Marsan Elise, Ishida Saeko, Schramm Adrien, Weckhuysen Sarah, Muraca Giuseppe, Lecas Sarah, Liang Ning, Treins Caroline, Pende Mario, Roussel Delphine, Le Van Quyen Michel, Mashimo Tomoji, Kaneko Takehito, Yamamoto Takashi, Sakuma Tetsushi, Mahon Séverine, Miles Richard, Leguern Eric, Charpier Stéphane, Baulac Stéphanie
INSERM, U1127, ICM, F-75013 Paris, France; CNRS, UMR 7225, ICM, F-75013 Paris, France; Sorbonne Universités, UPMC Univ Paris 06, UMR S 1127, F-75013 Paris, France; Institut du Cerveau et de la Moelle épinière, ICM, F-75013 Paris, France.
Institut Necker-Enfants Malades, CS 61431, Paris, France; INSERM, U1151, F-75014 Paris, France; Université Paris Descartes, Sorbonne Paris Cité, F-75006 Paris, France.
Neurobiol Dis. 2016 May;89:180-9. doi: 10.1016/j.nbd.2016.02.010. Epub 2016 Feb 9.
DEP-domain containing 5 (DEPDC5), encoding a repressor of the mechanistic target of rapamycin complex 1 (mTORC1) signaling pathway, has recently emerged as a major gene mutated in familial focal epilepsies and focal cortical dysplasia. Here we established a global knockout rat using TALEN technology to investigate in vivo the impact of Depdc5-deficiency. Homozygous Depdc5(-/-) embryos died from embryonic day 14.5 due to a global growth delay. Constitutive mTORC1 hyperactivation was evidenced in the brains and in cultured fibroblasts of Depdc5(-/-) embryos, as reflected by enhanced phosphorylation of its downstream effectors S6K1 and rpS6. Consistently, prenatal treatment with mTORC1 inhibitor rapamycin rescued the phenotype of Depdc5(-/-) embryos. Heterozygous Depdc5(+/-) rats developed normally and exhibited no spontaneous electroclinical seizures, but had altered cortical neuron excitability and firing patterns. Depdc5(+/-) rats displayed cortical cytomegalic dysmorphic neurons and balloon-like cells strongly expressing phosphorylated rpS6, indicative of mTORC1 upregulation, and not observed after prenatal rapamycin treatment. These neuropathological abnormalities are reminiscent of the hallmark brain pathology of human focal cortical dysplasia. Altogether, Depdc5 knockout rats exhibit multiple features of rodent models of mTORopathies, and thus, stand as a relevant model to study their underlying pathogenic mechanisms.
含DEP结构域蛋白5（DEPDC5）编码雷帕霉素机制靶点复合物1（mTORC1）信号通路的一种抑制因子，最近已成为家族性局灶性癫痫和局灶性皮质发育异常中发生突变的主要基因。在此，我们利用TALEN技术建立了一种全球敲除大鼠，以在体内研究Depdc5缺陷的影响。纯合子Depdc5（-/-）胚胎在胚胎期第14.5天因整体生长延迟而死亡。在Depdc5（-/-）胚胎的大脑和培养的成纤维细胞中证实了组成型mTORC1过度激活，这可通过其下游效应器S6K1和rpS6磷酸化增强来反映。同样，用mTORC1抑制剂雷帕霉素进行产前治疗可挽救Depdc5（-/-）胚胎的表型。杂合子Depdc5（+/-）大鼠发育正常，未出现自发性电临床发作，但皮质神经元兴奋性和放电模式发生改变。Depdc5（+/-）大鼠表现出皮质巨细胞发育异常神经元和强烈表达磷酸化rpS6的气球样细胞，表明mTORC1上调，产前雷帕霉素治疗后未观察到这种情况。这些神经病理学异常让人联想到人类局灶性皮质发育异常的标志性脑病理学特征。总之，Depdc5基因敲除大鼠表现出mTOR病啮齿动物模型的多种特征，因此，是研究其潜在致病机制的相关模型。
