A synthetic peptide fragment of human MEPE stimulates new bone formation in vitro and in vivo
A synthetic peptide fragment of human MEPE stimulates new bone formation in vitro and in vivo
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DOI：
10.1359/jbmr.0301263
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发表时间：
2004-03-01
影响因子：
6.2
通讯作者：
Yoneda, T
中科院分区：
文献类型：
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作者：
Hayashibara, T;Hiraga, T;Yoneda, T
基质细胞外磷酸糖蛋白（MEPE）被认为是磷酸尿激素phosphatonin的候选者。我们发现含有RGD和SGDG序列的MEPE的合成肽片段在体外和体内刺激新骨形成。基质细胞外磷酸糖蛋白（MEPE）最近被鉴定为磷酸尿激素磷酸化激素的候选者，磷酸化激素磷酸化激素与磷酸盐代谢紊乱、佝偻病、以及与X连锁低磷酸盐血症佝偻病（XLH）和致癌低磷酸盐血症骨软化症（OHO）相关的骨软化症。MEPE表达主要在成骨细胞中发现，并且MEPE同源物缺陷的小鼠显示骨密度增加，表明成骨细胞中产生的MEPE负调节骨形成。在这项研究中，我们研究了MEPE的合成23肽片段的作用，（AC-100，区域242-264），含有RGD（整合素结合）和SGDG（糖胺聚糖附着）基序在体外和体内对骨形成的影响。在新生小鼠颅骨的器官培养物中和通过将AC-100注射到小鼠颅骨上的体内检测AC-100的成骨活性。组织形态计量学检查显示，在器官培养中，AC-100刺激新生小鼠颅骨中成骨细胞数量增加的新骨形成。相比之下，没有RGD或SGDG基序的合成MEPE片段肽未能增加新骨形成。通过钙黄绿素双标记技术测定，在小鼠颅骨上每日重复皮下注射AC-100可增加骨厚度并刺激新骨形成。然而，其中的RGD或SGDG序列被打乱的肽在体内不刺激新骨形成。AC-100可促进人原代成骨细胞的增殖和碱性磷酸酶活性，并激活黏着斑激酶（FAK）和细胞外信号调节蛋白激酶（ERK）。结论：我们的结果表明，与人MEPE片段序列相对应的合成肽可刺激成骨细胞数量增加，促进新骨形成。结果还表明，RGD和SGDG基序对AC-100的成骨活性至关重要，可能是通过激活成骨细胞中的整合素信号通路：AC-100的合成代谢作用可能有利于与骨形成减少相关的骨疾病。
Matrix extracellular phosphoglycoprotein (MEPE) was proposed as a candidate for the phosphaturic hormone phosphatonin. We found that a synthetic peptide fragment of MEPE containing the RGD and SGDG sequence stimulated new bone formation in vitro and in vivo.Introduction: Matrix extracellular phosphoglycoprotein (MEPE) was recently identified as a candidate for the phosphaturic hormone phosphatonin, which has been implicated in disturbed phosphate metabolism, rickets, and osteomalacia associated with X-linked hypophosphatemic rickets (XLH) and oncogenic hypophosphatemic osteomalacia (OHO). MEPE expression was predominantly found in osteoblasts, and mice deficient in a homolog of MEPE showed increased bone density, suggesting, that MEPE produced in osteoblasts negatively regulates bone formation. In this study, we examined the effects of a synthetic 23mer peptide fragment of MEPE (AC-100, region 242-264) containing the RGD (integrin-binding) and SGDG (glycosaminoglycan-attachment) motif onbone formation in vitro and in vivo.Materials and Methods: The osteogenic activity of AC-100 was examined in organ cultures of neonatal mouse calvariae and in vivo by injecting AC-100 onto the calvariae of mice.Results: Histomorphometric examination showed that AC-100 stimulated new bone formation with increased numbers of osteoblasts in neonatal mouse calvariae in organ culture. In contrast, synthetic MEPE fragment peptides without either the RGD or SGDG motif failed to increase new bone formation. Repeated daily subcutaneous injections of AC-100 onto the calvariae in mice increased bone thickness and stimulated new bone formation as determined by the calcein doublelabeling technique. However, peptides in which the RGD or SGDG sequence was scrambled did not stimulate new bone formation in vivo. AC-100 increased cell proliferation and alkaline phosphatase activity and activated focal adhesion kinase (FAK) and extracellular signal-regulated protein kinase (ERK) in human primary osteoblasts.Conclusion: Our results show that a synthetic peptide corresponding with the sequence of human MEPE fragment stimulates new bone formation with increased number of osteoblasts. The results also suggest that the RGD and SGDG motifs are critical to the osteogenic activity of AC-100, presumably through activating integrin signaling pathways in osteoblasts: The anabolic effects of AC-100 may be beneficial for bone diseases associated with decreased bone formation.