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Kimura K, Motegi F. Fluid flow dynamics in cellular patterning. Semin Cell Dev Biol 2021; 120:3-9. [PMID: 34274213 DOI: 10.1016/j.semcdb.2021.07.004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2021] [Revised: 06/24/2021] [Accepted: 07/01/2021] [Indexed: 10/20/2022]
Abstract
The development of complex forms of multicellular organisms depends on the spatial arrangement of cellular architecture and functions. The interior design of the cell is patterned by spatially biased distributions of molecules and biochemical reactions in the cytoplasm and/or on the plasma membrane. In recent years, a dynamic change in the cytoplasmic fluid flow has emerged as a key physical process of driving long-range transport of molecules to particular destinations within the cell. Here, recent experimental advances in the understanding of the generation of the various types of cytoplasmic flows and contributions to intracellular patterning are reviewed with a particular focus on feedback mechanisms between the mechanical properties of fluid flow and biochemical signaling during animal cell polarization.
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Affiliation(s)
- Kenji Kimura
- School of Science and Technology, Kwansei Gakuin University, Japan.
| | - Fumio Motegi
- Instiute for Genetic Medicine, Hokkaido University, Japan; Temasek Lifesciences Laboratory, Singapore; Mechanobiology Institute, National University of Singapore, Singapore; Department of Biological Sciences, National University of Singapore, Singapore.
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Qi R, Xu N, Wang G, Ren H, Li S, Lei J, Lin Q, Wang L, Gu X, Zhang H, Jiang Q, Zhang C. The lamin-A/C-LAP2α-BAF1 protein complex regulates mitotic spindle assembly and positioning. J Cell Sci 2015; 128:2830-41. [PMID: 26092935 DOI: 10.1242/jcs.164566] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Accepted: 06/15/2015] [Indexed: 01/31/2023] Open
Abstract
Some nuclear proteins that are crucial in interphase relocate during the G2/M-phase transition in order to perform their mitotic functions. However, how they perform these functions and the underlying mechanisms remain largely unknown. Here, we report that a fraction of the nuclear periphery proteins lamin-A/C, LAP2α and BAF1 (also known as BANF1) relocate to the spindle and the cell cortex in mitosis. Knockdown of these proteins by using RNA interference (RNAi) induces short and fluffy spindle formation, and disconnection of the spindle from the cell cortex. Disrupting the microtubule assembly leads to accumulation of these proteins in the cell cortex, whereas depolymerizing the actin microfilaments results in the formation of short spindles. We further demonstrate that these proteins are part of a stable complex that links the mitotic spindle to the cell cortex and the spindle matrix by binding to spindle-associated dynein, the actin filaments in the cell cortex and the spindle matrix. Taken together, our findings unveil a unique mechanism where the nuclear periphery proteins lamin-A/C, LAP2α and BAF1 are assembled into a protein complex during mitosis in order to regulate assembly and positioning of the mitotic spindle.
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Affiliation(s)
- Ran Qi
- The Ministry of Education Key Laboratory of Cell Proliferation and Differentiation and the State Key Laboratory of Membrane Biology, College of Life Sciences, Beijing 100871, China
| | - Nan Xu
- The Ministry of Education Key Laboratory of Cell Proliferation and Differentiation and the State Key Laboratory of Membrane Biology, College of Life Sciences, Beijing 100871, China
| | - Gang Wang
- The Ministry of Education Key Laboratory of Cell Proliferation and Differentiation and the State Key Laboratory of Membrane Biology, College of Life Sciences, Beijing 100871, China
| | - He Ren
- The Ministry of Education Key Laboratory of Cell Proliferation and Differentiation and the State Key Laboratory of Membrane Biology, College of Life Sciences, Beijing 100871, China
| | - Si Li
- The Ministry of Education Key Laboratory of Cell Proliferation and Differentiation and the State Key Laboratory of Membrane Biology, College of Life Sciences, Beijing 100871, China
