Browse
Submit Data
Databases
API
Help

Dataset Information

26 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Dynamic organelle distribution initiates actin-based spindle migration in mouse oocytes.

ABSTRACT: Migration of meiosis-I (MI) spindle from the cell center to a sub-cortical location is a critical step for mouse oocytes to undergo asymmetric meiotic cell division. In this study, we investigate the mechanism by which formin-2 (FMN2) orchestrates the initial movement of MI spindle. By defining protein domains responsible for targeting FMN2, we show that spindle-periphery localized FMN2 is required for spindle migration. The spindle-peripheral FMN2 nucleates short actin bundles from vesicles derived likely from the endoplasmic reticulum (ER) and concentrated in a layer outside the spindle. This layer is in turn surrounded by mitochondria. A model based on polymerizing actin filaments pushing against mitochondria, thus generating a counter force on the spindle, demonstrated an inherent ability of this system to break symmetry and evolve directional spindle motion. The model is further supported through experiments involving spatially biasing actin nucleation via optogenetics and disruption of mitochondrial distribution and dynamics.

SUBMITTER: Duan X

PROVIDER: S-EPMC6959240 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

WHAMM is essential for spindle formation and spindle actin polymerization in maturing mouse oocytes.

Project description:WHAMM (WAS Protein Homolog Associated with Actin, Golgi Membranes, and Microtubules) is involved in Golgi membrane association, microtubule binding, and actin nucleation as a nucleation-promoting factor, which activates the actin-related protein 2/3 complex (the Arp2/3 complex). However, the role of WHAMM in mammalian oocyte maturation is poorly understood. The presence of WHAMM mRNA and protein during all stages of mouse oocyte maturation has been verified. It is mainly co-localized with the actin cage permeating the spindle during mouse oocyte maturation. Through the knockdown of WHAMM, we confirmed that it regulates spindle formation and affects the localization of the microtubule-organizing center (MTOC) during the early stages of spindle formation. Moreover, depletion of WHAMM impaired the formation of the spindle actin and chromosome alignment, which might be the cause of chromosomal aneuploidy and abnormal, asymmetric division. Treatment with brefeldin A (BFA), an inhibitor of vesicle transport from the endoplasmic reticulum (ER) to the Golgi apparatus, induced abnormal and dispersed localization of WHAMM. Taken together, these findings show that WHAMM is an essential component of the actin cytoskeleton machinery and plays a crucial role in oocyte maturation, presumably by controlling the formation of spindles with normal length by activating the formation of the spindle actin via the Arp2/3 complex.

| S-EPMC7889088 | biostudies-literature

An actin-dependent spindle position checkpoint ensures the asymmetric division in mouse oocytes.

Project description:Faithful chromosome segregation, during meiosis, is of critical importance to prevent aneuploidy in the resulting embryo. In mammalian oocytes, the segregation of homologous chromosomes takes place with the spindle located at the cell's periphery. The spindle is often assembled close to the centre of the cell, which necessitates the actin network for spindle transport to the cell cortex. In this study, we investigate how the segregation of chromosomes is coordinated with the positioning of the metaphase I spindle. We develop different assays to perturb the spindle's position and to delay its relocation to the cell periphery. We find that anaphase is delayed until the spindle is positioned in close proximity with the oocyte cortex. We further show that the metaphase arrest is dependent on a functional actin network, in addition to the spindle assembly checkpoint. Our work provides the first evidence for the existence of a functional spindle position checkpoint.

| S-EPMC4518315 | biostudies-literature

PLD2 regulates microtubule stability and spindle migration in mouse oocytes during meiotic division.

