PlexinD1 and Sema3E determine laminar positioning of heterotopically projecting callosal neurons

© 2019 The Authors.
The corpus callosum is the largest bundle of commissural fibres that transfer information between the two cerebral hemispheres. Callosal projection neurons (CPNs) are a diverse population of pyramidal neurons within the neocortex that mainly interconnect homotopic regions of the opposite cortices. Nevertheless, some CPNs are involved in heterotopic projections between distinct cortical areas or to subcortical regions such as the striatum. In this study, we showed that the axon guidance receptor PlexinD1 is expressed by a large proportion of heterotopically projecting CPNs in layer 5A of the primary somatosensory (S1) and motor (M1) areas. Retrograde tracing of M1 CPNs projecting to the contralateral striatum revealed the presence of ectopic neurons aberrantly located in layers 2/3 of Plxnd1 and Sema3e mutant cortices. These results showed that Sema3E/PlexinD1 signalling controls the laminar distribution of heterotopically projecting CPNs.
This work was supported by the Centre National de la Recherche Scientifique (CNRS), France; Aix Marseille Université, France; Agence Nationale de la Recherche, ANR-12-BSV4-0012-01, France to F.M.; Fondation pour la Recherche Medicale, Equipe FRM DEQ20150331728, France to F.M., Institut Universitaire de France, France, to S.C.. T.V. is a recipient of doctoral fellowships from the Integrative and Clinical Neuroscience PhD Program and from the Fondation pour la Recherche Medicale, France.