A synthetic double-stranded RNA, poly I:C, induces a rapid apoptosis of human CD34(+) cells

Exp Hematol. 2012 Apr;40(4):330-41. doi: 10.1016/j.exphem.2011.12.002. Epub 2011 Dec 20.

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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Apoptosis / drug effects*
  • Caspases / physiology
  • Cell Lineage
  • Cells, Cultured / cytology
  • Cells, Cultured / drug effects
  • Cysteine Proteinase Inhibitors / pharmacology
  • DEAD Box Protein 58
  • DEAD-box RNA Helicases / physiology
  • Dose-Response Relationship, Drug
  • Hematopoiesis / drug effects
  • Hematopoietic Stem Cells / cytology
  • Hematopoietic Stem Cells / drug effects*
  • Humans
  • Interferon-Induced Helicase, IFIH1
  • Interferon-alpha / pharmacology
  • Interferon-beta / pharmacology
  • Molecular Weight
  • Oligodeoxyribonucleotides / pharmacology
  • Oligopeptides / pharmacology
  • Poly A-U / pharmacology
  • Poly I-C / administration & dosage
  • Poly I-C / pharmacology*
  • Proto-Oncogene Proteins c-bcl-2 / biosynthesis
  • Proto-Oncogene Proteins c-bcl-2 / genetics
  • RNA, Messenger / biosynthesis
  • Receptors, Immunologic
  • Receptors, Interferon / antagonists & inhibitors
  • Toll-Like Receptor 3 / physiology
  • Up-Regulation

Substances

  • Cysteine Proteinase Inhibitors
  • Interferon-alpha
  • Oligodeoxyribonucleotides
  • Oligopeptides
  • PMAIP1 protein, human
  • Proto-Oncogene Proteins c-bcl-2
  • RNA, Messenger
  • Receptors, Immunologic
  • Receptors, Interferon
  • TLR3 protein, human
  • Toll-Like Receptor 3
  • benzyloxycarbonyl-valyl-alanyl-aspartic acid
  • Poly A-U
  • Interferon-beta
  • Caspases
  • RIGI protein, human
  • IFIH1 protein, human
  • DEAD Box Protein 58
  • DEAD-box RNA Helicases
  • Interferon-Induced Helicase, IFIH1
  • Poly I-C