Exposure of adult Wistar female rats for 7 days to 4 degrees C leads to a marked increase in the weight of the liver and kidney, caused by an increased content of DNA and an increased number of cells in these organs. The weight as well as the DNA content of the cross-striated muscle do not change appreciably. Acclimation of the warmblooded rat to cold stimulates mitosis indirectly in cells capable of division, similarly as it stimulates directly the mitotic activity in mouse and human cells cultured and adapted to cold in vitro.

• MeSH
• aklimatizace * MeSH
• buněčné dělení MeSH
• DNA biosyntéza   MeSH
• fyzikální stimulace MeSH
• fyziologická adaptace MeSH
• játra metabolismus   MeSH
• krysa rodu Rattus MeSH
• ledviny metabolismus   MeSH
• mitóza MeSH
• nízká teplota * MeSH
• svaly metabolismus   MeSH
• velikost orgánu MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• DNA MeSH

Most mitotic homologous recombination (HR) events proceed via a synthesis-dependent strand annealing mechanism to avoid crossing over, which may give rise to chromosomal rearrangements and loss of heterozygosity. The molecular mechanisms controlling HR sub-pathway choice are poorly understood. Here, we show that human RECQ5, a DNA helicase that can disrupt RAD51 nucleoprotein filaments, promotes formation of non-crossover products during DNA double-strand break-induced HR and counteracts the inhibitory effect of RAD51 on RAD52-mediated DNA annealing in vitro and in vivo. Moreover, we demonstrate that RECQ5 deficiency is associated with an increased occupancy of RAD51 at a double-strand break site, and it also causes an elevation of sister chromatid exchanges on inactivation of the Holliday junction dissolution pathway or on induction of a high load of DNA damage in the cell. Collectively, our findings suggest that RECQ5 acts during the post-synaptic phase of synthesis-dependent strand annealing to prevent formation of aberrant RAD51 filaments on the extended invading strand, thus limiting its channeling into potentially hazardous crossover pathway of HR.

• MeSH
• buněčné linie MeSH
• DNA opravný a rekombinační protein Rad52 metabolismus   MeSH
• DNA metabolismus   MeSH
• dvouřetězcové zlomy DNA * MeSH
• helikasy RecQ metabolismus   MeSH
• jednovláknová DNA metabolismus   MeSH
• lidé MeSH
• rekombinační oprava DNA * MeSH
• rekombinasa Rad51 metabolismus   MeSH
• výměna sesterských chromatid MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• DNA opravný a rekombinační protein Rad52 MeSH
• DNA MeSH
• helikasy RecQ MeSH
• jednovláknová DNA MeSH
• RECQL5 protein, human MeSH Prohlížeč
• rekombinasa Rad51 MeSH

The high incidence of chromosomally abnormal human embryos is frequently assumed to be due to a lack of checkpoint controls operating during early embryogenesis. In our study we have analysed when these mechanisms first become functional. Mouse oocytes treated in late metaphase I with either of two different cyclin-dependent kinase inhibitors [butyrolactone 1 (BL1) or 6-dimethylaminopurine (6-DMAP)] form nuclei in the cytoplasm. BL1-treated eggs enter S-phase at 16-18 h post-treatment and, after completion of DNA synthesis, cleave to 2-cell stage embryos. 6-DMAP treatment results in the rapid initiation of DNA synthesis, its completion by 12 h and then arrest in the G2 phase. Thus, two different cell cycle stages can be obtained at the same time point after the initiation of treatment: G1- after BL1 and G2-staged nuclei after 6-DMAP treatment. That this approach greatly facilitates cell cycle studies has been shown by analysing checkpoint function during the first division. Whilst G2-staged eggs enter M phase within 2-3 h when 6-DMAP is washed out, the onset of M phase is delayed after their fusion to G1 (BL1) cells. Here M phase occurs only after the less advanced nucleus completes DNA replication. Our results indicate that checkpoints in mammalian eggs are functional during the first mitotic cycle.

