Saha Madhurima, Mitsuhashi Satomi, Jones Michael D, Manko Kelsey, Reddy Hemakumar M, Bruels Christine C, Cho Kyung-Ah, Pacak Christina A, Draper Isabelle, Kang Peter B
Division of Pediatric Neurology, Department of Pediatrics, University of Florida College of Medicine, Gainesville, FL 32610, USA.
Department of Neurology, Boston Children's Hospital and Harvard Medical School, Boston, MA 02115, USA.
Hum Mol Genet. 2017 Aug 1;26(15):2984-3000. doi: 10.1093/hmg/ddx189.
Mutations in MEGF10 cause early onset myopathy, areflexia, respiratory distress, and dysphagia (EMARDD), a rare congenital muscle disease, but the pathogenic mechanisms remain largely unknown. We demonstrate that short hairpin RNA (shRNA)-mediated knockdown of Megf10, as well as overexpression of the pathogenic human p.C774R mutation, leads to impaired proliferation and migration of C2C12 cells. Myoblasts from Megf10-/- mice and Megf10-/-/mdx double knockout (dko) mice also show impaired proliferation and migration compared to myoblasts from wild type and mdx mice, whereas the dko mice show histological abnormalities that are not observed in either single mutant mouse. Cell proliferation and migration are known to be regulated by the Notch receptor, which plays an essential role in myogenesis. Reciprocal co-immunoprecipitation studies show that Megf10 and Notch1 interact via their respective intracellular domains. These interactions are impaired by the pathogenic p.C774R mutation. Megf10 regulation of myoblast function appears to be mediated at least in part via interactions with key components of the Notch signaling pathway, and defects in these interactions may contribute to the pathogenesis of EMARDD.
MEGF10基因的突变会导致早发性肌病、无反射、呼吸窘迫和吞咽困难（EMARDD），这是一种罕见的先天性肌肉疾病，但其致病机制在很大程度上仍不清楚。我们证明，短发夹RNA（shRNA）介导的Megf10基因敲低以及致病性人类p.C774R突变的过表达，会导致C2C12细胞的增殖和迁移受损。与野生型和mdx小鼠的成肌细胞相比，Megf10基因敲除小鼠和Megf10基因敲除/mdx双敲除（dko）小鼠的成肌细胞也表现出增殖和迁移受损，而dko小鼠表现出的组织学异常在两种单突变小鼠中均未观察到。已知细胞增殖和迁移受Notch受体调节，Notch受体在肌生成中起重要作用。相互免疫共沉淀研究表明，Megf10和Notch1通过它们各自的细胞内结构域相互作用。这些相互作用因致病性p.C774R突变而受损。Megf10对成肌细胞功能的调节似乎至少部分是通过与Notch信号通路的关键成分相互作用介导的，这些相互作用的缺陷可能导致EMARDD的发病机制。
