α2-chimaerin controls neuronal migration and functioning of the cerebral cortex through CRMP-2

Journal name:
Nature Neuroscience
Volume:
15,
Pages:
39–47
Year published:
DOI:
doi:10.1038/nn.2972
Received
Accepted
Published online

Abstract

Disrupted cortical neuronal migration is associated with epileptic seizures and developmental delay. However, the molecular mechanism by which disruptions of early cortical development result in neurological symptoms is poorly understood. Here we report α2-chimaerin as a key regulator of cortical neuronal migration and function. In utero suppression of α2-chimaerin arrested neuronal migration at the multipolar stage, leading to accumulation of ectopic neurons in the subcortical region. Mice with such migration defects showed an imbalance between excitation and inhibition in local cortical circuitry and greater susceptibility to convulsant-induced seizures. We further show that α2-chimaerin regulates bipolar transition and neuronal migration through modulating the activity of CRMP-2, a microtubule-associated protein. These findings establish a new α2-chimaerin-dependent mechanism underlying neuronal migration and proper functioning of the cerebral cortex and provide insights into the pathogenesis of seizure-related neurodevelopmental disorders.

At a glance

Figures

  1. [alpha]2-chimaerin is essential for neuronal migration during neocortex development.
    Figure 1: α2-chimaerin is essential for neuronal migration during neocortex development.

    (a) α2-chimaerin was localized to the intermediate zone and the cortical plate in the developing mouse neocortex. E15 and E17 cortical sections were immunostained with antibodies to α2-chimaerin (green) and Tuj1 (red). CP, cortical plate; IZ, intermediate zone; VZ, ventricular zone. Scale bars, 100 μm. (b) Results of in utero electroporation of E14 mouse embryos with GFP plasmids together with pSUPER vector (pSUPER) or pSUPER-based shRNAs targeting α2-chimaerin (α2-shRNA or α2-shRNA-2). Representative coronal brain sections at E17 were stained with antibodies to GFP (green) and CS-56 (red), a subplate marker, and counterstained with TO-PRO3, a nuclear marker (blue). Scale bar, 100 μm. (c) Morphological defects of migrating neurons in the intermediate zone after depletion of α2-chimaerin. Right subpanels: drawings of representative neurons denoted by asterisks in the left subpanels. Scale bar, 20 μm. (d) Quantification of the distribution of GFP+ neurons. ***P < 0.001; Student's t-test. More than 1,000 GFP+ neurons from three to five brains were analyzed in each group. (e) Quantification of percentage of neurons with uni- or bipolar morphology, no processes or multiple (≥3) minor processes. *P < 0.05, ***P < 0.001 versus pSUPER control; Student's t-test. More than 100 GFP+ neurons from three brains were examined in each group. Error bars, s.e.m.

  2. [alpha]2-chimaerin regulates multipolar-bipolar transition.
    Figure 2: α2-chimaerin regulates multipolar-bipolar transition.

    (a) α2-chimaerin knockdown impairs the transition to a bipolar morphology. E14 mouse embryos were electroporated in utero with GFP plasmids together with pSUPER vector or α2-chimaerin shRNA. Cortical slice cultures were prepared at E16 and the migration of GFP+ cells were monitored for 7 h. Red arrowheads, neurites extending from cell bodies. Pink arrowheads, swelling of leading process of the pSUPER electroporated neuron (see also Supplementary Movie 3). Scale bar, 20 μm. (b) Total number of process extension and retraction events was decreased in α2-chimaerin knockdown neurons (n = 20 neurons in each group). (c) The average neurite lifetime was shortened in α2-chimaerin knockdown neurons. **P < 0.01; Student's t-test (n = 79 and 72 neurites in pSUPER and α2-shRNA group, respectively). (d) Percentage of multipolar cells changing to bipolar shape in the imaging period. ***P < 0.001; Student's t-test (n = 82 and 79 neurons in pSUPER and α2-shRNA groups, respectively). (e) The migration rate of α2-chimaerin knockdown neurons was significantly reduced. Data are presented as migration distance divided by time. ***P < 0.001; Student's t-test. Error bars, s.e.m.

  3. [alpha]2-chimaerin knockdown results in accumulations of ectopic neurons in postnatal brain.
    Figure 3: α2-chimaerin knockdown results in accumulations of ectopic neurons in postnatal brain.

