Cytochrome c oxidase (COX), the terminal enzyme of mitochondrial electron transport chain, couples electron transport to oxygen with generation of proton gradient indispensable for the production of vast majority of ATP molecules in mammalian cells. The review summarizes current knowledge of COX structure and function of nuclear-encoded COX subunits, which may modulate enzyme activity according to various conditions. Moreover, some nuclear-encoded subunits posess tissue-specific and development-specific isoforms, possibly enabling fine-tuning of COX function in individual tissues. The importance of nuclear-encoded subunits is emphasized by recently discovered pathogenic mutations in patients with severe mitopathies. In addition, proteins substoichiometrically associated with COX were found to contribute to COX activity regulation and stabilization of the respiratory supercomplexes. Based on the summarized data, a model of three levels of quaternary COX structure is postulated. Individual structural levels correspond to subunits of the i) catalytic center, ii) nuclear-encoded stoichiometric subunits and iii) associated proteins, which may constitute several forms of COX with varying composition and differentially regulated function.

• MeSH
• buněčné jádro enzymologie   genetika   MeSH
• genom MeSH
• lidé MeSH
• mitochondriální nemoci enzymologie   patologie   MeSH
• mitochondrie enzymologie   genetika   MeSH
• orgánová specificita MeSH
• podjednotky proteinů MeSH
• respirační komplex IV genetika   metabolismus   MeSH
• signální transdukce MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• přehledy MeSH

Phosphoinositides (PIs) are phosphorylated derivatives of phosphatidylinositol. They act as signaling molecules linked to essential cellular mechanisms in eukaryotic cells, such as cytoskeleton organization, mitosis, polarity, migration or invasion. PIs are phosphorylated and dephosphorylated by a large number of PI kinases and PI phosphatases acting at the 5-, 4- and 3- position of the inositol ring. PI 5-phosphatases i.e. OCRL, INPP5B, SHIP1/2, Synaptojanin 1/2, INPP5E, INPP5J, SKIP (INPP5K) are enzymes that dephosphorylate the 5-phosphate position of PIs. Several human genetic diseases such as the Lowe syndrome, some congenital muscular dystrophy and opsismodysplasia are due to mutations in PI phosphatases, resulting in loss-of-function. The PI phosphatases are also up or down regulated in several human cancers such as glioblastoma or breast cancer. Their cellular localization, that is dynamic and varies in response to stimuli, is an important issue to understand function. This is the case for two members of the PI 5-phosphatase SKIP and SHIP2. Both enzymes are in ruffles, plasma membranes, the endoplasmic reticulum, a situation that is unique for SKIP, and the nucleus. Following localization, PI 5-phosphatases act on specific cellular pools of PIs, which in turn interact with target proteins. Nuclear PIs have emerged as regulators of genome functions in different area of cell signaling. They often localize to nuclear speckles, as do several PI metabolizing kinases and phosphatases. We asked whether SKIP and SHIP2 could have an impact on nuclear PI(4,5)P2. In two glioblastoma cell models, lowering SKIP expression had an impact on nuclear PI(4,5)P2. In a model of SHIP2 deletion in MCF-7 cells, no change in nuclear PI(4,5)P2 was observed. Finally, we present evidence of an anti-tumoral role of SKIP in vivo, in xenografts using as model U87shSKIP cells.

