title: Timed regulation of P-element-induced wimpy testis-interacting RNA expression during rat liver regeneration.
abstract: Small noncoding RNAs comprise a growing family of molecules that regulate key cellular processes, including messenger RNA (mRNA) degradation, translational repression, and transcriptional gene silencing. P-element-induced wimpy testis (PIWI)-interacting RNAs (piRNAs) represent a class of small RNAs initially identified in the germline of a variety of species, where they contribute to maintenance of genome stability, and recently found expressed also in stem and somatic cells, where their role and responsiveness to physiopathological signals remain elusive. Here, we investigated piRNA expression in rat liver and its response to the stimuli exerted by regenerative proliferation of this organ. Quantitative polymerase chain reaction analysis identify in the liver the RNAs encoding PIWIL2/HILI, PIWIL4/HIWI2, and other components of the piRNA biogenesis pathways, suggesting that this is indeed functional. RNA sequencing before, during, and after the wave of cell proliferation that follows partial hepatectomy (PH) identified ∼1,400 mammalian germline piRNAs expressed in rat liver, including 72 showing timed changes in expression 24-48 hours post-PH, a timing that corresponds to cell transition through the S phase, returning to basal levels by 168 hours, when organ regeneration is completed and hepatocytes reach quiescence.
  
  
  CONCLUSIONS
  The piRNA pathway is active in somatic cells of the liver and is subject to regulation during the pathophysiological process of organ regeneration, when these molecules are available to exert their regulatory functions on the cell genome and transcriptome, as demonstrated by the identification of several liver mRNAs representing candidate targets of these regulatory RNAs.
authors.affiliation: Laboratory of Molecular Medicine and Genomics, Department of Medicine and Surgery, University of Salerno, Baronissi, Italy.
authors.forename: Francesca
authors.initials: F
authors.lastname: Rizzo
authors.forename: Adnan
authors.initials: A
authors.lastname: Hashim
authors.forename: Giovanna
authors.initials: G
authors.lastname: Marchese
authors.forename: Maria
authors.initials: M
authors.lastname: Ravo
authors.forename: Roberta
authors.initials: R
authors.lastname: Tarallo
authors.forename: Giovanni
authors.initials: G
authors.lastname: Nassa
authors.forename: Giorgio
authors.initials: G
authors.lastname: Giurato
authors.forename: Antonio
authors.initials: A
authors.lastname: Rinaldi
authors.forename: Angela
authors.initials: A
authors.lastname: Cordella
authors.forename: Marcello
authors.initials: M
authors.lastname: Persico
authors.forename: Pia
authors.initials: P
authors.lastname: Sulas
authors.forename: Andrea
authors.initials: A
authors.lastname: Perra
authors.forename: Giovanna M
authors.initials: GM
authors.lastname: Ledda-Columbano
authors.forename: Amedeo
authors.initials: A
authors.lastname: Columbano
authors.forename: Alessandro
authors.initials: A
authors.lastname: Weisz
mesh_terms: D000818:Animals; D049109:Cell Proliferation; D015536:Down-Regulation / Q000235:genetics; D005786:Gene Expression Regulation; D006498:Hepatectomy; D008115:Liver Regeneration / Q000235:genetics*; D008297:Male; D011401:Promoter Regions, Genetic; D034741:RNA, Small Interfering / Q000096:biosynthesis* / Q000235:genetics*; D051381:Rats; D011916:Rats, Inbred F344; D017423:Sequence Analysis, RNA
chemical_list: D034741:RNA, Small Interfering