bims-micesi 2023-11-26 papers

bims-micesi

Biomed News

on Mitotic cell signalling

Issue of 2023–11–26
eight papers selected by
Valentina Piano, Uniklinik Köln

RZZ-Spindly and CENP-E form an integrated platform to recruit dynein to the kinetochore corona.
An interaction hub on Ndc80 complex facilitates dynamic recruitment of Mps1 to yeast kinetochores to promote accurate chromosome segregation.
Orientation-Independent-DIC imaging reveals that a transient rise in macromolecular crowding contributes to mitotic chromosome condensation.
Branched microtubule nucleation and dynein transport organize RanGTP asters in Xenopus laevis egg extract.
Unconventional roles of chromatin remodelers and long non-coding RNAs in cell division.
Cytoplasm mechanics and cellular organization.
A homozygous variant in INTS11 links mitosis and neurogenesis defects to a severe neurodevelopmental disorder.
Multifunctional Cationic Hyperbranched Polyaminoglycosides that Target Multiple Mediators for Severe Abdominal Trauma Management.

EMBO J. 2023 Nov 20. e114838

RZZ-Spindly and CENP-E form an integrated platform to recruit dynein to the kinetochore corona.

Verena Cmentowski, Giuseppe Ciossani, Ennio d'Amico, Sabine Wohlgemuth, Mikito Owa, Brian Dynlacht, Andrea Musacchio.

  Chromosome biorientation on the mitotic spindle is prerequisite to errorless genome inheritance. CENP-E (kinesin-7) and dynein-dynactin (DD), microtubule motors with opposite polarity, promote biorientation from the kinetochore corona, a polymeric structure whose assembly requires MPS1 kinase. The corona's building block consists of ROD, Zwilch, ZW10, and the DD adaptor Spindly (RZZS). How CENP-E and DD are scaffolded and mutually coordinated in the corona remains unclear. Here, we show that when corona assembly is prevented through MPS1 inhibition, CENP-E is absolutely required to retain RZZS at kinetochores. An RZZS phosphomimetic mutant bypasses this requirement, demonstrating the existence of a second receptor for polymeric RZZS. With active MPS1, CENP-E is dispensable for corona expansion, but strictly required for physiological kinetochore accumulation of DD. Thus, we identify the corona as an integrated scaffold where CENP-E kinesin controls DD kinetochore loading for coordinated bidirectional transport of chromosome cargo.

Keywords:  CENP-E; centromere; kinetochore fibrous corona; mitosis; spindle assembly checkpoint

DOI:  https://doi.org/10.15252/embj.2023114838
bioRxiv. 2023 Nov 07. pii: 2023.11.07.566082. [Epub ahead of print]

An interaction hub on Ndc80 complex facilitates dynamic recruitment of Mps1 to yeast kinetochores to promote accurate chromosome segregation.

Emily J Parnell, Erin Jenson, Matthew P Miller.

Accurate chromosome segregation relies on kinetochores carrying out multiple functions, including establishing and maintaining microtubule attachments, forming precise bioriented attachments between sister chromatids, and activating the spindle assembly checkpoint. Central to these processes is the highly conserved Ndc80 complex. This kinetochore subcomplex interacts directly with microtubules, but also serves as a critical platform for recruiting kinetochore-associated factors and as a key substrate for error correction kinases. The precise manner in which these kinetochore factors interact, and regulate each other's function, remains unknown - considerably hindering our understanding of how Ndc80 complex-dependent processes function together to orchestrate accurate chromosome segregation. Here, we aimed to uncover the role of Nuf2's CH domain, a component of the Ndc80 complex, in ensuring accurate chromosome segregation. Through extensive mutational analysis, we identified a conserved "interaction hub" comprising two segments in Nuf2's CH domain, forming the binding site for Mps1 within the yeast Ndc80 complex. Intriguingly, the interaction between Mps1 and the Ndc80 complex seems to be subject to regulation by competitive binding with other factors. Mutants disrupting this interaction hub exhibit defects in spindle assembly checkpoint function and severe chromosome segregation errors. Significantly, specifically restoring Mps1-Ndc80 complex association rescues these defects. Our findings shed light on the intricate regulation of Ndc80 complex-dependent functions and highlight the essential role of Mps1 in kinetochore biorientation and accurate chromosome segregation.

