Effects of exercise and insulin on mitogen-activated protein kinase
signaling pathways in rat skeletal muscle.
Goodyear, Laurie J., Pi-Yun Chang, Daniel J. Sherwood, Scott D.
Dufresne, and David E. Moller.
Research Division, Joslin Diabetes Center, Department of Medicine,
Brigham and Women's Hospital, and Harvard Medical School, the
Department of Medicine, Beth Israel Hospital, Boston, MA 02215, and
the Department of Molecular Endocrinology, Merck Research
Laboratories, Rahway, NJ 07065
APStracts 3:0099E, 1996.
Studies in mammalian cells have established the existence of at least
3 distinct mitogen-activated protein kinase (MAP kinase) signaling
pathways that are activated by a variety growth factors and/or
environmental stressors. We determined if physical exercise, a
physiological stressor, and insulin, a metabolic stimulator and
growth factor, activate the c-jun NH2 terminus kinase (JNK), p38
kinase, and/or the extracellular regulatory kinases (p42MAPK,
p44MAPK, or ERKs) signaling pathways in rat skeletal muscle. Animals
were studied immediately after running on a motorized treadmill for
10 to 60 min (20 m/min, 10% grade), or 5 to 30 min following an
intraperitoneal injection of insulin (20 U/rat). Exercise increased
skeletal muscle JNK activity by 2- to 3-fold throughout the time
course studied, whereas insulin did not significantly increase JNK
activity. p38 activity was slightly stimulated by exercise and not by
insulin. The ERK kinase pathway, as assessed by RSK2 activity assays
and phospho-specific ERK1/ERK2 immunoblotting, was stimulated by both
exercise and insulin. These data are the first demonstration of
exercise stimulating multiple intracellular signaling pathways in
skeletal muscle. Activation of these MAP kinase signaling pathways
may mediate changes in skeletal muscle growth and metabolism that
occur in response to exercise.
Received 28 March 1996; accepted in final form 3 May 1996.
APS Manuscript Number E156-6.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 28 May 96