Modulation of Psoralen DNA Crosslinking Kinetics Associated with a Triplex‐forming Oligonucleotide

Oh, Dennis H.; Suzara, Vincent V.; Krishnan, Rajagopal

doi:10.1111/j.1751-1097.2007.00243.x

Cited by 4 publications

(3 citation statements)

References 21 publications

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“…The rate of photochemically induced monoadduct formation (k 1 ) increases with improved triplex stability (Takasugi et al, 1991;Giovannangeli et al, 1992;Perkins et al, 1999) and is therefore strongly dependent on TFO concentration, whereas k 2 is independent on TFO concentration and may be influenced by the external macromolecular environment (Oh et al, 2008).…”

Section: Crosslinkmentioning

confidence: 99%

Site-Specific DNA Photocleavage and Photomodulation by Oligonucleotide Conjugates

Kolevzon

Yavin

2010

Oligonucleotides

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Triplex-forming oligonucleotides have been explored in the last 3 decades as highly specific gene-modifying agents. Such agents have been showed to either upregulate or shut down gene expression in vitro, an outcome that depends on the specifically designed biological system. One interesting approach is to tether to the oligonucleotide a photoreactive moiety. After hybridization to the DNA target (typically single- or double-stranded DNA), a site-specific photoinduced reaction may take place at a timely manner. Further, as the light source may be focused at a certain area, one has control on the location at which the phototriggered DNA modification takes place. In this regard, the use of tissue-penetrating photons (typically 630-950 nm) would be most relevant for in vivo applications as photoactivation may lead to site-specific DNA modification at a specific tissue/organ. In this review we highlight the advances made in this field and discuss the hurdles that lay ahead for the realization of phototriggered triplex-forming oligonucleotides as a solid therapeutic approach.

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Section: Crosslinkmentioning

confidence: 99%

Site-Specific DNA Photocleavage and Photomodulation by Oligonucleotide Conjugates

Kolevzon

Yavin

2010

Oligonucleotides

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“…Further UVA radiation allows certain monoadducts to react further to form DNA interstrand crosslinks (XL). These photochemical reactions also occur when psoralens are targeted by a TFO, and have been characterized in detail [4,5].…”

Section: Introductionmentioning

confidence: 99%

Real-time observation of DNA repair: 2-aminopurine as a molecular probe

Krishnan

Butcher

2008

SPIE Proceedings

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Triplex forming oligos (TFOs) that target psoralen photoadducts to specific DNA sequences have generated interest as a potential agent in gene therapy. TFOs also offer an opportunity to study the mechanism of DNA repair in detail. In an effort to understand the mechanism of DNA repair at a specific DNA sequence in real-time, we have designed a plasmid containing a psoralen reaction site adjacent to a TFO binding site corresponding to a sequence within the human interstitial collagenase gene. Two 2-aminopurine residues incorporated into the purine-rich strand of the TFO binding site and located within six nucleotides of the psoralen reaction site serve as molecular probes for excision repair events involving the psoralen photoadducts on that DNA strand. In duplex DNA, the 2-aminopurine fluorescence is quenched. However, upon thermal or formamide-induced denaturation of duplex DNA to single stranded DNA, the 2-aminopurine fluorescence increases by eight fold. These results suggest that monitoring 2-aminopurine fluorescence from plasmids damaged by psoralen TFOs may be a method for measuring excision of single-stranded damaged DNA from the plasmid in cells. A fluorescence-based molecular probe to the plasmid may significantly simplify the real-time observation of DNA repair in both populations of cells as well as single cells.

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“…Several studies have shown that such site-specific selectivity is achievable. Notable are extensive studies with psoralen-conjugates, that upon UV irradiation lead to stable cross-links on the target duplex DNA − . Some ODN-conjugates have shown site-specific photoreactivity upon irradiation in the visible region − , and only very few reports have applied dyes that have relevant wavelengths for in vivo applications (i.e.…”

Section: Introductionmentioning

confidence: 99%

DNA Photocleavage by DNA and DNA−LNA Amino Acid−Dye Conjugates

et al. 2010

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DNA photocleavage by triplex forming oligonucleotides (TFO) has potential implications in both biotechnology and medicine. We have synthesized a series of homopurine DNA and DNA/LNA 14-mers to which an amino acid (glycine or l-tryptophan) and a cyanine dye are covalently linked. Two cyanine dyes were examined that include a quinolinium ring linked to a benzothiazolium ring through a monomethine (TO1) or trimethine (TO2) linker. The 14-mer sequence was chosen to target mdm2, a ubiquitin ligase (E3) that regulates p53 by promoting its ubiquitylation and proteosomal degradation. Such inhibition has been previously proposed as a therapeutic approach to target wild-type p53-expressing cancers. To examine whether our TFO conjugates photocleave the mdm2 target, we incubated the various conjugates with the mdm2 plasmid and irradiated the samples with visible light. We show that only the TFO with the complementary sequence and with an intervening l-tryptophan leads to the linearization of the plasmid after a short irradiation time (10 min) exciting the dye (lambda(max)(TO1) = 500 nm and lambda(max)(TO2) = 630 nm) with visible light. Furthermore, the photoreactivity is more pronounced for the LNA/DNA conjugate, an observation that is consistent with improved hybridization to the DNA target. Sequence specificity of the photoreaction is further corroborated on a synthetic 44-mer duplex containing the TFO site. Evidence for a ROS-dependent mechanism is also given and discussed.

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Modulation of Psoralen DNA Crosslinking Kinetics Associated with a Triplex‐forming Oligonucleotide

Cited by 4 publications

References 21 publications

Site-Specific DNA Photocleavage and Photomodulation by Oligonucleotide Conjugates

Site-Specific DNA Photocleavage and Photomodulation by Oligonucleotide Conjugates

Real-time observation of DNA repair: 2-aminopurine as a molecular probe

DNA Photocleavage by DNA and DNA−LNA Amino Acid−Dye Conjugates

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