| | - Jun Lei
- The Ministry of Education Key Laboratory of Cell Proliferation and Differentiation and the State Key Laboratory of Membrane Biology, College of Life Sciences, Beijing 100871, China
| | - Qiaoyu Lin
- The Ministry of Education Key Laboratory of Cell Proliferation and Differentiation and the State Key Laboratory of Membrane Biology, College of Life Sciences, Beijing 100871, China
| | - Lihao Wang
- The Ministry of Education Key Laboratory of Cell Proliferation and Differentiation and the State Key Laboratory of Membrane Biology, College of Life Sciences, Beijing 100871, China
| | - Xin Gu
- The Ministry of Education Key Laboratory of Cell Proliferation and Differentiation and the State Key Laboratory of Membrane Biology, College of Life Sciences, Beijing 100871, China
| | - Hongyin Zhang
- Cancer Research Center, Peking University Hospital, Peking University, Beijing 100871, China
| | - Qing Jiang
- The Ministry of Education Key Laboratory of Cell Proliferation and Differentiation and the State Key Laboratory of Membrane Biology, College of Life Sciences, Beijing 100871, China
| | - Chuanmao Zhang
- The Ministry of Education Key Laboratory of Cell Proliferation and Differentiation and the State Key Laboratory of Membrane Biology, College of Life Sciences, Beijing 100871, China
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Parte S, Bhartiya D, Patel H, Daithankar V, Chauhan A, Zaveri K, Hinduja I. Dynamics associated with spontaneous differentiation of ovarian stem cells in vitro. J Ovarian Res 2014; 7:25. [PMID: 24568237 PMCID: PMC4234975 DOI: 10.1186/1757-2215-7-25] [Citation(s) in RCA: 53] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 02/17/2014] [Indexed: 01/26/2023] Open
Abstract
BACKGROUND Recent studies suggest that ovarian germ line stem cells replenish oocyte-pool in adult stage, and challenge the central doctrine of 'fixed germ cell pool' in mammalian reproductive biology. Two distinct populations of spherical stem cells with high nucleo-cytoplasmic ratio have been recently identified in the adult mammalian ovary surface epithelium (OSE) including nuclear OCT-4A positive very small embryonic-like (VSELs) and cytoplasmic OCT-4 expressing ovarian germ stem cells (OGSCs). Three weeks culture of scraped OSE cells results in spontaneous differentiation of the stem cells into oocyte-like, parthenote-like, embryoid body-like structures and also embryonic stem cell-like colonies whereas epithelial cells attach and transform into a bed of mesenchymal cells. Present study was undertaken, to further characterize ovarian stem cells and to comprehend better the process of spontaneous differentiation of ovarian stem cells into oocyte-like structures in vitro. METHODS Ovarian stem cells were enriched by immunomagnetic sorting using SSEA-4 as a cell surface marker and were further characterized. Stem cells and clusters of OGSCs (reminiscent of germ cell nests in fetal ovaries), were characterized by immuno-localization for stem and germ cell specific markers and spontaneous differentiation in OSE cultures was studied by live cell imaging. RESULTS Differential expression of markers specific for pluripotent VSELs (nuclear OCT-4A, SSEA-4, CD133), OGSCs (cytoplasmic OCT-4) primordial germ cells (FRAGILIS, STELLA, VASA) and germ cells (DAZL, GDF-9, SCP-3) were studied. Within one week of culture, stem cells became bigger in size, developed abundant cytoplasm, differentiated into germ cells, revealed presence of Balbiani body-like structure (mitochondrial cloud) and exhibited characteristic cytoplasmic streaming. CONCLUSIONS Presence of germ cell nests, Balbiani body-like structures and cytoplasmic streaming extensively described during fetal ovary development, are indeed well recapitulated during in vitro oogenesis in adult OSE cultures along with characteristic expression of stem/germ cell/oocyte markers. Further studies are required to assess the genetic integrity of in vitro derived oocytes before harnessing their clinical potential. Advance in our knowledge about germ cell differentiation from stem cells will enable researchers to design better in vitro strategies which in turn may have relevance to reproductive biology and regenerative medicine.
