Delivering progranulin to neuronal lysosomes protects against excitotoxicity.
Delivering progranulin to neuronal lysosomes protects against excitotoxicity.
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将颗粒蛋白前体递送至神经元溶酶体保护免受兴奋性毒性。
DOI：
10.1016/j.jbc.2021.100993
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发表时间：
2021-09
期刊：
影响因子：
--
通讯作者：
Arrant AE
中科院分区：
文献类型：
--
作者：
Davis SE;Roth JR;Aljabi Q;Hakim AR;Savell KE;Day JJ;Arrant AE
前颗粒蛋白（GRN）的功能缺失突变是额颞叶痴呆（FTD）的主要遗传原因，可能是由于前颗粒蛋白的神经营养和抗炎作用的丧失。原颗粒蛋白促进神经元生长，防止兴奋性毒性和其他形式的损伤。目前尚不清楚这些神经营养效应是通过细胞信号传导还是通过促进溶酶体功能介导的。前颗粒蛋白是一种分泌性蛋白，可通过细胞表面受体激活神经营养信号。然而，前颗粒蛋白被有效地运输到溶酶体，是维持溶酶体功能所必需的。为了确定哪一种机制介导了前颗粒蛋白对兴奋性毒性的保护，我们生成了表达前颗粒蛋白（PGRN）或溶酶体靶向前颗粒蛋白（L-PGRN）的慢病毒载体。L-PGRN是通过将LAMP-1跨膜结构域和细胞质结构域融合到原粒蛋白的c端而产生的。L-PGRN没有可检测到的分泌，但被传递到溶酶体并加工成颗粒。PGRN和L-PGRN对大鼠皮层初级神经元的NMDA兴奋性毒性具有保护作用，但L-PGRN的保护作用比PGRN更一致。L-PGRN的保护作用可能是通过自噬-溶酶体途径介导的。在对照神经元中，兴奋性毒性剂量的NMDA刺激自噬，用3-甲基腺嘌呤抑制自噬可减少兴奋性毒性细胞死亡。L-PGRN减弱了NMDA的自噬反应，阻断了3-甲基腺苷的保护作用。这不是由于自噬的普遍损害，因为L-PGRN增加了基础自噬，而不改变营养饥饿后的自噬。这些数据表明，前颗粒蛋白对兴奋性毒性的保护不需要细胞外的前颗粒蛋白，而是通过溶酶体介导的，提供了前颗粒蛋白溶酶体和神经营养作用之间的机制联系。
Loss-of-function mutations in progranulin (GRN) are a major genetic cause of frontotemporal dementia (FTD), possibly due to loss of progranulin’s neurotrophic and anti-inflammatory effects. Progranulin promotes neuronal growth and protects against excitotoxicity and other forms of injury. It is unclear if these neurotrophic effects are mediated through cellular signaling or through promotion of lysosomal function. Progranulin is a secreted proprotein that may activate neurotrophic signaling through cell-surface receptors. However, progranulin is efficiently trafficked to lysosomes and is necessary for maintaining lysosomal function. To determine which of these mechanisms mediates progranulin’s protection against excitotoxicity, we generated lentiviral vectors expressing progranulin (PGRN) or lysosome-targeted progranulin (L-PGRN). L-PGRN was generated by fusing the LAMP-1 transmembrane and cytosolic domains to the C-terminus of progranulin. L-PGRN exhibited no detectable secretion, but was delivered to lysosomes and processed into granulins. PGRN and L-PGRN protected against NMDA excitotoxicity in rat primary cortical neurons, but L-PGRN had more consistent protective effects than PGRN. L-PGRN’s protective effects were likely mediated through the autophagy-lysosomal pathway. In control neurons, an excitotoxic dose of NMDA stimulated autophagy, and inhibiting autophagy with 3-methyladenine reduced excitotoxic cell death. L-PGRN blunted the autophagic response to NMDA and occluded the protective effect of 3-methyladenine. This was not due to a general impairment of autophagy, as L-PGRN increased basal autophagy and did not alter autophagy after nutrient starvation. These data show that progranulin’s protection against excitotoxicity does not require extracellular progranulin, but is mediated through lysosomes, providing a mechanistic link between progranulin’s lysosomal and neurotrophic effects.
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影响因子：
64.8
作者：
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通讯作者：
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