    (a) α2-chimaerin knockdown neurons stalled at the deep layers at P2. E14 mouse embryos were electroporated in utero with GFP plasmids together with pSUPER vector (pSUPER) or α2-chimaerin shRNA (α2-shRNA). Representative coronal brain sections at P2 were stained with antibodies to GFP (green) and Cutl1 (red), a layer II–IV marker, and counterstained with TO-PRO3 (blue). Arrows indicate the ectopic band of neurons. WM, white matter. Scale bar, 100 μm. (b) Layer distribution of pSUPER or α2-shRNA electroporated neurons. ***P < 0.001; Student's t-test. (c) Boxed regions from a at higher magnification. Scale bar, 20 μm. Despite the abnormal location, most of the α2-chimaerin knockdown neurons expressed Cutl1. (d) Silencing of α2-chimaerin caused an ectopic accumulation of neurons in the white matter at P19. Representative brain coronal sections were stained with antibodies to GFP (green) and NeuN (red), a neuronal marker, and counterstained with TO-PRO3 (blue). Scale bar, 100 μm. (e) Quantification of the layer distribution of GFP+ neurons in P19 cortex. **P < 0.01; ***P < 0.001; Student's t-test. (f,g) Boxed region from d at higher magnification for visualization of the white matter ectopic neurons, which were NeuN-positive. Scale bars, 20 μm. For b,e, more than 1,000 GFP+ neurons from three to five brains were analyzed in each group. Error bars, s.e.m.

  4. Mice with in utero suppression of [alpha]2-chimaerin show altered cortical excitability and show enhanced susceptibility to seizures.
    Figure 4: Mice with in utero suppression of α2-chimaerin show altered cortical excitability and show enhanced susceptibility to seizures.

    (ac) Increased spontaneous glutamatergic activity (sEPSCs) in the layer II–III cortex after in utero suppression of α2-chimaerin. (a) Representative traces of sEPSCs recorded at −70 mV. We recorded layer II–III pyramidal neurons of contralateral unelectroporated cortex (contra L II–III), pSUPER vector–electroporated cortex (pSUPER L II–III) or α2-chimaerin shRNA-electroporated cortex (α2-shRNA L II–III) at P15–20. We also recorded ectopic cells accumulated in the white matter after in utero electroporation of α2-shRNA (α2-shRNA WM). (b) Mean sEPSC frequencies in layer II–III pyramidal neurons of contra, pSUPER, α2-shRNA slices and white matter–trapped ectopic cells of α2-shRNA slices. (c) Mean sEPSC amplitudes in layer II–III pyramidal neurons of contra, pSUPER, α2-shRNA slices and white matter-trapped ectopic cells of α2-shRNA slices. The sEPSCs were sensitive to the AMPA-receptor antagonist CNQX, indicating that they were glutamatergic in nature (eight to ten neurons from three or four mice were analyzed in each group). (df) Mice with migration defects after α2-chimaerin knockdown were more susceptible to PTZ-induced seizures. We studied P30 mice with in utero electroporation of pSUPER or α2-shRNA, together with age-matched controls (six to eight mice from each group). Data are presented as cumulative PTZ doses (d), latency to induce generalized tonic-clonic seizures (e) and interval between minimal and generalized seizures (f). *P < 0.05, **P < 0.01, ***P < 0.001 versus pSUPER L II–III for b,c or versus pSUPER for df; Student's t-test. Error bars, s.e.m.

  5. The SH2 domain of [alpha]2-chimaerin is required for neuronal migration.
    Figure 5: The SH2 domain of α2-chimaerin is required for neuronal migration.

    (a) Expression of R73L α2-chimaerin did not rescue the migration defects after α2-chimaerin knockdown. E14 mouse embryos were electroporated in utero with α2-shRNA together with pCAG GFP vector only or GFP plasmids expressing α2-chimaerin wild-type (WT), R304G or R73L. Representative coronal sections at E17 were stained with antibodies to GFP (green) and counterstained with TO-PRO3 (blue). Scale bar, 50 μm. CP, cortical plate; IZ, intermediate zone. (b) Quantification of the distribution of GFP+ neurons expressing different α2-chimaerin mutants at E17. VZ, ventricular zone. ***P < 0.001 versus α2RNAi + pCAG vector group; Student's t-test. (c) Percentage of neurons in the IZ with uni- or bipolar morphology, no processes or multiple minor processes. ***P < 0.001; Student's t-test. (df) Overexpression of α2-SH2-c disrupted radial migration in the cerebral cortex. E14 mouse embryos were electroporated in utero with GFP vector or GFP plasmid expressing α2-SH2-c. (d) Representative coronal sections at E17 stained with antibodies to GFP (green) and counterstained with TO-PRO3 (blue). Scale bar, 50 μm. (e) Quantification of the distribution of GFP+ neurons at E17. ***P < 0.001 versus pCAG vector group; Student's t-test. (f) Quantification of cell morphology at intermediate zone after overexpression of α2-SH2-c. ***P < 0.001; Student's t-test. More than 1,000 cells for analyzing distribution of GFP+ cells, and more than 150 cells for morphological analysis from three to five brains in each group. Error bars, s.e.m.

