bims-micesi 2023-05-21 papers

bims-micesi

Biomed News

on Mitotic cell signalling

Issue of 2023–05–21
eleven papers selected by
Valentina Piano, Uniklinik Köln

Stable kinetochore-microtubule attachment requires loop-dependent Ndc80-Ndc80 binding.
[Progress in the Study of Spindle Assembly Checkpoint in Lung Cancer].
Modification of the Neck Linker of KIF18A Alters Microtubule Subpopulation Preference.
Distinct regions of the kinesin-5 C-terminal tail are essential for mitotic spindle midzone localization and sliding force.
Cik1 and Vik1 Accessory Proteins Confer Distinct Functions to the Kinesin-14, Kar3.
Lactate fuels mitosis.
Disruption of the standard kinetochore in holocentric Cuscuta species.
Mitotic spindle positioning protein (MISP) is an actin bundler that senses ADP-actin and binds near the pointed ends of filaments.
Disruption of CDK7 signaling leads to catastrophic chromosomal instability coupled with a loss of condensin-mediated chromatin compaction.
MYO10 regulates genome stability and cancer inflammation through mediating mitosis.
Mitogen-Induced Defective Mitosis Transforms Neural Progenitor Cells.

EMBO J. 2023 May 19. e112504

Stable kinetochore-microtubule attachment requires loop-dependent Ndc80-Ndc80 binding.

Soumitra Polley, Helen Müschenborn, Melina Terbeck, Anna De Antoni, Ingrid R Vetter, Marileen Dogterom, Andrea Musacchio, Vladimir A Volkov, Pim J Huis In 't Veld.

  During cell division, kinetochores link chromosomes to spindle microtubules. The Ndc80 complex, a crucial microtubule binder, populates each kinetochore with dozens of copies. Whether adjacent Ndc80 complexes cooperate to promote microtubule binding remains unclear. Here we demonstrate that the Ndc80 loop, a short sequence that interrupts the Ndc80 coiled-coil at a conserved position, folds into a more rigid structure than previously assumed and promotes direct interactions between full-length Ndc80 complexes on microtubules. Mutations in the loop impair these Ndc80-Ndc80 interactions, prevent the formation of force-resistant kinetochore-microtubule attachments, and cause cells to arrest in mitosis for hours. This arrest is not due to an inability to recruit the kinetochore-microtubule stabilizing SKA complex and cannot be overridden by mutations in the Ndc80 tail that strengthen microtubule attachment. Thus, loop-mediated organization of adjacent Ndc80 complexes is crucial for stable end-on kinetochore-microtubule attachment and spindle assembly checkpoint satisfaction.

Keywords:  Ndc80; chromosome segregation; kinetochore; microtubule; spindle assembly checkpoint

DOI:  https://doi.org/10.15252/embj.2022112504
Zhongguo Fei Ai Za Zhi. 2023 Apr 20. 26(4): 310-318

[Progress in the Study of Spindle Assembly Checkpoint in Lung Cancer].

Xinchen Qin, Yao Zhang, Haijie Yu, Lijuan Ma.

  Spindle assembly checkpoint (SAC) is a protective mechanism for cells to undergo accurate mitosis. SAC prevented chromosome segregation when kinetochores were not, or incorrectly attached to microtubules in the anaphase of mitosis, thus avoiding aneuploid chromosomes in daughter cells. Aneuploidy and altered expression of SAC component proteins are common in different cancers, including lung cancer. Therefore, SAC is a potential new target for lung cancer therapy. Five small molecule inhibitors of monopolar spindle 1 (MPS1), an upstream component protein of SAC, have entered clinical trials. This article introduces the biological functions of SAC, summarizes the abnormal expression of SAC component proteins in various cancers and the research progress of MPS1 inhibitors, and expects to provide a reference for the future development of lung cancer therapeutic strategies targeting SAC components. .

Keywords:  Aneuploidy; Mitosis; Mitotic checkpoint complex; Spindle assembly checkpoint

DOI:  https://doi.org/10.3779/j.issn.1009-3419.2023.101.13
bioRxiv. 2023 May 02. pii: 2023.05.02.539080. [Epub ahead of print]

Modification of the Neck Linker of KIF18A Alters Microtubule Subpopulation Preference.

Katelyn A Queen, Alisa Cario, Christopher L Berger, Jason Stumpff.

