Description
Murine Runx3 is expressed in developing bone osteoblasts (OBLs) and its deletion in these cells culminates in severe congenital osteopenia. We demonstrate that Runx3 is non-redundantly involved in the proliferation of early pre-committed OBL progenitor cells, a critical step in the generation of adequate numbers of bone-forming OBLs. Thus, in the absence of Runx3 in cells of this lineage, the number of mature/active OBLs is significantly diminished, providing a mechanistic explanation to the observed osteopenia.