Department of Orthopaedic Surgery, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA.
Osteoporos Int. 2012 Apr;23(4):1399-413. doi: 10.1007/s00198-011-1728-5. Epub 2011 Sep 1.
We profiled the global gene expression of a bone marrow-derived mesenchymal pluripotent cell line in response to Runx2 expression. Besides osteoblast differentiation, Runx2 promoted the osteoclastogenesis of co-cultured splenocytes. This was attributable to the upregulation of many novel osteoclastogenic genes and the downregulation of anti-osteoclastogenic genes.
In addition to being a master regulator for osteoblast differentiation, Runx2 controls osteoblast-driven osteoclastogenesis. Previous studies profiling gene expression during osteoblast differentiation had limited focus on Runx2 or paid little attention to its role in mediating osteoblast-driven osteoclastogenesis.
ST2/Rx2(dox), a bone marrow-derived mesenchymal pluripotent cell line that expresses Runx2 in response to Doxycycline (Dox), was used to profile Runx2-induced gene expression changes. Runx2-induced osteoblast differentiation was assessed based on alkaline phosphatase staining and expression of classical marker genes. Osteoclastogenic potential was evaluated by TRAP staining of osteoclasts that differentiated from primary murine splenocytes co-cultured with the ST2/Rx2(dox) cells. The BeadChip™ platform (Illumina) was used to interrogate genome-wide expression changes in ST2/Rx2(dox) cultures after treatment with Dox or vehicle for 24 or 48 h. Expression of selected genes was also measured by RT-qPCR.
Dox-mediated Runx2 induction in ST2 cells stimulated their own differentiation along the osteoblast lineage and the differentiation of co-cultured splenocytes into osteoclasts. The latter was attributable to the stimulation of osteoclastogenic genes such as Sema7a, Ltc4s, Efnb1, Apcdd1, and Tnc as well as the inhibition of anti-osteoclastogenic genes such as Tnfrsf11b (OPG), Sema3a, Slco2b1, Ogn, Clec2d (Ocil), Il1rn, and Rspo2.
Direct control of osteoblast differentiation and concomitant indirect control of osteoclast differentiation, both through the activity of Runx2 in pre-osteoblasts, constitute a novel mechanism of coordination with a potential crucial role in coupling bone formation and resorption.
我们分析了骨髓间充质多能细胞系在响应 Runx2 表达时的全球基因表达。除了成骨细胞分化，Runx2 还促进了共培养脾细胞的破骨细胞形成。这归因于许多新的破骨细胞生成基因的上调和抗破骨细胞生成基因的下调。
Runx2 不仅是成骨细胞分化的主要调节因子，还控制着成骨细胞驱动的破骨细胞形成。以前研究成骨细胞分化过程中基因表达的 profiling 研究主要集中在 Runx2 上，或者很少关注它在介导成骨细胞驱动的破骨细胞形成中的作用。
ST2/Rx2(dox)，一种骨髓间充质多能细胞系，在 Doxycycline (Dox) 作用下表达 Runx2，用于分析 Runx2 诱导的基因表达变化。基于碱性磷酸酶染色和经典标记基因的表达来评估 Runx2 诱导的成骨细胞分化。通过共培养 ST2/Rx2(dox) 细胞与原代小鼠脾细胞分化的破骨细胞的 TRAP 染色来评估破骨细胞形成潜能。BeadChip™ 平台（Illumina）用于检测 Dox 或载体处理 24 或 48 小时后 ST2/Rx2(dox) 培养物的全基因组表达变化。还通过 RT-qPCR 测量选定基因的表达。
ST2 细胞中 Dox 介导的 Runx2 诱导刺激了它们自身沿着成骨细胞谱系的分化以及共培养脾细胞向破骨细胞的分化。后者归因于破骨细胞生成基因如 Sema7a、Ltc4s、Efnb1、Apcdd1 和 Tnc 的刺激以及抗破骨细胞生成基因如 Tnfrsf11b (OPG)、Sema3a、Slco2b1、Ogn、Clec2d (Ocil)、Il1rn 和 Rspo2 的抑制。
直接控制成骨细胞分化和通过前成骨细胞中 Runx2 的活性间接控制破骨细胞分化，构成了一种新的协调机制，在耦联骨形成和吸收中具有潜在的关键作用。
