Primary adventitial fibroblast response to TGFb is dependent on vascular site and implicates functional developmental epigenomic memory

We have shown that vascular SMCs, fibroblasts, and endothelial cells have transcriptional and epigenomic features that are distinct to vascular site. Further, TF motif accessibility analysis in fibroblasts reveals an increased accessibility of AP1, and SMAD2:3:4, and TCF21 motifs in the ascending fibroblast population compared to carotid and descending fibroblasts, with further gene regulatory network analysis suggesting distinct regulatory TF module activity in ascending fibroblasts highlighting master regulator of fibroblast activation Meox1. This differential chromatin accessibility would suggest the potential for heightened biological response to TGFb in ascending fibroblasts. To evaluate the functional effect of this differential chromatin accessibility and to identify if differential gene expression is retained following removal from vascular site flow conditions, we isolated and cultured primary adventitial fibroblasts from healthy 14 week old C57BL/6 mice from the ascending and descending aorta and stimulated them with control or TGFb (10ng/mL, 48hrs) and performed bulk RNA sequencing (n = 3 per condition).