Deconstructing cold-induced brown adipocyte neogenesis in mice [bulk RNA-seq]

Cold-exposure triggers neogenesis in classic interscapular brown adipose tissue (BAT) that involves activation of b1-adrenergic receptors, proliferation of PDGFRA+ adipose tissue stromal cells (ASCs), and recruitment of immune cells whose phenotypes are presently unknown. Single-cell RNA-sequencing (scRNA-seq) identified three ASC subpopulations that occupied distinct tissue locations. Of these, interstitial ASC1 were found to be direct precursors of new brown adipocytes (BA). Surprisingly, knockout of b1-adrenergic receptors in ASCs did not prevent cold-induced neogenesis, whereas pharmacological activation of the b3-adrenergic receptor on BAs was sufficient, suggesting that signals derived from mature BAs indirectly trigger ASC proliferation and differentiation. In this regard, cold exposure induced the delayed appearance of multiple macrophage and dendritic cell populations whose recruitment strongly correlated with the onset and magnitude of neogenesis across diverse experimental conditions. High resolution immunofluorescence and single molecule fluorescence in situ hybridization demonstrated that cold-induced neogenesis involves dynamic interactions between ASC1 and recruited immune cells that occur on the micrometer scale in distinct tissue regions. Our results indicate that neogenesis is not a reflexive response of progenitors to b-adrenergic signaling, but rather is a complex adaptive response to elevated metabolic demands within brown adipocytes. Whole-tissue RNA-sequencing of mouse interscapular brown adipose tissue (iBAT) after a cold-exposure time course. Data includes iBAT RNA-seq from mice housed at room temperature, or six cold-exposure time points: 6 hours, 1 day, 2 days, 3 days, 4 days, and 5 days. Cold exposure corresponds to housing at 6 degrees Celsius. Five mice were collected for each time point, totaling 35 RNA-seq libraries.