遗传性痉挛性截瘫(HSP)是一种退行性运动神经元疾病,其特征是下肢进行性痉挛和虚弱。HSP的最常见形式是由于SPG4基因单倍体不足。SPG4编码微管切断酶spastin。虽然,没有治疗SPG4-HSP的方法,诱导痉挛恢复的策略正在成为有前途的治疗方法。Spastin蛋白水平受聚泛素化和蛋白酶体介导的降解调节,以依赖neddylation的方式。然而,参与这一调控的分子参与者是未知的。这里,我们表明Cullin-4环E3泛素连接酶复合物(CRL4)调节spastin稳定性。CRL4的抑制通过防止其聚泛素化和随后在spastin丰富的和患者来源的SPG4单倍体不足的细胞中的降解来增加spastin水平。评价CRL4复合物在体内调节痉挛素的作用,我们开发了一个SPG4单倍体功能不全的果蝇模型,显示突触形态和运动活动的改变,在患者中观察到的表型缺陷。CRL4复合物的下调,在果蝇中高度保守,挽救在果蝇中观察到的spastin水平和表型缺陷。作为可能的药物治疗概念的证明,我们证明了通过NSC1892对CRL4复合物的化学失活,在果蝇模型和患者来源的细胞中,spastin水平的恢复和SPG4-HSP相关缺陷的改善.一起来看,这些发现表明,CRL4有助于调节spastin的稳定性,并且有可能通过阻断CRL4介导的spastin降解来诱导spastin恢复和挽救SPG4-HSP缺陷。
Hereditary spastic paraplegias (HSPs) are degenerative motor neuron diseases characterized by progressive spasticity and weakness in the lower limbs. The most common form of HSP is due to SPG4 gene haploinsufficiency. SPG4 encodes the microtubule severing enzyme
spastin. Although, there is no cure for SPG4-HSP, strategies to induce a spastin recovery are emerging as promising therapeutic approaches.
Spastin protein levels are regulated by poly-ubiquitination and proteasomal-mediated degradation, in a neddylation-dependent manner. However, the molecular players involved in this regulation are unknown. Here, we show that the Cullin-4-Ring E3 ubiquitin ligase complex (CRL4) regulates
spastin stability. Inhibition of CRL4 increases spastin levels by preventing its poly-ubiquitination and subsequent degradation in
spastin-proficient and in patient derived SPG4 haploinsufficient cells. To evaluate the role of CRL4 complex in spastin regulation in vivo, we developed a Drosophila melanogaster model of SPG4 haploinsufficiency which show alterations of synapse morphology and locomotor activity, recapitulating phenotypical defects observed in patients. Downregulation of the CRL4 complex, highly conserved in Drosophila, rescues spastin levels and the phenotypical defects observed in flies. As a proof of concept of possible pharmacological treatments, we demonstrate a recovery of spastin levels and amelioration of the SPG4-HSP-associated defects both in the fly model and in patient-derived cells by chemical inactivation of the CRL4 complex with NSC1892. Taken together, these findings show that CRL4 contributes to spastin stability regulation and that it is possible to induce spastin recovery and rescue of SPG4-HSP defects by blocking the CRL4-mediated
spastin degradation.