  6. [alpha]2-chimaerin mediates neurotrophin-dependent regulation of CRMP-2 activity.
    Figure 6: α2-chimaerin mediates neurotrophin-dependent regulation of CRMP-2 activity.

    (a) Inhibition of Trk activity by K252a (250 nM) impaired migration of GFP+ electroporated cells in cortical slice cultures. Scale bar, 100 μm. CP, cortical plate; IZ, intermediate zone. (b) Quantification of the distribution of GFP+ cells in K252a-treated and control slices. VZ, ventricular zone. **P < 0.01, ***P < 0.001; Student's t-test. More than 1,000 cells from three brains were analyzed in each group. (c) α2-chimaerin (α2-CHN) interacted with TrkA, TrkB and TrkC. (d) α2-chimaerin interacted with TrkB in an SH2-dependent manner. WT, wild type; R73L, SH2 domain–mutated α2-chimaerin mutant. For c,d, HEK293T cells were transfected with combinations of α2-chimaerin and Trk plasmids as indicated, followed by co-immunoprecipitation (IP). (e) α2-chimaerin was recruited to TrkB in cortical neurons upon BDNF treatment. Cortical neurons (4 d in vitro) were treated with BDNF (100 ng ml1) at the indicated time points, followed by co-IP. Lys, lysate; IgG, immunoglobulin G. (f) α2-chimaerin regulated neurotrophin-mediated signaling. pSUPER- or α2-shRNA–transfected cortical neurons (4 d in vitro) were treated with BDNF or NT3 or were untreated (Con) (100 ng ml1) for 30 min. (gi) Quantification of tyrosine-phosphorylated (pTyr)-Trk (g), phosphorylated GSK-3β (pGSK-3β) (h) and pCRMP-2 (i) after α2-chimaerin knockdown and BDNF or NT3 treatment (Con, untreated) (fold change). **P < 0.01; Student's t-test. (j) Cortical neuron cultures (2 d in vitro) from cortex electroporated with GFP and pSUPER or α2-shRNA, stained for pCRMP-2 (red) and acetylated tubulin (ace-tub; blue). Scale bar, 20 μm. (k) α2-chimaerin knockdown neurons were characterized by the absence of one acetylated tubulin–positive neurite. Scale bar, 20 μm. Error bars, s.e.m.

  7. [alpha]2-chimaerin mediates neuronal migration through precise regulation of CRMP-2 activity.
    Figure 7: α2-chimaerin mediates neuronal migration through precise regulation of CRMP-2 activity.

    (a) In utero knockdown of CRMP-2 disrupted radial migration in the cerebral cortex. E14 mouse embryos were electroporated in utero with GFP plasmid together with CRMP-2 scrambled shRNA (scr) or CRMP-2 shRNA. Representative coronal sections at E17 were stained with GFP antibody (green) and counterstained with TO-PRO3 (blue). CP, cortical plate; IZ, intermediate zone. Scale bar, 100 μm. (b) Quantification of the distribution of GFP+ neurons at E17. VZ, ventricular zone. **P < 0.01; ***P < 0.001; Student's t-test. (c) Quantification of cell morphology in the IZ after CRMP-2 knockdown. ***P < 0.001; Student's t-test. (d) GFP plasmids expressing CRMP-2 wild-type (WT), T514A or T514E mutants or GFP vector only were electroporated in utero together with α2-chimaerin shRNA (α2-shRNA) at E14. Representative coronal sections at E17 were stained with antibodies to GFP (green) and counterstained with TO-PRO3 (blue). Scale bar, 100 μm. (e) Quantification of the distribution of GFP+ neurons at E17. ***P < 0.001 versus α2-shRNA + pCAG vector group; Student's t-test. (f) Quantification of cell morphology in the IZ. *P < 0.05, ***P < 0.001, versus α2-shRNA + pCAG vector group; Student's t-test. More than 1,000 cells for analysis of distribution of GFP+ cells, and more than 150 cells for morphological analysis from three to five brains in each group. Error bars, s.e.m.

