bims-micesi 2025-08-03 papers

bims-micesi

Biomed News

on Mitotic cell signalling

Issue of 2025–08–03
twenty papers selected by
Valentina Piano, Uniklinik Köln

Cohesin-mediated stabilization of the CCAN complex at kinetochores in mitosis.
A brief historical perspective on cell cycle control of CENP-A assembly and inheritance.
NuMA mechanically reinforces the spindle independently of its partner dynein.
ZO-2 is a scaffold at the centriole and mitotic spindle poles that enhances microtubule stability and supports the proper development of mitotic spindles and cilia.
Assessment of Chromosome Congression Defects in Mammalian Oocytes.
Nuclear Tracking During Early Embryonic Divisions.
Zea mays meiotic spindle ultrastructure reveals kinetochore-microtubule interface and embedded membrane components.
Proteome of oocyte spindle identifies Ccdc69 regulates spindle assembly like "band-tightening spell".
Transient APC/C inactivation by mTOR boosts glycolysis during cell cycle entry.
Fixation and Expansion Microscopy of Xenopus Egg Extract Spindles.
KIF14 as a Dual Microtubule/F-Actin Binding Protein Contributing to Cytokinesis.
Ca2+-driven cytoplasmic backflow ensures spindle anchoring in fertilized mouse eggs.
Germline-restricted chromosome of songbirds has different centromere compared to regular chromosomes.
Using Photoactivatable GFP to Study Cytokinesis Dynamics in Early Development.
Proteins involved in cell division have broad developmental functions.
All roads lead to mitosis: a common requirement for DNA replication stress-dependent and -independent killing of BRCA-deficient cells.
Quantification of Cyclin-CDK dissociation constants using FCCS with green and near-infrared fluorescent proteins.
Discovery of the first-in-class Aurora B kinase selective degrader.
Alisertib and Barasertib Induce Cell Cycle Arrest and Mitochondria-Related Cell Death in Multiple Myeloma with Enhanced Efficacy Through Sequential Combination with BH3-Mimetics and Panobinostat.
Cross-Scale Hypergraph Neural Networks with Inter-Intra Constraints for Mitosis Detection.

Curr Biol. 2025 Jul 22. pii: S0960-9822(25)00877-2. [Epub ahead of print]

Cohesin-mediated stabilization of the CCAN complex at kinetochores in mitosis.

Julian Haase, Koly Aktar, Mary Kate Bonner, Leonard Colin, Hindol Gupta, Briana E Marinoni, David O Morgan, Alexander E Kelly.

  The constitutive centromere-associated network (CCAN) of the inner kinetochore links CENP-A-containing nucleosomes of the centromere to the outer kinetochore, ensuring accurate chromosome segregation during mitosis. CCAN binding at the centromere is stabilized upon mitotic entry, but the underlying mechanisms remain unclear. Here, we demonstrate that cohesin is essential for CCAN stability. The chromosomal passenger complex (CPC), independently of its kinase subunit Aurora B, regulates cohesin-mediated CCAN stability via heterochromatin protein-1 (HP1), Haspin kinase, and phosphorylation of the cohesin-release factor WAPL, which weakens WAPL's affinity for PDS5B. While cohesin depletion disrupts CCAN stability, neither separase-mediated cohesin cleavage nor depletion of the cohesion-essential Esco2 acetyltransferase affects CCAN stability, indicating that cohesin stabilizes the CCAN independently of sister chromatid cohesion. Furthermore, we show that WAPL phosphorylation maintains a centromere-proximal pool of cohesin and promotes the formation of the primary constriction. These findings establish a non-cohesive function of cohesin in stabilizing the CCAN during mitosis and suggest that cohesin-mediated organization of centromeric chromatin strengthens kinetochore engagement to ensure faithful chromosome segregation.

Keywords:  Aurora B; CCAN; CENP-C; CPC; HP1; WAPL; centromere; cohesin; kinetochore; non-cohesive

DOI:  https://doi.org/10.1016/j.cub.2025.07.011
Chromosome Res. 2025 Jul 26. 33(1): 15

A brief historical perspective on cell cycle control of CENP-A assembly and inheritance.

Grant Rowley, Lars E T Jansen.

