Molecular Mechanisms of Epileptic Encephalopathy Caused by KCNMA1 Loss-of-Function Mutations

Yao, Yu; Qu, Dongxiao; Jing, Xiaoping; Jia, Yuxiang; Zhong, Qi; Zhuo, Limin; Chen, Xingxing; Li, Guoyi; Tang, Lele; Zhu, Yudan; Zhang, Xuemei; Ji, Yonghua; Li, Zhiping; Tao, Jie

doi:10.3389/fphar.2021.775328

Cited by 14 publications

(12 citation statements)

References 48 publications

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“…37 Yao et al reported another de novo LOF KCNMA1 variant, p.(E155Q), in a Liang-Wang syndrome patient with febrile seizures, hyperactivity, repeated daze, poor language development and developmental delay. 38 In summary, in this study, we characterized four new patients with KCNMA1 variants, including p.(A172T), p.(A314T), p.(N536H) and p.(N995S), in detail. We found that two of these variants, p.(A172T) and p.(A314T), acted by a LOF mechanism, and were associated with Liang-Wang syndrome.…”

Section: Discussionmentioning

confidence: 94%

“…Graber et al reported a de novo heterozygous one bp deletion variant in KCNMA1 (c.112delG) in a Liang–Wang syndrome patient who presented with drug‐resistant epilepsy with severe developmental delay initially related to bilateral asymmetric frontal polymicrogyria since the age of 2 months 37 . Yao et al reported another de novo LOF KCNMA1 variant, p.(E155Q), in a Liang–Wang syndrome patient with febrile seizures, hyperactivity, repeated daze, poor language development and developmental delay 38 …”

Section: Discussionmentioning

confidence: 99%

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Identification and functional analysis of two new de novo KCNMA1 variants associated with Liang–Wang syndrome

et al. 2022

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Aim: Loss-of-function KCNMA1 variants cause Liang-Wang syndrome (MIM #618729), a newly identified multiple malformation syndrome with a broad spectrum of developmental and neurological phenotypes. However, the full spectrum of clinical features and underlying pathogenic mechanisms need full elucidation.Methods: Exome sequencing was used to identify pathogenic variants. Patchclamp recordings were performed to access the effects of KCNMA1 variants on BK channels. Total and membrane protein expression levels of BK channels were characterized using Western blotting. Results: We report identification and functional characterization of two new de novo loss-of-function KCNMA1 variants p.(A172T) and p.(A314T) with characteristics of Liang-Wang syndrome. Variant p.(A172T) is associated with developmental delay, cognitive impairment and ataxia. Mechanistically, p.(A172T) abolishes BK potassium current, inhibits Mg 2+ -dependent gating, but shifts conductance-voltage (G-V) curves to more positive potentials when complexed with WT channels. Variant p.(A314T) is associated with developmental delay, intellectual disability, cognitive impairment, mild ataxia and generalized epilepsy; suppresses BK current amplitude; and shifts G-V curves to more positive potentials when expressed with WT channels. In addition, two new patients with previously reported gain-of-function variants p.(N536H) and p.(N995S) are found to show epilepsy and paroxysmal dyskinesia as reported previously, but also exhibit additional symptoms of cognitive impairment and dysmorphic features. Furthermore, variants p.(A314T) and p.(N536H) reduced total and membrane levels of BK proteins. Conclusion: Our findings identified two new loss-of-function mutations of KCNMA1 associated with Liang-Wang syndrome, expanded the spectrum of clinical features associated with gain-of-function KCNMA1 variants and emphasized the overlapping features shared by gain-of-function and loss-of-function mutations.

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Section: Discussionmentioning

confidence: 94%

Section: Discussionmentioning

confidence: 99%

Identification and functional analysis of two new de novo KCNMA1 variants associated with Liang–Wang syndrome

et al. 2022

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“…However, since half of those harboring LOF variants also report seizures (Liang et al ., 2019; Miller et al ., 2021), including the H444Q and individuals with putative truncation alleles, Kcnma1 H444Q/WT and Kcnma1 —/— mice were assessed in parallel. No seizures have been previously reported in two established Kcnma1 —/— mouse models (Bailey et al ., 2019; ALM unpublished data), but spontaneous epilepsy was reported in a CRISPR-exon4 Kcnma1 —/— line (Yao et al ., 2021).…”

Section: Resultsmentioning

confidence: 99%

“…At present, there are no patients with homozygous KCNMA1 alleles validated as functionally null for channel activity (Miller et al ., 2021), but the ataxia, tremor, decreased strength, and hyperactivity in Kcnma1 —/— mice (Imlach et al ., 2008; Meredith et al ., 2004; Sausbier et al ., 2004; Typlt et al ., 2013; Wang et al ., 2020) are symptoms observed at lower incidence among patients. Lastly, our experimental conditions failed to corroborate the influence of LOF alleles on seizure propensity predicted from several animal studies (Ermolinsky et al ., 2008; Kuebler et al ., 2001; Pacheco Otalora et al ., 2008; Sheehan et al ., 2009; Shruti et al ., 2008; Yao et al ., 2021).…”

