SRF protein is upregulated during stretch-induced hypertrophy of rooster ALD muscle.
Serum response element 1 has previously been reported to be necessary and sufficient for activation of the skeletal alpha-actin promoter during hypertrophy of the anterior latissimus dorsi (ALD) muscle of roosters [J. A. Carson, R. J. Schwartz, and F. W. Booth. Am. J. Physiol. 270 (Cell Physiol. 39): C1624-C1633, 1996]. Serum response factor (SRF) protein is the transcription factor that binds as a homodimer to serum response element 1 and activates the skeletal alpha-actin promoter. An increased expression of exogenous SRF protein in replicating C2C12 myoblasts induced a three- to fourfold activation of the skeletal alpha-actin promoter (L. Wei, W. Zhou, J. D. Croissant, F.-E. Johansen, R. Prywes, A. Balasubramamyan, and R. J. Schwartz. J. Biol. Chem. 273: 30287-30294, 1998). Thus we hypothesized that SRF protein concentration would be increased during hypertrophy of skeletal muscle. In the present study, 10% of the rooster's body weight was attached to the left wing to induce enlargement of the ALD muscle compared with the contralateral muscle. With Western analysis, a significant increase in SRF protein per gram of wet weight of the ALD muscle was noted at 7 and 13 days of hypertrophy. Furthermore, the increase in SRF protein occurred in both crude nuclear protein and cytoplasmic fractions in 7-day stretched ALD muscles. This is the first report showing increased protein concentration for a transcription factor whose regulatory element in the skeletal alpha-actin promoter has previously been shown to be required for the transduction of a hypertrophy signal in overloaded skeletal muscle of an animal.
Flück
M
M
Department of Integrative Biology, Physiology, and Pharmacology, University of Texas Medical School, Houston, Texas 77030, USA.
Carson
J A
JA
Schwartz
R J
RJ
Booth
F W
FW
D000818:Animals; D015153:Blotting, Western; D002467:Cell Nucleus / Q000378:metabolism; D002478:Cells, Cultured; D002642:Chick Embryo; D002645:Chickens / Q000378:metabolism*; D004268:DNA-Binding Proteins / Q000096:biosynthesis*; D004591:Electrophoresis, Polyacrylamide Gel; D004926:Escherichia coli / Q000378:metabolism; D007120:Immunochemistry; D008297:Male; D024510:Muscle Development; D009124:Muscle Proteins / Q000096:biosynthesis; D018482:Muscle, Skeletal / Q000166:cytology / Q000254:growth & development / Q000502:physiology*; D009687:Nuclear Proteins / Q000096:biosynthesis*; D009929:Organ Size; D010812:Physical Stimulation; D012333:RNA, Messenger / Q000096:biosynthesis; D011994:Recombinant Proteins / Q000378:metabolism; D026362:Serum Response Factor; D015854:Up-Regulation / Q000502:physiology*
D004268:DNA-Binding Proteins; D009124:Muscle Proteins; D009687:Nuclear Proteins; D012333:RNA, Messenger; D011994:Recombinant Proteins; D026362:Serum Response Factor