  Centromeres provide the chromosomal scaffold for the assembly of the kinetochore complex, thereby linking replicated sister chromatids to the mitotic spindle, driving their segregation into nascent daughter cells. The location and maintenance of centromeres rely, in large part, on a unique conserved chromatin domain, defined by nucleosomes containing the histone H3 variant, Centromere Protein A (CENP-A), whose discovery 40 years ago we now celebrate. Current models place CENP-A, along with many of its orthologs, at the centre of a self-propagating epigenetic feedback loop that heritably maintains centromere position through mitotic and meiotic divisions. CENP-A is stably recycled through DNA replication but requires replenishment each cell cycle. In many organisms, assembly is restricted to G1 phase, indicating tight cell cycle control of the assembly machinery. Here, we provide a historical overview of the discoveries that led to current models of cell cycle control of centromere assembly, starting with early models of regulation to the intricate, multi-layered phosphoregulation revealed to date. Our review focuses primarily on the human and other animal systems, in which the current view is that negative and positive control through cyclin-dependent kinases and Polo-like kinase 1 combine to link CENP-A assembly to mitotic exit. Cell cycle-coupled CENP-A assembly has been attributed to so-called licensing or priming events. We discuss the validity of these models and terminology and highlight key outstanding questions that remain unanswered.

Keywords:  CENP-A; Centromere; Epigenetics; HJURP; Mis18 complex; Phosphoregulation

DOI:  https://doi.org/10.1007/s10577-025-09774-2
bioRxiv. 2024 Dec 01. pii: 2024.11.29.622360. [Epub ahead of print]

NuMA mechanically reinforces the spindle independently of its partner dynein.

Nathan H Cho, Merve Aslan, Ahmet Yildiz, Sophie Dumont.

Both motor and non-motor proteins organize microtubules to build the spindle and maintain it against opposing forces. NuMA, a long microtubule binding protein, is essential to spindle structure and function. NuMA recruits the motor dynein to spindle microtubule minus-ends to actively cluster them, but whether NuMA performs other spindle roles remains unknown. Here, we show that NuMA acts independently of dynein to passively reinforce the mammalian spindle. NuMA that cannot bind dynein is sufficient to protect spindle poles against fracture under external force. In contrast, NuMA with a shorter coiled-coil or disrupted self-interactions cannot protect spindle poles, and NuMA turnover differences cannot explain mechanical differences. In vitro , NuMA's C-terminus self-interacts and bundles microtubules without dynein, dependent on residues essential to pole protection in vivo . Together, this suggests that NuMA reinforces spindle poles by crosslinking microtubules, using its long coiled-coiled and self-interactions to reach multiple, far-reaching pole microtubules. We propose that NuMA acts as a mechanical "multitasker" targeting contractile motor activity and separately crosslinking microtubules, both functions synergizing to drive spindle mechanical robustness.

DOI: https://doi.org/10.1101/2024.11.29.622360
Cell Tissue Res. 2025 Jul 29.

ZO-2 is a scaffold at the centriole and mitotic spindle poles that enhances microtubule stability and supports the proper development of mitotic spindles and cilia.

Sara Vega-Torreblanca, Diana Cristina Pinto-Dueñas, Christian Hernández-Guzmán, Dolores Martín-Tapia, Lourdes Alarcón, Bibiana Chávez-Munguía, Lizbeth Salazar-Villatoro, Sirenia González-Pozos, Josué David Hernández-Varela, Leticia Ramírez-Martínez, Esther López-Bayghen, José Jorge Chanona-Pérez, Lorenza González-Mariscal.

  Previous studies revealed the presence of several tight junction (TJ) proteins in the centrosome and their interaction with various centriolar proteins, prompting us to analyze whether this also applies to the TJ protein ZO-2. Here, we found that ZO-2 colocalizes with CEP164 in the distal appendage of the mother centriole and is also present in the pericentriolar region, mitotic spindle poles, the basal body of primary cilia, and the tail of spermatozoa. The absence of ZO-2 altered the cellular content of centriolar proteins CEP164, centriolin, and CEP135, but did not change the morphology of centrioles. ZO-2 depletion inhibits the development of astral and mitotic spindle microtubules expressing EB1. At the spindle poles, ZO-2 depletion increases the accumulation of NuMA while reducing the levels of kinesin KIF14 and the TPX2 scaffold, and the accumulation of the kinase p-Aurora, leading to a decrease in mitotic spindle length, microtubule instability, and abnormal chromosome congression. KIF14, NuMA, and p-Aurora co-immunoprecipitate with ZO-2, and NuMA and Aurora-A bind to different segments of ZO-2. At the ciliary basal body, ZO-2 depletion reduces the content of CEP164, KIF14, and IFT-B protein IFT57, while increasing the expression of p-Aurora and pAKT. These changes block primary cilium development and the response to Sonic Hedgehog signaling pathway stimulation. These results suggest that, rather than being a centrosomal architectural component, ZO-2 enhances microtubule stability and serves as a scaffold that facilitates the adequate accumulation of spindle pole and centriole proteins, allowing proper poleward spindle microtubule flux and cilia development.

