Dr. Patrick Cormier
Translational control is the main driver of gene expression in early stages of development, more specifically during the egg-to-embryo transition. Early embryo mitotic divisions offer the opportunity to discover regulatory mechanisms that dictate mRNA translational regulation in relation with cell cycle. Echinoderms are sister to the chordates; in sea urchins maternal mRNAs deposited in the egg drive the first mitotic cell cycles induced by fertilization independently of mRNA transcription and ribosome biogenesis. Global and specific mRNA translations are highly controlled following fertilization and are necessary for the complete and correct progress of the mitotic events induced by the fertilization of the egg . Our group recently optimized in sea urchin high-throughput processing of polysome gradients, for the simultaneous screening of multiple biological conditions and large-scale preparation of samples for next-generation sequencing. Using this approach we have obtained the first complete picture of the complex translation dynamics following fertilization in sea urchin. Among the over-represented transcripts that were significantly recruited onto active polysomes after fertilization (2514 transcripts, 18% of the maternal set), strikingly 13 and 5 transcripts encoded respectively for cell cycle and translational actors. We are currently analysing the role and the translational regulation of these actors in the context of the control of the mitotic division following fertilization and during early embryogenesis in sea urchin.
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