Separation and Loss of Centrioles From Primordidal Germ Cells to Mature Oocytes in the Mouse

AbstractOocytes, including those from mammals, lack centrioles, but neither the mechanism by which mature eggs lose their centrioles nor the exact stage at which centrioles are destroyed during oogenesis is known. To answer questions raised by centriole disappearance during oogenesis, using a transgenic mouse expressing GFP-centrin-2 (GFP CETN2), we traced their presence from e11.5 primordial germ cells (PGCs) through oogenesis and their ultimate dissolution in mature oocytes. We show tightly coupled CETN2 doublets in PGCs, oogonia, and pre-pubertal oocytes. Beginning with follicular recruitment of incompetent germinal vesicle (GV) oocytes, through full oocyte maturation, the CETN2 doublets separate within the pericentriolar material (PCM); concomitantly, a rise in single CETN2 pairs is identified. CETN2 dissolution accelerates following meiosis resumption. Remarkably, a single CETN2 pair is retained in the PCM of most meiotic metaphase-I and -II spindle poles. Partial dissolution of the CETN2 foci occurs even as other centriole markers, like Cep135, a protein necessary for centriole duplication, are maintained at the PCM. Furthermore, live imaging demonstrates that the link between the two centrioles breaks as meiosis resumes and that centriole association with the PCM is progressively lost. Microtubule inhibition shows that centriole dissolution is uncoupled from microtubule dynamics. Thus, centriole doublets, present in early G2-arrested meiotic prophase oocytes, begin partial reduction during follicular recruitment and meiotic resumption, much later than previously thought.

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TRIM37 prevents formation of condensate-organized ectopic spindle poles to ensure mitotic fidelity

The Journal of Cell Biology ◽

10.1083/jcb.202010180 ◽

2021 ◽

Vol 220 (7) ◽

Author(s):

Franz Meitinger ◽

Dong Kong ◽

Midori Ohta ◽

Arshad Desai ◽

Karen Oegema ◽

...

Keyword(s):

Chromosome Segregation ◽

Ubiquitin Ligase ◽

Spindle Pole ◽

Mitotic Entry ◽

Centriole Duplication ◽

Mulibrey Nanism ◽

Spindle Poles ◽

Pathological Mechanism ◽

Pericentriolar Material ◽

Centrosomal Proteins

Centrosomes are composed of a centriolar core surrounded by pericentriolar material that nucleates microtubules. The ubiquitin ligase TRIM37 localizes to centrosomes, but its centrosomal roles are not yet defined. We show that TRIM37 does not control centriole duplication, structure, or the ability of centrioles to form cilia but instead prevents assembly of an ectopic centrobin-scaffolded structured condensate that forms by budding off of centrosomes. In ∼25% of TRIM37-deficient cells, the condensate organizes an ectopic spindle pole, recruiting other centrosomal proteins and acquiring microtubule nucleation capacity during mitotic entry. Ectopic spindle pole–associated transient multipolarity and multipolar segregation in TRIM37-deficient cells are suppressed by removing centrobin, which interacts with and is ubiquitinated by TRIM37. Thus, TRIM37 ensures accurate chromosome segregation by preventing the formation of centrobin-scaffolded condensates that organize ectopic spindle poles. Mutations in TRIM37 cause the disorder mulibrey nanism, and patient-derived cells harbor centrobin condensate-organized ectopic poles, leading us to propose that chromosome missegregation is a pathological mechanism in this disorder.

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Centriole number and the reproductive capacity of spindle poles.

The Journal of Cell Biology ◽

10.1083/jcb.100.3.887 ◽

1985 ◽

Vol 100 (3) ◽

pp. 887-896 ◽

Cited By ~ 111

Author(s):

G Sluder ◽

C L Rieder

Keyword(s):