Keywords:  Centrosome; Mitotic spindle; Primary cilium; Spermatozoid; ZO-2

DOI:  https://doi.org/10.1007/s00441-025-03992-0
Methods Mol Biol. 2025 ;2946 125-135

Assessment of Chromosome Congression Defects in Mammalian Oocytes.

Adela Horakova, Marketa Konecna, Martin Anger.

  Congression of all chromosomes on the equatorial plane is in mitosis required for metaphase-anaphase transition, and for successful segregation of sister chromatids during anaphase. In contrast to somatic cells, mouse oocytes, which are undergoing the first meiotic division, are capable to undergo metaphase-anaphase transition without congression of all chromosomes. Consequently, oocytes exhibit an increased frequency of chromosome segregation errors, which might lead to aneuploidy. In various experimental conditions, for example, during gene function studies, or during evaluation of the effects of pharmaceutical inhibitors, it might be beneficial to assess chromosome congression in live oocytes. In this chapter, we describe all steps necessary for performing such experiments, including isolation of mouse oocytes, microinjection-free labeling of chromosomes and spindle, the time-lapse recording of chromosome division during meiosis I, using confocal live cell microscopy, and also steps necessary for data analysis.

Keywords:  Chromosome congression; Chromosomes; Live imaging; Metaphase; Oocyte; Spindle

DOI:  https://doi.org/10.1007/978-1-0716-4658-8_10
Methods Mol Biol. 2025 ;2946 151-161

Nuclear Tracking During Early Embryonic Divisions.

Yunan Ye, Hayden A Homer.

  Positioning of the largest organelle, the nucleus, provides important cues for the geometry of cell divisions and cell fate determination. A primary function of nuclear positioning is to determine the spindle position and cleavage plane localization during cell division. Thus, centrally located nuclei lead to symmetrical divisions typical of mitosis, and off-center spindles culminate in symmetry-breaking as in mammalian oocytes. More recently, nuclear positioning has also been implicated in regulating mechanotransduction and gene expression in mouse oocytes. In human embryos, equal blastomere size arising from symmetrical cleavage-stage divisions is associated with favorable developmental outcomes, whereas off-center nuclear positioning affects division symmetry that can derail development. Therefore, investigating the mechanisms involved in nuclear positioning is critical for understanding embryo biology and the basis for clinical infertility. Here, we describe a method involving confocal imaging for performing nuclear tracking during early embryonic divisions in mouse embryos.

Keywords:  Embryo; Nuclear positioning; Nuclear tracking; Oocyte; Time-lapse imaging; TrackMate

DOI:  https://doi.org/10.1007/978-1-0716-4658-8_12
Cytogenet Genome Res. 2025 Jul 29. 1-29

Zea mays meiotic spindle ultrastructure reveals kinetochore-microtubule interface and embedded membrane components.

Subin Myong, Jenna K Cosby, Brianna Padilla, David M Opozda, Jacob Kahn, Naima Akter, Eileen T O'Toole, Natalie J Nannas.

INTRODUCTION: Spindles are microtubules-based machines whose primary function is to accurately segregate chromosomes in both mitotic and meiotic cell division. The structure of spindles is critical for their function; errors in morphology or attachment to chromosomes leads to aneuploidy, potentially resulting in disease, infertility and lethality. Electron microscopy studies have yielded fine detail spindle ultrastructures in many plant and animal species, but no studies have investigated the spindle of Z.mays, a critical crop and cytogenetic model system.
METHODS: Here we use electron tomography (ET), reconstruction and computer modeling to obtain three-dimensional, nanometer-resolution of the Z.mays meiotic spindle. Structures such as microtubules, kinetochores, vesicles, membrane channels and nuclear envelope were modeled through a partial spindle reconstruction, and confirmed using immunostaining and live fluorescence microscopy.
RESULTS: ET revealed that maize spindles contain 8-18 kinetochore microtubules (kMTs) per kinetochore, which are approximately 776nm in diameter and 316nm in depth. Small ~37nm vesicles were identified, as well as larger (~5µm long, 800nm wide) membrane channels that stain positively for the ER-marker PDI (protein disulfide isomerase). Imaging of prophase meiotic cells revealed a cross-hatch microtubule arrangement in the perinuclear ring on the external surface of the nuclear envelope, which also contained type II nuclear groves with transnuclear microtubules passing from the nucleus to the cytoplasm.
CONCLUSIONS: Z.mays meiotic spindles are similar to animal counterparts with a comparable number of kMTs, and pre-spindle transnuclear microtubules, but also plant-specific features such as Golgi-derived vesicles to assist cell plate formation, internal ER membrane channels and a perinuclear microtubule ring that aids spindle assembly. Maize kinetochores have an electron-diffuse ball in cup morphology that is comparable in size to Drosophila kinetochores and larger than mammalian kinetochores.

