The Legacy from the Oocyte and its Role in Controlling Early Development of the Mouse Embryo

Pratt, Hester P. M.; Bolton, Virginia N.; Gudgeon, Katy A.

doi:10.1002/9780470720790.ch12

Cited by 21 publications

(4 citation statements)

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“…Importantly, CycT1 and CycT2 mRNA species were found in the fully grown egg, but not in the two-cell embryo. Since, substantial amounts of stored RNA are destroyed shortly after fertilization (12,26), it is likely that CycT1 and CycT2 transcripts are also lost at this stage. However, the expression of these cyclins must commence soon thereafter, as S2 in the CTD of RNAPII is heavily phosphorylated during zygotic gene activation, when transcription becomes a requirement for further development (4).…”

Section: Discussionmentioning

confidence: 99%

Cyclin T2 Is Essential for Mouse Embryogenesis

Kohoutek

Blažek

et al. 2009

Molecular and Cellular Biology

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The positive transcription elongation factor b (P-TEFb) is essential for the elongation of transcription and cotranscriptional processing by RNA polymerase II. In mammals, it contains predominantly the C-type cyclin cyclin T1 (CycT1) or CycT2 and cyclin-dependent kinase 9 (Cdk9). To determine if these cyclins have redundant functions or affect distinct sets of genes, we genetically inactivated the CycT2 gene (Ccnt2) using the ␤-galactosidase-neomycin gene (␤-geo) gene trap technology in the mouse. Visualizing ␤-galactosidase during mouse embryogenesis revealed that CycT2 is expressed abundantly during embryogenesis and throughout the organism in the adult. This finding was reflected in the expression of CycT2 in all adult tissues and organs. However, despite numerous matings of heterozygous mice, we observed no CycT2 ؊/؊ embryos, pups, or adult mice. This early lethality could have resulted from decreased expression of critical genes, which were revealed by short interfering RNAs against CycT2 in embryonic stem cells. Thus, CycT1 and CycT2 are not redundant, and these different P-TEFb complexes regulate subsets of distinct genes that are important for embryonic development.Eukaryotic transcription by RNA polymerase II (RNAPII) is regulated at several distinct steps, which include initiation, promoter clearance, elongation, and cotranscriptional processing of primary transcripts (19,25,27). Of these, elongation is regulated by the positive transcription elongation factor b (PTEFb), which contains predominantly the C-type cyclin cyclin T1 (CycT1) or CycT2 and cyclin-dependent kinase 9 (Cdk9). All these different P-TEFb complexes phosphorylate serines at position 2 (S2) in the C-terminal domain (CTD) of RNAPII, as well as components of the negative transcription elongation factor, which contains minimally the DRB (5,6-dichloro-1-␤- D-ribofuranosylbenzimidazole) sensitivity-inducing factor (DSIF) and the negative elongation factor. These posttranslational modifications exchange basal transcription factors for splicing and polyadenylation machineries on RNAPII, as well as modify DSIF for productive elongation (25).Although these P-TEFb complexes can phosphorylate the CTD and lead to transcriptional elongation when recruited to RNAPII via heterologous nucleic acid-tethering systems, it is not clear whether they have redundant or unique functions in cells (18,33). Thus far, CycT1, which is the most abundant of these cyclins, has been implicated as the coactivator of the transcriptional transactivator Tat from human immunodeficiency virus, RelA from NF-B, class II transactivator, the protooncogene c-myc, several members of the steroid hormone receptor family, and the autoimmune regulator AIRE (3, 8, 14-16, 24, 29, 36). Moreover, Runx1, which is the active repressor of CD4 expression in double-negative thymocytes, decoys CycT1 away from the CD4 promoter, thus keeping the

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Section: Discussionmentioning

confidence: 99%

Cyclin T2 Is Essential for Mouse Embryogenesis

Kohoutek

Blažek

et al. 2009

Molecular and Cellular Biology

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“…mRNAs and proteins accumulated during growth phase of GV oocyte i.e. during the long arrest in the prophase of the first meiotic division (Bachvarova and De Leon, 1980;Pratt et al, 1983;Bachvarova, 1985;Nothias et al, 1995). The intense transcription ceases once oocyte reaches its maximal volume and becomes competent to resume meiotic division (Zuccotti et al, 1995;Bouniol-Baly et al, 1999;De La Fuente, 2006).…”

Section: First Embryonic Mitosis: Meiosis-like Mitosis or How And Whmentioning

confidence: 99%

On the transition from the meiotic to mitotic cell cycle during early mouse development

Kubiak

Ciemerych²,

Hupalowska³

et al. 2008

Int. J. Dev. Biol.

