spindle assembly checkpoint (SAC), MDF-2 (MAD2 in humans), restores normal mitotic timing to pam-1 mutants but exacerbates the chromosome segregation defects. Thus, PAM-1 is required for proper attachment of chromosomes to the mitotic spindle and its absence triggers the SAC.

DOI: https://doi.org/10.17912/micropub.biology.001167
bioRxiv. 2024 Apr 03. pii: 2024.04.03.587821. [Epub ahead of print]

The kinesin motor Kif9 regulates centriolar satellite positioning and mitotic progression.

Juan Jesus Vicente, Michael Wagenbach, Justin Decarreau, Alex Zelter, Michael J MacCoss, Trisha N Davis, Linda Wordeman.

Centrosomes are the principal microtubule-organizing centers of the cell and play an essential role in mitotic spindle function. Centrosome biogenesis is achieved by strict control of protein acquisition and phosphorylation prior to mitosis. Defects in this process promote fragmentation of pericentriolar material culminating in multipolar spindles and chromosome missegregation. Centriolar satellites, membrane-less aggrupations of proteins involved in the trafficking of proteins toward and away from the centrosome, are thought to contribute to centrosome biogenesis. Here we show that the microtubule plus-end directed kinesin motor Kif9 localizes to centriolar satellites and regulates their pericentrosomal localization during interphase. Lack of Kif9 leads to aggregation of satellites closer to the centrosome and increased centrosomal protein degradation that disrupts centrosome maturation and results in chromosome congression and segregation defects during mitosis. Our data reveal roles for Kif9 and centriolar satellites in the regulation of cellular proteostasis and mitosis.

DOI: https://doi.org/10.1101/2024.04.03.587821
Mol Cell. 2024 Apr 18. pii: S1097-2765(24)00270-3. [Epub ahead of print]84(8): 1398-1400

Entangling and disentangling mitotic chromosomes.

Jonathan Baxter.

The DNA topological challenges generated by cellular manipulation of extremely long DNA fibers remain poorly understood. In this issue of Molecular Cell, Hildebrand et al.1 describe how mitotic chromosomes are self entangled and that disentanglement requires TOP2 activity in late mitosis.

DOI: https://doi.org/10.1016/j.molcel.2024.03.025
bioRxiv. 2024 Apr 06. pii: 2024.04.06.588385. [Epub ahead of print]

Nuclear release of eIF1 globally increases stringency of start-codon selection to preserve mitotic arrest physiology.

Jimmy Ly, Kehui Xiang, Kuan-Chung Su, Gunter B Sissoko, David P Bartel, Iain M Cheeseman.

Regulated start-codon selection has the potential to reshape the proteome through the differential production of uORFs, canonical proteins, and alternative translational isoforms. However, conditions under which start-codon selection is altered remain poorly defined. Here, using transcriptome-wide translation initiation site profiling, we reveal a global increase in the stringency of start-codon selection during mammalian mitosis. Low-efficiency initiation sites are preferentially repressed in mitosis, resulting in pervasive changes in the translation of thousands of start sites and their corresponding protein products. This increased stringency of start-codon selection during mitosis results from increased interactions between the key regulator of start- codon selection, eIF1, and the 40S ribosome. We find that increased eIF1-40S ribosome interactions during mitosis are mediated by the release of a nuclear pool of eIF1 upon nuclear envelope breakdown. Selectively depleting the nuclear pool of eIF1 eliminates the changes to translational stringency during mitosis, resulting in altered mitotic proteome composition. In addition, preventing mitotic translational rewiring results in substantially increased cell death and decreased mitotic slippage following treatment with anti-mitotic chemotherapeutics. Thus, cells globally control translation initiation stringency with critical roles during the mammalian cell cycle to preserve mitotic cell physiology.

DOI: https://doi.org/10.1101/2024.04.06.588385
Development. 2024 Apr 19. pii: dev.202862. [Epub ahead of print]

Mechanical stress combines with planar polarised patterning during metaphase to orient embryonic epithelial cell divisions.

Guy B Blanchard, Elena Scarpa, Leila Muresan, Bénédicte Sanson.

  The planar orientation of cell division (OCD) is important for epithelial morphogenesis and homeostasis. We ask how mechanics and antero-posterior (AP) patterning combine to influence the first divisions after gastrulation in the Drosophila embryonic epithelium. We analyse hundreds of cell divisions and show that stress anisotropy, notably from compressive forces, can reorient division directly in metaphase. Stress anisotropy influences the OCD by imposing cell elongation, despite mitotic rounding and over-riding interphase cell elongation. In strongly elongated cells, the mitotic spindle adapts its length to, and hence its orientation is constrained by, the cell long axis. Alongside mechanical cues, there is a tissue-wide bias of the mitotic spindle orientation towards AP-patterned planar polarised Myosin-II. This spindle bias is lost in an AP-patterning mutant. Thus, a patterning-induced mitotic spindle orientation bias over-rides mechanical cues in mildly elongated cells but the spindle is constrained to the high stress axis in strongly elongated cells.

