Identification of 2'-phosphodiesterase, which plays a role in the 2-5A system regulated by interferon

J Biol Chem. 2004 Sep 3;279(36):37832-41. doi: 10.1074/jbc.M400089200. Epub 2004 Jun 30.

Abstract

The 2-5A system is one of the major pathways for antiviral and antitumor functions that can be induced by interferons (IFNs). The 2-5A system is modulated by 5'-triphosphorylated, 2',5'-phosphodiester-linked oligoadenylates (2-5A), which are synthesized by 2',5'-oligoadenylate synthetases (2',5'-OASs), inactivated by 5'-phosphatase and completely degraded by 2'-phosphodiesterase (2'-PDE). Generated 2-5A activates 2-5A-dependent endoribonuclease, RNase L, which induces RNA degradation in cells and finally apoptosis. Although 2',5'-OASs and RNase L have been molecularly cloned and studied well, the identification of 2'-PDE has remained elusive. Here, we describe the first identification of 2'-PDE, the third key enzyme of the 2-5A system. We found a putative 2'-PDE band on SDS-PAGE by successive six-step chromatographies from ammonium sulfate precipitates of bovine liver and identified a partial amino acid sequence of the human 2'-PDE by mass spectrometry. Based on the full-length sequence of the human 2'-PDE obtained by in silico expressed sequence tag assembly, the gene was cloned by reverse transcription-PCR. The recombinant human 2'-PDE expressed in mammalian cells certainly cleaved the 2',5'-phosphodiester bond of 2-5A trimer and 2-5A analogs. Because no sequences with high homology to this human 2'-PDE were found, the human 2'-PDE was considered to be a unique enzyme without isoform. Suppression of 2'-PDE by a small interfering RNA and a 2'-PDE inhibitor resulted in significant reduction of viral replication, whereas overexpression of 2'-PDE protected cells from IFN-induced antiproliferative activity. These observations identify 2'-PDE as a key regulator of the 2-5A system and as a potential novel target for antiviral and antitumor treatments.

MeSH terms

  • Adenine Nucleotides / metabolism*
  • Amino Acid Sequence
  • Animals
  • Base Sequence
  • Cattle
  • DNA Primers
  • Exoribonucleases / antagonists & inhibitors
  • Exoribonucleases / chemistry
  • Exoribonucleases / metabolism*
  • HeLa Cells
  • Humans
  • Liver / enzymology
  • Molecular Sequence Data
  • Oligoribonucleotides / metabolism*
  • Phosphodiesterase Inhibitors / pharmacology
  • Sequence Homology, Amino Acid
  • Virus Replication / drug effects

Substances

  • Adenine Nucleotides
  • DNA Primers
  • Oligoribonucleotides
  • Phosphodiesterase Inhibitors
  • 2',5'-oligoadenylate
  • Exoribonucleases
  • 2'-phosphodiesterase

Associated data

  • GENBANK/AB115695