1. Evolution of Cortical Neurogenesis in Amniotes Controlled by Robo Signaling Levels.
- Author
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Cárdenas A, Villalba A, de Juan Romero C, Picó E, Kyrousi C, Tzika AC, Tessier-Lavigne M, Ma L, Drukker M, Cappello S, and Borrell V
- Subjects
- Animals, Calcium-Binding Proteins, Cerebral Cortex metabolism, Chick Embryo, Gene Expression Regulation, Developmental genetics, Homeodomain Proteins, Humans, Intercellular Signaling Peptides and Proteins genetics, Jagged-1 Protein, Jagged-2 Protein, Mammals embryology, Mice, Mice, Inbred C57BL, Neocortex physiology, Neural Stem Cells, Neurogenesis physiology, Neuroglia physiology, Neurons, PAX6 Transcription Factor metabolism, Repressor Proteins, Signal Transduction, Snakes embryology, Roundabout Proteins, Intercellular Signaling Peptides and Proteins metabolism, Nerve Tissue Proteins genetics, Nerve Tissue Proteins metabolism, Neurogenesis genetics, Receptors, Immunologic genetics, Receptors, Immunologic metabolism
- Abstract
Cerebral cortex size differs dramatically between reptiles, birds, and mammals, owing to developmental differences in neuron production. In mammals, signaling pathways regulating neurogenesis have been identified, but genetic differences behind their evolution across amniotes remain unknown. We show that direct neurogenesis from radial glia cells, with limited neuron production, dominates the avian, reptilian, and mammalian paleocortex, whereas in the evolutionarily recent mammalian neocortex, most neurogenesis is indirect via basal progenitors. Gain- and loss-of-function experiments in mouse, chick, and snake embryos and in human cerebral organoids demonstrate that high Slit/Robo and low Dll1 signaling, via Jag1 and Jag2, are necessary and sufficient to drive direct neurogenesis. Attenuating Robo signaling and enhancing Dll1 in snakes and birds recapitulates the formation of basal progenitors and promotes indirect neurogenesis. Our study identifies modulation in activity levels of conserved signaling pathways as a primary mechanism driving the expansion and increased complexity of the mammalian neocortex during amniote evolution., (Copyright © 2018 The Authors. Published by Elsevier Inc. All rights reserved.)
- Published
- 2018
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