Many biological processes are controlled by small molecules known as microRNAs, which work by suppressing the expression of specific sets of genes. Xiang-Hang Luo and colleagues, at Second Xiangya Hospital of Central South University, People's Republic of China, have now identified a previously unknown microRNA (miR-2861) as crucial to bone maintenance in mice and humans.

Of clinical importance, expression of functional miR-2861 was absent in two related adolescents with primary osteoporosis.

Several lines of evidence determined the key role of miR-2861 in maintaining bone. First, miR-2861 promoted the in vitro development of a mouse stromal cell line into the cells responsible for bone formation. Second, in mice, in vivo silencing of miR-2861 inhibited bone formation and decreased bone mass. Last, analysis of ten patients with primary osteoporosis revealed two related adolescents in whom disease was caused by a mutation in the miR-2861 precursor (pre-miR-2861) that blocked expression of miR-2861.

These data led the authors to conclude that miR-2861 has an important role in controlling the generation of the cells responsible for bone formation and that defects in the processing of its precursor can cause osteoporosis.

The research appears in the Journal of Clinical Investigation.