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. 2016 Feb 15;524(3):518-34.
doi: 10.1002/cne.23806. Epub 2015 Jul 1.

Altered proliferative ability of neuronal progenitors in PlexinA1 mutant mice

William D Andrews  1 , Kathryn Davidson  2 , Nobuaki Tamamaki  3 , Christiana Ruhrberg  2 , John G Parnavelas  1
Affiliations

Altered proliferative ability of neuronal progenitors in PlexinA1 mutant mice

William D Andrews et al. J Comp Neurol. .

Abstract

Cortical interneurons are generated predominantly in the medial ganglionic eminence (MGE) and migrate through the ventral and dorsal telencephalon before taking their final positions within the developing cortical plate. Previously we demonstrated that interneurons from Robo1 knockout (Robo1(-/-)) mice contain reduced levels of neuropilin 1 (Nrp1) and PlexinA1 receptors, rendering them less responsive to the chemorepulsive actions of semaphorin ligands expressed in the striatum and affecting their course of migration (Hernandez-Miranda et al. [2011] J. Neurosci. 31:6174-6187). Earlier studies have highlighted the importance of Nrp1 and Nrp2 in interneuron migration, and here we assess the role of PlexinA1 in this process. We observed significantly fewer cells expressing the interneuron markers Gad67 and Lhx6 in the cortex of PlexinA1(-/-) mice compared with wild-type littermates at E14.5 and E18.5. Although the level of apoptosis was similar in the mutant and control forebrain, proliferation was significantly reduced in the former. Furthermore, progenitor cells in the MGE of PlexinA1(-/-) mice appeared to be poorly anchored to the ventricular surface and showed reduced adhesive properties, which may account for the observed reduction in proliferation. Together our data uncover a novel role for PlexinA1 in forebrain development.

Keywords: Plexin; forebrain; interneurons; neuronal migration; proliferation.

