TREM2 Gene Dosage Increase Reprograms Microglia Responsivity and Ameliorates Pathological Phenotypes in Alzheimer’s Disease Models

TREM2 BAC transgenic mice with elevated expression of human TREM2 in microglia under its endogenous regulation without overexpression of other TREM-like genes on the BAC were generated and crossed with 5xFAD mice, an mouse model of AD. Transcriptome and gene coexpression analyses were performed to obtain chronical view of TREM gene dosage dependent changes in the context of amyloid pathology. The results confer strong evidence that increased TREM2 alters brain transcriptome network response only in the context of a disease state and with an overall rescuing effect in 5xFAD mice. Brain cortical tissues were dissected from WT, BAC-TREM2, 5xFAD and 5xFAD/BAC-TREM2 at 2, 4 and 7 months of age. RNA was extracted using Qiagen RNeasy kit. Libraries prepared using the Illumina TruSeq RNA Library Prep Kit v2 and sequenced on an Illumina HiSeq4000 sequencer using strand-specific, paired-end, 69-mer sequencing protocols to a minimum read depth of 30 million reads per sample. Reads were aligned to mouse genome mm10 using the STAR aligner with default settings. Read counts for individual genes were obtained using HTSeq.