Elevated Astrocytic NFAT5 of the hippocampus increases epilepsy susceptibility in hypoxic-ischemic mice

Xianglei Jia; Jian Xu; Yan Zhang; Shuo Kong; Xuelei Cheng; Ningyang Wu; Song Han; Jun Yin; Wanhong Liu; Xiaohua He; Yuanteng Fan; Yumin Liu; Taoxiang Chen; Biwen Peng

doi:10.1111/epi.18235

Elevated Astrocytic NFAT5 of the hippocampus increases epilepsy susceptibility in hypoxic-ischemic mice

Epilepsia. 2024 Dec 26. doi: 10.1111/epi.18235. Online ahead of print.

Authors

Xianglei Jia¹, Jian Xu², Yan Zhang¹, Shuo Kong¹, Xuelei Cheng¹, Ningyang Wu¹, Song Han³, Jun Yin³, Wanhong Liu⁴, Xiaohua He³, Yuanteng Fan⁵, Yumin Liu⁵, Taoxiang Chen¹, Biwen Peng¹

Affiliations

¹ Department of Physiology, School of Basic Medical Sciences, Wuhan University, Wuhan, China.
² Clinical Laboratory, Weifang Maternal and Child Health Hospital, Weifang, China.
³ Department of Pathophysiology, School of Basic Medical Sciences, Wuhan University, Wuhan, China.
⁴ Department of Immunology, School of Basic Medical Sciences, Wuhan University, Wuhan, China.
⁵ Department of Neurology, Zhongnan Hospital, Wuhan University, Wuhan, China.

PMID: 39724278
DOI: 10.1111/epi.18235

Abstract

Objective: Hypoxic-ischemic brain damage (HIBD) is a leading cause of neonatal mortality, resulting in brain injury and persistent seizures that can last into the late neonatal period and beyond. Effective treatments and interventions for infants affected by hypoxia-ischemia remain lacking. Clinical investigations have indicated an elevation of nuclear factor of activated T cells 5 (NFAT5) in whole blood from umbilical cords of severely affected HIBD infants with epilepsy. Experimental research has demonstrated that NFAT5 has ambivalent effects on neuroprotection and neurologic damage. However, the mechanistic role of NFAT5 in HIBD remains unclear. This investigation aims to further clarify the role of NFAT5 in epilepsy following HIBD insult.

Methods: We created a neonatal HIBD mouse model through left common carotid artery occlusion. By specifically knocking down astrocytic NFAT5 and its downstream molecule, Nedd4-2, using hippocampal delivery of adeno-associated virus 5-driven targeted shRNA, we investigated the role of astrocytic NFAT5 in epilepsy susceptibility in HIBD mice. This was assessed through electroencephalographic recordings, behavioral observations in vivo, and whole-cell recordings of hippocampal neuronal activity. In vitro, we evaluated the effects of astrocytic NFAT5 alteration on Kir4.1 expression and I_Kir4.1 in both brain slices from HIBD mice and cultured astrocytes treated with oxygen-glucose deprivation/reoxygenation.

Results: Hypoxia-ischemia-induced upregulation of hippocampal NFAT5 occurs in astrocytes rather than in neurons. This upregulation leads to increased expression of the ubiquitin ligase Nedd4-2, resulting in excessive degradation of Kir4.1 in astrocytes. Consequently, astrocytic function in buffering extracellular K⁺ is impaired, causing depolarization of the resting potential and enhanced neuronal discharge. This disruption ultimately affects local neural network balance and increases susceptibility to epilepsy. In contrast, inhibiting or knocking down astrocytic NFAT5 almost completely reverses these effects.

Significance: Our findings suggest that manipulating the NFAT5-Nedd4-2-Kir4.1 axis in astrocytes could provide a potential therapeutic strategy for the epileptic complications of HIBD.

Keywords: NFAT5; astrocyte; epilepsy; hypoxic–ischemic encephalopathy; neonatal.

Abstract

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