Robo1 regulates the migration and laminar distribution of upper-layer pyramidal neurons of the cerebral cortex.
Laminar organization is a key feature of the mammalian cerebral cortex, but the mechanisms by which final positioning and "inside-out" distribution of neurons are determined remain largely unknown. Here, we demonstrate that Robo1, a member of the family of Roundabout receptors, regulates the correct positioning of layers II/III pyramidal neurons in the neocortex. Specifically, we used RNA interference in mice to suppress the expression of Robo1 in a subset of layers II/III neurons, and observed the positions of these cells at distinct developmental stages. In contrast to control neurons that migrated toward the pial surface by P1, Robo1-suppressed neurons exhibited a delay in entering the cortical plate at respective stages. Unexpectedly, after the first postnatal week, these neurons were predominantly located in the upper part of layers II/III, in contrast to control cells that were distributed throughout these layers. Sequential electroporation studies revealed that Robo1-suppressed cells failed to establish the characteristic inside-out neuronal distribution and, instead, they accumulated beneath the marginal zone regardless of their birthdate. These results demonstrate that Robo receptors play a crucial role in neocortical lamination and particularly in the positioning of layers II/III pyramidal neurons.
Laboratory for Neocortical Development, RIKEN Center for Developmental Biology, Kobe 650-0047, Japan.
Yuko
Y
Gonda
William D
WD
Andrews
Hidenori
H
Tabata
Takashi
T
Namba
John G
JG
Parnavelas
Kazunori
K
Nakajima
Shinichi
S
Kohsaka
Carina
C
Hanashima
Shigeo
S
Uchino
D000367:Age Factors; D000818:Animals; D000831:Animals, Newborn; D019556:COS Cells; D002465:Cell Movement / Q000235:genetics*; D002540:Cerebral Cortex / Q000166:cytology* / Q000196:embryology / Q000254:growth & development; D002522:Chlorocebus aethiops; D003857:Deoxyuridine / Q000031:analogs & derivatives / Q000378:metabolism; D005260:Female; D005434:Flow Cytometry; D018507:Gene Expression Regulation, Developmental / Q000235:genetics* / Q000502:physiology; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D018398:Homeodomain Proteins / Q000378:metabolism; D007211:Indoles / Q000378:metabolism; D051379:Mice; D008813:Mice, Inbred ICR; D018345:Mice, Knockout; D009419:Nerve Tissue Proteins / Q000172:deficiency / Q000378:metabolism*; D009687:Nuclear Proteins / Q000378:metabolism; D011247:Pregnancy; D017966:Pyramidal Cells / Q000502:physiology*; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism; D011971:Receptors, Immunologic / Q000172:deficiency / Q000378:metabolism*; D012097:Repressor Proteins / Q000378:metabolism; D014162:Transfection; D000097905:Roundabout Proteins
D003857:Deoxyuridine; D049452:Green Fluorescent Proteins; D018398:Homeodomain Proteins; D007211:Indoles; D009419:Nerve Tissue Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D011971:Receptors, Immunologic; D012097:Repressor Proteins; D000097905:Roundabout Proteins; C000624101:Cux1 protein, mouse; C498888:Robo2 protein, mouse; C485184:enhanced green fluorescent protein; C007293:DAPI; C031086:5-ethynyl-2'-deoxyuridine