bims-micesi 2024-08-04 papers

bims-micesi

Biomed News

on Mitotic cell signalling

Issue of 2024–08–04
eleven papers selected by
Valentina Piano, Uniklinik Köln

Spindle assembly checkpoint-dependent mitotic delay is required for cell division in absence of centrosomes.
The Molecular Mechanism of Aurora-B Regulating Kinetochore-Microtubule Attachment in Mitosis and Oocyte Meiosis.
Human CKAP2L shows a cell cycle-dependent expression pattern and exhibits microtubule-stabilizing properties.
Eg5 UFMylation promotes spindle organization during mitosis.
Distinct roles of spindle checkpoint proteins in meiosis.
Meiosis-specific decoupling of the pericentromere from the kinetochore.
Zygotic spindle orientation defines cleavage pattern and nuclear status of human embryos.
mTORC1 activity oscillates throughout the cell cycle, promoting mitotic entry and differentially influencing autophagy induction.
Propylparaben exposure impairs G2/M and metaphase-anaphase transition during mouse oocyte maturation.
Chromosome components central to cell division evolve rapidly.
Ultra-high static magnetic fields altered the embryonic division and development in Caenorhabditis elegans via multipolar spindles.

Elife. 2024 Aug 02. pii: RP84875. [Epub ahead of print]12

Spindle assembly checkpoint-dependent mitotic delay is required for cell division in absence of centrosomes.

K C Farrell, Jennifer T Wang, Tim Stearns.

  The spindle assembly checkpoint (SAC) temporally regulates mitosis by preventing progression from metaphase to anaphase until all chromosomes are correctly attached to the mitotic spindle. Centrosomes refine the spatial organization of the mitotic spindle at the spindle poles. However, centrosome loss leads to elongated mitosis, suggesting that centrosomes also inform the temporal organization of mitosis in mammalian cells. Here, we find that the mitotic delay in acentrosomal cells is enforced by the SAC in a MPS1-dependent manner, and that a SAC-dependent mitotic delay is required for bipolar cell division to occur in acentrosomal cells. Although acentrosomal cells become polyploid, polyploidy is not sufficient to cause dependency on a SAC-mediated delay to complete cell division. Rather, the division failure in absence of MPS1 activity results from mitotic exit occurring before acentrosomal spindles can become bipolar. Furthermore, prevention of centrosome separation suffices to make cell division reliant on a SAC-dependent mitotic delay. Thus, centrosomes and their definition of two spindle poles early in mitosis provide a 'timely two-ness' that allows cell division to occur in absence of a SAC-dependent mitotic delay.

Keywords:  cell biology; centrosome; human; mitosis; spindle; spindle assembly checkpoint

DOI:  https://doi.org/10.7554/eLife.84875
Cytogenet Genome Res. 2024 Jul 27.

The Molecular Mechanism of Aurora-B Regulating Kinetochore-Microtubule Attachment in Mitosis and Oocyte Meiosis.

Shanshan Chen, Qiqi Sun, Bo Yao, Yanping Ren.

BACKGROUND: Aurora kinase B (Aurora-B), a member of the chromosomal passenger complex (CPC), is involved in correcting kinetochore-microtubule (KT-MT) attachment errors and regulating sister chromatid condensation and cytoplasmic division during mitosis.
SUMMARY: However, few reviews have discussed its mechanism in oocyte meiosis and the differences between its role in mitosis and meiosis. Therefore, in this review, we summarize the localization, recruitment, activation, and functions of Aurora-B in mitosis and oocyte meiosis. The accurate regulation of Aurora-B is essential for ensuring accurate chromosomal segregation and correct KT-MT attachments. Aurora-B regulates the stability of KT-MT attachments by competing with cyclin-dependent kinase 1 (CDK1) to control the phosphorylation of the SILK and RVSF motifs on kinetochore scaffold 1 and by competing with protein phosphatase 1 (PP1) to influence the phosphorylation of NDC80 which is the substrate of Aurora-B. In addition, Aurora-B regulates the spindle assembly checkpoint (SAC) by promoting the recruitment and activation of mitotic arrest deficient 2 (MAD2).
KEY MESSAGES: This review provides a theoretical foundation for elucidating the mechanism of cell division and understanding oocyte chromosomal aneuploidy.

DOI: https://doi.org/10.1159/000540588
FEBS Open Bio. 2024 Jul 28.

Human CKAP2L shows a cell cycle-dependent expression pattern and exhibits microtubule-stabilizing properties.

Hyerim Kwon, Jonathan Y Joh, Kyung U Hong.

