title: MicroRNA-21 Lowers Blood Pressure in Spontaneous Hypertensive Rats by Upregulating Mitochondrial Translation.
abstract: Excessive reactive oxygen species generated in mitochondria has been implicated as a causal event in hypertensive cardiomyopathy. Multiple recent studies suggest that microRNAs (miRNAs) are able to translocate to mitochondria to modulate mitochondrial activities, but the medical significance of such a new miRNA function has remained unclear. Here, we characterized spontaneous hypertensive rats (SHRs) in comparison with Wistar rats, finding that micro RNA-21 (miR-21) was dramatically induced in SHRs relative to Wistar rats. We designed a series of experiments to determine whether miR-21 is involved in regulating reactive oxygen species generation in mitochondria, and if so, how induced miR-21 may either contribute to hypertensive cardiomyopathy or represent a compensatory response.
  
  
  
  Western blotting was used to compare the expression of key nuclear genome (nDNA)-encoded and mitochondrial genome (mtDNA)-encoded genes involved in reactive oxygen species production in SHRs and Wistar rats. Bioinformatics was used to predict miRNA targets followed by biochemical validation using quantitative real-time polymerase chain reaction and Ago2 immunoprecipitation. The direct role of miRNA in mitochondria was determined by GW182 dependence, which is required for miRNA to function in the cytoplasm, but not in mitochondria. Recombinant adeno-associated virus (type 9) was used to deliver miRNA mimic to rats via tail vein, and blood pressure was monitored with a photoelectric tail-cuff system. Cardiac structure and functions were assessed by echocardiography and catheter manometer system.
  
  
  
  We observed a marked reduction of mtDNA-encoded cytochrome b (mt-Cytb) in the heart of SHRs. Downregulation of mt-Cytb by small interfering RNA in mitochondria recapitulates some key disease features, including elevated reactive oxygen species production. Computational prediction coupled with biochemical analysis revealed that miR-21 directly targeted mt-Cytb to positively modulate mt-Cytb translation in mitochondria. Circulating miR-21 levels in hypertensive patients were significantly higher than those in controls, showing a positive correlation between miR-21 expression and blood pressure. Remarkably, recombinant adeno-associated virus-mediated delivery of miR-21 was sufficient to reduce blood pressure and attenuate cardiac hypertrophy in SHRs.
  
  
  
