Lee Nayeon, Lee Sang Hwan, Lee Junghun, Lee Mi-Young, Lim Jaegook, Kim Subin, Kim Sunyoung
School of Biological Sciences, Seoul National University, Seoul, 08826, South Korea.
Division of Gene Therapy, Helixmith Co Ltd, Seoul, 07794, South Korea.
Biochem Biophys Rep. 2021 Mar 3;26:100973. doi: 10.1016/j.bbrep.2021.100973. eCollection 2021 Jul.
Hepatocyte growth factor (HGF) is a neurotrophic factor and its role in peripheral nerves has been relatively unknown. In this study, biological functions of HGF and its receptor c-met have been investigated in the context of regeneration of damaged peripheral nerves. Axotomy of the peripheral branch of sensory neurons from embryonic dorsal root ganglia (DRG) resulted in the increased protein levels of HGF and phosphorylated c-met. When the neuronal cultures were treated with a pharmacological inhibitor of c-met, PHA665752, the length of axotomy-induced outgrowth of neurite was significantly reduced. On the other hand, the addition of recombinant HGF proteins to the neuronal culture facilitated axon outgrowth. In the nerve crush mouse model, the protein level of HGF was increased around the injury site by almost 5.5-fold at 24 h post injury compared to control mice and was maintained at elevated levels for another 6 days. The amount of phosphorylated c-met receptor in sciatic nerve was also observed to be higher than control mice. When PHA665752 was locally applied to the injury site of sciatic nerve, axon outgrowth and injury mediated induction of cJun protein were effectively inhibited, indicating the functional involvement of HGF/c-met pathway in the nerve regeneration process. When extra HGF was exogenously provided by intramuscular injection of plasmid DNA expressing HGF, axon outgrowth from damaged sciatic nerve and cJun expression level were enhanced. Taken together, these results suggested that HGF/c-met pathway plays important roles in axon outgrowth by directly interacting with sensory neurons and thus HGF might be a useful tool for developing therapeutics for peripheral neuropathy.
肝细胞生长因子（HGF）是一种神经营养因子，其在周围神经中的作用相对尚不明确。在本研究中，已在受损周围神经再生的背景下研究了HGF及其受体c-met的生物学功能。来自胚胎背根神经节（DRG）的感觉神经元外周分支的轴突切断术导致HGF和磷酸化c-met的蛋白水平升高。当用c-met的药理学抑制剂PHA665752处理神经元培养物时，轴突切断术诱导的神经突生长长度显著缩短。另一方面，向神经元培养物中添加重组HGF蛋白促进了轴突生长。在神经挤压小鼠模型中，与对照小鼠相比，损伤后24小时损伤部位周围的HGF蛋白水平增加了近5.5倍，并在另外6天内维持在升高水平。还观察到坐骨神经中磷酸化c-met受体的量高于对照小鼠。当将PHA665752局部应用于坐骨神经损伤部位时，轴突生长和损伤介导的cJun蛋白诱导被有效抑制，表明HGF/c-met途径在神经再生过程中具有功能作用。当通过肌肉注射表达HGF的质粒DNA外源性提供额外的HGF时，受损坐骨神经的轴突生长和cJun表达水平增强。综上所述，这些结果表明HGF/c-met途径通过与感觉神经元直接相互作用在轴突生长中起重要作用，因此HGF可能是开发周围神经病变治疗方法的有用工具。
