Characterization of 5'-regulatory region of human myostatin gene: regulation by dexamethasone in vitro.
We cloned and characterized a 3.3-kb fragment containing the 5'-regulatory region of the human myostatin gene. The promoter sequence contains putative muscle growth response elements for glucocorticoid, androgen, thyroid hormone, myogenic differentiation factor 1, myocyte enhancer factor 2, peroxisome proliferator-activated receptor, and nuclear factor-kappaB. To identify sites important for myostatin's gene transcription and regulation, eight deletion constructs were placed in C(2)C(12) and L6 skeletal muscle cells. Transcriptional activity of the constructs was found to be significantly higher in myotubes compared with that of myoblasts. To investigate whether glucocorticoids regulate myostatin gene expression, we incubated both cell lines with dexamethasone. On both occasions, dexamethasone dose dependently increased both the promoter's transcriptional activity and the endogenous myostatin expression. The effects of dexamethasone were blocked when the cells were coincubated with the glucocorticoid receptor antagonist RU-486. These findings suggest that glucocorticoids upregulate myostatin expression by inducing gene transcription, possibly through a glucocorticoid receptor-mediated pathway. We speculate that glucocorticoid-associated muscle atrophy might be due in part to the upregulation of myostatin expression.
Ma
K
K
Division of Endocrinology, Metabolism, and Molecular Medicine, Charles R. Drew University of Medicine and Science, Los Angeles, California 90509, USA. kuma@cdrewu.edu
Mallidis
C
C
Artaza
J
J
Taylor
W
W
Gonzalez-Cadavid
N
N
Bhasin
S
S
D001483:Base Sequence; D015153:Blotting, Western; D002478:Cells, Cultured; D003001:Cloning, Molecular; D015342:DNA Probes; D003907:Dexamethasone / Q000494:pharmacology*; D004742:Enhancer Elements, Genetic / Q000235:genetics; D005786:Gene Expression Regulation / Q000187:drug effects*; D005938:Glucocorticoids / Q000494:pharmacology*; D006801:Humans; D008969:Molecular Sequence Data; D018482:Muscle, Skeletal / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D055435:Myostatin; D009687:Nuclear Proteins / Q000378:metabolism; D012333:RNA, Messenger / Q000096:biosynthesis; D012045:Regulatory Sequences, Nucleic Acid / Q000235:genetics*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D013268:Stimulation, Chemical; D014158:Transcription, Genetic / Q000235:genetics; D014162:Transfection; D016212:Transforming Growth Factor beta / Q000096:biosynthesis / Q000235:genetics*
D015342:DNA Probes; D005938:Glucocorticoids; C525911:MSTN protein, human; D055435:Myostatin; D009687:Nuclear Proteins; D012333:RNA, Messenger; D016212:Transforming Growth Factor beta; D003907:Dexamethasone