DOI: https://doi.org/10.1101/2023.11.07.566082
bioRxiv. 2023 Nov 11. pii: 2023.11.11.566679. [Epub ahead of print]

Orientation-Independent-DIC imaging reveals that a transient rise in macromolecular crowding contributes to mitotic chromosome condensation.

Shiori Iida, Satoru Ide, Sachiko Tamura, Tomomi Tani, Tatsuhiko Goto, Michael Shribak, Kazuhiro Maeshima.

Genomic information must be faithfully transmitted into two daughter cells during cell division. To ensure the transmission process, interphase chromatin is further condensed into mitotic chromosomes. Although protein factors like condensins and topoisomerase IIα are involved in the assembly of mitotic chromosomes, the physical bases of the condensation process remain unclear. Macromolecular crowding/depletion force, an effective attractive force that arises between large structures in crowded environments around chromosomes, may contribute to the condensation process. To approach this issue, we investigated the "chromosome milieu" during mitosis of living human cells using orientation-independent-differential interference contrast (OI-DIC) module combined with a confocal laser scanning microscope, which is capable of precisely mapping optical path differences and estimating molecular densities. We found that the molecular density surrounding chromosomes increased with the progression from prometaphase to anaphase, concurring with chromosome condensation. However, the molecular density went down in telophase, when chromosome decondensation began. Changes in the molecular density around chromosomes by hypotonic or hypertonic treatment consistently altered the condensation levels of chromosomes. In vitro , native chromatin was converted into liquid droplets of chromatin in the presence of cations and a macromolecular crowder. Additional crowder made the chromatin droplets stiffer and more solid-like, with further condensation. These results suggest that a transient rise in macromolecular crowding (proteins and RNAs), likely triggered by the relocation of macromolecules via nuclear envelope breakdown and also by a subsequent decrease in cell-volumes, contributes to mitotic chromosome condensation, shedding light on a new aspect of the condensation mechanism in living human cells.
Significance Statement: Mitotic chromosome condensation is an essential process to transmit replicated chromosomes into two daughter cells during cell division. To study the underlying physical principles of this process, we focused on macromolecular crowding/depletion force, which is a force that attracts large structures in crowded cell environments. Using newly developed special light microscopy, which can image the molecular density of cellular environments, we found that crowding around chromosomes increases during cell division. In vitro , higher concentrations of macromolecules condense chromatin and make it stiffer and more solid-like. Our results suggest that the rise in macromolecular crowding renders chromosomes more rigid, ensuring accurate chromosome transmission during cell division.

DOI: https://doi.org/10.1101/2023.11.11.566679
Mol Biol Cell. 2023 Nov 22. mbcE23100407

Branched microtubule nucleation and dynein transport organize RanGTP asters in Xenopus laevis egg extract.

Jacopo Scrofani, Felix Ruhnow, Wei-Xiang Chew, Davide Normanno, Francois Nedelec, Thomas Surrey, Isabelle Vernos.

Chromosome segregation relies on the correct assembly of a bipolar spindle. Spindle pole self-organization requires dynein-dependent microtubule transport along other microtubules. However, during M-phase RanGTP triggers microtubule nucleation and branching generating polarized arrays with non-astral organization in which microtubule minus ends are linked to the sides of other microtubules. This raises the question of how branched-microtubule nucleation and dynein-mediated transport cooperate to organize the spindle poles. Here, we used RanGTP-dependent microtubule aster formation in Xenopus laevis egg extract to study the interplay between these two seemingly conflicting organizing principles. Using temporally controlled perturbations of microtubule nucleation and dynein activity, we found that branched microtubules are not static but instead dynamically redistribute over time as poles self-organize. Our experimental data together with computer simulations suggest a model where dynein together with dynactin and NuMA directly pulls and move branched microtubule minus ends towards other microtubule minus ends.

