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Hsieh CH, Chou CC, Fang YC, Hsu PH, Chiu YH, Yang CS, Jow GM, Tang CY, Jeng CJ. 14-3-3 proteins regulate cullin 7-mediated Eag1 degradation. Cell Biosci 2023; 13:18. [PMID: 36717938 PMCID: PMC9885684 DOI: 10.1186/s13578-023-00969-w] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2022] [Accepted: 01/23/2023] [Indexed: 01/31/2023] Open
Abstract
BACKGROUND Mutations in the human gene encoding the neuron-specific Eag1 (KV10.1; KCNH1) potassium channel are linked to congenital neurodevelopmental diseases. Disease-causing mutant Eag1 channels manifest aberrant gating function and defective protein homeostasis. Both the E3 ubiquitin ligase cullin 7 (Cul7) and the small acid protein 14-3-3 serve as binding partners of Eag1. Cul7 mediates proteasomal and lysosomal degradation of Eag1 protein, whereas over-expression of 14-3-3 notably reduces Eag1 channel activity. It remains unclear whether 14-3-3 may also contribute to Eag1 protein homeostasis. RESULTS In human cell line and native rat neurons, disruptions of endogenous 14-3-3 function with the peptide inhibitor difopein or specific RNA interference up-regulated Eag1 protein level in a transcription-independent manner. Difopein hindered Eag1 protein ubiquitination at the endoplasmic reticulum and the plasma membrane, effectively promoting the stability of both immature and mature Eag1 proteins. Suppression of endogenous 14-3-3 function also reduced excitotoxicity-associated Eag1 degradation in neurons. Difopein diminished Cul7-mediated Eag1 degradation, and Cul7 knock-down abolished the effect of difopein on Eag1. Inhibition of endogenous 14-3-3 function substantially perturbed the interaction of Eag1 with Cul7. Further structural analyses suggested that the intracellular Per-Arnt-Sim (PAS) domain and cyclic nucleotide-binding homology domain (CNBHD) of Eag1 are essential for the regulatory effect of 14-3-3 proteins. Significantly, suppression of endogenous 14-3-3 function reduced Cul7-mediated degradation of disease-associated Eag1 mutant proteins. CONCLUSION Overall these results highlight a chaperone-like role of endogenous 14-3-3 proteins in regulating Eag1 protein homeostasis, as well as a therapeutic potential of 14-3-3 modulators in correcting defective protein expression of disease-causing Eag1 mutants.
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Affiliation(s)
- Chang-Heng Hsieh
- grid.260539.b0000 0001 2059 7017Institute of Anatomy and Cell Biology, College of Medicine, National Yang Ming Chiao Tung University, Taipei, 112 Taiwan
| | - Chia-Cheng Chou
- grid.36020.370000 0000 8889 3720National Laboratory Animal Center, National Applied Research Laboratories, Taipei, Taiwan
| | - Ya-Ching Fang
- grid.260539.b0000 0001 2059 7017Institute of Anatomy and Cell Biology, College of Medicine, National Yang Ming Chiao Tung University, Taipei, 112 Taiwan ,grid.19188.390000 0004 0546 0241Department of Physiology, College of Medicine, National Taiwan University, Taipei, 100 Taiwan
| | - Po-Hao Hsu
- grid.260539.b0000 0001 2059 7017Institute of Anatomy and Cell Biology, College of Medicine, National Yang Ming Chiao Tung University, Taipei, 112 Taiwan ,grid.19188.390000 0004 0546 0241Department of Physiology, College of Medicine, National Taiwan University, Taipei, 100 Taiwan
| | - Yi-Hung Chiu
- grid.260539.b0000 0001 2059 7017Institute of Anatomy and Cell Biology, College of Medicine, National Yang Ming Chiao Tung University, Taipei, 112 Taiwan
| | - Chi-Sheng Yang
- grid.260539.b0000 0001 2059 7017Institute of Anatomy and Cell Biology, College of Medicine, National Yang Ming Chiao Tung University, Taipei, 112 Taiwan
| | - Guey-Mei Jow
- grid.256105.50000 0004 1937 1063School of Medicine, Fu-Jen Catholic University, New Taipei City, Taiwan
| | - Chih-Yung Tang
- grid.19188.390000 0004 0546 0241Department of Physiology, College of Medicine, National Taiwan University, Taipei, 100 Taiwan
| | - Chung-Jiuan Jeng
- grid.260539.b0000 0001 2059 7017Institute of Anatomy and Cell Biology, College of Medicine, National Yang Ming Chiao Tung University, Taipei, 112 Taiwan ,grid.260539.b0000 0001 2059 7017Brain Research Center, National Yang Ming Chiao Tung University, Taipei, Taiwan