DOI: https://doi.org/10.1159/000547002
Cell Mol Life Sci. 2025 Jul 30. 82(1): 292

Proteome of oocyte spindle identifies Ccdc69 regulates spindle assembly like "band-tightening spell".

Jia-Ni Guo, Liu Zhu, Tie-Gang Meng, Yi-Na Zhang, Si-Min Sun, Xue-Mei Yang, Bing-Wang Zhao, Yi-Ke Lu, Yuan-Hong Xu, Wei Yue, Zhiming Han, Catherine C L Wong, Zhen-Bo Wang.

  Meiotic spindle is an intricate structure and required for chromosome segregation and the proper meiotic progression during oocyte maturation, and its function is regulated by a complex network of proteins located at spindle and its peripheral region. However, proteome of meiotic spindle remains poorly characterized. Here, we acquired the proteomic profile of spindles isolated from metaphase I (MI) and metaphase II (MII) mouse oocytes. In particular, we identified Ccdc69 as a novel regulator of spindle assembly in mouse oocytes. Although deletion of Ccdc69 did not affect female fertility, the MI spindles were elongated in Ccdc69 knockout oocytes. Overexpression of Ccdc69 induced spindle defects by reducing microtubule formation and disturbing acentriolar microtubule organization centers (aMTOCs) distribution. Furthermore, Ccdc69 overexpression impaired kinetochore-microtubule (K-MT) attachment and delayed meiotic progression by abnormal activation of spindle assembly checkpoint (SAC). Taken together, our study depicts the proteome of spindles during mouse oocyte maturation and demonstrates that Ccdc69 regulates spindle assembly and meiotic progression the way similar to "The Tightening Spell of Sun Wukong's Golden Headband" in the famous Chinese Classic Journey to the West.

Keywords:  Ccdc69; Meiosis; Oocyte; Proteome; Spindle assembly

DOI:  https://doi.org/10.1007/s00018-025-05821-7
Nature. 2025 Jul 30.

Transient APC/C inactivation by mTOR boosts glycolysis during cell cycle entry.

Debasish Paul, Derek L Bolhuis, Hualong Yan, Sudipto Das, Xia Xu, Christina C Abbate, Lisa M M Jenkins, Michael J Emanuele, Thorkell Andresson, Jing Huang, John G Albeck, Nicholas G Brown, Steven D Cappell.

Mammalian cells entering the cell cycle favour glycolysis to rapidly generate ATP and produce the biosynthetic intermediates that are required for rapid biomass accumulation1. Simultaneously, the ubiquitin-ligase anaphase-promoting complex/cyclosome and its coactivator CDH1 (APC/CCDH1) remains active, allowing origin licensing and blocking premature DNA replication. Paradoxically, glycolysis is reduced by APC/CCDH1 through the degradation of key glycolytic enzymes2, raising the question of how cells coordinate these mutually exclusive events to ensure proper cell division. Here we show that cells resolve this paradox by transiently inactivating the APC/C during cell cycle entry, which allows a transient metabolic shift favouring glycolysis. After mitogen stimulation, rapid mTOR-mediated phosphorylation of the APC/C adapter protein CDH1 at the amino terminus causes it to partially dissociate from the APC/C. This partial inactivation of the APC/C leads to the accumulation of PFKFB3, a rate-limiting enzyme for glycolysis, promoting a metabolic shift towards glycolysis. Delayed accumulation of phosphatase activity later removes CDH1 phosphorylation, restoring full APC/C activity, and shifting cells back to favouring oxidative phosphorylation. Thus, cells coordinate the simultaneous demands of cell cycle progression and metabolism through an incoherent feedforward loop, which transiently inhibits APC/C activity to generate a pulse of glycolysis that is required for mammalian cell cycle entry.

DOI: https://doi.org/10.1038/s41586-025-09328-w
Bio Protoc. 2025 Jul 20. 15(14): e5396

Fixation and Expansion Microscopy of Xenopus Egg Extract Spindles.

Gabriel Guilloux, Maiko Kitaoka, Karel Mocaer, Claire Heichette, Laurence Duchesne, Rebecca Heald, Thierry Pecot, Romain Gibeaux.