DOI: https://doi.org/10.1091/mbc.E23-10-0407
Cell Mol Life Sci. 2023 Nov 20. 80(12): 365

Unconventional roles of chromatin remodelers and long non-coding RNAs in cell division.

Yuri Prozzillo, Maria Virginia Santopietro, Giovanni Messina, Patrizio Dimitri.

  The aim of this review article is to focus on the unconventional roles of epigenetic players (chromatin remodelers and long non-coding RNAs) in cell division, beyond their well-characterized functions in chromatin regulation during cell differentiation and development. In the last two decades, diverse experimental evidence has shown that subunits of SRCAP and p400/TIP60 chromatin remodeling complexes in humans relocate from interphase nuclei to centrosomes, spindle or midbody, with their depletion yielding an array of aberrant outcomes of mitosis and cytokinesis. Remarkably, this behavior is shared by orthologous subunits of the Drosophila melanogaster DOM/TIP60 complex, despite fruit flies and humans diverged over 700 million years ago. In short, the available data support the view that subunits of these complexes are a new class of moonlighting proteins, in that they lead a "double life": during the interphase, they function in chromatin regulation within the nucleus, but as the cell progresses through mitosis, they interact with established mitotic factors, thus becoming integral components of the cell division apparatus. By doing so, they contribute to ensuring the correct distribution of chromosomes in the two daughter cells and, when dysfunctional, can cause genomic instability, a condition that can trigger tumorigenesis and developmental diseases. Research over the past few years has unveiled a major contribution of long non-coding RNAs (lncRNAs) in the epigenetics regulation of gene expression which also impacts on cell division control. Here, we focus on possible structural roles of lncRNAs in the execution of cytokinesis: in particular, we suggest that specific classes of lncRNAs relocate to the midbody to form an architectural scaffold ensuring its proper assembly and function during abscission. Drawing attention to experimental evidence for non-canonical extranuclear roles of chromatin factors and lncRNAs has direct implications on important and novel aspects concerning both the epigenetic regulation and the evolutionary dynamics of cell division with a significant impact on differentiation, development, and diseases.

Keywords:  Chromatin remodeling; Cytokinesis; Midbody (MB); Mitosis; Spindle

DOI:  https://doi.org/10.1007/s00018-023-04949-8
Curr Opin Cell Biol. 2023 Nov 16. pii: S0955-0674(23)00127-8. [Epub ahead of print]85 102278

Cytoplasm mechanics and cellular organization.

María Isabel Arjona, Javad Najafi, Nicolas Minc.

  As cells organize spatially or divide, they translocate many micron-scale organelles in their cytoplasm. These include endomembrane vesicles, nuclei, microtubule asters, mitotic spindles, or chromosomes. Organelle motion is powered by cytoskeleton forces but is opposed by viscoelastic forces imparted by the surrounding crowded cytoplasm medium. These resistive forces associated to cytoplasm physcial properties remain generally underappreciated, yet reach significant values to slow down organelle motion or even limit their displacement by springing them back towards their original position. The cytoplasm may also be itself organized in time and space, being for example stiffer or more fluid at certain locations or during particular cell cycle phases. Thus, cytoplasm mechanics may be viewed as a labile module that contributes to organize cells. We here review emerging methods, mechanisms, and concepts to study cytoplasm mechanical properties and their function in organelle positioning, cellular organization and division.

Keywords:  Cell division; Cytoplasm; Mechanobiology; Organelles; Viscoelasticity

DOI:  https://doi.org/10.1016/j.ceb.2023.102278
Cell Rep. 2023 Nov 18. pii: S2211-1247(23)01457-2. [Epub ahead of print]42(12): 113445

A homozygous variant in INTS11 links mitosis and neurogenesis defects to a severe neurodevelopmental disorder.