• MeSH
• buněčné jádro enzymologie   genetika   MeSH
• endoplazmatické retikulum enzymologie   genetika   patologie   MeSH
• fosfatasy genetika   metabolismus   MeSH
• fosfatidylinositol-3,4,5-trisfosfát-5-fosfatasy genetika   metabolismus   MeSH
• glioblastom enzymologie   genetika   patologie   MeSH
• lidé MeSH
• MFC-7 buňky MeSH
• myši inbrední NOD MeSH
• myši SCID MeSH
• myši MeSH
• nádorové proteiny genetika   metabolismus   MeSH
• nádory prsu enzymologie   genetika   patologie   MeSH
• zvířata MeSH
• Check Tag
• lidé MeSH
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Inosine-5'-monophosphate dehydrogenase catalyzes the critical step in the de novo synthesis of guanosine nucleotides: the oxidation of inosine monophosphate to xanthosine monophosphate. This reaction can be inhibited by specific inhibitors, such as ribavirin or mycophenolic acid, which are widely used in clinical treatment when required to inhibit the proliferation of viruses or cells. However, it was recently found that such an inhibition affects the cells, leading to a redistribution of IMPDH2 and the appearance of IMPDH2 inclusions in the cytoplasm. According to their shape, these inclusions have been termed "Rods and Rings" (R&R). In this work, we focused on the subcellular localization of IMPDH2 protein and the ultrastructure of R&R inclusions. Using microscopy and western blot analysis, we show the presence of nuclear IMPDH2 in human cells. We also show that the nuclear pool has an ability to form Rod structures after inhibition by ribavirin. Concerning the ultrastructure, we observed that R&R inclusions in cellulo correspond to the accumulation of fibrous material that is not surrounded by a biological membrane. The individual fibers are composed of regularly repeating subunits with a length of approximately 11 nm. Together, our findings describe the localization of IMPDH2 inside the nucleus of human cells as well as the ultrastructure of R&R inclusions.

• MeSH
• aktivní transport - buněčné jádro účinky léků   MeSH
• buněčné jádro enzymologie   metabolismus   ultrastruktura   MeSH
• cytoplazma enzymologie   ultrastruktura   MeSH
• HeLa buňky MeSH
• IMP-dehydrogenasa antagonisté a inhibitory   chemie   metabolismus   ultrastruktura   MeSH
• inhibitory enzymů farmakologie   MeSH
• lidé MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Although telomerase (EC 2.7.7.49) is important for genome stability and totipotency of plant cells, the principles of its regulation are not well understood. Therefore, we studied subcellular localization and function of the full-length and truncated variants of the catalytic subunit of Arabidopsis thaliana telomerase, AtTERT, in planta. Our results show that multiple sites in AtTERT may serve as nuclear localization signals, as all the studied individual domains of the AtTERT were targeted to the nucleus and/or the nucleolus. Although the introduced genomic or cDNA AtTERT transgenes display expression at transcript and protein levels, they are not able to fully complement the lack of telomerase functions in tert -/- mutants. The failure to reconstitute telomerase function in planta suggests a more complex telomerase regulation in plant cells than would be expected based on results of similar experiments in mammalian model systems.

• MeSH
• Arabidopsis enzymologie   genetika   MeSH
• buněčné jadérko enzymologie   genetika   MeSH
• buněčné jádro enzymologie   genetika   MeSH
• geneticky modifikované rostliny MeSH
• jaderné lokalizační signály genetika   MeSH
• katalytická doména genetika   MeSH
• listy rostlin genetika   MeSH
• proteiny huseníčku genetika   metabolismus   MeSH
• proteosyntéza MeSH
• regulace genové exprese u rostlin MeSH
• sestřih RNA MeSH
• tabák genetika   MeSH
• telomerasa chemie   genetika   metabolismus   MeSH
• terciární struktura proteinů MeSH
• vztahy mezi strukturou a aktivitou MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

O-Acetylserine(thiol)lyases (OAS-TLs) play a pivotal role in a sulfur assimilation pathway incorporating sulfide into amino acids in microorganisms and plants, however, these enzymes have not been found in the animal kingdom. Interestingly, the genome of the roundworm Caenorhabditis elegans contains three expressed genes predicted to encode OAS-TL orthologs (cysl-1-cysl-3), and a related pseudogene (cysl-4); these genes play different roles in resistance to hypoxia, hydrogen sulfide and cyanide. To get an insight into the underlying molecular mechanisms we purified the three recombinant worm OAS-TL proteins, and we determined their enzymatic activities, substrate binding affinities, quaternary structures and the conformations of their active site shapes. We show that the nematode OAS-TL orthologs can bind O-acetylserine and catalyze the canonical reaction although this ligand may more likely serve as a competitive inhibitor to natural substrates instead of being a substrate for sulfur assimilation. In addition, we propose that S-sulfocysteine may be a novel endogenous substrate for these proteins. However, we observed that the three OAS-TL proteins are conformationally different and exhibit distinct substrate specificity. Based on the available evidences we propose the following model: CYSL-1 interacts with EGL-9 and activates HIF-1 that upregulates expression of genes detoxifying sulfide and cyanide, the CYSL-2 acts as a cyanoalanine synthase in the cyanide detoxification pathway and simultaneously produces hydrogen sulfide, while the role of CYSL-3 remains unclear although it exhibits sulfhydrylase activity in vitro. All these data indicate that C. elegans OAS-TL paralogs have distinct cellular functions and may play different roles in maintaining hydrogen sulfide homeostasis.

