Mechanistic insights into the cellular effects of a novel FN1 variant associated with a spondylometaphyseal dysplasia
Mechanistic insights into the cellular effects of a novel FN1 variant associated with a spondylometaphyseal dysplasia
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DOI：
10.1111/cge.13424
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发表时间：
2018-11-01
影响因子：
3.5
通讯作者：
Schwarzbauer, J. E.
中科院分区：
文献类型：
--
作者：
Cadoff, E. B.;Sheffer, R.;Schwarzbauer, J. E.
以长骨和椎骨的发育性改变为特征的椎体发育不良症(SMD)。它有很大的表型多样性和多种遗传原因，包括最近与细胞外基质(ECM)蛋白纤维连接蛋白(FN)的新变体的联系，细胞外基质组装的调节因子，以及细胞外基质和正常细胞功能之间的关键联系。我们发现一位患者患有独特的SMD，类似于伴有角部骨折的SMD。患者经过19年以上的随访，表现为身材矮小、膝内翻、脊柱后凸和隆胸。X线片显示干骺端随时间消退的改变、椎体改变和小头状缺血性坏死。全外显子测序发现了一个新的杂合子FN1变异体(p.Cys97Trp)。利用质谱仪，在患者分离的原代真皮成纤维细胞的血浆和培养液中检测到突变的Fn，但突变的蛋白含量远低于野生型Fn。免疫荧光和免疫印迹分析表明，突变的成纤维细胞聚集的FN基质数量明显低于野生型细胞，并且突变的FN优先保留在内质网中。这项工作强调了FN在骨骼发育中的重要性，以及它在SMD亚型发病机制中的潜在作用。
Spondylometaphyseal dysplasia (SMD) is characterized by developmental changes in long bones and vertebrae. It has large phenotypic diversity and multiple genetic causes, including a recent link to novel variants in the extracellular matrix (ECM) protein fibronectin (FN), a regulator of ECM assembly and key link between the ECM and proper cell function. We identified a patient with a unique SMD, similar to SMD with corner fractures. The patient has been followed over 19 years and presents with short stature, genu varum, kyphoscoliosis, and pectus carinatum. Radiography shows metaphyseal changes that resolved over time, vertebral changes, and capitular avascular necrosis. Whole exome sequencing identified a novel heterozygous FN1 variant (p.Cys97Trp). Using mass spectroscopy, mutant FN was detected in plasma and in culture medium of primary dermal fibroblasts isolated from the patient, but mutant protein was much less abundant than wild-type FN. Immunofluorescence and immunoblotting analyses show that mutant fibroblasts assemble significantly lower amounts of FN matrix than wild-type cells, and mutant FN was preferentially retained within the endoplasmic reticulum. This work highlights the importance of FN in skeletal development, and its potential role in the pathogenesis of a subtype of SMD.