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Appears in Collections:Faculty of Health Sciences and Sport Journal Articles
Peer Review Status: Refereed
Title: A Limited Role for PI(3,4,5)P-3 Regulation in Controlling Skeletal Muscle Mass in Response to Resistance Exercise
Author(s): Hamilton, David Lee
Philp, Andrew
MacKenzie, Matthew G
Baar, Keith
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Keywords: Muscle strength
Exercise Physiological aspects
Physical education and training
Issue Date: 16-Jul-2010
Date Deposited: 29-Apr-2013
Citation: Hamilton DL, Philp A, MacKenzie MG & Baar K (2010) A Limited Role for PI(3,4,5)P-3 Regulation in Controlling Skeletal Muscle Mass in Response to Resistance Exercise. PLoS ONE, 5 (7), Article e11624.
Abstract: Background: Since activation of the PI3K/(protein kinase B; PKB/akt) pathway has been shown to alter muscle mass and growth, the aim of this study was to determine whether resistance exercise increased insulin like growth factor (IGF) I/ phosphoinositide 3-kinase (PI3K) signalling and whether altering PI(3,4,5)P3 metabolism genetically would increase load induced muscle growth. Methodology/Principal Findings: Acute and chronic resistance exercise in wild type and muscle specific PTEN knockout mice were used to address the role of PI(3,4,5)P3 regulation in the development of skeletal muscle hypertrophy. Acute resistance exercise did not increase either IGF-1 receptor phosphorylation or IRS1/2 associated p85. Since insulin/IGF signalling to PI3K was unchanged, we next sought to determine whether inactivation of PTEN played a role in load-induced muscle growth. Muscle specific knockout of PTEN resulted in small but significant increases in heart (PTEN+/+ = 5.00±0.02 mg/g, PTEN-/- = 5.50±0.09 mg/g), and TA (PTEN+/+ = 1.74±0.04 mg/g, PTEN-/- = 1.89 ±0.03) muscle mass, while the GTN, SOL, EDL and PLN remain unchanged. Following ablation, hypertrophy of the PLN, SOL or EDL muscles was similar between PTEN-/- and PTEN+/+ animals. Even though there were some changes in overload-induced PKB and S6K1 phosphorylation, 1 hr following acute resistance exercise there was no difference in the phosphorylation state of S6K1 Thr389 between genotypes. Conclusions/Significance: These data suggest that physiological loading does not lead to the enhanced activation of the PI3K/PKB/mTORC1 axis and that neither PI3K activation nor PTEN, and by extension PI(3,4,5)P3 levels, play a significant role in adult skeletal muscle growth.
DOI Link: 10.1371/journal.pone.0011624
Rights: © 2010 Hamilton et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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