Keywords:   Drosophila ; Axis extension; Cell division orientation; Mechanics; Morphogenesis; Myosin-II; Neighbour compression; Planar polarity; Steric hindrance; Stress anisotropy

DOI:  https://doi.org/10.1242/dev.202862
PLoS Biol. 2024 Apr;22(4): e3002574

CFDP1 regulates the stability of pericentric heterochromatin thereby affecting RAN GTPase activity and mitotic spindle formation.

Gokul Gopinathan, Qian Xu, Xianghong Luan, Thomas G H Diekwisch.

The densely packed centromeric heterochromatin at minor and major satellites is comprised of H3K9me2/3 histones, the heterochromatin protein HP1α, and histone variants. In the present study, we sought to determine the mechanisms by which condensed heterochromatin at major and minor satellites stabilized by the chromatin factor CFDP1 affects the activity of the small GTPase Ran as a requirement for spindle formation. CFDP1 colocalized with heterochromatin at major and minor satellites and was essential for the structural stability of centromeric heterochromatin. Loss of CENPA, HP1α, and H2A.Z heterochromatin components resulted in decreased binding of the spindle nucleation facilitator RCC1 to minor and major satellite repeats. Decreased RanGTP levels as a result of diminished RCC1 binding interfered with chromatin-mediated microtubule nucleation at the onset of mitotic spindle formation. Rescuing chromatin H2A.Z levels in cells and mice lacking CFDP1 through knock-down of the histone chaperone ANP32E not only partially restored RCC1-dependent RanGTP levels but also alleviated CFDP1-knockout-related craniofacial defects and increased microtubule nucleation in CFDP1/ANP32E co-silenced cells. Together, these studies provide evidence for a direct link between condensed heterochromatin at major and minor satellites and microtubule nucleation through the chromatin protein CFDP1.

DOI: https://doi.org/10.1371/journal.pbio.3002574
Open Med (Wars). 2024 ;19(1): 20240922

Emerging role and function of SPDL1 in human health and diseases.

Yuejiao Feng, Donghao Tang, Jie Wang.

  SPDL1 (spindle apparatus coiled-coil protein 1), also referred to as CCDC99, is a recently identified gene involved in cell cycle regulation. SPDL1 encodes a protein, hSpindly, which plays a critical role in the maintenance of spindle checkpoint silencing during mitosis. hSpindly coordinates microtubule attachment by promoting kinesin recruitment and mitotic checkpoint signaling. Moreover, the protein performs numerous biological functions in vivo and its aberrant expression is closely associated with abnormal neuronal development, pulmonary interstitial fibrosis, and malignant tumor development. In this review, we provide an overview of studies that reveal the characteristics of SPDL1 and of the protein encoded by it, as well as its biological and tumor-promoting functions.

Keywords:  CCDC99; SPDL1; cancer; cell cycle; hSpindly

DOI:  https://doi.org/10.1515/med-2024-0922
Elife. 2024 Apr 17. pii: RP90253. [Epub ahead of print]12

Heat stress impairs centromere structure and segregation of meiotic chromosomes in Arabidopsis.

Lucie Crhak Khaitova, Pavlina Mikulkova, Jana Pecinkova, Manikandan Kalidass, Stefan Heckmann, Inna Lermontova, Karel Riha.

  Heat stress is a major threat to global crop production, and understanding its impact on plant fertility is crucial for developing climate-resilient crops. Despite the known negative effects of heat stress on plant reproduction, the underlying molecular mechanisms remain poorly understood. Here, we investigated the impact of elevated temperature on centromere structure and chromosome segregation during meiosis in Arabidopsis thaliana. Consistent with previous studies, heat stress leads to a decline in fertility and micronuclei formation in pollen mother cells. Our results reveal that elevated temperature causes a decrease in the amount of centromeric histone and the kinetochore protein BMF1 at meiotic centromeres with increasing temperature. Furthermore, we show that heat stress increases the duration of meiotic divisions and prolongs the activity of the spindle assembly checkpoint during meiosis I, indicating an impaired efficiency of the kinetochore attachments to spindle microtubules. Our analysis of mutants with reduced levels of centromeric histone suggests that weakened centromeres sensitize plants to elevated temperature, resulting in meiotic defects and reduced fertility even at moderate temperatures. These results indicate that the structure and functionality of meiotic centromeres in Arabidopsis are highly sensitive to heat stress, and suggest that centromeres and kinetochores may represent a critical bottleneck in plant adaptation to increasing temperatures.

