Ran in Mitosis

Gruß, Oliver J.

doi:10.1007/978-3-319-07761-1_7

Cited by 2 publications

(4 citation statements)

References 145 publications

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“…Beyond TPX2 and NuMA, numerous proteins have been identified in Xenopus egg extracts, which are under the control of RanGTP and importins, including the microtubule associated proteins HURP (hepatoma upregulated protein) and NuSAP (nucleolar spindle associated protein), the chromatin remodelling proteins ISWI and KANSL1/3, the RNA binding protein Rae1 and the nuclear pore complex (NPC) component Mel-28/ELYS. Consistently, all these proteins remain nuclear in interphase but perform key functions in M-phase in microtubule nucleation, microtubule organisation, spindle pole formation and anaphase spindle stability [ 70 , 71 , 72 , 73 ].…”

Section: The Role Of Rangtp In Meiotic Spindle Formationmentioning

confidence: 99%

“…It activates ISWI, which stabilises microtubules only after the metaphase-to-anaphase-transition to allow proper chromosome segregation [ 110 ]. ISWI helps microtubules to remain stable during anaphase [ 70 ], while two specific subunits of the chromatin remodelling complex NSL (non specific lethal), KANSL1 and 3, dissociate from chromatin already before metaphase-to-anaphase-transition to stabilise microtubule minus ends [ 73 ].…”

Section: The Mechanism Of Spindle Organization Without Centrosomesmentioning

confidence: 99%

“…Localised RanGTP production on chromatin together with delocalised Ran’s GTP hydrolysis in the mitotic cytoplasm result in a soluble gradient of RanGTP with the highest concentration next to chromatin. This explains how Ran downstream activities involved in spindle formation in M-phase become activated only in the vicinity of chromatin [ 70 , 115 , 116 ], Figure 4 . Experiments in Xenopus egg extracts documented how this gradient could be further sharpened: Cytosolic RanBP1, phosphorylated in M-phase on a single Serine residue (S60), forms a complex with Ran and RCC1, which inhibits the cytosolic activity of the latter and restrains cytosolic RanGTP production [ 117 ].…”

Section: The Mechanism Of Spindle Organization Without Centrosomesmentioning

confidence: 99%

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Animal Female Meiosis: The Challenges of Eliminating Centrosomes

Gruß

2018

Cells

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Sexual reproduction requires the generation of gametes, which are highly specialised for fertilisation. Female reproductive cells, oocytes, grow up to large sizes when they accumulate energy stocks and store proteins as well as mRNAs to enable rapid cell divisions after fertilisation. At the same time, metazoan oocytes eliminate their centrosomes, i.e., major microtubule-organizing centres (MTOCs), during or right after the long growth phases. Centrosome elimination poses two key questions: first, how can the centrosome be re-established after fertilisation? In general, metazoan oocytes exploit sperm components, i.e., the basal body of the sperm flagellum, as a platform to reinitiate centrosome production. Second, how do most metazoan oocytes manage to build up meiotic spindles without centrosomes? Oocytes have evolved mechanisms to assemble bipolar spindles solely around their chromosomes without the guidance of pre-formed MTOCs. Female animal meiosis involves microtubule nucleation and organisation into bipolar microtubule arrays in regulated self-assembly under the control of the Ran system and nuclear transport receptors. This review summarises our current understanding of the molecular mechanism underlying self-assembly of meiotic spindles, its spatio-temporal regulation, and the key players governing this process in animal oocytes.

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Section: The Role Of Rangtp In Meiotic Spindle Formationmentioning

confidence: 99%

Section: The Mechanism Of Spindle Organization Without Centrosomesmentioning

confidence: 99%

Section: The Mechanism Of Spindle Organization Without Centrosomesmentioning

confidence: 99%

See 1 more Smart Citation

Animal Female Meiosis: The Challenges of Eliminating Centrosomes

Gruß

2018

Cells

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“…[82][83][84] The prevailing model is that meiotic and mitotic chromosomes retain the activity of the G-nucleotide exchange factor for Ran, Rcc1, on chromatin, and keep on producing RanGTP during meiosis or mitosis. This results in high RanGTP levels and active microtubule assembly factors next to chromatin [85][86][87][88] (Figure 5). Of note, the mechanisms of meiosis I in mouse oocytes may be even different as it occurs not only in the absence of centrioles but also tolerates reduced RanGTP levels.…”

Section: Spindle Formation In the Absence Of Centriolesmentioning

confidence: 99%

Loss and Rebirth of the Animal Microtubule Organizing Center: How Maternal Expression of Centrosomal Proteins Cooperates with the Sperm Centriole in Zygotic Centrosome Reformation

2018

Self Cite

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Centrosomes are the main microtubule organizing centers in animal cells. In particular during embryogenesis, they ensure faithful spindle formation and proper cell divisions. As metazoan centrosomes are eliminated during oogenesis, they have to be reassembled upon fertilization. Most metazoans use the sperm centrioles as templates for new centrosome biogenesis while the egg's cytoplasm re-prepares all components for on-going centrosome duplication in rapidly dividing embryonic cells. We discuss our knowledge and the experimental challenges to analyze zygotic centrosome reformation, which requires genetic experiments to enable scrutinizing respective male and female contributions. Male and female knockout animals and mRNA injection to mimic maternal expression of centrosomal proteins could point a way to the systematic molecular dissection of the process. The most recent data suggest that timely expression of centrosome components in oocytes is the key to zygotic centrosome reformation that uses male sperm as coordinators for de novo centrosome production.

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Ran in Mitosis

Cited by 2 publications

References 145 publications

Animal Female Meiosis: The Challenges of Eliminating Centrosomes

Animal Female Meiosis: The Challenges of Eliminating Centrosomes

Loss and Rebirth of the Animal Microtubule Organizing Center: How Maternal Expression of Centrosomal Proteins Cooperates with the Sperm Centriole in Zygotic Centrosome Reformation

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