Tbr2-positive intermediate (basal) neuronal progenitors safeguard cerebral cortex expansion by controlling amplification of pallial glutamatergic neurons and attraction of subpallial GABAergic interneurons.
Little is known about how, during its formidable expansion in development and evolution, the cerebral cortex is able to maintain the correct balance between excitatory and inhibitory neurons. In fact, while the former are born within the cortical primordium, the latter originate outward in the ventral pallium. Therefore, it remains to be addressed how these two neuronal populations might coordinate their relative amounts in order to build a functional cortical network. Here, we show that Tbr2-positive cortical intermediate (basal) neuronal progenitors (INPs) dictate the migratory route and control the amount of subpallial GABAergic interneurons in the subventricular zone (SVZ) through a non-cell-autonomous mechanism. In fact, Tbr2 interneuron attractive activity is moderated by Cxcl12 chemokine signaling, whose forced expression in the Tbr2 mutants can rescue, to some extent, SVZ cell migration. We thus propose that INPs are able to control simultaneously the increase of glutamatergic and GABAergic neuronal pools, thereby creating a simple way to intrinsically balance their relative accumulation.
Sessa
Alessandro
A
Division of Neuroscience, San Raffaele Scientific Institute, Milan 20132, Italy.
Mao
Chai-An
CA
Colasante
Gaia
G
Nini
Alessandro
A
Klein
William H
WH
Broccoli
Vania
V
D000818:Animals; D002465:Cell Movement; D002540:Cerebral Cortex / Q000166:cytology / Q000254:growth & development / Q000378:metabolism; D054377:Chemokine CXCL12 / Q000235:genetics / Q000378:metabolism; D018507:Gene Expression Regulation, Developmental; D007395:Interneurons / Q000166:cytology / Q000378:metabolism*; D051379:Mice; D008810:Mice, Inbred C57BL; D009474:Neurons / Q000166:cytology* / Q000378:metabolism*; D015398:Signal Transduction; D013234:Stem Cells / Q000378:metabolism*; D020825:T-Box Domain Proteins / Q000235:genetics / Q000378:metabolism*
D054377:Chemokine CXCL12; C515256:Cxcl12 protein, mouse; C491198:Eomes protein, mouse; D020825:T-Box Domain Proteins