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Behaviour of cytoplasmic organelles and cytoskeleton during oocyte maturation. Reprod Biomed Online 2013; 28:284-99. [PMID: 24444815 DOI: 10.1016/j.rbmo.2013.10.016] [Citation(s) in RCA: 97] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/18/2013] [Revised: 10/16/2013] [Accepted: 10/17/2013] [Indexed: 11/21/2022]
Abstract
Assisted reproduction technology (ART) has become an attractive option for infertility treatment and holds tremendous promise. However, at present, there is still room for improvement in its success rates. Oocyte maturation is a process by which the oocyte becomes competent for fertilization and subsequent embryo development. To better understand the mechanism underlying oocyte maturation and for the future improvement of assisted reproduction technology, this review focuses on the complex processes of cytoplasmic organelles and the dynamic alterations of the cytoskeleton that occur during oocyte maturation. Ovarian stimulation and in-vitro maturation are the major techniques used in assisted reproduction technology and their influence on the organelles of oocytes is also discussed. Since the first birth by assisted reproduction treatment was achieved in 1978, numerous techniques involved in assisted reproduction have been developed and have become attractive options for infertility treatment. However, the unsatisfactory success rate remains as a main challenge. Oocyte maturation is a process by which the oocyte becomes competent for fertilization and subsequent embryo development. Oocyte maturation includes both nuclear and cytoplasmic maturation. Nuclear maturation primarily involves chromosomal segregation, which has been well studied, whereas cytoplasmic maturation involves a series of complicated processes, and there are still many parts of this process that remain controversial. Ovarian stimulation and in-vitro maturation (IVM) are the major techniques of assisted reproduction. The effect of ovarian stimulation or IVM on the behaviour of cell organelles of the oocyte has been postulated as the reason for the reduced developmental potential of in-vitro-produced embryos. To further understanding of the mechanism of oocyte maturation and future improvement of assisted reproduction treatment, the complex events of cytoplasmic organelles and the cytoskeleton that occur during oocyte maturation and the influence of ovarian stimulation and IVM on these organelles are described in this review.
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Iwase S, Sato R, De Bock PJ, Gevaert K, Fujiki S, Tawada T, Kuchitsu M, Yamagishi Y, Ono S, Abe H. Activation of ADF/cofilin by phosphorylation-regulated Slingshot phosphatase is required for the meiotic spindle assembly in Xenopus laevis oocytes. Mol Biol Cell 2013; 24:1933-46. [PMID: 23615437 PMCID: PMC3681698 DOI: 10.1091/mbc.e12-12-0851] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
We identify Xenopus ADF/cofilin (XAC) and its activator, Slingshot phosphatase (XSSH), as key regulators of actin dynamics essential for spindle microtubule assembly during Xenopus oocyte maturation. Phosphorylation of XSSH at multiple sites within the tail domain occurs just after germinal vesicle breakdown (GVBD) and is accompanied by dephosphorylation of XAC, which was mostly phosphorylated in immature oocytes. This XAC dephosphorylation after GVBD is completely suppressed by latrunculin B, an actin monomer-sequestering drug. On the other hand, jasplakinolide, an F-actin-stabilizing drug, induces dephosphorylation of XAC. Effects of latrunculin B and jasplakinolide are reconstituted in cytostatic factor-arrested extracts (CSF extracts), and XAC dephosphorylation is abolished by depletion of XSSH from CSF extracts, suggesting that XSSH functions as an actin filament sensor to facilitate actin filament dynamics via XAC activation. Injection of anti-XSSH antibody, which blocks full phosphorylation of XSSH after GVBD, inhibits both meiotic spindle formation and XAC dephosphorylation. Coinjection of constitutively active XAC with the antibody suppresses this phenotype. Treatment of oocytes with jasplakinolide also impairs spindle formation. These results strongly suggest that elevation of actin dynamics by XAC activation through XSSH phosphorylation is required for meiotic spindle assembly in Xenopus laevis.
