Key Points
- Characterize the cis-regulatory elements and transcription factor binding sites that govern muscle-specific expression of the rat skeletal muscle type 1 sodium channel (SkM1) gene.
- Sequenced a 3.1-kilobase genomic fragment (-1062 to +311) containing the 5'-flanking region, first exon, and part of the first intron of rat SkM1.
- Identified transcription start sites and functionally analyzed the basal promoter, an upstream repressor, and downstream positive regulatory elements.
- The basal promoter (-65/+11) initiates transcription across multiple start sites (+1 to +30) without cell-type specificity, while an upstream repressor (-174/-65) restricts expression to skeletal muscle.
- Two distinct E-boxes direct opposing regulatory functions: an activating E-box at -31/-26 binds myogenic basic helix-loop-helix factors, whereas a repressive E-box at -90/-85 binds a separate protein complex.
Structured PICO
PPopulationRat skeletal muscle type 1 sodium channel (SkM1) gene model
IInterventionCharacterization of cis-regulatory elements (E boxes)
OOutcomeMuscle-specific gene expression regulationsurrogate
Two specific E-boxes are critical for the positive and negative regulation of muscle-specific expression of the rat skeletal muscle type 1 sodium channel gene.