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Titolo:
Effects of different activity and inactivity paradigms on myosin heavy chain gene expression in striated muscle
Autore:
Baldwin, KM; Haddad, F;
Indirizzi:
Univ Calif Irvine, Dept Physiol & Biophys, Irvine, CA 92697 USA Univ CalifIrvine Irvine CA USA 92697 iol & Biophys, Irvine, CA 92697 USA
Titolo Testata:
JOURNAL OF APPLIED PHYSIOLOGY
fascicolo: 1, volume: 90, anno: 2001,
pagine: 345 - 357
SICI:
8750-7587(200101)90:1<345:EODAAI>2.0.ZU;2-L
Fonte:
ISI
Lingua:
ENG
Soggetto:
THYROID-HORMONE RECEPTOR; RAT SKELETAL-MUSCLE; MYOFIBRILLAR ATPASE ACTIVITY; SPINAL-CORD INJURY; M-VASTUS-LATERALIS; IN-VIVO REGULATION; ISOFORM EXPRESSION; SINGLE FIBERS; SOLEUS MUSCLE; POSTNATAL-DEVELOPMENT;
Keywords:
muscle plasticity; neonatal development; functional overload; spaceflight; spinal injury; endurance exercise; thyroid state; gene transcription;
Tipo documento:
Review
Natura:
Periodico
Settore Disciplinare:
Life Sciences
Citazioni:
122
Recensione:
Indirizzi per estratti:
Indirizzo: Baldwin, KM Univ Calif Irvine, Dept Physiol & Biophys, Irvine, CA 92697 USA Univ Calif Irvine Irvine CA USA 92697 s, Irvine, CA 92697 USA
Citazione:
K.M. Baldwin e F. Haddad, "Effects of different activity and inactivity paradigms on myosin heavy chain gene expression in striated muscle", J APP PHYSL, 90(1), 2001, pp. 345-357

Abstract

The goal of this mini-review is to summarize findings concerning the role that different models of muscular activity and inactivity play in altering gene expression of the myosin heavy chain (MHC) family of motor proteins inmammalian cardiac and skeletal muscle. This was done in the context of examining parallel findings concerning the role that thyroid hormone (T-3, 3,5,3'-triiodothyronine) plays in MHC expression. Findings show that both cardiac and skeletal muscles of experimental animals are initially undifferentiated at birth and then undergo a marked level of growth and differentiationin attaining the adult MHC phenotype in a T-3/activity level-dependent fashion. Cardiac MHC expression in small mammals is highly sensitive to thyroid deficiency, diabetes, energy deprivation, and hypertension; each of theseinterventions induces upregulation of the beta -MHC isoform, which functions to economize circulatory function in the face of altered energy demand. In skeletal muscle, hyperthyroidism, as well as interventions that unload or reduce the weight-bearing activity of the muscle, causes slow to fast MHCconversions. Fast to slow conversions, however, are seen under hypothyroidism or when the muscles either become chronically overloaded or subjected to intermittent loading as occurs during resistance training and endurance exercise. The regulation of MHC gene expression by T-3 or mechanical stimuliappears to be strongly regulated by transcriptional events, based on recent findings on transgenic models and animals transfected with promoter-reporter constructs. However, the mechanisms by which T-3 and mechanical stimuliexert their control on transcriptional processes appear to be different. Additional findings show that individual skeletal muscle fibers have the genetic machinery to express simultaneously all of the adult MHCs, e.g., slow type I and fast IIa, IIx, and IIb, in unique combinations under certain experimental conditions. This degree of heterogeneity among the individual fibers would ensure a large functional diversity in performing complex movement patterns. Future studies must now focus on 1) the signaling pathways and the underlying mechanisms governing the transcriptional/translational machinery that control this marked degree of plasticity and 2) the morphologicalorganization and functional implications of the muscle fiber's capacity toexpress such a diversity of motor proteins.

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Documento generato il 05/12/20 alle ore 01:23:27