Loss of Runx3 in osteoblasts provokes severe congenital osteopenia

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. This experiment was aimed at identifying genes that are likely regulated by Runx3 along osteoblastogenesis. To elucidate the Runx3-mediated transcriptional program along OBL differentiation, we compared gene expression profile in WT and Runx3f/f/Col1a1-cre calvarial OBLs. Progenitor cells were purified and RNA extracted, reverse-transcribed, fragmented, labeled and hybridized to GeneChip® Mouse Gene 2.0 ST Array.

小鼠Runx3在发育中的骨成骨细胞（osteoblasts，OBLs）中表达，在这类细胞中敲除Runx3会导致严重的先天性骨质减少症。本研究证实，Runx3在早期定型前成骨细胞祖细胞的增殖过程中发挥非冗余功能，而该增殖步骤是生成足量骨形成性成骨细胞的关键环节。因此，当该细胞谱系中缺乏Runx3时，成熟/活化成骨细胞的数量会显著减少，这为所观察到的骨质减少症提供了机制层面的解释。本实验旨在鉴定成骨过程中可能受Runx3调控的基因。为阐明Runx3介导的成骨细胞分化转录调控程序，本研究对比了野生型（Wild Type，WT）与Runx3f/f/Col1a1-cre颅盖骨成骨细胞的基因表达谱。实验中我们纯化了祖细胞，提取RNA并进行反转录、片段化、标记，随后将其与GeneChip®小鼠基因2.0 ST芯片进行杂交。