  Our findings reveal a positive function of miR-21 in mitochondrial translation, which is sufficient to reduce blood pressure and alleviate cardiac hypertrophy in SHRs. This observation indicates that induced miR-21 is part of the compensatory program and suggests a novel theoretical ground for developing miRNA-based therapeutics against hypertension.
authors.affiliation: From Division of Cardiology, Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China (H.L., F.W., L.Z., Z.Y., J.F., X.N., P.W., C.C., D.W.W.); Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China (X.Z., X.-D.F.); and Department of Cellular and Molecular Medicine and Institute of Genomic Medicine, University of California, San Diego, La Jolla (X.-D.F.).
authors.forename: Huaping
authors.initials: H
authors.lastname: Li
authors.affiliation: From Division of Cardiology, Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China (H.L., F.W., L.Z., Z.Y., J.F., X.N., P.W., C.C., D.W.W.); Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China (X.Z., X.-D.F.); and Department of Cellular and Molecular Medicine and Institute of Genomic Medicine, University of California, San Diego, La Jolla (X.-D.F.).
authors.forename: Xiaorong
authors.initials: X
authors.lastname: Zhang
authors.affiliation: From Division of Cardiology, Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China (H.L., F.W., L.Z., Z.Y., J.F., X.N., P.W., C.C., D.W.W.); Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China (X.Z., X.-D.F.); and Department of Cellular and Molecular Medicine and Institute of Genomic Medicine, University of California, San Diego, La Jolla (X.-D.F.).
authors.forename: Feng
authors.initials: F
authors.lastname: Wang
authors.affiliation: From Division of Cardiology, Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China (H.L., F.W., L.Z., Z.Y., J.F., X.N., P.W., C.C., D.W.W.); Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China (X.Z., X.-D.F.); and Department of Cellular and Molecular Medicine and Institute of Genomic Medicine, University of California, San Diego, La Jolla (X.-D.F.).
authors.forename: Ling
authors.initials: L
authors.lastname: Zhou
authors.affiliation: From Division of Cardiology, Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China (H.L., F.W., L.Z., Z.Y., J.F., X.N., P.W., C.C., D.W.W.); Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China (X.Z., X.-D.F.); and Department of Cellular and Molecular Medicine and Institute of Genomic Medicine, University of California, San Diego, La Jolla (X.-D.F.).
authors.forename: Zhongwei
authors.initials: Z
authors.lastname: Yin
authors.affiliation: From Division of Cardiology, Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China (H.L., F.W., L.Z., Z.Y., J.F., X.N., P.W., C.C., D.W.W.); Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China (X.Z., X.-D.F.); and Department of Cellular and Molecular Medicine and Institute of Genomic Medicine, University of California, San Diego, La Jolla (X.-D.F.).
authors.forename: Jiahui
authors.initials: J
authors.lastname: Fan
authors.affiliation: From Division of Cardiology, Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China (H.L., F.W., L.Z., Z.Y., J.F., X.N., P.W., C.C., D.W.W.); Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China (X.Z., X.-D.F.); and Department of Cellular and Molecular Medicine and Institute of Genomic Medicine, University of California, San Diego, La Jolla (X.-D.F.).
authors.forename: Xiang
authors.initials: X
authors.lastname: Nie
authors.affiliation: From Division of Cardiology, Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China (H.L., F.W., L.Z., Z.Y., J.F., X.N., P.W., C.C., D.W.W.); Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China (X.Z., X.-D.F.); and Department of Cellular and Molecular Medicine and Institute of Genomic Medicine, University of California, San Diego, La Jolla (X.-D.F.).
authors.forename: Peihua
authors.initials: P
authors.lastname: Wang
authors.affiliation: From Division of Cardiology, Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China (H.L., F.W., L.Z., Z.Y., J.F., X.N., P.W., C.C., D.W.W.); Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China (X.Z., X.-D.F.); and Department of Cellular and Molecular Medicine and Institute of Genomic Medicine, University of California, San Diego, La Jolla (X.-D.F.).
authors.forename: Xiang-Dong
authors.initials: XD
authors.lastname: Fu
authors.affiliation: From Division of Cardiology, Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China (H.L., F.W., L.Z., Z.Y., J.F., X.N., P.W., C.C., D.W.W.); Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China (X.Z., X.-D.F.); and Department of Cellular and Molecular Medicine and Institute of Genomic Medicine, University of California, San Diego, La Jolla (X.-D.F.). chenchen@tjh.tjmu.edu.cn dwwang@tjh.tjmu.edu.cn.
authors.forename: Chen
authors.initials: C
authors.lastname: Chen
authors.affiliation: From Division of Cardiology, Department of Internal Medicine, Tongji Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, China (H.L., F.W., L.Z., Z.Y., J.F., X.N., P.W., C.C., D.W.W.); Key Laboratory of RNA Biology, Institute of Biophysics, Chinese Academy of Sciences, Beijing, China (X.Z., X.-D.F.); and Department of Cellular and Molecular Medicine and Institute of Genomic Medicine, University of California, San Diego, La Jolla (X.-D.F.). chenchen@tjh.tjmu.edu.cn dwwang@tjh.tjmu.edu.cn.
authors.forename: Dao Wen
authors.initials: DW
authors.lastname: Wang
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D006973:Hypertension / Q000188:drug therapy / Q000378:metabolism*; D008297:Male; D035683:MicroRNAs / Q000235:genetics / Q000494:pharmacology / Q000627:therapeutic use*; D008928:Mitochondria / Q000187:drug effects / Q000235:genetics / Q000378:metabolism*; D051381:Rats; D011918:Rats, Inbred SHR; D017208:Rats, Wistar; D017382:Reactive Oxygen Species / Q000378:metabolism; D015533:Transcriptional Activation / Q000187:drug effects / Q000502:physiology*; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology*
chemical_list: D035683:MicroRNAs; D017382:Reactive Oxygen Species; C546082:mirn21 microRNA, rat
keywords: MIR-21 microRNA, human; cytochrome b; mitochondria; reactive oxygen species