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Fox PM, Malepati S, Manaster L, Rossignol E, Noebels JL. Developing a pathway to clinical trials for CACNA1A-related epilepsies: A patient organization perspective. THERAPEUTIC ADVANCES IN RARE DISEASE 2024; 5:26330040241245725. [PMID: 38681799 PMCID: PMC11047245 DOI: 10.1177/26330040241245725] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 12/26/2023] [Accepted: 03/15/2024] [Indexed: 05/01/2024]
Abstract
CACNA1A-related disorders are rare neurodevelopmental disorders linked to variants in the CACNA1A gene. This gene encodes the α1 subunit of the P/Q-type calcium channel Cav2.1, which is globally expressed in the brain and crucial for fast synaptic neurotransmission. The broad spectrum of CACNA1A-related neurological disorders includes developmental and epileptic encephalopathies, familial hemiplegic migraine type 1, episodic ataxia type 2, spinocerebellar ataxia type 6, together with unclassified presentations with developmental delay, ataxia, intellectual disability, autism spectrum disorder, and language impairment. The severity of each disorder is also highly variable. The spectrum of CACNA1A-related seizures is broad across both loss-of-function and gain-of-function variants and includes absence seizures, focal seizures with altered consciousness, generalized tonic-clonic seizures, tonic seizures, status epilepticus, and infantile spasms. Furthermore, over half of CACNA1A-related epilepsies are refractory to current therapies. To date, almost 1700 CACNA1A variants have been reported in ClinVar, with over 400 listed as Pathogenic or Likely Pathogenic, but with limited-to-no clinical or functional data. Robust genotype-phenotype studies and impacts of variants on protein structure and function have also yet to be established. As a result, there are few definitive treatment options for CACNA1A-related epilepsies. The CACNA1A Foundation has set out to change the landscape of available and effective treatments and improve the quality of life for those living with CACNA1A-related disorders, including epilepsy. Established in March 2020, the Foundation has built a robust preclinical toolbox that includes patient-derived induced pluripotent stem cells and novel disease models, launched clinical trial readiness initiatives, and organized a global CACNA1A Research Network. This Research Network is currently composed of over 60 scientists and clinicians committed to collaborating to accelerate the path to CACNA1A-specific treatments and one day, a cure.
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Affiliation(s)
- Pangkong M. Fox
- CACNA1A Foundation, Inc., 31 Pt Road, Norwalk, CT 06854, USA
| | | | | | - Elsa Rossignol
- CACNA1A Foundation, Inc., Norwalk, CT, USA
- CHU Sainte-Justine Research Center, Departments of Neurosciences and Pediatrics, University of Montreal, Montreal, QC, Canada
| | - Jeffrey L. Noebels
- CACNA1A Foundation, Inc., Norwalk, CT, USA
- Blue Bird Circle Developmental Neurogenetics Laboratory, Department of Neurology, Baylor College of Medicine, One Baylor Plaza, Houston, TX, USA
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Perez-Saad H, Subiros N, Berlanga J, Aldana L, Garcia del Barco D. Neuroprotective effect of epidermal growth factor in experimental acrylamide neuropathy: an electrophysiological approach. J Peripher Nerv Syst 2017; 22:106-111. [DOI: 10.1111/jns.12214] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Revised: 04/07/2017] [Accepted: 04/10/2017] [Indexed: 11/26/2022]
Affiliation(s)
- H. Perez-Saad
- Department of Pharmaceuticals, Division of Biomedical Research; Center for Genetic Bioengineering and Biotechnology; Havana Cuba
| | - N. Subiros
- Department of Pharmaceuticals, Division of Biomedical Research; Center for Genetic Bioengineering and Biotechnology; Havana Cuba
| | - J. Berlanga
- Department of Pharmaceuticals, Division of Biomedical Research; Center for Genetic Bioengineering and Biotechnology; Havana Cuba
| | - L. Aldana
- Department of Pharmaceuticals, Division of Biomedical Research; Center for Genetic Bioengineering and Biotechnology; Havana Cuba
| | - D. Garcia del Barco
- Department of Pharmaceuticals, Division of Biomedical Research; Center for Genetic Bioengineering and Biotechnology; Havana Cuba
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Mutation Spectrum in the CACNA1A Gene in 49 Patients with Episodic Ataxia. Sci Rep 2017; 7:2514. [PMID: 28566750 PMCID: PMC5451382 DOI: 10.1038/s41598-017-02554-x] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2015] [Accepted: 04/13/2017] [Indexed: 11/08/2022] Open
Abstract
Episodic ataxia is an autosomal dominant ion channel disorder characterized by episodes of imbalance and incoordination. The disease is genetically heterogeneous and is classified as episodic ataxia type 2 (EA2) when it is caused by a mutation in the CACNA1A gene, encoding the α1A subunit of the P/Q-type voltage-gated calcium channel Cav2.1. The vast majority of EA2 disease-causing variants are loss-of-function (LoF) point changes leading to decreased channel currents. CACNA1A exonic deletions have also been reported in EA2 using quantitative approaches. We performed a mutational screening of the CACNA1A gene, including the promoter and 3'UTR regions, in 49 unrelated patients diagnosed with episodic ataxia. When pathogenic variants were not found by sequencing, we performed a copy number variant (CNV) analysis to screen for duplications or deletions. Overall, sequencing screening allowed identification of six different point variants (three nonsense and three missense changes) and two coding indels, one of them found in two unrelated patients. Additionally, CNV analysis identified a deletion in a patient spanning exon 35 as a result of a recombination event between flanking intronic Alu sequences. This study allowed identification of potentially pathogenic alterations in our sample, five of them novel, which cover 20% of the patients (10/49). Our data suggest that most of these variants are disease-causing, although functional studies are required.