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Affiliation(s)
- Shohei Iwase
- Department of Nanobiology, Graduate School of Advanced Integration Science, Chiba University, Chiba 263-8522, Japan
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Dehapiot B, Carrière V, Carroll J, Halet G. Polarized Cdc42 activation promotes polar body protrusion and asymmetric division in mouse oocytes. Dev Biol 2013; 377:202-12. [PMID: 23384564 PMCID: PMC3690527 DOI: 10.1016/j.ydbio.2013.01.029] [Citation(s) in RCA: 79] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/30/2012] [Revised: 12/22/2012] [Accepted: 01/25/2013] [Indexed: 11/28/2022]
Abstract
Asymmetric meiotic divisions in mammalian oocytes rely on the eccentric positioning of the spindle and the remodeling of the overlying cortex, resulting in the formation of small polar bodies. The mechanism of this cortical polarization, exemplified by the formation of a thick F-actin cap, is poorly understood. Cdc42 is a major player in cell polarization in many systems; however, the spatio-temporal dynamics of Cdc42 activation during oocyte meiosis, and its contribution to mammalian oocyte polarization, have remained elusive. In this study, we investigated Cdc42 activation (Cdc42–GTP), dynamics and role during mouse oocyte meiotic divisions. We show that Cdc42–GTP accumulates in restricted cortical regions overlying meiotic chromosomes or chromatids, in a Ran–GTP-dependent manner. This polarized activation of Cdc42 is required for the recruitment of N-WASP and the formation of F-actin-rich protrusions during polar body formation. Cdc42 inhibition in MII oocytes resulted in the release of N-WASP into the cytosol, a loss of the polarized F-actin cap, and a failure to protrude the second polar body. Cdc42 inhibition also resulted in central spindle defects in activated MII oocytes. In contrast, emission of the first polar body during oocyte maturation could occur in the absence of a functional Cdc42/N-WASP pathway. Therefore, Cdc42 is a new protagonist in chromatin-induced cortical polarization in mammalian oocytes, with an essential role in meiosis II completion, through the recruitment and activation of N-WASP, downstream of the chromatin-centered Ran–GTP gradient.
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Affiliation(s)
- Benoit Dehapiot
- CNRS, UMR 6290, Institut de Génétique et Développement de Rennes, F-35043 Rennes, France
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Maddox AS, Azoury J, Dumont J. Polar body cytokinesis. Cytoskeleton (Hoboken) 2012; 69:855-68. [PMID: 22927361 DOI: 10.1002/cm.21064] [Citation(s) in RCA: 41] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2012] [Accepted: 08/20/2012] [Indexed: 02/04/2023]
Abstract
Polar body cytokinesis is the physical separation of a small polar body from a larger oocyte or ovum. This maternal meiotic division shares many similarities with mitotic and spermatogenic cytokinesis, but there are several distinctions, which will be discussed in this review. We synthesize results from many different model species, including those popular for their genetics and several that are more obscure in modern cell biology. The site of polar body division is determined before anaphase, by the eccentric, cortically associated meiotic spindle. Depending on the species, either the actin or microtubule cytoskeleton is required for spindle anchoring. Chromatin is necessary and sufficient to elicit differentiation of the associated cortex, via Ran-based signaling. The midzone of the anaphase spindle serves as a hub for regulatory complexes that elicit Rho activation, and ultimately actomyosin contractile ring assembly and contraction. Polar body cytokinesis uniquely requires another Rho family GTPase, Cdc42, for dynamic reorganization of the polar cortex. This is perhaps due to the considerable asymmetry of this division, wherein the polar body and the oocyte/ovum have distinct fates and very different sizes. Thus, maternal meiotic cytokinesis appears to occur via simultaneous polar relaxation and equatorial contraction, since the polar body is extruded from the spherical oocyte through the nascent contractile ring. As such, polar body cytokinesis is an interesting and important variation on the theme of cell division.
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Affiliation(s)
- Amy Shaub Maddox
- Institut de recherche en immunology et en cancerologie (IRIC), Université de Montréal, Montréal, Quebec, Canada.
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Spindle positioning in mammalian oocytes. Exp Cell Res 2012; 318:1442-7. [PMID: 22406266 DOI: 10.1016/j.yexcr.2012.02.019] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/21/2011] [Revised: 02/21/2012] [Accepted: 02/22/2012] [Indexed: 11/22/2022]
Abstract
To preserve the maternal stores accumulated during oogenesis for further embryo development, oocytes divide asymmetrically which minimizes the volume of cytoplasm lost with each set of haploid genome. To ensure asymmetric division to occur, oocytes have to position their division spindle asymmetrically as well as tailor the size of daughter cells to the chromatin mass. In this review, we will discuss the recent advances in the field, with emphasis on the control mechanisms involved in meiotic spindle positioning in mammalian oocytes.
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