The retina: from simple epithelium to complex neuronal network
The lab's long-term goal is to understand the development of simple neuroepithelia into complex neuronal networks. Three pre-requisites have to be fulfilled by cells to transition from a progenitor cell into a neuron that is integrated into a functional network:
Proliferative neuronal progenitors have to leave the cell cycle and differentiate into a neuron.
Once committed to neuronal lineages, neurons have to migrate to their correct location, often far away from their place of birth.
Once positioned correctly, neurons have to polarize and extend an axon and numerous dendrites, followed by the formation of connections with appropriate synaptic targets.
The zebrafish retina is an ideal model to gain insight into these questions due to its embryonic transparency and ease of genetic manipulation. Consisting of five types of neurons and one type of glial cell, the retina bears a fascinating high level of complexity but bears the advantage of being a simpler system than less-accessible regions of the CNS due to the shorter migratory distances and smaller overall number of neurons. In this setting we can follow a single cell from its last cell cycles as a progenitor to its birth as a neuron and subsequently even during migration to its final laminar destination and then observe its polarization. Importantly, our investigations will be done in intact tissue and events will be observed and/or manipulated while they occur. As the zebrafish is easy to manipulate genetically as well as pharmacologically more feasible attempts can be made to probe the molecular mechanisms and kinetics of cell cycle, migratory and polarization events. Another advantage of the system is that experiments are relatively easy to perform and therefore big datasets can be acquired that allow strict quantitative analysis of the observed phenomena.
3D reconstruction of a 48hpf retina expressing Ath5-GFP. Ath5 labels Retinal Ganglion cells and thereby the optic nerve that leave the retina towards the optic tectum.
24hpf retina stained against PCNA (as a read out for cell cycle phase of nuclei) phosphorylated Myosin and DAPI.
Future goals
A quantitative analysis of forces and mechanics during Interkinetic Nuclear Migration in a 3D in vivo environment
Dissecting cell cycle events and their links to cytoskeletal dynamics in retinal progenitor cells
Studies of kinetics and mechanics of somal translocation and free migration modes in the retina
The role of intra- and extracellular cues and components during neuronal polarization in vivo
Selected Publications
2012
Wong, Grace K W; Baudet, Marie-Laure; Norden, Caren; Leung, Louis; Harris, William A
Slit1b-robo3 signaling and N-cadherin regulate apical process retraction in developing retinal ganglion cells.
