Rheb activates protein synthesis and growth in adult rat ventricular cardiomyocytes

Yanni Wang, Brandon P H Huang, Dan S. Luciani, Xuemin Wang, James D. Johnson, Christopher G. Proud

Research output: Contribution to journalArticlepeer-review

20 Citations (Scopus)

Abstract

The mammalian target of rapamycin complex 1 (mTORC1), a key regulator of protein synthesis, growth and proliferation in mammalian cells, is implicated in the development of cardiac hypertrophy. Ras homolog enriched in brain (Rheb) positively regulates mTORC1. We have studied whether Rheb is sufficient to activate mTOR signaling and promote protein synthesis and cardiac hypertrophy in adult rat ventricular cardiomyocytes (ARVC). Rheb was overexpressed via an adenoviral vector in isolated ARVC. Overexpression of Rheb in ARVC activated mTORC1 signaling, several components of the translational machinery and stimulated protein synthesis. Our direct visualization approach to determine ARVC size revealed that overexpression of Rheb also induced cell growth and indeed did so to similar extent to the hypertrophic agent, phenylephrine (PE). Despite potent activation of mTORC1 signaling, overexpression of Rheb did not induce expression of the cardiac hypertrophic marker mRNAs for brain natriuretic peptide and atrial natriuretic factor, while PE treatment did markedly increase their expression. All the effects of Rheb were blocked by rapamycin, confirming their dependence on mTORC1 signaling. Our findings reveal that Rheb itself can activate both protein synthesis and cell growth in ARVC and demonstrate the key role played by mTORC1 in the growth of cardiomyocytes.

Original languageEnglish
Pages (from-to)812-820
Number of pages9
JournalJournal of Molecular and Cellular Cardiology
Volume45
Issue number6
DOIs
Publication statusPublished or Issued - Dec 2008

Keywords

  • Cardiac hypertrophy
  • Growth
  • Protein synthesis
  • Rheb
  • mTOR

ASJC Scopus subject areas

  • Molecular Biology
  • Cardiology and Cardiovascular Medicine

Cite this