Kinesins support many diverse cellular processes, including facilitating cell division through mechanical regulation of the mitotic spindle. However, how kinesin activity is controlled to facilitate this process is not well understood. Interestingly, post-translational modifications have been identified within the enzymatic region of all 45 mammalian kinesins, but the significance of these modifications has gone largely unexplored. Given the critical role of the enzymatic region in facilitating nucleotide and microtubule binding, it may serve as a primary site for kinesin regulation. Consistent with this idea, a phosphomimetic mutation at S357 in the neck- linker of KIF18A alters the localization of KIF18A within the spindle from kinetochore microtubules to peripheral microtubules. Changes in localization of KIF18A-S357D are accompanied by defects in mitotic spindle positioning and the ability to promote mitotic progression. This altered localization pattern is mimicked by a shortened neck-linker mutant, suggesting that KIF18A-S357D may cause the motor to adopt a shortened neck-linker like state that prevents KIF18A from accumulating at the plus-ends of kinetochore microtubules. These findings demonstrate that post-translational modifications in the enzymatic region of kinesins could be important for biasing their localization to particular microtubule subpopulations.

DOI: https://doi.org/10.1101/2023.05.02.539080
bioRxiv. 2023 May 01. pii: 2023.05.01.538972. [Epub ahead of print]

Distinct regions of the kinesin-5 C-terminal tail are essential for mitotic spindle midzone localization and sliding force.

Zachary R Gergely, Michele H Jones, Bojun Zhou, Cai Cash, J Richard McIntosh, Meredith D Betterton.

Kinesin-5 motor proteins play essential roles during mitosis in most organisms. Their tetrameric structure and plus-end-directed motility allow them to bind to and move along antiparallel microtubules, thereby pushing spindle poles apart to assemble a bipolar spindle. Recent work has shown that the C-terminal tail is particularly important to kinesin-5 function: the tail affects motor domain structure, ATP hydrolysis, motility, clustering, and sliding force measured for purified motors, as well as motility, clustering, and spindle assembly in cells. Because previous work has focused on presence or absence of the entire tail, the functionally important regions of the tail remain to be identified. We have therefore characterized a series of kinesin-5/Cut7 tail truncation alleles in fission yeast. Partial truncation causes mitotic defects and temperature-sensitive growth, while further truncation that removes the conserved BimC motif is lethal. We compared the sliding force generated by cut7 mutants using a kinesin-14 mutant background in which some microtubules detach from the spindle poles and are pushed into the nuclear envelope. These Cut7-driven protrusions decreased as more of the tail was truncated, and the most severe truncations produced no observable protrusions. Our observations suggest that the BimC motif and adjacent C-terminal amino acids are essential for sliding force, while the residues N-terminal to the BimC motif are more important for midzone localization. Spindle microtubule protrusions may be a useful tool to study sliding force generated by kinesin-5 motors.

DOI: https://doi.org/10.1101/2023.05.01.538972
J Cell Sci. 2023 May 19. pii: jcs.260621. [Epub ahead of print]

Cik1 and Vik1 Accessory Proteins Confer Distinct Functions to the Kinesin-14, Kar3.

Zane J Bergman, Jonathan J Wong, David G Drubin, Georjana Barnes.

  The budding yeast Saccharomyces cerevisiae has a closed mitosis in which the mitotic spindle and the cytoplasmic microtubules (MTs), both of which generate forces in order to faithfully segregate chromosomes, remain separated by the nuclear envelope throughout the cell cycle. Kar3, the yeast kinesin-14, has distinct functions on MTs in each compartment. Here, we show that two proteins, Cik1 and Vik1, which form heterodimers with Kar3, regulate its localization and function within the cell and along MTs in a cell cycle-dependent manner. Using a yeast MT dynamics reconstitution assay in lysates from cell cycle-synchronized cells, we found that Kar3Vik1 induces MT catastrophes in S phase and metaphase and limits MT polymerization in G1 and anaphase. In contrast, Kar3Cik1 promotes catastrophes and pauses in G1, while increasing catastrophes in metaphase and anaphase. Adapting this assay to track MT motor protein motility, we observed that Cik1 is necessary for Kar3's ability to track MT plus-ends in S phase and metaphase, but, surprisingly, not during anaphase. These experiments demonstrate how the binding partners of Kar3 modulate its diverse functions both spatially and temporally.

Keywords:  Cell cycle; Kar3; Kinesin-14; Microtubules; Reconstitution

DOI:  https://doi.org/10.1242/jcs.260621
Mol Cell. 2023 May 18. pii: S1097-2765(23)00284-8. [Epub ahead of print]83(10): 1549-1551

Lactate fuels mitosis.

Xiaoming Dai, Wenyi Wei.

