Amelioration of spinal cord injury by the regulation of neurotmphin receptor p75-mediated signaling

1.脊髓损伤后基因表达变化的分析应用DNA芯片技术分析脊髓损伤后基因表达的变化。包括炎性细胞因子或淋巴因子在内的46个基因表达上调，涉及离子转运体或氨基酸转运体的18个基因表达下调。2抑制p75NTR诱导的负性信号的多肽。a)抑制RhoGDI与p75结合的多肽；b)抑制Sortilin与前脑源性神经营养因子(BDNF)结合的多肽，检测它们在脊髓损伤后的运动活性。然而，两种多肽均不能提高运动活性。脊髓损伤部位诱导的多种蛋白水解酶可能参与了多肽的降解。3 p75NTR基因修饰…对脊髓损伤的改善作用比较p75NTR基因敲除小鼠(KO小鼠)和野鼠脊髓损伤后运动能力的改善情况。KO小鼠在前8天的活动评分高于野鼠，但此后差异消失，表明p75NTR信号干扰了损伤早期的恢复。4条件性p75NTR转基因(TG)小鼠的建立构建了含有loxP基因和下游p75NTR基因终止密码子的载体DNA，并将其转移到受精卵中。由于引入的p75NTR基因只要不缺失loxP之间的终止密码子就不表达，因此动物的维护很容易。如果将区域特异性表达cre酶基因的转基因小鼠与p75NTR转基因小鼠杂交，p75NTR基因将同时在cre酶表达区域表达。该转基因动物将成为未来研究p75NTR功能的有用工具。较少

1. Analysis of alteration of gene expression after spinal cord injuryGenes of which expression were altered in the injured spinal cord were analyzed by the DNA array method. The 46 genes including inflammatory cytokines or lymphokines were upregulated and 18 genes involving ion transporter or amino acid transporter were downregulated. We focused on and analyzed some genes related to p75NTR signaling.2 Evaluation of the peptides that suppress the p75NTR-induced negative signals.a) A peptide expected to inhibit the binding between RhoGDI and p75, and b) the peptide expected to inhibit the binding between sortilin and pro-brain-derived neurotrophic factor (BDNF) were examined their activities on the locomotion activity after spinal cord injury. However, both peptides failed to improve the locomotion activity. Various proteases induced in the injury site of the spinal cord may be responsible for the degradation of the peptides.3 Amelioration of the spinal cord injury in p75NTR gene-modifie … More d animalsThe improvement of locomotion activity after spinal cord injury was compared between p75NTR gene-disrupted mouse (KO mouse) and wild mouse. KO mouse gave higher scores of the locomotion activity than wild mouse for the first 8 days, but the difference was disappeared thereinafter, suggesting that p75NTR signal disturbs the restoration at early stages of the damage.4 Development of the conditional p75NTR transgenic (Tg) mouseThe vector DNA containing a stop codon between loxp genes and the p75NTR gene in the down stream was constructed, and transferred to fertilized eggs. Because the introduced p75NTR gene does not express as long as stop codon between loxp is not deleted, the maintenance of the animal is easy. If the transgenic mice expressing cre enzyme gene in a region-specicic manner were hybridized with this p75NTR Tg mouse, the p75NTR gene would express simultaneously in the cre enzyme expressing regions. This Tg animals would become useful tool to investigate p75NTR function in the future. Less