References

  1. Guerrini, R., Sicca, F. & Parmeggiani, L. Epilepsy and malformations of the cerebral cortex. Epileptic Disord. 5 (suppl. 2), S9S26 (2003).
  2. Chang, B.S. & Walsh, C.A. The genetic basis of human cerebral cortical malformations. in Principles of Molecular Medicine Vol. XIII (eds. Runge, M.S. and Patterson, C.) 10731079 (Humana, 2006).
  3. Ayala, R., Shu, T. & Tsai, L.H. Trekking across the brain: the journey of neuronal migration. Cell 128, 2943 (2007).
  4. Valiente, M. & Marin, O. Neuronal migration mechanisms in development and disease. Curr. Opin. Neurobiol. 20, 6878 (2010).
  5. Gleeson, J.G. & Walsh, C.A. Neuronal migration disorders: from genetic diseases to developmental mechanisms. Trends Neurosci. 23, 352359 (2000).
  6. Deutsch, S.I., Burket, J.A. & Katz, E. Does subtle disturbance of neuronal migration contribute to schizophrenia and other neurodevelopmental disorders? Potential genetic mechanisms with possible treatment implications. Eur. Neuropsychopharmacol. 20, 281287 (2010).
  7. Singh, K.K. et al. Dixdc1 is a critical regulator of DISC1 and embryonic cortical development. Neuron 67, 3348 (2010).
  8. Wegiel, J. et al. The neuropathology of autism: defects of neurogenesis and neuronal migration, and dysplastic changes. Acta Neuropathol. 119, 755770 (2010).
  9. Nadarajah, B., Alifragis, P., Wong, R.O. & Parnavelas, J.G. Neuronal migration in the developing cerebral cortex: observations based on real-time imaging. Cereb. Cortex 13, 607611 (2003).
  10. Noctor, S.C., Martinez-Cerdeno, V., Ivic, L. & Kriegstein, A.R. Cortical neurons arise in symmetric and asymmetric division zones and migrate through specific phases. Nat. Neurosci. 7, 136144 (2004).
  11. LoTurco, J.J. & Bai, J. The multipolar stage and disruptions in neuronal migration. Trends Neurosci. 29, 407413 (2006).
  12. Tabata, H. & Nakajima, K. Multipolar migration: the third mode of radial neuronal migration in the developing cerebral cortex. J. Neurosci. 23, 999610001 (2003).
  13. Kawauchi, T. & Hoshino, M. Molecular pathways regulating cytoskeletal organization and morphological changes in migrating neurons. Dev. Neurosci. 30, 3646 (2008).
  14. Hall, C. et al. alpha2-chimaerin, a Cdc42/Rac1 regulator, is selectively expressed in the rat embryonic nervous system and is involved in neuritogenesis in N1E–115 neuroblastoma cells. J. Neurosci. 21, 51915202 (2001).
  15. Iwasato, T. et al. Rac-GAP alpha-chimerin regulates motor-circuit formation as a key mediator of EphrinB3/EphA4 forward signaling. Cell 130, 742753 (2007).
  16. Beg, A.A., Sommer, J.E., Martin, J.H. & Scheiffele, P. alpha2-Chimaerin is an essential EphA4 effector in the assembly of neuronal locomotor circuits. Neuron 55, 768778 (2007).
  17. Wegmeyer, H. et al. EphA4-dependent axon guidance is mediated by the RacGAP alpha2-chimaerin. Neuron 55, 756767 (2007).
  18. Shi, L. et al. Alpha2-chimaerin interacts with EphA4 and regulates EphA4-dependent growth cone collapse. Proc. Natl. Acad. Sci. USA 104, 1634716352 (2007).
  19. Miyake, N. et al. Human CHN1 mutations hyperactivate alpha2-chimaerin and cause Duane's retraction syndrome. Science 321, 839843 (2008).
  20. Bacchelli, E. et al. Screening of nine candidate genes for autism on chromosome 2q reveals rare nonsynonymous variants in the cAMP-GEFII gene. Mol. Psychiatry 8, 916924 (2003).
  21. Lencz, T. et al. Runs of homozygosity reveal highly penetrant recessive loci in schizophrenia. Proc. Natl. Acad. Sci. USA 104, 1994219947 (2007).
  22. Davidsson, J., Collin, A., Olsson, M.E., Lundgren, J. & Soller, M. Deletion of the SCN gene cluster on 2q24.4 is associated with severe epilepsy: an array-based genotype-phenotype correlation and a comprehensive review of previously published cases. Epilepsy Res. 81, 6979 (2008).
  23. Jacobs, K.M., Kharazia, V.N. & Prince, D.A. Mechanisms underlying epileptogenesis in cortical malformations. Epilepsy Res. 36, 165188 (1999).
  24. Ackman, J.B. et al. Abnormal network activity in a targeted genetic model of human double cortex. J. Neurosci. 29, 313327 (2009).