Project description:Phospholipase D2 (PLD2) is involved in cytoskeletal reorganization, cell migration, cell cycle progression, transcriptional control and vesicle trafficking. There is no evidence about PLD2 function in oocytes during meiosis. Herein, we analyzed PLD2 expression and its relationship with spindle formation and positioning in mouse oocyte meiosis. High protein level of PLD2 was revealed in oocytes by Western blot, which remained consistently stable from prophase I with intact germinal vesicle (GV) up to metaphase II (MII) stage. Immunofluorescence showed that PLD2 appeared and gathered around the condensed chromosomesafter germinal vesicle breakdown (GVBD), and co-localized with spindle from pro-metaphase I (pro-MI) to metaphase I (MI) and at MII stage. During anaphase I (Ana I) to telophase I (Tel I) transition, PLD2 was concentrated in the spindle polar area but absent from the midbody. In oocytes incubated with NFOT, an allosteric and catalytic inhibitor to PLD2, the spindle was enlarged and center-positioned, microtubules were resistant to cold-induced depolymerization and, additionally, the meiotic progression was arrested at MI stage. However, spindle migration could not be totally prevented by PLD2 catalytic specific inhibitors, FIPI and 1-butanol, implying at least partially, that PLD2 effect on spindle migration needs non-catalytic domain participation. NFOT-induced defects also resulted in actin-related molecules' distribution alteration, such as RhoA, phosphatidylinosital 4, 5- biphosphate (PIP2), phosphorylated Colifin and, consequently, unordered F-actin dynamics. Taken together, these data indicate PLD2 is required for the regulation of microtubule dynamics and spindle migration toward the cortex in mammalian oocytes during meiotic progression.

| S-EPMC5436581 | biostudies-literature

Dynamic Changes in pStat3 are Involved in Meiotic Spindle Assembly in Mouse Oocytes.

Project description:The signal transducer and activator of transcription 3 (Stat3) is activated upon phosphorylation at Y705 (pStat3) and serves the dual function of signal transduction and transcription activation. Our previous study suggested that pStat3 is functional during oocyte maturation when transcription is silenced. Therefore, we speculated that pStat3 serves other functions. Immunocytochemical analysis revealed that pStat3 emerges at microtubule asters and spindle and is subsequently localized at the spindle poles along with pericentrin during mouse oocyte maturation. Both Stat3 and pStat3 proteins were detected in conditionally knocked out Stat3-/- mouse oocytes. pStat3 localization was the same in Stat3+/+ and Stat3-/-oocytes, and oocyte maturation proceeded normally, suggesting that pStat3 was still functional. Furthermore, the treatment of oocytes with the Stat3-specific inhibitors stattic and BP-1-102 or anti-pStat3 antibody led to significantly abnormal spindle assembly and chromosome mislocation in a dose-dependent manner, and pStat3 was either absent or improperly localized in these oocytes. Moreover, the development of pre-implantation stage embryos derived from inhibitor-treated oocytes was significantly hampered following in vitro fertilization. These findings indicate a novel function of pStat3 in spindle assembly.

| S-EPMC7072877 | biostudies-literature

Actin-microtubule interplay coordinates spindle assembly in human oocytes.

Project description:Mammalian oocytes assemble a bipolar acentriolar microtubule spindle to segregate chromosomes during asymmetric division. There is increasing evidence that actin in the spindle interior not only participates in spindle migration and positioning but also protects oocytes from chromosome segregation errors leading to aneuploidy. Here we show that actin is an integral component of the meiotic machinery that closely interacts with microtubules during all major events of human oocyte maturation from the time point of spindle assembly till polar body extrusion and metaphase arrest. With the aid of drugs selectively affecting cytoskeleton dynamics and transiently disturbing the integrity of the two cytoskeleton systems, we identify interdependent structural rearrangements indicative of a close communication between actin and microtubules as fundamental feature of human oocytes. Our data support a model of actin-microtubule interplay that is essential for bipolar spindle assembly and correct partitioning of the nuclear genome in human oocyte meiosis.

| S-EPMC6789129 | biostudies-literature

Dynamic maintenance of asymmetric meiotic spindle position through Arp2/3-complex-driven cytoplasmic streaming in mouse oocytes.

Project description:Mature mammalian oocytes are poised for completing meiosis II (MII) on fertilization by positioning the spindle close to an actomyosin-rich cortical cap. Here, we show that the Arp2/3 complex localizes to the cortical cap in a Ran-GTPase-dependent manner and nucleates actin filaments in the cortical cap and a cytoplasmic actin network. Inhibition of Arp2/3 activity leads to rapid dissociation of the spindle from the cortex. Live-cell imaging and spatiotemporal image correlation spectroscopy analysis reveal that actin filaments flow continuously away from the Arp2/3-rich cortex, driving a cytoplasmic streaming expected to exert a net pushing force on the spindle towards the cortex. Arp2/3 inhibition not only diminishes this actin flow and cytoplasmic streaming but also enables a reverse streaming driven by myosin-II-based cortical contraction, moving the spindle away from the cortex. Thus, the asymmetric MII spindle position is dynamically maintained as a result of balanced forces governed by the Arp2/3 complex.

| S-EPMC3523671 | biostudies-literature

Microtubule organizing centers regulate spindle positioning in mouse oocytes.