  In vitro systems based on Xenopus egg extracts have elucidated many aspects of spindle assembly. Still, numerous unknowns remain, particularly concerning the variation in spindle morphologies. The X. laevis and X. tropicalis egg extract systems, which recapitulate diverse spindle sizes and architectures, serve as ideal tools to investigate the regulation of spindle morphometrics. However, fully understanding spindle architectural differences is hindered by the spindle's size and high microtubule density. Indeed, classical fluorescence microscopy lacks the resolution to detail the organization of spindle microtubules, and although electron tomography can distinguish individual microtubules, segmenting thousands of microtubules and tracking them across dozens of sections remains an unachieved challenge. Therefore, we set out to apply expansion microscopy to the study of Xenopus egg extract spindles. During this process, we realized that optimizing spindle fixation as well was crucial to preserve microtubule integrity. Here, we present an optimized fixation and expansion microscopy protocol that enables the study of spindle architecture in egg extracts of both X. laevis and X. tropicalis. Our method retains the fluorescence of rhodamine tubulins added to the extracts and allows for both pre- and post-expansion immunofluorescence analysis. Key features • Expansion of optimally fixed spindle assembled from egg extracts of X. leavis, X. tropicalis, and possibly others. • Retains the fluorescence of the rhodamine-tubulin that copolymerizes with endogenous Xenopus tubulin within spindle microtubules, allowing their imaging without immunolabeling. • Compatible with both pre- and post-expansion immunolabeling to increase labeling possibilities. • Optimized spindle fixation that best preserves microtubule integrity for expansion and can also be used without expansion for regular immunofluorescence experiments.

Keywords:  Egg extract; Expansion microscopy; Microtubule; Spindle; Xenopus

DOI:  https://doi.org/10.21769/BioProtoc.5396
Cytoskeleton (Hoboken). 2025 Jul 28.

KIF14 as a Dual Microtubule/F-Actin Binding Protein Contributing to Cytokinesis.

Yajie Wang, Changjun Zhu.

  Cytokinesis, the final step of cell division, necessitates precise coordination between the microtubule-based central spindle and the actomyosin contractile ring. KIF14, a member of the kinesin-3 family of motor proteins, has emerged as a crucial integrator of these cytoskeletal systems. This review consolidates recent advances in understanding KIF14's structural domains, its dual-binding capacity for microtubules and F-actin, and its mechanochemical characteristics. KIF14 collaborates with protein regulator of cytokinesis 1 (PRC1) to bundle and slide antiparallel microtubules, while phosphorylation mediated by NIMA related kinase 7 (Nek7) enables KIF14 to bind and transport Citron kinase (CIT-K) to the midbody. This process connects central spindle organization to RhoA-driven contractility. In addition, KIF14 interacts with centralspindlin components and actomyosin regulators, thereby reinforcing midzone integrity and promoting cleavage furrow ingression. Its persistent midbody localization and activity regulated by phosphorylation ensure the temporal coordination of late cytokinesis events. Collectively, these functions establish KIF14 as a dual-function integrator of spindle architecture and contractile-ring constriction, making it indispensable for successful cell division.

Keywords:  KIF14; cleavage furrow; cytokinesis; spindle midzone

DOI:  https://doi.org/10.1002/cm.70020
Curr Biol. 2025 Jul 23. pii: S0960-9822(25)00859-0. [Epub ahead of print]

Ca2+-driven cytoplasmic backflow ensures spindle anchoring in fertilized mouse eggs.

Takaya Totsuka, Miho Ohsugi, Takashi Akera.

  Female meiosis is highly asymmetric, producing a large egg and a small polar body to preserve maternal storage essential for embryogenesis. To achieve asymmetric division, the egg spindle must maintain its cortical position until fertilization completes meiosis. In mice, fertilization triggers chromosome segregation, followed by spindle rotation to achieve the perpendicular orientation relative to the cortex, leading to the extrusion of one set of chromosomes. However, it was unknown how the spindle maintains its cortical position while rotating. Here, we developed a high-resolution live-imaging method to investigate spindle dynamics during fertilization. Our results indicate that Ca2+ oscillations put the brakes on spindle rotation by transiently reversing cytoplasmic streaming and that this cytoplasmic backflow secures the spindle localization at the cortex. Mechanistically, Ca2+ oscillations drive cortical actomyosin contraction to induce the cytoplasmic backflow. Altogether, this work revealed a previously unknown role of Ca2+ oscillations in maintaining spindle position, ensuring the highly asymmetric divisions inherent to female meiosis.

Keywords:  Ca(2+) oscillations; actomyosin contraction; cytoplasmic streaming; fertilization; live imaging; meiosis II; mouse egg; second polar body extrusion; spindle dynamics

DOI:  https://doi.org/10.1016/j.cub.2025.06.073
Heredity (Edinb). 2025 Jul 30.

