PUBLICATION
Cloning and expression of a zebrafish SCN1B ortholog and identification of a species-specific splice variant
- Authors
- Fein, A.J., Meadows, L.S., Chen, C., Slat, E.A., and Isom, L.L.
- ID
- ZDB-PUB-070726-4
- Date
- 2007
- Source
- BMC Genomics 8(1): 226 (Journal)
- Registered Authors
- Keywords
- none
- MeSH Terms
-
- Alternative Splicing
- Amino Acid Sequence
- Animals
- Antibodies/chemistry
- Antibodies/pharmacology
- Base Sequence
- Cells, Cultured
- Cloning, Molecular
- Cricetinae
- Cricetulus
- Electrophysiology
- Embryo, Nonmammalian
- Gene Expression Regulation, Developmental*
- Models, Molecular
- Molecular Sequence Data
- Protein Isoforms/genetics
- Rats
- Sequence Homology, Amino Acid
- Sodium Channels/genetics*
- Sodium Channels/immunology
- Sodium Channels/metabolism
- Sodium Channels/physiology
- Species Specificity
- Tissue Distribution
- Voltage-Gated Sodium Channel beta-1 Subunit
- Xenopus laevis
- Zebrafish/embryology
- Zebrafish/genetics*
- Zebrafish Proteins/genetics*
- Zebrafish Proteins/immunology
- Zebrafish Proteins/metabolism
- PubMed
- 17623064 Full text @ BMC Genomics
Citation
Fein, A.J., Meadows, L.S., Chen, C., Slat, E.A., and Isom, L.L. (2007) Cloning and expression of a zebrafish SCN1B ortholog and identification of a species-specific splice variant. BMC Genomics. 8(1):226.
Abstract
BACKGROUND: Voltage-gated Na+ channel beta 1 (Scn1b) subunits are multi-functional proteins that play roles in current modulation, channel cell surface expression, cell adhesion, cell migration, and neurite outgrowth. We have shown previously that beta 1 modulates electrical excitability in vivo using a mouse model. Scn1b null mice exhibit spontaneous seizures and ataxia, slowed action potential conduction, decreased numbers of nodes of Ranvier in myelinated axons, alterations in nodal architecture, and differences in Na+ channel alpha subunit localization. The early death of these mice at postnatal day 19, however, make them a challenging model system to study. As a first step toward development of an alternative model to investigate the physiological roles of beta 1 subunits in vivo we cloned two beta 1-like subunit cDNAs from D. rerio. RESULTS: Two beta 1-like subunit mRNAs from zebrafish, scn1ba_tv1 and scn1ba_tv2, arise from alternative splicing of scn1ba. The deduced amino acid sequences of Scn1ba_tv1 and Scn1ba_tv2 are identical except for their C-terminal domains. The C-terminus of Scn1ba_tv1 contains a tyrosine residue similar to that found to be critical for ankyrin association and Na+ channel modulation in mammalian beta 1. In contrast, Scn1ba_tv2 contains a unique, species-specific C-terminal domain that does not contain a tyrosine. Immunohistochemical analysis shows that, while the expression patterns of Scn1ba_tv1 and Scn1ba_tv2 overlap in some areas of the brain, retina, spinal cord, and skeletal muscle, only Scn1ba_tv1 is expressed in optic nerve where its staining pattern suggests nodal expression. Both scn1ba splice forms modulate Na+ currents expressed by zebrafish scn8aa, resulting in shifts in channel gating mode, increased current amplitude, negative shifts in the voltage dependence of current activation and inactivation, and increases in the rate of recovery from inactivation, similar to the function of mammalian beta 1 subunits. In contrast to mammalian beta 1, however, neither zebrafish subunit produces a complete shift to the fast gating mode and neither subunit produces complete channel inactivation or recovery from inactivation. CONCLUSIONS: These data add to our understanding of structure-function relationships in Na+ channel beta 1 subunits and establish zebrafish as an ideal system in which to determine the contribution of scn1ba to electrical excitability in vivo.
Genes / Markers
Expression
Phenotype
Mutations / Transgenics
Human Disease / Model
Sequence Targeting Reagents
Fish
Orthology
Engineered Foreign Genes
Mapping