title: Dissecting the factors involved in the locomotion mode of neuronal migration in the developing cerebral cortex.
abstract: Neuronal migration is essential for proper cortical layer formation and brain function, because migration defects result in neurological disorders such as mental retardation and epilepsy. Neuronal migration is divided into several contiguous steps: early phase (multipolar mode), locomotion mode, and terminal translocation mode. The locomotion mode covers most of the migration route and thereby is the main contributor to cortical layer formation. However, analysis of the molecular mechanisms regulating this mode is difficult due to the secondary effects of defects at the early phase of migration. In this study, we established an ex vivo chemical inhibitor screening, allowing us to directly analyze the locomotion mode of migration. Roscovitine and PP2, inhibitors for Cdk5 and Src family kinases, respectively, suppressed the locomotion mode of migration. In line with this, a small percentage of Cdk5- or Src family kinase (Fyn)-knockdown cells exhibited locomoting morphology but retarded migration, although the majority of cells were stalled at the early phase of migration. We also showed that rottlerin, widely used as a specific inhibitor for protein kinase Cdelta (PKCdelta), suppressed the locomotion mode. Unexpectedly, however, the dominant-negative form as well as RNA interference for PKCdelta hardly affected the locomotion, whereas they may disturb terminal translocation. In addition, we found JNK to be a potential downstream target of rottlerin. Taken together, our novel chemical inhibitor screening provides evidence that Cdk5 and Src family kinases regulate the locomotion mode of neuronal migration. It also uncovered roles for Fyn and PKCdelta in the early and final phases of migration, respectively.
authors.affiliation: Department of Anatomy, School of Medicine, Keio University, 35 Shinanomachi, Shinjuku-ku, Tokyo 160-8582, Japan.
authors.forename: Yoshiaki V
authors.initials: YV
authors.lastname: Nishimura
authors.forename: Katsutoshi
authors.initials: K
authors.lastname: Sekine
authors.forename: Kaori
authors.initials: K
authors.lastname: Chihama
authors.forename: Kazunori
authors.initials: K
authors.lastname: Nakajima
authors.forename: Mikio
authors.initials: M
authors.lastname: Hoshino
authors.forename: Yo-ichi
authors.initials: Y
authors.lastname: Nabeshima
authors.forename: Takeshi
authors.initials: T
authors.lastname: Kawauchi
mesh_terms: D000818:Animals; D002465:Cell Movement / Q000187:drug effects / Q000502:physiology*; D002540:Cerebral Cortex / Q000196:embryology* / Q000201:enzymology*; D051360:Cyclin-Dependent Kinase 5 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D005260:Female; D048670:MAP Kinase Kinase 4 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D051379:Mice; D008813:Mice, Inbred ICR; D009474:Neurons / Q000201:enzymology*; D011247:Pregnancy; D051745:Protein Kinase C-delta / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D051076:Proto-Oncogene Proteins c-fyn / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D011687:Purines / Q000494:pharmacology; D011743:Pyrimidines / Q000494:pharmacology; D000077546:Roscovitine
chemical_list: C412373:AG 1879; D047428:Protein Kinase Inhibitors; D011687:Purines; D011743:Pyrimidines; D000077546:Roscovitine; C497259:Prkcd protein, mouse; C494960:Fyn protein, mouse; D051076:Proto-Oncogene Proteins c-fyn; D051360:Cyclin-Dependent Kinase 5; D051745:Protein Kinase C-delta; C495906:Cdk5 protein, mouse; D048670:MAP Kinase Kinase 4