Hanzhe Kuang, Yunlong Li, Yixuan Wang, Meizhen Shi, Ranhui Duan, Qiao Xiao, Haoyuan She, Yingdi Liu, Qiaowei Liang, Yanling Teng, Miaojin Zhou, Desheng Liang, Zhuo Li, Lingqian Wu.

  The INTS11 endonuclease is crucial in modulating gene expression and has only recently been linked to human neurodevelopmental disorders (NDDs). However, how INTS11 participates in human development and disease remains unclear. Here, we identify a homozygous INTS11 variant in two siblings with a severe NDD. The variant impairs INTS11 catalytic activity, supported by its substrate's accumulation, and causes G2/M arrest in patient cells with length-dependent dysregulation of genes involved in mitosis and neural development, including the NDD gene CDKL5. The mutant knockin (KI) in induced pluripotent stem cells (iPSCs) disturbs their mitotic spindle organization and thus leads to slow proliferation and increased apoptosis, possibly through the decreased neurally functional CDKL5-induced extracellular signal-regulated kinase (ERK) pathway inhibition. The generation of neural progenitor cells (NPCs) from the mutant iPSCs is also delayed, with long transcript loss concerning neurogenesis. Our work reveals a mechanism underlying INTS11 dysfunction-caused human NDD and provides an iPSC model for this disease.

Keywords:  CP: Neuroscience; CP: Stem cell research; INTS11; integrator complex; mitosis; neurodevelopmental disorder; neurogenesis

DOI:  https://doi.org/10.1016/j.celrep.2023.113445
Adv Sci (Weinh). 2023 Nov 23. e2305273

Multifunctional Cationic Hyperbranched Polyaminoglycosides that Target Multiple Mediators for Severe Abdominal Trauma Management.

Yongqiang Xiao, He Fang, Yuefei Zhu, Jie Zhou, Zhanzhan Dai, Hongxia Wang, Zhaofan Xia, Zhaoxu Tu, Kam W Leong.

  Trauma and its associated complications, including dysregulated inflammatory responses, severe infection, and disseminated intravascular coagulation (DIC), continue to pose lethal threats worldwide. Following injury, cell-free nucleic acids (cfNAs), categorized as damage-associated molecular patterns (DAMPs), are released from dying or dead cells, triggering local and systemic inflammatory responses and coagulation abnormalities that worsen disease progression. Harnessing cfNA scavenging strategies with biomaterials has emerged as a promising approach for treating posttrauma systemic inflammation. In this study, the effectiveness of cationic hyperbranched polyaminoglycosides derived from tobramycin (HPT) and disulfide-included HPT (ss-HPT) in scavenging cfNAs to mitigate posttrauma inflammation and hypercoagulation is investigated. Both cationic polymers demonstrate the ability to suppress DAMP-induced toll-like receptor (TLR) activation, inflammatory cytokine secretion, and hypercoagulation by efficiently scavenging cfNAs. Additionally, HPT and ss-HPT exhibit potent antibacterial efficacy attributed to the presence of tobramycin in their chemical composition. Furthermore, HPT and ss-HPT exhibit favorable modulatory effects on inflammation and therapeutic outcomes in a cecal ligation puncture (CLP) mouse abdominal trauma model. Notably, in vivo studies reveal that ss-HPT displayed high accumulation and retention in injured organs of traumatized mice while maintaining a higher biodegradation rate in healthy mice, contrasting with findings for HPT. Thus, functionalized ss-HPT, a bioreducible polyaminoglycoside, holds promise as an effective option to enhance therapeutic outcomes for trauma patients by alleviating posttrauma inflammation and coagulation complications.

Keywords:  abdominal trauma; antibacterial properties; anticoagulation; biodegradable polyaminoglycoside; cfNA scavenging; inflammation modulation

DOI:  https://doi.org/10.1002/advs.202305273