Department of Biology, University of Pennsylvania, Philadelphia, PA 19104.
Department of Genetics, Stanford University School of Medicine, Stanford, CA 94305.
J Immunol. 2018 Jul 1;201(1):157-166. doi: 10.4049/jimmunol.1701501. Epub 2018 May 14.
Human Ag R (HuR) is an RNA binding protein in the ELAVL protein family. To study the neuron-specific function of HuR, we generated inducible, neuron-specific HuR-deficient mice of both sexes. After tamoxifen-induced deletion of HuR, these mice developed a phenotype consisting of poor balance, decreased movement, and decreased strength. They performed significantly worse on the rotarod test compared with littermate control mice, indicating coordination deficiency. Using the grip-strength test, it was also determined that the forelimbs of neuron-specific HuR-deficient mice were much weaker than littermate control mice. Immunostaining of the brain and cervical spinal cord showed that HuR-deficient neurons had increased levels of cleaved caspase-3, a hallmark of cell apoptosis. Caspase-3 cleavage was especially strong in pyramidal neurons and α motor neurons of HuR-deficient mice. Genome-wide microarray and real-time PCR analysis further indicated that HuR deficiency in neurons resulted in altered expression of genes in the brain involved in cell growth, including trichoplein keratin filament-binding protein, Cdkn2c, G-protein signaling modulator 2, immediate early response 2, superoxide dismutase 1, and Bcl2. The additional enriched Gene Ontology terms in the brain tissues of neuron-specific HuR-deficient mice were largely related to inflammation, including IFN-induced genes and complement components. Importantly, some of these HuR-regulated genes were also significantly altered in the brain and spinal cord of patients with amyotrophic lateral sclerosis. Additionally, neuronal HuR deficiency resulted in the redistribution of TDP43 to cytosolic granules, which has been linked to motor neuron disease. Taken together, we propose that this neuron-specific HuR-deficient mouse strain can potentially be used as a motor neuron disease model.
人 Ag R(HuR)是 ELAVL 蛋白家族中的一种 RNA 结合蛋白。为了研究 HuR 的神经元特异性功能,我们生成了诱导型、神经元特异性 HuR 缺失的雌雄小鼠。在他莫昔芬诱导 HuR 缺失后,这些小鼠表现出平衡不良、运动减少和力量下降的表型。与同窝对照小鼠相比,它们在转棒试验中表现明显较差,表明协调能力不足。使用握力试验也确定了神经元特异性 HuR 缺失小鼠的前肢比同窝对照小鼠弱得多。大脑和颈脊髓的免疫染色显示 HuR 缺失神经元中 cleaved caspase-3(细胞凋亡的标志)水平升高。HuR 缺失小鼠的锥体神经元和α运动神经元中 caspase-3 切割尤其强烈。全基因组微阵列和实时 PCR 分析进一步表明,神经元中的 HuR 缺失导致大脑中参与细胞生长的基因表达发生改变,包括 trichoplein 角蛋白丝结合蛋白、Cdkn2c、G 蛋白信号调节因子 2、即刻早期反应 2、超氧化物歧化酶 1 和 Bcl2。神经元特异性 HuR 缺失小鼠脑组织中另外富集的基因本体术语在很大程度上与炎症有关,包括 IFN 诱导基因和补体成分。重要的是,这些 HuR 调节基因中的一些在肌萎缩侧索硬化症患者的大脑和脊髓中也发生了显著改变。此外,神经元 HuR 缺失导致 TDP43 重新分布到细胞溶质颗粒中,这与运动神经元疾病有关。总之,我们提出这种神经元特异性 HuR 缺失小鼠品系可潜在地用作运动神经元疾病模型。