7/n The first signaling phase induces expression of the roof plate transcription factor LMX1A, which then initiates a slow positive feedback loop that involves both BMP and WNT signaling. This loop triggers the second phase of BMP signaling by inducing endogenous BMP production.

5/n We found that in the colonies, there is a BMP signaling gradient from the periphery to the center, but strikingly – this gradient appears rapidly, then disappears, then appears again. Similar dynamics are likely to take place in the embryo.

4/n Our system uses stencils to transiently constrain colony geometry, which makes the system reproducible and quantitative, and also allows colony growth and neural crest migration. The approach is described in our STAR Protocols paper.

3/n To study this, we developed a 2D organoid system in which the dorsal neural tube pattern self-organizes into concentric domains in response to BMP, with neural crest at the periphery, followed by roof plate and neural progenitor domains towards the center.

2/n Self-organized pattern formation depends on the formation of localized sources of morphogen production, but how are these sources established? We found that in neural tube cells, an endogenous BMP source forms in response to an earlier precisely timed pulse of BMP signaling.

🚨We are recruiting!🚨 We are currently looking for postdoctoral researchers to join our group to investigate events during early development of the neural tube. Sound interesting? See more: ista.ac.at/en/job/postdoc-re…

5/7 The model explains the relationship between floor plate size and Shh amplitude in conditions where Shh production is altered.

4/7 Subsequently, the floor plate becomes insensitive to Shh and expands by growth. This in turn leads to an increasing Shh amplitude as the tissue grows.

2/7 Using a computational model we show that the floor plate can form by either rapid or ongoing specification in response to Shh, but only the former is consistent with experimental data.

Our paper “Dynamics of morphogen source formation in a growing tissue” with first authors R. Ho and K. Kishi is published in @PLOSCompBiol 🎉 We show that the floor plate of the vertebrate neural tube forms in two phases: rapid specification followed by growth. 🧵1/7

Our final latest addition to the lab at @ISTAustria is our fantastic new Postdoc @jindriskalf ! She will expand on our work in understanding #neuraltube pattern formation our 2D organoid system #signalling #morphogens. We are all excited to have you here!