Biosciences Research Seminar - Pluripotency factors in zebrafish embryo

Part of the Biosciences lunchtime research seminar series

A Biosciences seminar
Date1 July 2021
Time12:30 to 13:30
PlaceEvent held via Microsoft Teams

Speaker: Dr Daria Onychtchouk, Developmental Biology Department, Biologie I, University of Freiburg. Host: Dr Tetsu Kudoh


Abstract

Awakening of zygotic transcription in zebrafish embryos relies on maternal pioneer transcription factors Pou5f3, Sox19b and Nanog, the homologs of mammalian pluripotency factors. The interplay of global and specific functions of these proteins remains poorly understood. We analysed time-resolved transcription, chromatin state and embryonic phenotypes of zebrafish embryos lacking Pou5f3, Sox19b or both. We show that the bulk transcriptional onset does not require Sox19b and Pou5f3, but is sensitive to their balance. Pou5f3 docks H3K27ac on the enhancers of genes involved in gastrulation and ventral fate specification. The genes regulating mesendodermal and dorsal fates are primed for activation independently on Pou5f3 and Sox19b. Strikingly, the simultaneous loss of both factors leads to premature expression of differentiation genes. Our results uncover how the activities of maternal Pou5f3 and Sox19b add up or antagonize to determine the early gene expression repertoire.

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