Chk2/Cds1 protein kinase blocks apoptosis during early development of <i>Xenopus laevis</i>

Wroble, Brian N.; Sible, Jill C.

doi:10.1002/dvdy.20449

Cited by 11 publications

(20 citation statements)

References 44 publications

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“…If Chk1 was inhibited, the development was normal until the onset of gastrulation at which the embryo died, with cells entering in apoptosis. In zygotes with two blastomeres injected with SAMDL mRNAs, apoptosis was also observed at gastrulation [21,22]. If these mRNAs were injected on a side only in embryos with 4 to 8 cells, a large number of animals became tadpoles; if embryos were 16 to 32 cells, all individuals became tadpoles with sometimes abnormalities.…”

Section: Regulation Of Apoptosis During Segmentation and Gastrulationmentioning

confidence: 99%

Apoptosis in amphibian development

Exbrayat¹,

Moudilou²,

Abrouk³

et al. 2012

ABB

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Amphibians and more particularly X. laevis are models often used for studying apoptosis during embryonic development. Using several methods, searchers determined the localization of programmed cell deaths (PCD). Several experimental methods also have been used to understand the regulatory mechanisms of apoptosis, throughout development, contributing to elucidate the general action of several genes and proteins. Apoptosis occurs very early, with a first program under control of maternal genes expressed before MBT, in order to eliminate damaged cells before gastrulation, and a second program at the onset of gastrulation. PCD is also observed during neurulation. Then, apoptotic cells are observed in amphibian organogenesis and metamorphosis. Results of these researches showed both importance of PCD for embryonic development, and the complexity of its regulation. Results obtained can be useful to understand others aspects of the importance of apoptosis, particularly pathological aspects.

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Section: Regulation Of Apoptosis During Segmentation and Gastrulationmentioning

confidence: 99%

Apoptosis in amphibian development

Exbrayat¹,

Moudilou²,

Abrouk³

et al. 2012

ABB

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“…Our studies in which we microinject cytochrome c into individual blastomeres and cause entire embryo apoptosis support this idea. It is well known that checkpoint activation does not occur in embryos until after the mid-blastula transition36; one important reason for such a delay might be to prevent the triggering of apoptosis by minor cellular damage during a time when death of an individual blastomere would lead to death of the entire embryo. Conversely, in the presence of a cell-damaging stimulus sufficiently strong to warrant induction of cell death in a single cell, it would likely be advantageous to rapidly induce death of the entire embryo to avoid significant developmental anomalies.…”

Section: Discussionmentioning

confidence: 99%

Features of programmed cell death in intact Xenopus oocytes and early embryos revealed by near-infrared fluorescence and real-time monitoring

2009

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Factors influencing apoptosis of vertebrate eggs and early embryos have been studied in cell-free systems and in intact embryos by analyzing individual apoptotic regulators or caspase activation in static samples. Described here is a novel method for monitoring caspase activity in living Xenopus oocytes and early embryos. The approach, utilizing microinjection of a near-infrared caspase substrate that emits fluorescence only after its proteolytic cleavage by active effector caspases, has enabled the elucidation of otherwise cryptic aspects of apoptotic regulation. In particular, we demonstrate that brief caspase activity (ten minutes) is sufficient to cause apoptotic death in this system. We illustrate a cytochrome c dose threshold in the oocyte, which is lowered by Smac, a protein that binds thereby neutralizing inhibitor of apoptosis proteins. We show that meiotic oocytes develop resistance to cytochrome c, and that eventual death of oocytes arrested in meiosis is caspase-independent. Finally, data acquired through imaging caspase activity in the Xenopus embryo suggests that apoptosis in very early development is not cell-autonomous. These studies both validate this assay as a useful tool for apoptosis research and reveal subtleties in the cell death program during early development. Moreover, this method offers a potentially valuable screening modality for identifying novel apoptotic regulators.

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“…Thus, in this Xenopus embryonic system, SAMDC-overexpressed cells underwent apoptosis, rather than arresting cell cycles. This is interesting, since adult-type cells that happened to have DNA damages by γ-ray irradiation usually arrest cell cycles rather than undergoing apoptosis (Wroble and Sible, 2005). …”

Section: The Cell Dissociation Observed Was Due To Execution Of Apoptmentioning

confidence: 99%

“…Furthermore, onset of the cell dissociation executed by γ-ray exposure has been shown to be suppressed “partially” (the onset of the cell dissociation was postponed only by 2–3 hrs) by prior microinjection of Bcl-2 mRNA (Anderson et al 1997; Hensey and Gautier, 1997). In more recent studies on the apoptosis induced by DNA-damaging agent like γ-ray, cyclin-dependent protein kinases have been shown to play important roles to switch on the apoptosis (Finkielstein et al 2002; Carter and Sible, 2003; Carter et al 2006; Wroble and Sible, 2005). …”

