Microglia development follows a stepwise program to regulate brain homeostasis - Single Cell RNA-seq

Microglia play important roles in life-long brain maintenance and in pathology, but are also crucial in the developing central nervous system; yet their regulatory dynamics during development have not been fully elucidated. Genome-wide chromatin and expression profiling coupled with single-cell transcriptomic analysis throughout development reveal that microglia undergo three temporal developmental stages in synchrony with the brain: early, pre-, and adult microglia, which are under the control of distinct regulatory circuits. Knockout of the transcription factor MafB caused disruption of homeostasis in adulthood and increased inflammation. Environmental perturbations, such as the microbiome or prenatal immune activation, led to dysregulation of the developmental program, particularly in terms of inflammation. Together, our work identifies a stepwise developmental program of microglia integrating immune response pathways that may be associated with several neurodevelopmental disorders. Yolk sac progenitors (CD45+CD11B+CX3CR1-GFP+), microglia from early brain (CD45+CD11B+CX3CR1-GFP+), and microglia from later stages (CD45intCD11BintCX3CR1-GFP+) were isolated from CX3CR1+ C57BL/6J mice