Human skeletal muscle calcium channel α1S is expressed in the basal ganglia: distinctive expression pattern among L-type Ca2+ channels
Introduction
Voltage-gated calcium channels (VGCCs) are essential molecules for excitatory cells, especially for neurons that mediate various important cellular functions. These channels initiate muscle contraction, modulate action potential waveforms, trigger release of neurotransmitters from nerve terminals or hormones from endocrine cells (Perney et al., 1986, Fossier et al., 1999), determine firing patterns and input–output characteristics of various neuronal cells (Llinas, 1988), regulate gene expression and cell cycle (Ramsdell, 1991, Bading et al., 1993, Hardingham et al., 1997), and mediate cell death (Lobner and Lipton, 1993, Porter et al., 1997). VGCCs are clinically important as well, and have been implicated in the pathogenesis of a number of diseases. For example, mutations of VGCCs cause hereditary neurological diseases such as hypokalemic periodic paralysis (Ptacek et al., 1994) and malignant hyperthermia (Monnier et al., 1997), and VGCC antibodies cause Lambert–Eaton myasthenic syndrome (Leys et al., 1989). VGCCs are also the targets for several therapeutic pharmaceuticals, including drugs for hypertension, arrhythmia, angina pectoris, and migraine (Abernethy and Schwartz, 1999).
VGCCs consist of five subunits, α1, α2, β, γ, and δ. Among the subunits, α1 is essential, as it can form a functional Ca2+ channel by itself, and it contains domains of the channel pore and the voltage sensor (Hofmann et al., 1994, Walker and De Waard, 1998). The structure of the α1 subunit consists of four homologous repeats, each with six putative transmembrane segments. The segments consist of highly conserved sequences among all the subtypes, whereas the cytoplasmic loop and the carboxyl terminal region are strikingly different among α1 subtypes.
To date, ten distinct genes encoding VGCC α1 subunit subtypes (α1A-I and S) have been identified. Nervous system expression has been reported for all subtypes except α1S (Snutch et al., 1990). VGCCs are classified, electrophysiologically and pharmacologically, into L-type (α1C, D, F, and S), P/Q-type (α1A), N-type (α1B), R-type (α1E), and T-type (α1G, H, and I). Among L-type calcium channels immunoprecipitated from rat cerebral cortex and the hippocampus, approximately 75% are α1C, and 20% are α1D (Hell et al., 1993). Based on channel currents, the remaining 5% of L-type channels are suspected to contain α1S and/or α1F, although skeletal muscle type α1S, and retinal type α1F, have not been identified in Northern blots from these brain regions (Ellis et al., 1988, Fisher et al., 1997, Strom et al., 1998). In this study, we screened human brain cDNA and found that α1S was also expressed in the central nervous system. We investigated the expression pattern of α1S in comparison with those of other L-type Ca2+ channels, α1C and α1D.
Section snippets
PCR screening
Total RNA from normal human whole brain was extracted and reverse transcribed, and nested PCR was performed using the degenerate primers as described previously (Jeong et al., 2000). We developed the degenerate primers using the consensus sequence of α1 subunit subtypes. The primer sets for α1A-F and S were Ca5, Ca3A, and Ca3B designated as set 1, and for α1G-I, Ca2F, Ca2FC, and Ca2R as set 2. The first PCR conditions were, 95 °C for 2 min, followed by 30 cycles consisting of 95 °C for 15 s, 56 °C
PCR screening and cloning using degenerate primers for VGCCs from human brain cDNA
In order to screen human whole brain cDNA by PCR, we designed two sets of degenerate primers, set 1 for α1A-F and α1S, and set 2 for α1G-I, so as to identify each subtype by its size and restriction enzyme patterns as described in the experimental methods. All eight of the α1 subunits with previously described expression (α1A-E and α1G-I) were obtained by this method. Retina was not included in the human cDNA, thus α1F was not obtained. Unexpectedly, we identified α1S, which was known as
Discussion
Our study revealed that human and rat α1S was also expressed in the nervous system, particularly in the basal ganglia. Three isoforms of α1S, a full-length isoform and two truncated isoforms, have been reported in the skeletal muscle. One truncated form, which was designated as a newborn form, has a deletion of 2047 bp from nucleotide 1431–3478 (Malouf et al., 1992), and contains the sequences for our RT-PCR primers and Northern blotting probes. The expression level of the newborn isoform in
Acknowledgements
This work was supported by grants-in-aid from SORST, Japan Science and Technology and grants-in-aid from Japan Ministry of Health, Labor, and Welfare. The authors thank R.P. Ruberu for technical advice.