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Cheng P, Qiu Z, Du Y. Potassium channels and autism spectrum disorder: An overview. Int J Dev Neurosci 2021; 81:479-491. [PMID: 34008235 DOI: 10.1002/jdn.10123] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/25/2021] [Revised: 05/08/2021] [Accepted: 05/11/2021] [Indexed: 11/07/2022] Open
Abstract
Autism spectrum disorder (ASD) comprises a group of neurodevelopmental disorders characterized by impaired social interaction and communication, and restricted, repetitive patterns of behaviors, interests, or activities. It had been demonstrated that potassium channels played a key role in regulating neuronal excitability, which was closely associated with neurological diseases including epilepsy, ataxia, myoclonus, and psychiatric disorders. In recent years, a growing body of evidence from whole-genome sequencing and whole-exome sequencing had identified several ASD susceptibility genes of potassium channels in ASD subjects. Genetically dysfunction of potassium channels may be involved in altered neuronal excitability and abnormal brain function in the pathogenesis of ASD. This review summarizes current findings on the features of ASD-risk genes (KCND2, KCNQ2, KCNQ3, KCNH5, KCNJ2, KCNJ10, and KCNMA1) and further expatiate their potential role in the pathogenicity of ASD.
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Affiliation(s)
- Peipei Cheng
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
| | - Zilong Qiu
- Institute of Neuroscience, State Key Laboratory of Neuroscience, Key Laboratory of Primate Neurobiology, Center for Excellence in Brain Science and Intelligence Technology, Chinese Academy of Sciences, Shanghai, China.,Shanghai Center for Brain Science and Brain-Inspired Intelligence Technology, Shanghai, China
| | - Yasong Du
- Shanghai Mental Health Center, Shanghai Jiao Tong University School of Medicine, Shanghai, China
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RPS23RG1 Is Required for Synaptic Integrity and Rescues Alzheimer's Disease-Associated Cognitive Deficits. Biol Psychiatry 2019; 86:171-184. [PMID: 30292394 PMCID: PMC6389446 DOI: 10.1016/j.biopsych.2018.08.009] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/19/2018] [Revised: 08/09/2018] [Accepted: 08/15/2018] [Indexed: 11/22/2022]
Abstract
BACKGROUND Although synaptic impairment is a prerequisite to cognitive deficiencies in Alzheimer's disease (AD), mechanisms underlying the dysregulation of essential synaptic scaffolding components and their integrity remain elusive. RPS23RG1 is a newly identified protein implicated in AD. However, the physiological function of RPS23RG1 has yet to be determined. METHODS We investigated the role of RPS23RG1 in maintaining synaptic structure and function in cell cultures and in Rps23rg1 knockout mice and determined whether targeting RPS23RG1-mediated pathways has therapeutic potential in APP/PS1 AD model mice. RESULTS Deletion of the Rps23rg1 gene resulted in severe memory deficits and impairment of postsynaptic structure and function, with marked reductions in postsynaptic densities-93 and -95 (PSD-93 and PSD-95) levels. RPS23RG1 interacted with PSD-93/PSD-95 through its intracellular domain, consequently sequestering PSD-93/PSD-95 from murine double minute 2-mediated ubiquitination and degradation, thereby maintaining synaptic function. Restoration of PSD-93/PS-D95 levels reversed synaptic and memory deficits in Rps23rg1 knockout mice. We further observed attenuated RPS23RG1 expression in human AD, which positively correlated with PSD-93/PSD-95 levels. Importantly, an RPS23RG1-derived peptide comprising a unique PSD-93/PSD-95 interaction motif rescued synaptic and cognitive defects in Rps23rg1 knockout and AD mouse models. CONCLUSIONS Our results reveal a role for RPS23RG1 in maintaining synaptic integrity and function and provide a new mechanism for synaptic dysfunction in AD pathogenesis. This demonstrates that RPS23RG1-mediated pathways show good therapeutic potential in AD intervention.
