title: Abundant and Altered Expression of PIWI-Interacting RNAs during Cardiac Hypertrophy.
abstract: BACKGROUND
  The discovery of PIWI-interacting RNAs (piRNAs) has fundamentally changed our understanding of post transcriptional regulation of transposons and other genes. Unlike miRNA and siRNA, the piRNAs are the most abundant but least studied RNA species in mammals. Although the expression of PIWI proteins and piRNAs has long been regarded as germline specific, increasing evidences suggest the expression of piRNAs in somatic cells.
  
  
  METHODS
  In this study, the small RNA sequencing executed during induction of cardiac hypertrophy in both in vivo and in vitro conditions were annotated for the expression of piRNAs. The expression of piRNAs was validated by qPCR and RNA immunoprecipitation. In addition, the presence of piRNAs in circulation of myocardial infarction patients was studied by qPCR.
  
  
  RESULTS
  We identified an abundant and altered expression of piRNAs during cardiac hypertrophy. The differentially expressed piRNAs was validated by qPCR and RNA immunoprecipitation. The significantly and differentially expressed piRNAs were predicted to target different retrotransposons and mRNAs in the rat genome. The detection of specific piRNA in serum of myocardial infarction patients suggests the potential of piRNA for diagnosis.
  
  
  CONCLUSIONS
  Overall this study is the first to provide a whole-genome analysis of the large repertoire of piRNAs in the cardiac system and this would pave a new path to understanding the molecular aetiology of piRNA and retrotransposons in the physiology and pathology of the cardiac system.
authors.affiliation: Cardiac Hypertrophy Laboratory, Department of Molecular Biology, School of Biological Sciences, Madurai Kamaraj University, Madurai, 625 021, Tamilnadu, India.
authors.forename: K Shanmugha
authors.initials: KS
authors.lastname: Rajan
authors.affiliation: Cardiac Hypertrophy Laboratory, Department of Molecular Biology, School of Biological Sciences, Madurai Kamaraj University, Madurai, 625 021, Tamilnadu, India.
authors.forename: Ganesan
authors.initials: G
authors.lastname: Velmurugan
authors.affiliation: Department of Plant Biotechnology, School of Biotechnology, Madurai Kamaraj University, Madurai, 625 021, Tamilnadu, India.
authors.forename: Pandi
authors.initials: P
authors.lastname: Gopal
authors.affiliation: Center for Molecular and Translational Medicine, Georgia State University, Atlanta, GA, USA.
authors.forename: Tharmarajan
authors.initials: T
authors.lastname: Ramprasath
authors.affiliation: Cardiac Hypertrophy Laboratory, Department of Molecular Biology, School of Biological Sciences, Madurai Kamaraj University, Madurai, 625 021, Tamilnadu, India.
authors.forename: D D Venkatesh
authors.initials: DD
authors.lastname: Babu
authors.affiliation: Department of Plant Biotechnology, School of Biotechnology, Madurai Kamaraj University, Madurai, 625 021, Tamilnadu, India.
authors.forename: S
authors.initials: S
authors.lastname: Krithika
authors.affiliation: Cardiac Hypertrophy Laboratory, Department of Molecular Biology, School of Biological Sciences, Madurai Kamaraj University, Madurai, 625 021, Tamilnadu, India.
authors.forename: Y Christy
authors.initials: YC
authors.lastname: Jenifer
authors.affiliation: Deparment of Zoology, Madras Christian College, Chennai, 600 059, Tamilnadu, India.
authors.forename: Allen
authors.initials: A
authors.lastname: Freddy
authors.affiliation: Department of Clinical & Experimental Medicine, University Linkoping, Linkoping, Sweden.
authors.forename: George
authors.initials: G
authors.lastname: William
authors.affiliation: Department of Plant Pathology, Regional Research Station, Tamilnadu Agricultural University, Krishangiri, Tamilnadu, India.
authors.forename: Krishnan
authors.initials: K
authors.lastname: Kalpana
authors.affiliation: Cardiac Hypertrophy Laboratory, Department of Molecular Biology, School of Biological Sciences, Madurai Kamaraj University, Madurai, 625 021, Tamilnadu, India. Electronic address: subbiahr@nrcbsmku.org.
authors.forename: Subbiah
authors.initials: S
authors.lastname: Ramasamy
mesh_terms: D000818:Animals; D006332:Cardiomegaly / Q000378:metabolism*; D005786:Gene Expression Regulation; D055106:Genome-Wide Association Study; D034741:RNA, Small Interfering / Q000096:biosynthesis*; D051381:Rats
chemical_list: D034741:RNA, Small Interfering
keywords: Cardiac hypertrophy; Retrotransposons; Small RNA deep sequencing; Small non-coding RNA; piRNA