Modification of adipose mass by targeting distal enhancers of Ptrf.

Background: Adipose tissue plays a central role in systemically metabolic regulation. Polymerase I and transcript release factor (PTRF) is responsible for caveolae structure formation and plays a crucial role in lipid metabolism.

Results: We investigated the possibility of modifying adipose mass by targeting the enhancers of Ptrf. Single-nucleus transcriptomic analysis revealed that the reduction in fat mass caused by Ptrf knockout is associated with impaired adipogenesis and differentiation, adipocyte metabolism, nutrient transportation, and altered regulatory network. We demonstrated a closely positive association between Ptrf transcription and adipose mass in mice. Then, circular chromosome conformation capture sequencing and ChIP-seq data of mature adipocytes identified six candidate enhancers (E1-E6) of Ptrf, and the dual-luciferase reporting system revealed the transcriptional activity of three active candidate enhancers (E1, E3, E5) in Human embryonic kidney 293 (HEK293) and mouse embryo fibroblast (3T3-L1) cells. During the adipogenic differentiation of 3T3-L1, the epigenetic perturbation of these enhancers with the dCas9-KRAB system demonstrated their important roles during adipogenesis, with inhibited Ptrf expression and decreased lipid droplets and triglyceride contents. Injecting lentivirus carrying the dCas9-KRAB system into the inguinal fat of mice downregulated Ptrf expression and decreased body weight, body adipose percentage, and adipocyte diameter in vivo. Additionally, we observed the close binding of Pparg and Cebpa to Ptrf-E1.

Conclusions: Taken together, these findings identify the mechanism by which Ptrf deletion leads to reduced fat mass in mice, and indicate that adipose mass may be reduced by targeting cis-regulatory elements of key adipogenesis-related genes.