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Focal adhesion proteins FAK and paxillin increase in hypertrophied skeletal muscle
Ist Teil von
American Journal of Physiology: Cell Physiology, 1999-07, Vol.277 (1), p.C152-C162
Ort / Verlag
United States
Erscheinungsjahr
1999
Quelle
Free E-Journal (出版社公開部分のみ)
Beschreibungen/Notizen
1 Department of Integrative
Biology, Pharmacology, and Physiology, University of Texas Medical
School, Houston 77030;
2 Department of Cell Biology,
Baylor College of Medicine, Houston, Texas 77030; and
3 Department of Clinical Research,
University of Bern, 3004 Bern, Switzerland
Components of signaling pathways for mechanotransduction during
load-induced enlargement of skeletal muscle have not been completely
defined. We hypothesized that loading of skeletal muscle would result
in an adaptive increase in the expression of two focal adhesion complex
(FAC)-related proteins, focal adhesion kinase (FAK) and paxillin, as
well as increased FAK activity. FAK protein was immunolocalized to the
sarcolemmal region of rooster anterior latissimus dorsi (ALD) myofibers
in the middle of the ALD muscle. FAK (77 and 81%) and paxillin (206 and 202%) protein concentrations per unit of total protein in Western
blots increased significantly after 1.5 and 7 days, but not after 13 days, of stretch-induced hypertrophy-hyperplasia of the ALD muscle. FAK autokinase activity in immunoprecipitates was increased after 1.5, 7, and 13 days in stretched ALD muscles. To determine whether increased
FAK and paxillin protein concentrations are associated with hypertrophy
and/or new fiber formation, two additional experiments were performed.
First, during formation of primary chicken myotubes (a model of new
fiber formation), FAK protein concentration (63%), FAK activity
(157%), and paxillin protein concentration (97%) increased compared
with myoblasts. Second, FAK (112% and 611%) and paxillin (87% and
431%) protein concentrations per unit of total protein in the soleus
muscle increased at 1 and 8 days after surgical ablation of the
synergistic gastrocnemius muscle (a model of hypertrophy without
hyperplasia). Thus increases in components of the FAC occur in
hypertrophying muscle of animals and in newly formed muscle fibers in
culture. Furthermore, increased FAK activity suggests a possible
convergence of signaling at the FAC in load-induced growth of skeletal muscle.
hypertrophy; mechanotransduction; focal adhesion complex