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Here, we outline the mechanisms involved in the regulation of cell divisions during oocyte maturation and early cleavages of the mouse embryo. Our interest is focused on the regulation of meiotic M-phases and the first embryonic mitoses that are differently tuned and are characterized by specifically modified mechanisms, some of which have been recently identified. The transitions between the M-phases during this period of development, as well as associated changes in their regulation, are of key importance for both the meiotic maturation of oocytes and the further development of the mammalian embryo. The mouse is an excellent model for studies of the cell cycle during oogenesis and early development. Nevertheless, a number of molecular mechanisms described here were discovered or confirmed during the study of other species and apply also to other mammals including humans. KEY WORDS: meiosis, mitosis, oocyte, embryo, MPF, CSF, spindle assembly checkpoint, Mad2, Rec8Cell cycle is often modified in different cell types during development and aging of the individual. These adaptations seem to be of a particular importance for the success of the early developmental program. The cell cycle must be modified during meiosis, when DNA replication is suppressed, during spermatogenesis in males and in oocytes undergoing the process of meiotic maturation in females. The oocyte enters the first meiotic prophase that can take several years. Then, in sexually mature females, the oocyte resumes meiosis and progress through two M-phases of the meiotic maturation, each of them differently regulated, to assure correct separation of maternal chromatin. Fertilized egg transits from meiotic to the mitotic cell cycle and resume DNA replication.In the current review we will focus on M-phase modifications that are the subject of the research in our laboratories. We choose three examples of specific M-phase adjustments i.e. metaphase I, and metaphase II of oocyte meiotic divisions and the first mitosis of mouse embryo. We center our attention on the temporal regulation of metaphase I progression and the singularities of the spindle assembly checkpoint during this period, mechanisms of sustaining and exiting metaphase II-arrest, and finally the unique regulation of the first embryonic mitosis. The correct timing of Int.

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“…The role, if any, of the remaining RNAs [20], which are still detectable at the blastocyst stage both in the trophoblast and inner cell mass [20], remains unknown. Similarly, most of the proteins synthesized before transcriptional activation of the embryonic genome have apparently a long half-life [21] and some remain detectable until the morula stage [22,23]. There is some evidence that a subset of proteins derived from the ovum cytoplasm are differentially regulated and subjected to posttranslational modifications [24], but their involvement in an intrinsic developmental program remains speculative.…”

Section: Discussionmentioning

confidence: 99%

The expression of reference genes affecting preimplantation mouse embryo death in the DDK syndrome

Song

BaoGuo

et al. 2011

2011 International Conference on Remote Sensing, Environment and Transportation Engineering

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The DDK syndrome is known as the polar-lethal embryonic death that occurs at the morula-blastocyst stage when female mice of the DDK strain are mated with males from many other inbred strains (alien males). Embryonic death is interpreted to be caused by incompatibility between a DDK oocyte factor and the product from male pronucleus, both of which map to the Om locus on mouse chromosome 11. We compared development of DDK ×DDK embryos (high viability) and DDK × BALB/c embryos (low viability) before the morula stage (as 2 cell, 4 cell and 8 cell), there was no any morphological manifestations of DDK syndrome are observed. To make sure if the transcripts that are differentially in the DDK ×BALB/c embryos, we selected a series reference genes such as proto-oncogenes, growth factors, and growth and apoptosis genes and confirmed by quantitative RT-PCR that numbers of genes in those stages are down regulated in the DDK ×BALB/c embryos. However, except the LIF (leukemia inhibitory factor) was negative expressed and the other genes all detected in three stages. The expression of EGF (epidermal growth factor), EGF-R (epidermal growth factor receptor), Bcl-2 were significant variations (P< 0.01) at the early 4 cell and 8 cell stage, and also the test was significant variations (P<0.01) for the Mcl-1 at all the three stages. Our results indicate that the Om was effected the low-expression of functional genes indirectly to induce embryos destined to die of DDK syndrome and that the embryonic death observed is result of the regulation of multiple genes. Keywords-mouse eimplantation embry; polar-lethal embryonic death; ovum mutant or Om; DDK syndrome I.978-1-4244-9171-1/11/$26.00 ©2011 IEEE

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The Legacy from the Oocyte and its Role in Controlling Early Development of the Mouse Embryo

Cited by 21 publications

References 29 publications

Cyclin T2 Is Essential for Mouse Embryogenesis

Cyclin T2 Is Essential for Mouse Embryogenesis

On the transition from the meiotic to mitotic cell cycle during early mouse development

The expression of reference genes affecting preimplantation mouse embryo death in the DDK syndrome

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