bims-micesi 2023-03-19 papers

bims-micesi

Biomed News

on Mitotic cell signalling

Issue of 2023–03–19
ten papers selected by
Valentina Piano, Uniklinik Köln

Distinct Aurora B pools at the inner centromere and kinetochore have different contributions to meiotic and mitotic chromosome segregation.
Phospho PTEN mediated dephosphorylation of mitotic kinase PLK1 and Aurora Kinase A prevents aneuploidy and preserves genomic stability.
CDC20: a novel therapeutic target in cancer.
Cell biology: Kinetochores nucleate their own microtubules.
Matrin3 regulates mitotic spindle dynamics by controlling alternative splicing of CDC14B.
Triap1 upregulation promotes escape from mitotic-slippage-induced G1 arrest.
Actin-microtubule crosstalk imparts stiffness to the contractile ring in fission yeast.
Structural Optimization and Anticancer Activity of Polo-like Kinase 1 (Plk1) Polo-Box Domain (PBD) Inhibitors and Their Prodrugs.
Short-term molecular consequences of chromosome mis-segregation for genome stability.
The mitotic exit mediated by small GTPase Tem1 is essential for the pathogenicity of Fusarium graminearum.

Mol Biol Cell. 2023 Mar 15. mbcE23010014

Distinct Aurora B pools at the inner centromere and kinetochore have different contributions to meiotic and mitotic chromosome segregation.

Gisela Cairo, Cora Greiwe, Gyu Ik Jung, Cecilia Blengini, Karen Schindler, Soni Lacefield.

Proper chromosome segregation depends on establishment of bioriented kinetochore-microtubule attachments, which often requires multiple rounds of release and reattachment. Aurora B and C kinases phosphorylate kinetochore proteins to release tensionless attachments. Multiple pathways recruit Aurora B/C to the centromere and kinetochore. We studied how these pathways contribute to anaphase onset timing and correction of kinetochore-microtubule attachments in budding yeast meiosis and mitosis. We find that the pool localized by the Bub1/Bub3 pathway sets the normal duration of meiosis and mitosis, in differing ways. Our meiosis data suggests a model that disruption of this pathway leads to PP1 kinetochore localization, which dephosphorylates Cdc20 for premature anaphase onset. For error correction, the Bub1/Bub3 and COMA pathways are individually important in meiosis but compensatory in mitosis. Finally, we find that the haspin and Bub1/3 pathways function together to ensure error correction in mouse oogenesis. Our results suggest that each recruitment pathway localizes spatially distinct kinetochore-localized Aurora B/C pools that function differently between meiosis and mitosis.

DOI: https://doi.org/10.1091/mbc.E23-01-0014
Med Oncol. 2023 Mar 17. 40(4): 119

Phospho PTEN mediated dephosphorylation of mitotic kinase PLK1 and Aurora Kinase A prevents aneuploidy and preserves genomic stability.

Ginia Ghosh, Sandip Misra, Rachayeeta Ray, Sougata Ghosh Chowdhury, Parimal Karmakar.

  PTEN, dual phosphatase tumor suppressor protein, is found to be frequently mutated in various cancers. Post-translational modification of PTEN is important for its sub-cellular localization and catalytic functions. But how these modifications affect cytological damage and aneuploidy is not studied in detail. We focus on the role of phosphatase activity along with C-terminal phosphorylation of PTEN in perspective of cytological damage like micronucleus, nuclear bud, and nuclear bridge formation. Our data suggest that wild-type PTEN, but not phospho-mutant PTEN significantly reduces cytological damage in PTEN null PC3 cells. In case of phosphatase-dead PTEN, cytological damage markers are increased during 24 h recovery after DNA damage. When we use phosphorylation and phosphatase-dead dual mutant PTEN, the extent of different cytological DNA damage parameters are similar to phosphatase-dead PTEN. We also find that both of those activities are essential for maintaining chromosome numbers. PTEN null cells exhibit significantly aberrant γ-tubulin pole formation during metaphase. Interestingly, we observed that p-PTEN localized to spindle poles along with PLK1 and Aurora Kinase A. Further depletion of phosphorylation and phosphatase activity of PTEN increases the expression of p-Aurora Kinase A (T288) and p-PLK1 (T210), compared to cells expressing wild-type PTEN. Again, wild-type PTEN but not phosphorylation-dead mutant is able to physically interact with PLK1 and Aurora Kinase A. Thus, our study suggests that the phosphorylation-dependent interaction of PTEN with PLK1 and Aurora Kinase A causes dephosphorylation of those mitotic kinases and by lowering their hyperphosphorylation status, PTEN prevents aberrant chromosome segregation in metaphase.

