A critical relationship between bone and fat: the role of bone marrow adipose-derived RANKL in bone metabolism.

Recent studies have unveiled unique functions of the bone marrow adipose tissue (BMAT), which represent over 10% of the total adipose tissue mass in healthy adults. Increasing evidence is emerging as to how BMAT deposition and osteoporosis are linked under normal and pathophysiological conditions, which is opening up novel treatment avenues. However, the means by which bone marrow adipocytes (BMAs) regulate bone remodeling and their involvement in osteoporosis remained unknown. A study in this issue of EMBO Reports (Hu et al, 2021) and a study in Journal of Clinical Investigation (Yu et al, 2021) reports independently that BMA-derived RANKL regulates osteoclastogenesis and bone remodeling, indicating that excessive RANKL generated by BMAs is an underlying cause for osteoporosis.