• MeSH
• adenin analogy a deriváty   farmakologie   MeSH
• cyklin-dependentní kinasy antagonisté a inhibitory   MeSH
• DNA biosyntéza   MeSH
• G1 fáze MeSH
• G2 fáze * MeSH
• gama-butyrolakton analogy a deriváty   farmakologie   MeSH
• inhibitory enzymů farmakologie   MeSH
• mitóza * MeSH
• myši inbrední C57BL MeSH
• myši inbrední CBA MeSH
• myši MeSH
• oocyty cytologie   metabolismus   MeSH
• zvířata MeSH
• zygota MeSH
• Check Tag
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, U.S. Gov't, Non-P.H.S. MeSH
• Názvy látek
• adenin MeSH
• butyrolactone I MeSH Prohlížeč
• cyklin-dependentní kinasy MeSH
• DNA MeSH
• gama-butyrolakton MeSH
• inhibitory enzymů MeSH
• N(6),N(6)-dimethyladenine MeSH Prohlížeč

The dynamics of expression of viral proteins gp51 and p24, virus particle production and mitotic activity of a highly productive bovine leukemia virus clone of the fetal lamb kidney (FLK) cell line were studied. The period of the highest protein production (20-44 h after incubation) was established by the indirect immunofluorescence method using specific monoclonal antibodies. It was followed by a complete formation of the cell monolayer and the most intensive period of the mitotic activity determined by the 3H-thymidine labeling method. After the active synthesis of viral protein, the formation of mature viral particles and their shedding in the intercellular spaces was established electron-microscopically and by the syncytia induction test. A similar comparative study was carried out with a BLV producing short-term lymphocyte culture (STLC).

• MeSH
• buněčné linie MeSH
• DNA virů biosyntéza   MeSH
• kočky MeSH
• kultivované buňky MeSH
• mitóza MeSH
• ovce MeSH
• proteiny virového obalu biosyntéza   MeSH
• replikace DNA MeSH
• replikace viru MeSH
• skot MeSH
• virové proteiny biosyntéza   MeSH
• virus bovinní leukemie metabolismus   ultrastruktura   MeSH
• zvířata MeSH
• Check Tag
• kočky MeSH
• skot MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• DNA virů MeSH
• proteiny virového obalu MeSH
• virové proteiny MeSH

An efficient synthetic route for the synthesis of 2H-pyrazolo[4,3-c]pyridines, primarily varying by the substituents at the 2-, 4- and 6-positions, is described here. A Sonogashira-type cross-coupling reaction was employed to yield 3-alkynyl-1H-pyrazole-4-carbaldehydes, ethanones and propanones from the corresponding 1H-pyrazol-3-yl trifluoromethanesulfonates. Subsequent treatment of the coupling products with dry ammonia afforded a versatile library of 2H-pyrazolo[4,3-c]pyridines, which were then evaluated for their cytotoxicity against K562 and MCF-7 cancer cell lines. The most potent of these compounds displayed low micromolar GI50 values in both cell lines. Active compounds induced dose-dependent cell-cycle arrest in mitosis, as shown by flow cytometric analysis of DNA content and phosphorylation of histone H3 at serine-10. Moreover, biochemical assays revealed increased activities of caspases-3/7 in treated cells, specific fragmentation of PARP-1, and phosphorylation of Bcl-2, collectively confirming apoptosis as the mechanism of cell death.

• Klíčová slova
• Apoptosis, G2/M cell cycle arrest, Pyrazole, Structure-activity relationships,
• MeSH
• antimitotika chemická syntéza   chemie   farmakologie   MeSH
• buněčná smrt účinky léků   MeSH
• buňky K562 MeSH
• kontrolní body buněčného cyklu účinky léků   MeSH
• lidé MeSH
• MFC-7 buňky MeSH
• mitóza účinky léků   MeSH
• molekulární struktura MeSH
• proliferace buněk účinky léků   MeSH
• protinádorové látky chemická syntéza   chemie   farmakologie   MeSH
• pyridiny chemie   farmakologie   MeSH
• screeningové testy protinádorových léčiv MeSH
• vztah mezi dávkou a účinkem léčiva MeSH
• vztahy mezi strukturou a aktivitou MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• antimitotika MeSH
• protinádorové látky MeSH
• pyridiny MeSH

Mitotic activity, as indicated by DNA synthesis, was studied by autoradiographic analysis along the proximodistal axis of regenerating limbs in the early and later larval stages 53 and 57 of Xenopus laevis. Wound-healing, dedifferentiation, blastema formation and growth phases were studied. Most of the various stump tissues, as well as the cell mass of the regeneration blastema, were involved. The study showed an increase in DNA synthesis in the stump tissues during their dedifferentiation as well as during blastema formation. The increase was confined mainly to the distal portion (close to the amputation level), so that a proximodistal gradient was discernible. This could be regarded as valid evidence of contribution of the severed stump tissues to the blastema cells. The mesenchymal blastema cells formed after amputation at stage 53 displayed higher mitotic activity than the fibrocytoid blastema cells formed at stage 57. Although the latter were more differentiated than the former, they still showed DNA replication and mitotic division.

