Talk by Stefan Semrau (MIT): 'Stem cell differentiation as a symmetry breaking process'



11.30 - 12.30


Huygens, Niels Bohrweg 2/room 207, Leiden


You are cordially invited to attend the talk of Stefan Semrau from MIT on Monday 25 November from 11:30-12.30, room  HL207.

Stefan  ( is one of the applicants to Thomas Schmidt's new faculty positions, and you might be interested to learn about our potential new colleagues.


Stem cell differentiation as a symmetry breaking process   

Symmetry breaking is a prevalent principle in biology and of great importance for a diverse range of phenomena including membrane heterogeneity, directional cell motility and embryonic development. Especially in embryonic development it is obvious that increasing levels of broken symmetry correlate with increasing complexity and functional specialization. How  this specialization is executed in a robust and timely manner is a fundamental question in developmental biology.   

In this talk I will present my recent work on symmetry breaking during the differentiation of mouse embryonic stem cells. I will describe a  minimal differentiation protocol, which allows me to study differentiation in unprecedented detail. After adding a single chemical cue the stem cells develop from a homogeneous starting population to a mixture of different cell types. Using state-­‐of-­‐ the-­‐art techniques to measure the state (i.e. gene expression) of single cells I was able to show that two mutually exclusive subpopulations coexist. Most importantly these experiments also showed that symmetry breaking  -­ the decision to develop into a particular cell type -­ and the actual change of the cell state -­‐  commitment to the chosen cell  type‐  are separate events.   

By targeted and precisely timed genetic perturbations I am currently identifying the most relevant molecular players influencing the cell type decision and execution of commitment. In particular I would like to understand the mechanisms by which the fluctuations of certain genes are amplified leading to a robust cell type decision.   

The combination of genetic perturbations and techniques to read  out the state of single cells  will  give  us  a comprehensive picture  of the differentiation process. Insights from these studies will also likely improve the production of clinically relevant cell types from embryonic stem cells.