Section: Various Toxic Treatments Other Than Samdc Overexpression Indmentioning

confidence: 99%

“…First, cleavage becomes asynchronous (Signoret and Lefresne, 1973; Newport and Kirschner, 1982), and cells acquire motility (Newport and Kirschner, 1982), especially in the future dorsal animal region (Minoura et al 1995). Along with these changes, cell cycles shift from checkpoint-unregulated ones to checkpoint-regulated ones (Wroble and Sible, 2005), and in this remodeling process checkpoint kinases such as Chk2/Cds1 and Xchk1 play key roles (Wroble and Sible, 2005; Carter and Sible, 2003). Also, transcription from zygotic nuclear genes, including tRNA genes (Brown and Littna, 1964, 1966; Shiokawa and Yamana, 1967; Shiokawa et al 1981a, b; Yang et al 2002; Yasuda and Schweger, 1992; Shiokawa et al 1994; Nakakura et al 1987; Shiokawa et al 1989) and exogenously-introduced genes like bacterial CAT (chloramphenicol acetyltransferase) genes (Etkin and Balcells, 1985; Shiokawa et al 1990) is greatly activated on a “per-embryo” basis, but not necessarily on a “per-cell” basis, since there is low but significant transcription of both endogenous (Nakakura et al 1987; Shiokawa et al 1989; Shiokawa et al 1994; Yang et al 2002) and exogenously-introduced (Shiokawa et al 1990) genes in preblastular embryos which are composed of relatively small number of cells.…”

Section: Introductionmentioning

confidence: 99%

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Gene Expression in Pre-MBT Embryos and Activation of Maternally-Inherited Program of Apoptosis to be Executed at around MBT as a Fail-Safe Mechanism in Xenopus Early Embryogenesis

Shiokawa

Aso²,

Kondo

et al. 2008

Gene�Regul Syst Bio

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S-adenosylmethionine decarboxylase (SAMDC) is an enzyme which converts S-adenosylmethione (SAM), a methyl donor, to decarboxylated SAM (dcSAM), an aminopropyl donor for polyamine biosynthesis. In our studies on gene expression control in Xenopus early embryogenesis, we cloned the mRNA for Xenopus SAMDC, and overexpressed the enzyme by microinjecting its mRNA into Xenopus fertilized eggs. In the mRNA-injected embryos, the level of SAMDC was enormously increased, the SAM was exhausted, and protein synthesis was greatly inhibited, but cellular polyamine content did not change appreciably. SAMDC-overexpressed embryos cleaved and developed normally up to the early blastula stage, but at the midblastula stage, or the stage of midblastula transition (MBT), all the embryos were dissociated into cells, and destroyed due to execution of apoptosis. During cleavage SAMDC-overexpressed embryos transcribed caspase-8 gene, and this was followed by activation of caspase-9. When we overexpressed p53 mRNA in fertilized eggs, similar apoptosis took place at MBT, but in this case, transcription of caspase-8 did not occur, however activation of caspase-9 took place. Apoptosis induced by SAMDC-overexpression was completely suppressed by Bcl-2, whereas apoptosis induced by p53 overexpression or treatments with other toxic agents was only partially rescued. When we injected SAMDC mRNA into only one blastomere of 8- to 32-celled embryos, descendant cells of the mRNA-injected blastomere were segregated into the blastocoel and underwent apoptosis within the blastocoel, although such embryos continued to develop and became tadpoles with various extents of anomaly, reflecting the developmental fate of the eliminated cells. Thus, embryonic cells appear to check themselves at MBT and if physiologically severely-damaged cells occur, they are eliminated from the embryo by activation and execution of the maternally-inherited program of apoptosis. We assume that the apoptosis executed at MBT is a “fail-safe” mechanism of early development to save the embryo from accidental damages that take place during cleavage.

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Chk2/Cds1 protein kinase blocks apoptosis during early development of Xenopus laevis

Cited by 11 publications

References 44 publications

Apoptosis in amphibian development

Apoptosis in amphibian development

Features of programmed cell death in intact Xenopus oocytes and early embryos revealed by near-infrared fluorescence and real-time monitoring

Gene Expression in Pre-MBT Embryos and Activation of Maternally-Inherited Program of Apoptosis to be Executed at around MBT as a Fail-Safe Mechanism in Xenopus Early Embryogenesis

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