Separation of newly formed bone from older compact bone reveals clear compositional differences in bone matrix.
Separation of newly formed bone from older compact bone reveals clear compositional differences in bone matrix.
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新形成的骨与较旧的致密骨的分离揭示了骨基质的明显成分差异。
DOI：
10.1016/j.bone.2011.09.039
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发表时间：
2011
期刊：
影响因子：
4.1
通讯作者：
Gorski,JeffreyP
中科院分区：
文献类型：
--
作者：
Midura,RonaldJ;Midura,SharonB;Su,Xiaowei;Gorski,JeffreyP
在长骨骨干中，编织骨首先形成，然后转变为更矿化的致密骨组织。先前的证据表明，编织骨的非胶原蛋白组成可能与更成熟的骨组织不同，特别是在不同的磷酸化细胞外基质蛋白组方面。为了严格验证这一假设，我们开发了一种原位方法来分离同一长骨内新形成的骨和更成熟的骨，并将这种解剖方法与Western blotting相结合，对骨生理学和生物矿化重要的7种磷酸化基质蛋白进行相对比较。有趣的是，与更成熟的皮质骨相反，初级骨中富含75kDa的骨粘液蛋白（BSP）、63kDa的骨桥蛋白和75kDa形式的骨酸性糖蛋白-75 (BAG-75)，而骨连接素、胎蛋白A、基质细胞外磷酸糖蛋白（MEPE）和牙本质基质蛋白-1 （DMP-1）似乎均匀分布在这两个骨组织间室中。分析还显示，较大形式的骨桥蛋白（以及较小程度的BSP）主要存在于新形成的骨中，而较大形式的BAG-75主要存在于更成熟的皮质骨中。在新形成的和更成熟的骨组织提取物中都检测到较小尺寸的DMP-1和BAG-75，它们可能是体内蛋白水解加工的结果。完整的DMP-1 （97kDa）仅在未矿化的基质提取物中检测到。这些发现表明，即使在同一根长骨内，新形成的骨也表现出与更成熟的致密骨不同的非胶原基质蛋白组成，并表明个体非胶原蛋白的时间命运在生长的骨中是可变的。
In long bone diaphyses, woven bone forms first and then transitions into a more mineralized compact bone tissue. Prior evidence suggests that the non-collagenous protein composition of woven bone may be distinct from that of more mature bone tissue, particularly with respect to a diverse group of phosphorylated, extracellular matrix proteins. To critically test this hypothesis, we developed an in situ approach to isolate newly formed bone from more mature bone within the same long bone, and combine this anatomical approach with Western blotting to make relative comparisons of 7 phosphorylated matrix proteins important for bone physiology and biomineralization. Interestingly, 75kDa bone sialoprotein (BSP), 63kDa osteopontin, and the 75kDa form of bone acidic glycoprotein-75 (BAG-75) were enriched in primary bone as opposed to more mature cortical bone, while osteonectin, fetuin A, matrix extracellular phosphoglycoprotein (MEPE) and dentin matrix protein-1 (DMP-1) appeared to be equally distributed between these two bone tissue compartments. Analyses also revealed the presence of larger sized forms of osteopontin (and to a lesser degree BSP) mostly in newly formed bone, while larger forms of BAG-75 were mostly detected in more mature cortical bone. Smaller sized forms of DMP-1 and BAG-75 were detected in both newly formed and more mature bone tissue extracts, and they are likely the result of proteolytic processing in vivo. Intact DMP-1 (97kDa) was only detected in unmineralized matrix extracts. These findings indicate that newly formed bone exhibits a non-collagenous matrix protein composition distinct from that of more mature compact bone even within the same long bone, and suggest that the temporal fate of individual non-collagenous proteins is variable in growing bone.