• MeSH
• buněčné jádro chemie   enzymologie   genetika   MeSH
• Caenorhabditis elegans enzymologie   genetika   MeSH
• cysteinsynthasa chemie   genetika   metabolismus   MeSH
• homeostáza fyziologie   MeSH
• katalytická doména MeSH
• kyanidy metabolismus   MeSH
• proteiny Caenorhabditis elegans chemie   genetika   metabolismus   MeSH
• serin analogy a deriváty   chemie   genetika   metabolismus   MeSH
• substrátová specifita MeSH
• sulfan chemie   metabolismus   MeSH
• zvířata MeSH
• Check Tag
• zvířata MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Apoptosis is a natural form of cell death involved in many physiological changes in the cell. Defects in the process of apoptosis can lead to serious diseases. During some apoptotic pathways, proteins apoptosis-inducing factor (AIF) and endonuclease G (EndoG) are released from the mitochondria and they translocate into the cell nuclei, where they probably participate in chromatin degradation together with other nuclear proteins. Exact mechanism of EndoG activity in cell nucleus is still unknown. Some interacting partners like flap endonuclease 1, DNase I, and exonuclease III were already suggested, but also other interacting partners were proposed. We conducted a living-cell confocal fluorescence microscopy followed by an image analysis of fluorescence resonance energy transfer to analyze the possibility of protein interactions of EndoG with histone H2B and human DNA topoisomerase II alpha (TOPO2a). Our results show that EndoG interacts with both these proteins during apoptotic cell death. Therefore, we can conclude that EndoG and TOPO2a may actively participate in apoptotic chromatin degradation. The possible existence of a degradation complex consisting of EndoG and TOPO2a and possibly other proteins like AIF and cyclophilin A have yet to be investigated.

• MeSH
• antigeny nádorové chemie   genetika   metabolismus   MeSH
• apoptóza MeSH
• buněčné jádro enzymologie   patologie   MeSH
• časové faktory MeSH
• DNA vazebné proteiny chemie   genetika   metabolismus   MeSH
• DNA-topoisomerasy typu II chemie   genetika   metabolismus   MeSH
• endodeoxyribonukleasy chemie   genetika   metabolismus   MeSH
• HeLa buňky MeSH
• histony chemie   genetika   metabolismus   MeSH
• interakční proteinové domény a motivy MeSH
• konfokální mikroskopie MeSH
• konformace proteinů MeSH
• lidé MeSH
• mapování interakce mezi proteiny MeSH
• molekulární modely MeSH
• rekombinantní fúzní proteiny metabolismus   MeSH
• restrukturace chromatinu MeSH
• rezonanční přenos fluorescenční energie MeSH
• transfekce MeSH
• Check Tag
• lidé MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

Protoplast cultures are remarkable examples of plant cell dedifferentiation. The state of dedifferentiation is evidenced by changes in cell morphology, genome organization, as well as by the capability of protoplasts to differentiate into multiple types of cells (depending on the type of the stimulus applied). The first change in the genome structure is connected with large-scale chromatin decondensation, affecting chromocentres involving various types of these repetitive sequences. This paper describes not only the de- and recondensation of satellite DNA type I and 5S rDNA repetitive sequences, but it also compares the recondensation level of chromatin with the levels of oxidative stress which were decreased by using an antioxidant, as well as the capabilities of the antioxidative systems within protoplasts, during the first 72 h of their culture. It is demonstrated that the treatment of protoplasts with ascorbic acid not only decreased the level of oxidative stress but also positively stimulated the expression of the ascorbate peroxidase and catalase. It also led to a greater recondensation of the chromatin (when compared to the untreated protoplasts); in addition, it supported cell proliferation. It is concluded that large-scale genome relaxation is more directly connected with oxidative stress than with large changes in the expression of genes; and further, that its recondensation is related to the start of (as well as the level of) protection by the antioxidative systems.

