CEMO monthly seminar - Alexia Cossard

April 01, 2020


Gerty Cori room (Laennec tower) - Woluwe

CEMO is delighted to announce the seminars of the department that will be given by PhD student and Postdoc.

The seminar is followed by a lunch (kindly provided by the department) in order to allow everybody to interact and promote collaboration between labs.


12:00 - “RhoA GTPase in late Embryonic Apical Neural Stem Cells in the Mammalian Cerebral Cortex” - Alexia Cossard (MACE lab)


Excitatory neurons, the major type of neurons in the cerebral cortex, are produced by Neural Stem Cells (NSCs) located in a region called the ventricular zone (VZ). Initially, NSCs mainly self-renew, resulting in an expansion of their number. They then progressively switch into another type of proliferative cells called radial glia cells or apical NSCs (aNSCs) and start producing basal progenitors and neurons. The maintenance of the balance between proliferation, self-renew, and differentiation is crucial to the formation of a normal cortex. Disruption of the molecular and cellular mechanisms that regulate these processes can lead to severe cortical malformations (neuronal heterotopy, microcephaly...).

The small GTPase RhoA plays key roles in fundamental functions such as regulation of actin cytoskeleton, microtubule movement, and regulation of gene expression. It is highly expressed in the VZ of the developing cerebral cortex and its conditional deletion in early NSCs of the cerebral cortex induces a loss of adherens junctions associated with massive disorganization of the tissue and overproliferation of NSCs. However, nothing is known about its function in the later stage. Since early NSCs mostly self-renew while late aNSCs divide asymmetrically to produce postmitotic cells, we hypothesized that RhoA function might not be the same at different developmental stages.

In this project, we investigate RhoA functions during late neurogenesis utilizing an alternative approach that only affects a subset of cells in a cell-autonomous manner. Using in utero electroporation and molecular techniques, we found that RhoA positively regulates proliferation and controls differentiation into basal progenitors or postmitotic neurons in the cerebral cortex before and therefore independently to the occurrence of tissue disorganization.

12:45 - Q&A session

13:00 - Lunch