Abstract：
Charcot-Marie-Tooth disease type 1A (CMT1A) is the most common inherited peripheral neuropathy caused by a 1.5 megabase tandem duplication of chromosome 17 harboring the PMP22 gene. This dose-dependent overexpression of PMP22 results in disrupted Schwann cell myelination of peripheral nerves. To get better insights into the underlying pathogenic mechanisms in CMT1A, we investigated the role of PMP22 duplication on cellular homeostasis in CMT1A mouse models and in patient-derived induced pluripotent stem cells differentiated into Schwann cell precursors (iPSC-SCPs). We performed lipidomic profiling and bulk RNA sequencing on sciatic nerves of two developing CMT1A mouse models and on CMT1A patient derived iPSC-SCPs. For the sciatic nerves of the CMT1A mice, cholesterol and lipid metabolism was dose-dependently downregulated throughout development. For the CMT1A iPSC-SCPs, transcriptional analysis unveiled a strong suppression of genes related to autophagy and lipid metabolism. Gene ontology enrichment analysis identified disturbances in pathways related to plasma membrane components and cell receptor signaling. Lipidomic analysis confirmed the severe dysregulation in plasma membrane lipids, particularly sphingolipids, in CMT1A iPSC-SCPs. Furthermore, we identified reduced lipid raft dynamics, disturbed plasma membrane fluidity, and impaired cholesterol incorporation and storage, all of which could result from altered lipid storage homeostasis in the patient-derived CMT1A iPSC-SCPs. Importantly, this phenotype could be rescued by stimulating autophagy and lipolysis. We conclude that PMP22 duplication disturbs intracellular lipid storage and leads to a more disordered plasma membrane due to an alteration in the lipid composition, which ultimately may lead to impaired axo-glial interactions. Moreover, targeting lipid handling and metabolism could hold promise for the treatment of CMT1A patients.
摘要：
Charcot-Marie-Tooth病1A型（CMT1A）是最常见的遗传性周围神经病变，由携带PMP22基因的17号染色体1.5兆碱基串联重复引起。PMP22的这种剂量依赖性过表达导致周围神经的雪旺氏细胞髓鞘化被破坏。为了更好地了解CMT1A的潜在致病机制，我们在CMT1A小鼠模型和患者来源的诱导多能干细胞(iPSC-SCP)中研究了PMP22复制对细胞稳态的作用.我们对两个发育中的CMT1A小鼠模型的坐骨神经和CMT1A患者来源的iPSC-SCP进行了脂质组学分析和大量RNA测序。对于CMT1A小鼠的坐骨神经，在整个发育过程中,胆固醇和脂质代谢呈剂量依赖性下调.对于CMT1AiPSC-SCP，转录分析揭示了与自噬和脂质代谢相关的基因的强烈抑制。基因本体论富集分析确定了与质膜成分和细胞受体信号传导相关的通路中的干扰。脂质组学分析证实了质膜脂质的严重失调，尤其是鞘脂，在CMT1AiPSC-SCP中。此外，我们发现脂筏动力学减少，受干扰的质膜流动性，和受损的胆固醇掺入和储存，所有这些都可能是由于患者来源的CMT1AiPSC-SCP的脂质储存稳态改变所致.重要的是,这种表型可以通过刺激自噬和脂肪分解来挽救.我们得出的结论是，由于脂质成分的改变，PMP22复制会干扰细胞内脂质的储存，并导致更无序的质膜。最终可能导致受损的神经胶质相互作用。此外，靶向脂质处理和代谢可能为CMT1A患者的治疗带来希望。