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Cullin 7 mediates proteasomal and lysosomal degradations of rat Eag1 potassium channels. Sci Rep 2017; 7:40825. [PMID: 28098200 PMCID: PMC5241692 DOI: 10.1038/srep40825] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2016] [Accepted: 12/12/2016] [Indexed: 11/08/2022] Open
Abstract
Mammalian Eag1 (Kv10.1) potassium (K+) channels are widely expressed in the brain. Several mutations in the gene encoding human Eag1 K+ channel have been associated with congenital neurodevelopmental anomalies. Currently very little is known about the molecules mediating protein synthesis and degradation of Eag1 channels. Herein we aim to ascertain the protein degradation mechanism of rat Eag1 (rEag1). We identified cullin 7 (Cul7), a member of the cullin-based E3 ubiquitin ligase family, as a novel rEag1 binding partner. Immunoprecipitation analyses confirmed the interaction between Cul7 and rEag1 in heterologous cells and neuronal tissues. Cul7 and rEag1 also exhibited significant co-localization at synaptic regions in neurons. Over-expression of Cul7 led to reduced protein level, enhanced ubiquitination, accelerated protein turn-over, and decreased current density of rEag1 channels. We provided further biochemical and morphological evidence suggesting that Cul7 targeted endoplasmic reticulum (ER)- and plasma membrane-localized rEag1 to the proteasome and the lysosome, respectively, for protein degradation. Cul7 also contributed to protein degradation of a disease-associated rEag1 mutant. Together, these results indicate that Cul7 mediates both proteasomal and lysosomal degradations of rEag1. Our findings provide a novel insight to the mechanisms underlying ER and peripheral protein quality controls of Eag1 channels.
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Lörinczi E, Helliwell M, Finch A, Stansfeld PJ, Davies NW, Mahaut-Smith M, Muskett FW, Mitcheson JS. Calmodulin Regulates Human Ether à Go-Go 1 (hEAG1) Potassium Channels through Interactions of the Eag Domain with the Cyclic Nucleotide Binding Homology Domain. J Biol Chem 2016; 291:17907-18. [PMID: 27325704 PMCID: PMC5016179 DOI: 10.1074/jbc.m116.733576] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2016] [Indexed: 11/24/2022] Open
Abstract
The ether à go-go family of voltage-gated potassium channels is structurally distinct. The N terminus contains an eag domain (eagD) that contains a Per-Arnt-Sim (PAS) domain that is preceded by a conserved sequence of 25–27 amino acids known as the PAS-cap. The C terminus contains a region with homology to cyclic nucleotide binding domains (cNBHD), which is directly linked to the channel pore. The human EAG1 (hEAG1) channel is remarkably sensitive to inhibition by intracellular calcium (Ca2+i) through binding of Ca2+-calmodulin to three sites adjacent to the eagD and cNBHD. Here, we show that the eagD and cNBHD interact to modulate Ca2+-calmodulin as well as voltage-dependent gating. Sustained elevation of Ca2+i resulted in an initial profound inhibition of hEAG1 currents, which was followed by a phase when current amplitudes partially recovered, but activation gating was slowed and shifted to depolarized potentials. Deletion of either the eagD or cNBHD abolished the inhibition by Ca2+i. However, deletion of just the PAS-cap resulted in a >15-fold potentiation in response to elevated Ca2+i. Mutations of residues at the interface between the eagD and cNBHD have been linked to human cancer. Glu-600 on the cNBHD, when substituted with residues with a larger volume, resulted in hEAG1 currents that were profoundly potentiated by Ca2+i in a manner similar to the ΔPAS-cap mutant. These findings provide the first evidence that eagD and cNBHD interactions are regulating Ca2+-dependent gating and indicate that the binding of the PAS-cap with the cNBHD is required for the closure of the channels upon CaM binding.