Cell cycle and metabolism are intimately intertwined, but how metabolites directly regulate cell-cycle machinery remains elusive. Liu et al.1 reveal that glycolysis end-product lactate directly binds and inhibits the SUMO protease SENP1 to govern the E3 ligase activity of the anaphase-promoting complex, leading to efficient mitotic exit in proliferative cells.

DOI: https://doi.org/10.1016/j.molcel.2023.04.013
Proc Natl Acad Sci U S A. 2023 05 23. 120(21): e2300877120

Disruption of the standard kinetochore in holocentric Cuscuta species.

Pavel Neumann, Ludmila Oliveira, Tae-Soo Jang, Petr Novák, Andrea Koblížková, Veit Schubert, Andreas Houben, Jiří Macas.

  The segregation of chromosomes depends on the centromere. Most species are monocentric, with the centromere restricted to a single region per chromosome. In some organisms, the monocentric organization changed to holocentric, in which the centromere activity is distributed over the entire chromosome length. However, the causes and consequences of this transition are poorly understood. Here, we show that the transition in the genus Cuscuta was associated with dramatic changes in the kinetochore, a protein complex that mediates the attachment of chromosomes to microtubules. We found that in holocentric Cuscuta species, the KNL2 genes were lost; the CENP-C, KNL1, and ZWINT1 genes were truncated; the centromeric localization of CENH3, CENP-C, KNL1, MIS12, and NDC80 proteins was disrupted; and the spindle assembly checkpoint (SAC) degenerated. Our results demonstrate that holocentric Cuscuta species lost the ability to form a standard kinetochore and do not employ SAC to control the attachment of microtubules to chromosomes.

Keywords:  Cuscuta; centromere; holocentric; kinetochore; monocentric

DOI:  https://doi.org/10.1073/pnas.2300877120
bioRxiv. 2023 May 06. pii: 2023.05.05.539649. [Epub ahead of print]

Mitotic spindle positioning protein (MISP) is an actin bundler that senses ADP-actin and binds near the pointed ends of filaments.

E Angelo Morales, Matthew J Tyska.

Actin bundling proteins crosslink filaments into polarized structures that shape and support membrane protrusions including filopodia, microvilli, and stereocilia. In the case of epithelial microvilli, mitotic spindle positioning protein (MISP) is an actin bundler that localizes specifically to the basal rootlets, where the pointed ends of core bundle filaments converge. Previous studies established that MISP is prevented from binding more distal segments of the core bundle by competition with other actin binding proteins. Yet whether MISP holds a preference for binding directly to rootlet actin remains an open question. Using in vitro TIRF microscopy assays, we found that MISP exhibits a clear binding preference for filaments enriched in ADP-actin monomers. Consistent with this, assays with actively growing actin filaments revealed that MISP binds at or near their pointed ends. Moreover, although substrate attached MISP assembles filament bundles in parallel and antiparallel configurations, in solution MISP assembles parallel bundles consisting of multiple filaments exhibiting uniform polarity. These discoveries highlight nucleotide state sensing as a mechanism for sorting actin bundlers along filaments and driving their accumulation near filament ends. Such localized binding might drive parallel bundle formation and/or locally modulate bundle mechanical properties in microvilli and related protrusions.

DOI: https://doi.org/10.1101/2023.05.05.539649
J Biol Chem. 2023 May 16. pii: S0021-9258(23)01862-8. [Epub ahead of print] 104834

Disruption of CDK7 signaling leads to catastrophic chromosomal instability coupled with a loss of condensin-mediated chromatin compaction.

Katrina M Piemonte, Bryan M Webb, Jessica R Bobbitt, Parth R Majmudar, Leslie Cuellar-Vite, Benjamin L Bryson, Nicholas C Latina, Darcie D Seachrist, Ruth A Keri.

  Chromatin organization is highly dynamic and modulates DNA replication, transcription and chromosome segregation. Condensin is essential for chromosome assembly during mitosis and meiosis, as well as maintenance of chromosome structure during interphase. While it is well established that sustained condensin expression is necessary to ensure chromosome stability, the mechanisms that control its expression are not yet known. Herein, we report that disruption of Cyclin-Dependent Kinase 7 (CDK7), the core catalytic subunit of CDK-Activating Kinase (CAK) leads to reduced transcription of several condensin subunits, including structural maintenance of chromosomes 2 (SMC2). Live and static microscopy revealed that disruption of CDK7 signaling prolongs mitosis and induces chromatin bridge formation, DNA double-strand breaks, and abnormal nuclear features, all of which are indicative of mitotic catastrophe and chromosome instability. Affirming the importance of condensin regulation by CDK7, genetic suppression of SMC2, a core subunit of this complex, phenocopies CDK7 inhibition. Moreover, analysis of genome-wide chromatin conformation using Hi-C revealed that sustained activity of CDK7 is necessary to maintain chromatin sub-looping, a function that is ascribed to condensin. Notably, the regulation of condensin subunit gene expression is independent of super-enhancers. Together, these studies reveal a new role for CDK7 in sustaining chromatin configuration by ensuring the expression of condensin genes, including SMC2.

