Mishra M, Bennett JR, Chaudhuri G. Increased efficacy of antileishmanial
antisense phosphorothioate oligonucleotides in Leishmania amazonensis overexpressing ribonuclease H.
Biochem Pharmacol 2001;
61:467-76. [PMID:
11226381 PMCID:
PMC3088082 DOI:
10.1016/s0006-2952(00)00568-2]
[Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Ribonuclease H (RNase H), an enzyme that cleaves an RNA sequence base-paired with a complementary DNA sequence, is proposed to be the mediator of antisense phosphorothioate oligonucleotide (S-oligo) lethality in a cell. To understand the role of RNase H in the killing of the parasitic protozoan Leishmania by antisense S-oligos, we expressed an episomal copy of the Trypanosoma brucei RNase H1 gene inside L. amazonensis promastigotes and amastigotes that constitutively express firefly luciferase. Our hypothesis was that S-oligo-directed degradation of target mRNA is facilitated in a cell that has higher RNase H activity. Increased inhibition of luciferase mRNA expression by anti-luciferase S-oligo and by anti-miniexon S-oligo in these stably transfected promastigotes overexpressing RNase H1 was correlated to the higher activity of RNase H in these cells. The efficiency of killing of the RNase H overexpressing amastigotes inside L. amazonensis-infected macrophages by anti-miniexon S-oligo was higher than in the control cells. Thus, RNase H appears to play an important role in the antisense S-oligo-mediated killing of Leishmania. Chemical modification of S-oligos that stimulate RNase H and/or co-treatment of cells with an activator of RNase H may be useful for developing an antisense approach against leishmaniasis. The transgenic Leishmania cells overexpressing RNase H should be a good model system for the antisense-mediated gene expression ablation studies in these parasites.
Collapse