Cluster of Excellence –
University of Freiburg

Optogenetic control of dopaminergic neurogenesis

Prof. Dr. Wolfgang Driever (Institute of Biology I, University of Freiburg)

 

The precise spatial and temporal control of stem cell proliferation and differentiation in the neural stem cell (NSC) niche is not well understood, but this knowledge would be instrumental for future regenerative approaches to neurodegenerative disease and CNS injury. Dopaminergic neurons, which die in Parkinson's disease, are one population of neurons for which knowledge on their neurogenesis bears great biomedical potential.  While it is still impossible to locally control neurogenesis in the intact brain, we develop zebrafish as an experimental model to discover mechanisms of dopaminergic neurogenesis, but also to develop tools for locally and temporally controlled gene expression to initiate regeneration or repair of brain tissue.

Towards these goals, we have created detailed signaling maps that reveal signaling activities of major developmental signaling pathways in the developing brain (see Figure). We integrate this knowledge with the local activities of Delta/Notch signaling, which controls neural stem cell maintenance and precursor differentiation. We develop tools to locally control these developmental signals, as well as the expression of bHLH transcription factors involved in neurogenesis, and of transcription factors specifically driving dopaminergic differentiation.  Local and temporally controlled expression will be achieved using blue light driven gene expression systems including the EL222 system and its modifications (Motta-Mena et al., Nat. Chem. Biol. 2014). Potential effects on neurogenesis and generation of new neurons can be visualized using our dopaminergic neuron specific fluorescent marker lines.

A map of signaling activities in the developing zebrafish brain.
The activities of the developmental signals BMP, SHH and WNT together with the neurogenesis signal of activated Notch are visualized using transgenic reporter lines expressing fluorescent proteins in response to specific signals. Confocal microscopy of three day old larval zebrafish brains and image registration using our Vibe-Z system (Ronneberger et al., Nat. Meth. 2012) was used to generate this signaling map. Shown is a z-projection of a confocal stack, anterior is at left.