Project description:During female meiosis I (MI), spindle positioning must be tightly regulated to ensure the fidelity of the first asymmetric division and faithful chromosome segregation. Although the role of F-actin in regulating these critical processes has been studied extensively, little is known about whether microtubules (MTs) participate in regulating these processes. Using mouse oocytes as a model system, we characterize a subset of MT organizing centers that do not contribute directly to spindle assembly, termed mcMTOCs. Using laser ablation, STED super-resolution microscopy, and chemical manipulation, we show that mcMTOCs are required to regulate spindle positioning and faithful chromosome segregation during MI. We discuss how forces exerted by F-actin on the spindle are balanced by mcMTOC-nucleated MTs to anchor the spindle centrally and to regulate its timely migration. Our findings provide a model for asymmetric cell division, complementing the current F-actin-based models, and implicate mcMTOCs as a major player in regulating spindle positioning.

| S-EPMC8792338 | biostudies-literature

Axin-1 Regulates Meiotic Spindle Organization in Mouse Oocytes.

Project description:Axin-1, a negative regulator of Wnt signaling, is a versatile scaffold protein involved in centrosome separation and spindle assembly in mitosis, but its function in mammalian oogenesis remains unknown. Here we examined the localization and function of Axin-1 during meiotic maturation in mouse oocytes. Immunofluorescence analysis showed that Axin-1 was localized around the spindle. Knockdown of the Axin1 gene by microinjection of specific short interfering (si)RNA into the oocyte cytoplasm resulted in severely defective spindles, misaligned chromosomes, failure of first polar body (PB1) extrusion, and impaired pronuclear formation. However, supplementing the culture medium with the Wnt pathway activator LiCl improved spindle morphology and pronuclear formation. Downregulation of Axin1 gene expression also impaired the spindle pole localization of γ-tubulin/Nek9 and resulted in retention of the spindle assembly checkpoint protein BubR1 at kinetochores after 8.5 h of culture. Our results suggest that Axin-1 is critical for spindle organization and cell cycle progression during meiotic maturation in mouse oocytes.

| S-EPMC4902301 | biostudies-literature

Cdk1 inactivation induces post-anaphase-onset spindle migration and membrane protrusion required for extreme asymmetry in mouse oocytes.

Project description:Female meiotic divisions are extremely asymmetric, producing large oocytes and small polar bodies (PBs). In mouse oocytes, the spindle relocates to the cortex before anaphase of meiosis I (MI). It is presumed that by displacing the future midzone, pre-anaphase spindle repositioning alone ensures asymmetry. But how subsequent anaphase events might contribute to asymmetric PB extrusion (PBE) is unknown. Here, we find that inactivation of cyclin-dependent kinase 1 (Cdk1) induces anaphase and simultaneously triggers cytoplasmic formin-mediated F-actin polymerisation that propels the spindle into the cortex causing it to protrude while anaphase progresses. Significantly, if post-anaphase-onset spindle migration fails, protrusion and asymmetry are severely threatened even with intact pre-anaphase migration. Conversely, post-anaphase migration can completely compensate for failed pre-anaphase migration. These data identify a cell-cycle-triggered phase of spindle displacement occurring after anaphase-onset, which, by inducing protrusion, is necessary for extreme asymmetry in mouse oocytes and uncover a pathway for maximising unequal division.

| S-EPMC6168559 | biostudies-literature

Mouse oocytes differentiate through organelle enrichment from sister cyst germ cells.

Project description:Oocytes differentiate in diverse species by receiving organelles and cytoplasm from sister germ cells while joined in germline cysts or syncytia. Mouse primordial germ cells form germline cysts, but the role of cysts in oogenesis is unknown. We find that mouse germ cells receive organelles from neighboring cyst cells and build a Balbiani body to become oocytes, whereas nurselike germ cells die. Organelle movement, Balbiani body formation, and oocyte fate determination are selectively blocked by low levels of microtubule-dependent transport inhibitors. Membrane breakdown within the cyst and an apoptosis-like process are associated with organelle transfer into the oocyte, events reminiscent of nurse cell dumping in Drosophila We propose that cytoplasmic and organelle transport plays an evolutionarily conserved and functionally important role in mammalian oocyte differentiation.

| S-EPMC6910648 | 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