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Kim TY, Niimi K, Takahashi E. Protein expression pattern in cerebellum of Cav2.1 mutant, tottering-6j mice. Exp Anim 2016; 65:207-14. [PMID: 26887908 PMCID: PMC4976234 DOI: 10.1538/expanim.15-0120] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022] Open
Abstract
Neuronal voltage-gated Cav2.1 channel controls a broad array of functions, including neurotransmitter release, neuronal excitability, activity-dependent gene expression, and neuronal survival. The Cav2.1 channel is molecular complexes consisting of several subunits: α1, α2/δ, β, and γ. The pore-forming subunit, α1, is encoded by the Cacna1a gene. Tottering-6j mice, generated by the Neuroscience Mutagenesis Facility at The Jackson Laboratory, are a recessive mutant strain in which the mutation has been chemically induced by ethylnitrosourea. In tottering-6j mice, mutation in the Cacna1a gene results in a base substitution (C-to-A) in the consensus splice acceptor sequence, which results in deletion of a part of the S4-S5 linker, S5, and a part of S5-S6 linker domain I in the α1 subunit of Cav2.1 channel. The mice display motor dysfunctions and absence-like seizures. However, protein expression in the cerebellum of tottering-6j mice has not been investigated. Real-time quantitative reverse transcription polymerase chain reaction and histological analyses of the cerebellum of tottering-6j mice revealed high expression levels of tyrosine hydroxylase, zebrin II, and ryanodine receptor 3 compared with those of wild-type mice. Conversely, a low level of calretinin expression was found compared with wild-type mice. These results indicate that Cacna1a mutation plays a significant role in protein expression patterns and that the tottering-6j mouse is a useful model for understanding protein expression mechanisms.
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Affiliation(s)
- Tae Yeon Kim
- Research Resources Center, RIKEN Brain Science Institute 2-1 Hirosawa, Wako, Saitama 351-0198, Japan
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Zhu JW, Li YF, Wang ZT, Jia WQ, Xu RX. Toll-Like Receptor 4 Deficiency Impairs Motor Coordination. Front Neurosci 2016; 10:33. [PMID: 26909014 PMCID: PMC4754460 DOI: 10.3389/fnins.2016.00033] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/08/2015] [Accepted: 01/27/2016] [Indexed: 11/13/2022] Open
Abstract
The cerebellum plays an essential role in balance and motor coordination. Purkinje cells (PCs) are the sole output neurons of the cerebellar cortex and are critical for the execution of its functions, including motor coordination. Toll-like receptor (TLR) 4 is involved in the innate immune response and is abundantly expressed in the central nervous system; however, little is known about its role in cerebellum-related motor functions. To address this question, we evaluated motor behavior in TLR4 deficient mice. We found that TLR4(-∕-) mice showed impaired motor coordination. Morphological analyses revealed that TLR4 deficiency was associated with a reduction in the thickness of the molecular layer of the cerebellum. TLR4 was highly expressed in PCs but not in Bergmann glia or cerebellar granule cells; however, loss of TLR4 decreased the number of PCs. These findings suggest a novel role for TLR4 in cerebellum-related motor coordination through maintenance of the PC population.