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Affiliation(s)
- Eva Lörinczi
- From the Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 9HN
| | - Matthew Helliwell
- From the Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 9HN, the School of Physiology and Pharmacology, University of Bristol, Bristol BS5 1TD, and
| | - Alina Finch
- From the Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 9HN
| | - Phillip J Stansfeld
- the Department of Biochemistry, University of Oxford, Oxford OX1 3QU, United Kingdom
| | - Noel W Davies
- From the Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 9HN
| | - Martyn Mahaut-Smith
- From the Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 9HN
| | - Frederick W Muskett
- From the Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 9HN
| | - John S Mitcheson
- From the Department of Molecular and Cell Biology, University of Leicester, Leicester LE1 9HN,
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Hsu PH, Chiu YC, Lin TF, Jeng CJ. Ca(2+)-binding protein centrin 4 is a novel binding partner of rat Eag1 K(+) channels. FEBS Open Bio 2016; 6:349-57. [PMID: 27239447 PMCID: PMC4821352 DOI: 10.1002/2211-5463.12045] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/25/2015] [Revised: 02/14/2016] [Accepted: 02/16/2016] [Indexed: 01/14/2023] Open
Abstract
Eag1 is neuron-specific K(+) channel abundantly expressed in the brain and retina. Subcellular localization and physiological analyses in neurons reveal that Eag1 may participate in Ca(2+)-signaling processes in the synapse. Here, we searched for rat Eag1 (rEag1)-binding proteins that may contribute to Ca(2+) regulation of the K(+) channel. Yeast two-hybrid screening identified centrin 4, a member of the centrin family of Ca(2+)-binding proteins. GST pull-down and immunoprecipitation assays in brain and retina lysates confirm the interaction of centrin with rEag1 in neurons. Centrin 4 binds to rEag1 in the absence of Ca(2+). Raising Ca(2+) concentration enhances the association efficiency of centrin 4 and rEag1, and is required for the suppression of rEag1 currents by centrin 4. Altogether, our data suggest that centrin 4 is a novel binding partner that may contribute to Ca(2+) regulation of rEag1 in neurons.
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Affiliation(s)
- Po-Hao Hsu
- Institute of Anatomy and Cell Biology School of Medicine National Yang-Ming University Taipei Taiwan
| | - Yi-Chih Chiu
- Institute of Anatomy and Cell Biology School of Medicine National Yang-Ming University Taipei Taiwan
| | - Ting-Feng Lin
- Institute of Anatomy and Cell Biology School of Medicine National Yang-Ming University Taipei Taiwan
| | - Chung-Jiuan Jeng
- Institute of Anatomy and Cell Biology School of Medicine National Yang-Ming University Taipei Taiwan; Brain Research Center National Yang-Ming University Taipei Taiwan
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Mortensen LS, Schmidt H, Farsi Z, Barrantes-Freer A, Rubio ME, Ufartes R, Eilers J, Sakaba T, Stühmer W, Pardo LA. KV 10.1 opposes activity-dependent increase in Ca²⁺ influx into the presynaptic terminal of the parallel fibre-Purkinje cell synapse. J Physiol 2014; 593:181-96. [PMID: 25556795 DOI: 10.1113/jphysiol.2014.281600] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2014] [Accepted: 10/13/2014] [Indexed: 12/14/2022] Open
Abstract
KEY POINTS Voltage-gated KV 10.1 potassium channels are widely expressed in the mammalian brain but their function remains poorly understood. We report that KV 10.1 is enriched in the presynaptic terminals and does not take part in somatic action potentials. In parallel fibre synapses in the cerebellar cortex, we find that KV 10.1 regulates Ca(2+) influx and neurotransmitter release during repetitive high-frequency activity. Our results describe the physiological role of mammalian KV 10.1 for the first time and help understand the fine-tuning of synaptic transmission. The voltage-gated potassium channel KV 10.1 (Eag1) is widely expressed in the mammalian brain, but its physiological function is not yet understood. Previous studies revealed highest expression levels in hippocampus and cerebellum and suggested a synaptic localization of the channel. The distinct activation kinetics of KV 10.1 indicate a role during repetitive activity of the cell. Here, we confirm the synaptic localization of KV 10.1 both biochemically and functionally and that the channel is sufficiently fast at physiological temperature to take part in repolarization of the action potential (AP). We studied the role of the channel in cerebellar physiology using patch clamp and two-photon Ca(2+) imaging in KV 10.1-deficient and wild-type mice. The excitability and action potential waveform recorded at granule cell somata was unchanged, while Ca(2+) influx into axonal boutons was enhanced in mutants in response to stimulation with three APs, but not after a single AP. Furthermore, mutants exhibited a frequency-dependent increase in facilitation at the parallel fibre-Purkinje cell synapse at high firing rates. We propose that KV 10.1 acts as a modulator of local AP shape specifically during high-frequency burst firing when other potassium channels suffer cumulative inactivation.
