Lm. Angus et al., Role of intronic E- and N-box motifs in the transcriptional induction of the acetylcholinesterase gene during myogenic differentiation, J BIOL CHEM, 276(20), 2001, pp. 17603-17609
In this study, we examined whether an intronic N-box motif is involved in t
he expression of acetylchollinesterase (AChE) during myogenesis, We determi
ned that AChE transcripts are barely detectable in cultured myoblasts and t
hat their levels increase dramatically in myotubes, Nuclear run-on assays r
evealed that this increase was accompanied by a parallel induction in the t
ranscriptional activity of the AChE gene, These changes in transcription we
re also observed in transfection experiments using AChE promoter-reporter g
ene constructs. Mutation of the intronic N-box at position +755 base pairs
(bp) reduced by more than 70% expression of the reporter gene in myotubes,
Disruption of an adjacent E-box, at position +767 bp, also reduced expressi
on of the reporter gene following myogenic differentiation. Co-transfection
experiments using AChE promoter-reporter gene constructs and a myogenin ex
pression vector showed that expression of this regulatory factor increased
expression of the reporter gene in myotubes. Although the AChE promoter con
tains multiple E-boxes, mutation of this intronic one was sufficient to pre
vent the myogenin-induced increase in reporter gene expression. Together, t
hese results indicate that changes in AChE gene transcription occur during
myogenesis and highlight the contribution of the intronic Nand E-box motifs
in the developmental regulation of the AChE gene in skeletal muscle.