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GABA transporter 1 is a promising drug target for CUL4B mutation-associated epilepsy

Acta Pharmacologica Sinica volume 46, pages 1580–1591 (2025)Cite this article

Abstract

Cullin 4B (CUL4B) is the scaffold protein in the CUL4B-RING E3 ubiquitin ligase (CRL4B) complex. Loss-of-function mutations in the human CUL4B gene result in syndromic X-linked intellectual disability (XLID). In addition to intellectual disability, patients with CUL4B mutations exhibit epilepsy. To date, the mechanism underlying epilepsy associated with CUL4B mutation has not been elucidated. Here, we show that male mice with Cul4b deleted in the nervous system are more susceptible to both pentylenetetrazole (PTZ)- and kainic acid (KA)-induced epilepsy and exhibit spontaneous epilepsy without any chemical inducers. We identify the CRL4B complex as an E3 ubiquitin ligase that targets GABA transporter 1 (GAT1). CUL4B deletion in male mice results in GAT1 accumulation and increased GABA reuptake, leading to impaired GABA-mediated inhibitory synaptic transmission. Treating CUL4B-deficient mice with the GAT1 inhibitor tiagabine effectively reverses the increased susceptibility to chemical-induced epilepsy and attenuates spontaneous epilepsy without the use of chemical inducers. We further confirm the role of CUL4B in the regulation of GAT1 levels and GABA uptake in neurons and astrocytes differentiated from induced pluripotent stem cells (iPSCs) derived from patients with CUL4B loss-of-function mutations. Our work reveals a novel mechanism underlying the pathogenesis of epilepsy and identifies a promising drug target for treating CUL4B mutation-associated epilepsy.

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Fig. 1: Lack of CUL4B in the nervous system increases epilepsy susceptibility in mice.
Fig. 2: Loss of CUL4B impairs inhibitory synaptic transmission.
Fig. 3: Lack of CUL4B in the nervous system results in increased GAT1 levels and GABA uptake.
Fig. 4: GAT1 inhibition blocks decreased tonic inhibition and increased seizure susceptibility caused by depletion of CUL4B.
Fig. 5: CRL4B functions as an E3 ligase for GAT1.
Fig. 6: Lack of CUL4B enhances GAT1 expression and GABA uptake in human iPSCs, iPSC-derived neurons, and iPSC-derived astrocytes.
Fig. 7: The mechanism underlying epilepsy associated with CUL4B mutations.

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Data availability

All the raw data supporting the findings of this study are available from the corresponding authors upon request.

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Acknowledgements

We thank the Translational Medicine Core Facility of Shandong University and the School of Basic Medical Sciences Core Facility of Shandong University for consultation and instrument availability. This work was supported by grants from the National Key R&D Program of China (2022YFC2703700 [2022YFC2703701] to YQG and 2022YFC2703700 [2022YFC2703703] to GPS) and the National Natural Science Foundation of China (32370652 and 82171851 to YQG; 31970559 to BCJ).

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Author notes

  1. These authors contributed equally: Gong-ping Sun, Bai-chun Jiang, Yao-qin Gong

Authors and Affiliations

  1. The Key Laboratory of Experimental Teratology of the Ministry of Education and Department of Genetics, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, 250012, China

    Wei Jiang, Yan-yan Ma, Yu-feng Wang, Shu-xian Chu, Yang-fan Gao, Mo-lin Wang, Yong-xin Zou, Qiao Liu, Yu Song, Bai-chun Jiang & Yao-qin Gong

  2. The Key Laboratory of Experimental Teratology of the Ministry of Education and Department of Histology and Embryology, School of Basic Medical Sciences, Cheeloo College of Medicine, Shandong University, Jinan, 250012, China

    Shi-qi Jin, Rui-qi Yu & Gong-ping Sun

  3. Key Laboratory for Neurodegenerative Disorders of the Ministry of Education, Capital Medical University, Beijing, 100053, China

    Yan Zheng

  4. School of Basic Medical Sciences, Beijing Key Laboratory of Neural Regeneration and Repair & Beijing Laboratory of Oral Health, Capital Medical University, Beijing, 100069, China

    Chen Zhang

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Contributions

YQG, BCJ, and GPS conceived the study concept and design. WJ performed most of the experiments. YYM helped establish the iPSCs. YFW, SQJ, RQY, SXC, and YFG helped establish the experiments. CZ, YZ, MLW, YXZ, QL, and YS participated in the acquisition, analysis, and interpretation of the data. YQG, BCJ, and GPS wrote and revised the manuscript.

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Correspondence to Gong-ping Sun, Bai-chun Jiang or Yao-qin Gong.

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Jiang, W., Ma, Yy., Wang, Yf. et al. GABA transporter 1 is a promising drug target for CUL4B mutation-associated epilepsy. Acta Pharmacol Sin 46, 1580–1591 (2025). https://doi.org/10.1038/s41401-025-01490-1

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