Format

Send to

Choose Destination
Mol Cell Biol. 2014 Sep 15;34(18):3450-60. doi: 10.1128/MCB.00426-14. Epub 2014 Jul 7.

Insulin receptor substrates are essential for the bioenergetic and hypertrophic response of the heart to exercise training.

Author information

1
Fraternal Order of Eagles Diabetes Research Center and Division of Endocrinology and Metabolism, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA Division of Endocrinology, Metabolism and Diabetes and Program in Molecular Medicine, University of Utah School of Medicine, Salt Lake City, Utah, USA.
2
Division of Endocrinology, Metabolism and Diabetes and Program in Molecular Medicine, University of Utah School of Medicine, Salt Lake City, Utah, USA Division of Molecular and Cellular Pathology, Department of Pathology, University of Alabama at Birmingham, Birmingham, Alabama, USA.
3
Division of Endocrinology, Metabolism and Diabetes and Program in Molecular Medicine, University of Utah School of Medicine, Salt Lake City, Utah, USA.
4
Fraternal Order of Eagles Diabetes Research Center and Division of Endocrinology and Metabolism, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA.
5
Division of Endocrinology, Children's Hospital Boston, Harvard Medical School, Boston, Massachusetts, USA.
6
Fraternal Order of Eagles Diabetes Research Center and Division of Endocrinology and Metabolism, Roy J. and Lucille A. Carver College of Medicine, University of Iowa, Iowa City, Iowa, USA Division of Endocrinology, Metabolism and Diabetes and Program in Molecular Medicine, University of Utah School of Medicine, Salt Lake City, Utah, USA DRCadmin@uiowa.edu.

Abstract

Insulin and insulin-like growth factor 1 (IGF-1) receptor signaling pathways differentially modulate cardiac growth under resting conditions and following exercise training. These effects are mediated by insulin receptor substrate 1 (IRS1) and IRS2, which also differentially regulate resting cardiac mass. To determine the role of IRS isoforms in mediating the hypertrophic and metabolic adaptations of the heart to exercise training, we subjected mice with cardiomyocyte-specific deletion of either IRS1 (CIRS1 knockout [CIRS1KO] mice) or IRS2 (CIRS2KO mice) to swim training. CIRS1KO hearts were reduced in size under basal conditions, whereas CIRS2KO hearts exhibited hypertrophy. Following exercise swim training in CIRS1KO and CIRS2KO hearts, the hypertrophic response was equivalently attenuated, phosphoinositol 3-kinase (PI3K) activation was blunted, and prohypertrophic signaling intermediates, such as Akt and glycogen synthase kinase 3β (GSK3β), were dephosphorylated potentially on the basis of reduced Janus kinase-mediated inhibition of protein phosphatase 2a (PP2A). Exercise training increased peroxisome proliferator-activated receptor gamma coactivator 1-alpha (PGC-1α) protein content, mitochondrial capacity, fatty acid oxidation, and glycogen synthesis in wild-type (WT) controls but not in IRS1- and IRS2-deficient hearts. PGC-1α protein content remained unchanged in CIRS1KO but decreased in CIRS2KO hearts. These results indicate that although IRS isoforms play divergent roles in the developmental regulation of cardiac size, these isoforms exhibit nonredundant roles in mediating the hypertrophic and metabolic response of the heart to exercise.

PMID:
25002528
PMCID:
PMC4135616
DOI:
10.1128/MCB.00426-14
[Indexed for MEDLINE]
Free PMC Article

Supplemental Content

Full text links

Icon for HighWire Icon for PubMed Central
Loading ...
Support Center