Glucocorticoid-mediated regulation of utrophin levels in human muscle fibers.
Previous studies on transgenic mice indicate that upregulation of utrophin protein may offer a potential treatment strategy for Duchenne muscular dystrophy. We have analyzed the effect of the glucocorticoid 6alpha-methylprednisolone-21 sodium succinate on utrophin protein levels, using a cell-based assay with differentiated human myotubes, derived from biopsies of healthy individuals or Duchenne muscular dystrophy patients. We found that within 5-7 days 6alpha-methylprednisolone-21 sodium succinate increases utrophin protein up to approximately 40% in both normal and dystrophin-deficient myotubes compared to untreated control cultures. When analyzed in promoter-reporter assays 6alpha-methylprednisolone-21 sodium succinate activated a utrophin promoter A-fragment but did not activate a utrophin promoter B-fragment. Surprisingly, endogenous levels of utrophin mRNA in 6alpha-methylprednisolone-21 sodium succinate-treated muscle cells were unaltered indicating that the utrophin-inducing effect of glucocorticoids may be a result of post-transcriptional mechanisms. We have also analyzed 66 glucocorticoids for their effect on utrophin protein levels and found that glucocorticoids in general are able to induce utrophin protein in human myotubes.
MyoContract Pharmaceutical Research Ltd., Klingelbergstrasse 70, CH-4056 Basel, Switzerland.
Isabelle
I
Courdier-Fruh
Lee
L
Barman
Alexandre
A
Briguet
Thomas
T
Meier
D003598:Cytoskeletal Proteins / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D005938:Glucocorticoids / Q000037:antagonists & inhibitors / Q000378:metabolism* / Q000494:pharmacology*; D006727:Hormone Antagonists / Q000494:pharmacology; D006801:Humans; D008565:Membrane Proteins / Q000187:drug effects* / Q000235:genetics / Q000378:metabolism*; D008775:Methylprednisolone / Q000494:pharmacology*; D015735:Mifepristone / Q000494:pharmacology; D018485:Muscle Fibers, Skeletal / Q000378:metabolism*; D020388:Muscular Dystrophy, Duchenne / Q000188:drug therapy / Q000378:metabolism*; D016133:Polymerase Chain Reaction; D011401:Promoter Regions, Genetic; D012333:RNA, Messenger / Q000378:metabolism; D015854:Up-Regulation; D049411:Utrophin
D003598:Cytoskeletal Proteins; D005938:Glucocorticoids; D006727:Hormone Antagonists; D008565:Membrane Proteins; D012333:RNA, Messenger; D049411:Utrophin; D015735:Mifepristone; D008775:Methylprednisolone