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Mol. Cell. Biol., Apr 1996, 1649-1658, Vol 16, No. 4
DB Donoviel, MA Shield, JN Buskin, HS Haugen, CH Clegg and SD Hauschka
Regulatory regions of the mouse muscle creatine kinase (MCK) gene,
previously discovered by analysis in cultured muscle cells, were analyzed
in transgenic mice. The 206-bp MCK enhancer at nt-1256 was required for
high-level expression of MCK-chloramphenicol acetyltransferase fusion genes
in skeletal and cardiac muscle; however, unlike its behavior in cell
culture, inclusion of the 1-kb region of DNA between the enhancer and the
basal promoter produced a 100-fold increase in skeletal muscle activity.
Analysis of enhancer control elements also indicated major differences
between their properties in transgenic muscles and in cultured muscle
cells. Transgenes in which the enhancer right E box or CArG element were
mutated exhibited expression levels that were indistinguishable from the
wild-type transgene. Mutation of three conserved E boxes in the MCK
1,256-bp 5' region also had no effect on transgene expression in thigh
skeletal muscle expression. All these mutations significantly reduced
activity in cultured skeletal myocytes. However, the enhancer AT-rich
element at nt - 1195 was critical for expression in transgenic skeletal
muscle. Mutation of this site reduced skeletal muscle expression to the
same level as transgenes lacking the 206-bp enhancer, although mutation of
the AT-rich site did not affect cardiac muscle expression. These results
demonstrate clear differences between the activity of MCK regulatory
regions in cultured muscles cells and in whole adult transgenic muscle.
This suggests that there are alternative mechanism of regulating the MCK
gene in skeletal and cardiac muscle under different physiological states.
Copyright © 1996, American Society for Microbiology
Analysis of muscle creatine kinase gene regulatory elements in skeletal and cardiac muscles of transgenic mice
Department of Biochemistry, University of Washington, Seattle, 98195- 7350, USA.
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