The RNA Institute, University at Albany, State University of New York, 1400 Washington Avenue, Albany, NY 12222, United States.
Department of Biological Sciences, University at Albany, State University of New York, 1400 Washington Avenue, Albany, NY 12222, United States.
Hum Mol Genet. 2024 Nov 5;33(21):1873-1886. doi: 10.1093/hmg/ddae125.
Myotonic dystrophy type 1 (DM1) is a heterogeneous multisystemic disease caused by a CTG repeat expansion in DMPK. Transcription of the expanded allele produces toxic CUG repeat RNA that sequesters the MBNL family of alternative splicing (AS) regulators into ribonuclear foci, leading to pathogenic mis-splicing. To identify genetic modifiers of toxic CUG RNA levels and the spliceopathy, we performed a genome-scale siRNA screen using an established HeLa DM1 repeat-selective screening platform. We unexpectedly identified core spliceosomal proteins as a new class of modifiers that rescue the spliceopathy in DM1. Modest knockdown of one of our top hits, SNRPD2, in DM1 fibroblasts and myoblasts, significantly reduces DMPK expression and partially rescues MBNL-regulated AS dysfunction. While the focus on the DM1 spliceopathy has centered around the MBNL proteins, our work reveals an unappreciated role for MBNL:spliceosomal protein stoichiometry in modulating the spliceopathy, revealing new biological and therapeutic avenues for DM1.
肌强直性营养不良 1 型（DM1）是一种异质性多系统疾病，由 DMPK 中的 CTG 重复扩展引起。扩增等位基因的转录产生有毒的 CUG 重复 RNA，将 MBNL 家族的可变剪接（AS）调节剂隔离到核糖核仁焦点中，导致致病的剪接错误。为了鉴定毒性 CUG RNA 水平和剪接病的遗传修饰因子，我们使用已建立的 HeLa DM1 重复选择性筛选平台进行了全基因组规模的 siRNA 筛选。我们出人意料地发现核心剪接体蛋白是一类新的调节剂，可挽救 DM1 中的剪接病。在 DM1 成纤维细胞和肌母细胞中适度敲低我们的一个顶级命中物 SNRPD2，可显著降低 DMPK 的表达并部分挽救 MBNL 调节的 AS 功能障碍。虽然 DM1 剪接病的焦点一直集中在 MBNL 蛋白上，但我们的工作揭示了 MBNL：剪接体蛋白比例在调节剪接病中的未被认识的作用，为 DM1 揭示了新的生物学和治疗途径。