  25. Manent, J.B., Wang, Y., Chang, Y., Paramasivam, M. & LoTurco, J.J. Dcx reexpression reduces subcortical band heterotopia and seizure threshold in an animal model of neuronal migration disorder. Nat. Med. 15, 8490 (2009).
  26. Hall, C., Lim, L. & Leung, T. C1, see them all. Trends Biochem. Sci. 30, 169171 (2005).
  27. North, H.A. et al. Promotion of proliferation in the developing cerebral cortex by EphA4 forward signaling. Development 136, 24672476 (2009).
  28. Torii, M., Hashimoto-Torii, K., Levitt, P. & Rakic, P. Integration of neuronal clones in the radial cortical columns by EphA and ephrin-A signalling. Nature 461, 524528 (2009).
  29. Ohmiya, M. et al. Brain-derived neurotrophic factor alters cell migration of particular progenitors in the developing mouse cerebral cortex. Neurosci. Lett. 317, 2124 (2002).
  30. Medina, D.L. et al. TrkB regulates neocortex formation through the Shc/PLCgamma-mediated control of neuronal migration. EMBO J. 23, 38033814 (2004).
  31. Fukumitsu, H. et al. Brain-derived neurotrophic factor participates in determination of neuronal laminar fate in the developing mouse cerebral cortex. J. Neurosci. 26, 1321813230 (2006).
  32. Zhao, C.T. et al. PKCdelta regulates cortical radial migration by stabilizing the Cdk5 activator p35. Proc. Natl. Acad. Sci. USA 106, 2135321358 (2009).
  33. Fukata, Y. et al. CRMP-2 binds to tubulin heterodimers to promote microtubule assembly. Nat. Cell Biol. 4, 583591 (2002).
  34. Yoshimura, T. et al. GSK-3β regulates phosphorylation of CRMP-2 and neuronal polarity. Cell 120, 137149 (2005).
  35. Marín, O., Valiente, M., Ge, X. & Tsai, L.H. Guiding neuronal cell migrations. Cold Spring Harb. Perspect. Biol. 2, a001834 (2010).
  36. Bai, J. et al. RNAi reveals doublecortin is required for radial migration in rat neocortex. Nat. Neurosci. 6, 12771283 (2003).
  37. Tsai, J.W., Chen, Y., Kriegstein, A.R. & Vallee, R.B. LIS1 RNA interference blocks neural stem cell division, morphogenesis, and motility at multiple stages. J. Cell Biol. 170, 935945 (2005).
  38. Ohshima, T. et al. Cdk5 is required for multipolar-to-bipolar transition during radial neuronal migration and proper dendrite development of pyramidal neurons in the cerebral cortex. Development 134, 22732282 (2007).
  39. Arimura, N., Menager, C., Fukata, Y. & Kaibuchi, K. Role of CRMP-2 in neuronal polarity. J. Neurobiol. 58, 3447 (2004).
  40. Brown, M. et al. Alpha2-chimaerin, cyclin-dependent kinase 5/p35, and its target collapsin response mediator protein-2 are essential components in semaphorin 3A-induced growth-cone collapse. J. Neurosci. 24, 89949004 (2004).
  41. Pawson, T. Specificity in signal transduction: from phosphotyrosine-SH2 domain interactions to complex cellular systems. Cell 116, 191203 (2004).
  42. Bar, I., Lambert de Rouvroit, C. & Goffinet, A.M. The Reelin signaling pathway in mouse cortical development. Eur. J. Morphol. 38, 321325 (2000).
  43. Young-Pearse, T.L. et al. A critical function for beta-amyloid precursor protein in neuronal migration revealed by in utero RNA interference. J. Neurosci. 27, 1445914469 (2007).
  44. Chen, G. et al. Semaphorin-3A guides radial migration of cortical neurons during development. Nat. Neurosci. 11, 3644 (2008).
  45. Lapray, D. et al. Spontaneous epileptic manifestations in a DCX knockdown model of human double cortex. Cereb. Cortex 20, 26942701 (2010).
  46. Thomas, E.A. et al. Antipsychotic drug treatment alters expression of mRNAs encoding lipid metabolism-related proteins. Mol. Psychiatry 8, 98393, 950 (2003).
  47. Lo, K.Y. et al. SLAM-associated protein as a potential negative regulator in Trk signaling. J. Biol. Chem. 280, 4174441752 (2005).
  48. Itoh, Y., Masuyama, N., Nakayama, K., Nakayama, K.I. & Gotoh, Y. The cyclin-dependent kinase inhibitors p57 and p27 regulate neuronal migration in the developing mouse neocortex. J. Biol. Chem. 282, 390396 (2007).
  49. Racine, R.J. Modification of seizure activity by electrical stimulation. II. Motor seizure. Electroencephalogr. Clin. Neurophysiol. 32, 281294 (1972).
  50. Fu, W.Y. et al. Cdk5 regulates EphA4-mediated dendritic spine retraction through an ephexin1-dependent mechanism. Nat. Neurosci. 10, 6776 (2007).

