Browse
Submit Data
Databases
API
Help

Dataset Information

24 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Mdm2-Mediated Downmodulation of GRK2 Restricts Centrosome Separation for Proper Chromosome Congression.

ABSTRACT: The timing of centrosome separation and the distance moved apart influence the formation of the bipolar spindle, affecting chromosome stability. Epidermal growth factor receptor (EGFR) signaling induces early centrosome separation through downstream G protein-coupled receptor kinase GRK2, which phosphorylates the Hippo pathway component MST2 (Mammalian STE20-like protein kinase 2), in turn allowing NIMA kinase Nek2A activation for centrosomal linker disassembly. However, the mechanisms that counterbalance centrosome disjunction and separation remain poorly understood. We unveil that timely degradation of GRK2 by the E3 ligase Mdm2 limits centrosome separation in the G2. Both knockout expression and catalytic inhibition of Mdm2 result in GRK2 accumulation and enhanced centrosome separation before mitosis onset. Phosphorylation of GRK2 on residue S670 enables a complex pattern of non-K48-linked polyubiquitin chains assembled by Mdm2, which correlate with kinase protein degradation. Remarkably, GRK2-S670A protein fails to phosphorylate MST2 despite overcoming Mdm2-dependent degradation, which results in defective centrosome separation, shorter spindles, and abnormal chromosome congression. Conversely, extra levels of wild-type kinase in the G2 cause increased inter-centrosome distances with longer spindles, also converging in congression issues. Our findings show that the signals enabling activity of the GRK2/MST2/Nek2A axis for separation also switches on Mdm2 degradation of GRK2 to ensure accurate centrosome dynamics and proper mitotic spindle functionality.

SUBMITTER: Reglero C

PROVIDER: S-EPMC8064503 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

MKLP2 functions in early mitosis to ensure proper chromosome congression.

Project description:Mitotic kinesin-like protein 2 (MKLP2; also known as KIF20A) is a motor protein with a well-established function in promoting cytokinesis. However, our results with siRNAs targeting MKLP2 and small-molecule inhibitors of MKLP2 (MKLP2i) suggest that it also has a function earlier in mitosis, prior to anaphase. In this study, we provide direct evidence that MKLP2 facilitates chromosome congression in prometaphase. We employed live imaging to observe HeLa cells with fluorescently tagged histones treated with MKLP2i and discovered a pronounced chromosome congression defect. We show that MKLP2 facilitates error correction, as inhibited cells have a significant increase in unstable, syntelic kinetochore-microtubule attachments. We find that the aberrant attachments are accompanied by elevated Aurora kinase (A and B) activity and phosphorylation of the downstream target HEC1 (also known as NDC80) at Ser55. Finally, we show that MKLP2 inhibition results in aneuploidy, confirming that MKLP2 safeguards cells against chromosomal instability. This article has an associated First Person interview with the first author of the paper.

| S-EPMC9270953 | biostudies-literature

Beclin-1 is required for chromosome congression and proper outer kinetochore assembly.

Project description:The functions of Beclin-1 in macroautophagy, tumorigenesis and cytokinesis are thought to be mediated by its association with the PI3K-III complex. Here, we describe a new role for Beclin-1 in mitotic chromosome congression that is independent of the PI3K-III complex and its role in autophagy. Beclin-1 depletion in HeLa cells leads to a significant reduction of the outer kinetochore proteins CENP-E, CENP-F and ZW10, and, consequently, the cells present severe problems in chromosome congression. Beclin-1 associates with kinetochore microtubules and forms discrete foci near the kinetochores of attached chromosomes. We show that Beclin-1 interacts directly with Zwint-1-a component of the KMN (KNL-1/Mis12/Ndc80) complex-which is essential for kinetochore-microtubule interactions. This suggests that Beclin-1 acts downstream of the KMN complex to influence the recruitment of outer kinetochore proteins and promotes accurate kinetochore anchoring to the spindle during mitosis.

| S-EPMC3615652 | biostudies-literature

Cyclin B2 and p53 control proper timing of centrosome separation.