Spindle Pole ◽

Reproductive Capacity ◽

Centriole Duplication ◽

Voltage Electron ◽

Spindle Poles ◽

Mother And Daughter ◽

Pericentriolar Material ◽

History Of ◽

Bipolar Spindles

The reproduction of spindle poles is a key event in the cell's preparation for mitosis. To gain further insight into how this process is controlled, we systematically characterized the ultrastructure of spindle poles whose reproductive capacity had been experimentally altered. In particular, we wanted to determine if the ability of a pole to reproduce before the next division is related to the number of centrioles it contains. We used mercaptoethanol to indirectly induce the formation of monopolar spindles in sea urchin eggs. We followed individually treated eggs in vivo with a polarizing microscope during the induction and development of monopolar spindles. We then fixed each egg at one of three predetermined key stages and serially semithick sectioned it for observation in a high-voltage electron microscope. We thus know the history of each egg before fixation and, from earlier studies, what that cell would have done had it not been fixed. We found that spindle poles that would have given rise to monopolar spindles at the next mitosis have only one centriole whereas spindle poles that would have formed bipolar spindles at the next division have two centrioles. By serially sectioning each egg, we were able to count all centrioles present. In the twelve cells examined, we found no cases of acentriolar spindle poles or centriole reduplication. Thus, the reproductive capacity of a spindle pole is linked to the number of centrioles it contains. Our experimental results also show, contrary to existing reports, that the daughter centriole of a centrosome can acquire pericentriolar material without first becoming a parent. Furthermore, our results demonstrate that the splitting apart of mother and daughter centrioles is an event that is distinct from, and not dependent on, centriole duplication.

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mRNA translation during oocyte maturation plays a key role in development of primordial germ cells inXenopus embryos

Journal of Biosciences ◽

10.1007/bf02702618 ◽

2004 ◽

Vol 29 (3) ◽

pp. 355-358

Author(s):

Bahman Zeynali ◽

Keith E Dixon

Keyword(s):

Oocyte Maturation ◽

Germ Cells ◽

Primordial Germ Cells ◽

Mrna Translation

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Effects of genistein and genistin on in vitro maturation of pig oocytes

Czech Journal of Animal Science ◽

10.17221/2718-cjas ◽

2008 ◽

Vol 53 (No. 1) ◽

pp. 1-8 ◽

Cited By ~ 3

Author(s):

Z. Vodková ◽

R. Rajmon ◽

J. Petr ◽

P. Klabanová ◽

F. Jílek

Keyword(s):

Protein Kinase ◽

Oocyte Maturation ◽

Cell Expansion ◽

Estrogenic Activity ◽

Germinal Vesicle ◽

Meiotic Metaphase ◽

Tyrosine Protein Kinase ◽

Pig Oocyte ◽

Different Doses

The objective of the study was to verify the hypothesis that GEN (genistein – phytoestrogen and an inhibitor of tyrosine protein kinase – TPK) effects on pig oocyte maturation and cumular cell expansion under <I>in vitro</I> conditions are connected with its estrogenic activity. Oocytes were cultivated for 24 hours up to the stage of the first meiotic metaphase (MI). Three different doses of GEN (13, 40, 80 µg/ml of medium) and also three doses of GIN, genistin, an analogue of GEN without effects on TPK, (80, 160 and 240 µg/ml of medium) were tested. To verify the reversibility of GEN effects, the oocytes were first cultivated for 24 hours with 80 µg of GEN per 1 ml of medium and then for another 24 hours without any GEN. GEN blocked pig oocyte maturation at the stage of the germinal vesicle (GV), depending on the dose. After rinsing out the GEN the oocyte maturation recovered, but with abnormalities (32%). GIN in a concentration of 80 µg/ml of medium induced a significant blockage at the GV stage (18%). With an increase in the GIN concentration, the number of oocytes blocked at the GV stage significantly decreased, but the abnormal maturation increased (up to 31%). GEN inhibited the cumular cell expansion in proportion to its dose. GIN had a less pronounced effect. As GEN and GIN effects demonstrate similar patterns, it is probable that estrogenic activity is involved.

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Hexachlorobenzene toxicity in the rat ovary: II. Ultrastructure induced by medium (10 mg/kg) dose exposure

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s042482010012374x ◽

1992 ◽

Vol 50 (1) ◽

pp. 668-669

Author(s):

Amreek Singh ◽

Warren G. Foster ◽

Anna Dykeman ◽

David C. Villeneuve

Keyword(s):

Germ Cells ◽

Primordial Germ Cells ◽

Surface Epithelium ◽

Morphological Parameters ◽

Comprehensive Investigation ◽

Ovary Surface Epithelium ◽

Rat Ovary ◽

High Doses

Hexachlorobenzene (HCB) is a known toxicant that is found in the environment as a by-product during manufacture of certain pesticides. This chlorinated chemical has been isolated from many tissues including ovary. When administered in high doses, HCB causes degeneration of primordial germ cells and ovary surface epithelium in sub-human primates. A purpose of this experiment was to determine a no-effect dose of the chemical on the rat ovary. The study is part of a comprehensive investigation on the effects of the compound on the biochemical, hematological, and morphological parameters in the monkey and rat.

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