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In vivo regulation of the beta-myosin heavy chain gene in soleus muscle of suspended and weight-bearing ratsIn the weight-bearing hindlimb soleus muscle of the rat, approximately 90% of muscle fibers express the beta-myosin heavy chain (beta-MHC) isoform protein. Hindlimb suspension (HS) causes the MHC isoform population to shift from beta toward the fast MHC isoforms. Our aim was to establish a model to test the hypothesis that this shift in expression is transcriptionally regulated through specific cis elements of the beta-MHC promoter. With the use of a direct gene transfer approach, we determined the activity of different length beta-MHC promoter fragments, linked to a firefly luciferase reporter gene, in soleus muscle of control and HS rats. In weight-bearing rats, the relative luciferase activity of the longest beta-promoter fragment (-3500 bp) was threefold higher than the shorter promoter constructs, which suggests that an enhancer sequence is present in the upstream promoter region. After 1 wk of HS, the reporter activities of the -3500-, -914-, and -408-bp promoter constructs were significantly reduced ( approximately 40%), compared with the control muscles. However, using the -215-bp construct, no differences in promoter activity were observed between HS and control muscles, which indicates that the response to HS in the rodent appears to be regulated within the -408 and -215 bp of the promoter.
Document ID
20040141544
Acquisition Source
Legacy CDMS
Document Type
Reprint (Version printed in journal)
Authors
Giger, J. M.
(University of California Irvine 92697, United States)
Haddad, F.
Qin, A. X.
Baldwin, K. M.
Date Acquired
August 22, 2013
Publication Date
June 1, 2000
Publication Information
Publication: American journal of physiology. Cell physiology
Volume: 278
Issue: 6
ISSN: 0363-6143
Subject Category
Aerospace Medicine
Funding Number(s)
CONTRACT_GRANT: HAR-30346
Distribution Limits
Public
Copyright
Other
Keywords
Non-NASA Center
NASA Program Biomedical Research and Countermeasures
NASA Discipline Musculoskeletal

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