A phosphatidylinositol lipids system, lamellipodin, and Ena/VASP regulate dynamic morphology of multipolar migrating cells in the developing cerebral cortex.
In the developing mammalian cerebral cortex, excitatory neurons are generated in the ventricular zone (VZ) and subventricular zone; these neurons migrate toward the pial surface. The neurons generated in the VZ assume a multipolar morphology and remain in a narrow region called the multipolar cell accumulation zone (MAZ) for ∼24 h, in which they extend and retract multiple processes dynamically. They eventually extend an axon tangentially and begin radial migration using a migratory mode called locomotion. Despite the potential biological importance of the process movement of multipolar cells, the molecular mechanisms remain to be elucidated. Here, we observed that the processes of mouse multipolar cells were actin rich and morphologically resembled the filopodia and lamellipodia in growth cones; thus, we focused on the actin-remodeling proteins Lamellipodin (Lpd) and Ena/vasodilator-stimulated phosphoprotein (VASP). Lpd binds to phosphatidylinositol (3,4)-bisphosphate [PI(3,4)P₂] and recruits Ena/VASP, which promotes the assembly of actin filaments, to the plasma membranes. In situ hybridization and immunohistochemistry revealed that Lpd is expressed in multipolar cells in the MAZ. The functional silencing of either Lpd or Ena/VASP decreased the number of primary processes. Immunostaining and a Förster resonance energy transfer analysis revealed the subcellular localization of PI(3,4)P₂ at the tips of the processes. A knockdown experiment and treatment with an inhibitor for Src homology 2-containing inositol phosphatase-2, a 5-phosphatase that produces PI(3,4)P₂ from phosphatidylinositol (3,4,5)-triphosphate, decreased the number of primary processes. Our observations suggest that PI(3,4)P₂, Lpd, and Ena/VASP are involved in the process movement of multipolar migrating cells.
Department of Anatomy, Keio University School of Medicine, Shinjuku-ku, Tokyo 160-8582, Japan.
Satoshi
S
Yoshinaga
Takahiro
T
Ohkubo
Shinji
S
Sasaki
Mutsuo
M
Nuriya
Yukino
Y
Ogawa
Masato
M
Yasui
Hidenori
H
Tabata
Kazunori
K
Nakajima
D000199:Actins / Q000378:metabolism; D000818:Animals; D002352:Carrier Proteins / Q000235:genetics / Q000378:metabolism*; D015815:Cell Adhesion Molecules / Q000235:genetics / Q000378:metabolism*; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism; D002465:Cell Movement / Q000235:genetics / Q000502:physiology*; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology* / Q000196:embryology*; D002522:Chlorocebus aethiops; D018274:Electroporation; D004622:Embryo, Mammalian; D005260:Female; D005434:Flow Cytometry; D018507:Gene Expression Regulation, Developmental / Q000235:genetics; D049452:Green Fluorescent Proteins / Q000235:genetics; D020439:Growth Cones / Q000378:metabolism; D006801:Humans; D047468:Immunoprecipitation; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008813:Mice, Inbred ICR; D008840:Microfilament Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation / Q000235:genetics; D009474:Neurons / Q000166:cytology / Q000502:physiology*; D009924:Organ Culture Techniques; D010716:Phosphatidylinositols / Q000235:genetics / Q000378:metabolism; D010750:Phosphoproteins / Q000235:genetics / Q000378:metabolism*; D011247:Pregnancy; D011554:Pseudopodia / Q000235:genetics / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics / Q000378:metabolism; D018709:Statistics, Nonparametric; D013347:Subcellular Fractions / Q000378:metabolism; D059008:Time-Lapse Imaging; D014162:Transfection; D000098662:Vasodilator-Stimulated Phosphoprotein
D000199:Actins; D002352:Carrier Proteins; D015815:Cell Adhesion Molecules; D008565:Membrane Proteins; D008840:Microfilament Proteins; D010716:Phosphatidylinositols; D010750:Phosphoproteins; C493339:RAPH1 protein, human; D012333:RNA, Messenger; D034741:RNA, Small Interfering; C485184:enhanced green fluorescent protein; C118301:phosphoinositide-3,4-bisphosphate; D000098662:Vasodilator-Stimulated Phosphoprotein; D049452:Green Fluorescent Proteins