Keywords:  CDK7; CT7001; Cyclin dependent kinase 7; SMC2; THZ1; TNBC; chromosomal instability; condensin; mitosis; mitotic catastrophe; triple negative breast cancer

DOI:  https://doi.org/10.1016/j.jbc.2023.104834
Cell Rep. 2023 May 17. pii: S2211-1247(23)00542-9. [Epub ahead of print]42(5): 112531

MYO10 regulates genome stability and cancer inflammation through mediating mitosis.

Franklin Mayca Pozo, Xinran Geng, Masaru Miyagi, Amanda L Amin, Alex Y Huang, Youwei Zhang.

  Genomic instability can promote inflammation and tumor development. Previous research revealed an unexpected layer of regulation of genomic instability by a cytoplasmic protein MYO10; however, the underlying mechanism remained unclear. Here, we report a protein stability-mediated mitotic regulation of MYO10 in controlling genome stability. We characterized a degron motif and phosphorylation residues in the degron that mediate β-TrCP1-dependent MYO10 degradation. The level of phosphorylated MYO10 protein transiently increases during mitosis, which is accompanied by a spatiotemporal cellular localization change first accumulating at the centrosome then at the midbody. Depletion of MYO10 or expression of MYO10 degron mutants, including those found in cancer patients, disrupts mitosis, increases genomic instability and inflammation, and promotes tumor growth; however, they also increase the sensitivity of cancer cells to Taxol. Our studies demonstrate a critical role of MYO10 in mitosis progression, through which it regulates genome stability, cancer growth, and cellular response to mitotic toxins.

Keywords:  CP: Cancer; CP: Molecular biology; MYO10; Taxol sensitivity; cancer inflammation; cancer mutation; degron; genomic instability; phosphorylation; protein degradation

DOI:  https://doi.org/10.1016/j.celrep.2023.112531
Neuro Oncol. 2023 Apr 26. pii: noad082. [Epub ahead of print]

Mitogen-Induced Defective Mitosis Transforms Neural Progenitor Cells.

Hiba K Omairi, Cameron J Grisdale, Mathieu Meode, Alexandra K Bohm, Sophie Black, Nancy J Adam, Cassidy P Chapman, Tatiana Maroilley, John J Kelly, Maja Tarailo-Graovac, Steven J M Jones, Michael D Blough, J Gregory Cairncross.

   BACKGROUND: Chromosome instability (CIN) with recurrent copy number alterations is a feature of many solid tumors, including glioblastoma (GBM), yet the genes that regulate cell division are rarely mutated in cancers. Here, we show that the brain-abundant mitogen, platelet-derived growth factor-A (PDGFA) fails to induce the expression of kinetochore and spindle assembly checkpoint genes leading to defective mitosis in neural progenitor cells (NPCs).
METHODS: Using a recently reported in vitro model of the initiation of high-grade gliomas from murine NPCs, we investigated the immediate effects of PDGFA exposure on the nuclear and mitotic phenotypes and patterns of gene and protein expression in NPCs, a putative GBM cell of origin.
RESULTS: NPCs divided abnormally in defined media containing PDGFA with P53-dependent effects. In wild type cells, defective mitosis was associated with P53 activation and cell death, but in some null cells defective mitosis was tolerated. Surviving cells had unstable genomes and proliferated in the presence of PDGFA accumulating random and clonal chromosomal rearrangements. The outcome of this process was a population of tumorigenic NPCs with recurrent gains and losses of chromosomal regions that were syntenic to those recurrently gained and lost in human GBM. By stimulating proliferation without setting the stage for successful mitosis, PDGFA transformed NPCs lacking P53 function.
CONCLUSION: Our work describes a mechanism of transformation of NPCs by a brain-associated mitogen, raising the possibility that the unique genomic architecture of GBM is an adaptation to defective mitosis that ensures the survival of affected cells.

Keywords:  GBM; P53; PDGFA; kinetochore; mitosis

DOI:  https://doi.org/10.1093/neuonc/noad082