Study of gliogenic progenitors within the hindbrain
1Carla Belmonte-Mateos and 1Cristina Pujades1Department of Experimental and Health Sciences, Universitat Pompeu Fabra
The hindbrain is the most posterior embryonic brain vesicle of the Central Nervous System (CNS) and one of the most highly conserved structures in vertebrates. Its derivatives control numerous physiological processes (Aldinger et al., 2009). During embryonic development, it is transiently subdivided in seven bulges called rhombomeres, whose molecular identity prefigure cell specification.
Within the hindbrain, neurogenesis is initiated by proneural genes, regionalized over time, and restricted in space (Glez-Quevedo et al 2010). Little is known, however, about how gliogenesis takes place and how these different capacities are allocated.
Recent studies in zebrafish show sox9 is expressed in the center of the rhombomeres, an area devoid of neurogenesis (Esain et al., 2010). Nevertheless, sox9 appears to play a key role in activating glial specification in mice spinal cord (Stolt et al., 2003) but not in initiating gliogenesis in cerebellum (Vong et al., 2015). These observations suggest gliogenesis may be context dependent rather than a general mechanism in the central nervous system.
We aimed to understand how glial progenitors are specified and regulated within the embryonic hindbrain. We analyzed the spatiotemporal expression of sox9 genes within the hindbrain and showed that their onset of expression is preceded by the onset of neurogenesis. Moreover, our preliminary results show that neurogenic and gliogenic domains are spatially and temporally segregated during cell specification, suggesting that neurons and glial cells originate from different progenitor pools. We are also investigating the role of the Notch pathway during gliogenesis to understand how both populations are established. Coupling these studies with glial cell lineage tracing we hope to determine how gliogenic progenitors behave over time and to shed light on the poorly explored gliogenic process during development.