title: Heart failure-inducible gene therapy targeting protein phosphatase 1 prevents progressive left ventricular remodeling.
abstract: BACKGROUND
  The targeting of Ca(2+) cycling has emerged as a potential therapy for the treatment of severe heart failure. These approaches include gene therapy directed at overexpressing sarcoplasmic reticulum (SR) Ca(2+) ATPase, or ablation of phospholamban (PLN) and associated protein phosphatase 1 (PP1) protein complexes. We previously reported that PP1β, one of the PP1 catalytic subunits, predominantly suppresses Ca(2+) uptake in the SR among the three PP1 isoforms, thereby contributing to Ca(2+) downregulation in failing hearts. In the present study, we investigated whether heart-failure-inducible PP1β-inhibition by adeno-associated viral-9 (AAV9) vector mediated gene therapy is beneficial for preventing disease progression in genetic cardiomyopathic mice.
  
  
  METHODS
  We created an adeno-associated virus 9 (AAV9) vector encoding PP1β short-hairpin RNA (shRNA) or negative control (NC) shRNA. A heart failure inducible gene expression system was employed using the B-type natriuretic protein (BNP) promoter conjugated to emerald-green fluorescence protein (EmGFP) and the shRNA sequence. AAV9 vectors (AAV9-BNP-EmGFP-PP1βshRNA and AAV9-BNP-EmGFP-NCshRNA) were injected into the tail vein (2×10(11) GC/mouse) of muscle LIM protein deficient mice (MLPKO), followed by serial analysis of echocardiography, hemodynamic measurement, biochemical and histological analysis at 3 months.
  
  
  RESULTS
  In the MLPKO mice, BNP promoter activity was shown to be increased by detecting both EmGFP expression and the induced reduction of PP1β by 25% in the myocardium. Inducible PP1βshRNA delivery preferentially ameliorated left ventricular diastolic function and mitigated adverse ventricular remodeling. PLN phosphorylation was significantly augmented in the AAV9-BNP-EmGFP-PP1βshRNA injected hearts compared with the AAV9-BNP-EmGFP-NCshRNA group. Furthermore, BNP production was reduced, and cardiac interstitial fibrosis was abrogated at 3 months.
  
  
  CONCLUSIONS
  Heart failure-inducible molecular targeting of PP1β has potential as a novel therapeutic strategy for heart failure.
authors.affiliation: Department of Medicine and Clinical Science, Division of Cardiology, Yamaguchi University Graduate School of Medicine, Ube, Japan.
authors.forename: Yosuke
authors.initials: Y
authors.lastname: Miyazaki
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Ikeda
authors.forename: Kozo
authors.initials: K
authors.lastname: Shiraishi
authors.forename: Shizuka N
authors.initials: SN
authors.lastname: Fujimoto
authors.forename: Hidekazu
authors.initials: H
authors.lastname: Aoyama
authors.forename: Koichi
authors.initials: K
authors.lastname: Yoshimura
authors.forename: Makoto
authors.initials: M
authors.lastname: Inui
authors.forename: Masahiko
authors.initials: M
authors.lastname: Hoshijima
authors.forename: Hideko
authors.initials: H
authors.lastname: Kasahara
authors.forename: Hiroki
authors.initials: H
authors.lastname: Aoki
authors.forename: Masunori
authors.initials: M
authors.lastname: Matsuzaki
mesh_terms: D000818:Animals; D020013:Calcium Signaling / Q000235:genetics; D002135:Calcium-Binding Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D009202:Cardiomyopathies / Q000235:genetics / Q000378:metabolism / Q000628:therapy; D000229:Dependovirus / Q000235:genetics*; D015870:Gene Expression; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors; D049452:Green Fluorescent Proteins / Q000235:genetics; D006333:Heart Failure / Q000235:genetics / Q000378:metabolism / Q000628:therapy*; D007527:Isoenzymes / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism; D051379:Mice; D018345:Mice, Knockout; D009206:Myocardium / Q000378:metabolism* / Q000473:pathology; D020097:Natriuretic Peptide, Brain / Q000235:genetics; D011401:Promoter Regions, Genetic; D054645:Protein Phosphatase 1 / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases / Q000378:metabolism; D020257:Ventricular Remodeling / Q000235:genetics*; D000099211:Phospholamban
chemical_list: D002135:Calcium-Binding Proteins; D049452:Green Fluorescent Proteins; D007527:Isoenzymes; D020097:Natriuretic Peptide, Brain; D054645:Protein Phosphatase 1; D034741:RNA, Small Interfering; D053498:Sarcoplasmic Reticulum Calcium-Transporting ATPases; D000099211:Phospholamban