Developmental processes are closely connected to certain states of epigenetic information which, among others, rely on methylation of chromatin. S-adenosylmethionine (SAM) and S-adenosylhomocysteine (SAH) are key cofactors of enzymes catalyzing DNA and histone methylation. To study the consequences of altered SAH/SAM levels on plant development we applied 9-(S)-(2,3-dihydroxypropyl)-adenine (DHPA), an inhibitor of SAH-hydrolase, on tobacco seeds during a short phase of germination period (6 days). The transient drug treatment induced: (1) dosage-dependent global DNA hypomethylation mitotically transmitted to adult plants; (2) pleiotropic developmental defects including decreased apical dominance, altered leaf and flower symmetry, flower whorl malformations and reduced fertility; (3) dramatic upregulation of floral organ identity genes NTDEF, NTGLO and NAG1 in leaves. We conclude that temporal SAH-hydrolase inhibition deregulated floral genes expression probably via chromatin methylation changes. The data further show that plants might be particularly sensitive to accurate setting of SAH/SAM levels during critical developmental periods.
- MeSH
- adenin analogy a deriváty toxicita MeSH
- adenosylhomocysteinasa antagonisté a inhibitory metabolismus MeSH
- DNA primery genetika MeSH
- epigeneze genetická účinky léků fyziologie MeSH
- klíčení účinky léků fyziologie MeSH
- komplementární DNA genetika MeSH
- květy anatomie a histologie fyziologie MeSH
- metylace DNA MeSH
- neparametrická statistika MeSH
- pyl fyziologie MeSH
- regulace genové exprese u rostlin účinky léků genetika fyziologie MeSH
- rostlinné proteiny metabolismus MeSH
- Southernův blotting MeSH
- tabák enzymologie fyziologie MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
9-(S)-[3-Hydroxy-2-(phosphonomethoxy)propyl]-2,6-diaminopurine (HPMPDAP) and its cyclic form were selected for further evaluation as potential drug candidates against poxvirus infections. To increase bioavailability of these compounds, synthesis of their structurally diverse ester prodrugs was carried out: alkoxyalkyl (hexadecyloxypropyl, octadecyloxyethyl, hexadecyloxyethyl), pivaloyloxymethyl (POM), 2,2,2-trifluoroethyl, butylsalicylyl, and prodrugs based on peptidomimetics. Most HPMPDAP prodrugs were synthesized in the form of monoesters as well as the corresponding cyclic phosphonate esters. The activity was evaluated not only against vaccinia virus but also against different herpes viruses. The most potent and active prodrugs against vaccinia virus were the alkoxyalkyl ester derivatives of HPMPDAP, with 50% effective concentrations 400-600-fold lower than those of the parent compound. Prodrugs based on peptidomimetics, the 2,2,2-trifluoroethyl, the POM, and the butylsalicylyl derivatives, were able to inhibit vaccinia virus replication at 50% effective concentrations that were equivalent or ∼10-fold lower than those observed for the parent compounds.
- MeSH
- adenin analogy a deriváty chemická syntéza chemie farmakologie MeSH
- antivirové látky chemická syntéza chemie farmakologie MeSH
- estery MeSH
- Herpesviridae účinky léků MeSH
- kultivované buňky MeSH
- lidé MeSH
- organofosforové sloučeniny chemická syntéza chemie farmakologie MeSH
- Poxviridae účinky léků MeSH
- prekurzory léčiv chemická syntéza chemie farmakologie MeSH
- proliferace buněk účinky léků MeSH
- RNA-viry účinky léků MeSH
- stereoizomerie MeSH
- virologie metody MeSH
- vztahy mezi strukturou a aktivitou MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
- Research Support, N.I.H., Extramural MeSH
We have previously shown that PMEG diphosphate (PMEGpp) and PMEDAP diphosphate (PMEDAPpp) inhibit the enzymatic activity of human telomerase in a cell-free assay. Here, we investigated the ability of PMEG and PMEDAP to induce telomere shortening and telomerase inhibition at both transcriptional and activity level in T-lymphoblastic leukemia cells CCRF-CEM and MOLT-4. At defined time points (3days and 9weeks), the telomerase activity and relative levels of hTERT and c-myc mRNA were determined using real-time RT-PCR. Telomere length was measured by the flow-FISH method. Both PMEDAP and PMEG induced telomere shortening in CCRF-CEM cells after 9weeks of exposure by 50% and 20%, respectively, without major impairment of telomerase activity. The effect of the tested compounds on telomere length in MOLT-4 cells was the opposite, with telomere elongation by 50% and 40% after 9-week treatment with PMEDAP and PMEG, respectively. At this time point, telomerase activity in MOLT-4 cells appeared to be slightly higher than that of CCRF-CEM cells, nevertheless no correlation between telomerase activity and telomere length was found. Both compounds down-regulated the expression of hTERT and c-myc mRNA in CCRF-CEM and MOLT-4 cells at 72h in a concentration-dependent manner while prolonged exposure to PMEG or PMEDAP for 9weeks had weaker effects. In conclusion, PMEDAP and PMEG are able to modulate telomere length in leukemic cells and this effect is cell-type specific. It is neither due to direct telomerase inhibition nor impairment of hTERT expression and it is likely to be telomerase-independent.
- MeSH
- adenin analogy a deriváty farmakologie MeSH
- antitumorózní látky farmakologie MeSH
- buněčné kultury MeSH
- časové faktory MeSH
- elektroforéza v polyakrylamidovém gelu MeSH
- guanin analogy a deriváty farmakologie MeSH
- hybridizace in situ fluorescenční MeSH
- lidé MeSH
- nádorové buněčné linie MeSH
- organofosforové sloučeniny farmakologie MeSH
- polymerázová řetězová reakce s reverzní transkripcí MeSH
- protoonkogenní proteiny c-myc biosyntéza MeSH
- RNA metabolismus MeSH
- telomerasa antagonisté a inhibitory biosyntéza MeSH
- telomery účinky léků MeSH
- vztah mezi dávkou a účinkem léčiva MeSH
- Check Tag
- lidé MeSH
- Publikační typ
- časopisecké články MeSH
- práce podpořená grantem MeSH
Non-covalent interactions play an important role in chemistry, physics and especially in biodisciplines. They determine the structure of biomacromolecules such as DNA and proteins and are responsible for the molecular recognition process. Theoretical evaluation of interaction energies is difficult; however, perturbation as well as variation (supermolecular) methods are briefly described. Accurate interaction energies can be obtained by complete basis set limit calculations providing a large portion of correlation energy is covered (e.g. by performing CCSD(T) calculations). The role of H-bonding and stacking interactions in the stabilisation of DNA, oligopeptides and proteins is described, and the importance of London dispersion energy is shown.
The inhibitory and/or substrate activity of 1-[(S)-3-hydroxy-2-(phosphonomethoxy)propyl]cytosine [(S)-HPMPC, cidofovir, Vistide™] diphosphate towards eukaryotic DNA polymerases α, δ and ε* was examined. Cidofovir diphosphate is a weak competitive inhibitor of the above enzymes, approximately 3 to 7 times weaker than its adenine analogue (S)-HPMPApp. The enzymes also catalyze incorporation of (S)-HPMPC into DNA; after insertion of one (S)-HPMPC residue into DNA, another dNMP residue may incorporate. DNA polymerase δ and ε* can successively accommodate in the growing chain two (S)-HPMPC residues at the maximum, whereas pol α up to three residues.
