Genetic inhibition of CRMP2 phosphorylation at serine 522 promotes axonal regeneration after optic nerve injury
Genetic inhibition of CRMP2 phosphorylation at serine 522 promotes axonal regeneration after optic nerve injury
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DOI：
10.1038/s41598-019-43658-w
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发表时间：
2019-05-10
影响因子：
4.6
通讯作者：
Ohshima, Toshio
中科院分区：
文献类型：
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作者：
Kondo, Shunsuke;Takahashi, Kazuya;Ohshima, Toshio
轴突变性发生在各种神经系统疾病和创伤性神经损伤中，轴突再生受到中枢神经系统抑制因素的限制。细胞周期蛋白依赖性激酶 5 和糖原合酶激酶 3 beta (GSK3 beta) 由其中一种抑制剂激活，而塌陷素反应介导蛋白 2 (CRMP2) 则由这两种激酶磷酸化。我们之前开发了 CRMP2 敲入 (CRMP2 KI) 小鼠系，其中 CRMP2 在 Ser 522 处的磷酸化受到抑制。由于CRMP2 KI小鼠在脊髓损伤后表现出促进轴突再生，我们假设CRMP2 KI小鼠在视神经损伤后会表现出更高的轴突再生。在这项研究中，我们首先表明，CRMP2 KI 小鼠视神经挤压 (ONC) 损伤后微管的解聚受到抑制。 ONC 后视网膜神经节细胞的损失也减少了。我们发现 ONC 后 4 周，CRMP2KI 的视神经中 GAP43（再生轴突标记物）的蛋白水平高于野生型的蛋白水平。我们进一步观察到 CRMP2 KI 小鼠 ONC 后视神经中示踪剂标记的轴突数量增加。这些结果表明，抑制 CRMP2 磷酸化可抑制视神经损伤后轴突变性并促进轴突再生。
Axonal degeneration occurs in various neurological diseases and traumatic nerve injury, and axonal regeneration is restricted by inhibitory factors in the central nervous system. Cyclin-dependent kinase 5 and glycogen synthase kinase 3 beta(GSK3 beta) are activated by one of those inhibitors, and collapsin response mediator protein 2 (CRMP2) is phosphorylated by both kinases. We previously developed a CRMP2 knock-in (CRMP2 KI) mouse line, in which CRMP2 phosphorylation at Ser 522 is inhibited. Because CRMP2 KI mice showed promotion of axonal regeneration after spinal cord injury, we hypothesized that CRMP2 KI mice would show higher axonal regeneration after optic nerve injury. In this study, we first show that depolymerization of microtubules after optic nerve crush (ONC) injury was suppressed in CRMP2 KI mice. Loss of retinal ganglia cells was also reduced after ONC. We found that protein level of GAP43, a marker of regenerative axons, was higher in the optic nerve from CRMP2KI than that from wild type 4 weeks after of ONC. We further observed increased numbers of axons labeled by tracer in the optic nerve after ONC in CRMP2 KI mice. These results suggest that inhibition of phosphorylation of CRMP2 suppresses axonal degeneration and promotes axonal regeneration after optic nerve injury.