Euglycemic hyperinsulinemia hyperaminoacidemia specifically
decreases skeletal muscle ubiquitin mrna in goats.
Larbaud, Daniel, Elisabeth Debras, Daniel Taillandier, Susan E.
Samuels, Sandrine Temparis, Claude Champredon, Jean Grizard, and
Didier Attaix.
Centre de Recherche en Nutrition Humaine et Institut National de la
Recherche Agronomique, Unit[acute]e d'Etude du M[acute]etabolisme
Azot[acute]e, 63122 Ceyrat, France
APStracts 3:0113E, 1996.
Insulin inhibits protein breakdown at the whole body level, but
neither the tissues nor the proteolytic pathways on which insulin
exerts its antiproteolytic effect are well characterized. We measured
the effects of insulin on mRNA levels for cathepsin D and m-calpain
(a lysosomal and Ca2+-dependent proteinase, respectively) and
ubiquitin (a component of ubiquitin-dependent proteolysis) in
skeletal muscle, skin, liver and intestine. We used a 6 h
hyperinsulinemic, euglycemic, and hyperaminoacidemic clamp in goats,
a species in which insulin markedly inhibited whole body protein
breakdown under similar conditions (Tesseraud et al., Am. J. Physiol.
265 (Endocrinol. Metab. 28): E402-E413, 1993). Hyperinsulinemia
hyperaminoacidemia had no effect on cathepsin D m-calpain, and
ubiquitin mRNA levels in liver, skin, and jejunum. In contrast,
depressed ubiquitin mRNA levels were seen in skeletal muscle without
any concomitant reduction in mRNA levels for cathepsin D, m-calpain,
and other components of the ubiquitin-dependent proteolytic pathway.
The reduced ubiquitin mRNA levels in skeletal muscle may represent a
possible mechanism explaining the antiproteolytic effect of insulin
in vivo.
Received 2 January 1996; accepted in final form 8 May 1996.
APS Manuscript Number E1-6.
Article publication pending Am. J. Physiol. (Endocrinol. Metab.).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 17 June 96