Human primary brown and white fat cell secretome

Secreted proteins from adipose tissue play a role in metabolic cross-talk and homeostasis. We performed high sensitivity mass spectrometry-based proteomics on the cell media of human adipocytes derived from the supraclavicular brown adipose and from the subcutaneous white adipose depots of adult humans. We identified 471 potentially secreted proteins covering interesting protein categories such as hormones, growth factors, extracellular matrix proteins and proteins of the complement system, which were differentially regulated in brown and white adipocytes. A total of 101 proteins were exclusively quantified in brown adipocytes and among these were ependymin-related protein 1 (EPDR1). Functional studies suggested a role for EPDR1 in thermogenic adipogenesis. In conclusion, we report substantial differences between the secretomes of brown and white human adipocytes and identify novel candidate batokines that can be important regulators of metabolism.