OMgp LRR181-228:OMgp神经突起生长抑制功能的主要结构域

OMgp LRR181-228: The Predominant Domain of OMgp in Neurite Outgrowth Inhibition

OMgp(oligodendrocyte-myelinglycoprotein)可以通过与MAG、nogo-66等神经再生抑制因子竞争结合同一受体NgR而诱使生长锥溃变和抑制神经突起的生长。以前的研究表明,在OMgp与NgR结合抑制神经突起生长的过程中,OMgp的亮氨酸富含重复序列(LRR)是必需的。为进一步了解OMgpLRR在神经突起生长中的作用及其结构与功能之间的关系,采用PCR-定点突变法对OMgpLRR结构域分段删除,表达了删除不同基因片段后的OMgpLRR蛋白,通过对表达有NgR的CHO细胞(NgR-CHO)的黏附实验和对原代培养神经细胞的抑制实验对其功能进行了研究。结果显示,分别删除了OMgp25-56、57-133、134-180位氨基酸的OMgpLRR蛋白仍具有结合NgR-CHO和抑制原代培养的神经元突起生长的作用;而删除了第181-228位氨基酸的OMgpLRR蛋白则失去了对原代培养神经元的生长抑制作用,但仍然具有结合NgR的能力。表明OMgp181-228在OMgp的功能中具有重要的意义。删除了第181-228位氨基酸的OMgpLRR蛋白可望作为OMgp的竞争性抑制剂,用于中枢神经系统损伤后神经再生的治疗。

Several observations suggest that the leucine-rich repeats (LRR) domain of oligodendrocyte-myelin glycoprotein (OMgp) may play an important role in inhibition of neurite outgrowth and axonal regeneration after brain injury. To better understand structure-function relationships for the OMgp LRR domain and its effects in neurite regeneration, distinct OMgp leucine-rich repeat were deleted by PCR based site-directed mutagenesis. The gene deleted OMgp LRR fragments were expressed with GST protein and the expressed proteins were used to culture with NgR-expressing CHO and hippocampal neurons. Results show that the deletion of OMgp amino acid residues 25-56, 57-133,134-180 did not interrupt its effects in binding NgR-expressing CHO and inhibiting hippocampal neurons growth. But the fragment deleted amino acid residues 181-228 can only bind with NgR-expressing CHO and lost the effect of neurite outgrowth inhibition. Results suggest that the OMgp amino acid 181-228 is the predominant domain in neurite outgrowth inhibition of OMgp. The OMgp LRR fragment without amino acid residues 181-228 may be a potent reagent for encouraging regeneration in the adult central nervous system following injury.