Correction: A Novel Artificial MicroRNA Expressing AAV Vector for Phospholamban Silencing in Cardiomyocytes Improves Ca2+ Uptake into the Sarcoplasmic Reticulum

In failing rat hearts, post-transcriptonal inhibition of phospholamban (PLB) expression by AAV9 vector-mediated cardiac delivery of short hairpin RNAs directed against PLB (shPLBr) improves both impaired SERCA2a controlled Ca cycling and contractile dysfunction. Cardiac delivery of shPLB, however, was reported to cause cardiac toxicity in canines. Thus we developed a new AAV vector, scAAV6-amiR155-PLBr, expressing a novel engineered artificial microRNA (amiR155-PLBr) directed against PLB under control of a heart-specific hybrid promoter. Its PLB silencing efficiency and safety were compared with those of an AAV vector expressing shPLBr (scAAV6-shPLBr) from an ubiquitously active U6 promoter. Investigations were carried out in cultured neonatal rat cardiomyocytes (CM) over a period of 14 days. Compared to shPLBr, amiR155-PLBr was expressed at a significantly lower level, resulting in delayed and less pronounced PLB silencing. Despite decreased knockdown efficiency of scAAV6-amiR155-PLBr, a similar increase of the SERCA2a-catalyzed Ca uptake into sarcoplasmic reticulum (SR) vesicles was observed for both the shPLBr and amiR155-PLBr vectors. Proteomic analysis confirmed PLB silencing of both therapeutic vectors and revealed that shPLBr, but not the amiR155-PLBr vector, increased the proinflammatory proteins STAT3, STAT1 and activated STAT1 phosphorylation at the key amino acid residue Tyr701. Quantitative RT-PCR analysis detected alterations in the expression of several cardiac microRNAs after treatment of CM with scAAV6-shPLBr and scAAV6-amiR155-PLBr, as well as after treatment with its related amiR155and shRNAs-expressing control AAV vectors. The results demonstrate that scAAV6-amiR155-PLBr is capable of enhancing the Ca transport function of the cardiac SR PLB/SERCA2a system as efficiently as scAAV6-shPLBr while offering a superior safety profile. Citation: Gröbl T, Hammer E, Bien-Möller S, Geisler A, Pinkert S, et al. (2014) A Novel Artificial MicroRNA Expressing AAV Vector for Phospholamban Silencing in Cardiomyocytes Improves Ca Uptake into the Sarcoplasmic Reticulum. PLoS ONE 9(3): e92188. doi:10.1371/journal.pone. 0092188 Editor: R. Jude Samulski, University of North Carolina at Chapel Hill, United States of America Received September 12, 2013; Accepted February 19, 2014; Published March 26, 2014 Copyright: 2014 Gröbl et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. Funding: This work was supported by the Deutsche Forschungsgemeinschaft through SFB Transregio 19 project grants to HF, UV and RV. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: HF and JK submitted a patent application entitled ‘‘Polynucleotide sequence for the inhibition of phospholamban synthesis’’ (Patent application number: 20100310521, Publication date: 2010-12-09). HF and WP submitted a patent application entitled ‘‘RNA Interference for the Treatment of Heart Failure’’ (Patent application number: 20110098338, Publication date: 2011-04-28). This does not alter adherence to all the PLOS ONE policies on sharing data and materials, as detailed online in the guide for authors of PLOS ONE. * E-mail: henry.fechner@tu-berlin.de . These authors contributed equally to this work.