• MeSH
• askorbátperoxidasa MeSH
• buněčné jádro enzymologie   genetika   metabolismus   MeSH
• Cucumis sativus enzymologie   genetika   metabolismus   MeSH
• katalasa genetika   metabolismus   MeSH
• mikrosatelitní repetice MeSH
• oxidační stres MeSH
• peroxidasy genetika   metabolismus   MeSH
• protoplasty enzymologie   metabolismus   MeSH
• rostlinné proteiny genetika   metabolismus   MeSH
• Publikační typ
• časopisecké články MeSH
• práce podpořená grantem MeSH

One of the most significant insults that jeopardize cardiomyocyte homeostasis is a surge of reactive oxygen species (ROS) in the failing myocardium. Early growth response factor-1 (Egr-1) has been found to act as a transcriptional regulator in multiple biological processes known to exert deleterious effects on cardiomyocytes. We thus investigated the signaling pathways involved in its regulation by H2O2. Egr-1 mRNA levels were found to be maximally induced after 2 h in H2O2-treated H9c2 cells. Egr-1 respective response at the protein level, was found to be maximally induced after 2 h of treatment with 200 µM H2O2, remaining elevated for 6 h, and declining thereafter. H2O2- induced upregulation of Egr-1 mRNA and protein levels was ablated in the presence of agents inhibiting ERKs pathway (PD98059) and JNKs (SP600125, AS601245). Immunofluorescent experiments revealed H2O2-induced Egr-1 nuclear sequestration to be also ERK- and JNK-dependent. Overall, our results show for the first time the fundamental role of ERKs and JNKs in regulating Egr-1 response to H2O2 treatment in cardiac cells at multiple levels: mRNA, protein and subcellular distribution. Nevertheless, further studies are required to elucidate the specific physiological role of Egr-1 regarding the modulation of gene expression and determination of cell fate.

• MeSH
• aktivní transport - buněčné jádro MeSH
• buněčné jádro enzymologie   účinky léků   MeSH
• buněčné linie MeSH
• časové faktory MeSH
• extracelulárním signálem regulované MAP kinasy antagonisté a inhibitory   metabolismus   MeSH
• financování organizované MeSH
• fluorescenční protilátková technika MeSH
• inhibitory proteinkinas farmakologie   MeSH
• JNK mitogenem aktivované proteinkinasy antagonisté a inhibitory   metabolismus   MeSH
• kardiomyocyty enzymologie   účinky léků   MeSH
• krysa rodu rattus MeSH
• messenger RNA metabolismus   MeSH
• peroxid vodíku farmakologie   MeSH
• protein 1 časné růstové odpovědi genetika   metabolismus   MeSH
• upregulace MeSH
• zvířata MeSH
• Check Tag
• krysa rodu rattus MeSH
• zvířata MeSH

Histone variants and their epigenetic modifications determine genome function, particularly transcription. However, whether regulation of gene expression can be influenced by nuclear organization or vice versa is not completely clear. Here, we analyzed the effect of epigenetic changes induced by a histone deacetylase inhibitor (HDACi) on the nuclear radial rearrangement of select genomic regions and chromosomes. The HDACi, sodium butyrate (NaBt), induced differentiation of human adenocarcinoma HT29 cells as well as a genome-wide increase in H3K9 acetylation. Three-dimensional analysis of nuclear radial distributions revealed that this increase in H3K9 acetylation was often associated with a repositioning of select loci and chromosomes toward the nuclear center. On the other hand, many centromeres resided sites more toward the nuclear periphery, similar to sites occupied by chromosome X. In more than two-thirds of events analyzed, central nuclear positioning correlated with a high level of H3K9 acetylation, while more peripheral positioning within interphase nuclei correlated with a lower level of acetylation. This was observed for the gene-rich chromosomes 17 and 19, TP53, and CCND1 genes as well as for gene-poor chromosome 18, APC gene, regions of low transcriptional activity (anti-RIDGEs), and the relatively transcriptionally less active chromosome X. These results are consistent with a role for epigenetic histone modifications in governing the nuclear radial positioning of genomic regions during differentiation.

