The effect of microglial STAT3 signaling on early postnatal brain development

Microglia play critical roles in the maturation and refinement of neural networks of the developing brain. The goal of this study was to investigate the role of microglial STAT3 in postnatal brain development. This experiment was aimed to determine gene profiles (RNA-seq) of wild-type and Stat3 mutant microglia. Cx3cr1CreERT2/+:Stat3loxP mice were generated to achieve tamoxifen-inducible deletion of exon 22 of the Stat3 gene in microglia. mRNA was prepared from acutely isolated microglia from postnatal day 8 (P8) pups that received tamoxifen from postnatal day 1 to 3. Overall, we found that Stat3 mutant produced signficantly higher levels of inlfammatory cytokines and had compromised DNA damage checkpoints. Cx3cr1CreERT2/+:Stat3fl/fl mice received daily tamoxifen from P1-P3. CD11b+ cells were isolated by percoll gradient centrifugation and FACS sorting from P8 forebrains of Stat3 conditional knockout (Cx3cr1-CreERT/+: Stat3 fl/fl) and littermate controls (Stat3fl/fl). Each sample represents a pool of 2-4 pups (both sexes) with the same genotype. TruSeqRNA Sample Prep Kit (Illumina) was used for poly A mRNA selection and library preparation. Fourty base-pair reads were generated for each sample on an Illumina HiSeq 2500 instrument at the Whitehead Institute Genome Technology core facility. A total of 286 million reads were mapped against GRCm38/mm10 assembly using TopHat version 2.0.13 with default settings, out of which a total of 274 million reads (approximately 95%) were aligned to the reference genome.