Nakazato Ryota, Takarada Takeshi, Watanabe Takumi, Nguyen Binh Thanh, Ikeno Shinsuke, Hinoi Eiichi, Yoneda Yukio
Laboratory of Molecular Pharmacology, Division of Pharmaceutical Sciences, Kanazawa University Graduate School, Kanazawa, Ishikawa, Japan.
Laboratory of Molecular Pharmacology, Division of Pharmaceutical Sciences, Kanazawa University Graduate School, Kanazawa, Ishikawa, Japan.
Neurochem Int. 2014 Jul;74:24-35. doi: 10.1016/j.neuint.2014.04.010. Epub 2014 Apr 24.
Runt-related transcription factor-2 (Runx2) is the master regulator of osteoblastogenesis with an ability to promote differentiation of mesenchymal stem cells into the osteoblastic lineage. We have previously shown constitutive and functional expression of Runx2 by astroglial cells. In this study, we investigated the possible expression of Runx2 by both murine microglia and microglial cell line BV-2 cells. Runx2 expression was seen in cultured microglia and BV-2 cells, while sustained exposure to 1mM ATP led to a significant but transient increase in mRNA and corresponding protein expression of Runx2 within 24 h. The increase in Runx2 expression was invariably prevented by several chemicals with antagonistic properties for P2X7 purinergic receptor, calmodulin and calcineurin in BV-2 cells, with a P2X7 receptor agonist more than quadrupling Runx2 expression. A significant increase in Runx2 expression was seen in osteoclastic cells, but not in osteoblastic or chondrocytic cells, when exposed to a high concentration of ATP. In BV2-cells with control siRNA, a significant decrease was found in the number of cells with at least one process within 3 h after the exposure to 1mM ATP, followed by an increase up to 24 h. However, Runx2 siRNA significantly deteriorated the property to induce delayed process extension during 6-24 h after exposure to ATP along with drastically decreased Runx2 protein levels. These results suggest that Runx2 is constitutively and functionally expressed by microglial cells with responsiveness to ATP for upregulation in the murine brain.
runt相关转录因子2（Runx2）是成骨细胞生成的主要调节因子，具有促进间充质干细胞向成骨细胞谱系分化的能力。我们之前已经证明星形胶质细胞可组成性表达并具有功能活性的Runx2。在本研究中，我们调查了小鼠小胶质细胞和小胶质细胞系BV-2细胞中Runx2的可能表达情况。在培养的小胶质细胞和BV-2细胞中可观察到Runx2的表达，而持续暴露于1mM ATP会导致Runx2的mRNA和相应蛋白表达在24小时内显著但短暂增加。在BV-2细胞中，几种对P2X7嘌呤能受体、钙调蛋白和钙调神经磷酸酶具有拮抗特性的化学物质可始终阻止Runx2表达的增加，而一种P2X7受体激动剂可使Runx2表达增加四倍以上。当暴露于高浓度ATP时，破骨细胞中Runx2表达显著增加，而成骨细胞或软骨细胞中则未增加。在对照siRNA处理的BV2细胞中，暴露于1mM ATP后3小时内，至少有一个突起的细胞数量显著减少，随后在24小时内增加。然而，Runx2 siRNA显著恶化了暴露于ATP后6至24小时内诱导延迟突起延伸的特性，同时Runx2蛋白水平急剧下降。这些结果表明，小胶质细胞可组成性表达并具有功能活性的Runx2，且对ATP有反应，可在小鼠脑中上调表达。
