» Articles » PMID: 9115364

Investigation of the Formation and Intracellular Stability of Purine.(purine/pyrimidine) Triplexes

Overview
Specialty Biochemistry
Date 1997 May 15
PMID 9115364
Citations 1
Authors
Affiliations
Soon will be listed here.
Abstract

In a previous work we showed that a short triple helix-forming oligonucleotide (TFO) targeted to the murine c-pim-1 proto-oncogene promoter gives a very stable triple helix under physiological conditions in vitro . Moreover, this triplex was stable inside cells when preformed in vitro . However, we failed to detect triplex formation for this sequence inside cells in DMS footprinting studies. In the present work, in order to determine whether our previous in vivo results are limited to this particular short triplex or can be generalized to other purine.(purine/pyrimidine) triplexes, we have tested three other DNA targets already described in the literature. All these purine.(purine/pyrimidine) triplexes are specific and stable at high temperature in vitro . In vivo studies have shown that the preformed triplexes are stable inside cells for at least 3 days. This clearly demonstrates that intracellular conditions are favourable for the existence of purine. (purine/pyrimidine) triplexes. The triplexes can also be formed in nuclei. However, for all the sequences tested, we were unable to detect any triple helix formation in vivo in intact cells by DMS footprinting. Our results show that neither (i) chromatinization of the DNA target, (ii) intracellular K+concentration nor (iii) cytoplasmic versus nuclear separation of the TFO and DNA target are responsible for the intracellular arrest of triplex formation. We suggest the existence of a cellular mechanism, based on a compartmentalization of TFOs and/or TFO trapping, which separates oligonucleotides from the DNA target. Further work is needed to find oligonucleotide derivatives and means for their delivery to overcome the problem of triplex formation inside cells.

Citing Articles

Detection of competing DNA structures by thermal gradient gel electrophoresis: from self-association to triple helix formation by (G,A)-containing oligonucleotides.

Arimondo P, Garestier T, Helene C, Sun J Nucleic Acids Res. 2001; 29(4):E15.

PMID: 11160935 PMC: 29622. DOI: 10.1093/nar/29.4.e15.

References
1.
Cereghini S, Yaniv M . Assembly of transfected DNA into chromatin: structural changes in the origin-promoter-enhancer region upon replication. EMBO J. 1984; 3(6):1243-53. PMC: 557505. DOI: 10.1002/j.1460-2075.1984.tb01959.x. View

2.
Fisher T, Terhorst T, Cao X, Wagner R . Intracellular disposition and metabolism of fluorescently-labeled unmodified and modified oligonucleotides microinjected into mammalian cells. Nucleic Acids Res. 1993; 21(16):3857-65. PMC: 309908. DOI: 10.1093/nar/21.16.3857. View

3.
Cooney M, Czernuszewicz G, POSTEL E, Flint S, Hogan M . Site-specific oligonucleotide binding represses transcription of the human c-myc gene in vitro. Science. 1988; 241(4864):456-9. DOI: 10.1126/science.3293213. View

4.
Bazile D, Mir L, Paoletti C . Voltage-dependent introduction of a d[alpha]octothymidylate into electropermeabilized cells. Biochem Biophys Res Commun. 1989; 159(2):633-9. DOI: 10.1016/0006-291x(89)90041-7. View

5.
Rocancourt D, Bonnerot C, Jouin H, Emerman M, Nicolas J . Activation of a beta-galactosidase recombinant provirus: application to titration of human immunodeficiency virus (HIV) and HIV-infected cells. J Virol. 1990; 64(6):2660-8. PMC: 249444. DOI: 10.1128/JVI.64.6.2660-2668.1990. View