Altered speeds and trajectories of neurons migrating in the ventricular and subventricular zones of the reeler neocortex.
The Reelin signaling pathway is essential for proper cortical development, but it is unclear to whether Reelin function is primarily important for cortical layering or neuron migration. It has been proposed that Reelin is perhaps required only for somal translocation but not glial-dependent locomotion. This implies that the location of neurons responding to Reelin is restricted to the outer regions of the cortical plate (CP). To determine whether Reelin is required for migration outside of the CP, we used time-lapse imaging to track the behavior of cells undergoing locomotion in the germinal zones. We focused on the migratory activity in the ventricular/subventricular zones where the first transition of bipolar to multipolar migration occurs and where functional Reelin receptors are known to be expressed. Despite Reelin loss, neurons had no difficulty in undergoing radial migration and indeed displayed greater migratory speed. Additionally, compared with the wild-type, reeler neurons displayed altered trajectories with greater deviation from a radial path. These results suggest that Reelin loss has early consequences for migration in the germinal zones that are portrayed as defective radial trajectories and migratory speeds. Together, these abnormalities can give rise to the increased cell dispersion observed in the reeler cortex.
Britto
Joanne M
JM
Howard Florey Institute, Florey Neuroscience Institutes, Parkville, Victoria 3010, Australia. joanne.britto@florey.edu.au
Tait
Karen J
KJ
Johnston
Leigh A
LA
Hammond
Vicki E
VE
Kalloniatis
Michael
M
Tan
Seong-Seng
SS
D000818:Animals; D015816:Cell Adhesion Molecules, Neuronal / Q000172:deficiency* / Q000235:genetics; D002465:Cell Movement / Q000235:genetics*; D016326:Extracellular Matrix Proteins / Q000172:deficiency* / Q000235:genetics; D051379:Mice; D008818:Mice, Neurologic Mutants; D019579:Neocortex / Q000166:cytology* / Q000378:metabolism / Q000473:pathology; D009419:Nerve Tissue Proteins / Q000172:deficiency* / Q000235:genetics; D009421:Nervous System Malformations / Q000235:genetics / Q000378:metabolism / Q000503:physiopathology; D009474:Neurons / Q000166:cytology / Q000473:pathology* / Q000502:physiology; D009924:Organ Culture Techniques; D000091042:Reelin Protein; D012697:Serine Endopeptidases / Q000172:deficiency* / Q000235:genetics; D009435:Synaptic Transmission / Q000235:genetics
D015816:Cell Adhesion Molecules, Neuronal; D016326:Extracellular Matrix Proteins; D009419:Nerve Tissue Proteins; D000091042:Reelin Protein; C000717128:Reln protein, mouse; D012697:Serine Endopeptidases