Wnt signaling; layer II pyramidal neurons; development; in utero electroporation; video time-lapse microscopy; cell migration
Sheybani Laurent, Birot Gwenaël, Contestabile Alessandro, Seeck Margitta, Kiss Jozsef Zoltan, Schaller Karl, Michel Christoph M., Quairiaux Charles (2018), Electrophysiological Evidence for the Development of a Self-Sustained Large-Scale Epileptic Network in the Kainate Mouse Model of Temporal Lobe Epilepsy, in The Journal of Neuroscience
, 38(15), 3776-3791.
Petrenko Volodymyr, van de Looij Yohan, Mihhailova Jevgenia, Salmon Patrick, Hüppi Petra S, Sizonenko Stéphane V, Kiss Jozsef Z (2018), Multimodal MRI Imaging of Apoptosis-Triggered Microstructural Alterations in the Postnatal Cerebral Cortex, in Cerebral Cortex
, 28(3), 949-962.
Bocchi Riccardo, Egervari Kristof, Carol-Perdiguer Laura, Viale Beatrice, Quairiaux Charles, De Roo Mathias, Boitard Michael, Oskouie Suzanne, Salmon Patrick, Kiss Jozsef Z. (2017), Perturbed Wnt signaling leads to neuronal migration delay, altered interhemispheric connections and impaired social behavior, in Nature Communications
, 8(1), 1158-1158.
Kanemitsu Michiko, Tsupykov Oleg, Potter Gaël, Boitard Michael, Salmon Patrick, Zgraggen Eloisa, Gascon Eduardo, Skibo Galina, Dayer Alexandre G., Kiss Jozsef Z. (2017), EMMPRIN overexpression in SVZ neural progenitor cells increases their migration towards ischemic cortex, in Experimental Neurology
, 297, 14-24.
Tsupykov Oleg, Kanemitsu Michiko, Smozhanik Ekaterina, Skibo Galina, Dayer Alexandre G., Kiss Jozsef Z. (2016), Relationship of Grafted FGF-2-Overexpressing Neural Stem/Progenitor Cells with the Vasculature in the Cerebral Cortex, in Cell Transplantation
, 25(7), 1359-1369.
Egervari Kristof, Potter Gael, Guzman-Hernandez Maria Luisa, Salmon Patrick, Soto-Ribeiro Martinho, Kastberger Birgit, Balla Tamas, Wehrle-Haller Bernhard, Kiss Jozsef Zoltan (2016), Astrocytes spatially restrict VEGF signaling by polarized secretion and incorporation of VEGF into the actively assembling extracellular matrixSecretion and Function of VEGF in Astrocytes, in Glia
, 64(3), 440-456.
The proper development of cortical circuits requires highly orchestrated cell migratory events to establish specific laminar position, orientation and connectivity of neurons. Migration errors can lead to neurodevelopmental disorders including heterotopia, lissencephaly and focal cortical dysgenesis. Wnt signal transduction pathways have been implicated in psychiatric and neurological pathologies that have been associated with neuronal migration disorders. While it has been speculated that Wnt signaling might control neuronal migration, its direct role remained to be established. During the last funding period we have demonstrated that dynamically regulated activity states of canonical Wnt/ß-catenin signaling during specific migratory phases are crucial for proper polarization and migration of late generated pyramidal neurons (Boitard et al., 2014, under revision). But, how specific Wnt signaling levels are established and the mechanisms by which canonical Wnt signaling regulates migratory events remain unknown. In preliminary experiments we found that Wnt non-canonical signaling just as the ß-catenin-dependent canonical signaling transduction is active in radially migrating cells. Moreover, we show that the best characterized non-canonical ligand, Wnt5a is expressed in pyramidal precursor cells. Our preliminary experiments also suggest that there might be a crosstalk between autocrine Wnt5a/non-canonical signaling and the canonical pathway.Hypothesis: Wnt canonical and non-canonical signaling pathways cooperate in migrating pyramidal precursors to regulate cell polarization, migration and early differentiation events. Aims: We will test this hypothesis focusing on rat layer II pyramidal cells at different developmental stages including: 1) the multipolar to bipolar transition in the upper subventricular zone; 2) transitions at the level cortical plate and radial glia guided locomotion; and 3) early dendritic development including dendritic branching and spine formation. In order to test specific hypotheses concerning the role of Wnt signaling pathways in these events, we propose to electroporate doxycycline inducible constructs in utero to carry out loss-of-function or gain-of-function experiments with delayed activation. We will investigate the effects of manipulating Wnt signaling on polarization, migration and early differentiation of pyramidal cells using confocal microscopy. In order to monitor in real time the migration of neurons, video time-lapse imaging will be performed on slice preparations. Intracellular iontophoretic injection of Lucifer Yellow will be performed to achieve complete filling of apical and basal dendrites with dendritic spines. Reconstruction of three-dimensional dendritic structures will be carried out on a computer-based Neurolucida system.Significance: The work proposed here may uncover how the coordinated activity of canonical and non-canonical signaling cascades control key migratory and differentiation events of pyramidal cells. Our results hold promise for understanding the mechanisms by which deregulation of Wnt signaling pathways could impact on postmitotic neurons thereby potentially underlying neurodevelopmental disorders.