9-Aminoellipticine-Derivatized α- and β-Oligodeoxyribonucleotides Targeted to the Cap of β-Globin mRNA: Hybridization to Natural and Engineered mRNA, Inhibition of Translation, and Improved Effect of Tandem Chains

Abstract

We studied the duplex stability and the antimessenger activity of 9-aminoellipticine-5'-functionalized alpha- and beta-anomeric DNA sequences complementary to the first 14 nucleotides of the rabbit beta-globin mRNA. The duplex formed by the beta-conjugate with the natural mRNA target possessed a marginally better stability to that of the duplex formed by the unfunctionalized compound, as measured by the thermal elution. The alpha-conjugate did not anneal to native mRNA, possibly due to the interference of the 9-aminoellipticine with the cap structure and, unlike the beta-adduct, was practically inactive as inhibitor of translation in a cell-free system. However, it did hybridize to an RNA construction containing the beta-globin mRNA plus an additional 50 bases in 5'. Surprisingly, translation from this construction was inhibited by the alpha-species in spite of the nonvicinity of the target to the cap. Both alpha and beta conjugates hybridized to a DNA 14-mer of the same sequence as that targeted onto the mRNA. Thermal denaturation and fluorescence spectroscopy showed that the drug brought no considerable stabilization to the duplex, the linker presumably being unfavorable to intercalation. An increased stability of the complex and a higher inhibitory effect on cell-free beta-globin translation were obtained with two contiguous beta-oligomers of which one was functionalized.

Photochemically and chemically activatable antisense oligonucleotides: comparison of their reactivities towards DNA and RNA targets

“…Maher and Dolnick have shown that the efficiency of translation arrest could be increased if two oligonucleotides were targeted to tandem binding sites (27). Contiguously bound oligonucleotides have also been shown to increase the stability of Oligo/RNA duplexes and to enhance translation inhibition by ellipticine-derivatized oligonucleotides (28). Reynolds et al obtained efficient photoadducts with AMTderivatized l9mer methylphosphonate oligonucleotides targeted to a 440 base-long bcr/abl RNA target, provided they used two additional tandem oligonucleotides to induce the reaction (29).…”

Genetic strategies for the treatment of sickle cell anaemia

“…These oligonucleotides bind to DNA in the major groove in a sequence‐specific manner to form triple helices. TFOs can also be conjugated to a mutagen, such as psoralen, to introduce mutations at the target site (Duval‐Valentin et al , 1992; Porumb et al , 1992, 1996; Xu et al , 2000; Kalish & Glazer, 2005; Shahid et al , 2006). Targeted activation of HBG gene expression has been obtained through psoralen‐TFO‐mediated mutagenesis to the −280 region of the OCT‐1 promoter in murine erythroleukaemia (MEL) cells (Xu et al , 2000).…”