These authors contributed equally to this work.
Hum Mol Genet. 2013 Oct 15;22(20):4136-47. doi: 10.1093/hmg/ddt262. Epub 2013 Jun 4.
Disappearance of TAR-DNA-binding protein 43 kDa (TDP-43) from the nucleus contributes to the pathogenesis of amyotrophic lateral sclerosis (ALS), but the nuclear function of TDP-43 is not yet fully understood. TDP-43 associates with nuclear bodies including Gemini of coiled bodies (GEMs). GEMs contribute to the biogenesis of uridine-rich small nuclear RNA (U snRNA), a component of splicing machinery. The number of GEMs and a subset of U snRNAs decrease in spinal muscular atrophy, a lower motor neuron disease, suggesting that alteration of U snRNAs may also underlie the molecular pathogenesis of ALS. Here, we investigated the number of GEMs and U11/12-type small nuclear ribonucleoproteins (snRNP) by immunohistochemistry and the level of U snRNAs using real-time quantitative RT-PCR in ALS tissues. GEMs decreased in both TDP-43-depleted HeLa cells and spinal motor neurons in ALS patients. Levels of several U snRNAs decreased in TDP-43-depleted SH-SY5Y and U87-MG cells. The level of U12 snRNA was decreased in tissues affected by ALS (spinal cord, motor cortex and thalamus) but not in tissues unaffected by ALS (cerebellum, kidney and muscle). Immunohistochemical analysis revealed the decrease in U11/12-type snRNP in spinal motor neurons of ALS patients. These findings suggest that loss of TDP-43 function decreases the number of GEMs, which is followed by a disturbance of pre-mRNA splicing by the U11/U12 spliceosome in tissues affected by ALS.
TDP-43 从细胞核中的消失有助于肌萎缩侧索硬化症（ALS）的发病机制，但 TDP-43 的核功能尚未完全理解。TDP-43 与包括卷曲体双子星（GEMs）在内的核体结合。GEMs 有助于富含尿嘧啶的小核 RNA（U snRNA）的生物发生，U snRNA 是剪接机制的组成部分。在脊髓性肌萎缩症（一种运动神经元疾病）中，GEMs 的数量和一部分 U snRNA 减少，这表明 U snRNA 的改变也可能是 ALS 分子发病机制的基础。在这里，我们通过免疫组织化学研究了 GEMs 和 U11/12 型小核核糖核蛋白（snRNP）的数量，并用实时定量 RT-PCR 研究了 ALS 组织中 U snRNA 的水平。在 TDP-43 耗尽的 HeLa 细胞和 ALS 患者的脊髓运动神经元中，GEMs 减少。在 TDP-43 耗尽的 SH-SY5Y 和 U87-MG 细胞中，几种 U snRNA 的水平降低。U12 snRNA 的水平在受 ALS 影响的组织（脊髓、运动皮层和丘脑）中降低，但在不受 ALS 影响的组织（小脑、肾脏和肌肉）中不降低。免疫组织化学分析显示 ALS 患者脊髓运动神经元中 U11/12 型 snRNP 减少。这些发现表明 TDP-43 功能丧失会减少 GEMs 的数量，随后受 ALS 影响的组织中 U11/U12 剪接体的前体 mRNA 剪接受到干扰。
