Human brain organoids reveal MGE interneuron defects independent of mTOR-hyperactivation in genetic focal epilepsy

The pathogenic mechanisms of non-acquired focal epilepsy (NAFE) are underexplored. As the most common monogenic cause of NAFE, the epileptogenic mechanism of mutations in the GTPase-Activating Protein Activity Toward Rags 1 (GATOR1) genes remains unclear. Here, using patient-derived neuron-type-specific organoids, we show that focal epilepsy-associated transcriptional dysregulation is highly pronounced in ventral GABAergic organoids (VGOs).

Patient VGOs exhibit significant impairments in GABAergic interneuron differentiation, migration, and functional GABA release. Mechanistically, these interneuron defects are independent of the canonical mTOR-hyperactivation and are instead driven by the deficiency of MAFB. MAFB expression is significantly decreased in both patient-derived VGOs and brain tissues.

MAFB knockdown leads to similar interneuron defects in VGOs. Importantly, MAFB overexpression rescues the abnormal phenotypes in patient VGOs. Collectively, our study reveals a non-canonical cellular and molecular mechanism underlying GATOR1-related focal epilepsy, providing a mechanistic basis for precise therapy.

The authors would like to thank the patients and healthy subjects for participating in the study. Yuwu Jiang and his team for their generous support in this study, particularly for providing the pathological brain tissue sections from patients with GATORopathy. The author would also like to extend their gratitude to ChatGPT for its assistance in refining the language and improving the readability of this manuscript.

This study was supported by the funding from the National Key R&D Program of China (grant 2022YFC2503802 to Jing Ding), National Natural Science Foundation of China (grant 82271499 to Jing Ding and grant 32450530 to Zhicheng Shao), the Joint Project of the Yangtze River Delta Science and Technology Innovation Community (grant 2024CSJZN0602 to Zhicheng Shao), and National Key Research and Development Program of China (grant 2024YFA1108000 to Zhicheng Shao). Department of Neurology, Zhongshan Hospital, Fudan University, Shanghai, China Yuling Yang, Yi Yan, Qin Wang, Yang Cai, Yao Zhao, Xin Wang, Zhicheng Shao & Jing Ding Children’s Medical Center, Peking University First Hospital, Beijing, China Institute for Translational Brain Research, Fudan University, Shanghai, China Pediatric Epilepsy Center, Peking University First Hospital, Beijing, China State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Fudan University, Shanghai, China Correspondence to Xin Wang, Zhicheng Shao or Jing Ding. The authors declare no competing interests.

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