Tandem redundant promoter elements drive rSkM2 voltage-sensitive Na+ channel expression

rSk.M2 gene cis-elements were localized by deletion, scanning, and point nmtalion analysis of the -129/+1 promoter segment. Transient transfection analysis of these mutations reveals the presence of a distal promoter (-129/-50) and a proximal promoter (-5T/ -f-1 ). each of which can drive C'AT expression in muscle c.-lls (c.f.. 3T:t fibroblasts). They contain Spl sites, a C-rich {CCAC-box-like} motif, but no E-boxes [DNA & Cell Biology. 1J. 9 23. 1994]. Scanning the ~'7/-i-l segment 10 bp at a time with block mutations showed that all regions (except -29 to -20) are essential fur expression but especially -57 to -.r>0. 'Hie -129/-58 segment is similar to the -57/-+-I region in sequence and in the i omplrxf.'s formed in FMSA. We conclude that the 129/-M segment contain landein promoters to protect from inadvertant silencing of this gene. Super shifts with aiitibodios tn Myo-I). Spl. and myofvte nuclear factor in KMSAs implicalte Spl and novel transcription factor.