Spatiotemporal Mislocalization of Nuclear Membrane-Associated Proteins in γ-Irradiation-Induced Senescent Cells.

Cellular senescence, induced by genotoxic or replication stress, is accompanied by defects in nuclear morphology and nuclear membrane-heterochromatin disruption. In this work, we analyzed cytological and molecular changes in the linker of nucleoskeleton and cytoskeleton (LINC) complex proteins in senescence triggered by γ-irradiation. We used human mammary carcinoma and osteosarcoma cell lines, both original and shRNA knockdown clones targeting lamin B receptor (LBR) and leading to LBR and lamin B (LB1) reduction.

Consequences of Lamin B1 and Lamin B Receptor Downregulation in Senescence.

Anchoring of heterochromatin to the nuclear envelope appears to be an important process ensuring the spatial organization of the chromatin structure and genome function in eukaryotic nuclei. Proteins of the inner nuclear membrane (INM) mediating these interactions are able to recognize lamina-associated heterochromatin domains (termed LAD) and simultaneously bind either lamin A/C or lamin B1. One of these proteins is the lamin B receptor (LBR) that binds lamin B1 and tethers heterochromatin to the INM in embryonic and undifferentiated cells.

Loss of lamin B receptor is necessary to induce cellular senescence.

Cellular transition to senescence is associated with extensive chromatin reorganization and changes in gene expression. Recent studies appear to imply an association of lamin B1 (LB1) reduction with chromatin rearrangement in human fibroblasts promoted to senescence, while the mechanisms and structural features of these relationships have not yet been clarified. In this work, we examined the functions of LB1 and the lamin B receptor (LBR) in human cancer cells.

Medical and salutogenic approaches and their integration in taking prenatal and postnatal care of Czech women.

Objective: To compile a proposal of the system of taking complex prenatal, perinatal and postnatal care of pregnant women and their children in the Czech Republic with taking into account medical and salutogenic approaches.

Material And Methods: A questionnaire was prepared comprising questions for mothers and making it possible to exactly use specified data from their healthcare documentation. The method thus consisted of a secondary data analysis and subsequent contact with mothers.

Medical and salutogenic approaches and their integration in taking prenatal and postnatal care of immigrants.

Objectives: To compile a proposal of the system of taking complex prenatal, perinatal and postnatal care of pregnant immigrants in the Czech Republic with taking into account medical and salutogenic approaches.

Material And Methods: The research was implemented by the form of a controlled interview and was based on a questionnaire comprising 50 questions focused on the evaluation of taking the prenatal, natal and postnatal care of immigrants. The data were accumulated among immigrants from Vietnam, Mongolia and Ukraine.

Frequent chromatin rearrangements in myelodysplastic syndromes--what stands behind?

Myelodysplastic syndromes (MDS) represent a clinically and genetically heterogeneous group of clonal haematopoietic diseases characterized by a short survival and high rate of transformation to acute myeloid leukaemia (AML). In spite of this variability, MDS is associated with typical recurrent non-random cytogenetic defects. Chromosomal abnormalities are detected in the malignant bone-marrow cells of approximately 40-80 % of patients with primary or secondary MDS.

Determining Omics spatiotemporal dimensions using exciting new nanoscopy techniques to assess complex cell responses to DNA damage: part B--structuromics.

Recent groundbreaking developments in Omics and bioinformatics have generated new hope for overcoming the complexity and variability of (radio)biological systems while simultaneously shedding more light on fundamental radiobiological questions that have remained unanswered for decades. In the era of Omics, our knowledge of how genes and dozens of proteins interact in the frame of complex signaling and repair pathways (or, rather, networks) to preserve the integrity of the genome has been rapidly expanding. Nevertheless, these functional networks must be observed with strong correspondence to the cell nucleus, which is the main target of ionizing radiation.

Determining Omics spatiotemporal dimensions using exciting new nanoscopy techniques to assess complex cell responses to DNA damage: part A--radiomics.

