MicroRNAs are small molecules, which work by suppressing the expression of specific sets of genes. They also control many biological processes.
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.