ZFIN Image: Maerker et al., 2021, Fig. 8

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Figure Caption

Fig. 8 Two modes of Bicc1-dependent post-transcriptional regulation of <italic>gdf3</italic> and <italic>dand5</italic> in flow sensor cells at the <italic>Xenopus</italic> left-right organizer.

In the early neurula pre-flow stages, Bicc1 has two functions. Bicc1 assures gdf3 mRNA translation and thereby indirectly ensures nodal1 transcription by Gdf3 signaling. Simultaneously Bicc1 mediates dand5 mRNA stability via the medial (m) sub-region of the Bicc1RE. Thus, Dand5 protein levels are sustained on both sides, keeping Nodal in tight repression. Leftward flow activates the Pkd2 channel in left flow sensor cells, resulting in an asymmetric calcium signal. In post-flow stages, a calcium-dependent mechanism activates/modifies Bicc1 to become a repressor of dand5 translation, which is relayed by the distal (d) sub-region of the Bicc1RE. Subsequently, dand5 mRNA gets degraded in a Dicer1 (miR) dependent manner. Attenuated Dand5 expression lifts repression of Nodal and defines leftness by induction of the LPM Nodal signaling cascade. For details, see text.

Acknowledgments

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