Germline-restricted chromosome of songbirds has different centromere compared to regular chromosomes.

Jakub Rídl, Dmitrij Dedukh, Zuzana Halenková, Stephen A Schlebusch, Vladimír Beneš, Mireia Osuna Lopez, Tomasz S Osiejuk, Francisco J Ruiz-Ruano, Alexander Suh, Tomáš Albrecht, Jiří Reif, Radka Reifová.

Centromeres are an important part of chromosomes which direct chromosome segregation during cell division. Their modifications can therefore explain the unusual mitotic and meiotic behaviour of certain chromosomes, such as the germline-restricted chromosome (GRC) of songbirds. This chromosome is eliminated from somatic cells during early embryogenesis and later also from male germ cells during spermatogenesis. Although the mechanism of elimination is not yet known, it is possible that it involves a modification of the centromeric sequence on the GRC, resulting in problems with the attachment of this chromosome to the mitotic or meiotic spindle and its lagging during anaphase, which eventually leads to its elimination from the nucleus. However, the repetitive nature and rapid evolution of centromeres make their identification and comparative analysis across species and chromosomes challenging. Here, we used a combination of cytogenetic and genomic approaches to identify the centromeric sequences of two closely related songbird species, the common nightingale (Luscinia megarhynchos) and the thrush nightingale (L. luscinia). We found a 436-bp satellite repeat present in the centromeric regions of all regular chromosomes (i.e., autosomes and sex chromosomes), making it a strong candidate for the centromeric repeat. This centromeric repeat was highly similar between the two nightingale species. Interestingly, hybridization of the probe to this satellite repeat on meiotic spreads suggested that this repeat is missing on the GRC. Our results indicate that the change of the centromeric sequence may underlie the unusual inheritance and programmed DNA elimination of the GRC in songbirds.

DOI: https://doi.org/10.1038/s41437-025-00779-5
Methods Mol Biol. 2025 ;2946 137-149

Using Photoactivatable GFP to Study Cytokinesis Dynamics in Early Development.

Filip Vasilev, Greg FitzHarris.

  Fluorescent protein photoconversion is a powerful approach that can be adapted to investigate various aspects of cellular behavior in diverse contexts. In somatic cells, fluorescent photoactivation of photoactivatable-GFP (PAGFP) has been used to accurately determine the timing of plasma membrane abscission, the final step of cell division that establishes two cytoplasmically separate cells. Diffusion of photoactivated PAGFP from one cell into its sister cell shortly after mitosis indicates that abscission has not occurred, whereas photoactivated PAGFP that will not pass between cells suggests successful abscission. Here we have adapted this approach to enable investigation of abscission timing in the context of early mammalian embryos.

Keywords:  Cell division; Cytokinesis; Live cell imaging; Mouse embryo; Preimplantation development

DOI:  https://doi.org/10.1007/978-1-0716-4658-8_11
Dev Biol. 2025 Jul 25. pii: S0012-1606(25)00199-X. [Epub ahead of print]527 1-16

Proteins involved in cell division have broad developmental functions.

Jessica Benito, Elizabeth McCulla, Raisa Sumaiya, Jia L Song.

  Several proteins that are known to play a crucial role in mitosis may have alternative functions in embryogenesis. To test this hypothesis, we examined the spatial and temporal expression of the transcripts that encode proteins involved in mitosis throughout development, including those that encode for motor proteins, cytoskeletal elements and their modulators, vesicular transport, and cell cycle regulators. Results indicate that these transcripts have different expression patterns in various cell types. Interestingly, Cyclin Dependent Kinase 1 (CDK1), Polo Like Kinase 1 (PLK1), and Aurora kinase (Aurk) transcripts are expressed by endomesodermal cells of the blastula, the multipotent stem cells in coelomic pouches and/or the skeletogenic mesoderm of the gastrula that are not actively dividing. To further test that proteins important for mitosis may perform additional functions during embryogenesis, we treated embryos with CDK1, PLK1, and Aurk inhibitors, which resulted in a dose-dependent developmental arrest or delay and defects in gastrulation, skeletogenesis, and epithelial to mesenchymal transition. Further analysis indicates that the number of mesodermally-derived pigment cells is significantly less in CDK1 and PLK1 inhibited embryos and significantly increased in Aurk inhibited embryos. Importantly, the percentage of pigment cells undergoing cell proliferation in drug-treated embryos was not different than the control, indicating additional functions of CDK1, PLK1, and Aurk. Furthermore, PLK1 and Aurk may regulate ERK signaling to impact various developmental processes.