• MeSH
• acetylace MeSH
• adenokarcinom enzymologie   genetika   MeSH
• buněčná diferenciace MeSH
• buněčné jádro enzymologie   patologie   účinky léků   MeSH
• buňky HT-29 MeSH
• butyráty farmakologie   MeSH
• cyklin D1 genetika   MeSH
• enterocyty účinky léků   enzymologie   patologie   MeSH
• epigeneze genetická účinky léků   MeSH
• financování organizované MeSH
• geny APC MeSH
• histondeacetylasy MeSH
• histony metabolismus   MeSH
• inhibitory enzymů farmakologie   MeSH
• inhibitory histondeacetylas MeSH
• lidé MeSH
• lidské chromozomy, pár 17 metabolismus   MeSH
• lidské chromozomy, pár 18 metabolismus   MeSH
• lidské chromozomy, pár 19 metabolismus   MeSH
• lidské chromozomy metabolismus   MeSH
• nádorový supresorový protein p53 genetika   MeSH
• nádory tračníku enzymologie   genetika   MeSH
• posttranslační úpravy proteinů účinky léků   MeSH
• proliferace buněk MeSH
• promotorové oblasti (genetika) MeSH
• regulace genové exprese u nádorů MeSH
• restrukturace chromatinu účinky léků   MeSH
• Check Tag
• lidé MeSH

For somatic cell nuclear transfer cytoplasts from metaphase II, oocytes are exclusively used. However, it is evident that certain reprogramming activities are present in oocytes even at earlier stages of maturation. These activities are, however, only poorly characterised. The main reason for this is that even the intrinsic oocyte processes are insufficiently understood. The mammalian oocyte is a highly specialised cell that harbours many specific characteristics. One of these is its particularly large size when compared to somatic cells. As the oocyte enters the growth phase its volume, as well as the amount of material, increases considerably. Thus, it is clear that the oocyte must possess the machinery to accomplish this incredible material accumulation. When the growth phase is completed, the transcription ceases and the oocyte becomes transcriptionally inactive. In our study, we have used the model system of oocyte fusion (transcribing x non-transcribing germinal vesicle (GV) stage oocytes) as a substitute for a somatic cell nuclear transfer schemes where the somatic cell nucleus would be introduced into a cytoplast obtained from a GV stage oocyte. We wanted to determine if the fully grown GV stage oocyte could induce reprogramming of transcriptionally active transferred nucleus by suppressing this activity. In order to evaluate possible changes in transcriptional properties after nuclear transfer, we also investigated the mechanism of transcriptional silencing taking place when the oocyte reaches its full size as well as the fate of the components namely of the RNA polymerase II (Pol II) transcriptional and splicing machinery. Here, we show that while the Pol II is degraded in fully grown GV stage oocytes and the splicing proteins undergo significant rearrangement, these oocytes are unable to induce similar changes in transcriptionally active nuclei even after a prolonged culture interval.

• MeSH
• buněčné jádro enzymologie   genetika   MeSH
• cytoplazma enzymologie   MeSH
• histondeacetylasa 1 metabolismus   MeSH
• myši inbrední ICR MeSH
• myši MeSH
• oocyty cytologie   ultrastruktura   MeSH
• přeprogramování buněk fyziologie   MeSH
• RNA-polymerasa II metabolismus   MeSH
• techniky jaderného přenosu MeSH
• umlčování genů MeSH
• zvířata MeSH
• Check Tag
• myši MeSH
• ženské pohlaví MeSH
• zvířata MeSH
• Publikační typ
• práce podpořená grantem MeSH