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Affiliation(s)
- Lena Sünke Mortensen
- Max-Planck-Institute of Experimental Medicine, 37075, Göttingen, Germany; International Max Planck Research School Neurosciences, 37077, Göttingen, Germany
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Lin TF, Lin IW, Chen SC, Wu HH, Yang CS, Fang HY, Chiu MM, Jeng CJ. The subfamily-specific assembly of Eag and Erg K+ channels is determined by both the amino and the carboxyl recognition domains. J Biol Chem 2014; 289:22815-22834. [PMID: 25008323 DOI: 10.1074/jbc.m114.574814] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
A functional voltage-gated K(+) (Kv) channel comprises four pore-forming α-subunits, and only members of the same Kv channel subfamily may co-assemble to form heterotetramers. The ether-à-go-go family of Kv channels (KCNH) encompasses three distinct subfamilies: Eag (Kv10), Erg (Kv11), and Elk (Kv12). Members of different ether-à-go-go subfamilies, such as Eag and Erg, fail to form heterotetramers. Although a short stretch of amino acid sequences in the distal C-terminal section has been implicated in subfamily-specific subunit assembly, it remains unclear whether this region serves as the sole and/or principal subfamily recognition domain for Eag and Erg. Here we aim to ascertain the structural basis underlying the subfamily specificity of ether-à-go-go channels by generating various chimeric constructs between rat Eag1 and human Erg subunits. Biochemical and electrophysiological characterizations of the subunit interaction properties of a series of different chimeric and truncation constructs over the C terminus suggested that the putative C-terminal recognition domain is dispensable for subfamily-specific assembly. Further chimeric analyses over the N terminus revealed that the N-terminal region may also harbor a subfamily recognition domain. Importantly, exchanging either the N-terminal or the C-terminal domain alone led to a virtual loss of the intersubfamily assembly boundary. By contrast, simultaneously swapping both recognition domains resulted in a reversal of subfamily specificity. Our observations are consistent with the notion that both the N-terminal and the C-terminal recognition domains are required to sustain the subfamily-specific assembly of rat Eag1 and human Erg.
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Affiliation(s)
- Ting-Feng Lin
- Institute of Anatomy and Cell Biology, School of Medicine, and National Yang-Ming University, No. 155, Section 2, Li-Non Street, Taipei 12212, Taiwan
| | - I-Wen Lin
- Institute of Anatomy and Cell Biology, School of Medicine, and National Yang-Ming University, No. 155, Section 2, Li-Non Street, Taipei 12212, Taiwan
| | - Shu-Ching Chen
- Department of Medical Research, National Taiwan University Hospital, Taipei 10051, Taiwan
| | - Hao-Han Wu
- Institute of Anatomy and Cell Biology, School of Medicine, and National Yang-Ming University, No. 155, Section 2, Li-Non Street, Taipei 12212, Taiwan
| | - Chi-Sheng Yang
- Institute of Anatomy and Cell Biology, School of Medicine, and National Yang-Ming University, No. 155, Section 2, Li-Non Street, Taipei 12212, Taiwan
| | - Hsin-Yu Fang
- Institute of Anatomy and Cell Biology, School of Medicine, and National Yang-Ming University, No. 155, Section 2, Li-Non Street, Taipei 12212, Taiwan
| | - Mei-Miao Chiu
- Institute of Anatomy and Cell Biology, School of Medicine, and National Yang-Ming University, No. 155, Section 2, Li-Non Street, Taipei 12212, Taiwan
| | - Chung-Jiuan Jeng
- Institute of Anatomy and Cell Biology, School of Medicine, and National Yang-Ming University, No. 155, Section 2, Li-Non Street, Taipei 12212, Taiwan; Brain Research Center, National Yang-Ming University, No. 155, Section 2, Li-Non Street, Taipei 12212, Taiwan and.
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