Tcf21 functions as a rate‐limiting factor during visceral adipose tissue development

Abstract

White adipose tissue plays an important role in energy storage. Excessive adiposity especially in the visceral adipose depot however has a stronger correlation with metabolic diseases such as insulin resistance. The specific anatomical locations of the visceral adipose tissue (VAT) suggest that it is subjective to depot-specific regulation during development. Here, using a specific inducible lineage-tracing mouse line, we identified that Tcf21 is specifically expressed in VAT but not in subcutaneous tissue. In VAT, Tcf21 is expressed in mesenchymal progenitor cells but not in differentiated adipocytes. Tcf21 lineage cells actively proliferate followed by differentiation into adipocytes during neonatal development but have a limited adipogenic capacity in adult mice even after high-fat diet treatment. Bulk RNAseq and ATACseq analyses of Tcf21 lineage cells isolated from mice of different ages revealed the dynamic gene expression and chromatin accessibility in Tcf21 lineage cells. In particular, elevated expression of inflammatory genes and fibrotic genes were observed in Tcf21 lineage cells as the adiposity of mice increased. Using the transcriptomic and motif enrichment data, we predicted a gene regulatory network mediating the gene expression changes in Tcf21 lineage cells. Single-cell RNAseq (scRNAseq) and immunostaining identified multiple subpopulations of Tcf21 lineage cells including 2 major subpopulations consisting of a mesothelial subpopulation and an interstitial subpopulation, as well as a small population that expressed select inflammatory genes exclusively in obese mice. Using an inducible cell-type-specific Tcf21 knockout mouse line, we identified that neonatal deletion of Tcf21 in mice led to increased adipogenesis of Tcf21 lineage cells during postnatal development and improved metabolism after high-fat diet treatment. In vitro loss-of-function and gain-of-function studies showed that Tcf21 inhibits the adipogenic differentiation of VAT progenitor cells. Bulk RNAseq and scRNAseq showed that Tcf21 lineage cells from Tcf21 knockout mice were developmentally in advance of those from their WT littermates. Mechanistic studies identified that Tcf21 inhibits adipogenesis through promoting the expression of Dlk1, a known negative regulator of adipogenesis, in the interstitial subpopulation of Tcf21 lineage cells.