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Functional characterization of novel NPRL3 mutations identified in three families with focal epilepsy

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Abstract

Focal epilepsy accounts for 60% of all forms of epilepsy, but the pathogenic mechanism is not well understood. In this study, three novel mutations in NPRL3 (nitrogen permease regulator-like 3), c.937_945del, c.1514dupC and 6,706-bp genomic DNA (gDNA) deletion, were identified in three families with focal epilepsy by linkage analysis, whole exome sequencing (WES) and Sanger sequencing. NPRL3 protein is a component of the GATOR1 complex, a major inhibitor of mTOR signaling. These mutations led to truncation of the NPRL3 protein and hampered the binding between NPRL3 and DEPDC5, which is another component of the GATOR1 complex. Consequently, the mutant proteins enhanced mTOR signaling in cultured cells, possibly due to impaired inhibition of mTORC1 by GATOR1. Knockdown of nprl3 in Drosophila resulted in epilepsy-like behavior and abnormal synaptic development. Taken together, these findings expand the genotypic spectrum of NPRL3-associated focal epilepsy and provide further insight into how NPRL3 mutations lead to epilepsy.

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Acknowledgements

This work was supported by the National Natural Science Foundation of China (32270663, 31871262, U20A20355, 32022035), Shanghai Municipal Science and Technology Major Project (2018SHZDZX05), and the Ministry of Science and Technology of China STI 2030-Major Projects (2021ZD0203202). We would like to thank all the participants in this study. We would also like to thank the Tsinghua Fly Center for providing fly stocks.

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Authors and Affiliations

  1. Key Laboratory of Molecular Biophysics of Ministry of Education, College of Life Science and Technology, Huazhong University of Science and Technology (HUST), Wuhan, 430074, China

    Shiyue Du, Li Song, Hongying Ma, Rui Chen, Junyu Luo, Hao Sun, Ping Yi, Mugen Liu & Luoying Zhang

  2. Department of Neurology, Xiangya Hospital, Central South University, Changsha, 410008, China

    Sheng Zeng, Jifeng Guo & Beisha Tang

  3. Department of Geriatrics, The Second Xiangya Hospital, Central South University, Changsha, 410011, China

    Sheng Zeng

  4. National Reference Laboratory of Veterinary Drug Residues and MAO Key Laboratory for Detection of Veterinary Drug Residues, Huazhong Agricultural University, Wuhan, 430070, China

    Xu Wang

  5. Institute of Neuroscience, State Key Laboratory of Neuroscience, Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, 200031, China

    Tingbin Ma, Xuan Xu, Hao Sun & Jing Yu Liu

  6. Department of Neurology, Union Hospital of HUST, Wuhan, 430022, China

    Yaling Huang & Tao Wang

  7. Institute of Neuroscience and Department of Neurology of the Second Affiliated Hospital of Guangzhou Medical University; Key Laboratory of Neurogenetics and Channelopathies of Guangdong Province and the Ministry of Education of China, Guangzhou Medical University, Guangzhou, 510260, China

    Wei-Ping Liao

  8. Hubei Province Key Laboratory of Oral and Maxillofacial Development and Regeneration, Wuhan, 430022, China

    Luoying Zhang

  9. Key Laboratory of Hunan Province in Neurodegenerative Disorders, Central South University, Changsha, 410008, China

    Beisha Tang

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  1. Shiyue Du
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Du, S., Zeng, S., Song, L. et al. Functional characterization of novel NPRL3 mutations identified in three families with focal epilepsy. Sci. China Life Sci. 66, 2152–2166 (2023). https://doi.org/10.1007/s11427-022-2313-1

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