Keywords:  Cleavage stage; Gastrulation; Mitosis; Pigment cells; Sea urchin; Skeleton

DOI:  https://doi.org/10.1016/j.ydbio.2025.07.008
Mutat Res Rev Mutat Res. 2025 Jul 30. pii: S1383-5742(25)00028-6. [Epub ahead of print] 108557

All roads lead to mitosis: a common requirement for DNA replication stress-dependent and -independent killing of BRCA-deficient cells.

Sebastian Omar Siri, Ariel Abramovici Blasco, Ginette Moyano, Mares Ahlers, María Candelaria, Vanesa Gottifredi.

  The deficiency in breast cancer associated proteins 1 and 2 (BRCA1 and 2) causes an early and more frequent onset of tumor genesis and progression. Poly (ADP-ribose) polymerase inhibitors (PARPi) are selectively toxic towards BRCA1 and 2-deficient tumors, sparing the healthy cells from patients from side effects. In BRCA1 and 2 deficient tumors, PARPi-mediated cell death is characterized by the augmentation of replication stress (RS) and chromosome instability (CIN) including micronuclei (MN) accumulation, a source of swift genomic rearrangements. PARPi also cause resistance to treatments which indicates the need of treatment alternatives. In this review, we discuss potential options that, similarly to PARPi, selectively kill BRCA1 and/or 2 deficient tumors. Remarkably, while many of those alternatives also upregulate MN and other CIN variables, others cause a RS-independent and MN-independent cell killing. This is the case of the inhibitors of Rho-kinase (ROCK) and, potentially, mitotic kinase Polo like kinase 1 (PLK1). Such a mode of cell killing could be advantageous if attempting to either prevent or postpone the rise of resistance clones in the tumor population that survives the treatment.

Keywords:  BRCA1/2; PARP; PLK1, ROCK; chromosome instability; synthetic lethality

DOI:  https://doi.org/10.1016/j.mrrev.2025.108557
J Cell Sci. 2025 Jul 31. pii: jcs.263921. [Epub ahead of print]

Quantification of Cyclin-CDK dissociation constants using FCCS with green and near-infrared fluorescent proteins.

Aika Toyama, Yuhei Goto, Yuhei Yamauchi, Hironori Sugiyama, Yohei Kondo, Atsushi Mochizuki, Kazuhiro Aoki.

  The cell cycle is a highly coordinated process governed by cyclin-bound cyclin-dependent kinases (CDKs). While the interaction between cyclin and CDK are well-documented, the dissociation constants (Kd) between specific cyclin-CDK pairs within living cells remain poorly understood. Fluorescence cross-correlation spectroscopy (FCCS) enables the quantification of the Kd, but challenges remain in selecting an optimal pair of fluorescent molecules for FCCS in a living cell. In this study, we demonstrate that mNeonGreen and phycocyanobilin-bound miRFP670 represent a suitable pair for FCCS in living cells from the viewpoint of high photostability and low bleed-through. This fluorescent protein pair enables us to measure the Kd values of the cyclin-dependent kinase Cdc2 and B-type cyclin Cdc13 in fission yeast cells. Moreover, we roughly estimated the Kd values for 36 cyclin-CDK complexes, formed by 9 distinct cyclins and 4 CDKs, in mammalian cells, including unconventional cyclin-CDK pairs. These measurements suggest potential versatility of cyclin-CDK binding in cell cycle progression, with implications for understanding cell cycle regulation in both fission yeast and higher eukaryotes.

Keywords:  CDK; Cyclin; FCCS; FCS; IRFP

DOI:  https://doi.org/10.1242/jcs.263921
Eur J Med Chem. 2025 Jul 24. pii: S0223-5234(25)00771-8. [Epub ahead of print]298 118006

Discovery of the first-in-class Aurora B kinase selective degrader.

Xiaoping Hu, Kevin Graciano, Jianping Hu, Chang Liu, Jiuyi Zhang, Ling Xie, Xian Chen, Yan Xiong, Jian Jin, Jia Xu.

  Aurora kinases, consisting of Aurora A, B, and C, play critical roles in the regulation of mitosis and are frequently overexpressed in multiple types of cancer. Several Aurora kinase inhibitors have been developed and tested in clinical trials. Additionally, Aurora kinase A (AURKA) degraders and dual degraders of AURKA and Aurora kinase B (AURKB) have been reported. However, no AURKB selective degrader has been reported. Here, we report the discovery of the first-in-class AURKB selective degrader, MS44 (18), a von Hippel-Lindau (VHL) E3 ligase-recruiting proteolysis-targeting chimera (PROTAC), which potently degrades AURKB with a DC50 < 100 nM in a time-, concentration-, VHL-, and ubiquitin-proteasome system (UPS)-dependent manner. Compound 18 selectively degrades AURKB over AURKA and other related kinases. Notably, compound 18 effectively inhibits the proliferation in multiple cancer cell lines. Overall, compound 18 is a valuable chemical biology tool and a potential therapeutic. Our findings suggest that pharmacological degradation of AURKB could offer an alternative therapeutic approach for treating AURKB-dependent tumors.