  Cytoskeleton-associated protein 2-like (CKAP2L) is a paralogue of cytoskeleton-associated protein 2 (CKAP2). We characterized the expression pattern, subcellular localization, and microtubule-stabilizing properties of human CKAP2L. The levels of both CKAP2L transcript and protein were cell cycle phase-dependent, peaking during the G2/M phase and relatively high in certain human tissues, including testis, intestine, and spleen. CKAP2L protein was detectable in all human cancer cell lines we tested. CKAP2L localized to the mitotic spindle apparatus during mitosis, as reported previously. During interphase, however, CKAP2L localized mainly to the nucleus. Ectopic overexpression of CKAP2L resulted in 'microtubule bundling', and, consequently, an elevated CKAP2L level led to prolonged mitosis. These findings support the mitotic role of CKAP2L during the human cell cycle.

Keywords:  cell cycle; cytoskeleton‐associated protein 2; cytoskeleton‐associated protein 2‐like; microtubule; mitosis; mitotic spindle

DOI:  https://doi.org/10.1002/2211-5463.13864
Cell Death Dis. 2024 Jul 31. 15(7): 544

Eg5 UFMylation promotes spindle organization during mitosis.

Guangxu Li, Yuanjiang Huang, Wenbo Han, Liyi Wei, Hongjing Huang, Yingbao Zhu, Qiao Xiao, Zujia Wang, Wen Huang, Ranhui Duan.

UFMylation is a highly conserved ubiquitin-like post-translational modification that catalyzes the covalent linkage of UFM1 to its target proteins. This modification plays a critical role in the maintenance of endoplasmic reticulum proteostasis, DNA damage response, autophagy, and transcriptional regulation. Mutations in UFM1, as well as in its specific E1 enzyme UBA5 and E2 enzyme UFC1, have been genetically linked to microcephaly. Our previous research unveiled the important role of UFMylation in regulating mitosis. However, the underlying mechanisms have remained unclear due to the limited identification of substrates. In this study, we identified Eg5, a motor protein crucial for mitotic spindle assembly and maintenance, as a novel substrate for UFMylation and identified Lys564 as the crucial UFMylation site. UFMylation did not alter its transcriptional level, phosphorylation level, or protein stability, but affected the mono-ubiquitination of Eg5. During mitosis, Eg5 and UFM1 co-localize at the centrosome and spindle apparatus, and defective UFMylation leads to diminished spindle localization of Eg5. Notably, the UFMylation-defective Eg5 mutant (K564R) exhibited shorter spindles, metaphase arrest, spindle checkpoint activation, and a failure of cell division in HeLa cells. Overall, Eg5 UFMylation is essential for proper spindle organization, mitotic progression, and cell proliferation.

DOI: https://doi.org/10.1038/s41419-024-06934-w
Curr Biol. 2024 Jul 24. pii: S0960-9822(24)00928-X. [Epub ahead of print]

Distinct roles of spindle checkpoint proteins in meiosis.

Anuradha Mukherjee, Christos Spanos, Adele L Marston.

  Gametes are produced via meiosis, a specialized cell division associated with frequent errors that cause birth defects and infertility. Uniquely in meiosis I, homologous chromosomes segregate to opposite poles, usually requiring their linkage by chiasmata, the products of crossover recombination.1 The spindle checkpoint delays cell-cycle progression until all chromosomes are properly attached to microtubules,2 but the steps leading to the capture and alignment of chromosomes on the meiosis I spindle remain poorly understood. In budding yeast meiosis I, Mad2 and Mad3BUBR1 are equally important for spindle checkpoint delay, but biorientation of homologs on the meiosis I spindle requires Mad2, but not Mad3BUBR1.3,4 Here we reveal the distinct functions of Mad2 and Mad3BUBR1 in meiosis I chromosome segregation. Mad2 promotes the prophase to metaphase I transition, while Mad3BUBR1 associates with the TOGL1 domain of Stu1CLASP, a conserved plus-end microtubule protein that is important for chromosome capture onto the spindle. Homologous chromosome pairs that are proficient in crossover formation but fail to biorient rely on Mad3BUBR1-Stu1CLASP to ensure their efficient attachment to microtubules and segregation during meiosis I. Furthermore, we show that Mad3BUBR1-Stu1CLASP are essential to rescue the segregation of mini-chromosomes lacking crossovers. Our findings define a new pathway ensuring microtubule-dependent chromosome capture and demonstrate that spindle checkpoint proteins safeguard the fidelity of chromosome segregation both by actively promoting chromosome alignment and by delaying cell-cycle progression until this has occurred.