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Affiliation(s)
- Jian-Wei Zhu
- Affiliated Bayi Brain Hospital, Military General Hospital of Beijing PLA, Southern Medical University Beijing, China
| | - Yi-Fei Li
- Affiliated Bayi Brain Hospital, Military General Hospital of Beijing PLA, Southern Medical University Beijing, China
| | - Zhao-Tao Wang
- Affiliated Bayi Brain Hospital, Military General Hospital of Beijing PLA, Southern Medical University Beijing, China
| | - Wei-Qiang Jia
- Affiliated Bayi Brain Hospital, Military General Hospital of Beijing PLA, Southern Medical University Beijing, China
| | - Ru-Xiang Xu
- Affiliated Bayi Brain Hospital, Military General Hospital of Beijing PLA, Southern Medical University Beijing, China
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Kim TY, Maki T, Zhou Y, Sakai K, Mizuno Y, Ishikawa A, Tanaka R, Niimi K, Li W, Nagano N, Takahashi E. Absence-like seizures and their pharmacological profile in tottering-6j mice. Biochem Biophys Res Commun 2015; 463:148-53. [PMID: 26002462 DOI: 10.1016/j.bbrc.2015.05.050] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/30/2015] [Accepted: 05/10/2015] [Indexed: 10/23/2022]
Abstract
We previously showed that recessive ataxic tottering-6j mice carried a base substitution (C-to-A) in the consensus splice acceptor sequence linked to exon 5 of the α1 subunit of the Cav2.1 channel gene (Cacna1a), resulting in the skipping of exon 5 and deletion of part of the S4-S5 linker, S5, and part of the S5-S6 linker in domain I of the α1 subunit of the Cav2.1 channel. However, the electrophysiological and pharmacological consequences of this mutation have not previously been investigated. Upon whole-cell patch recording of the recombinant Cav2.1 channel in heterologous reconstitution expression systems, the mutant-type channel exhibited a lower recovery time after inactivation of Ca(2+) channel current, without any change in peak current density or the current-voltage relationship. Tottering-6j mice exhibited absence-like seizures, characterized by bilateral and synchronous 5-8 Hz spike-and-wave discharges on cortical and hippocampal electroencephalograms, concomitant with sudden immobility and staring. The pharmacological profile of the seizures was similar to that of human absence epilepsy; the seizures were inhibited by ethosuximide and valproic acid, but not by phenytoin. Thus, the tottering-6j mouse is a useful model for studying Cav2.1 channel functions and Cacna1a-related diseases, including absence epilepsy.
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Affiliation(s)
- Tae Yeon Kim
- Research Resources Center, RIKEN Brain Science Institute, Saitama, 351-0198, Japan
| | - Takehiro Maki
- Sleep Science Laboratories, HAMRI Co. Ltd., Ibaraki, 306-0128, Japan
| | - Ying Zhou
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China
| | - Keita Sakai
- Sleep Science Laboratories, HAMRI Co. Ltd., Ibaraki, 306-0128, Japan
| | - Yuri Mizuno
- Sleep Science Laboratories, HAMRI Co. Ltd., Ibaraki, 306-0128, Japan
| | - Akiyoshi Ishikawa
- Sleep Science Laboratories, HAMRI Co. Ltd., Ibaraki, 306-0128, Japan
| | - Ryo Tanaka
- Sleep Science Laboratories, HAMRI Co. Ltd., Ibaraki, 306-0128, Japan
| | - Kimie Niimi
- Research Resources Center, RIKEN Brain Science Institute, Saitama, 351-0198, Japan
| | - Weidong Li
- Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China
| | - Norihiro Nagano
- Sleep Science Laboratories, HAMRI Co. Ltd., Ibaraki, 306-0128, Japan
| | - Eiki Takahashi
- Research Resources Center, RIKEN Brain Science Institute, Saitama, 351-0198, Japan; Bio-X Institutes, Key Laboratory for the Genetics of Developmental and Neuropsychiatric Disorders (Ministry of Education), Shanghai Jiao Tong University, Shanghai, 200240, People's Republic of China.
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Yoshimoto T, Aoyama Y, Kim TY, Niimi K, Takahashi E, Itakura C. Rolling Nagoya mouse strain (PROD-rol/rol) with classic piebald mutation. J Vet Med Sci 2014; 76:1093-8. [PMID: 24758835 PMCID: PMC4155188 DOI: 10.1292/jvms.14-0096] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022] Open
Abstract
Ataxic
rolling Nagoya (PROD-rol/rol) mice,
which carry a mutation in the α1 subunit of the Cav2.1 channel
(Cacna1a) gene, were discovered in 1969. They show white spots on
agouti coat and have a mutation in the piebald spotting (s) locus.
