title: Hydrogen peroxide-induced poly(ADP-ribosyl)ation regulates osteogenic differentiation-associated cell death.
abstract: We set out to investigate the role of poly(ADP-ribosylation), the attachment of NAD(+)-derived (ADP-ribose)(n) polymers to proteins, in the regulation of osteogenic differentiation of SAOS-2 cells and mesenchymal stem cells. In osteogenic differentiation medium, SAOS-2 cells showed mineralization and expressed alkaline phosphatase and osteoblastic marker genes such as Runx2, osterix, BMP2, and osteopontin. The cells also released hydrogen peroxide, displayed poly(ADP-ribose) polymerase (PARP) activation, and showed commitment to cell death (apoptosis and necrosis). Scavenging reactive oxygen species by glutathione or decomposing hydrogen peroxide by the addition of catalase reduced differentiation, PARP activation, and cell death. We silenced the expression of the main PAR-synthesizing enzyme PARP-1 and the PAR-degrading enzyme poly(ADP-ribose) glycohydrolase (PARG) in SAOS-2 osteosarcoma cells (shPARP-1 and shPARG, respectively). Both shPARP-1- and shPARG-silenced cells exhibited altered differentiation, with the most notable change being increased osteopontin expression but decreased alkaline phosphatase activity. PARP-1 silencing suppressed both apoptotic and necrotic cell death, but the PARP inhibitor PJ34 sensitized cells to cell death, indicating that the effects of PARP-1 silencing are not related to the activity of the enzyme. PARG silencing resulted in more apoptosis and, in the last days of differentiation, a shift from apoptosis toward necrosis. In conclusion our data prove that hydrogen peroxide-induced poly(ADP-ribose) signaling regulates cell death and osteodifferentiation.
authors.affiliation: Department of Medical Chemistry, Medical and Health Science Center, University of Debrecen, H-4032 Debrecen, Hungary.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Robaszkiewicz
authors.forename: Katalin
authors.initials: K
authors.lastname: Erdélyi
authors.forename: Katalin
authors.initials: K
authors.lastname: Kovács
authors.forename: István
authors.initials: I
authors.lastname: Kovács
authors.forename: Péter
authors.initials: P
authors.lastname: Bai
authors.forename: Eva
authors.initials: E
authors.lastname: Rajnavölgyi
authors.forename: László
authors.initials: L
authors.lastname: Virág
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D015153:Blotting, Western; D001859:Bone Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D002454:Cell Differentiation / Q000187:drug effects*; D049109:Cell Proliferation / Q000187:drug effects; D002478:Cells, Cultured; D002823:Chorion; D005260:Female; D006026:Glycoside Hydrolases / Q000235:genetics / Q000378:metabolism; D006801:Humans; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D059630:Mesenchymal Stem Cells; D010012:Osteogenesis / Q000187:drug effects*; D012516:Osteosarcoma / Q000235:genetics / Q000378:metabolism / Q000473:pathology*; D016877:Oxidants / Q000494:pharmacology; D018384:Oxidative Stress / Q000187:drug effects; D010920:Placenta; D011064:Poly Adenosine Diphosphate Ribose / Q000378:metabolism*; D011065:Poly(ADP-ribose) Polymerases / Q000235:genetics / Q000378:metabolism; D011247:Pregnancy; D012333:RNA, Messenger / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D016877:Oxidants; D012333:RNA, Messenger; D011064:Poly Adenosine Diphosphate Ribose; D006861:Hydrogen Peroxide; D011065:Poly(ADP-ribose) Polymerases; D006026:Glycoside Hydrolases; C022407:poly ADP-ribose glycohydrolase