OMgp不同结构域在抑制神经突起生长中的作用

Distinct Effects of OMgp Domains in Neurite Outgrowth Inhibition

OMgp(oligodendrocyte-myelin glycoprotein)是一种在中枢神经系统表达的GPI连接的糖蛋白。最新发现,它具有诱使生长锥溃变和抑制神经突起再生的作用,这一作用是通过与nogo-66等神经再生抑制因子竞争结合同一受体NgR而实现的。但其相互作用的确切部位尚不能肯定。利用GST融合蛋白表达系统,分段表达了含有不同OMgp结构域的片段,对其与NgR作用的结构域进行了研究。结果表明,在OMgp与NgR的黏附结合过程中,OMgp的亮氨酸富含重复序列结构域是必需的,只有含该结构域的OMgp蛋白片段才能黏附表达有NgR的CHO细胞,并抑制神经突起的生长;在体外,含有丝/苏氨酸富含重复序列结构域的OMgp蛋白片段虽然具有微弱的沉降NgR的功能,但并不能抑制神经突起的生长。该结果将有助于中枢神经系统损伤后神经再生的理论与治疗研究。

The oligodendrocyte-myelin glycoprotein (OMgp), a phosphatidylinositol-linked membrane glyco- protein expressed in the brain, was found to be an inhibitor of neurite outgrowth and axonal regeneration after brain injury. Several observation suggest that the LRR domain of OMgp may play an important role in inhibition of cell proliferation. Here we report an analysis of the domain requirement of OMgp in neurite outgrowth inhibition. The distinct domain of OMgp was subcloned into pGEX-4T vector and GST-fusion protein comprised distinct domain of OMgp were expressed. The protein were used to culture with NgR-expressing CHO and hippocampal neurons. Results show that the fragment consisting of the S/T domain and C-terminal of OMgp can not bind with NgR-expressing CHO cell. The fragment representing of LRR can bind with NgR-expressing CHO and inhibit the neurite outgrowth of primary neurons. It can also pull down NgR from mouse brain. The results suggest that the LRR domain of OMgp is required and sufficient for binding of NgR and neurite outgrowth inhibition.