However, mutation analysis of the s locus encoding the endothelin
receptor type B (Ednrb) gene in
PROD-rol/rol mice had not been performed. Here, we
examined the genomic and mRNA sequences of the Ednrb gene in
PROD-rol/rol and wild-type rolling
Nagoya (PROD-s/s) and studied the expression patterns of
Ednrb and Cacna1a genes in these mice in comparison
with C57BL/6J mice. Polymerase chain reaction analyses revealed two silent nucleotide
substitutions in the coding region and insertion of a retroposon-like element in intron 1
of the Ednrb gene. Expression analyses demonstrated similar localizations
and levels of Ednrb and Cacna1a expression in the colon
between PROD-rol/rol and
PROD-s/s mice, but the expression levels of both genes
were diminished compared with C57BL/6J mice. Microsatellite genotyping showed that at
least particular regions of chromosome 14 proximal to the Ednrb locus of
the PROD strain were derived from Japanese fancy piebald mice. These results indicated
that PROD-rol/rol mice have two mutant genes,
Ednrb and Cacna1a. As no PROD strain had an intact
Ednrb gene, using congenic rolling mice would better serve to examine
rolling Nagoya-type Cav2.1 channel dysfunctions.
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Affiliation(s)
- Takuro Yoshimoto
- Research Resources Center, RIKEN Brain Science Institute, Saitama 351-0198, Japan
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Differential neuronal targeting of a new and two known calcium channel β4 subunit splice variants correlates with their regulation of gene expression. J Neurosci 2014; 34:1446-61. [PMID: 24453333 DOI: 10.1523/jneurosci.3935-13.2014] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
The β subunits of voltage-gated calcium channels regulate surface expression and gating of CaV1 and CaV2 α1 subunits and thus contribute to neuronal excitability, neurotransmitter release, and calcium-induced gene regulation. In addition, certain β subunits are targeted into the nucleus, where they interact directly with the epigenetic machinery. Whereas their involvement in this multitude of functions is reflected by a great molecular heterogeneity of β isoforms derived from four genes and abundant alternative splicing, little is known about the roles of individual β variants in specific neuronal functions. In the present study, an alternatively spliced β4 subunit lacking the variable N terminus (β4e) is identified. It is highly expressed in mouse cerebellum and cultured cerebellar granule cells (CGCs) and modulates P/Q-type calcium currents in tsA201 cells and CaV2.1 surface expression in neurons. Compared with the other two known full-length β4 variants (β4a and β4b), β4e is most abundantly expressed in the distal axon, but lacks nuclear-targeting properties. To determine the importance of nuclear targeting of β4 subunits for transcriptional regulation, we performed whole-genome expression profiling of CGCs from lethargic (β4-null) mice individually reconstituted with β4a, β4b, and β4e. Notably, the number of genes regulated by each β4 splice variant correlated with the rank order of their nuclear-targeting properties (β4b > β4a > β4e). Together, these findings support isoform-specific functions of β4 splice variants in neurons, with β4b playing a dual role in channel modulation and gene regulation, whereas the newly detected β4e variant serves exclusively in calcium-channel-dependent functions.
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Impaired motor function in senescence-accelerated mouse prone 1 (SAMP1). Brain Res 2013; 1515:48-54. [PMID: 23583482 DOI: 10.1016/j.brainres.2013.03.053] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Revised: 02/07/2013] [Accepted: 03/31/2013] [Indexed: 01/08/2023]
Abstract
Senescence-accelerated mouse prone (SAMP) strains of mice show early onset of senescence, whereas senescence-accelerated mouse resistant (SAMR) strains are resistant to early senescence and serve as controls. Although SAMP6 and SAMP8 are established models of central nervous system alterations, it is unclear whether SAMP1/Sku (SAMP1) is characterized by brain alterations and dysfunction related to behavioral functioning. In the present study, behavioral tests (i.e., locomotor activity, Y-maze, rotating rod, hind-limb extension, and traction), histochemistry, and Western blot analyses were employed to study this mouse model using 2- and 4-month-old SAMP1 and age-matched control SAMR1. Although 2-month-old SAMP1 and SAMR1 showed similar activity, 4-month-old SAMP1 exhibited less activity than age-matched SAMR1 in locomotor activity and Y-maze tests. In rotating rod test, 2- and 4-month-old SAMP1 showed motor-coordination dysfunction. An abnormal extension reflex in the hind-limb test was observed in 2- and 4-month-old SAMP1. There were no significant differences between SAMP1 and SAMR1 with respect to grip strength in the traction test or alternation behavior in the Y-maze test. Histochemistry and Western blot analyses exhibited that cerebellar Purkinje cells in 4-month-old SAMP1 mice persistently expressed tyrosine hydroxylase. These results suggest that SAMP1 is a useful model for examining mechanisms underlying motor dysfunction.
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