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Record 84 of 258
Nerve-responsive troponin I slow promoter does not respond to unloading
Author and Affiliation:
Criswell, D. S.(University of Texas Medical School, Department of Integrative Biology, Pharmacology, and Physiology, Houston, Texas 77030, United States)
Hodgson, V. R.
Hardeman, E. C.
Booth, F. W.
Abstract: We examined the regulation of the troponin I slow (TnIs) promoter during skeletal muscle unloading-induced protein isoform transition, by using a transgenic mouse line harboring the -4,200 to +12 base pairs region of the human TnIs promoter. Eighteen female transgenic mice ( approximately 30 g body mass) were randomly divided into two groups: weight-bearing (WB) controls (n = 9) and hindlimb unloaded (HU; n = 9). The HU mice were tail suspended for 7 days. Body mass was unchanged in the WB group but was reduced (-6%; P < 0.05) after the HU treatment. Absolute soleus muscle mass (-25%) and soleus mass relative to body mass (-16%) were both lower (P < 0.05) in the HU group compared with the WB mice. Northern blot analyses indicate that 7 days of HU result in a 64% decrease (P < 0.05) in the abundance of endogenous TnIs mRNA (microg/mg muscle) in the mouse soleus. Furthermore, there is a trend for the abundance of the fast troponin I mRNA to be increased (+34%). Analysis of transgenic chloramphenicol acetyltransferase activity in the soleus muscle revealed no difference (P > 0.05) between WB and HU groups. We conclude that additional elements are necessary for the TnIs gene to respond to an unloading-induced, slow-to-fast isoform transition stimulus.
Publication Date: Mar 01, 1998
Document ID:
20040172734
(Acquired Dec 09, 2004)
Subject Category: AEROSPACE MEDICINE
Document Type: Journal Article
Publication Information: Journal of applied physiology (Bethesda, Md. : 1985); p. 1083-7; (ISSN 8750-7587); Volume 84; 3
Publisher Information: United States
Description: In English
Distribution Limits: Unclassified; Publicly available; Unlimited
Rights: Copyright
NASA Terms: HINDLIMB SUSPENSION; NERVES; SKELETAL MUSCLE; UNLOADING; BIOSYNTHESIS; BODY WEIGHT; DEOXYRIBONUCLEIC ACID; ENZYMOLOGY; FEMALES; GENETICS; MICE; ORGAN WEIGHT; RIBONUCLEIC ACIDS; TRANSCRIPTION (GENETICS)
Other Descriptors: HINDLIMB SUSPENSION/PHYSIOLOGY; MUSCLE, SKELETAL/ENZYMOLOGY/PHYSIOLOGY; TROPONIN I/GENETICS/PHYSIOLOGY; ANIMALS; BLOTTING, NORTHERN; BODY WEIGHT/PHYSIOLOGY; CHLORAMPHENICOL O-ACETYLTRANSFERASE/BIOSYNTHESIS/GENETICS/METABOLISM; DNA PROBES; FEMALE; HUMAN; MICE; MICE, TRANSGENIC; ORGAN WEIGHT/PHYSIOLOGY; RNA/BIOSYNTHESIS; SUPPORT, NON-U.S. GOV'T; SUPPORT, U.S. GOV'T, NON-P.H.S; TRANSCRIPTION, GENETIC; NASA DISCIPLINE MUSCULOSKELETAL; NON-NASA CENTER
Availability Source: Other Sources
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