Cyclin CYB-3 controls both S-phase and mitosis and is asymmetrically distributed in the early <i>C. elegans</i> embryo

Michael, W. Matthew

doi:10.1242/jcs.197087

Cited by 3 publications

(4 citation statements)

References 22 publications

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“…). The effect of PAR‐4/PAR‐1 is mediated by a specific isoform of Cyclin B that has a non‐canonical role in promoting S‐phase progression (Michael ). These mechanisms provide lineage‐specific regulations of cell‐cycle duration independently of the cell size.…”

Section: The Nucleo‐cytoplasmic (N/c) Ratio and The Asynchrony Of Mitmentioning

confidence: 99%

Emerging mechanisms regulating mitotic synchrony during animal embryogenesis

Ogura

Sasakura

2017

Dev Growth Differ

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The basic mechanisms controlling mitosis are highly conserved in animals regardless of cell types and developmental stages. However, an exceptional aspect of mitosis is seen during early animal embryogenesis in which a large fertilized egg is quickly divided into smaller blastomeres according to the reproducible spatiotemporal pattern that does not rely on the cell-cycle arrest or growth. This mitosis, referred to as cleavage, overlaps in the timeframe with the specification of cell fate. The precise spatiotemporal regulation of cleavages is therefore essential to the creation of the appropriate cell number and to the morphology of an embryo. To achieve the reproducibility of cleavage during embryogenesis, the relative timing of mitosis between cells, which we refer to as synchrony, must be properly regulated. Studies in model organisms have begun to reveal how the synchrony of mitosis is regulated by the developmental modulation of cell-cycle machineries. In this review, we focus on three such mechanisms: biochemical switches that achieve the synchrony of mitosis, the nucleo-cytoplasmic ratio that provokes the asynchrony of mitosis, and the transcriptional mechanisms coupled with cell fate control that reestablish the synchrony of mitosis in each fate-restricted compartment. Our review is an attempt to understand the temporal patterns of cleavages in animal embryos created by the combinations of these three mechanisms.

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Section: The Nucleo‐cytoplasmic (N/c) Ratio and The Asynchrony Of Mitmentioning

confidence: 99%

Emerging mechanisms regulating mitotic synchrony during animal embryogenesis

Ogura

Sasakura

2017

Dev Growth Differ

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“…A growing consensus from loss-of-function analyzes indicates an anaphase promoting role of Cyclin B3 [16][17][18]26,56]. Some recent evidence that Cyclin B3 regulates timely progression of S-phase and NEBD, might imply that anaphase defects observed in Cyclin B3 mutants may be indirectly caused by under-replicated chromosomes in the preceding S-phase [19]. In mitotic C. elegans embryonic cells, this anaphase-promoting activity appears to be SAC-dependent [56], whereas in meiotic mouse oocytes, Cyclin B3 regulation of the metaphase-anaphase transition is proposed to operate through a SAC-independent pathway [26].…”

Section: Discussionmentioning

confidence: 99%

“…In both meiosis and mitosis CYB-1 is required for chromosome congression, and CYB-3 is required for chromosome segregation [18]. CYB-3 also supports S-phase progression and is a major contributor to promote NEBD in mitotic entry [19]. In higher vertebrates, where the cyst phase is resolved very early in oogenesis, Cyclin B1 is essential, while Cyclin B2 is dispensable [20,21].…”

Section: Introductionmentioning

confidence: 99%

Specialization of CDK1 and cyclin B paralog functions in a coenocystic mode of oogenic meiosis

Feng

Thompson

2018

Cell Cycle

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Oogenesis in the urochordate, Oikopleura dioica, occurs in a large coenocyst in which vitellogenesis precedes oocyte selection in order to adapt oocyte production to nutrient conditions. The animal has expanded Cyclin-Dependant Kinase 1 (CDK1) and Cyclin B paralog complements, with several expressed during oogenesis. Here, we addressed functional redundancy and specialization of CDK1 and cyclin B paralogs during oogenesis and early embryogenesis through spatiotemporal analyses and knockdown assays. CDK1a translocated from organizing centres (OCs) to selected meiotic nuclei at the beginning of the P4 phase of oogenesis, and its knockdown impaired vitellogenesis, nurse nuclear dumping, and entry of nurse nuclei into apoptosis. CDK1d-Cyclin Ba translocated from OCs to selected meiotic nuclei in P4, drove meiosis resumption and promoted nuclear envelope breakdown (NEBD). CDK1d-Cyclin Ba was also involved in histone H3S28 phosphorylation on centromeres and meiotic spindle assembly through regulating Aurora B localization to centromeres during prometaphase I. In other studied species, Cyclin B3 commonly promotes anaphase entry, but we found O. dioica Cyclin B3a to be non-essential for anaphase entry during oogenic meiosis. Instead, Cyclin B3a contributed to meiotic spindle assembly though its loss could be compensated by Cyclin Ba.

