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Undisturbed climbing fiber pruning in the cerebellar cortex of CX 3 CR1 ‐deficient mice
Author(s) -
Kaiser Nicole,
Pätz Christina,
Brachtendorf Simone,
Eilers Jens,
Bechmann Ingo
Publication year - 2020
Publication title -
glia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.954
H-Index - 164
eISSN - 1098-1136
pISSN - 0894-1491
DOI - 10.1002/glia.23842
Subject(s) - synaptic pruning , neuroscience , cx3cr1 , cerebellar cortex , biology , synapse , parallel fiber , microglia , climbing fiber , cerebellum , microbiology and biotechnology , receptor , immunology , chemokine , inflammation , chemokine receptor , genetics
Pruning, the elimination of excess synapses is a phenomenon of fundamental importance for correct wiring of the central nervous system. The establishment of the cerebellar climbing fiber (CF)‐to‐Purkinje cell (PC) synapse provides a suitable model to study pruning and pruning‐relevant processes during early postnatal development. Until now, the role of microglia in pruning remains under intense investigation. Here, we analyzed migration of microglia into the cerebellar cortex during early postnatal development and their possible contribution to the elimination of CF‐to‐PC synapses. Microglia enrich in the PC layer at pruning‐relevant time points giving rise to the possibility that microglia are actively involved in synaptic pruning. We investigated the contribution of microglial fractalkine (CX 3 CR1) signaling during postnatal development using genetic ablation of the CX 3 CR1 receptor and an in‐depth histological analysis of the cerebellar cortex. We found an aberrant migration of microglia into the granule and the molecular layer. By electrophysiological analysis, we show that defective fractalkine signaling and the associated migration deficits neither affect the pruning of excess CFs nor the development of functional parallel fiber and inhibitory synapses with PCs. These findings indicate that CX 3 CR1 signaling is not mandatory for correct cerebellar circuit formation. Main Points Ablation of CX 3 CR1 results in a transient migration defect in cerebellar microglia. CX 3 CR1 is not required for functional pruning of cerebellar climbing fibers. Functional inhibitory and parallel fiber synapse development with Purkinje cells is undisturbed in CX 3 CR1‐deficient mice.