首页 | 本学科首页   官方微博 | 高级检索  
   检索      


Activation or inactivation of cardiac Akt/mTOR signaling diverges physiological from pathological hypertrophy
Authors:Kemi Ole Johan  Ceci Marcello  Wisloff Ulrik  Grimaldi Serena  Gallo Paolo  Smith Godfrey L  Condorelli Gianluigi  Ellingsen Oyvind
Institution:Institute of Biomedical and Life Sciences, University of Glasgow, UK. o.kemi@bio.gla.ac.uk
Abstract:Cardiomyocyte hypertrophy differs according to the stress exerted on the myocardium. While pressure overload-induced cardiomyocyte hypertrophy is associated with depressed contractile function, physiological hypertrophy after exercise training associates with preserved or increased inotropy. We determined the activation state of myocardial Akt signaling with downstream substrates and fetal gene reactivation in exercise-induced physiological and pressure overload-induced pathological hypertrophies. C57BL/6J mice were either treadmill trained for 6 weeks, 5 days/week, at 85-90% of maximal oxygen uptake (VO(2max)), or underwent transverse aortic constriction (TAC) for 1 or 8 weeks. Total and phosphorylated protein levels were determined with SDS-PAGE, and fetal genes by real-time RT-PCR. In the physiologically hypertrophied heart after exercise training, total Akt protein level was unchanged, but Akt was chronically hyperphosphorylated at serine 473. This was accompanied by activation of the mammalian target of rapamycin (mTOR), measured as phosphorylation of its two substrates: the ribosomal protein S6 kinase-1 (S6K1) and the eukaryotic translation initiation factor-4E binding protein-1 (4E-BP1). Exercise training did not reactivate the fetal gene program (beta-myosin heavy chain, atrial natriuretic factor, skeletal muscle actin). In contrast, pressure overload after TAC reactivated fetal genes already after 1 week, and partially inactivated the Akt/mTOR pathway and downstream substrates after 8 weeks. In conclusion, changes in opposite directions of the myocardial Akt/mTOR signal pathway appears to distinguish between physiological and pathological hypertrophies; exercise training associating with activation and pressure overload associating with inactivation of the Akt/mTOR pathway.
Keywords:
本文献已被 PubMed 等数据库收录!
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号