HNRNPA2B1 regulates alternative RNA processing in the nervous system and accumulates in granules in ALS IPSC-derived motor neurons [hnRNPA2B1_Arrays_human_Fibs_1]. Homo sapiens

HnRNPA2B1 encodes an RNA binding protein associated with neurodegenerative disorders. However, its function in the nervous system is unclear. Transcriptome-wide cross-linking and immunoprecipitation in mouse spinal cord discover UAGG motifs enriched within ~2,500 hnRNP A2/B1 binding sites and an unexpected role for hnRNP A2/B1 in alternative polyadenylation. Loss of hnRNP A2/B1 results in alternative splicing, including skipping of an exon in amyotrophic lateral sclerosis (ALS)-associated D-amino acid oxidase (DAO) that reduces D-serine metabolism. Inclusion of the DAO exon is also reduced in transgenic ALS mice models. ALS-associated hnRNP A2/B1 D290V mutant patient fibroblasts and motor neurons differentiated from induced pluripotent stem cells demonstrate gain-of-mutant-dependent splicing differences. Mutant motor neurons also exhibit increased hnRNP A2/B1 localization to cytoplasmic granules during stress, which are abrogated by a small molecule CA43. Our findings and cellular resource identify RNA networks affected in loss of normal and mutated hnRNP A2/B1 with broad relevance to neurodegeneration. Overall design: Microarray in human primary fibroblasts treated with ASO to deplete hnRNP A2/B1 and controls. Three replicates per condition.

异质性核核糖核蛋白A2/B1（hnRNPA2B1）编码一种与神经退行性疾病相关的RNA结合蛋白，但其在神经系统中的具体功能尚未明确。本研究通过对小鼠脊髓开展全转录组交联免疫沉淀分析，发现约2500个hnRNP A2/B1结合位点中富集了UAGG基序，同时揭示了hnRNP A2/B1在可变多聚腺苷酸化中此前未被报道的作用。敲低hnRNP A2/B1会引发可变剪接异常，其中包括肌萎缩侧索硬化症（ALS）相关的D-氨基酸氧化酶（DAO）基因外显子跳跃，该异常会降低D-丝氨酸的代谢水平。在转基因ALS小鼠模型中，DAO基因外显子的包含率同样出现下降。携带ALS相关hnRNP A2/B1 D290V突变的患者成纤维细胞，以及由诱导多能干细胞分化得到的运动神经元，均表现出由突变介导的剪接功能获得性差异。应激状态下，突变型运动神经元中hnRNP A2/B1向细胞质颗粒的定位显著增强，而小分子化合物CA43可阻断这一异常过程。本研究的发现与细胞资源，明确了正常及突变型hnRNP A2/B1缺失所影响的RNA调控网络，该网络与神经退行性疾病具有广泛关联。实验整体设计：对使用反义寡核苷酸（ASO）敲低hnRNP A2/B1的人原代成纤维细胞及对照细胞进行微阵列分析，每组设置3次生物学重复。