title: Expression and Regulation of PIWIL-Proteins and PIWI-Interacting RNAs in Rheumatoid Arthritis.
abstract: OBJECTIVE
  The PIWIL (P-element induced wimpy testis like protein) subfamily of argonaute proteins is essential for Piwi-interacting RNA (piRNA) biogenesis and their function to silence transposons during germ-line development. Here we explored their presence and regulation in rheumatoid arthritis (RA).
  
  
  METHODS
  The expression of PIWIL genes in RA and osteoarthritis (OA) synovial tissues and synovial fibroblasts (SF) was analysed by Real-time PCR, immunofluorescence and Western blot. The expression of piRNAs was quantified by next generation small RNA sequencing (NGS). The regulation of PIWI/piRNAs, proliferation and methylation of LINE-1 after silencing of PIWIL genes were studied.
  
  
  RESULTS
  PIWIL2 and 4 mRNA were similarly expressed in synovial tissues and SF from RA and OA patients. However, on the protein level only PIWIL4 was strongly expressed in SF. Using NGS up to 300 piRNAs were identified in all SF without significant differences in expression levels between RA and OASF. Of interest, the analysis of the co-expression of the detected piRNAs revealed a less tightly regulated pattern of piRNA-823, -4153 and -16659 expression in RASF. In RASF and OASF, stimulation with TNFα+IL1β/TLR-ligands further significantly increased the expression levels of PIWIL2 and 4 mRNA and piRNA-16659 was significantly (4-fold) induced upon Poly(I:C) stimulation. Silencing of PIWIL2/4 neither affect LINE-1 methylation/expression nor proliferation of RASF.
  
  
  CONCLUSIONS
  We detected a new class of small regulatory RNAs (piRNAs) and their specific binding partners (PIWIL2/4) in synovial fibroblasts. The differential regulation of co-expression of piRNAs in RASF and the induction of piRNA/Piwi-proteins by innate immune stimulators suggest a role in inflammatory processes.
authors.affiliation: Center of Experimental Rheumatology, University Hospital Zürich, Zürich, Switzerland.
authors.forename: Lenka
authors.initials: L
authors.lastname: Pleštilová
authors.affiliation: Center of Experimental Rheumatology, University Hospital Zürich, Zürich, Switzerland.
authors.forename: Michel
authors.initials: M
authors.lastname: Neidhart
authors.affiliation: Functional Genomic Centre Zürich, Zürich, Switzerland.
authors.forename: Giancarlo
authors.initials: G
authors.lastname: Russo
authors.affiliation: Center of Experimental Rheumatology, University Hospital Zürich, Zürich, Switzerland.
authors.forename: Mojca
authors.initials: M
authors.lastname: Frank-Bertoncelj
authors.affiliation: Center of Experimental Rheumatology, University Hospital Zürich, Zürich, Switzerland.
authors.forename: Caroline
authors.initials: C
authors.lastname: Ospelt
authors.affiliation: Department of Rheumatology, University Hospital Zürich, Zürich, Switzerland.
authors.forename: Adrian
authors.initials: A
authors.lastname: Ciurea
authors.affiliation: Schulthess Clinic, Zürich, Switzerland.
authors.forename: Christoph
authors.initials: C
authors.lastname: Kolling
authors.affiliation: Center of Experimental Rheumatology, University Hospital Zürich, Zürich, Switzerland.
authors.forename: Renate E
authors.initials: RE
authors.lastname: Gay
authors.affiliation: Department of Rheumatology, University Hospital Zürich, Zürich, Switzerland.
authors.forename: Beat A
authors.initials: BA
authors.lastname: Michel
authors.affiliation: Institute of Rheumatology and Clinic of Rheumatology, 1st Faculty of Medicine, Charles University in Prague, Prague, Czech Republic.
authors.forename: Jiří
authors.initials: J
authors.lastname: Vencovský
authors.affiliation: Center of Experimental Rheumatology, University Hospital Zürich, Zürich, Switzerland.
authors.forename: Steffen
authors.initials: S
authors.lastname: Gay
authors.affiliation: Center of Experimental Rheumatology, University Hospital Zürich, Zürich, Switzerland.
authors.forename: Astrid
authors.initials: A
authors.lastname: Jüngel
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D060565:Argonaute Proteins / Q000235:genetics / Q000378:metabolism; D001172:Arthritis, Rheumatoid / Q000235:genetics* / Q000378:metabolism / Q000473:pathology; D016207:Cytokines / Q000378:metabolism; D005260:Female; D005347:Fibroblasts / Q000473:pathology; D005786:Gene Expression Regulation; D006801:Humans; D020084:Long Interspersed Nucleotide Elements; D008297:Male; D008875:Middle Aged; D010003:Osteoarthritis / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D011506:Proteins / Q000235:genetics / Q000378:metabolism; D034741:RNA, Small Interfering / Q000378:metabolism*; D016601:RNA-Binding Proteins; D013583:Synovial Membrane / Q000473:pathology
chemical_list: D060565:Argonaute Proteins; D016207:Cytokines; C486868:PIWIL2 protein, human; C556794:PIWIL3 protein, human; C556795:PIWIL4 protein, human; D011506:Proteins; D034741:RNA, Small Interfering; D016601:RNA-Binding Proteins