A Classical Brown Adipose Tissue mRNA Signature Partly Overlaps with Brite in the Supraclavicular Region of Adult Humans

Human brown adipose tissue (BAT) has been detected in adults but was recently suggested to be of brite/beige origin. We collected BAT from the supraclavicular region in 21 patients undergoing surgery for suspected cancer in the neck area and assessed the gene expression of established murine markers for brown, brite/beige, and white adipocytes. We demonstrate that a classical brown expression signature, including upregulation of miR-206, miR-133b, LHX8, and ZIC1 and downregulation of HOXC8 and HOXC9, coexists with an upregulation of two newly established brite/beige markers, TBX1 and TMEM26. A similar mRNA expression profile was observed when comparing isolated human adipocytes from BAT and white adipose tissue (WAT) depots, differentiated in vitro. In conclusion, our data suggest that human BAT might consist of both classical brown and recruitable brite adipocytes, an observation important for future considerations on how to induce human BAT.