title: Deficiency of cardiac Acyl-CoA synthetase-1 induces diastolic dysfunction, but pathologic hypertrophy is reversed by rapamycin.
abstract: In mice with temporally-induced cardiac-specific deficiency of acyl-CoA synthetase-1 (Acsl1(H-/-)), the heart is unable to oxidize long-chain fatty acids and relies primarily on glucose for energy. These metabolic changes result in the development of both a spontaneous cardiac hypertrophy and increased phosphorylated S6 kinase (S6K), a substrate of the mechanistic target of rapamycin, mTOR. Doppler echocardiography revealed evidence of significant diastolic dysfunction, indicated by a reduced E/A ratio and increased mean performance index, although the deceleration time and the expression of sarco/endoplasmic reticulum calcium ATPase and phospholamban showed no difference between genotypes. To determine the role of mTOR in the development of cardiac hypertrophy, we treated Acsl1(H-/-) mice with rapamycin. Six to eight week old Acsl1(H-/-) mice and their littermate controls were given i.p. tamoxifen to eliminate cardiac Acsl1, then concomitantly treated for 10weeks with i.p. rapamycin or vehicle alone. Rapamycin completely blocked the enhanced ventricular S6K phosphorylation and cardiac hypertrophy and attenuated the expression of hypertrophy-associated fetal genes, including α-skeletal actin and B-type natriuretic peptide. mTOR activation of the related Acsl3 gene, usually associated with pathologic hypertrophy, was also attenuated in the Acsl1(H-/-) hearts, indicating that alternative pathways of fatty acid activation did not compensate for the loss of Acsl1. Compared to controls, Acsl1(H-/-) hearts exhibited an 8-fold higher uptake of 2-deoxy[1-(14)C]glucose and a 35% lower uptake of the fatty acid analog 2-bromo[1-(14)C]palmitate. These data indicate that Acsl1-deficiency causes diastolic dysfunction and that mTOR activation is linked to the development of cardiac hypertrophy in Acsl1(H-/-) mice.
authors.affiliation: McAllister Heart Institute, University of NC at Chapel Hill, 27599, USA. Electronic address: david_paul@med.unc.edu.
authors.forename: David S
authors.initials: DS
authors.lastname: Paul
authors.affiliation: Department of Nutrition, University of NC at Chapel Hill, 27599, USA. Electronic address: tgrevengoed@gmail.com.
authors.forename: Trisha J
authors.initials: TJ
authors.lastname: Grevengoed
authors.affiliation: Department of Nutrition, University of NC at Chapel Hill, 27599, USA. Electronic address: fpascual@live.unc.edu.
authors.forename: Florencia
authors.initials: F
authors.lastname: Pascual
authors.affiliation: Department of Nutrition, University of NC at Chapel Hill, 27599, USA. Electronic address: jessie.ellis@gmail.com.
authors.forename: Jessica M
authors.initials: JM
authors.lastname: Ellis
authors.affiliation: McAllister Heart Institute, University of NC at Chapel Hill, 27599, USA; Department of Pathology and Laboratory Medicine, University of NC at Chapel Hill, 27599, USA. Electronic address: monte_willis@med.unc.edu.
authors.forename: Monte S
authors.initials: MS
authors.lastname: Willis
authors.affiliation: Department of Nutrition, University of NC at Chapel Hill, 27599, USA; McAllister Heart Institute, University of NC at Chapel Hill, 27599, USA. Electronic address: rcoleman@unc.edu.
authors.forename: Rosalind A
authors.initials: RA
authors.lastname: Coleman
mesh_terms: D000818:Animals; D006332:Cardiomegaly / Q000188:drug therapy / Q000201:enzymology* / Q000473:pathology; D003066:Coenzyme A Ligases / Q000172:deficiency / Q000235:genetics* / Q000378:metabolism; D004721:Endoplasmic Reticulum / Q000378:metabolism; D054144:Heart Failure, Diastolic / Q000201:enzymology* / Q000235:genetics / Q000473:pathology; D006801:Humans; D050356:Lipid Metabolism / Q000235:genetics; D051379:Mice; D010084:Oxidation-Reduction; D020123:Sirolimus / Q000008:administration & dosage*; D058570:TOR Serine-Threonine Kinases / Q000235:genetics*; D013629:Tamoxifen / Q000494:pharmacology
chemical_list: D013629:Tamoxifen; C546842:MTOR protein, human; D058570:TOR Serine-Threonine Kinases; D003066:Coenzyme A Ligases; D020123:Sirolimus
keywords: Fatty acid oxidation; Gene expression; Insulin resistance; Substrate switching; Ventricular function; mTOR