Keywords:  A. thaliana; cell biology; centremeres; centromeric histone; chromosomes; gene expression; meiosis; micronuclei; spindle assembly checkpoint

DOI:  https://doi.org/10.7554/eLife.90253
Mol Cell. 2024 Apr 12. pii: S1097-2765(24)00267-3. [Epub ahead of print]

A validation strategy to assess the role of phase separation as a determinant of macromolecular localization.

Marius Hedtfeld, Alicia Dammers, Carolin Koerner, Andrea Musacchio.

  Liquid-liquid phase separation (LLPS) of putative assembly scaffolds has been proposed to drive the biogenesis of membraneless compartments. LLPS scaffolds are usually identified through in vitro LLPS assays with single macromolecules (homotypic), but the predictive value of these assays remains poorly characterized. Here, we apply a strategy to evaluate the robustness of homotypic LLPS assays. When applied to the chromosomal passenger complex (CPC), which undergoes LLPS in vitro and localizes to centromeres to promote chromosome biorientation, LLPS propensity in vitro emerged as an unreliable predictor of subcellular localization. In vitro CPC LLPS in aqueous buffers was enhanced by commonly used crowding agents. Conversely, diluted cytomimetic media dissolved condensates of the CPC and of several other proteins. We also show that centromeres do not seem to nucleate LLPS, nor do they promote local, spatially restrained LLPS of the CPC. Our strategy can be adapted to purported LLPS scaffolds of other membraneless compartments.

Keywords:  Aurora B; Borealin; INCENP; Survivin; centromere; chromosomal passenger complex; condensate; kinetochore; liquid-liquid phase separation; membraneless organelle

DOI:  https://doi.org/10.1016/j.molcel.2024.03.022
Mol Plant Pathol. 2024 Apr;25(4): e13456

Phosphorylation of Mad1 at serine 18 by Mps1 is required for the full virulence of rice blast fungus, Magnaporthe oryzae.

Qiushi Chen, Ya Li, Tianjiao Shen, Rong Wang, Meiling Su, Qiong Luo, Hua Shi, Guodong Lu, Zonghua Wang, Kevin G Hardwick, Mo Wang.

  The spindle assembly checkpoint (SAC) proteins are conserved among eukaryotes safeguarding chromosome segregation fidelity during mitosis. However, their biological functions in plant-pathogenic fungi remain largely unknown. In this study, we found that the SAC protein MoMad1 in rice blast fungus (Magnaporthe oryzae) localizes on the nuclear envelope and is dispensable for M. oryzae vegetative growth and tolerance to microtubule depolymerizing agent treatment. MoMad1 plays an important role in M. oryzae infection-related development and pathogenicity. The monopolar spindle 1 homologue in M. oryzae (MoMps1) interacts with MoMad1 through its N-terminal domain and phosphorylates MoMad1 at Ser-18, which is conserved within the extended N termini of Mad1s from fungal plant pathogens. This phosphorylation is required for maintaining MoMad1 protein abundance and M. oryzae full virulence. Similar to the deletion of MoMad1, treatment with Mps1-IN-1 (an Mps1 inhibitor) caused compromised appressorium formation and decreased M. oryzae virulence, and these defects were dependent on its attenuating MoMad1 Ser-18 phosphorylation. Therefore, our study indicates the function of Mad1 in rice blast fungal pathogenicity and sheds light on the potential of blocking Mad1 phosphorylation by Mps1 to control crop fungal diseases.

Keywords:  Mad1; Mps1; pathogenicity; phosphorylation; rice blast fungus

DOI:  https://doi.org/10.1111/mpp.13456
Mol Cell Endocrinol. 2024 Apr 13. pii: S0303-7207(24)00089-3. [Epub ahead of print]589 112233

Nuclear localization signal in nuclear receptor VDR facilitates the mitotic genome bookmarking by involving distinct amino acid residues.

Jyoti Kashyap, Ayushi Chhabra, Neha Kumari, Rakesh K Tyagi.

