ZDHHC8 critically regulates seizure susceptibility in epilepsy

Abstract

Epilepsy is one of the most prevalent and drug-refractory neurological disorders. Zinc finger DHHC-type containing 8 (ZDHHC8) is a putative palmitoyltransferase that is highly expressed in the brain. However, the impact of ZDHHC8 on seizures remains unclear. We aimed to explore the association of ZDHHC8 with epilepsy and investigate its in epileptogenesis in in vivo and in vitro models through behavioral, electrophysiological, and pathological studies. We used kainic acid- and pilocarpine-induced C57BL/6 mice and magnesium-free-induced pyramidal neurons as experimental epileptic models in this study. We first found increased ZDHHC8 expression in the brains of temporal lobe epilepsy (TLE) patients, similar to that observed in chronic epileptic mice, strongly suggesting that ZDHHC8 is correlated with human epilepsy. In the in vitro seizure models, knocking down ZDHHC8 using recombinant adeno-associated virus (rAAV) delayed seizure precipitation and decreased chronic spontaneous recurrent seizures (SRSs) and epileptiform-like discharges, while ZDHHC8 overexpression had the opposite effect. ZDHHC8 levels were consistent with seizure susceptibility in induced mice with SRSs. In an in vitro magnesium-free model, neuronal hyperexcitability and hypersynchrony were reduced in ZDHHC8-knockdown neurons but were increased in ZDHHC8-overexpressing neurons. To further explore the potential mechanisms, we observed that ZDHHC8 had a significant modulatory effect on 2-amino-3-(5-methyl-3-oxo-1,2-oxazol-4-yl) propanoic acid (AMPA) receptor-related excitatory, but not inhibitory, glutamatergic synaptic neurotransmission, further affecting the inward rectification of AMPA currents in acute hippocampal slices in whole-cell recordings. ZDHHC8 facilitated GluA1 trafficking to the neuronal surface in the hippocampus, as shown by immunoprecipitation and Western blotting. These results suggest that ZDHHC8 may promote the generation and propagation of seizures in humans and that knocking down ZDHHC8 might produce anti-epileptogenic effects in drug-resistant epilepsy. Our study provides evidence that may facilitate the development of an alternative approach for the treatment of epilepsy by modulating AMPA/GluA1-mediated neurotransmission.

Inhibition of Nwd1 activity attenuates neuronal hyperexcitability and GluN2B phosphorylation in the hippocampus

“…For in vivo viral injections, adult mice (18–25 g, 8–10 weeks old) were anesthetized with 3.5% chloral hydrate and then mounted in a stereotactic headframe containing a mouse adaptor (Reward Life Technology Co., Ltd., China), as described previously [27,28]. The viral vectors were bilaterally injected into the dorsal hippocampus region (anteroposterior (AP) = −1.8 mm, mediolateral (ML) = 1.2 mm, dorsoventral (DV) = 1.5 mm) with a microsyringe (Hamilton, Reno, NV) filled with 2.0 μL of virus.…”

“…The KA-induced acute seizures were produced essentially as previously described [[28], [29], [30]]. KA (Sigma-Aldrich, Cat# K0250) was administered to mice at a dose of 20 mg/kg (diluted in 0.9% NaCl solution) via intraperitoneal injection.…”

Olfactomedin-3 Enhances Seizure Activity by Interacting With AMPA Receptors in Epilepsy Models

“…In our study, all brain tissue samples were randomly selected from our brain tissue bank (Yang et al, 2018). The tissues were collected from 24 patients [13 males and 11 females; mean age 34.54 ± 1.89 years (18-53 years); mean disease course 11.33 ± 5.47 years (4-25 years)] who had been diagnosed with TLE and had subsequently undergone surgical resection.…”

AMPAR Palmitoylation Tunes Synaptic Strength: Implications for Synaptic Plasticity and Disease

“…Indeed, GluA1 expression and phosphorylation of the C-terminal tail are necessary for some forms of plasticity (Jensen et al, 2003;Goel et al, 2011;Zhou et al, 2018). Further, dysregulation of GluA1 or altered post-translational modification of its C terminus is implicated in neurological disorders, including epilepsy (Zhang and Abdullah, 2013;Yang et al, 2018). However, little is known about the role of GluA1 palmitoylation in these processes.…”

“…That is, correcting the balance between excitation and inhibition may be insufficient to fully reverse epileptic activity in some cases; instead, targeting the receptor subsystem underlying neural hyperexcitability may be necessary to achieve better treatment outcomes. Targeting AMPAR palmitoylation, therefore, might broaden the therapeutic range to circumvent limitations of conventional antiepileptic drugs and provide therapeutic value for epilepsy (Yang et al, 2018).…”