title: A synthetic double-stranded RNA, poly I:C, induces a rapid apoptosis of human CD34(+) cells.
abstract: Toll-like receptor 3 (TLR3), retinoic acid-inducible gene I, and melanoma differentiation-associated antigen 5 (RIG-I/MDA-5) helicases are known to sense double-stranded RNA (dsRNA) virus and initiate antiviral responses, such as production of type-I interferons (IFNs). Recognition of dsRNA by TLR3 or RIG-I/MDA-5 is cell-type-dependent and recent studies have shown a direct link between TLRs and hematopoiesis. We hypothesized that viral dsRNA recognized by either TLR3 or RIG-I/MDA-5, affects the growth of human hematopoietic stem/progenitor cells. Here we show that polyinosinic polycytidylic acid (poly I:C)-mediated very rapid apoptosis occurs within 1 hour in CD34(+) cells in a dose-dependent manner. Polyadenylic-polyuridylic acid, another synthetic dsRNA that signals only through TLR3, had no effect. Poly I:C-LMW/LyoVec, a complex between low molecular-weight poly I:C and the transfection reagent LyoVec, which signals only through RIG-I/MDA-5, induces apoptosis of CD34(+) cells. A strong and sustained upregulation of messenger RNA and protein levels of Noxa, a proapoptotic BH3-only protein that can be induced by RIG-I/MDA-5 pathway, is found in CD34(+) cells treated by poly I:C. Although poly I:C upregulates type-I IFNs in CD34(+) cells, neither exogenous IFN-α nor IFN-β induces rapid apoptosis in CD34(+) cells and neutralization or blocking of type-I IFN receptor does not rescue CD34(+) cells, whereas Z-VAD, a pan-caspase inhibitor, rescues the cells from apoptosis. These results suggest that RIG-I/MDA-5, but not TLR3, signaling triggers poly I:C-induced rapid apoptosis of human CD34(+) cells, which will provide an insight into the mechanisms of dsRNA virus-mediated hematopoietic disorders.
authors.affiliation: Department of Hematology, Nephrology, and Rheumatology, Akita University Graduate School of Medicine, Akita, Japan.
authors.forename: Jiajia
authors.initials: J
authors.lastname: Liu
authors.forename: Yong-Mei
authors.initials: YM
authors.lastname: Guo
authors.forename: Makoto
authors.initials: M
authors.lastname: Hirokawa
authors.forename: Keiko
authors.initials: K
authors.lastname: Iwamoto
authors.forename: Kumi
authors.initials: K
authors.lastname: Ubukawa
authors.forename: Yoshihiro
authors.initials: Y
authors.lastname: Michishita
authors.forename: Naohito
authors.initials: N
authors.lastname: Fujishima
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Tagawa
authors.forename: Naoto
authors.initials: N
authors.lastname: Takahashi
authors.forename: Weiguo
authors.initials: W
authors.lastname: Xiao
authors.forename: Junsuke
authors.initials: J
authors.lastname: Yamashita
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Ohteki
authors.forename: Kenichi
authors.initials: K
authors.lastname: Sawada
mesh_terms: D017209:Apoptosis / Q000187:drug effects*; D020169:Caspases / Q000502:physiology; D019070:Cell Lineage; D002478:Cells, Cultured / Q000166:cytology / Q000187:drug effects; D015853:Cysteine Proteinase Inhibitors / Q000494:pharmacology; D000071457:DEAD Box Protein 58; D053487:DEAD-box RNA Helicases / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D006410:Hematopoiesis / Q000187:drug effects; D006412:Hematopoietic Stem Cells / Q000166:cytology / Q000187:drug effects*; D006801:Humans; D000072640:Interferon-Induced Helicase, IFIH1; D016898:Interferon-alpha / Q000494:pharmacology; D016899:Interferon-beta / Q000494:pharmacology; D008970:Molecular Weight; D009838:Oligodeoxyribonucleotides / Q000494:pharmacology; D009842:Oligopeptides / Q000494:pharmacology; D011063:Poly A-U / Q000494:pharmacology; D011070:Poly I-C / Q000008:administration & dosage / Q000494:pharmacology*; D019253:Proto-Oncogene Proteins c-bcl-2 / Q000096:biosynthesis / Q000235:genetics; D012333:RNA, Messenger / Q000096:biosynthesis; D011971:Receptors, Immunologic; D017471:Receptors, Interferon / Q000037:antagonists & inhibitors; D051196:Toll-Like Receptor 3 / Q000502:physiology; D015854:Up-Regulation
chemical_list: D015853:Cysteine Proteinase Inhibitors; D016898:Interferon-alpha; D009838:Oligodeoxyribonucleotides; D009842:Oligopeptides; C498702:PMAIP1 protein, human; D019253:Proto-Oncogene Proteins c-bcl-2; D012333:RNA, Messenger; D011971:Receptors, Immunologic; D017471:Receptors, Interferon; C495344:TLR3 protein, human; D051196:Toll-Like Receptor 3; C517629:benzyloxycarbonyl-valyl-alanyl-aspartic acid; D011063:Poly A-U; D016899:Interferon-beta; D020169:Caspases; C452820:RIGI protein, human; C452815:IFIH1 protein, human; D000071457:DEAD Box Protein 58; D053487:DEAD-box RNA Helicases; D000072640:Interferon-Induced Helicase, IFIH1; D011070:Poly I-C