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Translational control during early development
1Worcester Foundation for Biomedical Research, Shrewsbury, MA 01545, USA.
Abstract:
The regulation of gene expression during early development is controlled predominantly at the translational level. This becomes necessary due to transcriptional arrest during maturation of the oocyte and the rapid early cleavage divisions of the embryo. Consequently, early events involved in pattern formation, germ cell specification, cell fate, and cell division are programmed by maternal messenger ribonucleic acid (RNA). The majority of these transcripts are stored as masked ribonucleoproteins particles during oogenesis but undergo sequence-specific translational activation during oocyte maturation and embryogenesis. Translational regulation occurs in the male germ line and, though not a prominent feature, in the soma as well. Evidence suggests that the assembly of ribonucleoprotein (RNP) particles may be coupled to transcription. Specific translational regulatory sequences are found in the 5' and 3' untranslated regions of maternal mRNA, but the majority occur downstream of the coding region. Most of the known cis-acting sequences and associated proteins are implicated in translational repression. Antisense RNA also has been implicated in specific mRNA translational regulation. Although little is known about message-specific unmasking, in general, one exception is cytoplasmic polyadenylation-mediated translational activation. A widespread phenomenon, it occurs in both vertebrates and invertebrates.
Insights
Gene expression in early development relies on translational control, using maternal messenger RNA (mRNA) stored as ribonucleoprotein (RNP) particles. These RNPs are activated during oocyte maturation and embryogenesis for crucial developmental events.
Area of Science:
- Developmental Biology
- Molecular Biology
- Genetics
Background:
- Gene expression regulation is critical during early development.
- Transcriptional arrest occurs during oocyte maturation and early embryonic divisions.
- Maternal messenger RNA (mRNA) programs early developmental events.
Purpose of the Study:
- To elucidate the mechanisms of translational control in early development.
- To understand the role of maternal mRNA and ribonucleoprotein (RNP) particles.
- To identify regulatory sequences and factors involved in translational activation and repression.
Main Methods:
- Analysis of maternal mRNA storage and translational activation.
- Identification of cis-acting regulatory sequences in mRNA.
- Investigation of proteins associated with translational regulation.
- Study of antisense RNA involvement in translational control.
Main Results:
- Maternal mRNA is stored as masked ribonucleoprotein (RNP) particles.
- Sequence-specific translational activation of maternal mRNA occurs during oocyte maturation and embryogenesis.
- Regulatory sequences are located in untranslated regions and downstream of coding regions.
- Translational repression is mediated by specific cis-acting sequences and proteins.
- Cytoplasmic polyadenylation is a key mechanism for translational activation.
Conclusions:
- Translational regulation is the predominant mechanism controlling gene expression in early development.
- Maternal mRNA stored in RNP particles plays a vital role in programming embryonic development.
- Specific regulatory elements and proteins govern mRNA translation, with cytoplasmic polyadenylation being a widespread activation mechanism.