Recent ground-breaking developments in Omics have generated new hope for overcoming the complexity and variability of biological systems while simultaneously shedding more light on fundamental radiobiological questions that have remained unanswered for decades. In the era of Omics, our knowledge of how genes and proteins interact in the frame of complex networks to preserve genome integrity has been rapidly expanding. Nevertheless, these functional networks must be observed with strong correspondence to the cell nucleus, which is the main target of ionizing radiation.

Inhibition of ATR kinase with the selective inhibitor VE-821 results in radiosensitization of cells of promyelocytic leukaemia (HL-60).

We compared the effects of inhibitors of kinases ATM (KU55933) and ATR (VE-821) (incubated for 30 min before irradiation) on the radiosensitization of human promyelocyte leukaemia cells (HL-60), lacking functional protein p53. VE-821 reduces phosphorylation of check-point kinase 1 at serine 345, and KU55933 reduces phosphorylation of check-point kinase 2 on threonine 68 as assayed 4 h after irradiation by the dose of 6 Gy. Within 24 h after gamma-irradiation with a dose of 3 Gy, the cells accumulated in the G2 phase (67 %) and the number of cells in S phase decreased.

Heterochromatinization associated with cell differentiation as a model to study DNA double strand break induction and repair in the context of higher-order chromatin structure.

Cell differentiation is associated with extensive gene silencing, heterochromatinization and potentially decreasing need for repairing DNA double-strand breaks (DSBs). Differentiation stages of blood cells thus represent an excellent model to study DSB induction, repair and misrepair in the context of changing higher-order chromatin structure. We show that immature granulocytes form γH2AX and 53BP1 foci, contrary to the mature cells; however, these foci colocalize only rarely and DSB repair is inefficient.

Function of chromatin structure and dynamics in DNA damage, repair and misrepair: γ-rays and protons in action.

According to their physical characteristics, protons and ion beams promise a revolution in cancer radiotherapy. Curing protocols however reflect rather the empirical knowledge than experimental data on DNA repair. This especially holds for the spatio-temporal organization of repair processes in the context of higher-order chromatin structure-the problematics addressed in this work.

DNA-dependent protein kinase and its inhibition in support of radiotherapy.

Purpose: Radiotherapy has been used as a treatment of almost 50% of all malignant tumors. The aim of this review is to provide a comprehensive overview of the recent knowledge in the field of molecular mechanisms of radiation-induced double-stranded breaks (DSB) repair. This paper gives particular emphasis to a key DNA repair enzyme, DNA-dependent protein kinase (DNA-PK), which plays a pivotal role in non-homologous end-joining.

Granulocyte maturation determines ability to release chromatin NETs and loss of DNA damage response; these properties are absent in immature AML granulocytes.

Terminally-differentiated cells cease to proliferate and acquire specific sets of expressed genes and functions distinguishing them from less differentiated and cancer cells. Mature granulocytes show lobular structure of cell nuclei with highly condensed chromatin in which HP1 proteins are replaced by MNEI. These structural features of chromatin correspond to low level of gene expression and the loss of some important functions as DNA damage repair, shown in this work and, on the other hand, acquisition of a new specific function consisting in the release of chromatin extracellular traps in response to infection by pathogenic microbes.

Valproic acid decreases the reparation capacity of irradiated MOLT-4 cells.

The aim of our work was to evaluate mechanisms leading to radiosensitization of MOLT-4 leukemia cells following valproic acid (VA) treatment. Cells were pretreated with 2 mM VA for 24 h followed by irradiation with a dose of 0.5 or 1 Gy.

Irradiated stem cells and ageing of the haematopoietic system.

In the work presented here, changes in haematopoiesis of mice (B6129SF2/J) were studied 1 year after their whole-body exposure to a dose of 7 Gy (72% of mice survived). The irradiated mice were compared with non-irradiated younger (4 months of age) and older (16 months of age) mice. There was a significant increase in the relative abundance of primitive stem cells with long-term capability of the haematopoiesis recovery lin(-)/Sca-1(+)/CD117(+)/CD34(-) in the bone marrow of mice aged 16 months (irradiated and non-irradiated) compared with those aged 4 months.

