Santhakumar Vijjayalakshmi, Subramanian Deepak, Eisenberg Carol, Huang Andrew, Baek Jiyeon, Naveed Haniya, Komatireddy Samiksha, Shiflett Michael, Tran Tracy
University of California Riverside.
Res Sq. 2024 Feb 9:rs.3.rs-3922129. doi: 10.21203/rs.3.rs-3922129/v1.
Dysregulation of development, migration, and function of interneurons, collectively termed interneuronopathies, have been proposed as a shared mechanism for autism spectrum disorders (ASDs) and childhood epilepsy. Neuropilin-2 (Nrp2), a candidate ASD gene, is a critical regulator of interneuron migration from the median ganglionic eminence (MGE) to the pallium, including the hippocampus. While clinical studies have identified Nrp2 polymorphisms in patients with ASD, whether dysregulation of Nrp2-dependent interneuron migration contributes to pathogenesis of ASD and epilepsy has not been tested. We tested the hypothesis that the lack of Nrp2 in MGE-derived interneuron precursors disrupts the excitation/inhibition balance in hippocampal circuits, thus predisposing the network to seizures and behavioral patterns associated with ASD. Embryonic deletion of Nrp2 during the developmental period for migration of MGE derived interneuron precursors (iCKO) significantly reduced parvalbumin, neuropeptide Y, and somatostatin positive neurons in the hippocampal CA1. Consequently, when compared to controls, the frequency of inhibitory synaptic currents in CA1 pyramidal cells was reduced while frequency of excitatory synaptic currents was increased in iCKO mice. Although passive and active membrane properties of CA1 pyramidal cells were unchanged, iCKO mice showed enhanced susceptibility to chemically evoked seizures. Moreover, iCKO mice exhibited selective behavioral deficits in both preference for social novelty and goal-directed learning, which are consistent with ASD-like phenotype. Together, our findings show that disruption of developmental Nrp2 regulation of interneuron circuit establishment, produces ASD-like behaviors and enhanced risk for epilepsy. These results support the developmental interneuronopathy hypothesis of ASD epilepsy comorbidity.
发育、迁移及功能的失调，统称为中间神经元病变，已被提出作为自闭症谱系障碍（ASD）和儿童癫痫的共同机制。神经纤毛蛋白-2（Nrp2）是一种ASD候选基因，是中间神经元从内侧神经节隆起（MGE）迁移至包括海马体在内的大脑皮层的关键调节因子。虽然临床研究已在ASD患者中鉴定出Nrp2多态性，但Nrp2依赖性中间神经元迁移失调是否导致ASD和癫痫的发病机制尚未得到验证。我们验证了这样一个假设，即MGE衍生的中间神经元前体细胞中Nrp2的缺失会破坏海马回路中的兴奋/抑制平衡，从而使网络易患癫痫和与ASD相关的行为模式。在MGE衍生的中间神经元前体细胞迁移的发育时期对Nrp2进行胚胎期缺失（iCKO），显著减少了海马CA1区小白蛋白、神经肽Y和生长抑素阳性神经元的数量。因此，与对照组相比，iCKO小鼠CA1锥体细胞中抑制性突触电流的频率降低，而兴奋性突触电流的频率增加。虽然CA1锥体细胞的被动和主动膜特性没有改变，但iCKO小鼠对化学诱导的癫痫发作表现出更高的易感性。此外，iCKO小鼠在对社交新奇性的偏好和目标导向学习方面均表现出选择性行为缺陷，这与ASD样表型一致。总之，我们的研究结果表明，发育过程中Nrp2对中间神经元回路建立的调节受到破坏，会产生ASD样行为并增加癫痫风险。这些结果支持了ASD癫痫共病的发育性中间神经元病变假说。