Keywords:  AZD1152; Aurora B; Degrader; Kinase; PROTAC

DOI:  https://doi.org/10.1016/j.ejmech.2025.118006
Cancers (Basel). 2025 Jul 09. pii: 2290. [Epub ahead of print]17(14):

Alisertib and Barasertib Induce Cell Cycle Arrest and Mitochondria-Related Cell Death in Multiple Myeloma with Enhanced Efficacy Through Sequential Combination with BH3-Mimetics and Panobinostat.

Andrea Benedi, Manuel Beltrán-Visiedo, Nelia Jiménez-Alduán, Alfonso Serrano-Del Valle, Alberto Anel, Javier Naval, Isabel Marzo.

   BACKGROUND: The treatment landscape for multiple myeloma (MM) has significantly evolved in recent decades with novel therapies like proteasome inhibitors, immunomodulatory drugs and monoclonal antibodies. However, MM remains incurable, necessitating new pharmacological strategies. Mitotic kinases, such as Aurora proteins, have emerged as potential targets. Selective inhibitors of Aurora A and B,- alisertib (MLN8237) and barasertib (AZD1152), respectively, have shown anti-myeloma activity in preclinical studies, with alisertib demonstrating modest efficacy in early clinical trials.
METHODS AND RESULTS: This study investigated the mechanisms of action of alisertib and barasertib and their combination with antitumor agents in a panel of five MM cells lines. Both drugs induced cell cycle arrest phase and abnormal nuclear morphologies. Alisertib caused prolonged mitotic arrest, whereas barasertib induced transient arrest, both resulting in the activation of mitotic catastrophe. These findings revealed three potential outcomes: cell death, senescence, or polyploidy. High mitochondrial reactive oxygen species (mROS) were identified as possible drivers of cell death. Caspase inhibition reduced caspase-3 activation but did not prevent cell death. Interestingly, alisertib at low doses remained toxic to Bax/BakDKO cells, although mitochondrial potential disruption and cytochrome c release were observed. Sequential combinations of high-dose Aurora kinase inhibitors with BH3-mimetics, and in specific cases with panobinostat, showed a synergistic effect. Conversely, the simultaneous combination of alisertib and barasertib showed mostly antagonistic effects.
CONCLUSIONS: Alisertib and barasertib emerge as potential in vitro candidates against MM, although further studies are needed to validate their efficacy and to find the best combinations with other molecules.

Keywords:  Aurora kinase inhibitors; Bcl-2 proteins; cell death; mitotic arrest; multiple myeloma

DOI:  https://doi.org/10.3390/cancers17142290
Sensors (Basel). 2025 Jul 12. pii: 4359. [Epub ahead of print]25(14):

Cross-Scale Hypergraph Neural Networks with Inter-Intra Constraints for Mitosis Detection.

Jincheng Li, Danyang Dong, Yihui Zhan, Guanren Zhu, Hengshuo Zhang, Xing Xie, Lingling Yang.

  Mitotic figures in tumor tissues are an important criterion for diagnosing malignant lesions, and physicians often search for the presence of mitosis in whole slide imaging (WSI). However, prolonged visual inspection by doctors may increase the likelihood of human error. With the advancement of deep learning, AI-based automatic cytopathological diagnosis has been increasingly applied in clinical settings. Nevertheless, existing diagnostic models often suffer from high computational costs and suboptimal detection accuracy. More importantly, when assessing cellular abnormalities, doctors frequently compare target cells with their surrounding cells-an aspect that current models fail to capture due to their lack of intercellular information modeling, leading to the loss of critical medical insights. To address these limitations, we conducted an in-depth analysis of existing models and propose an Inter-Intra Hypergraph Neural Network (II-HGNN). Our model introduces a block-based feature extraction mechanism to efficiently capture deep representations. Additionally, we leverage hypergraph convolutional networks to process both intracellular and intercellular information, leading to more precise diagnostic outcomes. We evaluate our model on publicly available datasets under varying imaging conditions, and experimental results demonstrate that our approach consistently outperforms baseline models in terms of accuracy.

Keywords:  Thin-Prep cytologic test; cell detection; hypergraph neural network

DOI:  https://doi.org/10.3390/s25144359