Project description:Cyclins B1 and B2 are frequently elevated in human cancers and are associated with tumour aggressiveness and poor clinical outcome; however, whether and how B-type cyclins drive tumorigenesis is unknown. Here we show that cyclin B1 and B2 transgenic mice are highly prone to tumours, including tumour types where B-type cyclins serve as prognosticators. Cyclins B1 and B2 both induce aneuploidy when overexpressed but through distinct mechanisms, with cyclin B1 inhibiting separase activation, leading to anaphase bridges, and cyclin B2 triggering aurora-A-mediated Plk1 hyperactivation, resulting in accelerated centrosome separation and lagging chromosomes. Complementary experiments revealed that cyclin B2 and p53 act antagonistically to control aurora-A-mediated centrosome splitting and accurate chromosome segregation in normal cells. These data demonstrate a causative link between B-type cyclin overexpression and tumour pathophysiology, and uncover previously unknown functions of cyclin B2 and p53 in centrosome separation that may be perturbed in many human cancers.

| S-EPMC4379487 | biostudies-literature

Centrosomal Actin Assembly Is Required for Proper Mitotic Spindle Formation and Chromosome Congression.

Project description:Cytoskeletal cross talk between actin filaments and microtubules is a common mechanism governing the assembly of cellular structures, i.e., during filopodia formation or cilia organization. However, potential actin-microtubule interactions during mammalian cell divisions are less well understood. At mitotic entry, centrosomes propagate the formation of the mitotic spindle, thereby aligning individual chromosomes to the metaphase plate, a process coined chromosome congression. Here, we identify actin filament assembly spatially defined at centrosomes contemporaneously with spindle microtubules forming during prometaphase. We show that pharmacological Arp2/3 complex inhibition as well as overexpression of the Arp2/3 complex inhibitory protein Arpin decreased spindle actin. As a consequence, mitotic spindle formation is impaired, which resulted in disorganized chromosome congression and ultimately mitotic defects in non-transformed cells. Thus centrosomal Arp2/3 complex activity plays a role in the maintenance of genomic integrity during mitosis.

| S-EPMC6520610 | biostudies-literature

Kinesin-5 mediated chromosome congression in insect spindles.

Project description:IntroductionThe microtubule motor protein kinesin-5 is well known to establish the bipolar spindle by outward sliding of antiparallel interpolar microtubules. In yeast, kinesin-5 also facilitates chromosome alignment "congression" at the spindle equator by preferentially depolymerizing long kinetochore microtubules (kMTs). The motor protein kinesin-8 has also been linked to chromosome congression. Therefore, we sought to determine whether kinesin-5 or kinesin-8 facilitates chromosome congression in insect spindles.MethodsRNAi of the kinesin-5 Klp61F and kinesin-8 Klp67A were performed separately in Drosophila melanogaster S2 cells to test for inhibited chromosome congression. Klp61F RNAi, Klp67A RNAi, and control metaphase mitotic spindles expressing fluorescent tubulin and fluorescent Cid were imaged, and their fluorescence distributions were compared.ResultsRNAi of Klp61F with a weak Klp61F knockdown resulted in longer kMTs and less congressed kinetochores compared to control over a range of conditions, consistent with kinesin-5 length-dependent depolymerase activity. RNAi of the kinesin-8 Klp67A revealed that kMTs relative to the spindle lengths were not longer compared to control, but rather that the spindles were longer, indicating that Klp67A acts preferentially as a length-dependent depolymerase on interpolar microtubules without significantly affecting kMT length and chromosome congression.ConclusionsThis study demonstrates that in addition to establishing the bipolar spindle, kinesin-5 regulates kMT length to facilitate chromosome congression in insect spindles. It expands on previous yeast studies, and it expands the role of kinesin-5 to include kMT assembly regulation in eukaryotic mitosis.

| S-EPMC5849273 | biostudies-literature

Beclin-1 is dispensable for chromosome congression and proper outer kinetochore assembly

