CSF-1 controls cerebellar microglia and is required for motor function and social interaction

Area of Science:

• Neuroscience
• Immunology
• Cell Biology

Background:

• Microglia, the brain's resident macrophages, are vital for shaping neuronal circuits in the forebrain.
• The specific roles and characteristics of microglia within the cerebellum remain largely unexplored.

Purpose of the Study:

• To investigate the unique molecular identity and function of cerebellar microglia.
• To elucidate the signaling pathways regulating cerebellar microglial identity and their impact on neuronal circuits and behavior.

Main Methods:

• Comparative transcriptomic analysis of human and mouse cerebellar microglia versus forebrain microglia.
• Genetic manipulation to deplete CSF-1 in Nestin-expressing cells and assess effects on microglia.
• Assessment of Purkinje cell numbers, neuronal function, motor learning, and social novelty interactions.

Main Results:

• Cerebellar microglia exhibit a distinct molecular signature compared to forebrain microglia, driven by CSF-1 (colony-stimulating factor 1).
• CSF-1, not IL-34, is essential for maintaining cerebellar microglial populations and their transcriptional profile.
• CSF-1 depletion led to cerebellar microglial reduction, Purkinje cell loss, impaired neuronal function, and deficits in motor learning and social behavior.

Conclusions:

• Cerebellar microglial identity is regulated by a unique CSF-1/CSF-1R signaling pathway.
• This pathway is critical for maintaining cerebellar integrity, neuronal function, motor learning, and social behaviors.