Resistance of human hepatitis delta virus RNAs to dicer activity.
The endonuclease dicer cleaves RNAs that are 100% double stranded and certain RNAs with extensive but <100% pairing to release approximately 21-nucleotide (nt) fragments. Circular 1,679-nt genomic and antigenomic RNAs of human hepatitis delta virus (HDV) can fold into a rod-like structure with 74% pairing. However, during HDV replication in hepatocytes of human, woodchuck, and mouse origin, no approximately 21-nt RNAs were detected. Likewise, in vitro, purified recombinant dicer gave <0.2% cleavage of unit-length HDV RNAs. Similarly, rod-like RNAs of potato spindle tuber viroid (PSTVd) and avocado sunblotch viroid (ASBVd) were only 0.5% cleaved. Furthermore, when a 66-nt hairpin RNA with 79% pairing, the putative precursor to miR-122, which is an abundant liver micro-RNA, replaced one end of HDV genomic RNA, it was poorly cleaved, both in vivo and in vitro. In contrast, this 66-nt hairpin, in the absence of appended HDV sequences, was >80% cleaved in vitro. Other 66-nt hairpins derived from one end of genomic HDV, PSTVd, or ASBVd RNAs were also cleaved. Apparently, for unit-length RNAs of HDV, PSTVd, and ASBVd, it is the extended structure with <100% base pairing that confers significant resistance to dicer action.
Fox Chase Cancer Center, Philadelphia, Pennsylvania 19111-2497, USA.
Jinhong
J
Chang
Patrick
P
Provost
John M
JM
Taylor
D016679:Genome, Viral; D003698:Hepatitis Delta Virus / Q000235:genetics*; D035923:Hepatitis delta Antigens / Q000502:physiology; D034741:RNA, Small Interfering / Q000032:analysis; D012367:RNA, Viral / Q000737:chemistry / Q000378:metabolism*; D011994:Recombinant Proteins / Q000494:pharmacology; D043244:Ribonuclease III / Q000494:pharmacology*; D014779:Virus Replication
D035923:Hepatitis delta Antigens; D034741:RNA, Small Interfering; D012367:RNA, Viral; D011994:Recombinant Proteins; D043244:Ribonuclease III