• MeSH
• autoradiografie MeSH
• mitóza fyziologie   MeSH
• pahýl po amputaci patofyziologie   MeSH
• regenerace fyziologie   MeSH
• tarzus u zvířat MeSH
• Xenopus laevis fyziologie   MeSH
• zadní končetina MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH

Defects in DNA repair frequently lead to neurodevelopmental and neurodegenerative diseases, underscoring the particular importance of DNA repair in long-lived post-mitotic neurons1,2. The cellular genome is subjected to a constant barrage of endogenous DNA damage, but surprisingly little is known about the identity of the lesion(s) that accumulate in neurons and whether they accrue throughout the genome or at specific loci. Here we show that post-mitotic neurons accumulate unexpectedly high levels of DNA single-strand breaks (SSBs) at specific sites within the genome. Genome-wide mapping reveals that SSBs are located within enhancers at or near CpG dinucleotides and sites of DNA demethylation. These SSBs are repaired by PARP1 and XRCC1-dependent mechanisms. Notably, deficiencies in XRCC1-dependent short-patch repair increase DNA repair synthesis at neuronal enhancers, whereas defects in long-patch repair reduce synthesis. The high levels of SSB repair in neuronal enhancers are therefore likely to be sustained by both short-patch and long-patch processes. These data provide the first evidence of site- and cell-type-specific SSB repair, revealing unexpected levels of localized and continuous DNA breakage in neurons. In addition, they suggest an explanation for the neurodegenerative phenotypes that occur in patients with defective SSB repair.

• MeSH
• 5-methylcytosin metabolismus   MeSH
• buněčné linie MeSH
• DNA biosyntéza   MeSH
• jednořetězcové zlomy DNA * MeSH
• lidé MeSH
• metylace MeSH
• neurony metabolismus   MeSH
• oprava DNA * MeSH
• poly(ADP-ribosa)polymerasy metabolismus   MeSH
• replikace DNA MeSH
• sekvenční analýza DNA MeSH
• zesilovače transkripce genetika   MeSH
• Check Tag
• lidé MeSH
• mužské pohlaví MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Research Support, N.I.H., Intramural MeSH
• Názvy látek
• 5-methylcytosin MeSH
• DNA MeSH
• poly(ADP-ribosa)polymerasy MeSH

The MUS81-EME1 endonuclease cleaves late replication intermediates at common fragile sites (CFSs) during early mitosis to trigger DNA-repair synthesis that ensures faithful chromosome segregation. Here, we show that these DNA transactions are promoted by RECQ5 DNA helicase in a manner dependent on its Ser727 phosphorylation by CDK1. Upon replication stress, RECQ5 associates with CFSs in early mitosis through its physical interaction with MUS81 and promotes MUS81-dependent mitotic DNA synthesis. RECQ5 depletion or mutational inactivation of its ATP-binding site, RAD51-interacting domain, or phosphorylation site causes excessive binding of RAD51 to CFS loci and impairs CFS expression. This leads to defective chromosome segregation and accumulation of CFS-associated DNA damage in G1 cells. Biochemically, RECQ5 alleviates the inhibitory effect of RAD51 on 3'-flap DNA cleavage by MUS81-EME1 through its RAD51 filament disruption activity. These data suggest that RECQ5 removes RAD51 filaments stabilizing stalled replication forks at CFSs and hence facilitates CFS cleavage by MUS81-EME1.

