The Eph/ephrin family have been shown to act as cues that guide interneurons for the duration of their tangential migration (Zimmer et al., 2008; Rudolph et al., 2010; Zimmer et al., 2011). We performed in situ hybridization on coronal sections to examine the expression patterns of EphB1 and ephrin-B3 in the basal telencephalon at E14. EphB1 riboprobes revealed a sturdy signal within the Str and in the VZ in the ganglionic eminences and the POA. These are all regions which might be avoided by migrating cortical interneurons. In contrast, at these developmental stages the ligand ephrin-B3 is expressed inside the POA and in the IMZ, ventral of your Str, an region which is a part of the SMS of cortical interneurons. The complementary expression patterns of EphB1 and ephrin-B3, illustrated by the pseudocolor overlay (Figure 1I), suggests that EphB1 may act as a repellent cue for cortical interneurons bearing the ephrin-B3 ligand. To test this hypothesis we performed the experiments described within the following sections.POA-DERIVED NEURONS INVADE THE STRIATUM Immediately after BLOCKING EPHRIN-B LIGANDSAt the peak of interneuron migration (E14 within the mouse), cortical interneurons born in distinct regions of the basal telencephalon stick to separate routes when they migrate towards the cortex: an outer SMS and an inner or deep migratory stream (DMS; Corbin and Butt, 2011; Zimmer et al., 2011). These two migratoryPreviously we have shown that MGE- and POA-derived cortical interneurons migrate in spatially segregated corridors, in the deep and also the superficial stream, respectively (Zimmer et al.1403850-00-9 Chemscene , 2011).Frontiers in Cellular Neurosciencefrontiersin.orgJuly 2014 | Volume 8 | Post 185 |Rudolph et al.Guiding migrating cortical and striatal neuronsFIGURE two | Invasion of the striatum following blocking of endogenous ephrin-Bs in organotypic slice cultures. The tangential migration of CellTracker C2925-labeled neurons on the superficial migratory stream in organotypic slices was investigated after blocking ephrin-B function. (A) Labeled SMS-cells in E14 slices following 1 DIV migrate primarily within the piriform cortex, avoiding the striatum in manage circumstances. (B) Just after blocking endogenous ephrin-B ligands with EphB1-Fc, labeled cells on the SMS invade the striatal anlage. (C) Quantitative analysis in the distribution of CellTracker C2925 labeled neurons at E14 plus 1 DIV beneath control conditions and afterapplication of five /ml EphB1-Fc. (D) Schematic view of a coronal brain slice as utilised for the grafting experiments, illustrating the analyzed area which was horizontally divided into 10 equal segments, with segment 1? representing the proliferating zones, segments 5? the striatum and segments eight?0 the piriform cortex.2908-71-6 custom synthesis Lateral is appropriate and medial is left.PMID:24140575 GP Globus pallidus; LGE, , lateral ganglionic eminence; MGE, medial ganglionic eminence; SMS, superficial migratory stream; Str, Striatum. n = number of analyzed slices. Error bars indicate SEM. One-way ANOVA *p 0.05, **p 0.01, ***p 0.001. Scale bars: 500 .Ephrin-B3, expressed in POA-derived interneurons traversing the superficial route, acts as a repellent signal for deeply migrating interneurons born within the MGE, which can be mediated by EphA4 forward signaling. In contrast, EphA4 induces repulsive ephrin-B3 reverse signaling in interneurons generated within the POA, restricting this population towards the superficial path. Considering that most cells inside the superficial stream don’t enter the Str, exactly where EphB1 is expressed, and considering that the majority of these neurons bear the ephrin-B3 li.
