Pathogenic DDX39A Variant Disrupts Nuclear Homeostasis and Causes an Early-Onset Neurodegenerative Disorder With Cerebral Atrophy.

IF 2.3 3区 医学 Q2 GENETICS & HEREDITY
S Rehan Ahmad, Abdullah M AlShahrani, Natchimuthu Vijayakumar, Anupriya Kumari
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引用次数: 0

Abstract

Neurodevelopmental disorders arising from mutations in RNA-processing factors are increasingly recognized but remain mechanistically underexplored. Here, we identify that variant (c.485A>C; p.Lys137Gln) in DDX39A in a 7-month-old proband presenting with global developmental delay, microcephaly, seizures, hypotonia, and brain atrophy with corpus callosum thinning. DDX39A encodes a DEAD-box RNA helicase essential for mRNA splicing and export via the TREX complex. Functional studies in proband-derived fibroblasts revealed that while transcript and protein levels of DDX39A-K137Q were unaffected, the mutant protein displayed aberrant nuclear clumping and failed to interact with the TREX component THOC1. Structural modeling demonstrated that Lys137 mediates critical inter- and intra-molecular interactions, which are disrupted by the K137Q substitution. This loss destabilizes the DDX39A-THOC1 interface, impairing TREX complex integrity. The mutant cells exhibited severe nuclear morphological abnormalities, disrupted nuclear lamina organization, and increased cell death. Transcriptomic network analysis and gene ontology revealed enrichment of DDX39A interactions in mRNA export, splicing, and nucleocytoplasmic transport-functions essential for neuronal development. Temporal and regional brain expression data showed that DDX39A is highly expressed during early postnatal life and across multiple brain regions, indicating its importance in early brain maturation. Our findings establish DDX39A-K137Q as a pathogenic variant that impairs nuclear RNA processing and structural homeostasis, leading to a severe neurodegenerative phenotype. This study identifies the role of RNA helicases in neurodevelopment and explores DDX39A as a novel gene implicated in pediatric neurodegenerative disease.

致病性DDX39A变异破坏核稳态并导致早发性神经退行性疾病伴脑萎缩
由rna加工因子突变引起的神经发育障碍被越来越多地认识到,但其机制仍未得到充分探讨。在这里,我们确定了该变体(C . 485a >C;p.Lys137Gln)在DDX39A中表达,在一个7个月大的先证儿中表现为整体发育迟缓、小头畸形、癫痫、强直低下和脑萎缩伴胼胝体变薄。DDX39A编码一个DEAD-box RNA解旋酶,对mRNA剪接和通过TREX复合体输出至关重要。先证衍生成纤维细胞的功能研究显示,虽然DDX39A-K137Q的转录物和蛋白水平未受影响,但突变蛋白表现出异常的核聚集,无法与TREX成分THOC1相互作用。结构建模表明,Lys137介导了关键的分子间和分子内相互作用,这些相互作用被K137Q取代所破坏。这种损失破坏了DDX39A-THOC1接口的稳定性,损害了TREX复合物的完整性。突变细胞表现出严重的核形态异常,核层组织破坏,细胞死亡增加。转录组网络分析和基因本体揭示了DDX39A在mRNA输出、剪接和核胞质转运功能中的相互作用的富集,这些功能是神经元发育所必需的。脑时间和区域表达数据显示,DDX39A在出生后早期高表达,并跨多个脑区域表达,表明其在早期脑成熟中的重要性。我们的研究结果表明,DDX39A-K137Q是一种致病性变异,可损害核RNA加工和结构稳态,导致严重的神经退行性表型。本研究确定了RNA解旋酶在神经发育中的作用,并探索了DDX39A作为一个涉及儿童神经退行性疾病的新基因。
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来源期刊
Clinical Genetics
Clinical Genetics 医学-遗传学
CiteScore
6.50
自引率
0.00%
发文量
175
审稿时长
3-8 weeks
期刊介绍: Clinical Genetics links research to the clinic, translating advances in our understanding of the molecular basis of genetic disease for the practising clinical geneticist. The journal publishes high quality research papers, short reports, reviews and mini-reviews that connect medical genetics research with clinical practice. Topics of particular interest are: • Linking genetic variations to disease • Genome rearrangements and disease • Epigenetics and disease • The translation of genotype to phenotype • Genetics of complex disease • Management/intervention of genetic diseases • Novel therapies for genetic diseases • Developmental biology, as it relates to clinical genetics • Social science research on the psychological and behavioural aspects of living with or being at risk of genetic disease
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