Download references

Author information

  1. These authors contributed equally to this work.

    • Jacque P K Ip &
    • Lei Shi

Affiliations

  1. Division of Life Science, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.

    • Jacque P K Ip,
    • Lei Shi,
    • Yu Chen,
    • Wing-Yu Fu,
    • Amy K Y Fu &
    • Nancy Y Ip
  2. Molecular Neuroscience Center, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.

    • Jacque P K Ip,
    • Lei Shi,
    • Yu Chen,
    • Wing-Yu Fu,
    • Amy K Y Fu &
    • Nancy Y Ip
  3. State Key Laboratory of Molecular Neuroscience, The Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China.

    • Jacque P K Ip,
    • Lei Shi,
    • Yu Chen,
    • Wing-Yu Fu,
    • Amy K Y Fu &
    • Nancy Y Ip
  4. Institute of Molecular and Cellular Biosciences, The University of Tokyo, Tokyo, Japan.

    • Yasuhiro Itoh &
    • Yukiko Gotoh
  5. Department of Pathology, University of Otago at Christchurch, Christchurch, New Zealand.

    • Andrea Betz
  6. School of Biomedical Sciences, The Chinese University of Hong Kong, Hong Kong, China.

    • Wing-Ho Yung

Contributions

N.Y.I. supervised the project. J.P.K.I., L.S., Y.C., W.-Y.F., A.K.Y.F. and N.Y.I. designed the experiments. J.P.K.I. and L.S. conducted the majority of experiments. J.P.K.I., L.S., Y.C., A.K.Y.F. and N.Y.I. performed the data analyses. Y.I. and Y.G. provided technical support on in utero electroporation and live-imaging experiments. J.P.K.I. and Y.I. performed live-imaging experiments. W.-H.Y. performed the electrophysiology experiments and subsequent data analyses. A.B. provided Chn1−/− mice. J.P.K.I., L.S., A.K.Y.F. and N.Y.I. wrote the manuscript.

Competing financial interests

The authors declare no competing financial interests.

Corresponding author

Correspondence to:

Author details

Supplementary information

PDF files

  1. Supplementary Text and Figures (2M)

    Supplementary Figures 1–11

Movies

  1. Supplementary Video 1 (623K)

    This movie shows the migration of neurons electroporated with pSUPER vector and GFP plasmids. Most of the neurons attained bipolar shape, underwent nuclear translocation and migrated up to the cortical plate. Images were captured every 15 min for 13 h.

  2. Supplementary Video 2 (606K)

    This movie shows the migration of neurons electroporated with α2-chimerin shRNA and GFP plasmids. α2-chimerin knockdown neurons were unable to enter into the cortical plate, and showed local movement within the intermediate zone. Images were captured every 15 min for 13 h.

  3. Supplementary Video 3 (602K)

    This movie shows an example of migrating neurons electroporated with pSUPER vector and GFP plasmids. The neuron extended and retracted neurites actively, and eventually formed one major leading process guiding the migration of cell body towards pial surface. Images were captured every 10 min for 7 h.

  4. Supplementary Video 4 (627K)

    This movie shows an example of migrating neurons electroporated with α2-chimerin shRNA and GFP plasmids. The neuron showed impaired neurite dynamics and failed to form a leading process towards pial surface. Images were captured every 10 min for 7 h.

Additional data