Student in Spotlight – Petra Tauscher

For the month of November 2016

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Petra Tauscher is a PhD student at the Institute of Biotechnology, Developmental Biology Program with Group Leader Dr. Osamu Shimmi. She is studying the post-transcriptional regulation of TGF-beta type signaling in Drosophila development, and has recently published an article on this topic. Congratulations Petra!

Developmental patterning and intrinsic properties of BMP ligands

Research Digest:

A fascinating area of research in biology is to understand how animals transform from a single-cell zygote to a fully-grown adult with sophisticated organ systems. Previous studies have shown that the genetic mechanisms of a huge variety of animal species during development is conserved, i.e. a similar group of genes carry out a conserved set of molecular functions. How is it possible that animals look so different, despite using the same mechanisms?

Because the developmental processes are conserved, it allows researchers to conduct studies in model organisms. For instance, invertebrates like fruit flies, as well as vertebrates use the same set of molecules for dorsal/ventral patterning (DV) during embryogenesis which ultimately determines the back/belly in adult form. The Bone Morphogenetic Protein (BMP) signaling pathway is one such conserved signaling that plays a crucial role during this process. It is also important for the posterior cross-vein (PCV) formation during pupal stage, which develops into the wings in flies. So how does the BMP signaling pathway result in DV patterning in one, and PCV in another context of development?

Previous studies suggest that changes in gene regulation affect BMP signaling in a spatiotemporal manner. Petra’s experiments [1] add a new aspect to this idea. She compared the protein sequences of BMP-type ligands from various species and found that the BMP-type ligands contain a highly conserved N-glycosylation motif. However, Screw, a BMP-type ligand in fly, carries an additional unique N-glycosylation motif that is not present in other BMP-type ligands. While Screw is critical and exclusively found in the context of dorsal/ventral patterning, Glass bottom boat, a paralog of Screw plays a role during PCV formation in fly. Petra et al. found that Screw, if expressed artificially in the wing can replace the function of Glass Bottom Boat during PCV formation, but vice-versa is not true. Furthermore, BMP-type ligands lacking N-glycosylation motifs were more efficient in the context of PCV formation, whereas lack of N-glycosylation in the Screw ligand led to a reduced viability. This suggests that N-glycosylations provide an advantage for DV patterning, i.e. during early stages of embryogenesis but are detrimental during PCV formation. Hence, N-glycosylation motifs affect BMP function in a context dependent manner.

Petra thereby concludes that apart from the spatial and temporal changes in gene expression, post-translational modifications may be one way how evolutionarily conserved molecules and signaling pathways adapt to different developmental processes.

  1. Tauscher PM, Gui J, Shimmi O. Adaptive protein divergence of BMP ligands takes place under developmental and evolutionary constraints. Development. 2016 Oct 15;143(20):3742-3750.