Keywords:  Mad2; Mad3/BubR1; Stu1/CLASP; achiasmate segregation; kinetochore; meiosis; meiotic timing; microtubule; spindle checkpoint

DOI:  https://doi.org/10.1016/j.cub.2024.07.025
bioRxiv. 2024 Jul 22. pii: 2024.07.21.604490. [Epub ahead of print]

Meiosis-specific decoupling of the pericentromere from the kinetochore.

Bo Pan, Melania Bruno, Todd S Macfarlan, Takashi Akera.

The primary constriction site of the M-phase chromosome is an established marker for the kinetochore position, often used to determine the karyotype of each species. Underlying this observation is the concept that the kinetochore is spatially linked with the pericentromere where sister-chromatids are most tightly cohered. Here, we found an unconventional pericentromere specification with sister chromatids mainly cohered at a chromosome end, spatially separated from the kinetochore in Peromyscus mouse oocytes. This distal locus enriched cohesin protectors, such as the Chromosomal Passenger Complex (CPC) and PP2A, at a higher level compared to its centromere/kinetochore region, acting as the primary site for sister-chromatid cohesion. Chromosomes with the distal cohesion site exhibited enhanced cohesin protection at anaphase I compared to those without it, implying that these distal cohesion sites may have evolved to ensure sister-chromatid cohesion during meiosis. In contrast, mitotic cells enriched CPC only near the kinetochore and the distal locus was not cohered between sister chromatids, suggesting a meiosis-specific mechanism to protect cohesin at this distal locus. We found that this distal locus corresponds to an additional centromeric satellite block, located far apart from the centromeric satellite block that builds the kinetochore. Several Peromyscus species carry chromosomes with two such centromeric satellite blocks. Analyses on three Peromyscus species revealed that the internal satellite consistently assembles the kinetochore in both mitosis and meiosis, whereas the distal satellite selectively enriches cohesin protectors in meiosis to promote sister-chromatid cohesion at that site. Thus, our study demonstrates that pericentromere specification is remarkably flexible and can control chromosome segregation in a cell-type and context dependent manner.

DOI: https://doi.org/10.1101/2024.07.21.604490
Nat Commun. 2024 Jul 29. 15(1): 6369

Zygotic spindle orientation defines cleavage pattern and nuclear status of human embryos.

Volodymyr Porokh, Drahomíra Kyjovská, Martina Martonová, Tereza Klenková, Pavel Otevřel, Soňa Kloudová, Zuzana Holubcová.

The first embryonic division represents a starting point for the development of a new individual. In many species, tight control over the first embryonic division ensures its accuracy. However, the first division in humans is often erroneous and can impair embryo development. To delineate the spatiotemporal organization of the first mitotic division typical for normal human embryo development, we systematically analyzed a unique timelapse dataset of 300 IVF embryos that developed into healthy newborns. The zygotic division pattern of these best-quality embryos was compared to their siblings that failed to implant or arrested during cleavage stage. We show that division at the right angle to the juxtaposed pronuclei is preferential and supports faithful zygotic division. Alternative configurations of the first mitosis are associated with reduced clustering of nucleoli and multinucleation at the 2-cell stage, which are more common in women of advanced age. Collectively, these data imply that orientation of the first division predisposes human embryos to genetic (in)stability and may contribute to aneuploidy and age-related infertility.

DOI: https://doi.org/10.1038/s41467-024-50732-z
Cell Rep. 2024 Jul 26. pii: S2211-1247(24)00872-6. [Epub ahead of print]43(8): 114543

mTORC1 activity oscillates throughout the cell cycle, promoting mitotic entry and differentially influencing autophagy induction.

Jay N Joshi, Ariel D Lerner, Frank Scallo, Alexandra N Grumet, Paul Matteson, James H Millonig, Alexander J Valvezan.

  Mechanistic Target of Rapamycin Complex 1 (mTORC1) is a master metabolic regulator that is active in nearly all proliferating eukaryotic cells; however, it is unclear whether mTORC1 activity changes throughout the cell cycle. We find that mTORC1 activity oscillates from lowest in mitosis/G1 to highest in S/G2. The interphase oscillation is mediated through the TSC complex but is independent of major known regulatory inputs, including Akt and Mek/Erk signaling. By contrast, suppression of mTORC1 activity in mitosis does not require the TSC complex. mTORC1 has long been known to promote progression through G1. We find that mTORC1 also promotes progression through S and G2 and is important for satisfying the Chk1/Wee1-dependent G2/M checkpoint to allow entry into mitosis. We also find that low mTORC1 activity in G1 sensitizes cells to autophagy induction in response to partial mTORC1 inhibition or reduced nutrient levels. Together, these findings demonstrate that mTORC1 is differentially regulated throughout the cell cycle, with important phase-specific consequences for proliferating cells.

