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Survivin mRNA is down-regulated during early Xenopus laevis embryogenesis
Cary R Murphy1, Jaime L Sabel, Anthony D Sandler
1Department of Pediatrics, University of Iowa, Iowa City, Iowa 52242, USA.
Abstract:
One of the hallmarks of early development is the rapid proliferation of cells immediately after fertilization. Many of the rules that govern cell division in normal somatic cells, such as contact inhibition and apoptosis, seem temporarily suspended in the early embryo. A similar suspension of mechanisms normally regulating cell division occurs in the development of cancer. Survivin, an inhibitor of apoptosis and a positive regulator of progression through the cell cycle, localizes to the mitotic spindle and interacts with several proapoptotic caspases. Survivin protein expression has been studied during the development of the salivary gland in mouse. However, the regulation of survivin during the critical transitions defining oocyte maturation and the early restriction of developmental potential are not easily examined in the mouse. We therefore studied survivin mRNA expression during oogenesis and early embryogenesis in Xenopus laevis. We found that survivin mRNA is present in the earliest stages of Xenopus oocytes and that it accumulates during oogenesis. Progesterone-induced maturation of Xenopus oocytes leads to polyadenylation of the survivin transcript. Survivin mRNA is also present in early Xenopus embryos. After the onset of zygotic transcription, however, the amount of survivin mRNA declines rapidly to undetectable levels. This decrease in survivin mRNA correlates temporally with both the slowing of the cell cycle and the onset of endogenous embryonic apoptosis. With the exception of the ovary, survivin mRNA was undetectable in all adult Xenopus tissues examined.
Insights
Survivin mRNA is abundant in early Xenopus development, accumulating during oogenesis and early embryogenesis. Its levels rapidly decline after zygotic transcription begins, correlating with cell cycle slowing and apoptosis onset.
Area of Science:
- Developmental Biology
- Cell Biology
- Molecular Biology
Background:
- Rapid cell proliferation is characteristic of early embryonic development, with typical cell division regulators like apoptosis temporarily suspended.
- Survivin, an apoptosis inhibitor and cell cycle regulator, is crucial in cell division and has been studied in mouse salivary gland development.
- Examining survivin regulation during oocyte maturation and early developmental potential restriction is challenging in mice.
Purpose of the Study:
- To investigate survivin mRNA expression during oogenesis and early embryogenesis in Xenopus laevis.
- To understand the temporal regulation of survivin during critical developmental transitions.
- To correlate survivin expression with cell cycle progression and apoptosis in early embryos.
Main Methods:
- Studied survivin mRNA expression in Xenopus laevis oocytes and embryos using molecular techniques.
- Analyzed survivin transcript polyadenylation during progesterone-induced oocyte maturation.
- Quantified survivin mRNA levels at different embryonic stages, including post-zygotic transcription onset.
Main Results:
- Survivin mRNA is present in early Xenopus oocytes and accumulates throughout oogenesis.
- Progesterone treatment induces polyadenylation of the survivin transcript in maturing oocytes.
- Survivin mRNA is detected in early embryos but rapidly decreases to undetectable levels after zygotic transcription begins.
- The decline in survivin mRNA correlates with cell cycle slowing and the onset of embryonic apoptosis.
- Survivin mRNA is undetectable in adult Xenopus tissues, except for the ovary.
Conclusions:
- Survivin plays a role in early Xenopus development, with its expression dynamically regulated during oogenesis and embryogenesis.
- The dynamic changes in survivin mRNA levels are linked to key developmental events like cell cycle progression and apoptosis.
- Xenopus laevis serves as a valuable model for studying the regulation of survivin during early development.