Floxed allele for conditional inactivation of the voltage‐gated sodium channel β1 subunit <i>Scn1b</i>

Chen, Chunling; Dickendesher, Travis L.; Oyama, Fumitaka; Miyazaki, Haruko; Nukina, Nobuyuki; Isom, Lori L.

doi:10.1002/dvg.20324

Cited by 10 publications

(17 citation statements)

References 39 publications

(29 reference statements)

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“…The specificity of the anti-β1 intra has been reported previously using Western blot analysis of Scn1b +/+ and Scn1b −/− brain membranes (Chen et al, 2007). To test the specificity of anti-β1 intra using immunofluorescence, we labeled Scn1b +/+ and Scn1b −/− optic nerve nodes of Ranvier as in (Chen et al, 2004) (Supplemental Figure 1, A and B).…”

Section: Methodssupporting

confidence: 63%

“…Primary antibodies used in these studies were: anti-β1 intra (1:1000 dilution) (Oyama et al, 2006; Chen et al, 2007), anti-V5 monoclonal antibody (1:2000, AbD Serotec, Raleigh, NC), or anti-α-tubulin monoclonal antibody (1:10000, Cedarlane Laboratories, Burlington, NC). The specificity of the anti-β1 intra has been reported previously using Western blot analysis of Scn1b +/+ and Scn1b −/− brain membranes (Chen et al, 2007).…”

Section: Methodsmentioning

confidence: 99%

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A Functional Null Mutation ofSCN1Bin a Patient with Dravet Syndrome

et al. 2009

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Dravet syndrome (also called severe myoclonic epilepsy of infancy) is one of the most severe forms of childhood epilepsy. Most patients have heterozygous mutations in SCN1A, encoding voltage-gated sodium channel Na v 1.1 ␣ subunits. Sodium channels are modulated by ␤1 subunits, encoded by SCN1B, a gene also linked to epilepsy. Here we report the first patient with Dravet syndrome associated with a recessive mutation in SCN1B (p.R125C). Biochemical characterization of p.R125C in a heterologous system demonstrated little to no cell surface expression despite normal total cellular expression. This occurred regardless of coexpression of Na v 1.1 ␣ subunits. Because the patient was homozygous for the mutation, these data suggest a functional SCN1B null phenotype. To understand the consequences of the lack of ␤1 cell surface expression in vivo, hippocampal slice recordings were performed in Scn1b Ϫ/Ϫ versus Scn1b ϩ/ϩ mice. Scn1b Ϫ/Ϫ CA3 neurons fired evoked action potentials with a significantly higher peak voltage and significantly greater amplitude compared with wild type. However, in contrast to the Scn1a ϩ/Ϫ model of Dravet syndrome, we found no measurable differences in sodium current density in acutely dissociated CA3 hippocampal neurons. Whereas Scn1b Ϫ/Ϫ mice seize spontaneously, the seizure susceptibility of Scn1b ϩ/Ϫ mice was similar to wild type, suggesting that, like the parents of this patient, one functional SCN1B allele is sufficient for normal control of electrical excitability. We conclude that SCN1B p.R125C is an autosomal recessive cause of Dravet syndrome through functional gene inactivation.

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Section: Methodssupporting

confidence: 63%

Section: Methodsmentioning

confidence: 99%

A Functional Null Mutation ofSCN1Bin a Patient with Dravet Syndrome

et al. 2009

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“…We generated cardiac‐specific Scn1b null mice by first crossing Scn1b flox mice (Chen et al . ) with FLPe transgenic mice to delete the Neo cassette and then crossed these progeny with the B6.FVB‐Tg(Myh6‐cre)2182Mds/J line, which expresses Cre recombinase under the transcriptional control of the α‐myosin heavy chain promoter, (Jackson Laboratories). Following intercrossing of B6.FVB‐Tg(Myh6‐cre)2182Mds/J with Scn1b flox/flox mice, excision of exon 2 occurred selectively in the heart, effectively deleting Scn1b (Fig.…”

Section: Resultsmentioning

confidence: 99%

“…Scn1b flox/flox mice were described previously (Chen et al . ). Despite the earlier observation that these mice, with the neo cassette from the targeting vector intact, lived normal life spans and did not seize, we elected to cross them with FLPe transgenic mice (Jackson Laboratories, B6;SJL‐Tg(ACTFLPe)9205Dym/J; Rodriguez et al .…”

Section: Methodsmentioning

confidence: 97%

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Scn1b deletion leads to increased tetrodotoxin‐sensitive sodium current, altered intracellular calcium homeostasis and arrhythmias in murine hearts

