Merle Blandine, Bouet Guenaelle, Rousseau Jean-Charles, Bertholon Cindy, Garnero Patrick
INSERM Research Unit 1033, Université Lyon 1, Lyon, France.
Cell Biol Int. 2014 Mar;38(3):398-404. doi: 10.1002/cbin.10219. Epub 2013 Dec 31.
Periostin (Postn) and transforming growth factor β-induced protein (TGFβIp) are two closely related extracellular matrix (ECM) proteins predominantly distributed in collagen-rich connective tissues submitted to mechanical strain, including bone and more specifically the periosteum. We have investigated the expression of Postn and TGFβIp mRNA by primary osteoblasts isolated from mouse periosteum and calvaria, or by the osteoblast-like MC3T3-E1 cell line, and by osteoclasts from mouse long bones differentiated in vitro. Secretion of Postn was measured with a specific ELISA. Postn and TGFβIp mRNA were concomitantly expressed in all three osteoblast models all along the differentiation process in a time-dependent manner. Both Postn and TGFβIp transcripts appeared early in osteoblast differentiation, and their expression increased 3-10 times in mature osteoblast cells. Expression decreased after differentiation was achieved and when the cultures mineralised. ELISA for secreted Postn showed a similar pattern. When MC3T3-E1 cells were treated with TGF-β, Postn and TGFβIp mRNA expression and secretion were stimulated, whereas 1.25(OH)(2)D(3) had no detectable effect. Osteoclasts also expressed both Postn and TGFβIp during in vitro differentiation. Expression of both Postn and TGFβIp peaks in the early phases of osteoblast differentiation, and decreases later at the start of mineralisation. A novel finding is that Postn and TGFβIp are expressed by osteoclasts in vitro. Therefore Postn and TGFβIp proteins are potential biomarkers of early osteoblast differentiation and new bone formation.
骨膜蛋白（Postn）和转化生长因子β诱导蛋白（TGFβIp）是两种密切相关的细胞外基质（ECM）蛋白，主要分布在承受机械应变的富含胶原蛋白的结缔组织中，包括骨骼，更具体地说是骨膜。我们研究了从小鼠骨膜和颅骨分离的原代成骨细胞、成骨细胞样MC3T3-E1细胞系以及体外分化的小鼠长骨破骨细胞中Postn和TGFβIp mRNA的表达情况。用特异性酶联免疫吸附测定法（ELISA）检测Postn的分泌。在所有三种成骨细胞模型的整个分化过程中，Postn和TGFβIp mRNA均以时间依赖性方式同时表达。Postn和TGFβIp转录本在成骨细胞分化早期出现，在成熟成骨细胞中的表达增加3至10倍。分化完成后以及培养物矿化时，表达下降。分泌型Postn的ELISA显示出类似的模式。当用转化生长因子-β处理MC3T3-E1细胞时，Postn和TGFβIp mRNA的表达及分泌受到刺激，而1,25-二羟维生素D3没有可检测到的影响。破骨细胞在体外分化过程中也表达Postn和TGFβIp。Postn和TGFβIp在成骨细胞分化早期表达达到峰值，随后在矿化开始时下降。一个新发现是，Postn和TGFβIp在体外由破骨细胞表达。因此，Postn和TGFβIp蛋白是早期成骨细胞分化和新骨形成的潜在生物标志物。
