Richardson Louise, Hughes Ruth, Johnson Colin A, Egginton Stuart, Peckham Michelle
School of Molecular and Cellular Biology, University of Leeds, Leeds, LS2 9JT, UK.
Faculty of Medicine, University of Leeds, Leeds, LS2 9JT, UK.
J Muscle Res Cell Motil. 2025 Jan 18. doi: 10.1007/s10974-024-09686-4.
Biallelic mutations in multiple EGF domain protein 10 (MEGF10) gene cause EMARDD (early myopathy, areflexia, respiratory distress and dysphagia) in humans, a severe recessive myopathy, associated with reduced numbers of PAX7 positive satellite cells. To better understand the role of MEGF10 in satellite cells, we overexpressed human MEGF10 in mouse H-2k-tsA58 myoblasts and found that it inhibited fusion. Addition of purified extracellular domains of human MEGF10, with (ECD) or without (EGF) the N-terminal EMI domain to H-2k-tsA58 myoblasts, showed that the ECD was more effective at reducing myoblast adhesion and fusion by day 7 of differentiation, yet promoted adhesion of myoblasts to non-adhesive surfaces, highlighting the importance of the EMI domain in these behaviours. We additionally tested the role of Megf10 in vivo using transgenic mice with reduced (Megf10) or no (Megf10) Megf10. We found that the extensor digitorum longus muscle had fewer anti-Pax7 stained cell nuclei and was less able to undergo hypertrophy in response to muscle overload concomitant with a lower level of satellite cell activation. Taken together, our data suggest that MEGF10 may promote satellite cell adhesion and survival and prevent premature fusion helping to explain its role in EMARDD.
多表皮生长因子结构域蛋白10（MEGF10）基因的双等位基因突变会导致人类患上EMARDD（早期肌病、无反射、呼吸窘迫和吞咽困难），这是一种严重的隐性肌病，与PAX7阳性卫星细胞数量减少有关。为了更好地理解MEGF10在卫星细胞中的作用，我们在小鼠H-2k-tsA58成肌细胞中过表达人MEGF10，发现它会抑制融合。将人MEGF10的纯化胞外结构域（有N端EMI结构域的ECD或无该结构域的EGF）添加到H-2k-tsA58成肌细胞中，结果显示，到分化第7天时，ECD在降低成肌细胞黏附和融合方面更有效，但能促进成肌细胞与非黏附表面的黏附，这突出了EMI结构域在这些行为中的重要性。我们还使用Megf10减少（Megf10）或缺失（Megf10）的转基因小鼠在体内测试了Megf10的作用。我们发现，趾长伸肌中抗Pax7染色的细胞核较少，并且在肌肉超负荷时对肥大的反应能力较弱，同时卫星细胞激活水平较低。综上所述，我们的数据表明，MEGF10可能促进卫星细胞黏附和存活，并防止过早融合，这有助于解释它在EMARDD中的作用。