Section: Discussionmentioning

confidence: 99%

BK channel properties correlate with neurobehavioral severity in three KCNMA1-linked channelopathy mouse models

Park

Roache

Iffland

et al. 2022

Preprint

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KCNMA1 forms the pore of BK K+ channels, which regulate neuronal and muscle excitability. Recently, genetic screening identified heterozygous KCNMA1 variants in a subset of patients with debilitating paroxysmal non-kinesigenic dyskinesia, presenting with or without epilepsy (PNKD3). However, the relevance of KCNMA1 mutations and the basis for clinical heterogeneity in PNKD3 has not been established. Here we evaluate the relative severity of three KCNMA1 patient variants in BK channels, neurons, and mice. In heterologous cells, BKN999S and BKD434G channels displayed gain-of-function (GOF) properties, whereas BKH444Q channels showed loss-of-function (LOF) properties. The relative degree of channel activity was BKN999S > BKD434G > WT > BKH444Q. BK currents and action potential firing were increased, and seizure thresholds decreased, in Kcnma1N999S/WT and Kcnma1D434G/WT transgenic mice but not Kcnma1H444Q/WT mice. In a novel behavioral test for paroxysmal dyskinesia, the more severely affected Kcnma1N999S/WT mice became immobile after stress, consistent with stress-induced immobility episodes observed in PNKD3 patients. Homozygous Kcnma1D434G/D434G mice showed similar immobility, but in contrast, homozygous Kcnma1H444Q/H444Q mice displayed hyperkinetic behavior. These data establish the relative pathogenic potential of patient alleles as N999S > D434G > H444Q and validate Kcnma1N999S/WT mice as a model for PNKD3 with increased seizure propensity.

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“…5 F, G). Knockout of Kcnma1 leads to autophagic dysfunction [ 44 ]. Therefore, these findings suggest that Mef2d mediates VSMC autophagy by regulating the cGMP-PKG signalling pathway.…”

Section: Discussionmentioning

confidence: 99%

Extracellular vesicle miR-32 derived from macrophage promotes arterial calcification in mice with type 2 diabetes via inhibiting VSMC autophagy

Cao

Chen

et al. 2022

J Transl Med

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Background The development of diabetes vascular calcification (VC) is tightly associated with the inhibition of vascular smooth muscle cell (VSMC) autophagy. Previously, our team found that miR-32-5p (miR-32) promotes macrophage activation, and miR-32 is expressed at higher level in the plasma of patients with coronary calcification. However, whether miR-32 mediates the function of macrophages in type 2 diabetes (T2D) VC is still unclear. Methods Wild-type (WT) and miR-32−/− mice were used in this study. qRT-PCR and western blotting were used to analyze gene expression. Flow cytometry was used to analyze the influence of glucose concentration on macrophage polarization. Nanoparticle tracking analysis (NTA), transmission electron microscopy, and confocal microscopy were used to identify macrophage extracellular vehicles (EVs). Immunofluorescence, in situ hybridization (ISH), immunohistochemistry, and alizarin red staining were used to analyze the influence of macrophage EVs on autophagy and calcification of the aorta of miR-32−/− mice. A luciferase assay was used to analyze the effect of miR-32 on myocyte enhancer factor 2D (Mef2d) expression. Co-IP combined with mass spectrometry (MS) and transcriptome sequencing was used to analyze the signalling pathway by which Mef2d acts in VSMC autophagy. Results We found that high glucose conditions upregulate miR-32 expression in macrophages and their EVs. Importantly, macrophages and their EVs promote VSMC osteogenic differentiation and upregulate miR-32 expression in VSMCs. Moreover, miR-32 mimics transfection promoted osteogenic differentiation and inhibited autophagy in VSMCs. In vitro and in vivo experiments showed that Mef2d is the key target gene of miR-32 that inhibits VSMC autophagy. Furthermore, MS and transcriptome sequencing found that cGMP-PKG is an important signalling pathway by which Mef2d regulates VSMC autophagy. In addition, after T2D miR-32−/− mice were injected with macrophage EVs via the caudal vein, miR-32 was detected in aortic VSMCs of miR-32−/− mice. Moreover, autophagy was significantly inhibited, and calcification was significantly enhanced in aorta cells. Conclusions These results reveal that EVs are the key pathway by which macrophages promote T2D VC, and that EVs miR-32 is a key cause of autophagy inhibition in VSMCs.

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Molecular Mechanisms of Epileptic Encephalopathy Caused by KCNMA1 Loss-of-Function Mutations

Cited by 14 publications

References 48 publications

Identification and functional analysis of two new de novo KCNMA1 variants associated with Liang–Wang syndrome

Identification and functional analysis of two new de novo KCNMA1 variants associated with Liang–Wang syndrome

BK channel properties correlate with neurobehavioral severity in three KCNMA1-linked channelopathy mouse models

Extracellular vesicle miR-32 derived from macrophage promotes arterial calcification in mice with type 2 diabetes via inhibiting VSMC autophagy

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