BioProject

In the mammalian cerebral cortex, the developmental events governing the allocation of different classes of inhibitory neurons into distinct cortical layers are poorly understood. More...

In the mammalian cerebral cortex, the developmental events governing the allocation of different classes of inhibitory neurons into distinct cortical layers are poorly understood. Here we report that the guidance receptor PlexinA4 is upregulated in serotonin receptor 3a-expressing (HTR3A) cortical interneurons (hINs) as they invade the cortical plate and that it regulates their laminar allocation to superficial cortical layers. We find that the PlexinA4 ligand Semaphorin3A acts as a chemorepulsive factor on hINs migrating into the nascent cortex and demonstrate that Semaphorin3A specifically controls their laminar positioning through PlexinA4. We identify that deep layer interneurons constitute a major source of Semaphorin3A in the developing cortex and demonstrate that cell-type specific genetic deletion of Semaphorin3A in these interneurons specifically affects the laminar allocation of hINs. These data demonstrate that in the neocortex, deep layer interneurons control the laminar allocation of hINs into superficial layers. Overall design: hINs from E14.5, E18.5 and P2 (from controls and Htr3a-KO brains) have been dissociated and FACS-sorted to isolate cells migrating tangentially, invading the cortical plate and settling into the cortex, respectively. Triplicates from 3 different litters were obtained by pooling at least 4 brains. RNA was extracted with Quiagen Rneasy mini kit and quality assessed with Agilent 2100 Bioanalyser. Total RNA was amplified and labeled with Affymetrix small-scale protocol. Biotynilated cDNA was fragmented and hybridized to Mouse Genome 430 2.0 Array (Affymetrix) according to manufacturer's protocol. GeneChips were incubated with biotin-labeled cRNAs probes and stained with streptavidin-phycoerythrin conjugated with antibody amplification using Affymetrix GeneChip Fluidis Station 450. GeneChips were scanned on GC3000 scanner, signal intensities analyzed with Partek Genomic Suite v. 6.6 beta and data normalized using robust multi-array average (RMA). Less...