Keywords:  Aneuploidy; Aurora Kinase; Micronucleus; PTEN; Polo-like kinase; Spindle pole

DOI:  https://doi.org/10.1007/s12032-023-01985-z
Am J Transl Res. 2023 ;15(2): 678-693

CDC20: a novel therapeutic target in cancer.

Wenning He, Jun Meng.

Cell division cycle protein 20 (Cdc20) is a member of the cell cyclin family. In the early stage of mitosis, it activates the anaphase-promoting complex (APC) and forms the E3 ubiquitin ligase complex APCCdc20, which destroys key regulators of the cell cycle and promotes mitosis. Cdc20 serves as a target for the spindle checkpoint, ensuring proper chromosome segregation. As an oncoprotein, Cdc20 is highly expressed in a variety of malignant tumors, and Cdc20 overexpression is associated with poor prognosis of these tumors. This review aims to dissect the tumorigenic role of Cdc20 in human malignancies and its targeting strategies.

Keywords: Cell division cycle protein 20; E3 ligase; apcin; breast cancer; cancer; hepatocellular carcinoma; osteosarcoma
Curr Biol. 2023 Mar 13. pii: S0960-9822(23)00083-0. [Epub ahead of print]33(5): R187-R190

Cell biology: Kinetochores nucleate their own microtubules.

Fioranna Renda, Alexey Khodjakov.

The origin of microtubules that tether the chromosomes' kinetochores to spindle poles has remained a mystery for several decades. A new study identifies the 'fibrous corona' as an autonomous microtubule nucleation site, and reveals the molecular cascade responsible for this process.

DOI: https://doi.org/10.1016/j.cub.2023.01.049
Cell Rep. 2023 Mar 15. pii: S2211-1247(23)00271-1. [Epub ahead of print]42(3): 112260

Matrin3 regulates mitotic spindle dynamics by controlling alternative splicing of CDC14B.

Bruna R Muys, Roshan L Shrestha, Dimitrios G Anastasakis, Lorinc Pongor, Xiao Ling Li, Ioannis Grammatikakis, Ahsan Polash, Raj Chari, Myriam Gorospe, Curtis C Harris, Mirit I Aladjem, Munira A Basrai, Markus Hafner, Ashish Lal.

  Matrin3 is an RNA-binding protein that regulates diverse RNA-related processes, including mRNA splicing. Although Matrin3 has been intensively studied in neurodegenerative diseases, its function in cancer remains unclear. Here, we report Matrin3-mediated regulation of mitotic spindle dynamics in colorectal cancer (CRC) cells. We comprehensively identified RNAs bound and regulated by Matrin3 in CRC cells and focused on CDC14B, one of the top Matrin3 targets. Matrin3 knockdown results in increased inclusion of an exon containing a premature termination codon in the CDC14B transcript and simultaneous down-regulation of the standard CDC14B transcript. Knockdown of CDC14B phenocopies the defects in mitotic spindle dynamics upon Matrin3 knockdown, and the elongated and misoriented mitotic spindle observed upon Matrin3 knockdown are rescued upon overexpression of CDC14B, suggesting that CDC14B is a key downstream effector of Matrin3. Collectively, these data reveal a role for the Matrin3/CDC14B axis in control of mitotic spindle dynamics.

Keywords:  CP: Cell biology; CP: Molecular biology; RNA-binding proteins; cell cycle; mitotic spindle; nonsense-mediated decay; post-transcriptional gene regulation; splicing

DOI:  https://doi.org/10.1016/j.celrep.2023.112260
Cell Rep. 2023 Mar 13. pii: S2211-1247(23)00226-7. [Epub ahead of print]42(3): 112215

Triap1 upregulation promotes escape from mitotic-slippage-induced G1 arrest.

Mattia Pavani, Elena Chiroli, Camilla Cancrini, Fridolin Gross, Paolo Bonaiuti, Stefano Villa, Fabio Giavazzi, Vittoria Matafora, Angela Bachi, Luca L Fava, Tiziana Lischetti, Andrea Ciliberto.

