Novel splice variants of the voltage-sensitive sodium channel alpha subunit.
In this study, we have identified novel splice variants of the Na+ channel alpha subunit mRNA from cultured rat astrocytes and neuroblastoma cells. These splice variants are characterized by premature truncation or deletion of a segment in the third domain of the Na+ channel alpha subunit. The expression of three splice variants was upregulated by exposure to 1 mM dibutyryl cAMP in spinal cord astrocytes but not in cerebral astrocytes and in B50 and B104 neuroblastoma cells. The calcium ionophore 1 microM A23187, did not influence the expression of splice variants in either astrocytes or neuroblastoma cells. These findings suggest that spinal cord astrocytes may maintain a unique regulatory pathway that participates in the control of Na+ channel mRNA expression.
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Department of Medicine, University of Alabama at Birmingham 35294, USA.
Waxman
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D017398:Alternative Splicing; D000595:Amino Acid Sequence; D000818:Animals; D000831:Animals, Newborn; D001253:Astrocytes / Q000187:drug effects / Q000378:metabolism*; D001254:Astrocytoma / Q000378:metabolism*; D001921:Brain / Q000378:metabolism; D003994:Bucladesine / Q000494:pharmacology; D000001:Calcimycin / Q000494:pharmacology; D002478:Cells, Cultured; D014644:Genetic Variation; D046911:Macromolecular Substances; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D011487:Protein Conformation; D051381:Rats; D017207:Rats, Sprague-Dawley; D015222:Sodium Channels / Q000096:biosynthesis* / Q000737:chemistry / Q000502:physiology; D013116:Spinal Cord / Q000378:metabolism; D015854:Up-Regulation
D046911:Macromolecular Substances; D015222:Sodium Channels; D000001:Calcimycin; D003994:Bucladesine