• Klíčová slova
• MUS81, RAD51 filament, RECQ5, common fragile sites, genomic instability, mitotic DNA synthesis, replication stress,
• MeSH
• časové faktory MeSH
• chromozomální nestabilita MeSH
• cyklin-dependentní kinasy metabolismus   MeSH
• DNA vazebné proteiny genetika   metabolismus   MeSH
• DNA biosyntéza   genetika   MeSH
• endodeoxyribonukleasy metabolismus   MeSH
• endonukleasy genetika   metabolismus   MeSH
• fosforylace MeSH
• fragilní místa na chromozomu * MeSH
• HEK293 buňky MeSH
• HeLa buňky MeSH
• helikasy RecQ genetika   metabolismus   MeSH
• lidé MeSH
• mitóza * MeSH
• oprava DNA * MeSH
• poškození DNA MeSH
• proteinkinasa CDC2 MeSH
• rekombinasa Rad51 metabolismus   MeSH
• replikační počátek * MeSH
• RNA interference MeSH
• segregace chromozomů MeSH
• transfekce MeSH
• vazba proteinů MeSH
• vazebná místa MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• CDK1 protein, human MeSH Prohlížeč
• cyklin-dependentní kinasy MeSH
• DNA vazebné proteiny MeSH
• DNA MeSH
• Eme1 protein, human MeSH Prohlížeč
• endodeoxyribonukleasy MeSH
• endonukleasy MeSH
• helikasy RecQ MeSH
• MUS81 protein, human MeSH Prohlížeč
• proteinkinasa CDC2 MeSH
• RAD51 protein, human MeSH Prohlížeč
• RECQL5 protein, human MeSH Prohlížeč
• rekombinasa Rad51 MeSH

Hydrocortisone sodium succinate (65 mg/kg body weight), Zn-ACTH (40 U/kg) and the intraperitoneal injection of Celite (200 mg/kg) decrease the incorporation of 14C-thymidine into the DNA of regenerating rat liver by about 60%. This decrease is not followed by a corresponding inhibition of cell division. The agents applied at the end of G1 phase or in the S phase of the cell cycle probably change thymidine metabolism and the observed decrease of thymidine incorporation does not represent true inhibition of DNA synthesis. The experiment with regenerating liver slices has shown that this disproportion is partly caused by decreased 14C-thymidine transport into the cells.

• MeSH
• anestezie MeSH
• DNA metabolismus   MeSH
• hydrokortison farmakologie   MeSH
• injekce intraperitoneální MeSH
• játra metabolismus   MeSH
• krysa rodu Rattus MeSH
• mitóza účinky léků   MeSH
• regenerace jater účinky léků   MeSH
• thymidin metabolismus   MeSH
• vysoká teplota MeSH
• zvířata MeSH
• Check Tag
• krysa rodu Rattus MeSH
• mužské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• Názvy látek
• DNA MeSH
• hydrokortison MeSH
• thymidin MeSH

This study is a thorough examination of the effects of the DNA polymerase inhibitor aphidicolin on the nuclear cycle and cell cycle progression characteristics, as well as their reversibility, in Giardia intestinalis. Giardia trophozoites are arrested in the G1/S-junction after aphidicolin treatment according to their DNA content. However, cell growth continues and trophozoites arrested with aphidicolin resemble cells in the G2 phase and trophozoites in ageing cultures. Extensive treatment with aphidicolin causes side effects and we detected positive signals for phosphorylated histone H2A, which, in mammalian cells, is involved in a signalling pathway triggered as a reaction to double stranded DNA breaks. These results suggest that aphidicolin causes dissociation of the nuclear and cytoplasmic cycles, a phenomenon that has also been described for other inhibitors in mammalian cell lines. Thus, if aphidicolin is used for synchronization of Giardia trophozoites, this fact must be accounted for, and treatment with aphidicolin must be minimal.

• MeSH
• afidikolin farmakologie   MeSH
• bromodeoxyuridin metabolismus   MeSH
• buněčný cyklus účinky léků   MeSH
• časové faktory MeSH
• cyklin B analýza   MeSH
• fluorescenční protilátková technika MeSH
• fosforylace účinky léků   MeSH
• Giardia lamblia cytologie   účinky léků   genetika   MeSH
• histony metabolismus   MeSH
• inhibitory enzymů farmakologie   MeSH
• inhibitory syntézy nukleových kyselin MeSH
• mitotický index MeSH
• poškození DNA účinky léků   MeSH
• protozoální DNA biosyntéza   účinky léků   MeSH
• průtoková cytometrie MeSH
• replikace DNA účinky léků   MeSH
• trofozoiti cytologie   účinky léků   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH
• Názvy látek
• afidikolin MeSH
• bromodeoxyuridin MeSH
• cyklin B MeSH
• histony MeSH
• inhibitory enzymů MeSH
• inhibitory syntézy nukleových kyselin MeSH
• protozoální DNA MeSH