Project description:Chromosomal instability (CIN) is defined by the propensity to acquire structural and/or numerical aberration in the normal cellular karyotype and is often associated with cancer. Autophagy is a catabolic process that leads to the recycling of cellular components that may positively or negatively impact on cancer development and progression, depending on the context. Recent work postulated that the depletion of the pro-autophagic and tumor suppressive protein Beclin 1 triggers CIN by interfering with mitotic chromosome segregation, providing a possible mechanism for how Beclin 1 can act as a tumor suppressor (Fremont et al., PMID: 23478334). Here, we present data supporting the notion that the phenotypes described in Fremont et al., depend on a siRNA off-target effect. The transcriptomic analysis shown here was designed to identify the factor(s) that are responsible for such phenotype. HeLa cells synchronized in mitosis have been transfected in 3 independent experiments with either Beclin 1-ER or Beclin 1-II siRNA. RNA was extracted and subjected to gene expression profiling. Differentially expressed probe sets/genes have been identified between the ER and II siRNA using the moderated t-test from Bioconductor's limma package with the resulting p-values being adjusted for multiple hypothesis testing using the method from Benjamini and Hochberg.

2015-09-02 | E-GEOD-69052 | biostudies-arrayexpress

Beclin-1 is dispensable for chromosome congression and proper outer kinetochore assembly

2015-09-02 | GSE69052 | GEO

Timing of centrosome separation is important for accurate chromosome segregation.

Project description:Spindle assembly, establishment of kinetochore attachment, and sister chromatid separation must occur during mitosis in a highly coordinated fashion to ensure accurate chromosome segregation. In most vertebrate cells, the nuclear envelope must break down to allow interaction between microtubules of the mitotic spindle and the kinetochores. It was previously shown that nuclear envelope breakdown (NEB) is not coordinated with centrosome separation and that centrosome separation can be either complete at the time of NEB or can be completed after NEB. In this study, we investigated whether the timing of centrosome separation affects subsequent mitotic events such as establishment of kinetochore attachment or chromosome segregation. We used a combination of experimental and computational approaches to investigate kinetochore attachment and chromosome segregation in cells with complete versus incomplete spindle pole separation at NEB. We found that cells with incomplete spindle pole separation exhibit higher rates of kinetochore misattachments and chromosome missegregation than cells that complete centrosome separation before NEB. Moreover, our mathematical model showed that two spindle poles in close proximity do not "search" the entire cellular space, leading to formation of large numbers of syntelic attachments, which can be an intermediate stage in the formation of merotelic kinetochores.

| S-EPMC3268720 | biostudies-literature

The tetrameric kinesin Kif25 suppresses pre-mitotic centrosome separation to establish proper spindle orientation.

Project description:Microtubules tether centrosomes together during interphase. How this is accomplished and what benefit it provides to the cell is not known. We have identified a bipolar, minus-end-directed kinesin, Kif25, that suppresses centrosome separation. Kif25 is required to prevent premature centrosome separation during interphase. We show that premature centrosome separation leads to microtubule-dependent nuclear translocation, culminating in eccentric nuclear positioning that disrupts the cortical spindle positioning machinery. The activity of Kif25 during interphase is required to maintain a centred nucleus to ensure the spindle is stably oriented at the onset of mitosis.

| S-EPMC5376238 | biostudies-literature

Integrin-Mediated Adhesion Promotes Centrosome Separation in Early Mitosis.

Project description:Integrin-mediated adhesion to the extracellular matrix is a key regulator of the cell cycle, as demonstrated for the passage of the G1/S checkpoint and the completion of cytokinetic abscission. Here, integrin-dependent regulation of the cell cycle in G2 and early M phases was investigated. The progression through the G2 and M phases was monitored by live-cell imaging and immunofluorescence staining in adherent and non-adherent fibroblast cells. Non-adherent cells, as well as adherent cells lacking FAK activity due to suppressed expression or pharmacological inhibition, exhibited a prolonged G2 phase and severely defect centrosome separation, resulting in delayed progress through the early mitotic stages. The activation of the critical mitotic regulator PLK1 and its indirect target Eg5, a kinesin-family motor protein driving the centrosome separation, were reduced in the cells lacking FAK activity. Furthermore, the absence of integrin adhesion or FAK activity destabilized the structural integrity of centrosomes and often caused detachment of pericentriolar material from the centrioles. These data identify a novel adhesion-dependent mechanism by which integrins via FAK and PLK1 contribute to the regulation of the cell cycle in the G2 and early M phases, and to the maintenance of genome integrity.

| S-EPMC9030014 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data