Teng Shavonne, Palmieri Alicia, Maita Isabella, Zheng Cynthia, Das Gitanjali, Park Juyeon, Zhou Renping, Alder Janet, Thakker-Varia Smita
a Department of Neuroscience and Cell Biology, Rutgers Robert Wood Johnson Medical School , Piscataway , New Jersey , USA.
b Department of Chemical Biology, Ernest Mario School of Pharmacy, Rutgers University , Piscataway , New Jersey , USA.
Brain Inj. 2019;33(10):1385-1401. doi: 10.1080/02699052.2019.1641622. Epub 2019 Jul 18.
Eph/Ephrin signaling is inhibitory for developing axons and blocking Eph pathways enhances regeneration after spinal cord injury. It was hypothesized that inhibition of Eph signaling promotes cellular and behavioral recovery after traumatic brain injury (TBI). Lateral fluid percussion (LFP) injury was performed on wildtype (WT) and EphA6 knockout (KO) mice. EphA6-Fc, Ephrin-A5-Fc fusion proteins, and sodium orthovanadate were used to alter the signaling pathway. Immunohistochemistry and tissue explants revealed cellular changes. Rotarod tests demonstrated vestibulomotor function. The EphA6 receptor expression is upregulated following LFP. Uninjured EphA6 KO mice exhibit greater neurite density and clustered Ephrin-A5-Fc causes growth cone collapse in vitro. After LFP, EphA6 KO mice demonstrate longer neurites and decreased neuronal cell death and astrocytosis compared to WT mice. Blocking EphA signaling by soluble EphA6-Fc fusion protein reduces cell death and improves motor function following LFP whereas clustered Ephrin-A5-Fc exacerbates cell death and neurodegeneration. Sodium orthovanadate rescues growth cone collapse in vitro as well as cell death and neurodegeneration in vivo. Eph/Ephrin signaling plays an inhibitory role following TBI. Targeting the Eph signaling pathway with Fc fusion proteins and pharmacological agents can be a novel strategy to counter the damaging effects of TBI. LFP: lateral fluid percussion; TBI: traumatic brain injury; KO: knockout; WT: wildtype; PTP2: protein phosphotyrosine phosphatase 2; Tg: transgenic; YFP: yellow fluorescent protein; ATM: atmospheres; RT-qPCR: Real-time-quantitative PCR; dpi: days post injury; GAPDH: glyceraldehyde-3-phosphate dehydrogenase; DAPI: 4',6-diamidino-2-phenylindole; PBS: phosphate buffered saline; GFAP: glial fibrillary acidic protein; FLJC: fluorojade C; CA: cornu ammonis; SEM: standard error of the mean; ANOVA: analysis of variance; PLSD: posthoc least significant difference.
Eph/Ephrin信号传导对发育中的轴突具有抑制作用，阻断Eph通路可增强脊髓损伤后的再生能力。据推测，抑制Eph信号传导可促进创伤性脑损伤（TBI）后的细胞和行为恢复。对野生型（WT）和EphA6基因敲除（KO）小鼠进行了侧方液压冲击（LFP）损伤。使用EphA6-Fc、Ephrin-A5-Fc融合蛋白和原钒酸钠来改变信号通路。免疫组织化学和组织外植体显示了细胞变化。转棒试验证明了前庭运动功能。LFP后EphA6受体表达上调。未受伤的EphA6 KO小鼠表现出更高的神经突密度，且聚集的Ephrin-A5-Fc在体外可导致生长锥塌陷。LFP后，与WT小鼠相比，EphA6 KO小鼠的神经突更长，神经元细胞死亡和星形细胞增生减少。可溶性EphA6-Fc融合蛋白阻断EphA信号传导可减少LFP后的细胞死亡并改善运动功能，而聚集的Ephrin-A5-Fc则会加剧细胞死亡和神经退行性变。原钒酸钠可挽救体外生长锥塌陷以及体内细胞死亡和神经退行性变。Eph/Ephrin信号传导在TBI后起抑制作用。用Fc融合蛋白和药物靶向Eph信号通路可能是对抗TBI损伤作用的一种新策略。LFP：侧方液压冲击；TBI：创伤性脑损伤；KO：基因敲除；WT：野生型；PTP2：蛋白酪氨酸磷酸酶2；Tg：转基因；YFP：黄色荧光蛋白；ATM：大气压；RT-qPCR：实时定量PCR；dpi：损伤后天数；GAPDH：甘油醛-3-磷酸脱氢酶；DAPI：4',6-二脒基-2-苯基吲哚；PBS：磷酸盐缓冲盐水；GFAP：胶质纤维酸性蛋白；FLJC：荧光玉髓C；CA：海马；SEM：均值标准误差；ANOVA：方差分析；PLSD：事后最小显著差异