Keywords:  CDK1; CP: Cell biology; G2/M checkpoint; TSC complex; TSC2; autophagy; cell cycle; mTOR; mTORC1; mitosis

DOI:  https://doi.org/10.1016/j.celrep.2024.114543
Ecotoxicol Environ Saf. 2024 Jul 30. pii: S0147-6513(24)00874-1. [Epub ahead of print]283 116798

Propylparaben exposure impairs G2/M and metaphase-anaphase transition during mouse oocyte maturation.

Zhen-Nan Pan, Li-Li Zhuang, Hui-Shan Zhao, Shu-Yuan Yin, Min Chu, Xiao-Yan Liu, Hong-Chu Bao.

  Propylparaben (PrPB) is a known endocrine disrupting chemicals that is widely applied as preservative in pharmaceuticals, food and cosmetics. PrPB has been detected in human urine samples and human serum and has been proven to cause functional decline in reproduction. However, the direct effects of PrPB on mammalian oocyte are still unknown. Here, we demonstrationed that exposure to PrPB disturbed mouse oocyte maturation in vitro, causing meiotic resumption arrest and first polar body extrusion failure. Our results indicated that 600 μM PrPB reduced the rate of oocyte germinal vesicle breakdown (GVBD). Further research revealed that PrPB caused mitochondrial dysfunction and oxidative stress, which led to oocyte DNA damage. This damage further disturbed the activity of the maturation promoting factor (MPF) complex Cyclin B1/ Cyclin-dependent kinase 1 (CDK1) and induced G2/M arrest. Subsequent experiments revealed that PrPB exposure can lead to spindle morphology disorder and chromosome misalignment due to unstable microtubules. In addition, PrPB adversely affected the attachment between microtubules and kinetochore, resulting in persistent activation of BUB3 amd BubR1, which are two spindle-assembly checkpoint (SAC) protein. Taken together, our studies indicated that PrPB damaged mouse oocyte maturation via disrupting MPF related G2/M transition and SAC depended metaphase-anaphase transition.

Keywords:  G2/M transition; Propylparaben; meiosis; metaphase-anaphase transition; oocyte; spindle

DOI:  https://doi.org/10.1016/j.ecoenv.2024.116798
Nature. 2024 Aug 02.

Chromosome components central to cell division evolve rapidly.



Keywords:  Cell biology; DNA sequencing; Genomics

DOI:  https://doi.org/10.1038/d41586-024-02523-1
J Adv Res. 2024 Jul 30. pii: S2090-1232(24)00316-3. [Epub ahead of print]

Ultra-high static magnetic fields altered the embryonic division and development in Caenorhabditis elegans via multipolar spindles.

Lei Cheng, Mudi Wang, Baolin Yang, Yang Li, Tong Wang, Chuanying Xi, Yuyan Han, Ze Wang, Yanwen Fang, Min Wei, Hua Du, An Xu.

   INTRODUCTION: Ultra-high static magnetic fields (SMF) have unique advantages in improving medical and academic research. However, the research on the early embryo exposure of ultrahigh SMF is minimal, extensive exploration is indispensable in living organisms.
OBJECTIVES: The present study was aimed to study the effects of ultra-high SMF on the early embryonic division and development of Caenorhabditis elegans (C. elegans).
METHODS: Early adult parents containing fertilized eggs in vivo were exposed to SMF at intensities ranging from 4 T to 27 T. The number of mitotic cells in the reproductive glands of the P0 worms, early embryonic cell spindle localization, embryo hatching and the reproductive as well as developmental indicators of F1 and F2 nematodes were examined as endpoints.
RESULTS: Our results indicated that ultra-high SMF has no obvious effect on the germ cell cycle, while 14 T and 27 T SMF significantly increased the proportion of multi-polar spindle formation in early embryonic cells, and reduced the developmental rate and lifespan of C. elegans exposure at the embryonic stage. Spindle abnormalities of early embryonic cells, as well as the down-regulation of genes related to asymmetric embryonic division and the abnormal expression of the non-muscle myosin NMY-2 in the division grooves play a critical role in the slowing down of embryonic development induced by ultra-high SMF.
CONCLUSIONS: This study provided novel information and a new sight for evaluating the biosafety assessment by exposure to ultra high SMF at the early embryonic stage in vivo.

Keywords:  C. elegans; Development; Embryonic division; Spindle abnormalities; Ultra high SMF

DOI:  https://doi.org/10.1016/j.jare.2024.07.032