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Figures

Figure 1
Figure 1
Expression patterns of PlexinA1 and Lhx6 in wild‐type mouse brain. A–F: In situ hybridization on coronal sections at E13.5 (A,D), E15.5 (B,E), and E18.5 (C,F) for PlexinA1 (A–C) and the interneuron marker Lhx6 (D–F). Overlapping patterns of expression were observed between PlexinA1 and Lhx6 at all ages. G–H3: Coronal section through the brain of a E14.5 GAD67‐GFP mouse, processed for immunohistochemistry with PlexinA1 antibody (red), showed the presence of the receptor within interneurons in the MGE, LGE, MZ, and IZ in the cortex (arrows H1–H3). CP, cortical plate; SP, subplate; Cx, cerebral cortex; IZ, intermediate zone; LV, lateral ventricle; MGE, medial ganglionic eminence; Str, striatum; SVZ, subventricular zone; Th, thalamus. Scale bars = 200 µm in A (applies to A–F); 200 µm in G; 30 µm in H.
Figure 2
Figure 2
Deletion of PlexinA1 receptor leads to a decreased number of GABAergic interneurons in the cerebral cortex. A–H: Photomicrographs of in situ hybridization for Lhx6 (A–D) and Gad67 (E–H) on coronal sections through the cortex of PlexinA1+/+ (A,C,E,G) and PlexinA1−/− (B,D,F,H) mice at E14.5 (A,B,E,F) and E18.5 (C,D,G,H). I–L: Analysis of the number and distribution of Lhx6‐labeled cells at E14.5 (I) and E18.5 (J) and Gad67 cells at E14.5 (K) and E18.5 (L) in all layers of the cortex of PlexinA1+/+ and PlexinA1−/− mice. Counts were made in the middle region along the rostrocaudal extent of the cortex. Error bars indicate SEM (*P < 0.01, **P < 0.001, ***P < 0.0001). CP, cortical plate; IZ, intermediate zone; MZ, marginal zone; SP, subplate; SVZ, subventricular zone; VZ, ventricular zone. Scale bar = 150 µm.
Figure 3
Figure 3
Reduced number of FOXP2+ cells in the developing striatum of PlexinA1−/− mice. Coronal brain sections from PlexinA1+/+ (A,C) and PlexinA1−/− (B,D) mice at E14.5 were immunostained for FOXP2 (A,B) or processed for in situ hybridization for ER81 (C,D). Quantification of FOXP2+ cells in the striatum of PlexinA1−/− animals showed reduced numbers of labeled cells compared with PlexinA1+/+ littermates at E14.5 (E) and E18.5 (F). Error bars indicate SEM (***P < 0.0005). Str, striatum. Scale bars = 100 µm in A (applies to A,B); 150 µm in C (applies to C,D).
Figure 4
Figure 4
Reduced proliferation in PlexinA1−/− mice. Coronal brain sections from PlexinA1+/+ (A,E,H,J,L) and PlexinA1−/− (B,F,I,K,M) mice at E14.5 were immunostained for PH‐3 (A,B,E,F) and BrdU (H–M). Quantification of PH‐3+ (C,D,G) and BrdU+ (N) cells in the proliferative zones of PlexinA1−/− animals showed reduced numbers compared with PlexinA1+/+ littermates. Error bars indicate SEM (*P < 0.01, **P < 0.001, ***P < 0.0001). Cx, cortex; CGE, caudal ganglionic eminence; MGE, medial ganglionic eminence; LGE, lateral ganglionic eminence. Scale bars = 50 µm in A (applies to A,B); 150 µm in E (applies to E,F); 150 µm in H (applies to H,I); 50 µm in J (applies to J,K); 150 µm in L (applies to L,M).
Figure 5
Figure 5
Reduced number of pyramidal neurons in the cortex of PlexinA1−/− mice. Coronal brain sections from PlexinA1+/+ (A,C,E,G) and PlexinA1−/− (B,D,F,H) mice at E14.5 (A–D) and E18.5 (E–H) were immunostained for Pax6 (A,B), Ctip2 (E,F), and Cux1 (G,H) or processed for in situ hybridization for Er81 (C,D). I: Quantification of Ctip2 and Cux1+ cells in the cortex of PlexinA1−/− animals showed reduced numbers compared with PlexinA1+/+ littermates. Error bars indicate SEM (**P < 0.001). Cx, cortex. Scale bars = 200 µm in A (applies to A,B); 200 µm in C (applies to C,D); 100 µm in E (applies to E,F); 100 µm in G (applies to G,H).
Figure 6
Figure 6
Reduced attachment and altered morphology of progenitor cells in the MGE of PlexinA1−/− mice. Coronal brain sections from PlexinA1+/+ (A) and PlexinA1−/− (B) mice at E14.5 were immunostained for the progenitor cell marker Nestin (A‐B). (A,B) Fewer Nestin‐positive cells appear to be attached to the ventricular wall and positioned perpendicular to the ventricular surface in PlexinA1−/− mice. (C) Quantification of the orientation of the basal process of labelled cells in the VZ/SVZ in PlexinA1−/− mice. (D,E) Mouse embryos electroporated in utero at E12.5 with control‐(GFP)siRNA (D) or PlexinA1‐(GFP)siRNA (E) into the MGE and harvested at E14.5. Fewer cells appear to be attached to the ventricular surface following PlexinA1 knockdown (black arrowheads) compared to control (white arrowheads), quantified in F. (G) Quantification of adhesion assay, showing fewer E12.5 dissociated MGE cells from PlexinA1−/− mice attached to coated coverslips compared to control littermates. Scale bars in A‐B, 20 μm; and D‐E, 50 μm. (*P < 0.01). Error bars indicate SEM. Abbreviation LV, lateral ventricle; MGE, medial ganglionic eminence; VZ, ventricular zone.
Figure 7
Figure 7
Expression patterns of semaphorins and VEGFR2 in wild‐type mouse brain. A–D: In situ hybridization of parasagittal sections at E14.5 for Sema6D (A) VEGFR2 (B), Sema3A (C), and the interneuron marker Lhx6 (D). Images were downloaded from the GenePaint server. E,F: Sema3A‐AP was added to coronal brain sections from PlexinA1+/+ (E) and PlexinA1−/− (F) mice at E14.5. Similar levels of Sema3A‐AP binding were observed in both sets of animals. Scale bars = 300 µm in A (applies to A–D); 200 µm in E (applies to E,F).
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References

    1. Alifragis P, Liapi A, Parnavelas JG. 2004. Lhx6 regulates the migration of cortical interneurons from the ventral telencephalon but does not specify their GABA phenotype. J Neurosci 24:5643–5648. - PMC - PubMed
    1. Andrews W, Barber M, Hernadez‐Miranda LR, Xian J, Rakic S, Sundaresan V, Rabbitts TH, Pannell R, Rabbitts P, Thompson H, Erskine L, Murakami F, Parnavelas JG. 2008. The role of Slit–Robo signaling in the generation, migration and morphological differentiation of cortical interneurons. Dev Biol 313:648–658. - PubMed
    1. Andrews WD, Zito A, Memi F, Jones G, Tamamaki N, Parnavelas JG. 2013. Limk2 mediates semaphorin signaling in cortical interneurons migrating through the subpallium. Biology Open 2:277–282. - PMC - PubMed
    1. Arellano JI, Guadiana SM, Breunig JJ, Rakic P, Sarkisian MR. 2012. Development and distribution of neuronal cilia in mouse neocortex. J Comp Neurol 520:848–873. - PMC - PubMed
    1. Arlotta P, Molyneaux BJ, Chen J, Inoue J, Kominami R, Macklis JD. 2005. Neuronal subtype‐specific genes that control corticospinal motor neuron development in vivo. Neuron 45:207–221. - PubMed

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