The BRCA1 alternative splicing variant Δ14-15 with an in-frame deletion of part of the regulatory serine-containing domain (SCD) impairs the DNA repair capacity in MCF-7 cells.

The BRCA1 gene codes for a protein involved in the DNA double strand break (DDSB) repair. Alongside the dominant full-length splicing form of BRCA1, numerous endogenously expressed alternative splicing variants of unknown significance have been described in various tissues. Some of them retain the original BRCA1 reading frame but lack several critical BRCA1 structural domains, suggesting an altered function of the resulting protein in the BRCA1-regulated processes.

Accumulation of DNA damage and cell death after fractionated irradiation.

The purpose of this work was to determine how fractionated radiation used in the treatment of tumors affects the ability of cancer as well as normal cells to repair induced DNA double-strand breaks (DSBs) and how cells that have lost this ability die. Lymphocytic leukemia cells (MOLT4) were used as an experimental model, and the results were compared to those for normal cell types. The results show that cancer and normal cells were mostly unable to repair all DSBs before the next radiation dose induced new DNA damage.

[Detection of Francisella tularensis by blood culture].

Francisella tularensis, from the family Francisellaceae, is the aetiological agent of a zoonosis called tularaemia, spread throughout the northern hemisphere. The infectious dose is extremely low (10 CFU/ml) and the infection causes severe diseases or even death if untreated. The transmission to humans is always related to animals, either by a direct contact or by a contact with the environment contaminated by them.

[Tularaemia - an overview of the current knowledge].

Francisella tularensis belongs to the family Francisellaceae. It is the aetiological agent of a zoonosis called tularaemia, spread throughout the northern hemisphere. Currently, several subspecies of F.

Higher-order chromatin structure in DSB induction, repair and misrepair.

Double-strand breaks (DSBs), continuously introduced into DNA by cell metabolism, ionizing radiation and some chemicals, are the biologically most deleterious type of genome damage, and must be accurately repaired to protect genomic integrity, ensure cell survival, and prevent carcinogenesis. Although a huge amount of information has been published on the molecular basis and biological significance of DSB repair, our understanding of DSB repair and its spatiotemporal arrangement is still incomplete. In particular, the role of higher-order chromatin structure in DSB induction and repair, movement of DSBs and the mechanism giving rise to chromatin exchanges, and many other currently disputed questions are discussed in this review.

Chromatin structure influences the sensitivity of DNA to gamma-radiation.

For the first time, DNA double-strand breaks (DSBs) were directly visualized in functionally and structurally different chromatin domains of human cells. The results show that genetically inactive condensed chromatin is much less susceptible to DSB induction by gamma-rays than expressed, decondensed domains. Higher sensitivity of open chromatin for DNA damage was accompanied by more efficient DSB repair.

Lamin A/C and polymeric actin in genome organization.

In this work, we have studied the structural and functional linkage between lamin A/C, nuclear actin, and organization of chromosome territories (CTs) in mammary carcinoma MCF-7 cells. Selective down-regulation of lamin A/C expression led to disruption of the lamin A/C perinuclear layer and disorganization of lamin-bound emerin complexes at the inner nuclear membrane. The silencing of lamin A/C expression resulted in a decrease in the volume and surface area of chromosome territories, especially in chromosomes with high heterochromatin content.

Changes in phosphorylation of histone H2A.X and p53 in response of peripheral blood lymphocytes to gamma irradiation.

The main aim of this study was to compare the reaction of quiescent and proliferating, i.e. phytohemagglutinin (PHA)-stimulated, human peripheral blood mononuclear cells (PBMCs) to gamma-radiation, and analyse changes of proteins related to repair of DNA damage and apoptosis, such as gammaH2A.

Intranuclear trafficking of plasmid DNA is mediated by nuclear polymeric proteins lamins and actin.

Functions of nuclear polymeric proteins such as lamin A/C and actin in transport of plasmid DNA were studied. The results show that the lamina plays an important role in plasmid DNA's entry into the cell nucleus from the cytoplasm. Selective disruption of lamin A/C led to a halt in plasmid DNA transport through the nuclear envelope.