  Drugs targeting microtubules rely on the mitotic checkpoint to arrest cell proliferation. The prolonged mitotic arrest induced by such drugs is followed by a G1 arrest. Here, we follow for several weeks the fate of G1-arrested human cells after treatment with nocodazole. We find that a small fraction of cells escapes from the arrest and resumes proliferation. These escaping cells experience reduced DNA damage and p21 activation. Cells surviving treatment are enriched for anti-apoptotic proteins, including Triap1. Increasing Triap1 levels allows cells to survive the first treatment with reduced DNA damage and lower levels of p21; accordingly, decreasing Triap1 re-sensitizes cells to nocodazole. We show that Triap1 upregulation leads to the retention of cytochrome c in the mitochondria, opposing the partial activation of caspases caused by nocodazole. In summary, our results point to a potential role of Triap1 upregulation in the emergence of resistance to drugs that induce prolonged mitotic arrest.

Keywords:  CP: Cell biology; CP: Molecular biology; cell cycle; microtubule targeting drugs; mitosis; sublethal caspase activation

DOI:  https://doi.org/10.1016/j.celrep.2023.112215
bioRxiv. 2023 Mar 02. pii: 2023.03.01.530611. [Epub ahead of print]

Actin-microtubule crosstalk imparts stiffness to the contractile ring in fission yeast.

Kimberly Bellingham-Johnstun, Zoe L Tyree, Jessica Martinez-Baird, Annelise Thorn, Caroline Laplante.

Actin-microtubule interactions are critical for cell division yet how these networks of polymers mutually influence their mechanical properties and functions in live cells remains unknown. In fission yeast, the post-anaphase array (PAA) of microtubules assembles in the plane of the contractile ring and its assembly relies on the Myp2p-dependent recruitment of Mto1p, a component of equatorial microtubule organizing centers (eMTOCs). The general organization of this array of microtubule and the impact on their physical attachment to the contractile ring remain unclear. We found that Myp2p facilitates the recruitment of Mto1p to the inner face of the contractile ring where the eMTOCs polymerize microtubules without their direct interaction. The PAA microtubules form a dynamic polygon of Ase1p crosslinked microtubules inside the contractile ring. The specific loss of PAA microtubules affects the mechanical properties of the contractile ring of actin by lowering its stiffness. This change in the mechanical properties of the ring has no measurable impact on cytokinesis or on the anchoring of the ring. Our work proposes that the PAA microtubules exploit the contractile ring for their assembly and function during cell division while the contractile ring may receive no benefit from these interactions.

DOI: https://doi.org/10.1101/2023.03.01.530611
ACS Pharmacol Transl Sci. 2023 Mar 10. 6(3): 422-446

Structural Optimization and Anticancer Activity of Polo-like Kinase 1 (Plk1) Polo-Box Domain (PBD) Inhibitors and Their Prodrugs.

Jung-Eun Park, Hobin Lee, Paola Oliva, Klara Kirsch, Bora Kim, Jong Il Ahn, Celeste N Alverez, Snehal Gaikwad, Kristopher W Krausz, Robert O'Connor, Ganesha Rai, Anton Simeonov, Beverly A Mock, Frank J Gonzalez, Kyung S Lee, Kenneth A Jacobson.

Polo-like kinase 1 (Plk1), a mitotic kinase whose activity is widely upregulated in various human cancers, is considered an attractive target for anticancer drug discovery. Aside from the kinase domain, the C-terminal noncatalytic polo-box domain (PBD), which mediates the interaction with the enzyme's binding targets or substrates, has emerged as an alternative target for developing a new class of inhibitors. Various reported small molecule PBD inhibitors exhibit poor cellular efficacy and/or selectivity. Here, we report structure-activity relationship (SAR) studies on triazoloquinazolinone-derived inhibitors, such as 43 (a 1-thioxo-2,4-dihydrothieno[2,3-e][1,2,4]triazolo[4,3-a]pyrimidin-5(1H)-one) that effectively block Plk1, but not Plk2 and Plk3 PBDs, with improved affinity and drug-like properties. The range of prodrug moieties needed for thiol group masking of the active drugs has been expanded to increase cell permeability and mechanism-based cancer cell (L363 and HeLa) death. For example, a 5-thio-1-methyl-4-nitroimidazolyl prodrug 80, derived from 43, showed an improved cellular potency (GI50 4.1 μM). As expected, 80 effectively blocked Plk1 from localizing to centrosomes and kinetochores and consequently induced potent mitotic block and apoptotic cell death. Another prodrug 78 containing 9-fluorophenyl in place of the thiophene-containing heterocycle in 80 also induced a comparable degree of anti-Plk1 PBD effect. However, orally administered 78 was rapidly converted in the bloodstream to parent drug 15, which was shown be relatively stable toward in vivo oxidation due to its 9-fluorophenyl group in comparison to unsubstituted phenyl. Further derivatization of these inhibitors, particularly to improve the systemic prodrug stability, could lead to a new class of therapeutics against Plk1-addicted cancers.

