Department of Physical Medicine and Rehabilitation, Rehabilitation Medicine Research Center, Rochester, Minnesota, USA.
Department of Physiology and Biomedical Engineering, Mayo Clinic Graduate School of Biomedical Sciences, Rochester, Minnesota, USA.
Glia. 2021 Sep;69(9):2111-2132. doi: 10.1002/glia.24012. Epub 2021 Apr 22.
Excessive activation of the thrombin receptor, protease activated receptor 1 (PAR1) is implicated in diverse neuropathologies from neurodegenerative conditions to neurotrauma. PAR1 knockout mice show improved outcomes after experimental spinal cord injury (SCI), however information regarding the underpinning cellular and molecular mechanisms is lacking. Here we demonstrate that genetic blockade of PAR1 in female mice results in improvements in sensorimotor co-ordination after thoracic spinal cord lateral compression injury. We document improved neuron preservation with increases in Synapsin-1 presynaptic proteins and GAP43, a growth cone marker, after a 30 days recovery period. These improvements were coupled to signs of enhanced myelin resiliency and repair, including increases in the number of mature oligodendrocytes, their progenitors and the abundance of myelin basic protein. These significant increases in substrates for neural recovery were accompanied by reduced astrocyte (Serp1) and microglial/monocyte (CD68 and iNOS) pro-inflammatory markers, with coordinate increases in astrocyte (S100A10 and Emp1) and microglial (Arg1) markers reflective of pro-repair activities. Complementary astrocyte-neuron co-culture bioassays suggest astrocytes with PAR1 loss-of-function promote both neuron survival and neurite outgrowth. Additionally, the pro-neurite outgrowth effects of switching off astrocyte PAR1 were blocked by inhibiting TrkB, the high affinity receptor for brain derived neurotrophic factor. Altogether, these studies demonstrate unique modulatory roles for PAR1 in regulating glial-neuron interactions, including the capacity for neurotrophic factor signaling, and underscore its position at neurobiological intersections critical for the response of the CNS to injury and the capacity for regenerative repair and restoration of function.
过度激活凝血酶受体,蛋白酶激活受体 1(PAR1)与从神经退行性疾病到神经创伤的多种神经病理学有关。PAR1 基因敲除小鼠在实验性脊髓损伤(SCI)后表现出更好的结果,但是关于潜在的细胞和分子机制的信息却很少。在这里,我们证明在雌性小鼠中基因阻断 PAR1 可导致胸段脊髓侧方压迫损伤后感觉运动协调性的改善。我们记录到突触素-1 突触前蛋白和生长锥标志物 GAP43 的增加,神经元保存得到改善,在 30 天的恢复期间。这些改善与增强的髓鞘弹性和修复的迹象有关,包括成熟少突胶质细胞数量的增加,它们的祖细胞和髓鞘碱性蛋白的丰度增加。这些对神经恢复底物的显著增加伴随着星形胶质细胞(Serp1)和小胶质细胞/单核细胞(CD68 和 iNOS)促炎标志物的减少,同时伴随着星形胶质细胞(S100A10 和 Emp1)和小胶质细胞(Arg1)标志物的协调增加,反映了促修复活动。补充的星形胶质细胞-神经元共培养生物测定表明,具有 PAR1 功能丧失的星形胶质细胞可促进神经元的存活和突起的生长。此外,通过抑制脑源性神经营养因子的高亲和力受体 TrkB,阻断星形胶质细胞 PAR1 失活对突起生长的促进作用。总之,这些研究表明 PAR1 在调节胶质细胞-神经元相互作用方面具有独特的调节作用,包括神经营养因子信号转导的能力,并强调其在神经生物学交叉点的位置对于中枢神经系统对损伤的反应以及再生修复和功能恢复的能力至关重要。