TY - JOUR
T1 - Translational activation of 5′-TOP mRNA in pressure overload myocardium
AU - Tuxworth, William J.
AU - Shiraishi, Hirokazu
AU - Moschella, Phillip C.
AU - Yamane, Kentaro
AU - McDermott, Paul J.
AU - Kuppuswamy, Dhandapani
N1 - Funding Information:
We thank Charlene Kerr for her excellent technical assistance. This study was supported by Program Project Grant HL-48788 and by Merit and REAP awards from the Research Service of Veterans Affairs, and Institutional Postdoctoral Training Grant HL-07260 from the NIH (to W.J.T).
PY - 2008/1
Y1 - 2008/1
N2 - The present study was conducted to determine the magnitude and duration of ribosomal protein translation in response to pressure overload and determine if additional, paracrine events associated with mechanical transduction, such as integrin activation using a bioactive peptide ligand, RGD or endothelin stimulation lead to ribosomal protein translation. Polysome analysis of ventricular tissue samples obtained from an in vivo model of right-ventricular pressure overload (RVPO) showed a significant shift in the proportion of a 5′-terminal oligopyrimidine (5′-TOP) mRNA, rpL32, associated with the polysomal fraction when compared with non-5′-TOP mRNAs, β-actin and β-myosin heavy chain (β-MHC), in the early stages of the hypertrophic response (24-48 h). Furthermore, this increase in polysome-bound rpL32 mRNA was accompanied by the phosphorylation of mammalian target of rapamycin (mTOR), p70 S6 kinase (S6K1), and S6 ribosomal protein. In our in vitro studies, treatment of primary cultures of adult feline cardiomyocytes (cardiocytes) with 100 nM endothelin, 9 mM RGD, 100 nM insulin, or 100 nM TPA activated mTOR via distinct signaling pathways and resulted in an increased proportion of polysome-bound rpL32 mRNA. Pre-treatment of cardiocytes with the mTOR inhibitor rapamycin blocked the agonist-induced rpL32 mRNA mobilization to polysomes. These results show that mechanisms that regulate ribosomal biogenesis in the myocardium are dynamically sensitive to pressure overload. Furthermore, our in vitro studies indicate that distinct pathways are operational during the early course of hypertrophic growth and converge to activate mTOR resulting in the translational activation of 5′-TOP mRNA.
AB - The present study was conducted to determine the magnitude and duration of ribosomal protein translation in response to pressure overload and determine if additional, paracrine events associated with mechanical transduction, such as integrin activation using a bioactive peptide ligand, RGD or endothelin stimulation lead to ribosomal protein translation. Polysome analysis of ventricular tissue samples obtained from an in vivo model of right-ventricular pressure overload (RVPO) showed a significant shift in the proportion of a 5′-terminal oligopyrimidine (5′-TOP) mRNA, rpL32, associated with the polysomal fraction when compared with non-5′-TOP mRNAs, β-actin and β-myosin heavy chain (β-MHC), in the early stages of the hypertrophic response (24-48 h). Furthermore, this increase in polysome-bound rpL32 mRNA was accompanied by the phosphorylation of mammalian target of rapamycin (mTOR), p70 S6 kinase (S6K1), and S6 ribosomal protein. In our in vitro studies, treatment of primary cultures of adult feline cardiomyocytes (cardiocytes) with 100 nM endothelin, 9 mM RGD, 100 nM insulin, or 100 nM TPA activated mTOR via distinct signaling pathways and resulted in an increased proportion of polysome-bound rpL32 mRNA. Pre-treatment of cardiocytes with the mTOR inhibitor rapamycin blocked the agonist-induced rpL32 mRNA mobilization to polysomes. These results show that mechanisms that regulate ribosomal biogenesis in the myocardium are dynamically sensitive to pressure overload. Furthermore, our in vitro studies indicate that distinct pathways are operational during the early course of hypertrophic growth and converge to activate mTOR resulting in the translational activation of 5′-TOP mRNA.
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U2 - 10.1007/s00395-007-0682-z
DO - 10.1007/s00395-007-0682-z
M3 - Article
C2 - 17955327
AN - SCOPUS:37349099513
SN - 0300-8428
VL - 103
SP - 41
EP - 53
JO - Basic Research in Cardiology
JF - Basic Research in Cardiology
IS - 1
ER -