Irie Atsushi, Habuchi Hiroko, Kimata Koji, Sanai Yutaka
The Tokyo Metropolitan Institute of Medical Science, Department of Biochemical Cell Research, Bunkyo-ku, Tokyo 113-8613, Japan.
Biochem Biophys Res Commun. 2003 Sep 5;308(4):858-65. doi: 10.1016/s0006-291x(03)01500-6.
Although genetic studies have suggested that heparan sulfate (HS) is involved in bone morphogenetic protein (BMP)-mediated embryonic morphogenesis, it is unclear whether HS is directly involved in BMP-mediated signaling. Here, we investigate the involvement of HS in BMP-7 signaling. We show that HS and heparin chains specifically bind to BMP-7. Digestion of cell-surface HS with heparitinase interferes with BMP-7-mediated Smad phosphorylation in ROS 17/2.8 osteoblastic cells. Inhibiting sulfation of cell-surface HS with chlorate also causes interruption of Smad phosphorylation. Addition of exogenous heparin to ROS 17/2.8 cells prevents BMP-7-mediated Smad phosphorylation rather than enhances the BMP-7 signal, suggesting that HS should be anchored on the plasma membrane for BMP signaling. Moreover, BMP-7 binding to ROS 17/2.8 cells is inhibited by chlorate treatment and exogenous application of heparin. These results demonstrate that BMP-7 specifically binds to cell-surface HS and the BMP-7-HS interaction is required for BMP-7 signaling.
尽管基因研究表明硫酸乙酰肝素（HS）参与骨形态发生蛋白（BMP）介导的胚胎形态发生，但尚不清楚HS是否直接参与BMP介导的信号传导。在此，我们研究HS在BMP-7信号传导中的作用。我们发现HS和肝素链特异性结合BMP-7。用硫酸乙酰肝素酶消化细胞表面的HS会干扰ROS 17/2.8成骨细胞中BMP-7介导的Smad磷酸化。用氯酸盐抑制细胞表面HS的硫酸化也会导致Smad磷酸化中断。向ROS 17/2.8细胞中添加外源性肝素会阻止BMP-7介导的Smad磷酸化，而不是增强BMP-7信号，这表明HS应锚定在质膜上以进行BMP信号传导。此外，氯酸盐处理和外源性肝素的应用会抑制BMP-7与ROS 17/2.8细胞的结合。这些结果表明，BMP-7特异性结合细胞表面的HS，并且BMP-7-HS相互作用是BMP-7信号传导所必需的。