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“…Most of these nuclei form abundant OLLAS::RPA-1 and FLAG::RPA-2 foci co-localizing with chromosomes (DAPI) which appear as a "haze" or "coating" on the DNA. To determine if this RPA localization pattern is associated with S-phase nuclei, we co-stained for FLAG::RPA-2 and PCN-1 (PCNA homolog, clamp subunit associated with DNA polymerase during replication, (42,43)) . PCN-1 is found in S-phase nuclei in a similar localization pattern to that of RPA-1 and RPA-2, and all nuclei that expressed PCN-1 staining also stained for FLAG::RPA-2 ( Figure 1D).…”

Section: Introductionmentioning

confidence: 99%

RPA complexes inCaenorhabditis elegansmeiosis; unique roles in replication, meiotic recombination and apoptosis

Hefel

Cronin

Harrel

et al. 2020

Preprint

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Replication Protein A (RPA) is critical complex that acts in replication and promotes homologous recombination by allowing recombinase recruitment to processed DSB ends. Most organisms possess three RPA subunits (RPA1, RPA2, RPA3) that form a trimeric complex critical for viability. The Caenorhabditis elegans genome encodes for RPA-1, RPA-2 and an RPA-2 paralog RPA-4. In our analysis, we determine that RPA-2 is critical for germline replication, and normal repair of meiotic DSBs. Interestingly, RPA-1 but not RPA-2 is essential for replication, contradictory to what is seen in other organisms, that require both subunits. In the germline, both RPA-1/2 and RPA-1/4 complexes form, but RPA-1/4 is less abundant and its formation is repressed by RPA-2. While RPA-4 does not participate in replication or recombination, we find that RPA-4 inhibit RAD-51 filament formation and promotes apoptosis on a subset of damaged nuclei. Altogether these findings point to sub-functionalization and antagonistic roles of RPA complexes in C. elegans. Replication protein A (RPA) is a heterotrimeric complex which binds single-stranded DNA (ssDNA) with high affinity (reviewed in (1). In most organisms, this complex consists of a large (70 kDa), medium (32 kDa), and small (14 kDa) subunit (RPA1, RPA2, and RPA3 respectively in humans), each of which contains at least one oligosaccharide binding domain (OB fold), which gives the complex its ssDNA binding activity (1). RPA removes secondary structures in ssDNA, a property which is critical for replication and recombination (2). RPA was originally isolated as a factor that was essential for human simian virus SV40 in vivo replication (3). The role of RPA in replication is not only driven by its ability to bind ssDNA, but also through indirect interaction with proteins that are part of the replication machinery, including PCNA (4) and pol α (5). RPA also plays a role in cell cycle signaling and the DNA damage response, where RPA promotes ATM activation, possibly through its interaction with the MRN complex (reviewed in (6)), and ATR activation (7). In humans, the DNA damage induced apoptotic response is stimulated by RPA2 hyperphosphorylation (8). Furthermore, double-strand DNA break repair by homologous recombination (HR) also requires RPA, which involves its ssDNA binding property that is required for the assembly of the Rad51-ssDNA filament (reviewed in (9)). RPA is also required for other forms of DNA repair where ssDNA is formed (10). This complex is found in all eukaryotes, and the properties of the RPA complex appear to be conserved.Not all organisms contain only the three canonical RPA subunits, and in some organisms, paralogs are found. Subunit paralog identities vary between organisms, and is driven by gene duplication events throughout evolution (11). The paralogs studied frequently retain the ancestral activities of the RPA subunit or lose some activities, but seldom neofunctionalise. For example, an RPA2 paralog, RPA4 is found in several mammals. In humans, RPA4 shares some activities...

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Cyclin CYB-3 controls both S-phase and mitosis and is asymmetrically distributed in the early C. elegans embryo

Cited by 3 publications

References 22 publications

Emerging mechanisms regulating mitotic synchrony during animal embryogenesis

Emerging mechanisms regulating mitotic synchrony during animal embryogenesis

Specialization of CDK1 and cyclin B paralog functions in a coenocystic mode of oogenic meiosis

RPA complexes inCaenorhabditis elegansmeiosis; unique roles in replication, meiotic recombination and apoptosis

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