title: Mammalian target of rapamycin (mTOR) inhibition with rapamycin improves cardiac function in type 2 diabetic mice: potential role of attenuated oxidative stress and altered contractile protein expression.
abstract: Elevated mammalian target of rapamycin (mTOR) signaling contributes to the pathogenesis of diabetes, with increased morbidity and mortality, mainly because of cardiovascular complications. Because mTOR inhibition with rapamycin protects against ischemia/reperfusion injury, we hypothesized that rapamycin would prevent cardiac dysfunction associated with type 2 diabetes (T2D). We also investigated the possible mechanisms and novel protein targets involved in rapamycin-induced preservation of cardiac function in T2D mice. Adult male leptin receptor null, homozygous db/db, or wild type mice were treated daily for 28 days with vehicle (5% DMSO) or rapamycin (0.25 mg/kg, intraperitoneally). Cardiac function was monitored by echocardiography, and protein targets were identified by proteomics analysis. Rapamycin treatment significantly reduced body weight, heart weight, plasma glucose, triglyceride, and insulin levels in db/db mice. Fractional shortening was improved by rapamycin treatment in db/db mice. Oxidative stress as measured by glutathione levels and lipid peroxidation was significantly reduced in rapamycin-treated db/db hearts. Rapamycin blocked the enhanced phosphorylation of mTOR and S6, but not AKT in db/db hearts. Proteomic (by two-dimensional gel and mass spectrometry) and Western blot analyses identified significant changes in several cytoskeletal/contractile proteins (myosin light chain MLY2, myosin heavy chain 6, myosin-binding protein C), glucose metabolism proteins (pyruvate dehydrogenase E1, PYGB, Pgm2), and antioxidant proteins (peroxiredoxin 5, ferritin heavy chain 1) following rapamycin treatment in db/db heart. These results show that chronic rapamycin treatment prevents cardiac dysfunction in T2D mice, possibly through attenuation of oxidative stress and alteration of antioxidants and contractile as well as glucose metabolic protein expression.
authors.affiliation: From the Pauley Heart Center, Division of Cardiology, Virginia Commonwealth University, Richmond, Virginia 23298.
authors.forename: Anindita
authors.initials: A
authors.lastname: Das
authors.forename: David
authors.initials: D
authors.lastname: Durrant
authors.forename: Saisudha
authors.initials: S
authors.lastname: Koka
authors.forename: Fadi N
authors.initials: FN
authors.lastname: Salloum
authors.forename: Lei
authors.initials: L
authors.lastname: Xi
authors.forename: Rakesh C
authors.initials: RC
authors.lastname: Kukreja
mesh_terms: D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology*; D003285:Contractile Proteins / Q000096:biosynthesis* / Q000235:genetics; D003924:Diabetes Mellitus, Type 2 / Q000235:genetics / Q000378:metabolism* / Q000503:physiopathology; D005786:Gene Expression Regulation / Q000187:drug effects*; D005947:Glucose / Q000235:genetics / Q000378:metabolism; D008297:Male; D051379:Mice; D008817:Mice, Mutant Strains; D009200:Myocardial Contraction / Q000187:drug effects*; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology; D018384:Oxidative Stress / Q000187:drug effects*; D040901:Proteomics; D020123:Sirolimus / Q000493:pharmacokinetics*; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D003285:Contractile Proteins; C546842:MTOR protein, human; D058570:TOR Serine-Threonine Kinases; D005947:Glucose; D020123:Sirolimus
keywords: Antioxidants; Cardiovascular Disease; Diabetes; Oxidative Stress; Proteomics; mTOR