  Mitotic genome-bookmarking preserves epigenetic information, re-establishing progenitor's gene expression profile through transcription factors, chromatin remodelers, and histone modifiers, thereby regulating cell fate and lineage commitment post-mitotically in progeny cells. Our recent study revealed that the constitutive association of VDR with mitotic chromatin involves its DNA-binding domain. However, amino acid residues in this domain, crucial for genome bookmarking, remain elusive. This study demonstrates that nuclear localization signal (NLS) residues between 49 and 55 amino acids in VDR are essential for receptor-chromatin interaction during mitosis. Furthermore, it is revealed that both bipartite nature of VDR-NLS region and N-terminally located positively charged arginine residues are critical for its 'genome-bookmarking' property. Since mitotic chromatin association of heterodimeric partner RXR depends on VDR-chromatin association, interventions in VDR binding also abort RXR-chromatin interaction. Overall, this study documents the mechanistic details underlying VDR-chromatin interactions in genome-bookmarking behavior, potentially aiding in comprehending VDR-mediated diseases attributed to certain SNPs.

Keywords:  DNA binding domain; Genome bookmarking; Nuclear localization signal; Nuclear receptor; Retinoid X-receptor; Vitamin D receptor

DOI:  https://doi.org/10.1016/j.mce.2024.112233
PLoS One. 2024 ;19(4): e0302309

Could the mitotic count improve personalized prognosis in melanoma patients?

Alessandra Buja, Massimo Rugge, Claudia Cozzolino, Francesca Dossi, Manuel Zorzi, Antonella Vecchiato, Giuseppe de Luca, Paolo Del Fiore, Saveria Tropea, Luigi dall'Olmo, Carlo Riccardo Rossi, Giovanna Boccuzzo, Simone Mocellin.

A number of studies have indicated that the mitotic rate may be a predictive factor for poor prognosis in melanoma patients. The aim of this study was to investigate whether the mitotic rate is associated with other prognostic clinical and anatomopathological characteristics. After adjusting for other anatomopathological characteristics, we then verified the prognostic value of the number of mitoses, determining in which population subgroup this variable may have greater prognostic significance on 3-year mortality. The Veneto Cancer Registry (Registro Tumori del Veneto-RTV), a high-resolution population-based dataset covering the regional population of approximately 4.9 million residents, served as the clinical data source for the analysis. Inclusion criteria included all incident cases of invasive cutaneous malignant melanoma recorded in the RTV in 2015 (1,050 cases) and 2017 (1,205 cases) for which the number of mitoses was available. Mitotic classes were represented by Kaplan-Meier curves for short-term overall survival. Cox regression calculated hazard ratios in multivariable models to evaluate the independent prognostic role of different mitotic rate cut-offs. The results indicate that the mitotic rate is associated with other survival prognostic factors: the variables comprising the TNM stage (e.g., tumor thickness, ulceration, lymph node status and presence of metastasis) and the characteristics that are not included in the TNM stage (e.g., age, site of tumor, type of morphology, growth pattern and TIL). Moreover, this study demonstrated that, even after adjusting for these prognostic factors, mitoses per mm2 are associated with higher mortality, particularly in T2 patients. In conclusion, these findings revealed the need to include the mitotic rate in the histological diagnosis because it correlates with the prognosis as an independent factor. The mitotic rate can be used to develop a personalized medicine approach in the treatment and follow-up monitoring of melanoma patients.

DOI: https://doi.org/10.1371/journal.pone.0302309
Dev Cell. 2024 Apr 11. pii: S1534-5807(24)00200-4. [Epub ahead of print]

Sustained ERK signaling promotes G2 cell cycle exit and primes cells for whole-genome duplication.

Adler Guerrero Zuniga, Timothy J Aikin, Connor McKenney, Yovel Lendner, Alain Phung, Paul W Hook, Amy Meltzer, Winston Timp, Sergi Regot.

  Whole-genome duplication (WGD) is a frequent event in cancer evolution that fuels chromosomal instability. WGD can result from mitotic errors or endoreduplication, yet the molecular mechanisms that drive WGD remain unclear. Here, we use live single-cell analysis to characterize cell-cycle dynamics upon aberrant Ras-ERK signaling. We find that sustained ERK signaling in human cells leads to reactivation of the APC/C in G2, resulting in tetraploid G0-like cells that are primed for WGD. This process is independent of DNA damage or p53 but dependent on p21. Transcriptomics analysis and live-cell imaging showed that constitutive ERK activity promotes p21 expression, which is necessary and sufficient to inhibit CDK activity and which prematurely activates the anaphase-promoting complex (APC/C). Finally, either loss of p53 or reduced ERK signaling allowed for endoreduplication, completing a WGD event. Thus, sustained ERK signaling-induced G2 cell cycle exit represents an alternative path to WGD.

Keywords:  cell cycle dynamics; oncogenesis; signaling dynamics; whole-genome duplication

DOI:  https://doi.org/10.1016/j.devcel.2024.03.032