Lin

O’Malley

Chen

et al. 2014

The Journal of Physiology

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Key pointsr Na + current (I Na ) results from the integrated function of a molecular aggregate (the voltage-gated Na + channel complex) that includes the β subunit family. r We propose that life-threatening arrhythmias in patients with mutations in Scn1b, a gene classically defined as ancillary to the Na + channel α subunit, can be partly consequent to disrupted intracellular Ca 2+ homeostasis.Abstract Na + current (I Na ) is determined not only by the properties of the pore-forming voltage-gated Na + channel (VGSC) α subunit, but also by the integrated function of a molecular aggregate (the VGSC complex) that includes the VGSC β subunit family. Mutations or rare variants in Scn1b (encoding the β1 and β1B subunits) have been associated with various inherited arrhythmogenic syndromes, including cases of Brugada syndrome and sudden unexpected death in patients with epilepsy. Here, we have used Scn1b null mouse models to understand better the relation between Scn1b expression, and cardiac electrical function. Using a combination of macropatch and scanning ion conductance microscopy we show that loss of Scn1b in juvenile null animals resulted in increased tetrodotoxin-sensitive I Na but only in the cell midsection, even before full T-tubule formation; the latter occurred concurrent with increased message abundance for the neuronal Scn3a mRNA, suggesting increased abundance of tetrodotoxin-sensitive Na V 1.3 protein and yet its exclusion from the region of the intercalated disc. Ventricular myocytes from cardiac-specific adult Scn1b null animals showed increased Scn3a message, prolonged action potential repolarization, presence of delayed after-depolarizations and triggered beats, delayed Ca 2+ transients and frequent spontaneous Ca 2+ release events and at the whole heart level, increased susceptibility to polymorphic ventricular arrhythmias. Most alterations in Ca homeostasis were prevented by 100 nM tetrodotoxin. Our results suggest that life-threatening arrhythmias in patients with mutations in Scn1b, a gene classically defined as ancillary to the Na + channel α subunit, can be partly consequent to disrupted intracellular Ca 2+ homeostasis in ventricular myocytes.

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Excitatory and inhibitory neuron defects in a mouse model of Scn1b‐linked EIEE52

Hull

O’Malley²,

Chen

et al. 2020

Ann Clin Transl Neurol

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Objective: Human variants in voltage-gated sodium channel (VGSC) α and β subunit genes are linked to developmental and epileptic encephalopathies (DEEs). Inherited, biallelic, loss-of-function variants in SCN1B, encoding the β1/β1B subunits, are linked to early infantile DEE (EIEE52). De novo, monoallelic variants in SCN1A (Nav1.1), SCN2A (Nav1.2), SCN3A (Nav1.3), and SCN8A (Nav1.6) are also linked to DEEs. While these VGSC-linked DEEs have similar presentations, they have diverse mechanisms of altered neuronal excitability. Mouse models have suggested that Scn2a-, Scn3a-, and Scn8a-linked DEE variants are, in general, gain of function, resulting in increased persistent or resurgent sodium current (I Na) and pyramidal neuron hyperexcitability. In contrast, Scn1a-linked DEE variants, in general, are loss-of-function, resulting in decreased I Na and hypoexcitability of fast-spiking interneurons. VGSC β1 subunits associate with Nav1.1, Nav1.2, Nav1.3, and Nav1.6 and are expressed throughout the brain, raising the possibility that insults to both pyramidal and interneuron excitability may drive EIEE52 pathophysiology. Methods: We investigated excitability defects in pyramidal and parvalbumin-positive (PV +) interneurons in the Scn1b −/− model of EIEE52. We also used Scn1b FL/FL mice to delete Scn1b in specific neuronal populations. Results: Scn1b −/− cortical PV + interneurons were hypoexcitable, with reduced I Na density. Scn1b −/− cortical pyramidal neurons had population-specific changes in excitability and impaired I Na density. Scn1b deletion in PV + neurons resulted in 100% lethality, whereas deletion in Emx1 + or Camk2a + neurons did not affect survival. Interpretation: This work suggests that SCN1B-linked DEE variants impact both excitatory and inhibitory neurons, leading to the increased severity of EIEE52 relative to other DEEs.

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Floxed allele for conditional inactivation of the voltage‐gated sodium channel β1 subunit Scn1b

Cited by 10 publications

References 39 publications

A Functional Null Mutation ofSCN1Bin a Patient with Dravet Syndrome

A Functional Null Mutation ofSCN1Bin a Patient with Dravet Syndrome

Scn1b deletion leads to increased tetrodotoxin‐sensitive sodium current, altered intracellular calcium homeostasis and arrhythmias in murine hearts

Excitatory and inhibitory neuron defects in a mouse model of Scn1b‐linked EIEE52

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