DOI: https://doi.org/10.1021/acsptsci.2c00250
Nat Commun. 2023 Mar 11. 14(1): 1353

Short-term molecular consequences of chromosome mis-segregation for genome stability.

Lorenza Garribba, Giuseppina De Feudis, Valentino Martis, Martina Galli, Marie Dumont, Yonatan Eliezer, René Wardenaar, Marica Rosaria Ippolito, Divya Ramalingam Iyer, Andréa E Tijhuis, Diana C J Spierings, Michael Schubert, Silvia Taglietti, Chiara Soriani, Simon Gemble, Renata Basto, Nick Rhind, Floris Foijer, Uri Ben-David, Daniele Fachinetti, Ylli Doksani, Stefano Santaguida.

Chromosome instability (CIN) is the most common form of genome instability and is a hallmark of cancer. CIN invariably leads to aneuploidy, a state of karyotype imbalance. Here, we show that aneuploidy can also trigger CIN. We found that aneuploid cells experience DNA replication stress in their first S-phase and precipitate in a state of continuous CIN. This generates a repertoire of genetically diverse cells with structural chromosomal abnormalities that can either continue proliferating or stop dividing. Cycling aneuploid cells display lower karyotype complexity compared to the arrested ones and increased expression of DNA repair signatures. Interestingly, the same signatures are upregulated in highly-proliferative cancer cells, which might enable them to proliferate despite the disadvantage conferred by aneuploidy-induced CIN. Altogether, our study reveals the short-term origins of CIN following aneuploidy and indicates the aneuploid state of cancer cells as a point mutation-independent source of genome instability, providing an explanation for aneuploidy occurrence in tumors.

DOI: https://doi.org/10.1038/s41467-023-37095-7
PLoS Pathog. 2023 Mar 16. 19(3): e1011255

The mitotic exit mediated by small GTPase Tem1 is essential for the pathogenicity of Fusarium graminearum.

Pengfei Miao, Xuzhao Mao, Shuang Chen, Yakubu Saddeeq Abubakar, Yulong Li, Wenhui Zheng, Jie Zhou, Zonghua Wang, Huawei Zheng.

The mitotic exit is a key step in cell cycle, but the mechanism of mitotic exit network in the wheat head blight fungus Fusarium graminearum remains unclear. F. graminearum infects wheat spikelets and colonizes the entire head by growing through the rachis node at the bottom of each spikelet. In this study, we found that a small GTPase FgTem1 plays an important role in F. graminearum pathogenicity and functions in regulating the formation of infection structures and invasive hyphal growth on wheat spikelets and wheat coleoptiles, but plays only little roles in vegetative growth and conidiation of the phytopathogen. FgTem1 localizes to both the inner nuclear periphery and the spindle pole bodies, and negatively regulates mitotic exit in F. graminearum. Furthermore, the regulatory mechanisms of FgTem1 have been further investigated by high-throughput co-immunoprecipitation and genetic strategies. The septins FgCdc10 and FgCdc11 were demonstrated to interact with the dominant negative form of FgTem1, and FgCdc11 was found to regulate the localization of FgTem1. The cell cycle arrest protein FgBub2-FgBfa1 complex was shown to act as the GTPase-activating protein (GAP) for FgTem1. We further demonstrated that a direct interaction exists between FgBub2 and FgBfa1 which crucially promotes conidiation, pathogenicity and DON production, and negatively regulates septum formation and nuclear division in F. graminearum. Deletions of FgBUB2 and FgBFA1 genes caused fewer perithecia and immature asci formations, and dramatically down-regulated trichothecene biosynthesis (TRI) gene expressions. Double deletion of FgBUB2/FgBFA1 genes showed that FgBUB2 and FgBFA1 have little functional redundancy in F. graminearum. In summary, we systemically demonstrated that FgTem1 and its GAP FgBub2-FgBfa1 complex are required for fungal development and pathogenicity in F. graminearum.

DOI: https://doi.org/10.1371/journal.ppat.1011255