References (48)
- et al.
Sequence-based exon prediction around the synaptophysin locus reveals a gene-rich area containing novel genes in human proximal Xp
Genomics
(1997) - et al.
Calcium transients and neurotransmitter release at an identified synapse
Trends Neurosci.
(1999) - et al.
Regulation of ion channels by cAMP-dependent protein kinase and A-kinase anchoring proteins
Curr. Opin. Neurobiol.
(1998) - et al.
Beyond the dopamine receptor: the DARPP-32/protein phosphatase-1 cascade
Neuron
(1999) - et al.
Single cell analysis of CAG repeat in brains of dentatorubral-pallidoluysian atrophy (DRPLA)
J. Neurol. Sci.
(2001) - et al.
Synthetic peptide analogs of DARPP-32 (Mr 32 000 dopamine- and cAMP-regulated phosphoprotein), an inhibitor of protein phosphatase-1. Phosphorylation, dephosphorylation, and inhibitory activity
J. Biol. Chem.
(1990) - et al.
Identification of a novel human voltage-gated sodium channel alpha subunit gene, SCN12A
Biochem. Biophys. Res. Commun.
(2000) - et al.
Calcium channel autoantibodies in Lambert–Eaton myasthenic syndrome
Lancet
(1989) - et al.
Calcium-induced calcium release in cerebellar Purkinje cells
Neuron
(1994) - et al.
A two-motif isoform of the major calcium channel subunit in skeletal muscle
Neuron
(1992)
Malignant-hyperthermia susceptibility is associated with a mutation of the alpha 1-subunit of the human dihydropyridine-sensitive L-type voltage-dependent calcium-channel receptor in skeletal muscle
Am. J. Hum. Genet.
Primary structure and functional expression from cDNA of the cardiac ryanodine receptor/calcium release channel
FEBS Lett.
Molecular cloning of cDNA encoding the Ca2+ release channel (ryanodine receptor) of rabbit cardiac muscle sarcoplasmic reticulum
J. Biol. Chem.
Dihydropyridine receptor mutations cause hypokalemic periodic paralysis
Cell
Localization of a novel ryanodine receptor gene (RYR3) to human chromosome 15q14-q15 by in situ hybridization
Genomics
Modulation of calcium currents by a D1 dopaminergic protein kinase/phosphatase cascade in rat neostriatal neurons
Neuron
Subunit interaction sites in voltage-dependent Ca2+ channels: role in channel function
Trends Neurosci.
Structure and functional expression of alpha 1, alpha 2, and beta subunits of a novel human neuronal calcium channel subtype
Neuron
Molecular cloning of cDNA encoding human and rabbit forms of the Ca2+ release channel (ryanodine receptor) of skeletal muscle sarcoplasmic reticulum
J. Biol. Chem.
Calcium-antagonist drugs
New Engl. J. Med.
Regulation of gene expression in hippocampal neurons by distinct calcium signaling pathways
Science
Phosphorylation of DARPP-32 by Cdk5 modulates dopamine signaling in neurons
Nature
Synaptic and intrinsic control of membrane excitability of neostriatal neurons. I. An in vivo analysis
J. Neurophysiol.
Functional coupling between ryanodine receptors and L-type calcium channels in neurons
Nature
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