Banerjee Ayan, Vest Katherine E, Pavlath Grace K, Corbett Anita H
Department of Biology, Emory University, Atlanta, GA 30322, USA.
Department of Pharmacology, Emory University School of Medicine, Atlanta, GA 30322, USA.
Nucleic Acids Res. 2017 Oct 13;45(18):10706-10725. doi: 10.1093/nar/gkx786.
The polyadenylate binding protein 1 (PABPN1) is a ubiquitously expressed RNA binding protein vital for multiple steps in RNA metabolism. Although PABPN1 plays a critical role in the regulation of RNA processing, mutation of the gene encoding this ubiquitously expressed RNA binding protein causes a specific form of muscular dystrophy termed oculopharyngeal muscular dystrophy (OPMD). Despite the tissue-specific pathology that occurs in this disease, only recently have studies of PABPN1 begun to explore the role of this protein in skeletal muscle. We have used co-immunoprecipitation and mass spectrometry to identify proteins that interact with PABPN1 in mouse skeletal muscles. Among the interacting proteins we identified Matrin 3 (MATR3) as a novel protein interactor of PABPN1. The MATR3 gene is mutated in a form of distal myopathy and amyotrophic lateral sclerosis (ALS). We demonstrate, that like PABPN1, MATR3 is critical for myogenesis. Furthermore, MATR3 controls critical aspects of RNA processing including alternative polyadenylation and intron retention. We provide evidence that MATR3 also binds and regulates the levels of long non-coding RNA (lncRNA) Neat1 and together with PABPN1 is required for normal paraspeckle function. We demonstrate that PABPN1 and MATR3 are required for paraspeckles, as well as for adenosine to inosine (A to I) RNA editing of Ctn RNA in muscle cells. We provide a functional link between PABPN1 and MATR3 through regulation of a common lncRNA target with downstream impact on paraspeckle morphology and function. We extend our analysis to a mouse model of OPMD and demonstrate altered paraspeckle morphology in the presence of endogenous levels of alanine-expanded PABPN1. In this study, we report protein-binding partners of PABPN1, which could provide insight into novel functions of PABPN1 in skeletal muscle and identify proteins that could be sequestered with alanine-expanded PABPN1 in the nuclear aggregates found in OPMD.
聚腺苷酸结合蛋白1（PABPN1）是一种在全身广泛表达的RNA结合蛋白，对RNA代谢的多个步骤至关重要。尽管PABPN1在RNA加工调控中起关键作用，但编码这种全身广泛表达的RNA结合蛋白的基因突变会导致一种特定形式的肌肉萎缩症，称为眼咽型肌营养不良症（OPMD）。尽管该疾病存在组织特异性病理，但直到最近，对PABPN1的研究才开始探索这种蛋白在骨骼肌中的作用。我们利用免疫共沉淀和质谱法来鉴定在小鼠骨骼肌中与PABPN1相互作用的蛋白。在相互作用的蛋白中，我们鉴定出Matrin 3（MATR3）是PABPN1的一种新型蛋白相互作用因子。MATR3基因在一种远端肌病和肌萎缩侧索硬化症（ALS）中发生突变。我们证明，与PABPN1一样，MATR3对肌生成至关重要。此外，MATR3控制RNA加工的关键方面，包括可变聚腺苷酸化和内含子保留。我们提供证据表明，MATR3还结合并调节长链非编码RNA（lncRNA）Neat1的水平，并且与PABPN1一起是正常副斑点功能所必需的。我们证明，PABPN1和MATR3是副斑点以及肌肉细胞中Ctn RNA的腺苷到次黄苷（A到I）RNA编辑所必需的。我们通过调控一个共同的lncRNA靶标，为PABPN1和MATR3之间提供了功能联系，该靶标对副斑点形态和功能具有下游影响。我们将分析扩展到OPMD小鼠模型，并证明在内源性丙氨酸扩展的PABPN1存在下副斑点形态发生改变。在这项研究中，我们报告了PABPN1的蛋白结合伙伴，这可以为PABPN1在骨骼肌中的新功能提供见解，并鉴定出在OPMD中发现的核聚集体中可能与丙氨酸扩展的PABPN1结合的蛋白。
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