CHARACTERIZATION OF THE BONE FORMING FACTORS IN SERUM

骨形态发生蛋白（BMPs）是骨形成的重要调节因子，能诱导间充质细胞向成骨细胞分化。BMP-2在1小时内在细胞中诱导Idlan抑制剂的转录用于肌生成。在人Idl基因的-985 bp和-957 bp之间的富含GC的区域被鉴定为BMP响应元件。BRE上的BMP-2诱导了一种独特的DNA-蛋白质复合物。BMP-2诱导的复合物含有Smad 1和Smad 4，可能是两种Smads的复合物。BMP活性受靶细胞外部和内部的许多分子调节。我们研究了肝素对BMP诱导的C2 C12成肌细胞成骨细胞分化的影响。用肝素处理剂量依赖性地增强由100 ng/ml BMP-2诱导的ALP活性。然而，化学修饰的肝素衍生物已经失去了这种刺激能力。肝素不增加BMP-受体复合物的量。我们使用报告构建体监测BMP应答细胞，其中不稳定的增强型绿色荧光蛋白在Idl启动子中的BMP应答元件的控制下驱动。肝素治疗增加了一些EGFP表达细胞在30小时。保护骨形成蛋白对积累到细胞层中可能发挥重要作用，肝素的刺激活性。这些结果表明，多糖，如肝素和硫酸乙酰肝素，参与全身和/或局部调节骨形成。

Bone morphogenetic proteins (BMPs), which can induce osteoblast differentiation in mesenchymal cells, are important regulators for bone formation. BMP-2 induces transcription of Idlan inhibitor for myogenesis, within 1 h in the cells. A GC-rich region between -985 bp and -957 bp of the human Idl gene was identified as a BMP-responsive element. A unique DNA-protein complex was induced in response to BMP-2 on the BRE. The complex induced by BMP-2 contained Smadl and Smad4, possibly as a complex of both Smads. BMP activity is regulated by a number of molecules at the outside and the inside of the target cells. We examined the effects of heparin on the BMP-induced osteoblast differentiation in C2C12 myoblasts. Treating with heparin dose- dependently enhanced the ALP activity induced by 100 ng/ml of BMP-2. However, chemically desulfated heparin-derivatives have lost this stimulatory capacity. The amount of BMP-receptor complex was not increased by heparin. We monitored the BMP-responding cells using a reporter construct in which the destabilized enhanced green fluorescent protein was driven under the control of the BMP-responsive element in the Idl promoter. Heparin-treatment increased a number of the EGFP-expressing cells at 30 h.Protection of BMPs against accumulation into the cell layer may play an important role in the stimulatory activity of heparin. These results suggest that polysaccharides, such as heparin and heparan sulfate, are involved in systemic and/or local regulation of bone formation.