BubR1 phosphorylates CENP-E as a switch enabling the transition from lateral association to end-on capture of spindle microtubules

Abstract Microtubule-severing protein (MTSP) is critical for the survival of both mitotic and postmitotic cells. However, the study of MTSP during meiosis of mammalian oocytes has not been reported. We found that spastin, a member of the MTSP family, was highly expressed in oocytes and aggregated in spindle microtubules. After knocking down spastin by specific siRNA, the spindle microtubule density of meiotic oocytes decreased significantly. When the oocytes were cultured in vitro, the oocytes lacking spastin showed an obvious maturation disorder. Considering the microtubule-severing activity of spastin, we speculate that spastin on spindles may increase the number of microtubule broken ends by severing the microtubules, therefore playing a nucleating role, promoting spindle assembly and ensuring normal meiosis. In addition, we found the colocalization and interaction of collapsin response mediator protein 5 (CRMP5) and spastin in oocytes. CRMP5 can provide structural support and promote microtubule aggregation, creating transportation routes, and can interact with spastin in the microtubule activity of nerve cells (30). Knocking down CRMP5 may lead to spindle abnormalities and developmental disorders in oocytes. Overexpression of spastin may reverse the abnormal phenotype caused by the deletion of CRMP5. In summary, our data support a model in which the interaction between spastin and CRMP5 promotes the assembly of spindle microtubules in oocytes by controlling microtubule dynamics, therefore ensuring normal meiosis.

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Comparison of mechanisms of kinetochore capture with varying number of spindle microtubules

Physical Review Research ◽

10.1103/physrevresearch.2.013114 ◽

2020 ◽

Vol 2 (1) ◽

Cited By ~ 6

Author(s):

Indrani Nayak ◽

Dibyendu Das ◽

Amitabha Nandi

Keyword(s):

Spindle Microtubules

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Paired arrangement of kinetochores together with microtubule pivoting and dynamics drive kinetochore capture in meiosis I

Scientific Reports ◽

10.1038/srep25736 ◽

2016 ◽

Vol 6 (1) ◽

Cited By ~ 10

Author(s):

Gheorghe Cojoc ◽

Ana-Maria Florescu ◽

Alexander Krull ◽

Anna H. Klemm ◽

Nenad Pavin ◽

...

Keyword(s):

Cell Division ◽

Fission Yeast ◽

General Feature ◽

Protein Complexes ◽

Spindle Pole ◽

Single Object ◽

Homologous Chromosomes ◽

Angular Movement ◽

Spindle Microtubules ◽

Meiosis I

Abstract Kinetochores are protein complexes on the chromosomes, whose function as linkers between spindle microtubules and chromosomes is crucial for proper cell division. The mechanisms that facilitate kinetochore capture by microtubules are still unclear. In the present study, we combine experiments and theory to explore the mechanisms of kinetochore capture at the onset of meiosis I in fission yeast. We show that kinetochores on homologous chromosomes move together, microtubules are dynamic and pivot around the spindle pole, and the average capture time is 3–4 minutes. Our theory describes paired kinetochores on homologous chromosomes as a single object, as well as angular movement of microtubules and their dynamics. For the experimentally measured parameters, the model reproduces the measured capture kinetics and shows that the paired configuration of kinetochores accelerates capture, whereas microtubule pivoting and dynamics have a smaller contribution. Kinetochore pairing may be a general feature that increases capture efficiency in meiotic cells.

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Modulated targeting of GFP-AtMAP65-1 to central spindle microtubules during division

The Plant Journal ◽

10.1111/j.1365-313x.2005.02464.x ◽

2005 ◽

Vol 43 (4) ◽

pp. 469-478 ◽

Cited By ~ 36

Author(s):

Guojie Mao ◽

Jordi Chan ◽

Grant Calder ◽

John H. Doonan ◽

Clive W. Lloyd

Keyword(s):

Central Spindle ◽

Spindle Microtubules

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Fyn Accelerates M Phase Progression by Promoting the Assembly of Mitotic Spindle Microtubules

Journal of Cellular Biochemistry ◽

10.1002/jcb.25373 ◽

2015 ◽

Vol 117 (4) ◽

pp. 894-903 ◽

Cited By ~ 10

Author(s):

Mai Okamoto ◽

Yuji Nakayama ◽

Ayana Kakihana ◽

Ryuzaburo Yuki ◽

Noritaka Yamaguchi ◽

...

