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Updated: Apr 25, 2026
Author Spotlight: Exploring Cell Migration and Gene Roles in the Developing Brain
Published on: March 8, 2024
Microglia modulate wiring of the embryonic forebrain
Paola Squarzoni1, Guillaume Oller1, Guillaume Hoeffel2
1École Normale Supérieure, Institut de Biologie de l'ENS, IBENS, INSERM, U1024, CNRS, UMR 8197, Brain Development and Plasticity Team, 46 rue d'Ulm, 75230 Paris Cedex 05, France.
Abstract:
Dysfunction of microglia, the tissue macrophages of the brain, has been associated with the etiology of several neuropsychiatric disorders. Consistently, microglia have been shown to regulate neurogenesis and synaptic maturation at perinatal and postnatal stages. However, microglia invade the brain during mid-embryogenesis and thus could play an earlier prenatal role. Here, we show that embryonic microglia, which display a transiently uneven distribution, regulate the wiring of forebrain circuits. Using multiple mouse models, including cell-depletion approaches and cx3cr1(-/-), CR3(-/-), and DAP12(-/-) mutants, we find that perturbing microglial activity affects the outgrowth of dopaminergic axons in the forebrain and the laminar positioning of subsets of neocortical interneurons. Since defects in both dopamine innervation and cortical networks have been linked to neuropsychiatric diseases, our study provides insights into how microglial dysfunction can impact forebrain connectivity and reveals roles for immune cells during normal assembly of brain circuits.
Insights
Embryonic microglia regulate brain wiring by influencing dopaminergic axon growth and neuron positioning. This reveals a prenatal role for these immune cells in forebrain circuit development and neuropsychiatric disease etiology.
Area of Science:
- Neuroscience
- Immunology
- Developmental Biology
Background:
- Microglia, the brain's immune cells, are implicated in neuropsychiatric disorders.
- Microglia are known to influence neurogenesis and synaptic maturation postnatally.
- Microglia enter the brain during mid-embryogenesis, suggesting a potential prenatal role.
Purpose of the Study:
- To investigate the prenatal role of microglia in brain circuit development.
- To determine how embryonic microglia influence forebrain circuit wiring.
Main Methods:
- Utilized mouse models, including cell-depletion strategies.
- Employed genetic mutants such as cx3cr1(-/-), CR3(-/-), and DAP12(-/-).
- Analyzed microglial distribution and its impact on neuronal development.
Main Results:
- Embryonic microglia exhibit a transiently uneven distribution in the developing brain.
- Perturbing microglial activity affected dopaminergic axon outgrowth in the forebrain.
- Microglial function influenced the laminar positioning of neocortical interneurons.
Conclusions:
- Embryonic microglia play a crucial role in regulating the wiring of forebrain circuits.
- Microglial dysfunction during prenatal development can impact brain connectivity.
- This study highlights the involvement of immune cells in the early assembly of brain circuits, offering insights into neuropsychiatric disease origins.
