GDF3 promotes adipose tissue macrophage-mediated inflammation via altered chromatin accessibility during aging

SMAD2/3 transcription factors (TFs) have low DNA binding affinity for a specific consensus sequence, allowing them to elicit anti- or pro-inflammatory responses depending on the cellular context. Genes associated with pro-inflammatory processes in immune cells, including myeloid cells, exhibit increased chromatin accessibility with age. We hypothesized that this could affect the transcriptional activity of SMAD2/3 in adipose tissue macrophages (ATMs). To assess chromatin accessibility, ATMs isolated using fluorescence-activated cell sorting (FACS) from young control, old control and old mKO mice were profiled using assay for ATAC-seq. Overall design: Visceral adipose tissue depots were isolated from mice and digested into stromal vascular fraction and adipocyte fraction (PMID: 33870227). Then, the stromal vascular fraction was used for fluorescence-activated cell sorting of adipose tissue macrophages: Live CD45+ CD11b+ SiglecF- F4/80+ cells were sorted on a BD FACS Aria II into RPMI with 20% FBS