Keyword(s):

Mitotic Spindle ◽

M Phase ◽

Phase Progression ◽

Spindle Microtubules

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Lateral association and elongation of vimentin intermediate filament proteins: A time-resolved light-scattering study

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1606372113 ◽

2016 ◽

Vol 113 (40) ◽

pp. 11152-11157 ◽

Cited By ~ 12

Author(s):

Carlos G. Lopez ◽

Oliva Saldanha ◽

Klaus Huber ◽

Sarah Köster

Keyword(s):

Light Scattering ◽

Quantitative Model ◽

Radius Of Gyration ◽

Time Resolved ◽

Intermediate Filament Proteins ◽

Hierarchical Assembly ◽

Lateral Association ◽

Cytoskeletal Filament ◽

Longitudinal Association ◽

Scattering Study

Vimentin intermediate filaments (IFs) are part of a family of proteins that constitute one of the three filament systems in the cytoskeleton, a major contributor to cell mechanics. One property that distinguishes IFs from the other cytoskeletal filament types, actin filaments and microtubules, is their highly hierarchical assembly pathway, where a lateral association step is followed by elongation. Here we present an innovative technique to follow the elongation reaction in solution and in situ by time-resolved static and dynamic light scattering, thereby precisely capturing the relevant time and length scales of seconds to minutes and 60–600 nm, respectively. We apply a quantitative model to our data and succeed in consistently describing the entire set of data, including particle mass, radius of gyration, and hydrodynamic radius during longitudinal association.

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SEQUENCES IN THE FORMATION OF CLOTS FROM PURIFIED BOVINE FIBRINOGEN AND THROMBIN: A STUDY WITH THE ELECTRON MICROSCOPE

Journal of Experimental Medicine ◽

10.1084/jem.90.3.225 ◽

1949 ◽

Vol 90 (3) ◽

pp. 225-232 ◽

Cited By ~ 63

Author(s):

Keith R. Porter ◽

Clinton Van Zandt Hawn

Keyword(s):

Electron Microscope ◽

Electron Micrographs ◽

X Ray Diffraction ◽

X Ray ◽

Physical Constants ◽

Lateral Association ◽

Fibrinogen Molecule

The observed sequences in the formation of clots from purified bovine fibrinogen and thrombin are described. Under the conditions of these experiments, it appears that fibrinogen molecules are polymerized by the action of thrombin to form needle-shaped, crystal-like protofibrils which then become aligned into fiber strands by lateral association. The integrity of the unit fibrils is maintained within the strand. A model of the fibrinogen molecule is proposed which may satisfy the reported physical constants, data from x-ray diffraction studies, and observations made upon electron micrographs.

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Meiosis in Coprinus Lagopus: A Comparative Study with Light and Electron Microscopy

Journal of Cell Science ◽

10.1242/jcs.2.4.529 ◽

1967 ◽

Vol 2 (4) ◽

pp. 529-536

Author(s):

B. C. LU

Keyword(s):

Nuclear Fusion ◽

Light And Electron Microscopy ◽

Central Component ◽

Fruiting Bodies ◽

Homologous Pairing ◽

Animal Cells ◽

Characteristic Structure ◽

Homologous Chromosomes ◽

Central Spindle ◽

Spindle Microtubules

Meiosis within fruiting bodies of Coprinus lagopus Fr. is closely synchronized. This conveniently facilitates joint light- and electron-microscope observations. Before nuclear fusion the chromatin appears diffuse in the light microscope; after nuclear fusion individual chromosomes can be recognized. In the electron micrographs the chromatin of pre-fusion and early fusion nuclei cannot be recognized as defined structures with the fixation and staining procedures employed. At the time of synapsis the lateral components of the synaptinemal complexes can be seen in the micrographs. The pairing process of the two chromosomes of the homologous pairs is believed to involve two steps: (1) two homologous chromosomes become aligned in parallel, and (2) pairing occurs by formation of the synaptinemal complex including the central synaptic component. The term synaptic centre is coined for the central component, which is believed to be the zone where crossing-over occurs. The formation of this structure in relation to homologous pairing, and the structural organization of the synaptinemal complexes are discussed. At meiotic metaphase, the chromosomes congregate around the central spindle microtubules. They are contracted and contain densely packed chromatin fibrils. Two types of spindle microtubules are demonstrated: (1) the chromosomal microtubules directly connecting the chromosomes to the centrosomes, and (2) the central spindle microtubules connecting the two centrosomes. The centrosomes are round, fibril-containing bodies approximately 0.3 µ in diameter. They have been observed outside the nuclear envelope at pachytene, but do not show the characteristic structure normally found in animal cells.

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